SiC/Si Hybrid ANPC Five-level Inverter Topology And Control Strategy

Active neutral-point clamp(ANPC)five-level inverter has the advantages of low total investment and operation loss,high output voltage level,low voltage withstand requirement of Semiconductor power components,high power density and low harmonic content.In the high voltage conversion field,high voltage distributed new energy generation system and other fields are very popular.In recent years,due to characteristics of "high voltage withstand","high frequency" and "low conduction resistance",wide band gap semiconductor SiC devices can significantly improve the performance of power electronic converters,which has been widely concerned by experts and scholars at home and abroad.However,the high price of SiC devices becomes the key bottleneck of its promotion and application,which seriously restricts the upgrading of power electronic equipment.In this paper,based on the in-depth analysis of the working mechanism of ANPC five-level inverter,SiC MOSFET device is mixed with Si IGBT device to construct a new SiC/Si device hybrid five-level inverter topology.The research of SiC/Si hybrid ANPC five-level inverter topology and high performance control technology has important application value in industrial and technology upgrade of traditional power electronic devices.1.On the basis of fully investigating the modulation strategy of multilevel inverter and the analysis of mixed topology loss,a five-level topology and modulation strategy of ANPC mixed by SiC MOSFET and Si IGBT device is proposed.Through the carrier phase-shifting(PS-PWM)modulation strategy,all high-frequency switching actions are undertaken by SiC devices,which effectively reduces the switching loss of the system and improves the efficiency and power density of the system.The advantages of high efficiency and low loss of SiC/Si hybrid ANPC five-level inverter are verified through the comparative analysis of device losses in three types of ANPC five-level topologies by using the professional software PLECS.2.The mathematical model of SiC/Si hybrid ANPC five-level topology,specific conduction path and switching state are analyzed in detail.Based on the five-level SVM algorithm in 600 coordinate system,the method of optimizing position judgment and action time calculation in SVM is proposed,which can effectively reduce the calculation amount and bring down the complexity of system control.3.For SiC/Si hybrid ANPC five level topology and its capacitor voltage balance,analyzed the coupling mechanism of flying capacitor and neutral voltage.Based on the SVM algorithm,analyzed the influence of the voltage vector on the neutral voltage.According to the different operating conditions,select optimal vector,design seven segment and five segment of vector sequence,can quickly adjust the neutral voltage offset.Neutral voltage offset is verified by simulation the effectiveness of the proposed control strategy.