BI-DIRECTIONAL INDUCTIVE POWER TRANSFER

• US 20110254379A1
• Filed: 11/26/2009
• Published: 10/20/2011
• Est. Priority Date: 11/26/2008
• Status: Active Grant

• Current Assignee: Auckland UniServices Limited (Auckland University)
• Original Assignee: Auckland UniServices Limited (Auckland University)
• Inventors: Madawala, Udaya Kumara
• Granted Patent: US 10,355,526 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 53/12 Inductive energy transfer
• CPC Class Codes: B60L 55/00 Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements
• 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 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02M 3/33584 Bidirectional converters
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles
• CPC Class Codes: Y04S 10/126 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]

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.

Claims

1. A control method for an inductive power transfer (IPT) system, the method comprising the step of controlling the relative phase angle of a pickup converter on a secondary side of the system with respect to a power supply converter on a primary side of the system to control the transfer of power between a primary conductive path and a load associated with the pickup.

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

3. The control method of claim 1 wherein the phase angle may be varied between 0°

and ±

90° and

is proportional to the magnitude of power transfer required to obtain a required pickup output.

4. The control method of claim 1 wherein the method further comprises the steps of controlling the relative phase angle to maintain a constant ±

90°

angle between the pickup and power supply converters, and controlling the magnitude of power transfer by varying the secondary converter output voltage to maintain a required pickup output.

5. The control method of claim 4 wherein the step of varying the secondary converter output voltage magnitude comprises varying the pulse width of the secondary converter output voltage.

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

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

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

9. A pickup for an inductive power transfer (IPT) system, the pickup comprising:

a phase detector for detecting the phase of a voltage in a primary conductive path with which the pickup is inductively coupled in use;

a converter allowing adjustable phase; and

a controller adapted to control the power transfer between the primary conductive path and a load associated with the pickup, by controlling at least the phase angle of the converter with respect to that of the primary conductive path voltage.

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

11. The pickup of claim 9 wherein the phase detector is adapted to detect the phase of the primary conductive path voltage by detecting the phase of a voltage induced in the pickup.

12. The pickup of claim 9 wherein the controller is adapted to vary the phase angle between 0°

and ±

90°

, proportional to the magnitude of power transfer required to obtain a required pickup output.

13. The pickup of claim 9 wherein the controller is adapted to maintain a constant ±

90°

phase angle between the pickup converter output and the primary conductive path voltage, and to control the magnitude of power transfer by varying the secondary converter output voltage to maintain a required pickup output.

14. The pickup of claim 9 wherein the controller is further adapted to control the direction of power flow by causing the pickup 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 side.

15. 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 electrically coupled to a load, the pickup being adapted to control the relative phase angle of the converter output with respect to that of the voltage in the primary conductive path to control the transfer of power between the primary conductive path and the load.

16. The IPT system of claim 15 wherein the power supply and the pickup each further comprise a tuned inductor-capacitor-inductor (LCL) circuit.

17. The IPT system of claim 15 wherein the IPT system comprises a single pickup and the power supply is adapted to supply the minimum alternating track current which is sufficient to supply the load.

18. The IPT system of claim 15 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 substantially constant alternating current to the primary conductive path.

19. The IPT system of claim 15 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 pickup converter output voltage and the output voltage of a primary converter of the power supply, wherein the power transferred to the load is proportional to the relative phase angle in the range of 0°

to ±

90°

.

20. The IPT system of claim 15 wherein the 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 primary converters is controlled to be substantially equal to ±

90°

.

21. The IPT system of claim 15 wherein the or each converter comprises a reversible inverter/rectifier, and the direction of power transfer is controlled by causing the pickup 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.

22. The IPT system of claim 15 wherein the or each pickup in the system is adapted to independently control 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.

23. The IPT system of claim 15 wherein the power supply also 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.

24-25. -25. (canceled)