Patent Application
20230396100
The present disclosure relates to contactless power supply systems and power reception apparatuses.
Various contactless power supply systems have been proposed in which electric power is supplied from a primary side to a secondary side in a contactless manner by induction; the primary side is a power transmission side whereas the secondary side is a power reception side. For example, in Japanese Unexamined Patent Application Publication No. JP2010088178A, there is disclosed a configuration of performing, by a handshake through two-way wireless communication, both positioning between a power transmission apparatus and a power reception apparatus and a power supply start procedure between the power transmission apparatus and the power reception apparatus and thereby automatically performing supply of electric power from the power transmission apparatus to the power reception apparatus.
However, a handshake through two-way wireless communication tends to require time for the procedure until the supply of electric power actually starts; thus, there is a problem in terms of fast responsiveness. This problem becomes remarkable particularly in, for example, a system for supplying electric power to a traveling vehicle. Moreover, the execution of a handshake through two-way wireless communication requires equipment employing circuits for performing complicated signal processing; thus, simplification of such equipment is desired.
The present disclosure has been accomplished to in view of the problem.
According to one aspect of the present disclosure, there is provided a contactless power supply system in which supply of electric power from a power transmission apparatus to a power reception apparatus is performed in a contactless manner. The contactless power supply system includes the power transmission apparatus and the power reception apparatus. The power transmission apparatus includes: a primary-side resonant circuit having a primary-side coil for power transmission and a primary-side capacitor; and an AC power supply apparatus configured to supply AC power of a predetermined operating frequency to the primary-side resonant circuit. The power reception apparatus includes: a secondary-side resonant circuit having a secondary-side coil for power reception, which is to be magnetically coupled with the primary-side coil, and a secondary-side capacitor; and a load apparatus configured to use electric power outputted from the secondary-side resonant circuit. The primary-side resonant circuit has an impedance varying element that increases, when the supply of electric power is stopped, an input impedance of the primary-side resonant circuit so as to have predetermined standby current flowing through the primary-side coil. The power reception apparatus further includes a magnetic flux amplifier circuit configured to amplify magnetic flux generated by the standby current flowing through the primary-side coil. The power transmission apparatus further includes a primary-side detection circuit configured to detect a change in a voltage of the primary-side coil, a change in electric current flowing through the primary-side coil or a change in a magnetic field in the vicinity of the primary-side coil; each of the change in the voltage, the change in the electric current and the change in the magnetic field is caused by the magnetic flux amplified by the magnetic flux amplifier circuit. In the contactless power supply system according to this aspect, the presence of the power reception apparatus can be detected by the primary-side detection circuit in the power transmission apparatus. Consequently, supply of electric power from the power transmission apparatus to the power reception apparatus can be automatically performed without performing a handshake through communication between the power transmission side and the power reception side.
According to another aspect of the present disclosure, there is provided a contactless power supply system in which supply of electric power from a power transmission apparatus to a power reception apparatus is performed in a contactless manner. The contactless power supply system includes the power transmission apparatus and the power reception apparatus. The power transmission apparatus includes: a primary-side resonant circuit having a primary-side coil for power transmission and a primary-side capacitor; an AC power supply apparatus configured to supply AC power of a predetermined operating frequency to the primary-side resonant circuit; and a power-transmission-apparatus detection section provided at the primary-side coil or near the primary-side coil. The power reception apparatus includes: a secondary-side resonant circuit having a secondary-side coil for power reception, which is to be magnetically coupled with the primary-side coil, and a secondary-side capacitor; a load apparatus configured to use electric power outputted from the secondary-side resonant circuit; an activation circuit having an activation coil and a pulse generation circuit configured to supply AC current of the operating frequency to the activation coil; and a power-transmission-apparatus detecting unit configured to detect the power-transmission-apparatus detection section. In response to detection of the power-transmission-apparatus detection section by the power-transmission-apparatus detecting unit, the activation circuit supplies the AC current from the pulse generation circuit to the activation coil. The power transmission apparatus further includes a primary-side detection circuit configured to detect a change in a voltage of the primary-side coil, a change in electric current flowing through the primary-side coil or a change in a magnetic field in the vicinity of the primary-side coil; each of the change in the voltage, the change in the electric current and the change in the magnetic field is caused by magnetic flux generated by the activation coil with the supplied AC current. In the contactless power supply system according to this aspect, the presence of the power reception apparatus can be detected by the primary-side detection circuit without having standby current flow through the power transmission apparatus. Consequently, supply of electric power from the power transmission apparatus to the power reception apparatus can be automatically performed without performing a handshake through communication between the power transmission side and the power reception side.
According to yet another aspect of the present disclosure, there is provided a power reception apparatus configured to receive, in a contactless manner, electric power transmitted from a power transmission apparatus. The power reception apparatus includes: a secondary-side resonant circuit that includes a secondary-side coil for power reception, which is to be magnetically coupled with a primary-side coil for power transmission included in the power transmission apparatus, and a secondary-side capacitor; a load apparatus configured to use electric power outputted from the secondary-side resonant circuit; and a magnetic flux amplifier circuit configured to amplify magnetic flux generated by predetermined standby current flowing through the primary-side coil. With the power reception apparatus according to this aspect, a primary-side detection circuit of the power transmission apparatus can detect the presence of the power reception apparatus. Consequently, supply of electric power from the power transmission apparatus to the power reception apparatus can be automatically performed without performing a handshake through communication between the power transmission side and the power reception side.
According to still another aspect of the present disclosure, there is provided a power reception apparatus configured to receive, in a contactless manner, electric power transmitted from a power transmission apparatus. The power reception apparatus includes: a secondary-side resonant circuit that includes a secondary-side coil for power reception, which is to be magnetically coupled with a primary-side coil for power transmission included in the power transmission apparatus, and a secondary-side capacitor; a load apparatus configured to use electric power outputted from the secondary-side resonant circuit; an activation circuit that includes an activation coil and a pulse generation circuit configured to supply AC current of a predetermined operating frequency to the activation coil; and a power-transmission-apparatus detecting unit configured to (i) detect a power-transmission-apparatus detection section provided at the primary-side coil or near the primary-side coil and (ii) cause, upon detecting the power-transmission-apparatus detection section, the pulse generation circuit to supply the AC current to the activation coil. With the power reception apparatus according to this aspect, a primary-side detection circuit of the power transmission apparatus can detect the presence of the power reception apparatus without having standby current flow through the power transmission apparatus. Consequently, supply of electric power from the power transmission apparatus to the power reception apparatus can be automatically performed without performing a handshake through communication between the power transmission side and the power reception side.
