Fault detection and monitoring methods for safe operation of a WEVC system

1. A wireless electric vehicle charging system comprising:

base-side equipment operable to generate a magnetic field for delivery of power to vehicle-side equipment; and

monitoring circuitry coupled to the base-side equipment and configured to:

monitor one or more of voltage, current, or phase associated with operation of the base-side equipment; and

halt generation of the magnetic field in response to a change in the one or more of voltage, current, or phase associated with the operation of the base-side equipment that indicates a fault condition at the vehicle-side equipment that includes a loss of power.

2. The wireless electric vehicle charging system of claim 1 , wherein:

the magnetic field is generated by a base-side coil driven by an alternating current; and

the generation of the magnetic field is halted based on an interruption of the alternating current to the base-side coil.

3. The wireless electric vehicle charging system of claim 1 , wherein the base-side equipment comprises:

a power-factor-correction circuit coupled to a power source and configured to provide a direct current (DC) output;

an inverter coupled to the power-factor-correction circuit, the inverter configured to receive the DC output and provide a high frequency output;

tuning circuitry coupled to the inverter, the tuning circuitry configured to receive the high frequency output and provide an output power signal; and

a coil coupled to the tuning circuitry, the coil configured to receive the output power signal and generate the magnetic field.

4. The wireless electric vehicle charging system of claim 3 , wherein the one or more of voltage, current, or phase is associated with operation of at least one of the power-factor-correction circuit, the inverter, the tuning circuitry, or the coil.

5. The wireless electric vehicle charging system of claim 3 , wherein the monitoring circuitry is configured to monitor power input to the coil.

6. The wireless electric vehicle charging system of claim 3 , wherein the monitoring circuitry is configured to monitor the current between the tuning circuitry and the inverter.

7. The wireless electric vehicle charging system of claim 3 , wherein the monitoring circuitry is configured to monitor the current between the inverter and the power-factor-correction circuit.

8. The wireless electric vehicle charging system of claim 3 , wherein the monitoring circuitry is configured to monitor the current between the power-factor-correction circuit and the power source.

9. The wireless electric vehicle charging system of claim 1 , wherein:

the base-side equipment is configured to generate the magnetic field in response to power requests from the vehicle-side equipment; and

the monitoring circuitry is configured to compare a previous power request from the vehicle-side equipment with data representing present operation of the base-side equipment.

10. The wireless electric vehicle charging system of claim 1 , wherein:

the base-side equipment is configured to generate the magnetic field in response to power requests received from the vehicle-side equipment; and

the monitoring circuitry is further configured to:

determine a known performance value associated with the one or more of voltage, current, or phase associated with operation of the base-side equipment;

predict an expected value of one or more of a second voltage, a second current, or a second phase associated with operation of the vehicle-side equipment based on a combination of a last received power request from the vehicle-side equipment and data representing operation of the base-side equipment; and

halt the generation of the magnetic field in response to a deviation in the known performance value from the expected value that exceeds a threshold value.

11. The wireless electric vehicle charging system of claim 10 , wherein:

the last received power request provides an indication of a vehicle-side power requirement;

the data representing operation of the base-side equipment includes a voltage of a power-factor-correction circuit and a corresponding duty cycle; and

the predicted expected value comprises an expected current of a rectifier of the vehicle-side equipment.

12. The wireless electric vehicle charging system of claim 1 , wherein the monitoring circuitry is configured to:

monitor first current input to a power-factor-correction circuit coupled to a power source;

monitor second current input to an inverter coupled to the power-factor-correction circuit; and

using the first current and the second current in combination to detect the fault condition at the vehicle-side equipment.

13. The wireless electric vehicle charging system of claim 1 , wherein:

the base-side equipment is configured to generate the magnetic field in response to power requests from the vehicle-side equipment; and

the monitoring circuitry is configured to compare a present power request from the vehicle-side equipment with a previous power request from the vehicle-side equipment.

14. The wireless electric vehicle charging system of claim 1 , wherein the monitoring circuitry is configured to:

monitor both the voltage and the current; and

determine the fault condition at the vehicle-side equipment based on a type of change in both the voltage and the current.

15. The wireless electric vehicle charging system of claim 14 , wherein the type of change includes a decrease in a first root mean square (RMS) value of the current and in a second RMS value of the voltage.

