The invention relates to a method for charging by magnetic coupling comprising the functions of electrical charging and of communicating information originating from a portable device in order to control the charging. The invention also relates to a charging bench able to implement such a method.
The field of the invention is that of inductive charging by an optionally portable device, referred to as the “primary” device, which device is used to charge or recharge one or more portable electronic devices, for example mobile phones, USB keys, MP3 players, smartphones, GPS devices, etc., which devices are collectively referred to as the “secondary” device.
Primary inductive charging devices are recent developments. The use of inductive charging is becoming more widespread, since, because there is no need for a specific connection interface, it enables wireless charging and can be adapted to many applications including, in particular, a “charging bench” surface which is used to simultaneously recharge a number of portable devices. Furthermore, it enables charging to be combined with a billing function for billing for the electrical power supplied. Inductive charging is becoming a universal charging standard.
Inductive charging makes use of the electrical phenomena of magnetic coupling between two windings, that of the primary device and that of the secondary device, which enables the electromagnetic transfer of voltage. An AC current in the winding of the primary device produces a variable magnetic field, the field lines of which transect the winding of the secondary device. This transection of the secondary winding by field lines of varying intensity induces a current in this winding. The voltage created by this current can then be used to power the secondary device or to charge its battery. The efficiency of the transfer depends on the quality of the coupling between the two windings.
Inductive charging requires a communication function that is specific to it, in order to control charging based on reception, by the primary device, of information relating to the charge level, the charging rate, or the bill for the power supplied. The primary device then processes the information in order to deduce therefrom possible actions to take: stopping of the charging, whether completely or temporarily, triggering of a billing process, etc.
Many ways of improving inductive charging have been provided recently, such as those published in patent documents U.S. 2010/0066305, U.S. 2011/0025265 or U.S. 2011/0285348.
Document U.S. 2010/0066305 in particular describes various operations that must be carried out in order to charge a secondary device, especially: placing the winding of the secondary device opposite that of the primary device; providing control and contactless communication functions in order to monitor charging of the secondary device; and stopping the charging once it is complete. One of the drawbacks of this type of device lies in the need to stop the charging in order to carry out the indispensible steps of communication and in order, in particular, to verify the charge level of the secondary device. The charging is interrupted so that the communication can be transmitted without interference or parasitic noise.
Document U.S. 2011/0025265 describes a primary device equipped, in addition to the winding provided for the electrical charging, with a second antenna for proximity wireless communication with the secondary device, and a secondary device also equipped with a second antenna. This second antenna is mainly dedicated to communication between the primary device and the secondary device. Nevertheless, during the communication phase, the charging is stopped, otherwise this charging interferes with the communication via harmonic noise. In addition, the constraint imposed on the secondary device, namely the use of a specific second antenna, deprives the wireless charger of its universal nature.
As for document U.S. 2011/0285348, it relates to improvements to the manufacture of the winding of the secondary device; it is formed by molding in one of the constituent layers of the secondary device. A winding molded in this way has two advantages: durability and thinness.
However, these devices do not enable, in good conditions, charging of the secondary device by the primary device simultaneously with communication between these two devices. Such simultaneity allows the charge level to be monitored in real time and the power emission to be decreased or stopped as soon as the secondary device signals that it is fully charged.
In these prior-art devices, the charging flux and the communication flux combine together as an amplitude modulation. The modulation index, which expresses the ratio of the amplitude of the information to the amplitude of the carrier, remains extremely small, about 1%, because the emitting antennas exhibit strong resonance, in order to increase their quality factor, and continuous emission. This small modulation index makes decoding the communication difficult and uncertain. In addition, the communication interferes with the charging flux, decreasing resonance between the two windings and therefore decreasing the efficiency of the transmission of energy between them.
The invention aims to overcome these drawbacks by separating the two types of flux for the portable device to be charged, i.e. the inductive charging magnetic flux and the communication flux concerning this charging, via reversible switching of coils between charging and communication modes.
More precisely, the present invention relates to a method for charging via magnetic coupling performing the functions of electrical charging of a portable electronic device to be charged, called the secondary device, by a charging device or bench, called the primary device, comprising at least two coils, and of communicating information originating from the secondary device to the primary device. In this method, the secondary device is detected then located via the emission of a test signal by at least one coil of the primary device, and the reception, in return, of a signal carrying information data by at least one coil of the primary device. The amplitude of the signal or signals received are then compared to at least one reference threshold in order to determine, in a selection phase, the coil of the primary device closest to the secondary device to switch into a charging mode, and the coil of the primary device, located proximate this charging coil, to switch into a mode for communicating information data so as to actuate instructions contained in these data.