Exemplary embodiments will be described hereinafter with reference to the drawings. It should be noted that for the sake of clarity and understanding, identical components having identical functions throughout the whole description have been marked, where possible, with the same reference numerals in the drawings and that for the sake of avoiding redundancy, descriptions of identical components will not be repeated.
As shown in
The power transmission apparatus 100 includes a primary-side resonant circuit 110, a primary-side detection circuit 120 and an AC power supply apparatus 130. The primary-side resonant circuit 110 is a circuit that performs supply of electric power to the power reception apparatus 200 by induction through resonance.
The primary-side resonant circuit 110 includes a primary-side coil 112, and a primary-side capacitor 114 connected in series with the primary-side coil 112. The primary-side capacitor 114 is a resonant capacitor for resonating electric power applied to the primary-side coil 112. The primary-side capacitor 114 is implemented by a variable capacitor whose capacitance is variable. Specifically, the primary-side capacitor 114 is implemented by a variable capacitor whose capacitance C1 changes according to a control input applied thereto, more particularly according to a control voltage Vc applied thereto in the present embodiment. The primary-side resonant circuit 110 is a circuit that transmits AC power, in a resonant coupling state where the primary-side coil 112 for power transmission and a secondary-side coil 212 for power reception are magnetically coupled with each other, to the secondary-side coil 212. As will be described later, the secondary-side coil 212 is included in a secondary-side resonant circuit 210 of the power reception apparatus 200.
The AC power supply apparatus 130 is an apparatus that applies AC power having a predetermined operating frequency to the primary-side resonant circuit 110. Specifically, the AC power supply apparatus 130 is configured as an apparatus that includes a power supply that converts AC power from an external power supply into DC power, and an inverter that converts the DC power supplied from the power supply into the AC power having the operating frequency. In addition, a filter may be provided on an output side of the inverter. Hereinafter, the AC voltage applied to the primary-side resonant circuit 110 by the AC power supply apparatus 130 will be denoted by V1; the AC current flowing through the primary-side resonant circuit 110 will be denoted by I1; the operating frequency will be denoted by f0; and the operating angular frequency will be denoted by ω0 (=2π·f0).
The primary-side detection circuit 120 includes a detection circuit 124 and a C control circuit 126. The detection circuit 124 detects whether there is an increase in a primary-side coil voltage VL1 generated between terminals of the primary-side coil 112, thereby detecting whether there is the power reception apparatus 200 in a state capable of receiving electric power from the power transmission apparatus 100. In addition, an increase in the primary-side coil voltage VL1 is generated by a magnetic flux amplifier circuit 220 which will be described later. The C control circuit 126 outputs the control voltage Vc according to a detection signal Sd, thereby controlling the capacitance C1 of the primary-side capacitor 114. In addition, operation of the primary-side detection circuit 120 will be explained later together with operation of the magnetic flux amplifier circuit 220.
In the case where the detection signal Sd is in an active state indicating “detection”, the capacitance C1 is set to a value such that the input impedance Z1 (i.e., V1/I1) of the primary-side resonant circuit 110 becomes low and thus high coil current for electric power supply will flow through the primary-side coil 112. This setting is performed by setting the control voltage Vc corresponding to the capacitance C1 for electric power supply to be the control input of the primary-side capacitor 114. On the other hand, in the case where the detection signal Sd is in an inactive state indicating “non-detection”, the capacitance C1 is set to a value such that the input impedance Z1 of the primary-side resonant circuit 110 becomes high and thus low coil current for standby will flow through the primary-side coil 112. This setting is performed by setting the control voltage Vc corresponding to the capacitance C1 for standby to be the control input of the primary-side capacitor 114. Hereinafter, the case where the detection signal Sd is in the active state will be referred to as “when supplying electric power”; and the case where the detection signal Sd is in the inactive state will be referred to as “when not supplying electric power”. Moreover, the high coil current for electric power supply will be referred to as the “power supply current”; and the low coil current for standby will be referred to as the “standby current”.
The input impedance Z1 can be simply expressed by Z1=j[ω0·L1−1/(ω0·C1)]. Here, L1 is the self-inductance of the primary-side coil 112. Therefore, to reduce the input impedance Z1, the capacitance C1 may be set so that the absolute value of [ω0·L1−1/(ω0·C1)] becomes a predetermined value. In contrast, to increase the input impedance Z1, the capacitance C1 may be set to be lower than in the case of reducing the input impedance Z1, so that the input impedance Z1 has a value corresponding to a predetermined value of the standby current. From the above, in the case of reducing the input impedance Z1, the capacitance C1 is set to the capacitance for electric power supply; otherwise, in the case of increasing the input impedance Z1, the capacitance C1 is set to the capacitance for standby. In addition, as can be seen from the above explanation, the primary-side capacitor 114 corresponds to an “impedance varying element” that varies the input impedance Z1.
The power reception apparatus 200 may be installed in various apparatuses that operate on electric power, such as electronic devices and electric vehicles. The power reception apparatus 200 includes a secondary-side resonant circuit 210, a magnetic flux amplifier circuit 220 and a load apparatus 240.
Similar to the primary-side resonant circuit 110, the secondary-side resonant circuit 210 has a secondary-side coil 212 and a secondary-side capacitor 214 connected in series with each other; the secondary-side capacitor 214 is a resonant capacitor. The secondary-side resonant circuit 210 is a circuit that obtains AC power induced in the secondary-side coil 212 in the resonant coupling state where the secondary-side coil 212 and the primary-side coil 112 are magnetically coupled with each other.
The load apparatus 240 is an apparatus that uses the AC power induced in the secondary-side resonant circuit 210. For example, the load apparatus 240 may be an apparatus that receives the AC power obtained by the secondary-side resonant circuit 210 and charges a battery with the received AC power. Specifically, the load apparatus 240 may include, for example, a power reception circuit and a battery. Further, the power reception circuit may include, for example, a rectifier circuit that converts the AC power into DC power that can be supplied to the battery, and a DC-to-DC converter if necessary. The electric power charged in the battery may be used as an electric power in the apparatus where the power reception apparatus 200 is installed. It should be noted that the load apparatus 240 is not limited to the apparatus that includes the power reception circuit and the battery, but may be implemented by various apparatuses that can use the AC power outputted from the secondary-side resonant circuit 210.
