Three-phase four-wire three-level inverter universal 3D-SVPWM control method and control system under imbalance load

Abstract

The invention discloses a three-phase four-wire three-level inverter universal 3D-SVPWM control method and control system under an imbalance load. According to the method, a three-phase output voltagestate combination is obtained according to the switching states of bridge arms of a three-level inverter; the three-phase output voltage is converted into an alpha-beta-o coordinate system by means of equal-amplitude transformation; a new coordinate origin and a corresponding zero-axis vector at the origin are defined; a three-dimensional subspace after coordinate translation is projected to alpha-beta plane, and vector synthesis is carried out by combining the zero-axis vector; and a vector type is decomposed, and zero sequence components generated by asymmetric loads are compensated by adjusting the action time of the zero-axis vector, thereby maintaining the balance of voltage output. According to the method, the redundant small vectors do not need to be considered in the space division process for additional division of the inner and outer subspaces, so that the space sector division algorithm is simplified; and meanwhile, the projection of the three-dimensional subspace in the alpha-beta plane is combined with the zero axis vector, so that complex vector selection and calculation can be avoided, and high universality is achieved.

Description

technical field [0001] The invention relates to the control technology in the field of power electronic conversion devices, in particular to a general-purpose 3D-SVPWM control method and control system for three-phase four-wire three-level inverters under unbalanced loads. Background technique [0002] With the development of power electronics technology, the application of two-level inverters in low-power active filtering and motor speed control systems has become quite mature. In the industrial field, two-level inverters can no longer meet the actual needs, and multi-level inverters represented by three-level inverters have emerged as the times require. Compared with the two-level inverter, the three-level inverter has the advantages of low output waveform distortion rate, small device voltage stress and low system electromagnetic interference, so it is widely used in power grid active filtering, motor frequency control and power system wireless Compensation and other fie...

AI Technical Summary

Problems solved by technology

In addition, in the existing SVPWM control method, the four-leg three-level inverter often performs vector control as a whole, and the complexity of the algorithm is increased. The method cannot be used universally, increasing the repeatability of research analysis

Images