Explicit Design and Analysis of Inductive Clamping Class E Inverters for ZVS Operation with Capacitive Load Impedance

As a kind of nonlinear power amplifier, class E inverters has the advantages of ultra-high efficiency, high power density, simple circuit topology and low-side driving, but it's highly load sensitive, only maintains zero-voltage switching (ZVS) over a narrow range of load impedance, and is susceptible to switching overvoltage when the load varies. With the inductive clamping circuits, class E inverter has all advantages mentioned above and in addition has minimum spurious oscillations and a wide range of load maintaining ZVS. This paper proposed explicit design of inductive clamping class E inverter (ICCEI) and revealed the mechanism of inductive clamping circuit through steady-state response and transient response. The ICCEI with and without clamping power supply have been built and tested. The efficiency of these can be up to 91.7% and 90.23% at nominal operating conditions, respectively. The experimental results show that the two inductive clamping Class E inverters are able to maintain ZVS operation under the capacitive load condition without using any control strategy or complicate matching networks and quickly reach steady-state in one cycle when load varies, effectively avoiding switching overvoltage.