Patent Grant
10170938
The disclosure of Japanese Patent Application No. 2015-076947 filed on Apr. 3, 2015 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field
The disclosure relates to an electric power receiving device and an electric power transmission device.
2. Description of Related Art
Various types of electric power transmission systems for contactlessly or wirelessly transmitting electric power from an electric power transmission device to an electric power receiving device have been proposed.
The power receiving device includes an electric power receiving unit including a resonance circuit, and a case that houses the power receiving unit, and the resonance circuit includes a power receiving coil and a power receiving capacitor. The power transmission device includes an electric power transmission unit including a resonance circuit, and a case that houses the power transmission unit, and the resonance circuit includes a power transmission coil and a power transmission capacitor.
Generally, the resonance circuit of each of the power receiving unit and the power transmission unit consists of one coil, and one capacitor connected to the coil.
If AC current is passed through the series LC resonance circuit, the voltage of the capacitor and the voltage of the coil vary according to the frequency of the AC current. At this time, the voltage phase of the capacitor and the voltage phase of the coil are in the reversed state. For example, the voltage rises in the coil when the voltage drops in the capacitor, and the voltage drops in the coil when the voltage rises in the capacitor. As a result, during transmission of electric power, the absolute value of a voltage at a connection point of the coil and the capacitor is larger than the absolute values of voltages at the other portions of the resonance circuit.
Since the absolute value of the voltage at the connection point of the coil and the capacitor is large, as described above, the absolute value of the average voltage of the resonance circuit as a whole becomes large.
Therefore, if a member, such as a case, is located around the resonance circuit of each of the power receiving unit and the power transmission unit, a potential difference between the resonance circuit and the case is large. In particular, a potential difference between the connection point of the capacitor and the coil and the case is large.
The disclosure provides a power receiving device having a resonance circuit in which the absolute value of voltage is less likely or unlikely to be large. The disclosure also provides a power transmission device having a resonance circuit in which the absolute value of voltage is less likely or unlikely to be large.
An electric power receiving device according to a first aspect of the disclosure has an electric power receiving unit that contactlessly receives electric power from an electric power transmission device. The power receiving unit includes a first node, a second node, a first capacitor, a first coil, a second capacitor, a second coil, and a third capacitor, and the first capacitor, the first coil, the second capacitor, the second coil, and the third capacitor are sequentially connected in series, between the first node and the second node.
According to the power receiving device as described above, the voltage phase of the first capacitor, second capacitor, and the third capacitor and the voltage phase of the first coil and the second coil are in the reversed state. Therefore, at a point in time at which the voltage rises in the first coil and the second coil, for example, the voltage drops in the first capacitor, second capacitor, and the third capacitor.
If a coil formed by connecting the first coil and the second coil in series is compared with the first coil and the second coil, the amount of voltage rise that occurs in each of the first coil and the second coil is smaller than the amount of voltage rise that occurs in the coil formed by connecting the first coil and the second coil in series. Thus, the amount of voltage rise or voltage drop that occurs in each of the first coil and the second coil can be reduced.
Then, if the first capacitor and the second capacitor are disposed at the opposite ends of the first coil, the absolute value of the voltage of the first coil is less likely or unlikely to be increased. If the second capacitor and the fourth capacitor are disposed at the opposite ends of the second coil, the absolute value of the voltage of the second coil is less likely or unlikely to be increased.
Consequently, the voltage distribution among the first capacitor, first coil, second capacitor, second coil, and the third capacitor indicates relatively low voltages distributed in the power receiving unit as a whole.
An electric power transmission device according to a second aspect of the disclosure includes an electric power transmission unit that contactlessly transmits electric power to an electric power receiving device. The power transmission unit includes a third node, a fourth node, a fourth capacitor, a third coil, a fifth capacitor, a fourth coil, and a sixth capacitor, and the fourth capacitor, the third coil, the fifth capacitor, the fourth coil, and the sixth capacitor are sequentially connected in series, between the third node and the fourth node.
In the power transmission device as described above, the voltage distribution among the fourth capacitor, third coil, fifth capacitor, fourth coil, and the sixth capacitor indicates relatively low voltages distributed in the power transmission unit as a whole.