The magnetic flux amplifier circuit 220 is configured with a closed circuit in which an amplification coil 222 and an amplification capacitor 224 are connected in series with each other. The capacitance C3 of the amplification capacitor 224 is set to be C3=1/(ω02·L3) with respect to the self-inductance L3 of the amplification coil 222, so that the operating frequency f0 becomes the resonant frequency of the magnetic flux amplifier circuit 220. In addition, operation of the magnetic flux amplifier circuit 220 will be explained later together with operation of the primary-side detection circuit 120. The amplification coil 222 is fixedly arranged at a position where it is in a constant coupling state with the secondary-side coil 212.
The capacitance C1 of the primary-side capacitor 114 when supplying electric power is set to be C1=1/(ω02·L1) with respect to the self-inductance L1 of the primary-side coil 112, so that the operating frequency fb becomes the resonant frequency of the primary-side resonant circuit 110. Moreover, the capacitance C1 when supplying electric power may alternatively be set to be C1=1/[ω02·L1(1−k13·k12/k32)] taking into account the mutual coupling coefficients of the primary-side coil 112, the secondary-side coil 212 and the amplification coil 222. Here, knm represents the coupling coefficient between the nth-order-side coil and the mth-order-side coil. Otherwise, the capacitance C1 when supplying electric power may alternatively be set so that the xth-order (x is a positive number greater than or equal to 2) harmonic frequency of the operating frequency f0 becomes the resonant frequency of the primary-side resonant circuit 110. That is, the capacitance C1 when supplying electric power may be set, under various predetermined setting conditions and based on the self-inductance L1 of the primary-side coil 12, the operating frequency f0 (or the operating angular frequency ω0), the coupling coefficients knm and the like, so that the AC power having the operating frequency f0 can be efficiently transferred between the primary-side resonant circuit 110 and the secondary-side resonant circuit 210.
On the other hand, the capacitance C1 when not supplying electric power is set to a value sufficiently less than the value of the capacitance C1 when supplying electric power, so that the input impedance Z1 has the value corresponding to the predetermined value of the standby current.
Similar to the capacitance C1 when supplying electric power, the capacitance C2 of the secondary-side capacitor 214 is set to be C2=1/(ω02·L2) with respect to the self-inductance L2 of the secondary-side coil 212, so that the operating frequency f0 becomes the resonant frequency of the secondary-side resonant circuit 210. Moreover, the capacitance C2 may alternatively be set to be C2=1/[ω02·L2 (1−k32·k12/k13)] taking into account the mutual coupling coefficients of the primary-side coil 112, the secondary-side coil 212 and the amplification coil 222. Otherwise, the capacitance C2 may alternatively be set so that the xth-order harmonic frequency of the operating frequency if) becomes the resonant frequency of the secondary-side resonant circuit 210. That is, the capacitance C2 may be set, under various predetermined setting conditions and based on the self-inductance L2 of the secondary-side coil 212, the operating frequency f0 (or the operating angular frequency ω0), the coupling coefficients knm and the like, so that the AC power having the operating frequency f0 can be efficiently transferred between the primary-side resonant circuit 110 and the secondary-side resonant circuit 210.
It should be noted that in
Hereinafter, operations of the magnetic flux amplifier circuit 220 and the primary-side detection circuit 120 will be described. In the power transmission apparatus 100, first, it is assumed that the capacitance C1 of the primary-side capacitor 114 is set to a state when not supplying electric power. In this case, the AC voltage V1 is applied, by the AC power supply apparatus 130, between the terminals of the primary-side coil 112; thus magnetic flux corresponding to the AC standby current flowing through the primary-side coil 112 is generated.
When the power reception apparatus 200 approaches the power transmission apparatus 10 in the above-described state and thus magnetic coupling is established between the amplification coil 222 of the magnetic flux amplifier circuit 220 and the primary-side coil 112, the amplification coil 222 of the magnetic flux amplifier circuit 220 generates induced magnetic flux according to the increase in the degree of the coupling. The induced magnetic flux increases magnetic flux crossing the primary-side coil 112. That is, the magnetic flux amplifier circuit 220 substantially amplifies the magnetic flux in the vicinity of the primary-side coil 112, thereby enhancing the magnetic field.
Accordingly, as shown in
Therefore, in the primary-side detection circuit 120 (see
In particular, in the case of the magnetic flux amplifier circuit 220 being implemented by a short-circuited resonant circuit whose resonant frequency is set to the operating frequency f), if the Q factor of the short-circuited resonant circuit is sufficiently high, the primary-side coil voltage VL1 can be expressed by VL1=(k132·Q3)V1. That is, the primary-side coil voltage VL1 can be [k132·Q3] times the voltage V1 applied by the AC power supply apparatus 130. Here, Q3 is the Q factor of the short-circuited resonant circuit; and Q3 can be expressed by Q3=ω0·L3/r3, where r3 is the winding resistance of the amplification coil 222. Consequently, the increase in the primary-side coil voltage VL1 can be amplified, thereby improving the stability of the detection thereof.
Hence, the power transmission apparatus 100 can detect, without performing communication with the power reception apparatus 200, the fact that the secondary-side coil 212. i.e., the power reception apparatus 200 is in a state capable of receiving electric power from the power transmission apparatus 100.
Moreover, as described above, when the detection signal Sd is switched from the inactive state to the active state, the primary-side detection circuit 120 can set, by the C control circuit 126, the capacitance C1 of the primary-side capacitor 114 to a state when supplying electric power. In contrast, when the detection signal Sd is switched from the active state to the inactive state, the primary-side detection circuit 120 can set, by the C control circuit 126, the capacitance C1 to the state when not supplying electric power.
Hence, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, the speed of the detection of the presence or absence of the power reception apparatus 200 at the power transmission apparatus 100 depends on the responsiveness of the circuits constituting the power transmission apparatus 100 and the power reception apparatus 200; and the responsiveness of the circuits is faster than that of a handshake through communication. Therefore, the automatic supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be started faster than in the case of performing a handshake through communication.
In addition, although the primary-side detection circuit 120 shown in
In this case, as shown in
Otherwise, as shown in
In this case, as shown in
In the first embodiment, a variable capacitor element whose capacitance changes according to the control voltage Vc is employed as the primary-side capacitor 114; and the primary-side capacitor 114 constitutes the impedance varying element. However, the impedance varying element may alternatively be constituted of a primary-side capacitor 114b as shown in
The primary-side capacitor 114b is a variable capacitor unit that is constituted of a first capacitor 114b1, a switch 114b3 connected in series with the first capacitor 114b1, and a second capacitor 114b2 connected in parallel with the first capacitor 114b1 and the switch 114b3. The capacitance Cs of the second capacitor 114b2 is lower than the capacitance C1 of the first capacitor 114b1. In addition, the switch 114b3 may be configured with, for example, a bidirectional switch circuit.
