FLEXIBLE BRIDGE AMPLIFIER FOR WIRELESS POWER

• US 20180301934A1
• Filed: 04/18/2017
• Published: 10/18/2018
• Est. Priority Date: 04/18/2017
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Prabhala, Venkata Anand, Schaecher, Stephan
• Granted Patent: US 11,038,374 B2
• Time in Patent Office: Days
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• 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 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007192 in response to temperature
• CPC Class Codes: H02M 1/0019 the disturbance parameters being load current fluctuations
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current

Abstract

A wireless power transfer (WPT) system that efficiently transfers power to portable devices over a wide range of load conditions and power output demands. The WPT system of this disclosure includes a full bridge topology. Changing the number of devices or the position and orientation of a device on the transmitter charge area may change the impedance and/or the load on the power transmitting unit (PTU). The WPT system of this disclosure may detect load impedance and/or power requested from the PTU. When the load exceeds a threshold, the WPT system will activate a second half bridge to operate in full-bridge mode. Similarly, the WPT system may detect the power requested and received and when the power drops to a certain threshold of power transmitted the WPT may turn off the second leg and operate in half-bridge mode.

Claims

1. A method comprising:

determining, by a sense and control unit, an output impedance of a power transfer circuit;

determining, by a sense and control unit, an output power of the power transfer circuit;

in response to determining that the output impedance is greater than an output impedance threshold or that the output power is greater than an output power threshold, selecting, by the sense and control unit, a full-bridge mode of operation of the power transfer circuit; and

in response to determining that the output impedance is less than the output impedance threshold or that the output power is less than the output power threshold, selecting, by the sense and control unit, a half-bridge mode of operation of the power transfer circuit.

2. The method of claim 1, wherein the power transfer circuit comprises a first half-bridge circuit and a second half-bridge circuit, the method further comprising selecting the half-bridge mode of operation comprises disabling the first half-bridge of the power transfer circuit.

3. The method of claim 2, wherein the first half bridge circuit comprises a high side switch and a low side switch and disabling the first half-bridge circuit comprises turning off the high side switch of first half-bridge circuit and turning on the low side switch of the first half-bridge circuit.

4. The method of claim 1, further comprising, executing, by the sense and control unit, a continuous mode transition, wherein the sense and control unit executes the continuous mode transition:

from an ending time of the half-bridge mode of operation to a starting time of the full-bridge mode of operation; and

from an ending time of the full-bridge mode of operation to a starting time of the half-bridge mode of operation.

5. The method of claim 1, further comprising:

determining by the sense and control unit, a DC input voltage of the power transfer circuit;

in response to determining that the DC input voltage greater than a DC input voltage threshold, selecting, by the sense and control circuit, a full-bridge mode of operation of the power transfer circuit; and

in response to determining that the DC input voltage is less than a DC input voltage threshold, selecting, by the sense and control unit, a half-bridge mode of operation of the power transfer circuit.

6. The method of claim 5, wherein the power transfer circuit includes a maximum DC input voltage and the DC input voltage threshold is half of the maximum DC input voltage.

7. The method of claim 1, wherein the power transfer circuit includes a maximum rated power output and the output power threshold is half of the maximum rated power output.

8. The method of claim 1, wherein the power transfer circuit includes a maximum reflected impedance and the output impedance threshold is half of the maximum reflected impedance.

9. The method of claim 1, wherein the sense and control unit adjusts the output power threshold and the sense and control unit adjusts the output impedance threshold based in part on operating conditions of the power transfer circuit, wherein the operating conditions comprise:

ambient temperature, resonator current and power supply voltage.

10. The method of claim 1, further comprising:

determining, by the sense and control unit, an output voltage of a power receiving unit (PRU);

determining, by the sense and control unit, a power level received by the PRU,

in response to determining that the output voltage is less than an output voltage setpoint or that the power level is less than a power level setpoint, increasing, by the sense and control unit, a direct current (DC) input voltage;

in response to determining that the output voltage is greater than the output voltage setpoint or that the power level is greater than the power level setpoint, decreasing, by the sense and control unit, the DC input voltage;

in response to determining that the output voltage equals the output voltage setpoint or the power level is equal to the power level setpoint, further determining, by the sense and control unit, whether the DC input voltage is less than a DC input voltage threshold;

in response to determining that the DC input voltage is less than the DC input voltage threshold, selecting, by the sense a control unit, the half-bridge mode of operation; and

in response to determining that the DC input voltage is greater than the input voltage threshold, selecting, by the sense a control unit, a full-bridge mode of operation.