According to the power receiving device of this disclosure, relatively low voltages are distributed in the power receiving unit as a whole. According to the power transmission device of this disclosure, relatively low voltages are distributed in the power transmission unit as a whole.
Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
The power receiving system 4 includes an electric power receiving device 5, a rectifier 6 connected to the power receiving device 5, and a battery 7 connected to the rectifier 6. The rectifier 6 converts AC power supplied from the power receiving device 5 into DC power, and supplies the DC power to the battery 7. The power receiving device 5 includes an electric power receiving unit 90, and a case 80 that houses the power receiving unit 90. The battery 7 supplies electric power to a converter (not shown). The converter supplies the electric power to an inverter, which in turn supplies the electric power to a rotating electric machine. The rotating electric machine drives vehicle wheels, for example.
The power transmission device 3 includes an electric power transmission unit 40, a frequency converter 11 connected to the power transmission unit 40, and a case 20 that houses the frequency converter 11 and the power transmission unit 40. The frequency converter 11 is connected to an electric power supply 10. The frequency converter 11 adjusts the frequency of AC current supplied from the power supply 10.
In
The resonance frequencies are said to be substantially equal to each other, when a difference between the resonance frequencies of the respective resonance circuits is equal to or smaller than several kHz. If the difference between the resonance frequencies is within this range, electric power can be favorably transmitted between the power transmission unit 40 and the power receiving unit 90.
The Q value of the resonance circuit of the power transmission unit 40 is equal to or larger than 100, and the Q value of the resonance circuit of the power receiving unit 90 is also equal to or larger than 100.
By setting the resonance frequencies and Q values of the power transmission unit 40 and power receiving unit 90 as described above, it is possible to transmit and receive electric power between the power transmission unit 40 and the power receiving unit 90 with high efficiency,
The case 20 includes a metal base plate 22 disposed on the ground, or the like, a metal partition plate 23 provided on an upper surface of the base plate 22, and a lid 24.
The lid 24 includes a resin lid 25 and a metal lid 26. The resin lid 25 is located so as to cover a part of the upper surface of the base plate 22, thereby to form a space in which the power transmission unit 40 is housed. Also, the metal lid 26 is located so as to cover a part of the upper surface of the base plate 22, thereby to form a space in which the frequency converter 11 is housed.
The partition plate 23 is formed on the upper surface of the base plate 22, so as to separate the space in which the power transmission unit 40 is housed, from the space in which the frequency converter 11 is housed.
The frequency converter 11 includes two or more high-voltage devices 29, and the metal lid 26 serves to protect the frequency converter 11, and also prevent noise generated from the respective high-voltage devices 29 from propagating around the power transmission device 3.
The resin lid 25 is formed of a resin material that permits passage of magnetic field and magnetic flux through the lid 25.
The power transmission unit 40 includes a ferrite 21, a coil unit 12 provided on the upper surface of the ferrite 21, and a capacitor unit 13 disposed on the lower surface side of the ferrite 21.
The ferrite 21 includes a peripheral annular core 36 formed by arranging a plurality of split ferrites in an annular shape, and a middle ferrite 35 disposed on the upper surface of the peripheral annular core 36 so as to contact with an inner edge portion of the peripheral annular core 36. The middle ferrite 35 is also formed by arranging a plurality of split ferrites such that they are spaced from each other. The middle ferrite 35 is disposed so as to close an opening of the peripheral annular core 36.
The coil unit 12 includes a coil 17 disposed on the upper surface of the peripheral annular core 36, and a coil 18 disposed on the upper surface of the coil 17.
Each of the coil 17 and the coil 18 is formed by winding a coil wire around a winding axis O1, and the coil 17 and the coil 18 are positioned such that the winding axis O1 is oriented in the vertical direction. Planar spiral coils are employed as the coil 17 and the coil 18.
A wire 31 connected to the frequency converter 11 is connected to one end portion of the coil 17. A wire 33 connected to the frequency converter 11 is connected to a capacitor 16 which will be described below.
The capacitor unit 13 includes a capacitor 14, a capacitor 15, and the capacitor 16. Each of the capacitors 14, 15, 16 is disposed on the lower surface side of the ferrite 21.
