Dual space vector modulation method for three-level direct matrix converter

Abstract

The invention relates to a dual space vector modulation method for a three-level direct matrix converter, comprising the following steps of: 1, enabling the three-level direct matrix converter to be equivalent to a series circuit model of a virtual rectifier stage and a virtual inverter stage; 2, determining an output phase current space vector and an input phase voltage space vector to obtain a desired input phase current space vector and a desired output phase voltage space vector; 3, performing SVPWAM modulation on the virtual rectifier stage to obtain the duty ratio of a corresponding effective vector; 4, performing VSVPWM modulation on the virtual inverter stage to obtain the duty ratio of the corresponding effective vector; and 5, combining the virtual rectifier stage and the virtualinverter stage to obtain the switch matrix of the three-level direct matrix converter, and then obtaining the switching signals of respective bidirectional switches of the three-level direct matrix converter so as to realize modulation. Compared with the prior art, the method has the advantages of improving output performance, reducing switching frequency, reducing switching loss, and improving input and output waveform quality.

Description

technical field [0001] The invention relates to a control method for a three-level direct matrix converter, in particular to a dual space vector modulation method for a three-level direct matrix converter. Background technique [0002] In the field of AC power conversion, the research and utilization of AC-DC-AC converters have made great progress, but there are still many shortcomings, especially the intermediate DC link requires large-capacity inductors or capacitors, which increases the size of the device and installation. The cost reduces the performance of the converter; the input side adopts a full-bridge rectification method, which reduces the power factor of the grid and brings large harmonic pollution to the grid. Although the traditional AC-AC converter has high commutation efficiency, it also has many disadvantages, such as using more thyristors and complicated wiring; using phase-controlled rectification, the power factor is low; the output frequency range is nar...

AI Technical Summary

Problems solved by technology

There are few modulation methods based on three-level direct matrix converters in the prior art, and the applicable three-level direct matrix converter control methods can achieve basic control, but in the control process, different switching states The corresponding space vectors produce different midpoint currents. The average value of the midpoint current generated by the traditional recent three-vector method in each PWM cycle is not zero, which makes the midpoint potential shift and low-frequency oscillation occurs, resulting in poor output performance. Stablize

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