JP5842106B2 - Contactless power supply system - Google Patents

Description

  The present invention relates to a non-contact power supply system that supplies power to a power receiving device in a non-contact manner.

  Conventionally, there is a non-contact power feeding system that feeds power from a power feeding device to a power receiving device in a contactless manner (see, for example, Patent Document 1). In the conventional non-contact power feeding system, the power receiving device is installed at a fixed position in the power feeding device when performing power feeding. Only in this state, power is supplied from the power supply apparatus to the power reception apparatus.

  In recent years, in order to further improve the convenience of users, a so-called free-layout type that can supply power to the power receiving device only by installing the power receiving device at an arbitrary position on the upper surface (power feeding surface) of the power feeding device. A non-contact power feeding system has been studied (see, for example, Patent Document 2).

  As shown in FIG. 10A, a plurality of primary coils L <b> 1 are arranged along the power supply plate 6 in the power supply device 10 in the free layout type non-contact power supply system. Further, the power receiving device 30 is provided with a secondary coil L2. In FIG. 10 (a), the secondary coil L2 faces the primary coil L1. The primary coil L1 is excited at the operating frequency f1. An induced current is generated in the secondary coil L2 based on a change in magnetic flux from the excited primary coil L1. This induced current is the output power of the power receiving device. In this manner, electric power is supplied from the power feeding device 10 to the power receiving device 30 in a non-contact manner using electromagnetic induction.

JP 2003-204637 A JP 2008-5573 A

  In the conventional non-contact power feeding system (non-free layout type system), as shown in FIG. 11, the operating frequency f1 of the primary coil L1 is the resonance system when the secondary coil L2 faces the primary coil L1. Is set to coincide with the resonance frequency fr. This resonance frequency fr is the resonance frequency of the secondary coil L2. In the conventional non-contact power feeding system, the power receiving device is installed at a fixed position with respect to the power feeding device, so that the secondary coil L2 can always face the primary coil L1 during power feeding. Therefore, the maximum output power W1 can be obtained in the power receiving device 30 by setting the operating frequency f1 to the resonance frequency fr.

  On the other hand, in the above-described free layout type non-contact power feeding system, if the power feeding plate 6 of the power feeding device 10 is used, it is not necessary to install the power receiving device 30 at a specific position. Therefore, in this system, as shown in FIG. 10B, the secondary coil L2 may be positioned between two primary coils L1 adjacent to each other. In a state where the secondary coil L2 is directly opposed to the primary coil L1, the leakage inductance Le is minimum. And the leakage inductance Le increases as the secondary coil L2 shifts from the directly facing position along the power feeding plate 6.

  It is known that the resonance frequency fr decreases as the leakage inductance Le increases. Therefore, as shown by the arrow in FIG. 11, the resonance frequency fr decreases with the resonance system according to the positional deviation of the secondary coil L2 with respect to the primary coil L1.

  For this reason, the output power W2 when the secondary coil L2 is located between the two primary coils L1 is significantly lower than the output power W1 when it is in the directly-facing position. As described above, in the free layout type non-contact power feeding system, the output power in the power receiving device 30 varies greatly depending on the installation position of the power receiving device 30, and it is difficult to secure stable output power.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a non-contact power feeding system capable of ensuring stable output power regardless of the position of a secondary coil.

In order to solve the above problems, a contactless power feeding system according to the present invention is a power feeding system in which a plurality of primary coils that generate alternating magnetic flux by being supplied with an alternating current that vibrates at an operating frequency are disposed along a power feeding surface. A power receiving device having a secondary coil that generates an induced power based on an alternating magnetic flux from the primary coil and supplies the power to a load in a state where the device is installed on the power feeding surface, In a non-contact power feeding system using a resonance phenomenon in a secondary coil, a coil position determination unit that determines a position of the secondary coil with respect to the primary coil, and a value of a resonance frequency in the secondary coil with respect to the operating frequency are switched. a switching circuit, based on a determination result of the coil position determination unit, a control to a value corresponding to the resonant frequency to the operating frequency through said switching circuit Comprising a road, wherein the coil position determination unit is provided in an each of the primary coil, and a light emitting element for emitting light to the power receiving device in the feeding plane, provided corresponding to said light emitting element In addition, based on the number of light receiving elements that detect the presence of reflected light among the light receiving elements, the light receiving elements that detect the presence or absence of reflected light when the light is emitted to the power receiving device on the power supply surface, a determination unit for determining position relative to the primary coil of the secondary coil, Ru comprising a.