More specifically, one electrode of the capacitor 14 is connected to the node 27 (wire 31), and the other electrode of the capacitor 14 is connected to one end portion of the coil 17. The other end portion of the coil 17 is connected to one electrode of the capacitor 15, and the other electrode of the capacitor 15 is connected to one end portion of the coil 18. The other end portion of the coil 18 is connected to one electrode of the capacitor 16. The other electrode of the capacitor 16 is connected to the node 28 (wire 33).
The node 27 is a wire connection point that connects one electrode of the capacitor 14 with the frequency converter 11, and the node 28 is a wire connection point that connects the other electrode of the capacitor 16 with the frequency converter 11.
The case 80 includes a base plate 84 disposed under a floor panel of the vehicle, and a resin lid 85 disposed so as to cover the base plate 84 from below.
The base plate 84 is formed of metal, for example, and functions as a shield. In the case where a shield plate is additionally disposed between the base plate 84 and the floor panel, the base plate 84 may be formed of a resin material.
The resin lid 85 is formed of a material, such as a resin material, through which magnetic field and magnetic flux can permeate. The resin lid 85 is disposed so as to cover the base plate 84 from below. With the resin lid 85 thus mounted on the base plate 84, a space that houses the power receiving unit 90 is formed between the resin lid 85 and the base plate 84.
The power receiving unit 90 includes a ferrite 81, a capacitor unit 9, and a coil unit 8. The ferrite 81 includes a peripheral annular ferrite 82 including a plurality of split ferrites arranged in an annular shape, and a middle ferrite 83 disposed on the lower surface of the peripheral annular ferrite 82. The middle ferrite 83 includes a plurality of split ferrites, and is located so as to close an opening of the peripheral annular ferrite 82.
The coil unit 8 includes a coil 44 disposed on the lower surface of the peripheral annular ferrite 82, and a coil 45 disposed on the lower surface of the coil 44.
Each of the coil 44 and the coil 45 is formed by winding a coil wire around a winding axis O2, and the coil 44 and the coil 45 are positioned such that the winding axis O2 extends in the vertical direction. Planar spiral coils are employed as the coils 44, 45.
The capacitor unit 9 includes a capacitor 41, a capacitor 42, and a capacitor 43. A wire 86 connected to the rectifier 6 is connected to one end portion of the coil 44, and a wire 88 connected to the rectifier 6 is connected to the capacitor 43.
Referring to
The graph of
The AC current I1 supplied to the power transmission unit 40 can be expressed by the following equation (1) as a general expression, and the voltage V1 applied to the power transmission unit 40 can be expressed by the following equation (2).
I1=I01 sin ωt (1)
V1=I01×|Z| sin(ωt+θ) (2)
In the above equations, θ, Z and |Z| are expressed as follows:
θ=tan−1[{ωL17+ωL18−1/(ωC14)−1/(ωC15)−1/(ωC16)}/R]
Z=R+j{ωL17+ωL18−1/(ωC14)−1/(ωC15)−1/(ωC16)}
|Z|=[R2+{ωL17+ωL18−1/(ωC14)−1/(ωC15)−1/(ωC16)}2]1/2
where “I01” is the maximum value of the AC current I1, “ω” is the angular velocity of the AC current, and “Z” is the impedance of the power transmission unit 40. “L17” is the inductance of the coil 17, and “L18” is the inductance of the coil 18. “C14” is the capacitance of the capacitor 14, and “C15” is the capacitance of the capacitor 15. “C16” is the capacitance of the capacitor 16. “R” is the equivalent series resistance (not shown) of the coils 17, 18 and the capacitors 14, 15, 16.
In this embodiment, the power-transmission frequency of the current supplied to the power transmission unit 40 is the resonance frequency of the power transmission unit 40.
Therefore, where f1 denotes the power-transmission frequency (the resonance frequency of the power transmission unit 40), the angular velocity at this time is expressed as ω1=2πf1.
At this time, the impedance of the circuit assumes the minimum value, and |Z| is equal to 0 since the resistance component R is negligibly small in the power transmission unit 40.
Therefore, the following equation is derived from the above-indicated equation (2).
V1=I01×|Z| sin(ωt+θ)=0
Namely, in the power transmission unit 40, the voltages at the opposite ends of the power transmission unit 40 are always equal to 0V.
