中点电压主动控制的三电平逆变器非连续PWM调制

A Novel Discontinuous PWM Strategy for Three-Level Inverter with Active Neutral Point Voltage Control

为了减小中点钳位型三电平逆变器的开关损耗,通常采用非连续脉宽调制(DPWM)。但是当使用DPWM时,中点电压上会存在直流偏移和交流纹波,导致逆变器的输出电压上出现低频谐波(LFHs)。针对这一点,提出了低频谐波抑制的DPWM(LFHRDPWM)。当仅采用LFHRDPWM时,中点电压的自平衡能力丧失,故提出了中点电压主动控制(ANPVC),具有ANPVC的LFHRDPWM调制策略可以有效地降低LFHs,且中点电压的偏移可以很好地控制在允许范围内。最后,通过试验结果验证了所提出方法的有效性。

In order to reduce switching loss of neutral-point (NP) clamped three-level inverter,discontinuous pulse width modulation (DPWM) strategy is used usually.But there are DC offset and AC ripple on the NP voltage when DPWM is used,which causes an appearance of low frequency harmonics (LFHs) on the output voltage of neutral-point clamped three-level inverter.Aiming at that,low frequency harmonic reduction DPWM (LFHRDPWM) strategy was proposed.While using LFHRDPWM alone,the self-equilibrium ability of NP voltage is thus lost.Therefore,an active NP voltage control (ANPVC) was also proposed,and the LFHs can be reduced and the neutral-point voltage offset can be well controlled within allowable range when LFHRDPWM with ANPVC is used.Finally,the effectiveness of the proposed method was verified by the experimental results.