NPC三电平逆变器中点平衡SVPWM简化算法研究

A Simplified SVPWM Algorithm Research Based on the Neutral-point Voltage Balance for NPC Three-level Inverter

针对中点箝位型(NPC)三电平逆变器中,采用传统空间矢量脉宽调制(SVPWM)运算量大,不利于实时控制的缺点,提出一种基于60°坐标系的SVPWM算法,通过坐标变换使矢量坐标归一化为整数,对参考矢量坐标分别向上、向下取整来确定基本矢量,并利用伏秒平衡原理计算其作用时间;引入开关状态方程,选取适当自由度,实现对中点电压的控制。实验结果证明了此方法无需对参考矢量进行扇区判断,避免了复杂的三角运算,较传统算法节省了计算量,实现了对三电平逆变器的实时控制,并减小了电机的转动脉动。

Aiming at the problems that a lot of calculation exist in the traditional SVPWM algorithm in the three-level NPC inverter,which is difficult to realize real-time control,a SVPWM algorithm based on 60° coordinate system is proposed.The space vector coordinates is integer by a simple coordinate transformation,and the basic vectors are achieved by the reference vector coordinate upward and rounded down respectively, whose effective time is calculated by the principle of voltage-seconds balance.The switching state equation is introduced to control the neutral-point voltage balance, the appropriate degrees of freedom is chosed.The experimental results show that this algorithm has less calculation than the traditional algorithm with requirement no judgment of sectors and avoidance the complex trigonometric equations for real-time control of three-level inverter, and reduces the rotation of the motor pulse.