一种基于PWM脉宽动态调节的三电平中点平衡方法

A Three-level Neutral-point Balance Method Based on PWM Pulse Width Dynamic Regulation

提出一种基于PWM脉宽动态调节的三电平中点平衡方法,实现逆变器在低开关频率下的优化PWM高性能闭环控制及其三电平中点平衡控制。由电流观测器提取出电流基波分量,计算动态调节时间和稳态调节电压,避免电流纹波采样参与调节造成的调节时间摆动。通过对各相PWM边沿独立修正,三相PWM脉宽修正之间没有耦合,因此所提方法突破了常规方法中用共模分量调节中点平衡的限制,适用于特定谐波消除(SHE)调制等需查表优化开关角实现同步调制的场合。

Three-level neutral-point balance method based on PWM pulse width dynamic regulation was proposed to realize optimized PWM high-performance closed-loop control and three-level neutral-point balance control of the inverter at low switching frequency. The fundamental current component was extracted from the current observer,and the dynamic regulation time and steady-state regulation voltage were calculated to avoid the regulation time swing caused by the participation of current ripple sampling in regulation.By modifying the edge of each phase PWM independently,there is no coupling among the correction of three-phase PWM pulse width.So the proposed method breaks through the limitation of using common mode component to regulate neutral-point balance in conventional method,which is suitable for specific harmonic elimination(SHE)modulation and other occasions where the switching angle needs to be optimized by looking up tables to realize synchronous modulation.