The first capacitor 114b1 is connected in parallel with the second capacitor 114b2 when the switch 114b3 is in an on-state, and released when the switch 114b3 is turned off. Therefore, the capacitance C1 of the primary-side capacitor 114b is represented by the capacitance Cs of the second capacitor 114b2 when the switch 114b3 is in an off-state, and represented by the sum [C1+Cs] of the capacitance C1 of the first capacitor 114b1 and the capacitance Cs of the second capacitor 114b2 when the switch 114b3 is in the on-state. In addition, in the present embodiment, [C1+Cs] is set to the capacitance for electric power supply described in the first embodiment; and Cs is set to the capacitance for standby described in the first embodiment.
The primary-side detection circuit 120 includes an S control circuit 126b instead of the C control circuit 126 shown in
With the above configuration of the contactless power supply system according to the second embodiment, it is also possible to automatically perform, as described in the first embodiment, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, the automatic supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be started faster than in the case of performing a handshake through communication.
In the first and second embodiments, the impedance varying element is constituted of the primary-side capacitor 114 or 114b of the primary-side resonant circuit 110 (see
The impedance varying element 116 is constituted of: an impedance varying capacitor 116c1 connected in series with the primary-side capacitor 114c; and a switch 116c2 for short-circuiting terminals of the impedance varying capacitor 116c1.
In the present embodiment, the primary-side detection circuit 120 includes an S control circuit 126c instead of the C control circuit 126 (see
With the above configuration of the contactless power supply system according to the third embodiment, it is also possible to automatically perform, as described in the first and second embodiments, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, the automatic supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be started faster than in the case of performing a handshake through communication.
Although the impedance varying element 116 has been described taking the configuration of employing the impedance varying capacitor 116c1 as an example, the impedance varying element 116 is not limited to the impedance varying capacitor 116c1, but may alternatively be any element whose impedance when the switch 116c2 is turned off has an amplitude corresponding to the standby current, such as a resistor, a reactor or the like.
In addition, in the case of the above-described impedance varying element 116 in which the impedance varying capacitor 116c1 is employed, the combination of the impedance varying element 116 and the primary-side capacitor 114c can be regarded as a variable capacitor unit constituting a primary-side capacitor, like the primary-side capacitor 114b (see
As in the power reception apparatus 200 shown in
The power reception apparatus 200 according to the fourth embodiment includes, instead of the magnetic flux amplifier circuit 220 (see
The switch 216 corresponds to a short-circuiting switch circuit that short-circuits the secondary-side coil 212 and the secondary-side capacitor 214, which are connected in series with each other, to form a closed circuit. In addition, the switch 216 may be configured with, for example, a bidirectional switch circuit.
The capacitance C2 of the secondary-side capacitor 214 of the secondary-side resonant circuit 210 is set to be C2=1/(ω02·L2) with respect to the self-inductance L2 of the secondary-side coil 212, so that the operating frequency f0 becomes the resonant frequency of the secondary-side resonant circuit 210.
When the switch 216 is in the off-state, the secondary-side resonant circuit 210 is in a state capable of receiving electric power from the primary-side resonant circuit 110 of the power transmission apparatus 100. In contrast, when the switch 216 is in the on-state, the secondary-side resonant circuit 210 functions as a magnetic flux amplifier circuit that is configured with a short-circuited resonant circuit.
Therefore, in the power reception apparatus 200, w % ben supply of electric power from the power transmission apparatus 100 is required, the switch 216 may be kept in the on-state for a given period of time, thereby having the secondary-side resonant circuit 210 operate as a magnetic flux amplifier circuit. In this case, as described in the first embodiment, the power transmission apparatus 100 can automatically detect the presence of the power reception apparatus 200 in a state capable of receiving electric power and operate to supply electric power to the power reception apparatus 200. Consequently, in the fourth embodiment, it is also possible to automatically perform supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, in the fourth embodiment, it becomes possible to omit, from the configuration of the power reception apparatus 200, the amplification coil 222 and the amplification capacitor 224 that together constitute the dedicated magnetic flux amplifier circuit 220 (see
In addition, in the above example, the S control circuit 252 keeps the switch 216 in the on-state for a given period of time. However, the present disclosure is not limited to this example. Alternatively, the S control circuit 252 may turn off the switch 216 in response to detection that the coil current flowing through the secondary-side coil 212 of the secondary-side resonant circuit 210 operating as the short-circuited resonant circuit has increased and thereby the power transmission apparatus 100 has been brought into a state capable of supplying electric power.
The power reception apparatus 200 shown in
In the power reception apparatus 200 according to the fifth embodiment, the load apparatus 240 includes a rectifier circuit 242 as a power reception circuit and a battery 244. The immittance filter 230 is provided between the secondary-side resonant circuit 210 and the rectifier circuit 242. The immittance filter 230 is a T-LCL immittance filter that is constituted of a pair of inductors 232 and 234 and a capacitor 236. The inductance Le of the inductors 232 and 234 and the capacitance Ce of the capacitor 236 are set so as to obtain immittance characteristics at the operating frequency f0, i.e., to satisfy ω02=1/(Le·Ce).
In addition, the capacitance C2 of the secondary-side capacitor 214 of the secondary-side resonant circuit 210 is set to be C2=1/(ω02·L2) with respect to the self-inductance L2 of the secondary-side coil 212, so that the operating frequency f0 becomes the resonant frequency of the secondary-side resonant circuit 210.
The voltage between the output terminals of the rectifier circuit 242 is required to be higher than the voltage between the input terminals so as not to generate a forward voltage in the diodes. This may be achieved by, for example, the battery 244 having an amount of electric power storage greater than or equal to a value corresponding to the required voltage. In this case, the input impedance of the rectifier circuit 242 becomes high so that the state of the rectifier circuit 242 is substantially equivalent to that in the case of the rectifier circuit 242 being disconnected from the output terminals of the immittance filter 230. As a result, both the secondary-side coil 212 and the secondary-side capacitor 214 of the secondary-side resonant circuit 210 and both the inductor 232 and the capacitor 236 on the input side of the immittance filter 230 together form the short-circuited resonant circuit that resonates at the operating frequency fb, functioning as the magnetic flux amplifier circuit.
