两电平逆变器半周期对称SHEPWM方法

Half-cycle symmetry SHEPWM method for two-level inverter

提出了"关于正负2个半周期镜对称"和"关于T/2点奇对称"2种PWM波对称方式,以半周期内20个开关切换角为例,通过对两电平逆变器特定谐波消除脉宽调制(SHEPWM)非线性方程组的建立、初值选择和求解,详细研究了两电平逆变器的SHEPWM方法。为了说明半周期对称SHEPWM问题具有更多解的特点,求取了很多组有效数值解,并以抽样点数值解和调制比在全范围内解的变化轨迹的形式列举了其中8组解。在调制比为0.8的情况下,对抽样点数值解进行了仿真与实验研究,仿真与实验结果一致,证明了所提方法的有效性与实用性。

Two half-cycle symmetry SHEPWM（Selected Harmonic Elimination Pulse Width Modulation） schemes are proposed for two-level inverter：positive-negative symmetry and T/2 point symmetry. As an example,the SHEPWM nonlinear equations of two-level inverter with twenty switching points per half-cycle are established and solved to thoroughly investigate the SHEPWM schemes. As the half-cycle symmetry SHEPWM scheme has multiple groups of effective solution,eight of them are listed to show the variation trajectories of its solution and modulation rate covering whole range. Simulation and experiment are carried out for two groups with modulation rate of 0.8,and the conformity of experimental results to simulative results proves the validity and practicability of the proposed schemes.