Three-stage svpwm algorithm for reducing switching loss of h/npc converter

Abstract

The invention belongs to the technical field of inverter control, and in particular relates to a three-stage SVPWM algorithm for reducing switching loss of an H / NPC converter. It includes the following steps: S1, according to the multi-level SVPWM algorithm based on the 60° coordinate system, calculate the action time T1, T2, T3 corresponding to the three basic vectors V1, V2, V3; S2, select the switch state of the basic space voltage vector, According to the principle of reducing the common-mode voltage, select the switching state in the middle of the basic space voltage vector, and sort it according to the value S of the switching state from small to large; S3, according to the last switching state of the switching sequence of the previous switching cycle, determine the next For the first switching state of the switching sequence in the switching cycle, select the switching state with the smallest switching state as the initial state; S4, design a three-stage switching sequence according to the principle of the smallest switching in the switching sequence; S5, switch state mapping.

Description

technical field [0001] The invention belongs to the technical field of inverter control, and in particular relates to a three-stage SVPWM algorithm for reducing switching loss of an H / NPC converter. Background technique [0002] At present, the use of frequency conversion technology based on high-power frequency conversion devices in the fields of electric power, ships, mine hoisting, and steel rolling has become the main measure for efficient energy utilization. Common medium-high voltage high-power multilevel converter topologies can be divided into two categories: 1) Half-bridge clamp type (diode clamp type and flying capacitor type), 2) Full-bridge cascaded type, the former has DC The problem of side capacitor voltage balance, when the number of levels is greater than three, the control will become more complicated. Cascade converters include 2H bridge cascade, H / NPC cascade and hybrid cascade. The 2H bridge cascade type is easy to expand and the control method is simp...

AI Technical Summary

Problems solved by technology

The 2H bridge cascade type is easy to expand and the control method is simple, but it requires a large number of independent DC power supplies

However, for multilevel converters with more than five levels, the switching sequence design is more complicated, and the seven-segment switching sequence needs to meet strict restrictions, resulting in inflexible switching sequence design

At the same time, when the switching frequency is low, when the switching sequence of the seven-segment SVPWM algorithm is switched between adjacent small sectors, the additional switching loss is greatly increased, and the harmonics of the output voltage increase, which greatly limits the operation of the seven-segment SVPWM algorithm at high voltages. Power multi-level field, especially low switching frequency applications

Images