11. A sense and control circuit, comprising:

a first sensing circuitry, wherein the first sensing circuitry is configured to determine an impedance reflected to a power amplifier circuit;

a second sensing circuitry, wherein the second sensing circuitry is configured to determine an output power of the power amplifier circuit; and

a third sensing circuitry, wherein the third sensing circuitry is configured to determine a DC input voltage of the power amplifier circuit;

wherein

in response to determining that;

the impedance reflected to the power amplifier circuit is greater than an impedance threshold,

the output power is greater than an output power threshold, or that

the DC input voltage is greater than a DC input voltage threshold, the sense and control circuity is configured to select a full-bridge mode of operation of the power amplifier circuit; and

in response to determining that;

the impedance reflected to the power amplifier circuit is less than the impedance threshold,

the output power is less than the output power threshold, or that

the DC input voltage is less than a DC input voltage threshold, the sense and control circuit is configured to select a half-bridge mode of operation of the power amplifier circuit.

12. The sense and control circuit of claim 11, wherein the sense and control circuit is configured to select the half-bridge mode of operation comprises disabling a first half-bridge of the power amplifier circuit.

13. The sense and control circuit of claim 12, wherein the sense and control circuit is configured to disable the first half-bridge circuit by turning off a first high side switch of the first half-bridge circuit and turning on a first low side switch of the first half-bridge circuit.

14. A device for wireless power transfer, the device comprising:

a power amplifier circuit that includes;

a first half-bridge circuit comprising a first high side switch and a first low side switch; and

a second half-bridge circuit comprising a second high side switch and a second low side switch, wherein

the first half-bridge circuit and the second half-bridge circuit are arranged as a full-bridge circuit; and

a sense and control circuit that is configured to;

determine an impedance reflected to the power amplifier circuit;

determine an output power of the power amplifier circuit;

in response to determining that the impedance reflected to the power amplifier circuit is greater than an impedance threshold or that the output power is greater than an output power threshold, select a full-bridge mode of operation of the power amplifier circuit; and

in response to determining that the impedance reflected to the power amplifier circuit is less than the impedance threshold or that the output power is less than the output power threshold, select a half-bridge mode of operation of the power amplifier circuit.

15. The device of claim 14, wherein the sense and control circuit is further configured to determine a DC input voltage of the power amplifier circuit;

in response to determining that the DC input voltage of the power amplifier circuit is greater than a DC input voltage threshold, select a full-bridge mode of operation of the power amplifier circuit; and

in response to determining that the DC input voltage of the power amplifier circuit is less than the DC input voltage threshold, select a half-bridge mode of operation of the power amplifier circuit.

16. The device of claim 15, wherein selecting the half-bridge mode of operation comprises disabling the first half-bridge circuit, including turning off the first high side switch of the first half-bridge circuit and turning on the first low side switch of the first half-bridge circuit.

17. The device of claim 14, wherein the sense and control circuit includes a continuous mode transition, and the sense and control circuit is further configured to execute the continuous mode transition:

from an ending time of the half-bridge mode of operation to a starting time of the full-bridge mode of operation; and

from an ending time of the full-bridge mode of operation to a starting time of the half-bridge mode of operation.

18. The device of claim 14, wherein the power amplifier circuit includes a maximum rated power output and the output power threshold is half of the maximum rated power output.

19. The device of claim 14, wherein the power transfer circuit includes a maximum reflected impedance and the impedance threshold is half of the maximum reflected impedance.

20. The device of claim 14, wherein the sense and control circuit adjusts the output power threshold and the sense and control circuit adjusts the impedance threshold based in part on operating conditions of the power transfer circuit, wherein the operating conditions comprise:

ambient temperature, resonator current and power supply voltage.