三电平 DPWM光伏逆变器的中点平衡控制

摘要

传统中点平衡控制方法运用在三电平 DPWM（discontinuous pulse-width modulation）逆变器中会打乱 DPWM的箝位区域，从而使 DPWM策略失效。针对该问题提出了一种新的中点平衡控制方法。此方法在中点电位波动大于正限值时将距离负电平最近的一相箝位于负电平，在小于负限值时将距离正电平最近的一相箝位于正电平，由此推算出调中点电位时刻应注入调制波的零序电压分量。搭建 Simulink 模型及由 DSP 控制器和 Q8构成的半实物仿真实验平台，对所提算法分别进行了离线仿真及硬件在环（hardware-in-the-loop，HIL）仿真实验，证明了所提算法的可行性及有效性。此方法能简单有效地控制中点电位平衡，无需在每个载波周期都进行复杂的计算即可达到控制目的，同时能确保 DPWM低开关损耗的特性。%To solve the problem that the DPWM’s advantage of low switching losses will be destroyed when traditional neutral-point potential balancing methods are applied in DPWM inverters,a new balancing method was developed.The proposed method was implemented by clamping one phase-leg to negative DC-bus when the potential is higher than the positive limit,or positive DC-bus when the potential is lower than the negative limit,according to which the zero-sequence voltage was calculated to balance the neutral-point potential.Then,a Simulink model and a hardware-in-the-loop (HIL) testing platfrom composed of a Q8 model and a DSP controller were built,whose simulation and experiment results were verified the validity and feasibility of the proposed method.This method maintains low switching losses of DPWMand balances the neutral-point potential effectively and more simply,without extra complex calculations in every period of carrier-wave like the traditional method.