Capacitor Voltage Balancing Control Strategy For Five-level ANPC Inverter

The optimization of multilevel inverter technology has been paid more attention to because of its wide application in the field of power electronics.Reducing the DC ripple,minimizing the output THD,controlling the capacitor voltage,balancing and reducing the device loss are the main objectives of the multilevel field.Based on the five-level ANPC inverter,this paper realizes the control effect of inverter capacitor voltage balance by improving the switch sequence and vector.The main work of this paper includes the following points:(1)The topology and modulation technology of multilevel inverter are discussed,and the advantages and disadvantages of universal topology and modulation technology are summarized.(2)The simulation platform of the five-level ANPC inverter is set up,and the experimental platform is briefly introduced.(3)The mathematical model and working principle of the five-level ANPC inverter are introduced,and the influence of the eight different conduction modes on the flying capacitor voltage and the neutral potential(NP)is analyzed.An improved space vector pulse width modulation(SVPWM)method is proposed to solve the problem of capacitor voltage offset in the five-level ANPC inverter.Using the redundancy of the output path and the central symmetry of the switch sequence,the capacitor voltage balance is realized.(4)In order to realize the coordinated control of the balance between the flying capacitor voltage and the NP,a five-level virtual space vector modulation(VSVM)stategy is proposed.A new space vector partition is formed by virtual synthesis of partial vectors to realize the capacitive voltage balance control of the five-level ANPC inverter.