Therefore, when no electric power is supplied from the power transmission apparatus 100 to the power reception apparatus 200, e.g., when the power transmission apparatus 100 is in a standby state, the short-circuited resonant circuit configured with the secondary-side resonant circuit 210 and the immittance filter 230 of the power reception apparatus 200 operates as the magnetic flux amplifier circuit. Consequently, as described in the first embodiment, the power transmission apparatus 100 can automatically detect the presence of the power reception apparatus 200 in a state capable of receiving electric power and operate to supply electric power to the power reception apparatus 200.
As described above, in the fifth embodiment as well, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, as in the fifth embodiment, in the case of the power reception apparatus 200 including an immittance filter 230 that can be widely used to remove harmonic noise, the amplification coil 222 and the amplification capacitor 224 that constitute the dedicated magnetic flux amplifier circuit 220 (see
In addition, as in the power reception apparatus 200 shown in
Otherwise, as in the power reception apparatus 200 shown in
In addition, as the variable capacitor constituting the secondary-side capacitor 214e, a variable capacitor unit may be employed which includes a plurality of capacitors in the same manner as the primary-side capacitor 114b (see
In the above-described first to fifth embodiments, the magnetic flux amplifier circuit is constituted of a short-circuited resonant circuit. However, as will be described below, the magnetic flux amplifier circuit may be constituted of a circuit that generates magnetic flux changing at the operating frequency f0.
The power reception apparatus 200 shown in
As described in the first embodiment, the capacitance C2 of the secondary-side capacitor 214 of the secondary-side resonant circuit 210 may be set, under various predetermined setting conditions and based on the self-inductance L2 of the secondary-side coil 212, the operating frequency f0 (or the operating angular frequency ω0), the coupling coefficients knm and the like, so that the AC power having the operating frequency f0 can be efficiently transferred between the primary-side resonant circuit 110 and the secondary-side resonant circuit 210.
The magnetic flux amplifier circuit 220f includes an amplification coil 222, a pulse generation circuit 226, a DC power supply 228 and a drive circuit 229. It should be noted that the DC power supply 228 may be omitted and the battery 244 may be used instead. The pulse generation circuit 226 is a circuit that converts, according to a drive signal supplied from the drive circuit 229, the DC voltage outputted from the DC power supply 228 into an AC voltage (or pulse voltage) having a frequency equal to the operating frequency f0 and applies the AC voltage to the amplification coil 222. The drive circuit 229 supplies the aforementioned drive signal to the pulse generation circuit 226 when a drive control signal Smd is in an active state, the drive control signal Smd is supplied from the secondary-side detection circuit 260 which will be described later. The amplification coil 222 generates magnetic flux according to AC current flowing therethrough due to the AC voltage applied thereto.
The secondary-side detection circuit 260 includes a magnetic flux detection element 262, a detection circuit 264 and a determination circuit 266. The magnetic flux detection element 262 is constituted of a magnetic sensor, a coil or the like. The detection circuit 264 detects, based on the change in an output value of the magnetic flux detection element 262, the magnetic flux generated by the standby current in the power transmission apparatus 100. The determination circuit 266 determines the presence or absence of the power transmission apparatus 100 based on the change in magnetic flux detected by the detection circuit 264. Specifically, when the magnetic flux detected by the detection circuit 264 has increased to become greater than or equal to a predetermined value, the determination circuit 266 determines that there is the power transmission apparatus 100 in a state capable of supplying electric power, and keeps the drive control signal Smd in the active state for a given period of time. Consequently, as described above, the magnetic flux amplifier circuit 220f is driven by the drive circuit 229 to generate magnetic flux that changes at the operating frequency M. As a result, as described in the first embodiment, upon the magnetic flux (or magnetic field) in the vicinity of the primary-side coil 112 being amplified, the power transmission apparatus 100 can detect the presence of the power reception apparatus 200 and supply electric power to the power reception apparatus 200.
With the above configuration of the contactless power supply system according to the sixth embodiment, it is also possible to automatically perform, as described in the first embodiment, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, the automatic supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be started faster than in the case of performing a handshake through communication.
In addition, in the case of the magnetic flux amplifier circuit being constituted of a short-circuited resonant circuit as in the first embodiment, the amplification rate of the coil voltage of the primary-side coil generated by the magnetic flux generated by the magnetic flux amplifier circuit is (k132·Q3) as described above. That is, the amplification rate depends on the coupling coefficient k13 between the primary-side coil 112 and the amplification coil 222 and the Q value Q3 of the short-circuited resonant circuit; therefore, there is a limit on the amplification rate. In contrast, the amplification rate of the coil voltage of the primary-side coil 112 by the magnetic flux generated by the magnetic flux amplifier circuit 220f according to the sixth embodiment can be changed depending on the magnitude of the AC current supplied from the pulse generation circuit 226 to the amplification coil 222. Therefore, it is possible to considerably increase the amplification rate of the coil voltage and thereby improve the stability of the detection of the coil voltage as compared with the case of the magnetic flux amplifier circuit being constituted of a short-circuited resonant circuit. The same applies to the case of detecting the coil current flowing through the primary-side coil, and to the case of detecting the magnetic flux (or magnetic field) in the vicinity of the primary-side coil.
In the above-described secondary-side detection circuit 260, the detection circuit 264 detects the change in the output value of the magnetic flux detection element 262. However, the detection circuit 264 may alternatively detect the change in the voltage between the terminals of the secondary-side coil 212 or the change in the electric current flowing through the secondary-side coil 212.
Moreover, in the above-described example, the drive control signal Smd is kept in the active state for a given period of time. However, the present disclosure is not limited to this example. Alternatively, the drive control signal Smd may be switched to an inactive state in response to detection of an increase in the coil current flowing through the secondary-side coil 212 of the secondary-side resonant circuit 210 or in the voltage between the terminals of the secondary-side coil 212 due to the power transmission apparatus 100 being brought into a state capable of supplying electric power.
When the pulse generation circuit 226 causes AC current to flow through the amplification coil 222, it is preferable for the ampere-turns of the amplification coil 222 to be less than or equal to the ampere-turns of the secondary-side coil 212. Specifically, it is preferable that the product of the electric current flowing through the amplification coil 222 and the number of turns of the winding of the amplification coil 222 is set to be less than or equal to the product of the electric current flowing through the secondary-side coil 212 when supplying electric power and the number of turns of the winding of the secondary-side coil 212. With such a configuration, by satisfying standard values of electromagnetic compatibility (EMC) when supplying electric power from the power transmission apparatus 100 to the power reception apparatus 200, standard values of electromagnetic compatibility during operation of the magnetic flux amplifier circuit 220f can also be satisfied, thereby facilitating the circuit design.
