有源钳位三电平变频器及其结温平衡控制

传统中点钳位(NPC)三电平变频器存在功率器件结温不平衡的缺点,严重限制了变频器容量的提升,采用有源钳位(ANPC)三电平拓扑可平衡功率器件的结温。本文对ANPC三电平变频器的开关状态及其换流方式进行了分析,并给出了功率器件的损耗和散热模型。介绍了ANPC三电平变频器的两种PWM方式,在此基础上提出了一种结温平衡控制方法。实验结果表明,该方法能够随着调制度的变化动态改变PWM方式1和方式2的工作比例,实现结温平衡控制。相比于NPC三电平变频器,ANPC在逆变和整流模式下的容量可分别提高23.1%和33.3%,具有较高的工程应用价值。

Active Neutral Point Clamped Three-Level Converter and Its Junction Temperature Balancing Control

Traditional neutral point clamped(NPC) three-level converter has a drawback of unbalanced junction temperatures among the power devices,which severely limits the converter’s capacity.While the Active NPC(ANPC) three-level has the potential to overcome this drawback and obtanins an even distribution of junction temperatures.In this paper,the switching states and commutations of ANPC are analyzed,and the loss and heat dissipation model of power devices are given as well.Furthermore,two pulse width modulation(PWM) strategies of ANPC are introduced,based on which a novel junction temperature balancing control method is proposed.Experimental results demonstrate that the proposed method could adjust the operating proportion dynamically between PWM type 1 and type 2 under different modulation indexes,and thus the balanced junction temperatures can be achieved.Compared to NPC three-level converter,ANPC has the ability to raise its capacity of 23.1% and 33.3% respectively under inverter and rectifier operation modes.So the ANPC three-level converters are more competitive for engineering applications.