  Further, in the above configuration, the switching circuit is connected in series to the secondary coil, and a plurality of capacitors and switching elements connected in series are provided, and each set is connected in parallel. It is preferable to switch the value of the resonance frequency with respect to the operating frequency through switching of the on / off state.

  According to the present invention, stable output power can be ensured regardless of the position of the secondary coil in the non-contact power feeding system.

The block diagram which shows the structure of the non-contact electric power feeding system in 1st Embodiment. The perspective view of the electric power feeder and power receiving device in 1st Embodiment. The block diagram which shows the structure of the resonance system switching circuit in 1st Embodiment. The table | surface which showed the on-off state of each photoMOS according to the position of the secondary coil L2 in 1st Embodiment. (A) a top view showing a directly facing position of the secondary coil L2 in the first embodiment, (b) a top view showing a first position of the secondary coil L2, and (c) a second of the secondary coil L2. The top view which shows a position. The graph which showed the output (resonance system) of the power receiving apparatus according to the position of the secondary coil L2 in 1st Embodiment. The block diagram which shows the structure of the non-contact electric power feeding system in 2nd Embodiment. The top view of the presence detection circuit in 2nd Embodiment. The fragmentary sectional view of the electric power feeder and electric power receiving apparatus in 2nd Embodiment. In the background art, (a) a partial cross-sectional view of the power feeding device and the power receiving device when the secondary coil L2 is in the directly-facing position, and (b) power feeding when the secondary coil L2 is at the center position between the primary coils L1. The fragmentary sectional view of a device and a receiving device. The graph which showed the resonance system when the secondary coil L2 in background art faces the primary coil L1, and the secondary coil L2 exists in the center position between both the primary coils L1.

(First embodiment)
Hereinafter, a first embodiment embodying the non-contact power feeding system of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the non-contact power feeding system includes a power feeding device 10 and a power receiving device 30. In this example, the power receiving device 30 is built in the mobile terminal 40. Hereinafter, specific configurations of the power feeding device 10 and the power receiving device 30 will be described.

(Power supply device)
As shown in FIG. 2, the power supply apparatus 10 has a flat housing 5. On the upper surface of the housing 5, a power supply plate 6 on which the mobile terminal 40 is installed is formed. In the housing 5, 36 primary coils L <b> 1 are arranged over the entire area of the power feeding plate 6. The primary coils L1 are arranged in a matrix of 6 rows × 6 columns on the power supply plate 6.

  As shown in FIG. 1, the power supply apparatus 10 includes a single common unit 11 and a plurality of (36 in this example, the same number as the primary coil L1) power supply units 15 respectively connected to the common unit 11; Is provided.

  The common unit 11 includes a power supply circuit 13, a common control circuit 12, and a memory 14. The power supply circuit 13 converts AC power from an external power source into an appropriate DC voltage, and supplies the DC voltage as operating power to each power supply unit 15 and the common unit 11. The memory 14 stores an ID code unique to the power receiving device 30.

The common control circuit 12 is composed of a microcomputer and controls the power supply device 10 through various command signals to each power supply unit 15.
The power supply unit 15 includes a unit control circuit 19, an excitation drive circuit 16, a voltage detection circuit 17, and a primary side communication circuit 18.

  Both ends of the primary coil L1 are connected to the excitation drive circuit 16. A capacitor C1 is connected between one end of the primary coil L1 and the excitation drive circuit 16. Further, both ends of the primary side communication coil L3 are connected to the primary side communication circuit 18.

