计及IGBT暂态特性的PWM逆变电路输出电压谐波分析

PWM逆变器以结构简单、控制灵活等优点广泛地应用于电力系统之中,但其IGBT暂态特性易受结温影响,导致PWM逆变电路输出电压易受温度影响而产生畸变。针对上述问题,文中首先确定IGBT暂态特性与结温关系;通过贝塞尔函数推导出IGBT开关延迟时间与PWM逆变电路输出电压谐波的数学关系;最后在Matlab/Simulink环境下搭建计及IGBT暂态特性的PWM逆变电路模型进行仿真。理论分析与仿真结果表明,IGBT开关延迟时间呈正温度系数关系;在计及IGBT开关延迟的情况下,PWM逆变电路输出电压新增直流与高次谐波成份,谐波总含量增大,电压总畸变率升高。

Output Voltage Harmonic Analysis of PWM Inverter Circuit Considering IGBT Transient Characteristics

The PWM inverter is widely used in power systems due to its simple structure and flexible control. However, its IGBT transient characteristics are susceptible to junction temperature, which causes the output voltage of the PWM inverter circuit to be affected and distorted by temperature. Aiming at the above problems, this paper firstly determines the relationship between IGBT transient characteristics and junction temperature. Then, the mathematical relationship between IGBT transient characteristics and PWM inverter circuit output voltage harmonic is derived by Bessel function. Finally, under the MATLAB/Simulink environment, the PWM inverter circuit model considering IGBT transient switching characteristics is built to simulated. Theoretical analysis and simulation results show that the IGBT switching delay time has a positive temperature coefficient relationship; in the case of IGBT switching delay, the PWM inverter circuit output voltage adds DC and harmonic components, the total harmonic content increases, and the total rate of voltage distortion is rising.