Thus this method decouples the charging flux and the communication flux over at least two coils of the primary device, thereby making it possible for the secondary device to transmit instructions to the charger during charging without the charging interfering with this communication. The index of the amplitude modulation is greatly increased, becoming about 25%.
According to preferred embodiments:
The invention also relates to a charging bench able to implement this method. Such a charging bench comprises means for supplying electrical power, a surface for holding portable devices (secondary devices) to be charged, an array of coils consisting of at least two coils, at least one microcontroller for processing information data originating from at least one device to be charged (secondary device), at least one charging regulator, and mode selecting means connected, for each coil, to the microcontroller and the regulator in a circuit.
According to certain preferred embodiments:
Other particulars, features and advantages of the present invention will become apparent on reading the following nonlimiting description, given with reference to the appended figures, which respectively show:
a and 2b, a top view of the three coils in the exemplary charging bench according to
a to 3c, signal amplitude graphs showing the modulation index of the communication received by the two end coils of the bench according to
The schematic view in
A portable device 5 to be charged (the secondary device 5) and more particularly a mobile phone 5 in the example, is placed on the upper side 3 of this charging bench (the mobile phone 5 is shown a distance from the bench for the sake of clarity). Such a mobile phone 5 comprises a winding 6 intended to receive the electrical charging, and a ferrite protective screen 7 for protecting its electronics from the surrounding magnetic fields.
One of the coils, the coil Bb in the illustrated example, is selected to emit the magnetic charging flux 2 toward the mobile phone 5. The selection is carried out, according to the invention, via emission of a series of pulses by one of the coils and comparison of return signals with a reference threshold (see below, with reference to
The overlap of the coils advantageously allows, as illustrated by the top view of the charging bench 1 in
When no device is present on the charging bench 1, the communication zones a2, b2 and c2 of each of the coils Ba, Bb and Bc, are smaller than the charging zones a1, b1 and c1. When a secondary device 5 is placed on the charging bench 1 and is equipped with ferrites—for example the mobile phone 5 (FIG. 1)—the communication zones a2, b2 and c2 enlarge. As illustrated in
More precisely, the ferrites 7 increase the coupling between the secondary device 5 and the coils of the charging bench 1. Thus they preferably redirect the magnetic lines containing the data emitted by the second device 5 toward the charging bench 1. Advantageously, the invention employs the formation of such a zone 20 to produce flux for communication between the second device 5 and any coil in the charging bench 1, in particular at least one of the coils other than the charging coil.
The increase in extent of the communication zone results in the increase in the modulation index produced by the charging bench 1 when a communication flux is transmitted to said charging bench 1. The graphs in
When no secondary device 5 is placed on the charging bench 1 (
In the case where a secondary device 5 to be charged is placed on the charging bench 1 on the side of one of the end coils, on the side of the coil Ba in the example (
The amplitude of the reception signal 51 of the coil Ba increases by about 250% due to the concentration of flux when the secondary device 5 comprises ferrites 7, as in the example illustrated in
When the secondary device 5 is placed substantially in the center of the charging bench 1, in other words nearer the central coil Bb than the other end coils, these two end coils Ba and Bc receive communication signals, 61 and 62 respectively, of the same order of magnitude (cf.
Under these conditions, it would appear that a comparison between the amplitudes of the carrier signals 51 and 52, and/or between the communication signals 61 and 62, would provide an estimation of the location of the secondary device 5 between the end coils Ba and Bc. The invention thus allows a secondary device 5 to be located after it has been detected via amplification of the carrier signals 51 and 52. The diagram of
The partial overlap of the coils B1, B2, B3, . . . , Bn, arranged in two parallel planes, is desirable for reasons of decoupling, as mentioned above. During the detection phase, regularly distributed coils, one coil in three in the example illustrated, namely coils B2 and B5 in
When a coil, the coil B3 in the example illustrated, receives a signal 83 with an amplitude higher than said threshold, a secondary device 5 to be charged is detected. If a number of coils, for example B3 and B4, receive signals 83 and 84 with an amplitude higher than said threshold, comparison of these amplitudes allows the location of the secondary device 5 to be charged to be deduced directly. In the example, the amplitude of the signal 83 is higher than that of the signal 84, and the secondary device 5 is nearer the coil B3 than the coil B4.