  When the unit control circuit 19 receives a command signal for requesting power supply from the common control circuit 12, the unit control circuit 19 controls the excitation drive circuit 16. The excitation drive circuit 16 generates an alternating current having an operating frequency f1 through the control by the unit control circuit 19, and supplies it to the primary coil L1 and the capacitor C1. Thereby, the primary coil L1 is excited. At this time, the magnetic flux from the primary coil L1 changes.

  The voltage detection circuit 17 is connected to the primary coil L1. The voltage detection circuit 17 detects the voltage of the primary coil L 1 and outputs the detection result to the unit control circuit 19.

  The unit control circuit 19 supplies a high-frequency current to the primary coil L1, and detects the presence or absence of an object around the primary coil L1 based on the detection result of the voltage detection circuit 17 at that time.

  Specifically, when the secondary coil L2 is present in the direction of the magnetic flux of the primary coil L1, the excited primary coil L1 is magnetically coupled to the secondary coil L2, thereby increasing the impedance viewed from the primary coil L1. To do. For this reason, the voltage of the primary coil L1 falls.

  Based on the detection result of the voltage detection circuit 17, the unit control circuit 19 calculates the degree of magnetic coupling of the secondary coil L2 to the primary coil L1 as the presence detection level. When the distance between the secondary coil L2 and the primary coil L1 in the axial direction of the primary coil L1 is constant, the presence detection level is determined when the secondary coil L2 and the primary coil L1 are viewed from this axial direction. It becomes a value according to the overlapping area. The presence detection level is calculated as “0.0” when the secondary coil L2 does not overlap the primary coil L1 at all, and when the secondary coil L2 overlaps the entire area of the primary coil L1, “ 1.0 ".

  When the unit control circuit 19 determines that an object is present around the primary coil L1 based on the calculated presence detection level, the unit control circuit 19 outputs an information signal including the presence detection level to the primary side communication circuit 18. The primary side communication circuit 18 modulates the information signal and wirelessly transmits the modulated signal via the primary side communication coil L3.

  Further, when the unit control circuit 19 determines that an object is present around the primary coil L1 based on the presence detection level, the unit control circuit 19 outputs the presence detection level to the common control circuit 12. Upon receiving the presence detection level from the unit control circuit 19, the common control circuit 12 generates an ID request signal through the unit control circuit 19 and outputs the generated signal to the primary side communication circuit 18. The primary side communication circuit 18 modulates the ID request signal and wirelessly transmits the modulated signal via the primary side communication coil L3.

  When receiving the ID signal from the power receiving device 30 using electromagnetic induction, the primary side communication coil L3 outputs the received signal to the primary side communication circuit 18. The primary communication circuit 18 demodulates the ID signal and outputs the demodulated signal to the common control circuit 12 through the unit control circuit 19. The common control circuit 12 collates the ID code included in the ID signal with the ID code stored in the memory 14. When the common control circuit 12 determines that ID code verification has been established, the common control circuit 12 performs power feeding as described above, assuming that the object is the normal power receiving device 30.

(Power receiving device)
As shown in FIG. 1, the power receiving device 30 includes a rectifier circuit 31, a DC / DC converter 35, a secondary side communication circuit 32, a secondary side control circuit 33, a memory 34, and a resonance system switching circuit 41. And a switch drive circuit 38.

  The secondary side communication circuit 32 is connected to both ends of a secondary side communication coil L4. The secondary coil L2 induces a current based on a change in magnetic flux from the primary coil L1. The rectifier circuit 31 rectifies the AC power induced in the secondary coil L2. The DC / DC converter 35 converts the DC voltage from the rectifier circuit 31 into a value appropriate for the operation of the mobile terminal 40. This DC voltage is used, for example, for charging a secondary battery (not shown) that is an operation power source of the mobile terminal 40.

  The secondary side control circuit 33 is configured by a microcomputer and operates by receiving a part of the power from the rectifier circuit 31. The memory 34 stores an ID code unique to the power receiving device 30.

