A Constant-Current ZVS Class-E Inverter With Finite Input Inductance

A Class-E inverter with finite input inductance for constant output current and zero-voltage switching (ZVS) over a load range is presented, by combining a Class-E inverter (designed to generate a constant voltage) with a trans-susceptance network (transfers voltage to current and keeps ZVS). Both switching frequency and duty cycle are fixed under load variation. The tradeoffs between the output current value, the effective load range, and the input current ripple are discussed. Same output power capability as the optimum condition in the traditional Class-E inverter is achieved. The expectations were validated by a design switched at 6.78 MHz with 10-V input, 1.4-A output, and 12.6-W maximum output power. ZVS is maintained with 16% output current varying over a 10:1 output power range.