The coil B3 located nearest the secondary device 5 is then switched to charging mode, and the neighboring coil B4 is then switched to communication mode. Switching between modes is carried out by communication/charging mode selector circuits, as described below with reference to the diagram of
Such a circuit 30 comprises a microcontroller 31 for processing information data originating from at least one secondary device 5; a charging regulator 32; a multipath communication selector 33 the multiple outputs 33s of which are connected to one end E1, E2, . . . , En, of each coil B1, . . . , Bn, and the input 33e of which is connected to the microcontroller 31; and a multipath charging selector 34 the multiple outputs 34s of which are connected to the other end E′1, E′2, . . . , E′n, of each coil B1, . . . , Bn and the input 34e of which is connected to the charging regulator 32. The ends E1, E2, . . . , En of the coils are also connected to the microcontroller 31 via amplifiers A1, A2, . . . , An fitted on direct connections L1, L2, . . . , Ln. These ends E1, E2, . . . , En, are also grounded “T” through capacitors C1, C2, . . . , Cn. These amplifiers and capacitors contribute to balanced operation of the circuit 30.
Each coil is able to function in a mode for communicating information data originating from the secondary device 5 to be charged, by way of connection to the microcontroller 31 via the selector 33, or in a mode for inductive charging via transmission of an energy flux, by way of connection to the regulator 32 via the selector 34.
The flow chart of
The microcontroller 31 (
In the detection step 100, the voltages VB1, VB3, VB4, VB6, . . . , VBn and VB(n+2) are compared to the detection threshold K3.Vi. In the example, the voltages of the coils Bn and B(n+2) are higher than the threshold K3.Vi (result 100′), thereby indicating that a secondary device 5 is detected opposite these coils. In practice, depending on the size of the secondary devices 5 to be charged and of the network of coils, the number of coils concerned per secondary device 5 detected is in general limited to two or three juxtaposed coils. If no voltage VB3, VB4, VB6, . . . , VBn and VB(n+2) is higher than the threshold K3.Vi, the detection step 100 is reinitialized.
In phase (II) of locating the secondary device 5 to be charged, comparison of the levels of the signals received, measured as voltages VBn and VB(n+2), with the detection thresholds K1.Vi and K2.Vi, allows the device 5 to be charged to be located relative to the coils Bn, B(n+1) and B(n+2) and then (phase III) operating modes to be selected, i.e. either the charging mode or the communication mode, for at least two of these coils.
To do this, it is hypothesized that the device 5 is located nearest the coil Bn via its voltage level (step “H1”). To verify this hypothesis, the voltage VBn is compared to the upper threshold K1.Vi in the comparison step 101. If the voltage VBn is higher than the upper limit K1.Vi, it means that the secondary device 5 is closer to the coil Bn than any other coil: the coil Bn is switched into secondary device 5 charging mode (step 102). Furthermore, the coil B(n+1), which is closer to the secondary device 5 than the coil B(n+2) because it is closer to the coil Bn, is switched into communication mode (step 103). If the communication flux is not received by the coil Bn (step 104), the step of comparison to the significant threshold K3.Vi (step 100) is reinitialized.
If the voltage VBn is lower than the upper threshold K1.Vi, the same comparison with the threshold K1.Vi is then carried out for the voltage B(n+2) (step 101′). In the case where the voltage VB(n+2) is higher than the threshold K1.Vi, it is deduced therefrom that the secondary device 5 to be charged is closer to the coil B(n+2) than the other coils: the coil B(n+2) is switched into charging mode (step 102′) and the coil B(n+1)—closer to the secondary device 5 to be charged than the coil Bn because it is closer to the coil B(n+2)—is switched into communication mode (step 103′). If the communication flux is not received by the coil B(n+1) (step 104′), the step of comparison to the significant threshold K3.Vi (step 100) is reinitialized.
In the contrary case where the voltage VB(n+2) is lower than the threshold K1.Vi, a double comparison is carried out (step 101″) with the lower detection threshold K2.Vi, in order to determine whether one of the voltages VB(n+2) or VBn is higher than the threshold K2.Vi. In the case where one of the voltages VB(n+2) or VBn is higher than the threshold K2.Vi, whereas the other is not, the coil B(n+1) is considered to be closer to the secondary device 5 to be charged and is switched into charging mode (step 102″). One of the adjacent coils or both, Bn and/or B(n+2) is or are switched into communication mode (step 103″).
The invention is not limited to the embodiments described and shown. Thus:
Number | Date | Country | Kind |
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1253357 | Apr 2012 | FR | national |