The case where the current having the power-transmission frequency f1 is passed through the capacitors 14, 15, 16 will be studied. Where the potentials of the electrodes of the capacitors 14, 15, 16 closer to the node 27 are equal to 0V, voltages V14, V15, V16 of the electrodes of the capacitors 14, 15, 16 closer to the node 28 can be expressed by the following equations (3)-(5).
V14=[I01 sin(ω1t−π/2)]/(ω1C14) (3)
V15=[I01 sin(ω1t−π/2)]/(ω1C15) (4)
V16=[I01 sin(ω1t−π/2)]/(ω1C16) (5)
Also, the case where the current having the power-transmission frequency f1 is passed through the coil 17 and the coil 18 will be studied. Where the potentials of the end portions of the coil 17 and the coil 18 closer to the node 27 are equal to 0V, the voltages V17, V18 of the end portions of the coils 17, 18 closer to the node 28 can be expressed by the following equations (6), (7).
V17=ωL17I01 sin(ω1t+π/2) (6)
V18=ωL18I01 sin(ω1t+π/2) (7)
As is apparent from the above-indicated equations (3)-(7), the voltage phase of each of the capacitors 14, 15, 16 is shifted by π from the voltage phase of the coils 17, 18.
Therefore, when the voltage rises in each of the capacitors 14, 15, 16, for example, the voltage drops in each of the coils 17, 18.
The graph shown in
In the example shown in
L17=L18 (8)
Also, the capacitors 14, 16 are formed such that the capacitance C14 of the capacitor 14 is equal to or substantially equal to the capacitance C16 of the capacitor 16. The capacitance C15 of the capacitor 15 is smaller than the capacitance C14, C16, and is set to a half of the capacitance C14, C16. More specifically, the capacitances C14, C15, C16 are set so as to satisfy the following equation (9).
C15=C14/2=C16/2 (9)
Furthermore, the capacitances C14, C15, C16 and the inductances L17, L18 are set so as to satisfy the relationship as indicated by the following equation (10).
2/ω1C14=1/ω1C15=2/ω1C16=ω1L17=ω1L18 (10)
Since each inductance and each capacitance are set, as indicated by Eq. (9) and Eq. (10) above, the potential of the node 27, which is equal to 0V, is lowered to −A1(V), at a joint point of the capacitor 14 and the coil 17. The voltage drops by A1 by means of the capacitor 14.
|A1|=|[I01 sin(ω1t1−π/2)]/(ω1C14)|
Then, the voltage rises to A1 (V), at a connection point of the coil 17 and the capacitor 15. Namely, the voltage rises by 2A1 by means of the coil 17.
|2A1|=|ωL17I01 sin(ω1t1+π/2)| (11)
Then, the potential at a joint point between the capacitor 15 and the coil 18 is lowered to −A1 (V). Namely, the voltage drops by 2A1 by means of the capacitor 15.
|2A1|=|[I01 sin(ω1t1−π/2)]/(ω1C15)|
Then, the potential at a joint point of the coil 18 and the capacitor 16 rises to A1 (V). Namely, the voltage rises by 2A1 by means of the coil 18.
|2A1|=|ωL18 I01 sin(ω1t1+π/2)| (12)
Then, the potential of the node 28 is lowered to 0V. Namely, the voltage drops by A1 by means of the capacitor 16.
|A1|=|[I01 sin(ω1t1−π/2)]/(ω1C16)|
As shown in
The graph of
Where I2 denotes current of the received power, and V2 denotes voltage of the received power, the received current I2 and the received voltage V2 can be expressed by the following equations (13) and (14) as general expressions.
I2=I02 sin ωt (13)
V2=I02×|Z| sin(ωt+θ) (14)
In the above equations, θ, Z and |Z| are expressed as follows:
θ=tan−1[{ωL44+ωL45−1/(ωC41)−1/(ωC42)−1/(ωC43)}/R]
Z=R+j{ωL44+ωL45−1/(ωC41)−1/(ωC42)−1/(ωC43)}
|Z|=[R2+{ωL44+ωL45−1/(ωC41)−1/(ωC42)−1/(ωC43)}2]1/2
where “I02” is the maximum value of the received current I2, “ω” is the angular velocity of the AC current, and “Z” is the impedance of the power receiving unit 90. “L44” is the inductance of the coil 44, and “L45” is the inductance of the coil 45. “C41” is the capacitance of the capacitor 41, and “C42” is the capacitance of the capacitor 42. “C43” is the capacitance of the capacitor 43. “R” is the equivalent series resistance (not shown) of the coils 44, 45 and the capacitors 41, 42, 43.