As in the power reception apparatus 200 shown in
As in the sixth embodiment, the capacitance C2 of the secondary-side capacitor 214 of the secondary-side resonant circuit 210 may be set, under various predetermined setting conditions and based on the self-inductance L2 of the secondary-side coil 212, the operating frequency f0 (or the operating angular frequency ω0), the coupling coefficients knm and the like, so that the AC power having the operating frequency f0 can be efficiently transferred between the primary-side resonant circuit 110 and the secondary-side resonant circuit 210.
The power reception apparatus 200 according to the seventh embodiment includes, instead of the magnetic flux amplifier circuit 220f (see
When the drive control signal Smd is in the inactive state, the rectifier circuit 242g is driven by the drive circuit 229 to operate as an original synchronous rectifier circuit. In contrast, when the drive control signal Smd is in the active state, the rectifier circuit 242g is driven by the drive circuit 229 to operate in the same manner as the pulse generation circuit 226 (see
Hence, in the seventh embodiment as well, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, in the seventh embodiment, it becomes possible to omit the amplification coil 222, the pulse generation circuit 226 and the DC power supply 228 that together constitute the dedicated magnetic flux amplifier circuit 220f (see
The power reception apparatus 200 shown in
Since no reactive current flows between the terminals of the capacitor 236 of the immittance filter 230 or between the output terminals of the immittance filter 230, the voltage between the terminals of the capacitor 236 or the voltage between the output terminals of the immittance filter 230 is lower than the voltage between the terminals of the secondary-side coil 212. Therefore, with the detection target being the voltage between the terminals of the capacitor 236, the detection can be performed at a lower voltage.
In addition, the voltage between the terminals of the secondary-side coil 212 is usually several hundred volts to several kilovolts when the supply of electric power is performed; therefore, it is necessary to take measures such as protection against very high voltages and the circuit for implementing the measures is complicated.
Moreover, when the load apparatus 240 is in a released state, an overvoltage may occur between the output terminals of the secondary-side resonant circuit 210. Therefore, it is necessary to short-circuit the output terminals of the immittance filter 230 for protection. In the case of the detection target being the voltage between the output terminals of the immittance filter 230, it is necessary to prepare a protection circuit such as a latch circuit. In contrast, in the case of the detection target being the voltage between the terminals of the capacitor 236, even if the output terminals of the immittance filter 230 are short-circuited, the key value and voltage at which the supply of electric power from the power transmission apparatus 100 is not stopped will not be significantly lowered; therefore, the protection circuit can be simplified.
In the above configuration, as described in the seventh embodiment, the capacitance C2 of the secondary-side capacitor 214 of the secondary-side resonant circuit 210 may be set, under various predetermined setting conditions and based on the self-inductance L2 of the secondary-side coil 212, the operating frequency fb (or the operating angular frequency ω0), the coupling coefficients knm and the like, so that the AC power having the operating frequency f0 can be efficiently transferred between the primary-side resonant circuit 110 and the secondary-side resonant circuit 210.
For example, the capacitance C2 of the secondary-side capacitor 214 may be set to be C2=1/(ω02·L2) with respect to the self-inductance L2 of the secondary-side coil 212 so that the operating frequency f0) becomes the resonant frequency of the secondary-side resonant circuit 210. In this case, the coil current generated in the secondary-side coil 212 by the magnetic flux emanating from the primary-side coil 112 due to the standby current is amplified by Q3 times, where Q3 is the Q factor of the secondary-side resonant circuit 210. Accordingly, all of the voltage between the terminals of the secondary-side coil 212, the voltage between the terminals of the capacitor 236 of the immittance filter 230 and the voltage between the output terminals of the immittance filter 230 are amplified. Consequently, even if the magnetic flux generated by the standby current flowing through the primary-side coil 112 is minute, the capability of the detection by the secondary-side detection circuit 260 can be improved and thus the detection can be performed stably. In other words, the standby current in the power transmission apparatus 100 can be reduced; thus, the leakage magnetic flux and loss in the power transmission apparatus 100 can also be reduced.
Therefore, the secondary-side capacitor 214 may be implemented by, for example, a variable capacitor. Further, when not supplying electric power, the capacitance C2 of the secondary-side capacitor 214 may be set to be C2=1/(ω02·L2) with respect to the self-inductance L2 of the secondary-side coil 212 so that the operating frequency f0 becomes the resonant frequency of the secondary-side resonant circuit 210. In contrast, when supplying electric power, the capacitance C2 of the secondary-side capacitor 214 may be set to the capacitance for electric power supply.
As shown in
Moreover, the capacitance C4 of the resonant capacitor 144 may be variable like the capacitance C1 of the primary-side capacitor 114. In this way, electric current flowing through the short-circuited resonant circuit 140 at the time of standby can be reduced; thus, the leakage magnetic flux and loss can also be reduced.
In the ninth embodiment, as in the first embodiment, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, the automatic supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be started faster than in the case of performing a handshake through communication.
In the above-described embodiments, the contactless power supply system includes a pair of a primary-side resonant circuit and a primary-side detection circuit. However, a contactless power supply system may include a plurality of power transmission units each consisting of a primary-side resonant circuit and a primary-side detection circuit.
For example, as shown in
The power transmission apparatus 100J includes a plurality of power transmission units each consisting of one of the primary-side resonant circuits 110 and one of the primary-side detection circuits 120. The power transmission apparatus 100J also includes an AC power supply apparatus 130J. The AC power supply apparatus 130J includes a power supply circuit 132 and a power transmission output circuit 134 for applying electric power to each of the primary-side resonant circuits 110.
The primary-side coils 112 (see
The power supply circuit 132 is a device that converts AC power from an external power supply into DC power. The power transmission output circuit 134 is a device that includes an inverter that converts the DC power supplied from the power supply circuit 132 into AC power having the operating frequency.
The power reception apparatus 200 installed in the vehicle VH includes the secondary-side resonant circuit 210 and the load apparatus 240 (see
A secondary-side coil 212 of the secondary-side resonant circuit 210 is installed at the bottom of the vehicle VH so as to face the primary-side coils 112 of the primary-side resonant circuits 110. Electric power induced in the secondary-side resonant circuit 210 is charged to the battery 244 via the power reception circuit 243, and further used to drive a motor (not shown) or the like.
As described in the first embodiment (see
With the above-described vehicular contactless power supply system according to the present embodiment, it is also possible to achieve the same advantageous effects as achievable with the contactless power supply systems according to the previous embodiments.
