基于ZVS变频控制的Si/SiC混合ANPC逆变器损耗评估

Evaluation of Different Si/SiC Hybrid ANPC Inverters Based onVariable Frequency ZVS Control

零电压开通变频控制(variable frequency controlled zero-voltage-switching,VF-ZVS)可在无辅助电路条件下实现零电压开通(zero-voltage-switching,ZVS),进一步提升碳化硅MOSFET逆变器的功率密度。但在三相有源中点钳位逆变器(active-neural-point-converter,ANPC)中,全功率器件ZVS会大幅增加输出电感电流纹波,改变ANPC逆变器的电流续流路径,影响SiC器件损耗分布特征。论文建立电流纹波关于矢量作用时间的分段数学表达式,提出计及电流纹波的SiC器件损耗建模方法,表征VF-ZVS控制下电流纹波对开关管损耗特性的影响规律。进一步,分析VF-ZVS控制下2SiC、4SiC I和4SiC II 3种典型混合ANPC拓扑的新增工作模态特性;利用所提出的损耗模型,评估在不同调制度、全功率等级下上述3种混合拓扑的开关损耗、通态损耗和损耗分布均衡度,并通过6kW SiC实验平台,在不同功率等级下实验验证了SiC器件损耗模型和3种混合拓扑损耗评估结果的正确性。

The variable frequency controlled zero-voltageswitching(VF-ZVS)can achieve zero-voltage-switching(ZVS)without auxiliary circuit,and can further improve the efficiency and power density of SiC MOSFET inverter.But in three-phase Active-neural-point-converter(ANPC),the current ripple will be dramatically increased if all the power switches achieve the ZVS,which changes the path of current,and influences the loss distribution characteristics.In this paper,the piecewise mathematical expression of the current ripple about the vector function of time is established,and the loss modeling method of SiC MOSFET including the current ripple is proposed.The influence law of the current ripple on the MOSFET’s loss characteristics under the control of VF-ZVS is characterized.Furthermore,the newly added commutation processes of 2SiC,4SiC I and 4SiC II inverter are analyzed under VF-ZVS control.The proposed loss model is used to evaluate the switch loss,conduction loss and loss distribution equalization of the three hybrid topologies under different degree of modulation and power levels.The correctness of the SiC MOSFETS’s loss model and the loss evaluation results of the three hybrid topologies can be verified experimentally with the 6kW SiC experimental platform under different power levels.