多相H桥逆变器支撑电容电流计算

Calculation of DC-link Capacitive Current in Multi-phase H-bridge Inverter

直流支撑电容电流计算是变频器设计的一个关键步骤,现有方法多是针对传统的三相变频器展开,鲜有关于多相变频器的相关计算研究。针对直流侧并联型多相H桥逆变电路拓扑和SPWM的调制方式,采用开关函数法对其直流支撑电容电流有效值进行了分析计算,并给出该种电路拓扑下适用于任意有限相逆变器的直流支撑电容电流有效值计算公式,分析了逆变器相数、调制比和功率因素对电容电流有效值的影响。仿真与实验证明,该计算方法准确性较高,使用所提出的公式可以有效地实现多相H桥逆变器直流支撑电容电流计算。

The calculation of DC-link capacitive current is one key step in inverter design. However, most of the existing methods are designed aiming at the traditional three-phase inverters, and there is few research related to the calculation of multiphase inverters. In light of the DC-side parallel multi-phase H-bridge inverter and the modulation principle of SPWM, the RMS of DC-link capacitive current is calculated using the switch function method, and the formula for calculating the RMS of DC-link capacitive current in any finite-phase inverter with this circuit topology is given. In addition, the effect of the number of phases, modulation ratio and power factor on the RMS of capacitive current is analyzed. Simulation and experimental results showed that this calculation method had higher accuracy, and the proposed formula can effectively realize the calculation of DC-link capacitive current in multi-phase H-bridge inverters.