The Direct Charge Model and Control of Inverter Power Supply in Mixed Conduction Mode

Abstract

The inverter operating in the mixed conduction mode (MCM) can take advantages of both the discontinuous conduction mode (DCM) to reduce the switching loss, and the continuous conduction mode (CCM) to limit the current stress of the power switches. When the inverter is operating in CCM, a state average model based on capacitor voltage and inductor current is usually established. However, when the inverter is working in DCM, the same kind of mathematical model has a high degree of nonlinearity. For the hybrid conduction mode, this paper proposes a unified direct charge model using the inductor charge as the state variable, which makes the control of the inverter simple and convenient. Based on the model, this paper proposes a direct charge control strategy combining with the load current feedforward, which achieves excellent performance. Simulation and experimental results verified the excellent performance of the control method.