Thermal feedback for power transfer optimization

1. A wireless power-transfer system comprising:

a base power-transfer apparatus including a coil configured to generate a magnetic field based on an electric current;

a power supply unit including switching and power electronics configured to drive the electric current in the coil;

at least one temperature sensor configured to measure a temperature of the base power-transfer apparatus or the power supply unit; and

a system controller coupled to the base power-transfer apparatus, the power supply unit, and the at least one temperature sensor, the system controller configured to:

determine whether the measured temperature exceeds an upper temperature value of a defined temperature range; and

responsive to the measured temperature exceeding the upper temperature value, control operation of at least one of the base power-transfer apparatus or the power supply unit based on the measured temperature to:

reduce a power level delivered to the base power-transfer apparatus from a first power level to a second power level that is greater than zero; and

shift losses and dissipate heat in the base power-transfer apparatus or the power supply unit.

2. The wireless power-transfer system of claim 1 , wherein:

the base power-transfer apparatus includes a ferrite layer disposed proximate to the coil; and

the at least one temperature sensor is disposed proximate to the ferrite layer to measure a temperature of the ferrite layer during the operation of the base power-transfer apparatus.

3. The wireless power-transfer system of claim 1 , wherein:

the coil comprises a conductor that follows a path including a plurality of bends; and

the at least one temperature sensor is positioned proximate to one of the plurality of bends.

4. The wireless power-transfer system of claim 1 , wherein the at least one temperature sensor comprises a plurality of temperature sensors including a first temperature sensor disposed proximate to a ferrite layer of the base power-transfer apparatus to measure a first temperature associated with operation of the base power-transfer apparatus and a second temperature sensor disposed at the power supply unit to measure a second temperature associated with operation of the power supply unit.

5. The wireless power-transfer system of claim 1 , wherein the first power level is a nominal full power value, and wherein the power level is reduced by cycling between the nominal full power value and decreasing values of power to decrease the temperature over time.

6. The wireless power-transfer system of claim 1 , wherein the system controller is configured to control the operation of the base power-transfer apparatus or the power supply unit to maintain the measured temperature within a temperature range defined by the upper temperature value and a lower temperature value.

7. The wireless power-transfer system of claim 1 , wherein the system controller is configured to control the operation of the base power-transfer apparatus or the power supply unit by selecting a power mode from a plurality of power modes including a warm-up mode and a cool-down mode, the system controller further configured to:

increase power delivered to the base power-transfer apparatus from the power supply unit in the warm-up mode; and

decrease power delivered to the base power-transfer apparatus from the power supply unit in the cool-down mode.

8. The wireless power-transfer system of claim 1 , wherein the system controller is configured to control the operation of the base power-transfer apparatus or the power supply unit by varying a phase and timing of an input to the coil to shift losses from the coil in the base power-transfer apparatus to the switching and power electronics in the power supply unit.

9. The wireless power-transfer system of claim 1 , wherein the system controller is configured to control the operation of at least one of the base power-transfer apparatus or the power supply unit by:

communicating with a vehicle system controller of a vehicle power-transfer apparatus at least partially aligned with the base power-transfer apparatus;

transmitting a request to the vehicle system controller to increase a third power level of the vehicle power-transfer apparatus to shift the losses from the base power-transfer apparatus to the vehicle power-transfer apparatus and maintain power transfer between the base power-transfer apparatus and the vehicle power-transfer apparatus that is at a level that is the same or higher than as before reducing the power level of the base power-transfer apparatus from the first power level to the second power level.

10. The wireless power-transfer system of claim 1 , wherein the first power level comprises a nominal full power value and the second power level comprises approximately 50% of the nominal full power value.

11. A method of controlling power transfer between a base power-transfer apparatus and a vehicle power-transfer apparatus, the method comprising:

measuring a temperature of at least one component of the base power-transfer apparatus or the vehicle power-transfer apparatus by using at least one temperature sensor;

comparing the measured temperature to a temperature range defined by a lower temperature value and an upper temperature value;

determining that the measured temperature is greater than the upper temperature value; and

responsive to the determining, controlling operation of the at least one component of the base power-transfer apparatus or the vehicle power-transfer apparatus by reducing power delivered to the at least one component from a first power level to a second power level that is greater than zero.

12. The method of claim 11 , wherein the at least one component comprises a power supply unit or a ferrite layer of the base power-transfer apparatus.

13. The method of claim 11 , wherein:

the at least one component includes a coil comprising a conductor that follows a convoluted path including plural bends;

the at least one temperature sensor is disposed proximate to one of the bends; and

the method further comprises using the at least one temperature sensor to measure the temperature associated with the coil.

