ELECTRIC POWER RECEIVING DEVICE AND NON-CONTACT POWER SUPPLY SYSTEM

• US 20150008755A1
• Filed: 06/26/2014
• Published: 01/08/2015
• Est. Priority Date: 07/02/2013
• Status: Abandoned Application

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Electronics Corporation
• Inventors: SONE, Yasuhiko
• Application Number:
  US14/315,886
• Publication Number:
  US 20150008755A1
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H02J 7/00045 Authentication, i.e. circuits for checking compatibility between one component, e.g. a battery or a battery charger, and another component, e.g. a power source
• CPC Class Codes: H02J 7/00308 Overvoltage protection

Abstract

In a non-contact power supply system, an electric power receiving device with suppressed heat generation is provided. The electric power receiving device is configured with a resonance circuit which includes a resonance capacity and a resonance coil acting as a receiving antenna, and receives electric power in a non-contact manner using resonant coupling of the resonance circuit. When receiving electric power, the electric power receiving device monitors the reception electric power received by the resonance circuit and controls the resonance frequency of the resonance circuit so as to keep the reception electric power from exceeding a target electric power level (PTGT). Accordingly, even when an electric power larger than the electric power required by the electric power receiving device is transmitted from the transmitting side, the electric power receiving device operates not to receive the electric power greater than the target electric power level.

Claims

1. An electric power receiving device comprising:

a resonance circuit including a resonance capacitor and a resonance coil acting as a receiving antenna, the electric power receiving device being operable to receive electric power in a non-contact manner with the use of resonant coupling of the resonance circuit,

wherein, in receiving the electric power, the reception electric power received by the resonance circuit is monitored, and a resonance frequency of the resonance circuit is controlled to keep the reception electric power from exceeding a target electric power level.

2. The electric power receiving device according to claim 1,

wherein when the reception electric power is not exceeding the target electric power level, the impedance of the resonance circuit is adjusted so as to match the resonance frequency of the resonance circuit with an electric power transmission frequency, and

wherein when the reception electric power is exceeding the target electric power level, the impedance of the resonance circuit is adjusted so as to shift the resonance frequency away from the electric power transmission frequency.

3. The electric power receiving device according to claim 2, further comprising:

a rectifier circuit operable to rectify an AC voltage corresponding to the electric power received by the resonance circuit to obtain a DC output voltage; and

an adjustment unit operable to monitor the output voltage of the rectifier circuit and to adjust impedance of the resonance circuit to keep the output voltage from exceeding a target voltage.

4. The electric power receiving device according to claim 3,

wherein the capacitance value of the resonance circuit is changed by the adjustment unit.

5. The electric power receiving device according to claim 4,

wherein the adjustment unit comprises:

a differential amplifier circuit operable to generate a control voltage so as to reduce a difference of the target voltage and the output voltage,

wherein the resonance circuit comprises;

a parallel resonance unit configured with the resonance coil and the resonance capacitor coupled in parallel; and

a first capacitor and a first variable resistance circuit coupled in series between one end of the parallel resonance unit and a reference node supplied with a fixed voltage, and

wherein the first variable resistance circuit changes a value of resistance on the basis of the control voltage.

6. The electric power receiving device according to claim 5,

wherein the resonance circuit further comprises:

a second capacitor and a second variable resistance circuit coupled in series between the other end of the parallel resonance unit and the reference node, and

wherein the second variable resistance circuit changes a value of resistance on the basis of the control voltage.

7. The electric power receiving device according to claim 6,

wherein the first variable resistance circuit and the second variable resistance circuit respectively include a transistor driven by the control voltage.

8. The electric power receiving device according to claim 4,

wherein the adjustment unit comprises:

a comparator circuit operable to compare a threshold voltage corresponding to the target voltage with the output voltage, to output the comparison result, and

wherein the resonance circuit comprises;

a parallel resonance unit configured with the resonance coil and the resonance capacitor coupled in parallel; and

a first capacitor and a first switching element coupled in series between one end of the parallel resonance unit and a reference node supplied with a fixed voltage, and

wherein the first switching element is on-off controlled, on the basis of the comparison result.

