Research on Digital Control of 400Hz Inverter

Digital control is suitable for high-performance 400Hz inverters because of its simple control circuit, strong robustness and good dynamic performance. Considering the efficiency and device characteristics, the frequency modulation ratio of 400Hz inverter is relatively low, which leads to a negative influence on the dynamic performance of the inverter. Meanwhile, the output voltage harmonics of 400Hz SPWM inverter in low frequency band are large because of dead-time effect and digital delay. To cope with these problems, firstly, the influence of dead-time and digital delay is introduced in this paper. Then, the approach which combines reducing switching frequency, adding PR controller with phase compensation and serial harmonic trap is put forward. The dynamic performance and power quality of 400Hz inverter can be improved by the optimization of output filter and control parameters. Theoretical analysis and experimental results verified the proposed control method.