二极管箝位型四电平逆变器的中点电压平衡控制方法  

Neutral-point voltage balance method for diode-clamped four-level inverters

作　　者：王奎[1] 郑泽东[1] 许烈[1] 李永东[1] WANG Kui;ZHENG Ze-dong;XU Lie;LI Yong-dong(State Key Laboratory of Control and Simulation of Power System and Generation Equipment,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学电力系统及发电设备控制和仿真国家重点实验室,北京100084

出　　处：《电机与控制学报》2021年第3期1-7,共7页Electric Machines and Control

基　　金：国家重点研发计划资助(2018YFB0905500)。

摘　　要：二极管箝位型四电平逆变器具有开关器件少、输出电压高、结构紧凑、功率密度高的优点,在中压变频调速领域有很好的应用潜力。针对其母线中点电压平衡问题,提出一种新型载波交叠PWM调制策略,满足伏秒平衡原则。在此基础上进一步提出了一种可平衡母线中点电压的解耦控制方法,将3个母线电容的电压平衡控制分为2个解耦的控制目标:1)上、下母线电容电压的平衡控制;2)中间母线电容电压平衡控制。首先通过零序电压注入的方式实现上、下母线电容电压的平衡控制,其次通过微调PWM脉冲占空比的方式实现母线中间电容的电压平衡控制。研制了一台二极管箝位型四电平逆变器的小功率实验样机并实验证明了该调制策略以及电压平衡控制方法的正确性和有效性。Neutral-point clamped four-level inverter features the advantages of very few active switches,high output voltage,compact structure and high power density,so it has great potential in the medium-voltage variable-frequency motor speed control applications.In order to solve the neutral-point voltage balance problem of diode-clamped four-level converters,a novel carrier-overlapped PWM method was proposed,which satisfies the volt-second balance principle.On this basis,a decoupled neutral-point voltage balance method was proposed,which can be divided into two steps:1)voltage balancing between the top and bottom dc-link capacitors;2)voltage balancing of the middle dc-link capacitor.The top and bottom dc-link capacitor voltages were balanced by zero-sequence voltage injection firstly.Then the middle dc-link capacitor voltage was balanced by adjusting the duty cycles of PWM signals.A low power diode-clamped four-level converter prototype was constructed.Experimental results demonstrate effectiveness of the modulation and voltage balance methods.

关 键 词：中压变频器 二极管箝位型四电平变换器 中点电压平衡 零序电压 载波交叠PWM 伏秒平衡 

分 类 号：TM464[电气工程—电器]