三相三电平逆变器的零共模电压空间矢量调制技术研究

Research on Space Vector Modulation with Common-mode Voltage Elimination for Three-phase Three-level Inverters

针对三相三电平逆变器实现零共模电压输出的主要调制方式,即空间矢量调制消除共模电压SVMCME进行研究。首先,为减小七段式SVMCME产生的开关损耗,提出一种五段式SVMCME的调制方式,并对调制比的变化做出详尽的解释。其次,对正弦脉冲宽度调制消除共模电压SPWMCME和SVMCME的等效性在理论上进行证明和仿真验证,以简化控制算法。无论是五段式SVMCME还是七段式SVMCME都可以用注入零序电压分量的SPWMCME来等效。最后,仿真和实验分析比较了3种调制方式在共模电压、开关损耗、总谐波畸变率THD和电磁干扰EMI等方面的性能,相关的技术能够有效地抑制三相系统中的共模噪声。

The typical modulation to achieve zero common mode voltage output for three-phase three-level inverters is space vector modulation common-mode elimination （SVMCME）, which was taken into research in this paper. Firstly, five- segment modulation of SVMCME was proposed to reduce the switching losses caused by seven-segment SVMCME. Additionally, explanation of the variation of modulation index was provided in detail. Meanwhile the theoretical derivation and validation of simulation results successfully clarified the inherent relationship between sinusoidal pulse width modulation common-mode elimination （SPWMCME） and SVMCME to simplify the control algorithm. Bothfive-segment SVMCME and seven-segment SVMCME can be equivalently realized by injecting zero sequence voltage into balanced three-phase voltage reference of SPWMCME. Finally, simulation and experimental results evaluated the three PWM methods＊ performance, including common mode （CM） voltage, switching losses, total harmonics distortion （THD） and elec-tromagnetic interference （EMI）. Related technologies can success-fully reduce the common mode （CM） noise in three-phase systems.