  The rectifier circuit 31 is connected to both ends of the secondary coil L2. A resonance system switching circuit 41 is connected between one end of the secondary coil L2 and the rectifier circuit 31. When receiving the ID request signal or the information signal from the primary side communication coil L3 using electromagnetic induction, the secondary side communication coil L4 outputs the received signal to the secondary side communication circuit 32. The secondary communication circuit 32 demodulates the ID request signal or the information signal and outputs the demodulated signal to the secondary control circuit 33.

  When the secondary control circuit 33 recognizes the ID request signal, the secondary control circuit 33 generates an ID signal including an ID code stored in the memory 34 and outputs the generated signal to the secondary communication circuit 32. The secondary side communication circuit 32 modulates the ID signal, and wirelessly transmits the modulated signal via the secondary side communication coil L4.

  When the secondary control circuit 33 recognizes the information signal, the secondary control circuit 33 switches the state of the resonance system switching circuit 41 through the switch drive circuit 38 based on the presence detection level included in the signal. Hereinafter, the resonance system switching circuit 41 will be described in detail.

  As shown in FIG. 3, the resonance system switching circuit 41 includes three capacitors C2a to C2c and first to third photo MOS (Metal Oxide Semiconductor) 42a to 42c. The capacitor C2a and the photoMOS 42a are connected in series, the capacitor C2b and the photoMOS 42b are connected in series, and the capacitor C2c and the photoMOS 42c are connected in series. Each capacitor and photoMOS connected in series are connected in parallel.

  The first to third photo MOSs 42a to 42c include a light emitting diode 43, a photovoltaic cell 44, and two FETs (Field-Effect Transistors) 45a and 45b. Each light emitting diode 43 is connected to the switch drive circuit 38. The photovoltaic cell 44 is connected to the gate terminals of both FETs 45a and 45b. The drain terminals and the source terminals of the FETs 45a and 45b are connected to a connection line between the secondary coil L2 and the rectifier circuit 31.

  The switch drive circuit 38 turns on the light emitting diode 43 based on the command signal from the secondary side control circuit 33. When receiving light from the light emitting diode 43, the photovoltaic cell 44 applies a constant voltage to the gate terminals of the FETs 45a and 45b. Thereby, between the drain terminal and source terminal of FET45a, 45b will be in a conduction state. This is the ON state of the first to third photoMOSs 42a to 42c.

  Here, as shown in FIGS. 5A to 5C, based on the presence detection level, the secondary coil L2 is any of the directly-facing position, the first position, and the second position with respect to the primary coil L1. Can be determined. Specifically, as shown in FIG. 5A, when the presence detection level is 0.9 or more, it can be determined that the secondary coil L2 is present at the directly facing position with respect to the primary coil L1. is there. Further, as shown in FIG. 5B, when the presence detection level is 0.7 or more and less than 0.9, it is determined that the secondary coil L2 is present at the first position with respect to the primary coil L1. Is possible. Further, as shown in FIG. 5C, when the presence detection level is less than 0.7, it can be determined that the secondary coil L2 is present at the second position with respect to the primary coil L1.

  Thus, the position of the secondary coil L2 can be determined through the presence detection level. Therefore, in this example, the unit control circuit 19, the primary coil L1, and the voltage detection circuit 17 in the power feeding apparatus 10 that is a configuration for calculating the presence detection level correspond to the coil position determination unit.

As shown in the table of FIG. 4, the secondary side control circuit 33 switches the on / off states of the first to third photo MOSs 42a to 42c based on the presence detection level included in the information signal. Less than,
The reason why the states of the photoMOSs 42a to 42c are switched according to the presence detection level, that is, the position of the secondary coil L2 with respect to the primary coil L1 will be described.

  FIG. 6 shows a resonance system indicating the output power of the power receiving device 30 according to the operating frequency of the primary coil L1. As shown in the figure, there are two resonance frequencies, a primary resonance frequency fa and a secondary resonance frequency fb. These resonance frequencies fa and fb are resonance frequencies when the secondary coil L2 is in a position facing the primary coil L1.