As shown in
During traveling of the vehicle VH, when the amplification coil 222 and the secondary-side coil 212 approach the primary-side coil 112P, magnetic coupling occurs between the amplification coil 222 and the primary-side coil 112P and thus the amplification coil 222 generates induced magnetic flux G1. It should be noted that for the sake of facilitating understanding of the technology, those coils which are in the state of generating magnetic flux are hatched in
As shown in
In the present embodiment, as shown in
The arrangement of the primary-side coils 112 is not limited to the arrangement in a straight line along a given direction. For example, as shown in
In addition, although the vehicular contactless power supply system has been described above based on the contactless power supply system according to the first embodiment, the vehicular contactless power supply system is not limited to the contactless power supply system according to the first embodiment; instead, the contactless power supply system according to any one of the above-described embodiments other than the first embodiment can also be applied to the vehicular contactless power supply system.
In the above-described sixth embodiment, as shown in
The circuit configuration of the activation circuit 220k is identical to the circuit configuration of the magnetic flux amplifier circuit 220f illustrated in the sixth embodiment, except that in the activation circuit 220k, the amplification coil 222 is replaced with an activation coil 222k having a different function from the amplification coil 222. The power-transmission-apparatus detecting unit 260k detects the primary-side coil 112 or the power-transmission-apparatus detection section 150 provided near the primary-side coil 112. The configuration of the power transmission apparatus 100 according to the present embodiment is identical to the configuration of the power transmission apparatus 100 illustrated in the sixth embodiment, except that the power transmission apparatus 100 according to the present embodiment further includes the power-transmission-apparatus detection section 150.
In the present embodiment, the power-transmission-apparatus detection section 150 is a two-dimensional code displayed on the surface of the vehicle travel road RS; and the power-transmission-apparatus detecting unit 260k includes a two-dimensional-code reader capable of reading the two-dimensional code. As the two-dimensional code, various two-dimensional codes, such as a QR (registered trademark) code, micro QR code, iQR code or PDF417 code, may be employed. For example, when the power-transmission-apparatus detection section 150 is implemented by a QR code, in the power-transmission-apparatus detecting unit 260k, a detection unit 264k, which is constituted of an imaging unit capable of detecting the QR code, detects the QR code; and the determination circuit 266 determines the presence or absence of the power transmission apparatus 100 based on the detection result of the detection unit 264k. With the above configuration, it is also possible to automatically perform supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. It should be noted that the power-transmission-apparatus detection section 150 is not necessarily exposed on the vehicle travel road RS, and may be disposed in the vehicle travel road RS such that it can be recognized by the power-transmission-apparatus detecting unit 260k.
In response to determination by the determination circuit 266 that there is the power transmission apparatus 100, the drive control signal Smd is set to the active state, thereby causing the drive circuit 229 to drive the activation circuit 220k. Consequently, in the activation circuit 220k, AC current is supplied from the pulse generation circuit 226 to the activation coil 222f, thereby enabling the activation coil 222k to generate magnetic flux changing at the operating frequency 10. As a result, as described in the first embodiment, the magnetic flux generated by the activation coil 222k increases magnetic flux crossing the primary-side coil 112 of the power transmission apparatus 100.
In the primary-side detection circuit 120, the detection signal Sd is switched from the inactive state to the active state in response to detection by the detection circuit 124 of the fact that the primary-side coil voltage VL1 has increased to become higher than or equal to the threshold value Ith. Further, in response to the detection signal Sd being switched to the active state, the capacitance C1 of the primary-side capacitor 114 is set by the C control circuit 126 to the state when supplying electric power, thereby bringing the power transmission apparatus 100 into a state capable of supplying electric power to the power reception apparatus 200. It should be noted that in the present embodiment, the primary-side coil 112 may have no standby current flowing therethrough when the detection signal Sd is in the inactive state. Hence, in the present embodiment as well, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200. Moreover, in the present embodiment, the power reception apparatus 200 can detect the power transmission apparatus 100 without having standby current flow through the power transmission apparatus 100. In addition, although the primary-side detection circuit 120 is configured to detect the change in the primary-side coil voltage VL1 in the present embodiment, the present disclosure is not limited to this configuration. For example, the primary-side detection circuit 120 may alternatively be configured to detect the change in the coil current flowing through the primary-side coil 112, or to detect the magnetic field (or magnetic flux) in the vicinity of the primary-side coil 112 which is changed by the activation circuit 220k.
In the present embodiment, the primary-side resonant circuit 110 may further include an impedance varying element for varying the input impedance of the primary-side resonant circuit 110. The impedance varying element may reduce, when the detected value of the primary-side detection circuit 120 is greater than or equal to a given value, the input impedance of the primary-side resonant circuit 110 to start the supply of electric power. Moreover, standby current may be used to allow the power reception apparatus 200 to more easily detect the power transmission apparatus 100.
In the present embodiment, a variable capacitor element whose capacitance changes according to the control voltage is employed as the primary-side capacitor 114; and the primary-side capacitor 114 constitutes the impedance varying element. However, the impedance varying element may alternatively be constituted of the primary-side capacitor 114b as shown in
In the present embodiment, the activation circuit 220k includes the activation coil 222k, the pulse generation circuit 226 and the DC power supply 228. Alternatively, as shown in
In the present embodiment, it is preferable that the product of the electric current flowing through the activation coil 222k and the number of turns of the winding of the activation coil 222k is set to be less than or equal to the product of the electric current flowing through the secondary-side coil 212 when supplying electric power and the number of turns of the winding of the secondary-side coil 212. With such a configuration, by satisfying the standard value of electromagnetic compatibility (EMC) when supplying electric power from the power transmission apparatus 100 to the power reception apparatus 200, the standard value of electromagnetic compatibility during operation of the activation coil 222k can also be satisfied, thereby facilitating the circuit design.
(1) In the eleventh embodiment, the power-transmission-apparatus detection section 150 is a two-dimensional code displayed on the surface of the vehicle travel road RS; and the power-transmission-apparatus detecting unit 260k includes a two-dimensional-code reader capable of reading the two-dimensional code. As an alternative, the power-transmission-apparatus detection section 150 may be a magnetic marker; and the power-transmission-apparatus detecting unit 260k may include a magnetic-marker detector capable of detecting magnetic flux emanating from the magnetic marker, such as a Hall-effect sensor or a detection coil. Specifically, in this case, in the power-transmission-apparatus detecting unit 260k, the detection unit 264k constituted of the magnetic-marker detector detects the magnetic marker; and the determination circuit 266 determines the presence or absence of the power transmission apparatus 100 based on the detection result of the detection unit 264k. With the above configuration as well, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200.