Since the resonance frequency of the power receiving unit 90 is equal to the resonance frequency of the power transmission unit 40, the impedance of the power receiving unit 90 is minimized if the current having the power-transmission frequency f1 flows through the power receiving unit 90. In the power receiving unit 90, too, the resistance component R is negligibly small; therefore, if the current having the power-transmission frequency f1 flows through the power receiving unit 90, the voltage of the node 46 and node 47 of the power receiving unit 90 becomes equal to 0V.
The case where the current having the power-transmission frequency f1 flows through the capacitors 41, 42, 43 will be studied. Where the potentials of the electrodes of the capacitors 41, 42, 43 closer to the node 46 are equal to 0V, the voltages V41, V42, V43 of the electrodes of the capacitors 41, 42, 43 closer to the node 47 can be expressed by the following equations (15)-(17).
V41=[I02 sin(ω1t−π/2)]/(ω1C41) (15)
V42=[I02 sin(ω1t−π/2)]/(ω1C42) (16)
V43=[I02 sin(ω1t−π/2)]/(ω1C43) (17)
Also, the case where the current having the power-transmission frequency f1 flows through the coil 44 and the coil 45 will be studied. Where the potentials of the end portions of the coil 44 and the coil 45 closer to the node 46 are equal to 0V, the voltages V44, V45 of the end portions of the coils 44, 45 closer to the node 47 can be expressed by the following equations (18), (19).
V44=ωL44I02 sin(ω1t+π/2) (18)
V45=ωL45I02 sin(ω1t+π/2) (19)
As is apparent from the above-indicated equations (15)-(19), the voltage phase of each of the capacitors 41, 42, 43 is shifted by π from the voltage phase of the coils 44, 45.
Therefore, when the voltage rises in each of the capacitors 41, 42, 43, for example, the voltage drops in each of the coils 44, 45.
The graph shown in
In the example shown in
L44=L45 (20)
Also, the capacitors 41, 42 are formed such that the capacitance C41 of the capacitor 41 is equal to or substantially equal to the capacitance C43 of the capacitor 43. The capacitance C42 of the capacitor 42 is smaller than the capacitance C41, C43, and is set to a half of the capacitance C41, C43. More specifically, the capacitances C41, C42, C43 are set so as to satisfy the following equation (21).
C42=C41/2=C43/2 (21)
Furthermore, the capacitances C41, C42, C43 and the inductances L44, L45 are set so as to satisfy the relationship as indicated by the following equation (22).
2/ω1C41−1/ω1C42=2/ω1C43=ω1L44=ω1L45 (22)
Since each inductance and each capacitance are set, as indicated by Eq. (21) and Eq. (22) above, the potential of the node 46, which is equal to 0V, is lowered to −A2 (V), at a joint point of the capacitor 41 and the coil 44. Namely, the voltage drops by A2 in the capacitor 41.
|A2|=|[I02 sin(ω1t2−π/2)]/(ω1C41)|
Then, the voltage rises to A2 (V), at a connection point of the coil 44 and the capacitor 42. Namely, the voltage rises by 2A2 by means of the coil 44.
|2A2|=|ωL44I02 sin(ω1t2+π/2)| (23)
Then, the potential at a joint point of the capacitor 42 and the coil 45 is lowered to −A2 (V). Namely, the voltage drops by 2A2 by means of the capacitor 42.
|2A2|=|[I02 sin(ω1t2−π/2)]/(ω1C42)|
Then, the potential at a joint point of the coil 45 and the capacitor 43 rises to A2 (V). Namely, the voltage rises by 2A2 by means of the coil 45.
|2A2|=|ωL45I02 sin(ω1t2+π/2)| (24)
Then, the potential of the node 47 is lowered to 0V. Namely, the voltage drops by A2 by means of the capacitor 43.
|A2|=|[I02 sin(ω1t2−π/2)]/(ω1C43)|
As shown in
The operation and effect of the power receiving unit and the power transmission unit according to the above embodiments will be described, using an electric power transmission unit 50 and an electric power receiving unit 60 as comparative examples.
