Coordinating voltage and frequency changes in wireless power transfer

Patent metadata

Field	Value
Publication number	US-2021384722-A1
Application number	US-202016894346-A
Country	US
Kind code	A1
Filing date	Jun 5, 2020
Priority date	Jun 5, 2020
Publication date	Dec 9, 2021
Grant date	—

Abstract

A wireless transmitter coordinates changes in the transmitter's input or output voltages with changes in the transmitter's operating frequency to counteract the transmitter's output power changes while changing the voltages. When the voltages are being increased, the output frequency is moved away from the resonant frequency. Consequently, the output power increase due to the increased voltages is restrained by the frequency change. Before or after the voltage increase, increased output power can be obtained by changing the output frequency while the input and output voltages are held constant or near constant. Some embodiments follow similar procedures when reducing the transmitter's input or output voltages. Calibration is performed before power transfer to determine suitable voltage and frequency profiles for voltage change operations. Other features are also provided.

First claim

What is claimed is:

1 . A wireless power transmitter for wireless power transfer (WPT), the transmitter comprising:
an input for receiving a WPT input signal; an output for connection to a transmit coil; a transmit circuit for converting the WPT input signal to a WPT output signal in the transmit coil; wherein the transmit circuit is configured to increase a voltage amplitude of the WPT output signal while moving the WPT signal frequency away from a resonant frequency of a resonant tank comprising the transmit coil.

2 . The wireless power transmitter of clause 1, wherein moving the WPT signal frequency away from the resonant frequency reduces or eliminates an increase of a magnetic field and/or magnetic field's power generated by the transmit coil from the WPT signal when the WPT signal voltage amplitude is increased.

3 . The wireless power transmitter of claim 1 , wherein increasing the transmit coil voltage amplitude while moving the WPT signal frequency is performed in response to a WPT receiver's command.

4 . The wireless power transmitter of claim 3 , wherein the transmit circuit is further configured, in response to the command, before or after increasing the transmit coil voltage amplitude, to move the WPT signal frequency closer to the resonant frequency to increase the WPT signal power.

5 . The wireless power transmitter of claim 4 , wherein the transmit coil voltage amplitude is held constant while the WPT signal frequency moves closer to the resonant frequency.

6 . The wireless power transmitter of claim 1 , wherein the transmit circuit is configured to generate the WPT signal from an input signal, and increasing the transmit coil voltage amplitude comprises increasing an input signal voltage.

7 . The wireless power transmitter of claim 6 , wherein the input signal is a DC signal.

8 . The wireless power transmitter of claim 1 , wherein the transmit circuit comprises a memory, and is configured to engage in a calibration process with a wireless power receiver, the calibration process being performed when the wireless power receiver does not transfer power to a load, the calibration process comprising the transmitter transmitting wireless power to the receiver at a plurality of settings each of which defines the transmit coil voltage amplitude, the frequency, and one or more transitions of the transmit coil voltage amplitude and/or frequency, and the transmitter receiving, from the receiver, information on how each said setting affects a receiver voltage obtained in the receiver, and storing the settings and the corresponding information in the memory;
wherein during the WPT, when the receiver transfers power to the load, the transmitter receives the receiver's commands specifying desired values for the receiver voltage, and the transmitter executes the commands based on the information stored in the memory for the settings.

9 . The wireless power transmitter of claim 8 , wherein at least one setting defines, for at least one transition, a length of a time interval to follow the transition without changing the WPT signal voltage amplitude.

10 . The wireless power transmitter of claim 8 , wherein in the calibration process, the transmitter receives from the receiver, for at least one setting, an indication that the setting caused an excessively high voltage condition in the receiver and is not to be used in the WPT.

11 . A method for wireless power transfer (WPT), the method comprising:
receiving, by a wireless power transmitter, an indication to increase a transmit coil voltage amplitude of a WPT signal transmitted by a transmit coil; in response to the indication, increasing the transmit coil voltage amplitude, and moving the WPT signal frequency away from a resonant frequency of a resonant circuit comprising the transmit coil, to reduce or eliminate the WPT signal's power increase associated with increasing the transmit coil voltage amplitude.

12 . The method of claim 11 , further comprising, in response to the indication, before or after increasing the transmit coil voltage amplitude, moving the WPT signal frequency closer to the resonant frequency to increase the WPT signal power.

13 . The method of claim 11 , wherein the transmit coil voltage amplitude is held constant while the WPT signal frequency moves closer to the resonant frequency.

14 . The method of claim 11 , wherein the transmitter generates the WPT signal from an input signal, and increasing the transmit coil voltage amplitude comprises increasing an input signal voltage.

15 . The method of claim 14 , wherein the input signal is a DC signal.

16 . The method of claim 11 , wherein the transmit circuit comprises a memory, and is configured to engage in a calibration process with a wireless power receiver, the calibration process being performed when the wireless power receiver does not transfer power to a load, the calibration process comprising the transmitter transmitting wireless power to the receiver at a plurality of settings each of which defines the transmit coil voltage amplitude, the frequency, and one or more transitions of the transmit coil voltage amplitude and/or frequency, and the transmitter receiving, from the receiver, information on how each said setting affects a receiver voltage obtained in the receiver, and storing the settings and the corresponding information in the memory;
wherein during the WPT, when the receiver transfers power to the load, the transmitter receives the receiver's commands specifying desired values for the receiver voltage, and the transmitter executes the commands based on the information stored in the memory for the settings.

17 . The wireless power transmitter of claim 16 , wherein at least one setting defines, for at least one transition, a length of a time interval to follow the transition without changing the WPT signal voltage amplitude.

18 . A wireless power receiver comprising:
an input for connection to a transmit coil; an output for connection to a load; and a receive circuit for converting a WPT input signal in the receive coil to provide power to the load; wherein the receive circuit comprises a memory, and is configured to engage in a calibration process with a wireless power transmitter, the calibration process being performed when the wireless power receiver does not transfer power to the load, the calibration process comprising the receiving wireless power in the receive coil from a wireless power transmitter at a plurality of settings each of which defines a transmit coil voltage amplitude, a WPT input signal frequency, and one or more transitions of a transmit coil voltage amplitude and/or frequency, and the receiver sending, to the transmitter, information on how each said setting affects a receiver voltage obtained in the receiver, and storing the settings and the corresponding information in the memory; wherein during the WPT, when the receiver transfers power to the load, the receiver sends to the transmitter commands specifying desired values for the receiver voltage.

19 . The wireless power receiver of claim 18 , wherein at least one setting defines, for at least one transition, a length of a time interval to follow the transition without changing the WPT signal voltage amplitude.

20 . The wireless power receiver of claim 18 , wherein in the calibration process, the receiver determines and sends to the transmitter information on whether at least one setting resulted in an excessively high voltage in the receiver.

Assignees

• Renesas Electronics America Inc

Inventors

• Mehas Gustavo
• Smith Nicholaus
• Qi Tao
• Huang Jiangjian

Classifications

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/94

  in response to battery current · CPC title

• H02J7/933

  the cycle being controlled or terminated in response to electric parameters · CPC title

• H02J7/44

  between battery management systems and power sources · CPC title

• H02J50/005 Primary

  Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices · CPC title