16. A method of controlling operation of a wireless electric vehicle charging system, the method comprising:

generating a magnetic field by base-side equipment of the wireless electric vehicle charging system to transfer power to vehicle-side equipment of the wireless electric vehicle charging system;

monitoring one or more of voltage, current, or phase associated with operation of the base-side equipment during power transfer from the base-side equipment to the vehicle-side equipment;

detecting a change in the one or more of voltage, current, or phase indicative of a fault condition in the vehicle-side equipment that includes a loss of power at the vehicle-side equipment; and

halting generation of the magnetic field in response to detecting the change.

17. The method of claim 16 , wherein:

the magnetic field is generated by a coil driven by an alternating current; and

the halting comprises interrupting the alternating current to the coil.

18. The method of claim 16 , wherein the monitoring comprises monitoring voltage across a coil of the base-side equipment that generates the magnetic field.

19. The method of claim 16 , wherein the monitoring comprises monitoring current between tuning circuitry of the base-side equipment and an inverter of the base-side equipment.

20. The method of claim 16 , wherein the monitoring comprises monitoring current between an inverter of the base-side equipment and a power-factor-correction circuit of the base-side equipment.

21. The method of claim 16 , wherein the monitoring comprises monitoring current between a power-factor-correction circuit of the base-side equipment and a power source of the base-side equipment.

22. The method of claim 16 , wherein:

the magnetic field is generated based on first data received from the vehicle-side equipment, the first data indicating a previous power measurement of the vehicle-side equipment; and

the method further comprises comparing the first data with second data representing present operation of the base-side equipment.

23. The method of claim 22 , wherein:

the magnetic field is generated based on first data received from the vehicle-side equipment, the first data indicating a power measurement of the vehicle-side equipment or a power request from the vehicle-side equipment; and

the method further comprises:

determining a known performance value based on the one or more of voltage, current, or phase associated with operation of the base-side equipment; and

predicting an expected value of one or more of a second voltage, a second current, or a second phase associated with operation of the vehicle-side equipment based on a combination of the second data representing present operation of the base-side equipment and one of the power measurement of the vehicle-side equipment or the power request received from the vehicle-side equipment; and

halting generation of the magnetic field is performed in response to a deviation in a known performance value from the expected value that exceeds a threshold value.

24. The method of claim 16 , wherein:

the base-side equipment is configured to generate the magnetic field based on data received from the vehicle-side equipment that indicates vehicle-side power measurements; and

the method further comprises:

receiving first data indicating a first power measurement at the vehicle-side equipment;

subsequent to receiving the first data, receiving second data indicating a second power measurement at the vehicle-side equipment; and

comparing the second power measurement with the first power measurement to determine whether the fault condition has occurred at the vehicle-side equipment.

25. A wireless electric vehicle charging system comprising:

base-side equipment including a coil;

a power-factor-correction circuit configured to receive alternating current (AC) input and provide a direct current (DC) output;

an inverter coupled to the power-factor-correction circuit and configured to use the DC output to provide a power signal; and

monitoring circuitry configured to monitor at least one of voltage, current, or phase associated with signals passing between one or more of the power-factor-correction circuit and a power supply of the AC input, the power-factor-correction circuit and the inverter, or the inverter and the coil, to detect a change indicating a fault condition occurring at vehicle-side equipment of an electric vehicle interacting with a magnetic field generated by the coil.

26. The wireless electric vehicle charging system of claim 25 , wherein the change in the one or more of the voltage, current, or phase is indicative of a loss of power or a disconnection of a battery at the vehicle-side equipment.

27. The wireless electric vehicle charging system of claim 25 , wherein the monitoring circuitry is configured to halt generation of the magnetic field in response to detecting the change.

28. The wireless electric vehicle charging system of claim 25 , wherein the monitoring circuitry is configured to compare a previous power measurement from the vehicle-side equipment with data representing present operation of the base-side equipment.

29. The wireless electric vehicle charging system of claim 25 , wherein the monitoring circuitry is configured to:

monitor a first current associated with the signals passing between the power-factor-correction circuit and the power supply;

monitor a second current associated with the signals passing between the power-factor-correction circuit and the inverter; and

use a combination of the first current and the second current to detect the change indicating the fault condition.

30. The wireless electric vehicle charging system of claim 25 , wherein the monitoring circuitry is further configured to:

monitor both the voltage and the current; and

determine the change indicating the fault condition at the vehicle-side equipment based on a decrease in both a first root mean square value of the current and a second root mean square value of the voltage.