单相特定谐波消除脉宽调制高频逆变器的死区补偿策略

由于死区时间的设置,开关管不能以理想时刻开断,导致逆变器输出波形发生畸变。为改善波形,需要进行死区补偿。以提前关断方式为例,深入分析高频逆变器在消除特定谐波脉冲宽度调制控制时,死区对特定谐波消除脉宽调制(SHEPWM)波的影响,给出了基波幅值和总谐波畸变率随死区时间的变化曲线。提出在正半周期内只对开关管S2和S3的触发脉冲设置死区,在负半周内只对S1和S4的触发脉冲设置死区的死区补偿策略,详细分析死区补偿阶段开关管及相应续流二极管的电流的工作状态。以功率MOSFET为例分析开关管的开通关断过程,并给出了死区时间设置的经验公式。最后,搭建仿真模型和硬件平台对所提死区补偿策略进行仿真和实验,结果表明该死区补偿策略有效缓解了由于死区所造成的波形畸变。

Study of Dead-Time Compensation Strategy in Selective Harmonic Elimination PWM Inverter

Due to the dead-time setting, the switch tube can't break at ideal moment, which leads to the output waveforms distortion of inverter. In order to improve the waveform, dead-time effect needs to be compensated. Taken advance-off mode as an example, the influence of dead time on selective harmonic elimination pulse width modulation (SHEPWM) was analyzed in this paper. The curves of amplitude and total harmonic distortion (THD) at different dead time were given. A novel dead time compensation strategy was proposed. Set dead time on the S2 and S3 trigger pulse in the positive half cycle, and on S1 and S4 trigger pulse in the negative half period. The current of the switch tube and the corresponding continuous current diode during the dead-time compensation phase was analyzed in detail. Taken power MOSFET as an example, the switch process was analyzed. The empirical formula of the dead time was provided. Finally, simulations and experiments were carried out on the simulation model and hardware platform. The results show that the compensation strategy can effectively alleviate the waveform distortion caused by the dead time.