Wireless power transfer method, circuit and apparatus

A method for wirelessly providing power to an underwater light emitting diode (LED), the method comprising:

• receiving, with a wireless power transmitter comprising a first rectifier, a driver and a first resonant tank, an input voltage via a cable, the input voltage being an alternate current (AC) voltage and having a first frequency;
• rectifying the input voltage with the first rectifier to generate a first rectified voltage at an output of the first rectifier, wherein a first filtering capacitor is coupled to the output of the first rectifier;
• powering the driver with the first rectified voltage, the driver having an input coupled to the output of the first rectifier and an output coupled to the first resonant tank, the first resonant tank comprising a transmitting coil;
• wirelessly transmitting power by driving the first resonant tank, via the driver, with a driving voltage having a second frequency that is higher than the first frequency, wherein the driving voltage has a sinusoidal envelope at the first frequency and approximates a square-wave at the second frequency;
• wirelessly transmitting power by driving the first resonant tank with the driving voltage;
• receiving the wirelessly transmitted power with a second resonant tank of a wireless power receiver to generate a receiver voltage, the second resonant tank comprising a receiving coil;
• rectifying the receiver voltage with a second rectifier to generate a second rectified voltage at an output of the second rectifier, the second rectifier being different than the first rectifier, wherein a second filtering capacitor is coupled to the output of the second rectifier;
• generating a direct current (DC) voltage from the second rectified voltage with a switched-mode power supply (SMPS);
• and
• powering the underwater LED with the DC voltage.