混合级联H桥逆变器的新型SHEPWM功率均衡控制策略

Novel SHEPWM power balancing control strategy for hybrid cascaded H-bridge inverter

对于直流侧电压比为1∶1∶2的混合级联H桥逆变器,传统的指定谐波消除脉宽调制法(SHEPWM)存在各单元间输出功率不均衡问题,因此,提出一种双层功率均衡调制策略。首先,通过对消谐方程组中的基波幅值方程表达式进行等效拆分,使2个低压H桥单元的输出电压基波幅值之和与高压H桥单元的输出电压基波幅值相等,实现了高低压H桥单元间的功率均衡,即外层功率均衡。其次,利用逻辑运算的方法对低压单元的初始驱动信号进行逻辑重组,实现2个低压单元间的功率均衡,即内层功率均衡;然后使用改进的实数型遗传算法(IRCGA-2)求出消谐方程组的解,消除指定的谐波,得到高质量的输出电压。最后,通过仿真和实验证明了调制策略的正确性与有效性。

For a hybrid cascaded H-bridge inverter with a DC-side voltage ratio of 1∶1∶2,the traditional SHEPWM method faces an issue of unbalanced output power among different units.To address this issue,a dual-layer power balancing modulation strategy was proposed.In the modulation strategy,power balancing was achieved between high-voltage and low-voltage H-bridge units,referring to as outer-layer power balancing,by equivalently splitting the fundamental wave amplitude equation in the harmonic elimination equation set so that the sum of the output voltage fundamental wave amplitudes of the two low-voltage H-bridge units is equal to the output voltage fundamental wave amplitude of the high-voltage H-bridge unit.Secondly,logical operations was utilized to logically reorganize the initial driving signals of the low-voltage units,achieving power balancing between the two low-voltage units,referring to as inner-layer power balancing.Then,an improved real-coded genetic algorithm(IRCGA-2)was used to solve the harmonic elimination equation set,eliminating specified harmonics and obtaining high-quality output voltage.Finally,simulations and experiments prove correctness and effectiveness of this modulation strategy.