Analysis of Inductor Current for Series Resonant Tank at Different Practical Operating Conditions

Class-D half-bridge power amplifiers (PA) are used to drive the primary coil of a coupled wireless power transfer (WPT) system. We analyze the primary inductor current of cases such as off-resonant operation, overtuned- and undertuned-capacitor operation, and effects due to finite rise and fall times. We also analyze the case with off-resonant Zero Voltage Switching (ZVS) tank. SPICE simulations validate all the analytical calculations with errors smaller than 2%.