混合十三电平逆变器调制策略及功率均衡方法

Hybrid 13-level inverter modulation strategy and power equalization method

混合多电平逆变器因其能输出更多电平数且使用的开关器件较少而得到广泛应用,但对电压比为3∶1∶1∶1混合级联H桥十三电平逆变器使用传统的载波移幅调制(phase disposition pulse width modulation,PD-PWM)策略,各单元的功率并不均衡。为了达到功率均衡的目的,文中针对混合十三电平拓扑提出了一种改进的混合调制方法,并在此基础上,进一步重构PD调制下的三角载波和调节高压单元的输出脉冲,在实验室条件下,以调制度0.9为例,3个低压单元L_(1)、L_(2)、L_(3)的开关损耗分别为4.6、4.4、4.2 W,开关损耗基本相等。L_(1)、L_(2)、L_(3)输出功率基本一致,高压单元H_(1)输出功率为51.7 W,3个低压单元功率均为17.2 W,高低压单元输出功率比接近3∶1。仿真得到3个低压H桥单元的开关损耗相同,4个单元的功率均衡,高压和低压部分的功率开关分别工作在基频和高频状态,谐波特性良好。

The hybrid multilevel inverter is widely used because it can output more levels and uses fewer switching devices.However,the traditional phase disposition pulse width modulation(PD-PWM)strategy is used for hybrid cascaded H-bridge 13-level inverters with a voltage ratio of 3∶1∶1,and the power of each unit is unbalanced.In order to achieve the goal of power equalization,an improved hybrid modulation method for the hybrid 13-level topology is proposed.Based on this method,it further reconstructs the triangular carrier under PD modulation and adjusts the output pulse of the high-voltage unit.Under laboratory conditions,taking the modulation degree of 0.9 as an example,the switching losses of the three low-voltage units L_(1),L_(2),and L_(3) are 4.6 W,4.4 W,and 4.2 W respectively.The switching losses are basically equal.The output power of L_(1),L_(2),and L_(3) is basically the same.The output power of high-voltage unit H_(1) is 51.7 W,and the power of the three low-voltage units is 17.2 W.The output power ratio of high-voltage and low-voltage units is close to 3∶1.The research shows that the switching losses of the three low-voltage H-bridge units are the same and the power of the four units is balanced.The power switches of the high-voltage and low-voltage parts work at the fundamental frequency and high frequency respectively,and the harmonic characteristics are good.