T‐type pulse width modulation controlled three‐level circuit is the mainstream topology in current medium power distributed PV inverters, charging station and active power filter system with the advantages of high equivalent switching frequency, high efficiency, small filter inductance and small grid current harmonic. Aiming at the inherent problems of midpoint voltage fluctuation and complex of the traditional three‐level space vector pulse width modulation (SVPWM) scheme of a three‐level T‐type rectifier, a new equivalent method of SVPWM strategy used in three‐level converter based on acting time equivalence was proposed, which needs no trigonometric function, irrational operation, and complex coordinate transformation. By the means of rotating the target vector in other sectors to the first sector, the dwell time of vectors can be calculated by the unified formula, and the formula for calculating the dwell time is deduced based on two levels SVM. Then, the control problems of the neutral‐point voltage balance in T‐type three‐level converter topology are analyzed and studied. Through the PI control of electric charge of one capacitor, the neutral‐point voltage can be kept to be half of the DC supply voltage stably. To verify the correctness and effectiveness of the proposed control strategy, a complete simulation model and experimental prototype platform under the digital control is established. The results show that the implementation of this method is very simple and it could decrease calculation error and keep the neutral point potential balance, which makes the results more accurate. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中文翻译：

---

基于简化的三级SVPWM调制方案和中性点电势平衡的三级T型并网转换器的研究

T型脉宽调制控制的三电平电路是当前中功率分布式光伏逆变器，充电站和有源滤波器系统中的主流拓扑，具有等效开关频率高，效率高，滤波器电感小和电网电流谐波小的优点。 。针对三电平T型整流器的传统三电平空间矢量脉宽调制（SVPWM）方案的中点电压波动和复杂性等固有问题，基于三电平转换器的SVPWM策略的一种新的等效方法是基于三电平T型整流器。提出了一种等效于作用时间的方法，该方法不需要三角函数，无理运算和复杂的坐标变换。通过将其他扇区中的目标向量旋转到第一个扇区，可以通过统一的公式来计算向量的停留时间，并基于两级支持向量机推导计算停留时间的公式。然后，对T型三电平变流器拓扑中的中性点电压平衡的控制问题进行了分析和研究。通过对一个电容器的电荷进行PI控制，中性点电压可以稳定地保持为直流电源电压的一半。为了验证所提出控制策略的正确性和有效性，建立了数字控制下的完整仿真模型和实验原型平台。结果表明，该方法的实现非常简单，可以减少计算误差，保持中性点电位平衡，使计算结果更加准确。©2020日本电气工程师学会。