System and method of wireless power supply
A system and method for sensorless coil detection that exploits a dead-time effect in a WPT inverter as an indicator of presence of a receiver. In one embodiment, a system described herein may be configured to detect arrival of a moving receiver prior to alignment of the moving receiver with the transmitter for power transmission.
1. An off-board transmitter for wirelessly providing AC power to an electric vehicle (EV) or a plug-in electric vehicle (PEV), the transmitter comprising:
a DC voltage source;
an inverter configured:
to receive a DC voltage from the DC voltage source, and
convert the DC voltage to a high-frequency AC voltage;
a primary coil configured to wirelessly transmit the high-frequency AC voltage;
a notch detector configured to:
sense the high-frequency AC voltage as a sensing signal, and
detect notches in the sensing signal caused by varying coupling between the primary coil and a pick-up coil of the EV/PEV, the pick-up coil configured to receive the high-frequency AC voltage when the primary coil and the pick-up coil are disposed adjacent to each other; and
driver circuitry configured to:
apply first driving signals to the inverter such that a first deadtime is provided between complementary switching instances of the inverter phase legs, and set a level of operating frequency, provided by the drive signal, to a first level, and set a level of the DC voltage, provided by the DC voltage source to the inverter, to a first level;
monitor the notch detector to determine whether notches have been detected, and if so, generate second driving signals corresponding to a second deadtime shorter than the first deadtime, and set the level of the frequency to a second level, and set the level of the DC voltage to a second level larger than the first level, and after a predetermined time interval, regenerate the first driving signals, and reset the level of the DC voltage to the first level.
2. The transmitter of claim 1 , wherein the notch detector comprises an operational amplifier.
3. The transmitter of claim 1 , wherein a frequency of the fundamental component of the high-frequency AC voltage is 22 kHz or 85 kHz.
4. The transmitter of claim 1 , wherein the driver circuitry comprises a microcontroller, an ASIC, or an FPGA.
5. A wireless power transfer (WPT) system for wirelessly providing AC power to an electric vehicle or a plug-in electric vehicle, the WPT system comprising:
the off-board transmitter of claim 1 ; and
an on-board receiver comprising a pick-up coil.
6. The WPT system of claim 5 , for which:
a WPT system power rating of 100 kW, and
the second level of the DC voltage is in a voltage range of 350-800 V.
7. The WPT system of claim 6 , wherein the first level of the DC voltage is in a voltage range of 5-50V.