14. The method of claim 11 , wherein the at least one component comprises a vehicle control unit or a ferrite layer of the vehicle power-transfer apparatus.

15. The method of claim 11 , further comprising:

subsequent to reducing the power delivered to the at least one component, determining that the measured temperature is less than the lower temperature value; and

responsive to the determining, controlling the operation of the at least one component by increasing the power level of the at least one component from the second power level to the first power level.

16. The method of claim 11 , further comprising maintaining the measured temperature within the temperature range by shifting losses to dissipate heat when the temperature exceeds the upper temperature value or when the temperature is less than the lower temperature value.

17. The method of claim 11 , wherein controlling the operation of the at least one component includes selecting a power mode based on the measured temperature, the power mode selected from:

a full-power mode in which the at least one component operates with full power;

a warm-up mode in which power delivered to the at least one component is increased to cause the temperature of the at least one component to increase; and

a cool-down mode in which the power delivered to the at least one component is decreased to cause the temperature of the at least one component to decrease.

18. The method of claim 11 , wherein the first power level is a nominal full power value, and wherein reducing the power delivered to the base power-transfer apparatus comprises cycling between the nominal full power value and decreasing values of power to reduce the temperature over time.

19. The method of claim 11 , wherein the first power level is a nominal full power value, and wherein reducing the power delivered to the base power-transfer apparatus comprises cycling between the nominal full power value and one or more intervals of ramping down the power to reduce the temperature over time.

20. A wireless power-transfer system comprising:

a vehicle power-transfer apparatus of an electric vehicle, the vehicle power-transfer apparatus including a coil configured to convert a magnetic field into an electric current;

a vehicle control unit coupled to the vehicle power-transfer apparatus, the vehicle control unit including switching and power electronics configured to use the electric current to charge a battery of the electric vehicle;

one or more temperature sensors coupled to the vehicle power-transfer apparatus, the one or more temperature sensors configured to measure a temperature of the vehicle power-transfer apparatus; and

a system controller coupled to the vehicle power-transfer apparatus, the vehicle control unit, and the one or more temperature sensors, the system controller configured to:

determine whether the measured temperature exceeds an upper temperature value of a defined temperature range; and

responsive to the measured temperature exceeding the upper temperature value, control operation of at least one of the vehicle power-transfer apparatus or the vehicle control unit by reducing a power level delivered to the vehicle power-transfer apparatus to shift losses and spread heating effects between different components of the vehicle power-transfer apparatus or the vehicle control unit, the power level reduced from a first power level to a second power level that is greater than zero.

21. The wireless power-transfer system of claim 20 , further comprising an additional temperature sensor coupled to the vehicle control unit and configured to measure an additional temperature of the vehicle control unit.

22. The wireless power-transfer system of claim 20 , wherein:

the vehicle power-transfer apparatus includes a ferrite layer disposed proximate to the coil; and

the one or more temperature sensors are disposed on the ferrite layer to measure an additional temperature of the ferrite layer during operation of the vehicle power-transfer apparatus.

23. The wireless power-transfer system of claim 20 , wherein the system controller is configured to:

communicate, via a wireless link, with a base-side system controller that controls operation of a base power-transfer apparatus; and

transmit a request to the base-side system controller to decrease a power level of the base power-transfer apparatus to reduce heat generated at the vehicle power-transfer apparatus.

24. The wireless power-transfer system of claim 20 , wherein the one or more temperature sensors are disposed in one or more high-flux density areas of the vehicle power-transfer apparatus.

25. The wireless power-transfer system of claim 20 , wherein the system controller is configured to:

subsequent to reducing the power level delivered to the vehicle power-transfer apparatus, receive a communication from a base-side system controller of a base power-transfer apparatus, the communication including a request to increase the power level delivered to the vehicle power-transfer apparatus; and

in response to receiving the request, increase the power level delivered to the vehicle power-transfer apparatus from the second power level to the first power level.

26. The wireless power-transfer system of claim 20 , wherein:

the coil comprises a conductor that follows a path including a plurality of bends; and

the one or more temperature sensors includes a temperature sensor positioned proximate to one of the plurality of bends.

27. A wireless power-transfer system comprising:

a coil configured to generate a magnetic field based on an electric current;

ferrite disposed proximate to the coil and configured to direct the magnetic field;

a power supply unit coupled to the coil and configured to drive the coil with the electric current;

a measuring means for measuring a temperature at one or more locations on the ferrite or at the power supply; and

a controlling means for varying operation of the coil or the power supply based on the measured temperature and a defined temperature range, the controlling means varying the operation in response to the measured temperature exceeding an upper temperature value of the defined temperature range by reducing a power level delivered to the coil or the power supply from a first power level to a second power level that is greater than zero.