悬浮电容式五电平变频PWM控制器设计

Development of a novel PWM controller for flying capacitor 5-level inverter

为了解决悬浮电容式多电平逆变器控制中所存在的电压平衡控制困难和冗余开关选择复杂的问题,采用一种直接脉冲宽度调制(PWM)算法和以电压级差为控制目标的电压平衡策略,设计了一台基于数字信号处理芯片(DSP)和现场可编程门极阵列(FPGA)的悬浮电容式五电平变频PWM控制器。该控制策略具有物理概念清晰、实现简单的突出优点。给出了所采用的直接PWM算法的原理、控制器设计的方案以及该控制器在380V/8kW悬浮电容式五电平逆变器样机上的电压、电流实验结果与频谱分析结果。实验结果表明:该设计方案具有理想的电压平衡能力和良好的输出谐波性能。

This paper introduces a pulse width modulation (PWM) controller based on FPGA and DSP for flying capacitor 5-level inverters. The controller employs a direct PWM method and bias error control to solve the balance control problem of the flying capacitor voltage and the complexity of finding redundant switching states. The control strategy is simple and easily understood. This paper discribes the PWM control strategy principle, the controller design, and the experimental results. The harmonic of the output voltage and current is low. The experimental results also verify the validity of the balance control of the flying capacitor voltage.