  Here, when the operating frequency f1 is set in the vicinity of the primary resonance frequency fa, the impedance in the state where both the coils L1 and L2 are magnetically coupled is excessively reduced, thereby reducing the circuit efficiency. Therefore, in this example, the operating frequency f1 supplied to the primary coil L1 is set in the vicinity of the secondary resonance frequency fb in order to use the secondary resonance frequency fb. The resonance frequency is derived from the following equation.

式（１）より、漏れインダクタンスＬｅ又はコンデンサの容量Ｃが大きいほど共振周波数が小さくなることがわかる。２次コイルＬ２が１次コイルＬ１に正対した位置から給電板６の面方向にずらされた場合には、漏れインダクタンスＬｅが増大していく。従来の構成においては、これに伴って、図６に示される共振系は、共振周波数が小さくなる方向（図中の左方向）に移動する。図６の実線で示す正対位置における共振系から、左側に一定値Ａ１だけずれた位置に図６の一点鎖線で示す第１の位置における共振系が存在する。そして、正対位置における共振系から、左側に上記一定値Ａ１より大きい一定値Ａ２だけずれた位置に図６の二点鎖線で示す第２の位置における共振系が存在する。

From the equation (1), it can be seen that the resonance frequency decreases as the leakage inductance Le or the capacitance C of the capacitor increases. When the secondary coil L2 is shifted from the position facing the primary coil L1 in the surface direction of the power feeding plate 6, the leakage inductance Le increases. In the conventional configuration, accordingly, the resonance system shown in FIG. 6 moves in a direction in which the resonance frequency decreases (left direction in the figure). The resonance system in the first position indicated by the alternate long and short dash line in FIG. 6 exists at a position shifted by a certain value A1 on the left side from the resonance system in the directly facing position indicated by the solid line in FIG. Then, the resonance system at the second position indicated by the two-dot chain line in FIG. 6 exists at a position shifted from the resonance system at the directly-facing position by a certain value A2 larger than the certain value A1 on the left side.

  The secondary side control circuit 33 suppresses the shift of the resonance system with respect to the operating frequency f1 through the on / off switching of the first to third photo MOSs 42a to 42c. That is, the secondary side control circuit 33 turns on the first to third photoMOSs 42a to 42c, assuming that the secondary coil L2 is at the directly facing position when the presence detection level is 0.9 or more. At this time, since the three capacitors C2a to C2c are effective, the capacitance C of the above equation (1) is maximized. In this case, the output system W1 can be obtained by exciting the primary coil L1 at the operating frequency f1 in the resonance system at the directly-facing position indicated by the solid line in FIG.

  Further, when the presence detection level is 0.7 or more and less than 0.9, the secondary side control circuit 33 turns on the first and second photo MOSs 42a and 42b, assuming that the secondary coil L2 is in the first position. The third photoMOS 42c is turned off. At this time, since the two capacitors C2a and C2b are effective, the capacitance C of the above formula (1) is smaller than that in the case of the directly facing position. As a result, the resonance system moves to the right by a constant value A1 in FIG. This constant value A1 is the same value as the shift amount to the left side of the resonance system with the increase in the leakage inductance Le when the secondary coil L2 shifts from the directly-facing position to the first position. In other words, the capacitance of the capacitor C2c is set so as to be the same value. Therefore, the shift of the resonance system due to the increase in the leakage inductance Le is offset by the decrease in the capacitance C. As a result, the position of the resonance system does not change even when the secondary coil L2 is in the first position. For this reason, the output power W1 can be obtained even in the first position.

