T型三电平与两电平功率开关器件损耗计算与分析

Calculation and Analysis of the Loss of Power Switching Devices of Three-Level T-type and Two-Level

研究两种逆变器拓扑的功率开关器件损耗,通过器件特征参数,建立一种同时考虑工作电压、驱动电阻和结温的简单曲线拟合方法,推导出三次谐波注入调制算法下T型三电平和两电平拓扑的损耗计算模型,发现损耗与调制系数、开关频率、功率因数角、输出电流有关。在相同逆变工作条件下,当开关频率大于6.8 kHz时,在全电流范围内可使得T型三电平拓扑比两电平拓扑损耗更小,发挥其三电平优势。该损耗研究理论可推广至其他拓扑结构,为并网逆变器设计、效率提升奠定基础。

The loss of power devices in two inverter topologies was studied. Through the device’s characteristic parameters, a simple curve fitting method was established which considered the influence of operating voltage, driving resistance and junction temperature. The loss calculation model of the three-level T-type and two-level inverter was derived under the third harmonic injection PWM(THIPWM) strategy. It is found that the power loss is related to the modulation factor, switching frequency, power factor angle and the output current. Under the same inverter operating conditions, when the switching frequency is more than 6.8 kHz, the loss of T-type topology can be smaller than two-level topology within all current extent, reflecting the three-level superiority. The study of power loss can be extended to other topologies, lay the foundation of design and increase the efficiency of the grid-connected inverter.