Design of Single-Switch Inverters for Variable Resistance/Load Modulation Operation

Single-switch inverters such as the conventional class E inverter are often highly load sensitive, and maintain zero-voltage switching over only a narrow range of load resistances. This paper introduces a design methodology that enables rapid synthesis of class E and related single-switch inverters that maintain ZVS operation over a wide range of resistive loads. We treat the design of ClassE inverters for variable resistance operation and show how the proposed methodology relates to circuit transformations on traditional class E designs. We also illustrate the use of this transformation approach to realize 2 inverters for variable-resistance operation. The proposed methodology is demonstrated and experimentally validated at 27.12 MHz in a class E and 2 inverter designs that operate efficiently over 12:1 load resistance range for an 8:1 and 10:1 variation in output power respectively and a 25 W peak output power.