The infeasibility of self-regulating constant-current-fed class E power inverters

Because of their high operating efficiency, class E circuits have been shown to be useful in high-frequency power inverters and converters. Typical circuits are constant-fed, i.e. they require an RF choke in the DC-feed line, and must obtain load regulation by means of appropriate feedback control. A class E inverter with finite DC-feed inductance that provides perfect load regulation without feedback control has been suggested. However, such class E circuits generally have higher sensitivities to component variations (except load resistance) than do their constant-current-fed counterparts. Thus, the possibility of load-independent operation of constant-current-fed class E inverters is of interest. The authors show that there is no way to configure constant-current-fed E inverter so that it will exhibit load-independent properties except for a trivial circuit with zero output voltage