Capacitive wireless power transfer by means of adaptive matching networks

Patent metadata

Field	Value
Publication number	US-10965156-B2
Application number	US-201816651225-A
Country	US
Kind code	B2
Filing date	Nov 6, 2018
Priority date	Nov 7, 2017
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

A controlled wireless Capacitive Power Transfer (CPT) system includes a primary side for wirelessly transmitting power to a secondary side via coupling plates having mutual capacitance C M . A primary adaptive matching network regulates the current flowing to the secondary side. A primary controller includes a first control loop for adjusting the switching frequency f sw to compensate for changes in the impedance of the primary matching network. A second control loop adjusts the resonant frequency of the primary resonant circuit to track the switching frequency f sw . A secondary adaptive matching network is comprised of a secondary resonant circuit with a bias-controlled variable secondary inductor serially connected to the mutual capacitance C M and a capacitor parallelly connected to the mutual capacitance C M , for matching the impedance of the secondary matching network. A secondary controller adjusts the impedance of the secondary matching network to match the resonant frequency of the primary resonant circuit.

First claim

The invention claimed is:

1. A controlled wireless Capacitive Power Transfer (CPT) system, based on adaptive matching networks, comprising:
a) a primary power transmitter side for wirelessly transmitting power to a secondary power receiver side via coupling plates having mutual capacitance C M ,
said primary power transmitter side comprising:
a.1) a power source connected to a power driver operating at a determined switching frequency f sw ;
a.2) a primary adaptive matching network comprised of a primary resonant circuit with a bias-controlled variable primary inductor serially connected to said mutual capacitance C M and a capacitor parallelly connected to said mutual capacitance C M , for regulating a current flowing to said secondary power receiver side via said mutual capacitance C M ; and
a.3) a primary controller comprised of:
a.3.1) a first control loop, for adjusting the switching frequency f sw to compensate for changes in impedance of said primary adaptive matching network, whenever said mutual capacitance C M changes;
a.3.1) a second control loop, for adjusting a resonant frequency of said primary resonant circuit to track the switching frequency f sw by providing appropriate bias to said bias-controlled variable primary inductor and changing the resonant frequency of said primary resonant circuit; and

said secondary power receiver side comprising:
b.1) a rectifier circuit connected to a load and operating at a resonant frequency of said primary resonant circuit;
b.2) a secondary adaptive matching network connecting between said mutual capacitance C M and said rectifier circuit and comprising a secondary resonant circuit with a bias-controlled variable secondary inductor serially connected to said mutual capacitance C M and a capacitor parallelly connected to said mutual capacitance C M for matching an impedance of said secondary adaptive matching network;
b.3) a secondary controller comprised of:
b.3.1) a control loop, for adjusting the impedance of said secondary adaptive matching network to match the resonant frequency of said primary resonant circuit by providing appropriate bias to said bias-controlled variable secondary inductor.

2. A system according to claim 1 , in which the first control loop is implemented by a digital phase-locked loop (DPLL).

3. A system according to claim 1 , in which the switching frequency is synthesized to continuously follow the resonant frequency of the primary power transmitter side, in response variations of system parameters.

4. A system according to claim 1 , in which power delivery from the primary power transmitter side to the secondary power receiver side is disengaged from cross-coupling interactions between said primary power transmitter and secondary power receiver sides and variations of electrical circuits and capacitive medium.

5. A system according to claim 1 , in which power delivery from the primary power transmitter side to the secondary power receiver side is adaptively tuned to satisfy required power conditions at either terminals of the coupling plates or at output terminals.

6. A system according to claim 1 , in which power delivery from the primary power transmitter side to the secondary power receiver side is adaptively tuned by adjusting the switching frequency and varying a value of one or more reactive components.

7. A system according to claim 1 , in which the primary and/or secondary adaptive matching network includes a bias controlled or a command controlled variable inductance or capacitance, wherein said variable inductance or capacitance is varied continuously or in segments.

8. A system according to claim 1 , in which the primary power transmitter side delivers constant current to the secondary power receiver side.

9. A system according to claim 1 , in which the resonant frequency of the primary and secondary resonant circuits is adjusted by changing the values of the respective bias-controlled variable primary and secondary inductors or parallel capacitors or both.

10. A system according to claim 1 , in which the switching frequency tracks the resonant frequency on the fly, and a transmitted power is regulated by characteristics of the primary resonant circuit.

11. A system according to claim 1 , in which the primary and/or secondary resonant circuit comprises a plurality of inductors and capacitors in either series connection, parallel connection, or a combination of both series and parallel connections.

12. A system according to claim 1 , in which the resonant circuit in each side comprises two or more variable components.

13. A system according to claim 1 , in which the bandwidth of the first control loop is the highest bandwidth, to obtain the fastest response, wherein the bandwidth of the control loop of the secondary power receiver side is lower than the bandwidth of the first control loop, and the bandwidth of the second control loop is the lowest bandwidth.

14. A system according to claim 1 , in which a bias driver of the bias-controlled variable primary and secondary inductors is realized by either a linear regulator or by a buck converter.

15. A system according to claim 14 , in which a current of the bias driver is regulated by an internal closed-current-loop.

16. A system according to claim 1 , in which the control loops are characterized by their bandwidth difference.

17. A system according to claim 1 , in which a transmitted signal at output terminals of the primary power transmitter side is modulated, for transmitting power to a plurality of loads, each corresponding to the secondary power receiver side, such that each load will receive a transmitted power at a different frequency.

18. A system according to claim 1 , in which a fourth feedback loop is employed to facilitate direct regulation of output characteristics through back communication from the secondary power receiver side to the primary power transmitter side, wherein said fourth feedback loop adjusts a signal transmitted from the primary power transmitter side until a desired transmitted signal is obtained.

19. A system according to claim 18 , in which the secondary power receiver side comprises an independent tuning circuit.

20. A method for controlling power transfer in a Capacitive Power Transfer (CPT) system as defined in claim 1 , comprised of the primary power transmitter side for wirelessly transmitting power to the secondary power receiver side via coupling plates having mutual capacitance C M and respective primary and secondary adaptive matching networks, the method comprising:
a) upon initiating a tuning of the primary and secondary adaptive matching networks, determining the switching frequency f sw , and the bias-controlled variable primary and secondary inductors according to a default set of pre-loaded values;
b) tuning the switching frequency f sw of the power driver of the first control loop;
c) detecting a phase difference between input signals V P and V CP and maintaining a 90° phase angle between V P and V CP at all times;
d) whenever the detected phase difference between said V P and V CP signals is not 90°, generating an error signal to create a new switching frequency f sw , until said switching frequency f sw equals the resonant frequency of said primary resonant circuit;
e) detecting a phase difference between input signals V S and V CS and maintaining said phase difference at 90°;
f) adjusting the secondary power receiver side's inductance value L S to tune the secondary adaptive matching network, accordin

Assignees

• B G Negev Technologies And Applications Ltd At Ben Gurion Univ

Inventors

• Peretz Mor Mordechai

Classifications

• H02M3/015

  with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit · CPC title

• H02M3/33573

  Full-bridge at primary side of an isolation transformer · CPC title

• H02J50/90

  involving detection or optimisation of position, e.g. alignment · CPC title

• H02J50/05 Primary

  using capacitive coupling · CPC title

• H02M3/33569

  having several active switching elements (H02M3/3353 takes precedence) · CPC title