Variable Frequency Phase Shift Modulation and Soft Switching Algorithm for High Frequency Isolated Matrix-Type Inverter

In order to solve the problem of high peak inductor current when the single stage single phase high-frequency isolated matrix-type inverter (HFIMI) operates with the conventional schemes, a variable frequency phase shift (VFPS) modulation is proposed without adding extra auxiliary circuit. The single-stage power conversion structure includes a dc side full bridge inverter and an ac side matrix-type converter (MC). The extended phase shift (EPS) modulation and pulse width modulation (PWM) is combined with the variable frequency modulation to form a hybrid control strategy, which provide linear power control and significantly simplifies the complexity of the controller design. Besides, the high- and low- frequency interleaved control is employed in the MC to reduce the high frequency conduction loss. Under the proposed VFPS strategy, a specified control route with minimum peak inductor current is then developed, along which the HFIMI implements full soft-switching operation in the whole load range with high efficiency. Finally, a 500W prototype was built to experimentally confirm the validity and feasibility of the proposed control strategy.