一种通用的基于预测控制的二极管钳位型变流器载波调制均压策略

General prediction-based voltage balance method for diode-clamped converters with carrier modulators

直流电容均压控制是二极管钳位型变流器的主要问题。本文以三电平二极管钳位型变流器为例,提出了一种通用的二极管钳位型变流器的载波调制均压策略。该均压策略通过在载波调制器的调制波中注入优化的零序电压来平衡各直流电容的电压。首先,给出了所注入零序电压的通用表达式,分析了零序电压对三电平二极管钳位型变流器中点电位的控制机理;其次,提出了一种基于预测控制的均压算法,计算所需的优化零序电压。仿真和实验结果表明,本文所提均压方法可有效控制三电平二极管钳位型变流器的中点电位,并可方便地扩展到更多电平数的二极管钳位型变流器。

Voltage balance of DC-link capacitors is the key problem of the diode-clamped converter(DCC).In this paper,three-level DCC is taken as an example,and a general carrier-based voltage balance method is proposed,which is characterized by injecting a zero-sequence voltage in the modulation signals.First,a general expression of the injected zero-sequence voltage was given,and the effects of the injected zero-sequence voltages on the neutral point currents were theoretically analyzed.Accordingly,a prediction-based algorithm was proposed to determine the optimal zero-sequence voltage.Simulation and experimental results prove that,with this method,the neutral-point voltage deviations of three-level DCC can be effectively suppressed.Besides,the proposed method can be conveniently extended to multilevel diode-clamped converters with more voltage levels.