The resonance frequency of the power transmission unit 50 is equal to the resonance frequency of the power transmission unit 40 shown in
Therefore, where C52 denotes the capacitance of the capacitor 52, and L53 denotes the inductance of the coil 53, the following equations (25) and (26) are satisfied.
L53=L17+L18 (25)
1/C52=1/C14+1/C15+1/C16 (26)
Then, in
Then, the voltage of the electrode of the capacitor 52 closer to the node 51 is 0V, and a voltage −B1 at a connection point of the capacitor 52 and the coil 53 can be expressed by the following equation (27).
−B1=−|[I01 sin(ω1t1−π/2)]/(ω1C52)| (27)
Then, the voltage rises by B1 in the coil 53.
B1=|ωL53I01 sin(ω1t1+π/2)| (28)
Here, |A1| shown in
According to the above-indicated equations (11) and (12), |A1| can be expressed as follows.
|A1|=|ωL17I01 sin(ω1t1+π/2)|/2
|A1|=|ωL18I01 sin(ω1t1+π/2)|/2
Here, according to the above-indicated equations and Eq. (25) and Eq. (28), the following equation (29) is established.
|B1|=2×|A1| (29)
Thus, according to the power transmission unit 40 of this embodiment, the maximum value of the absolute value of the voltage can be reduced to be lower than that of the power transmission unit 50 according to the comparative example. Furthermore, as is apparent from
Thus, in
Furthermore, since the maximum value of the absolute value of the voltage developed in the coil unit 12 can be reduced, a potential difference between the coil unit 12, and the ferrite 21 and base plate 22 provided around the coil unit 12, can also be reduced.
In particular, since the capacitance C15 of the capacitor 15 is made smaller than the capacitances C14, C16 of the other capacitors 14, 16, the voltage drop (voltage rise) that occurs in the capacitor 15 is larger than the voltage drop (voltage rise) that occurs in the capacitors 14, 16.
With this arrangement, even if the voltage rises (drops) largely in the coil 17, the voltage drops (rises) largely in the capacitor 15, so that the average voltage of the power transmission unit 40 can be prevented from being large.
Furthermore, the inductance L17 of the coil 17 is made equal to or substantially equal to the inductance L18 of the coil 18, so that the voltage distribution that appears in the power transmission unit 40 becomes symmetrical about the capacitor 15. In this manner, the average voltage of the power transmission unit 40 can be made close to 0.
In this connection, the inductance L17 and the inductance L18 are said to be substantially equal to each other, when a difference between the inductance L17 and the inductance L18 is equal to or smaller than 5% of the inductance L17. If the difference in the inductance is within the above-indicated range, the average voltage of the voltage distribution in the power transmission unit 40 becomes approximate to 0.
Both of the resonance frequency of the power receiving unit 60 and the resonance frequency of the power receiving unit 90 are equal to or substantially equal to the power-transmission frequency f1.
Therefore, where C62 denotes the capacitance of the capacitor 62, and L63 denotes the inductance of the coil 63, the following equations (30) and (31) are satisfied.
L63=L44+L45 (30)
1/C62=1/C41+1/C42+1/C43 (31)
Furthermore, since the resonance frequency of the power receiving unit 60 is equal to the power-transmission frequency f1, the potentials at the node 61 and the node 64 are equal to 0V, as shown in
Then, a voltage −B2 at a connection point of the capacitor 62 and the coil 63 can be expressed by the following equation (32). The time shown in
−B2=−|[I02 sin(ω1t2−π/2)]/(ω1C62)| (32)
Then, the voltage rises by B2 in the coil 63.
