PRIMARY-SIDE POWER CONTROL FOR INDUCTIVE POWER TRANSFER

• US 20150188320A1
• Filed: 12/29/2014
• Published: 07/02/2015
• 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, Thrimawithana, Duleepa Jayanath
• Granted Patent: US 9,461,480 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 is provided for controlling the output voltage of a pickup in an inductive power transfer (IPT) system without any additional form of communications for feedback from the pickup to the power supply. The method comprising the steps of deriving an estimate of the output voltage of the pickup from the voltage across the primary conductive path, and adjusting the current in the primary conductive path so that the estimated pickup output voltage matches a required pickup output voltage. In particular, an estimate of the pickup output voltage is derived from the magnitude and phase angle of the voltage in the primary conductive path.

Claims

1. A method of regulating output power on a secondary side of an inductive power transfer (IPT) system, the method comprising steps of:

measuring, using a controller of a primary side of the IPT system, the phase angle between voltage across and current in a conductive path of the primary side having unknown or variable mutual coupling with a pickup coil of the secondary side;

calculating, using the primary side controller, an imaginary component of the voltage across the primary conductive path using the measured phase angle;

determining, using the primary side controller, the unknown or variable mutual coupling using the calculated imaginary component; and

adjusting, under control of the primary side controller, current in the primary conductive path based on the determined mutual coupling to regulate the power output by the primary side thereby regulating the output power of the coupled secondary side.

2. The method according to claim 1, wherein the step of adjusting the current in the primary conductive path comprises controlling, using the primary side controller, a voltage supplied to the primary conductive path by a power supply.

3. The method according to claim 2, further comprising:

estimating, using the primary side controller, the output voltage of the secondary side based at least in part on the voltage across the primary conductive path and the determined mutual coupling,

wherein the voltage supplied to the primary conductive path is controlled so that the estimated output voltage matches a required output voltage of the secondary side.

4. The method according to claim 3, wherein the step of estimating the output voltage of the secondary side comprises calculating, using the primary side controller, a real component of the voltage across the primary conductive path using the measured phase angle.

5. An apparatus for regulating output power on a secondary side of an inductive power transfer (IPT) system, the apparatus comprising a conductive path of a primary side of the IPT system having unknown or variable mutual coupling with a pickup coil of the secondary side, a power supply for supplying power to the primary conductive path, and a controller for controlling the primary side, the controller configured to:

measure the phase angle between voltage across and current in the primary conductive path;

calculate an imaginary component of the voltage across the primary conductive path using the measured phase angle;

determine the unknown or variable mutual coupling using the calculated imaginary component; and

adjust current in the primary conductive path based on the determined mutual coupling to regulate the power output by the primary side thereby regulating the output power of the coupled secondary side.

6. The apparatus according to claim 5, wherein the controller is configured to adjust the current in the primary conductive path by controlling a voltage supplied to the primary conductive path by the power supply.

7. The apparatus according to claim 6, wherein the controller is configured to:

estimate the output voltage of the secondary side based at least in part on the voltage across the primary conductive path and the determined mutual coupling; and

control the voltage supplied to the primary conductive path so that the estimated output voltage matches a required output voltage of the secondary side.

8. The apparatus according to claim 7, wherein the controller is configured to estimate the output voltage of the secondary side by calculating a real component of the voltage across the primary conductive path using the measured phase angle.

9. The apparatus according to claim 6, wherein the power supply comprises an inverter connected to the primary conductive path, the controller being configured to control operation of the inverter to control the supplied voltage.

10. The apparatus according to claim 9, wherein:

the inverter comprises two pairs of switches in an H-bridge configuration; and

the controller is configured to operate each pair of switches using symmetric square wave driving signals so as to control the supplied voltage by phase shifting one driving signal with respect to another by an angle of between 180° and

360°

.

11. The apparatus according to claim 10, wherein the supplied voltage is controlled using pulse-width modulation.

12. The apparatus according to claim 10, wherein the supplied voltage is controlled using a pre-regulator.