As another alternative, the power-transmission-apparatus detection section 150 may be an RF tag used for an RFID (Radio Frequency Identifier), or an NFC tag or an IC chip used for NFC (Near Field Communication). RF tags are also called electronic tags, IC tags, wireless tags or RFID tags. In the case of the power-transmission-apparatus detection section 150 being an RF tag, the power-transmission-apparatus detecting unit 260k may employ an RF reader capable of acquiring information attached to the RF tag through wireless communication. RF readers include various devices capable of detecting RF tags, such as RF reader-writers and RF scanners. Otherwise, in the case of the power-transmission-apparatus detection section 150 being an NFC tag or an IC chip, the power-transmission-apparatus detecting unit 260k may employ an NFC reader capable of acquiring information attached to the NFC tag or the IC chip through wireless communication. NFC readers include various devices capable of detecting NFC tags, such as NFC reader-writers and NFC scanners. Specifically, in these cases, in the power-transmission-apparatus detecting unit 260k, the detection unit 264k constituted of the RF reader or the NFC reader detects the RF tag or the NFC tag; and the determination circuit 266 determines the presence or absence of the power transmission apparatus 100 based on the detection result of the detection unit 264k. With the above configuration as well, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200.
As yet another alternative, a part of the power transmission apparatus 100 which is applicable to image detection may be used as the power-transmission-apparatus detection section 150. For example, a part of the power transmission apparatus 100 which is applicable to image detection may be the outline of the primary-side coil 112, a tile for the vehicle travel road RS which includes the primary-side resonant circuit 110, or a figure/geometric pattern for detection which is provided on the surface of the power transmission apparatus 100. In this case, the power-transmission-apparatus detecting unit 260k may include, for example, a camera capable of capturing an image of that part of the power transmission apparatus 10. With the above configuration, the detection unit 264k of the power reception apparatus 200 can detect the power transmission apparatus 100 without increasing the parts count of the power transmission apparatus 100.
Specifically, in the above case, in the power-transmission-apparatus detecting unit 260k, the detection unit 264k constituted of the camera detects that part of the power transmission apparatus 100; and the determination circuit 266 determines the presence or absence of the power transmission apparatus 100 based on the detection result of the detection unit 264k. With the above configuration as well, supply of electric power from the power transmission apparatus 100 to the power reception apparatus 200 can be automatically performed without performing a handshake through communication between the power transmission apparatus 100 and the power reception apparatus 200.
(2) In the above-described ninth embodiment, as shown in
In the above case, the detection circuit 124 can detect the presence or absence of the power reception apparatus 200 by detecting whether there is an increase in the primary-side coil voltage VL1 generated between the terminals of the primary-side coil 112 or an increase in the coil voltage VL4 generated between the terminals of the resonant coil 142. As an alternative, the detection circuit 124 may detect a change in the coil current flowing through the primary-side coil 112 instead of the primary-side coil voltage VL1 or a change in the coil current flowing through the resonant coil 142 instead of the coil voltage VL4. As another alternative, the detection circuit 124 may detect, using a magnetic flux detection element 123 such as a magnetic sensor or coil, a change in the magnetic field (or magnetic flux) in the vicinity of the primary-side coil 112 instead of the primary-side coil voltage VL1 or a change in the magnetic field (or magnetic flux) in the vicinity of the resonant coil 142 instead of the coil voltage VL4.
(3) In the present disclosure, a “resonant state” denotes a state in which the voltage and current generated in the primary-side coil 112 or in the secondary-side coil 212 becomes higher at a specific frequency than the voltage and current outputted from a power supply such as the AC power supply apparatus 130. Alternatively, it denotes a state in which the apparent power generated by the primary-side coil 112 or by the secondary-side coil 212 becomes higher at a specific frequency than the apparent power of the power supply. Alternatively, it denotes a state in which the phase difference between the voltage and current generated in the primary-side coil 112 or generated in the secondary-side coil 212 becomes less at a specific frequency than the phase difference between the voltage and current outputted from the power supply, more particularly becomes zero at a specific frequency. Alternatively, it denotes a state in which voltages in opposite directions are generated at a specific frequency in the primary-side coil 112 and the primary-side capacitor 114 connected in series with the primary-side coil 112 so that the imaginary component of the impedance as viewed from the power supply side is lowered. Furthermore, the voltage of the primary-side coil 112 and the voltage of the primary-side capacitor 114 may cancel each other out so that the imaginary component of the impedance as viewed from the power supply side becomes zero. The “specific frequency” in this case is the drive frequency of the inverter required for applying the AC voltage of the power supply.
(4) In the present disclosure, the “non-resonant state” is equivalent to a state in which no power reception coil exists, and denotes a state in which the magnetic flux density becomes lower than or equal to a safe magnetic flux density. Specifically, the non-resonant state denotes a state in which the magnetic flux density becomes lower than or equal to a reference value (such as ICNIRP) for human exposure that does not affect humans. In the non-resonant state, when there is no power reception coil, the magnetic flux emanating from the primary-side coil 112 may increase, and when there is no power reception side, the magnetic flux is radially generated and the region where the magnetic flux density exceeds the safe reference value may increase. Therefore, safe operation can be secured by placing the power transmission apparatus 100 to the resonant state only when there is the power reception apparatus 200 to which electric power is to be supplied.
The control unit and the control method described in the present disclosure may be realized by a dedicated computer that includes a processor, which is programmed to perform one or more functions embodied by a computer program, and a memory. As an alternative, the control unit and the control method described in the present disclosure may be realized by a dedicated computer that includes a processor configured with one or more dedicated hardware logic circuits. As another alternative, the control unit and the control method described in the present disclosure may be realized by one or more dedicated computers configured with a combination of a processor programmed to perform one or more functions, a memory and a processor configured with one or more dedicated hardware logic circuits. In addition, the computer program may be stored as computer-executable instructions in a computer-readable non-transitory tangible recording medium.
While the above particular embodiments and modifications have been shown and described, it will be understood by those skilled in the art that various further modifications, changes and improvements may be made without departing from the spirit of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-024832 | Feb 2021 | JP | national |
| 2022-010961 | Jan 2022 | JP | national |
The present application is a continuation application of International Application No. PCT/JP2022/003783 filed on Feb. 1, 2022, which is based on and claims priority from both Japanese Patent Application No. 2021-024832 filed on Feb. 19, 2021 and Japanese Patent Application No. 2022-010%1 filed on Jan. 27, 2022. The entire contents of these applications are incorporated by reference into the present application.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2022/003783 | Feb 2022 | US |
| Child | 18235168 | US |