B2=|ωL64I02 sin(ω1t2+π/2)| (33)
Here, the graph shown in
According to the above-indicated equations (23) and (24), |A2| can be expressed as follows.
|A2|=|ωL44I02 sin(ω1t2+π/2)|/2
|A2|=|ωL45I02 sin(ω1t2+π/2)|/2
Here, according to the above-indicated two equations and Eq. (30) and Eq. (33), the relationship between |B2| and |A2| can be expressed by the following equation (34).
|B2|=2×|A2| (34)
As is apparent from this equation (34), the maximum value of the absolute value of the voltage developed in the power receiving unit 90 according to this embodiment can be reduced to be lower than the absolute value of the maximum value of the voltage of the power receiving unit 60 according to the comparative example. As a result, according to the power receiving unit 90 of this embodiment, potential differences between various members disposed around the power receiving unit 90, and the power receiving unit 90, can be reduced.
Furthermore, as is apparent from
In particular, since the capacitance C42 of the capacitor 42 is set to be smaller than the capacitances C41, C43 of the other capacitors 41, 43, the voltage drop (voltage rise) that occurs in the capacitor 42 is larger than the voltage drop (voltage rise) that occurs in the capacitors 41, 43.
With this arrangement, even if the voltage rises largely in the coil 44, the voltage drops largely in the capacitor 42, so that the average voltage of the power receiving unit 90 as a whole can be prevented from being large.
Furthermore, the inductance L44 of the coil 44 is made equal to or substantially equal to the inductance L45 of the coil 45, so that the voltage distribution that appears in the power receiving unit 90 becomes symmetrical about the capacitor 42. In this manner, the average voltage of the power receiving unit 90 as a whole can be made close to 0.
In the power transmission unit 40 shown in
Furthermore, while the capacitance of each capacitor is set as indicated in the above equation (9), this arrangement is not an essential arrangement.
Here, L117 denotes the inductance of the coil 117, and L118 denotes the inductance of the coil 118.
Then, the inductances L117, L118 of the coils 117, 118 are set such that L117>L17=L18>L118. The graph of
Here, the voltage distribution shown in
Therefore, the amount of voltage rise (A3+A4) that occurs in the coil 117 is smaller than the amount of voltage rise (B1) that occurs in the coil 53.
Further, since the voltage drops by means of the capacitor 114 connected to the coil 117, the voltage of the coil 117 as a whole is low. Therefore, |A3| and |A4| are far smaller than |B1|.
Similarly, since the voltage rises in the coil 118, and the voltage drops in the capacitor 115, |A6| of the voltage A6 shown in
Thus, with the capacitor, coil, capacitor, coil, and the capacitor sequentially connected in series, between the node 27 and the node 28, the maximum value of the absolute value of the voltage developed in the power transmission unit can be reduced, and the average voltage of the power transmission unit can be reduced.
In the power receiving unit, too, it is not essential that the inductance of the coil 44 is made equal to the inductance of the coil 45, and that the capacitance of the capacitor 42 is made larger than the capacitances of the capacitor 41 and the capacitor 43.
Namely, when the power receiving unit is configured such that the capacitor 41, coil 44, capacitor 42, coil 45, and the capacitor 43 are sequentially connected in series, between the node 46 and the node 47, the average voltage and the absolute value of the maximum value of the voltage can be reduced, as compared with the case where one coil and one capacitor are connected in series with each other.
While the embodiments of the disclosure and their modified examples have been described above, the matters described herein are merely exemplary in all aspects, and not restrictive. The technical scope of the disclosure is defined by the appended claims, and is intended to include all changes or modifications within the range of the claims and equivalents thereof.
The present disclosure can be applied to electric power receiving devices and electric power transmission devices.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-076947 | Apr 2015 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20130127409 | Ichikawa | May 2013 | A1 |
| 20130193749 | Nakamura et al. | Aug 2013 | A1 |
| 20150008877 | Ichikawa et al. | Jan 2015 | A1 |
| 20150049517 | Yan et al. | Feb 2015 | A1 |
| Number | Date | Country |
|---|---|---|
| 104377961 | Feb 2015 | CN |
| 2013-080785 | May 2013 | JP |
| 2013-110822 | Jun 2013 | JP |
| 2013-126327 | Jun 2013 | JP |
| 2013-146148 | Jul 2013 | JP |
| 2013-146154 | Jul 2013 | JP |
| 2013-154815 | Aug 2013 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20160294222 A1 | Oct 2016 | US |