  Further, when the presence detection level is less than 0.7, the secondary side control circuit 33 assumes that the secondary coil L2 is in the second position, turns on the first photoMOS 42a, and sets the second and third The photo MOSs 42b and 42c are turned off. At this time, since only the capacitor C2a is effective, the capacitance C of the above formula (1) is further smaller than that in the first position. As a result, the resonance system moves to the right side by a constant value A2 in FIG. This constant value A2 is the same value as the shift amount to the left side of the resonance system accompanying the increase in the leakage inductance Le when the secondary coil L2 shifts from the directly opposed position to the second position. In other words, the capacitances of the capacitors C2b and C2c are set so as to have the same value. Therefore, the shift of the resonance system due to the increase in the leakage inductance Le is offset by the decrease in the capacitance C. As a result, the position of the resonance system does not change even when the secondary coil L2 is in the second position. For this reason, the output power W1 can be obtained also in the second position. Therefore, a more stable output of the power receiving device 30 can be obtained regardless of the position of the secondary coil L2.

As described above, according to the embodiment described above, the following effects can be obtained.
(1) The position of the resonance system with respect to the operating frequency f1 is changed by changing the capacitance C of the above equation (1) through switching of the effective capacitors C2a to C2c according to the position of the secondary coil L2 with respect to the primary coil L1. Is kept constant. Therefore, a more stable output of the power receiving device 30 can be obtained regardless of the position of the secondary coil L2.

  (2) The position of the resonance system with respect to the operating frequency f1 is set by changing the capacitance C. Accordingly, for example, even when the operating frequency f1 is determined in advance by a standard or the like, it is possible to obtain a more stable output of the power receiving device 30 while fixing the operating frequency f1 to a value in accordance with the standard.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. The contactless power feeding system of this embodiment is configured in the same manner as in the first embodiment except that the position determination method of the secondary coil L2 with respect to the primary coil L1 is different from that in the first embodiment. The Hereinafter, a description will be given focusing on differences from the first embodiment.

  As shown in FIG. 7, the power supply unit 15 includes a presence detection circuit 50. The presence detection circuit 50 includes LEDs (light emitting diodes) 51a to 51l and light receiving elements 52a to 52l.

  As shown in FIG. 8, the LEDs 51a to 51l and the light receiving elements 52a to 52l are arranged on a substrate 55 having a square plate shape. The substrate 55 is made of a material having a high magnetic permeability to such an extent that the magnetic flux from the primary coil L1 is not hindered. As shown in FIG. 9, this board | substrate 55 is installed in the upper surface of each primary coil L1.

  Specifically, as shown in FIG. 8, the LEDs 51 a to 51 l are arranged so as to draw a square along the edge of the substrate 55. An LED 51a is provided at the upper left corner of the substrate 55 in the drawing, and an LED 51d is provided at the upper right corner. Further, an LED 51j is provided at the lower left corner of the substrate 55 in the drawing, and an LED 51g is provided at the lower right corner of the substrate 55 in the drawing. The LEDs 51b and 51c are provided from the left between the LEDs 51a and 51d, and the LEDs 51e and 51f are provided from the top between the LEDs 51d and 51g. Further, LEDs 51h and 51i are provided from the right between the LEDs 51g and 51j, and LEDs 51k and 51l are provided from the bottom between the LEDs 51j and 51a. Corresponding to the LEDs 51a to 51l, light receiving elements 52a to 52l are provided on the lower right thereof. The power feeding plate 6 is made of a highly translucent material. Further, the LEDs 51 a to 51 l and the light receiving elements 52 a to 52 l are provided at positions in contact with the lower surface of the power supply plate 6. Each LED 51a to 51l emits light to the outside of the power feeding plate 6, and when the power receiving device 30 is present on the power feeding plate 6, each light receiving element 52a to 52l receives the reflected light.

  The unit control circuit 19 determines the position of the secondary coil L2 with respect to the primary coil L1 through the presence detection circuit 50 at regular intervals. That is, the unit control circuit 19 turns on the LEDs 51a to 51l in order. At this time, if the power receiving device 30 exists in the light irradiation direction of the LEDs 51 a to 51 l, the light is reflected by the power receiving device 30. The light receiving elements 52 a to 52 l detect the presence or absence of the reflected light, and output the detection result to the unit control circuit 19.

