基于I-DPWM的三电平中点钳位光伏逆变器漏电流抑制方法

对于三电平中点钳位光伏逆变器，基于断续脉宽调制(discontinuous pulse width modulation, DPWM)并通过选择特定矢量进行钳位控制的方法，存在矢量分解计算时间长、注入共模电压分量和漏电流过大等不足。对此，提出了一种基于I-DPWM的三电平中点钳位光伏逆变器漏电流抑制方法。通过计算各类DPWM等效调制波来解析注入的低频共模电压分量。针对低频共模电压分量最小的DPWM1，在低频共模电压不连续点注入新的零序分量，通过减小低频共模电压来抑制漏电流幅值。同时，采用载波实现DPWM，免去了复杂的矢量运算。最后，在Matlab/Simulink平台建立了20 kW三电平中点钳位光伏逆变器的仿真模型，同时结合所设计的125 W实验样机验证了所提方法的有效性。

Leakage current suppression method of a three-level neutral point clamp photovoltaic inverter based on I-DPWM

For three-level neutral point clamped photovoltaic inverters, a suppression method based on discontinuous pulse width modulation (DPWM) and with the selection of a specific vector for control, has shortcomings such as long calculation time of vector decomposition, large injection common-mode voltage component and large leakage current. In this paper, a leakage current suppression method based on I-DPWM for a three-level neutral point clamped photovoltaic inverter is proposed. The injected low-frequency common-mode voltage component is analyzed by calculating various DPWM equivalent modulation waves. Aiming at DPWM1, which has the lowest low-frequency common-mode voltage component, a new zero-sequence component is injected at the low-frequency common-mode voltage discontinuity point, and the leakage current amplitude is suppressed by reducing the low-frequency common-mode voltage. At the same time, a carrier is adopted to realize the DPWM, without complex vector operation. Finally, a simulation model of a 20 kW three-level neutral point clamp photovoltaic inverter is established on the Matlab/Simulink platform, and the effectiveness of the proposed method is verified by combining with the designed 125 W experimental prototype.