Multifunctional space vector modulation method for current-source converter

Abstract

The invention discloses a multifunctional space vector modulation method for a current-source converter. The method can compensate the system reactive power while reducing the common-mode voltage of the current-source converter, and comprises steps of 1, mapping the nine switching current states of the current-source converter to nine vector states in an [alpha][beta] space coordinate system according to the clark transform; 2, calculating the common-mode voltage corresponding to each vector, and providing a method of selecting a zero vector to reduce the system common-mode voltage; 3, transforming the voltage and current of the grid-connected point of the converter into the dq coordinates, controlling the active power and the reactive power of the system by controlling the d-axis currentand the q-axis current of the converter respectively, and accordingly determining a converter modulation reference vector; and 4, determining the three switch vectors of a composite reference vector based on an ampere-second balance principle, and then determining a zero-vector corresponding switch state according to the method in step 2. The modulation method realizes active power and reactive power independent control through the dq coordinate transformation, and uses the zero vector with the lowest common-mode voltage for synthesizing the reference vector to reduce the common-mode voltage of the system.

Description

technical field [0001] The invention relates to a multifunctional current source converter space vector modulation method, in particular to a modulation method capable of simultaneously reducing the common mode voltage of the current source converter and realizing the maximum power factor operation of the converter. Background technique [0002] Converter technology is a technology that converts electrical energy from DC to AC or AC to DC, and plays an important role in today's industrial applications. Three-phase current source converters are widely used. The principle is to use switching tubes to build the main circuit, and then cooperate with the corresponding modulation method to control the switching state of the switching tubes, so that the input / output current waveform is approximately sinusoidal. The basic principle of the space vector modulation method of the current source converter is to convert the nine kinds of PWM current states of the current source type three...

AI Technical Summary

Problems solved by technology

[0003] Since the traditional space vector modulation method does not select the zero vector, the peak value of the common mode voltage of the converter is high, which is not conducive to the insulation of the system

The method of adding common-mode reactors can reduce the influence of common-mode voltage to a certain extent, but it will increase the size and cost of the system

On the other hand, due to the existence of the filter capacitor of the LC filter circuit on the AC side of the converter, the power grid node will have a leading power factor

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