  The unit control circuit 19 wirelessly transmits the detected number of light receiving elements 52a to 52l through the primary side communication circuit 18 and the primary side communication coil L3 with the information signal including the number detected. When receiving the information signal from the primary side communication coil L3 using electromagnetic induction, the secondary side communication coil L4 outputs the received signal to the secondary side communication circuit 32. The secondary communication circuit 32 demodulates the information signal and outputs the demodulated signal to the secondary control circuit 33.

  Here, it is possible to determine the position of the secondary coil L2 with respect to the primary coil L1 based on the number of detected light detectors 52a to 52l that there is reflected light. That is, it can be determined that the position of the secondary coil L2 with respect to the primary coil L1 is shifted as the number decreases. Therefore, the secondary side control circuit 33 is configured so that the secondary coil L2 is in a directly-facing position with respect to the primary coil L1, based on the number of light receiving elements 52a to 52l detected that there is reflected light included in the information signal. It is determined whether it is present at the position 1 or the second position. For example, the secondary control circuit 33 assumes that the secondary coil L2 is in the directly facing position when the number of detected light elements among the light receiving elements 52a to 52l being 11 or more is the same as in the first embodiment. The first to third photo MOSs 42a to 42c are turned on. Further, the secondary side control circuit 33 assumes that the secondary coil L2 is in the first position when the number of the light receiving elements 52a to 52l detected that there is reflected light is 8 or more and less than 11, the first and second The photo MOSs 42a and 42b are turned on, and the third photo MOS 42c is turned off. Further, when the number of detected light reflection elements among the light receiving elements 52a to 52l is less than 8, the secondary side control circuit 33 determines that the secondary coil L2 is in the second position and sets the first photoMOS 42a. The second and third photoMOSs 42b and 42c are turned off by turning on. Thereby, it is possible to obtain a more stable output of the power receiving device 30 regardless of the position of the secondary coil L2 as in the above embodiment.

In the present embodiment, the presence detection circuit 50 and the unit control circuit 19 correspond to a coil position determination unit.
As described above, according to the embodiment described above, the following effects can be achieved.

  (3) Light is emitted from the LEDs 51a to 51l to the power feeding plate 6 side. The position of the power receiving device 30 (secondary coil L2) with respect to the primary coil L1 can be determined based on the presence or absence of reflected light with respect to the light. Therefore, similarly to the first embodiment, the capacitance C can be changed according to the position of the secondary coil L2. Therefore, a stable output of the power receiving device 30 can be obtained regardless of the position of the secondary coil L2.

In addition, the said embodiment can be implemented with the following forms which changed this suitably.
In each of the above embodiments, the resonance system is shifted in a state where the operating frequency f1 is fixed by changing the capacitance C of the above equation (1). However, the operating frequency f1 may be changed. In this case, the resonance system switching circuit 41 is omitted, and a frequency switching circuit is provided in the excitation drive circuit 16, for example. Even in this case, stable output power can be obtained by setting the operating frequency f1 in the vicinity of the resonance frequency of the secondary coil according to the position of the secondary coil L2 with respect to the primary coil L1. In this configuration, since transmission / reception of information signals is not required, both communication circuits 18 and 32 can be omitted.

  In the above embodiments, the three capacitors C2a to C2c are connected in parallel to each other, but the number of capacitors is not limited to this. The number of photo MOSs is determined according to the number of capacitors. In addition, the configuration of the resonance system switching circuit 41 is not limited to the above embodiments as long as the capacitance C of the above formula (1) can be changed. For example, a variable capacitor that can change the capacitance C may be employed.

  The position of the secondary coil L2 relative to the primary coil L1 can be determined based on the presence detection level in the first embodiment and the detection results of the light receiving elements 52a to 52l in the second embodiment. However, the method is not limited to the above two embodiments as long as the position can be determined. For example, a capacitance sensor may be arranged along the power supply plate 6 and the position of the secondary coil L2 relative to the primary coil L1 may be determined based on the detection result of the sensor.

  -The number and installation position of LED51a-51l and light receiving element 52a-52l are not limited to 2nd Embodiment. For example, you may provide LED and a light receiving element also in the center of the board | substrate 55 in FIG.

