A control method for a three-phase-two-phase matrix converter

Abstract

The invention discloses a three phase-two phase matrix converter and a control method, which relate to the technical field of AC converters. The three phase-two phase matrix converter comprises four two-way switch groups, a compensation inductor and a controller, wherein the four two-way switch groups are used for converting three-phase AC input to two-phase AC output, the input ends of the four two-way switch groups are connected with three-phase input respectively, the output ends of two two-way switch groups are used as two-phase output ends, and the output ends of the other two two-way switch groups are used as a compensation end and a common end respectively; one end of the compensation inductor is connected with the compensation end and the other end is connected with the common end;and the controller is used for controlling the two-way switches in the two-way switch groups to be on and off according to a preset rule. Through reasonably setting the relative relationship betweena modulation function coefficient of the output end and a modulation function coefficient of the compensation end, the pulsating power generated by the two phase asymmetry of the output can be suppressed from being coupled to an input side through the two-way switches, and influences on input current quality are reduced.

Description

technical field [0001] The invention relates to the technical field of alternating current conversion devices, in particular to a control method for a three-phase-two-phase matrix converter. Background technique [0002] like figure 1 It is a conventional three-phase-two-phase matrix converter with three-terminal output with an independent neutral line, and its input three-phase symmetrical voltage e abc The expression is: [0003] [0004] In the above formula, E i is the magnitude of the input three-phase voltage. [0005] Assuming that the two-phase output voltages are in quadrature, the two-phase voltage expression on the output side is: [0006] [0007] In the formula, U 1 , U 2 are the amplitudes of the output two-phase fundamental wave voltages respectively, and the output asymmetry is defined as ε=U 2 / U 1 , and U 1 ≥U 2 ; o is the output angular frequency. [0008] In order to simplify the derivation process, the phase difference δ between the cur...

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Problems solved by technology

[0021] It can be seen from formula (7) that the conventional three-phase-two-phase matrix converter with three-terminal output with an independent neutral line and the conventional control algorithm can only achieve two-phase asymmetric sinusoidal output, which cannot guarantee the input performance, that is, the input contains difficult Elimination of low-frequency harmonics, and the input low-frequency harmonic content η 1 , η 2 And the THD value of the input current is related to the output asymmetry ε

[0022] In the prior art, an improved phase angle modulation method is used to reduce the 3-2MC input current harmonics caused by the asymmetry of the output two phases, but this method is limited to the case where the input and output are at the same frequency, such as the output and input frequencies are not equal, or require If the output frequency is continuously adjustable, there will be a large amount of harmonics in the input current, and the harmonic frequency is low, so it is not easy to filter out with an input LC filter

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