T型三电平逆变器无差拍电流预测和中点平衡控制方法

Deadbeat predictive current and neutral voltage balancing control method parallel three-level T-type inverters

根据T型三电平逆变器的特点,提出一种新型无差拍预测控制方法。和传统无差拍方法相比,该方法能够提高电流跟踪的速度和精度,在相同开关频率下可使输出并网电流畸变减少。为了进一步解决T型三电平逆变器固有的中点不平衡问题,提出一种新型SVPWM调制策略实现中点平衡控制。在分析T型三电平逆变器模型的基础上,根据上侧电容和下侧电容电压的差值,通过增加或者减少小矢量作用时间实现中点电位平衡控制。实验结果验证了所提出的新型无差拍控制和SVPWM调制策略可以同时实现并网电流快速跟踪和中点平衡控制问题。

A new deadbeat predictive current control method is proposed according to the characteristics of three-level T-type inverter（3LT^2I）. Compared to the conventional deadbeat method, this method can fast track the current and reduce the THD of the output current. In order to solve the problem of the neutral-point potential（NP） unbalancing, the novel SPWM method is proposed to realize the NP balance. Based on the model of the 3LT^2 I, the time of the conventional symmetric SVPWM is changed by adding or subtracting the minimum dwell time based on the upper and lower capacitor voltage. Experiment results from a prototype inverter prove that both NP balance control and fast grid-connected current tracking can be realized using the novel deadbeat controller and SVPWM strategy.