  In the first embodiment, the unit control circuit 19 determines whether the position of the secondary coil L2 is the directly-facing position, the first position, or the second position based on the presence detection level, and the determination The result may be included in the information signal and transmitted wirelessly. This determination may be made by the secondary control circuit 33. Similarly, in the second embodiment, the unit control circuit 19 determines whether the position of the secondary coil L2 is the directly-facing position, the first position, or the second position based on the detection results of the light receiving elements 52a to 52l. And the result of the determination may be included in the information signal and transmitted wirelessly.

  In the above embodiments, the effective capacitors C2a to C2c are switched using the photo MOSs 42a to 42c. However, as long as it is a switching element that can switch the effective capacitors C2a to C2c, it may be a FET other than a photo MOS, or may be a mechanical switch.

  In the first embodiment, the presence detection level is included in the information signal for transmission. However, the detection result of the voltage detection circuit 17 may be included in this information signal as it is. In this case, the secondary control circuit 33 calculates the presence detection level based on the detection result of the voltage detection circuit 17 included in the information signal, and on / off of the first to third photoMOSs 42a to 42c based on the presence detection level. The state may be switched.

  -In 2nd Embodiment, although LED51a-51l was employ | adopted as a light emitting element, as long as it light-emits, it may be a light bulb instead of LED. An infrared sensor may be used.

  The unit control circuit 19 in the above embodiment may be omitted. In this case, the common control circuit 12 also performs the control executed by the unit control circuit 19 in the above embodiment. Further, the common control circuit 12 may perform part of the control performed by the unit control circuit 19, or the unit control circuit 19 may perform part of the control performed by the common control circuit 12.

Next, the technical idea that can be grasped from the embodiment will be described together with the effects.
(A) The contactless power feeding system according to claim 2, wherein the switching element is a photo MOS.

  6 ... Power feeding plate, 10 ... Power feeding device, 11 ... Common unit, 12 ... Common control circuit, 13 ... Power supply circuit, 15 ... Power feeding unit, 16 ... Excitation drive circuit, 19 ... Unit control circuit, 30 ... Power receiving device, 40 ... Mobile terminal, 41 ... resonant switching circuit, 42a-42c ... photo MOS, 45a, 45b ... FET, 51a-51l ... LED, 52a-52l ... light receiving element, C1, C2a-C2c ... capacitor, L1 ... primary coil, L2 ... secondary coil, L3 ... primary side communication coil, L4 ... secondary side communication coil.

Claims (2)

In a state where a plurality of primary coils that generate an alternating magnetic flux by being supplied with an alternating current that vibrates at an operating frequency are arranged along the power supply surface, and the primary coil is installed on the power supply surface, A non-contact power feeding system using a resonance phenomenon in the secondary coil, comprising: a power receiving device having a secondary coil that generates an induced power based on the alternating magnetic flux from and supplies the power to a load;
A coil position determination unit for determining a position of the secondary coil with respect to the primary coil;
A switching circuit for switching a value of a resonance frequency in the secondary coil with respect to the operating frequency;
A control circuit that sets the resonance frequency to a value corresponding to the operating frequency through the switching circuit based on the determination result of the coil position determination unit;
The coil position determination unit
A light emitting element that is provided for each primary coil and that emits light to the power receiving device on the power feeding surface;
A light receiving element that is provided corresponding to the light emitting element and detects the presence or absence of reflected light when the light is emitted to the power receiving device on the power feeding surface;
A non-contact power feeding system comprising: a determination unit configured to determine a position of the secondary coil with respect to the primary coil based on the number of the light receiving elements detected to be reflected light among the light receiving elements. . In the non-contact electric power feeding system of Claim 1,
The switching circuit is connected in series to the secondary coil and includes a plurality of sets of capacitors and switching elements connected in series with each other, each set being connected in parallel, and through switching of the on / off states of the switching elements. A contactless power feeding system, wherein the value of the resonance frequency with respect to the operating frequency is switched.

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