9. The electric power receiving device according to claim 8,

wherein the resonance circuit further comprises:

a second capacitor and a second switching element coupled in series between the other end of the parallel resonance unit and the reference node, and

wherein the second switching element is on-off controlled on the basis of the comparison result.

10. The electric power receiving device according to claim 9,

wherein the constants of the receiving coil and the resonance capacitor of the parallel resonance unit are set up so as to match the resonance frequency of the parallel resonance unit with the electric power transmission frequency, when the first switching element and the second switching element are set to OFF, and

wherein the adjustment unit sets the first switching element and the second switching element to ON when the output voltage is exceeding the target voltage and sets the first switching element and the second switching element to OFF when the output voltage is not exceeding the target voltage.

11. The electric power receiving device according to claim 4,

wherein the adjustment unit comprises:

a plurality of comparator circuits, each operable to compare a threshold voltage corresponding to the target voltage with the output voltage and to output the comparison result,

wherein the resonance circuit comprises;

a parallel resonance unit configured with the resonance coil and the resonance capacitor coupled in parallel; and

a plurality of impedance adjustment circuits, each including a first capacitor and a first switching element coupled in series between one end of the parallel resonance unit and a reference node supplied with a fixed voltage,

wherein each of the comparator circuits has a mutually different threshold voltage,

wherein the impedance adjustment circuits are provided corresponding to the comparator circuits, and

wherein the first switching element of each of the impedance adjustment circuits is on-off controlled, on the basis of the comparison result of the corresponding comparator circuit.

12. The electric power receiving device according to claim 10,

wherein the first switching element and the second switching element are mechanical switches which are controlled on the basis of the control voltage.

13. The electric power receiving device according to claim 3, further comprising:

a load circuit; and

a voltage control unit operable to receive the output voltage of the rectifier circuit and to supply it to the load circuit coupled in the latter stage,

wherein the voltage control unit adjusts the target voltage so as to match the voltage to be supplied to the load circuit with a desired voltage.

14. The electric power receiving device according to claim 4,

wherein the resonance circuit comprises a PIN diode to which a variable bias voltage is applied by the adjustment unit.

15. The electric power receiving device according to claim 3,

wherein the resonance circuit changes the inductance of the receiving coil.

16. The electric power receiving device according to claim 3, further comprising:

a rectifier circuit operable to rectify an AC voltage corresponding to the electric power received by the resonance circuit and to output a DC output voltage;

an input voltage detection unit operable to detect the input voltage supplied to the rectifier circuit by the resonance circuit; and

an adjustment unit operable to adjust the impedance of the resonance circuit to keep the input voltage detected by the input voltage detection unit from exceeding a target voltage.

17. The electric power receiving device according to claim 16,

wherein the rectifier circuit is a full wave rectifier circuit,

wherein the input voltage detection unit comprises:

a first peak hold circuit operable to detect a peak value of a positive side input voltage of the rectifier circuit;

a second peak hold circuit operable to detect a peak value of a negative side input voltage of the rectifier circuit; and

an averaging circuit operable to output an average value of the peak value detected by the first peak hold circuit and the peak value detected by the second peak hold circuit, and

wherein the adjustment unit adjusts the impedance of the resonance circuit to keep the average value of the averaging circuit from exceeding the target voltage.

18. A non-contact power supply system comprising:

an electric power transmitting device operable to transmit electric power in a non-contact manner with the use of the electromagnetic resonant coupling utilizing the resonance circuit; and

the electric power receiving device according to claim 2, operable to receive the electric power transmitted by the electric power transmitting device in a non-contact manner.

19. An electric power receiving device comprising:

a resonance circuit including a resonance capacitor and a resonance coil acting as a receiving antenna, the electric power receiving device being operable to receive the electric power in a non-contact manner with the use of resonant coupling of the resonance circuit,

wherein when receiving the electric power, the impedance of the resonance circuit is dynamically controlled to match the reception electric power received by the resonance circuit with a target electric power level.