Efficient deactivation of unused LCC inverter for multiple transmitter wireless power transfer

The study addresses the difficulties in deactivating an unused transmitter (TX) element for a multiple-transmitter wireless power system that is driven by LCC resonant inverters. One difficulty of TX deactivation is a high-level of unwanted circulating current in unused TX coil, which increases the losses in unused TX. To suppress the unwanted current without the aid of high-voltage isolated switches and detuning capacitors, it is proposed that low-side switches in LCC bridge should be constantly turned on. The other difficulty is the runtime detuning of LCC resonant inverter in response to the activation or deactivation status of adjacent TX coil, which degrades the LCC inverter efficiency. A tuning switch and capacitor cannot directly be inserted at the LCC resonant path due to high-voltage stress and complex driving scheme. Instead, this study proposes a loop that adjusts the effective inductance of the TX coil with low-voltage stress and easy gate driving, thereby increasing the LCC inverter efficiency. The loop also provides an additional power path towards the receiver so that the coil-to-coil efficiency is also increased.