Bi-directional inductive power transfer

Patent metadata

Field	Value
Publication number	US-10355526-B2
Application number	US-200913131155-A
Country	US
Kind code	B2
Filing date	Nov 26, 2009
Priority date	Nov 26, 2008
Publication date	Jul 16, 2019
Grant date	Jul 16, 2019

Abstract

A method, apparatus, and system are provided which enables the control of contactless power transfer in an inductive power transfer system using a phase control technique. The method comprises adjusting the phase of a secondary-side converter output voltage with respect to that of a primary-side converter. The magnitude of power transfer is determined by the relative phase angle, and the direction of power transfer is determined by whether the secondary converter output voltage leads or lags the input converter voltage, thereby enabling bi-directional power transfer between the primary and secondary sides of the system. According to alternative embodiments, the method may also be used for uni-directional power transfer only, and/or the secondary converter may be operated to maintain a constant relative phase angle.

First claim

The invention claimed is:

1. A control method for an inductive power transfer (IPT) system having a primary side comprising a primary converter and a primary resonant circuit, and a secondary side comprising a secondary converter and a secondary resonant circuit, the method comprising the steps of:
controlling a relative phase angle of the secondary converter with respect to the primary converter while maintaining the secondary resonant circuit tuning to be the same as the primary resonant circuit tuning to control a transfer of power between the primary side and the secondary side; and
controlling a magnitude of power transfer by varying a secondary converter output voltage to maintain a required pickup output, wherein varying the secondary converter output voltage magnitude comprises varying a pulse width of the secondary converter output voltage.

2. The control method of claim 1 wherein the primary and secondary resonant circuits each further comprise a tuned inductor-capacitor-inductor (LCL) circuit.

3. The control method of claim 1 wherein the relative phase angle may be varied between 0° and ±90° and is proportional to the magnitude of power transfer required to obtain the required pickup output.

4. The control method of claim 1 wherein the method further comprises the step of controlling the relative phase angle to maintain a constant ±90° angle between the secondary and primary converters.

5. The control method of claim 1 , wherein the method further comprises the step of controlling a voltage of the primary converter to maintain a constant current through a primary conductive path unless all loads are removed from the system.

6. The control method of claim 1 , wherein the method further comprises the step of controlling a voltage of the primary converter to maintain a the minimum current through a primary conductive path sufficient for a pickup controller to maintain the required pickup output.

7. The control method of claim 1 , wherein the method further comprises the step of controlling a direction of power flow by causing the secondary converter to either lag or lead the primary converter by a required phase angle, thereby enabling bi-directional power transfer between the secondary side and the primary side of the IPT system.

8. A pickup for an inductive power transfer (IPT) system, the pickup comprising:
a phase detector for detecting an indication of a phase of a voltage in a primary conductive path with which the pickup is inductively coupled in use;
a resonant circuit to receive power inductively from the primary conductive path;
a converter allowing adjustable phase; and
a controller adapted to control a power transfer between the primary conductive path and a load associated with the pickup, by controlling at least a phase angle of the converter with respect to that of the primary conductive path voltage while maintaining the resonant circuit tuning the same as a primary resonant circuit tuning and controlling a magnitude of power transfer by varying the converter output voltage to maintain a required pickup output, wherein varying the converter output voltage magnitude comprises varying a pulse width of the converter output voltage.

9. The pickup of claim 8 wherein the resonant circuit of the pickup comprises a tuned inductor-capacitor-inductor (LCL) circuit.

10. The pickup of claim 8 wherein the phase detector is adapted to detect the phase of the primary conductive path voltage by detecting a phase of a voltage induced in the pickup.

11. The pickup of claim 8 wherein the controller is adapted to vary the phase angle between 0° and ±90°, proportional to the magnitude of power transfer required to obtain the required pickup output.

12. The pickup of claim 8 wherein the controller is adapted to maintain a constant ±90° phase angle between a converter output and the primary conductive path voltage.

13. The pickup of claim 8 wherein the controller is further adapted to control a direction of power flow by causing the converter to either lag or lead the primary conductive path voltage by a required phase angle, thereby enabling bi-directional power transfer between the pickup and the primary conductive path.

14. An inductive power transfer (IPT) system comprising:
a power supply adapted to control the alternating current in a primary conductive path; and
at least one pickup inductively coupled with the primary conductive path in use and comprising a converter and a resonant circuit electrically coupled to a load, the pickup being adapted to control the relative phase angle of the converter output with respect to that of a the voltage in the primary conductive path while maintaining the resonant circuit tuning at the same as a primary resonant circuit tuning to control a transfer of power between the primary conductive path and the load and control a magnitude of power transfer by varying a converter output voltage to maintain a required pickup output, wherein varying the converter output voltage magnitude comprises varying a pulse width of the converter output voltage.

15. The IPT system of claim 14 wherein the resonant circuit comprises a tuned inductor-capacitor-inductor (LCL) circuit.

16. The IPT system of claim 14 wherein the IPT system comprises a single pickup and the power supply is adapted to supply a minimum alternating track current which is sufficient to supply the load.

17. The IPT system of claim 14 wherein the IPT system comprises a plurality of pickups inductively coupled with the primary conductive path, and the power supply is adapted to supply a constant alternating current to the primary conductive path.

18. The IPT system of claim 14 wherein the power supplied by the or each pickup to its respective load is controlled by the pickup and is determined by the relative phase angle between the converter output voltage and an output voltage of a primary converter of the power supply, wherein the magnitude of power transferred to the load is proportional to the relative phase angle in a range of 0° to ±90°.

19. The IPT system of claim 14 wherein a voltage supplied by the or each pickup to the respective load is controlled by the pickup and determined by the pulse width of the converter, wherein the relative phase angle between the pickup and a primary converter is controlled to be equal to ±90°.

20. The IPT system of claim 14 wherein the or each converter comprises a reversible inverter/rectifier, and a direction of power transfer is controlled by causing the converter output voltage to either lag or lead a primary converter output voltage by a required phase angle, thereby enabling bi-directional power transfer between the load and the primary conductive path.

21. The IPT system of claim 14 wherein the or each pickup in the system is adapted to independently control a the direction of power flow to/from the respective load, thereby allowing bi-directional power flow between the load and one or more other pickups via the primary conductive path.

22. The IPT system of claim 14 wherein the power supply further comprises a reversible inverter/rectifier, and power transferred from one or more pickups to the primary conductive path may be returned to a primary power source electrically coupled to the power supply, thereby allowing bi-directional power flow between one or more loads and the power source.

23. The control method of claim 1 wherein the relative phase angle comprises a phase angle between the secondary converter

Assignees

• Madawala Udaya Kumara
• Auckland Uniservices Ltd

Inventors

• Madawala Udaya Kumara

Classifications

• H02J7/933

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

• Y04S10/126

  the energy generation units being or involving electric vehicles [EV] or hybrid vehicles [HEV], i.e. power aggregation of EV or HEV, vehicle to grid arrangements [V2G] · CPC title

• Y02T10/7072

  Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors · CPC title

• Y02T90/16

  Information or communication technologies improving the operation of electric vehicles · CPC title

• B60L55/00

  Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements · CPC title