Straight-through SVPWM modulation control method based on active quasi-Z-source inverter

Abstract

The invention relates to a straight-through SVPWM modulation control method based on an active quasi-Z-source inverter. According to the method, a single adjustment period of an active quasi-Z-sourceinverter comprises four straight-through vectors with equal time lengths and 000, 100 and 110 vectors which are symmetrically arranged relative to the middle portion of the adjustment period, whereinthe middle section of the adjustment period is a 111 vector, the straight-through vectors are located at the alternating part of the zero vector and the non-zero vector, the conduction pulse of a switching device in an impedance network where the active quasi-Z-source inverter is located is arranged between the adjacent straight-through vectors, the conduction pulse is provided with a corresponding conduction coefficient, and the width of the conduction pulse is calculated according to the conduction coefficient. Compared with the prior art, the method of the invention has the advantages of small shoot-through duty ratio, high voltage gain, reduced switching frequency of the impedance network and the like.

Description

technical field [0001] The invention relates to the field of pulse width modulation of Z-source inverters, in particular to a direct-through SVPWM modulation control method based on active quasi-Z-source inverters. Background technique [0002] Due to the appearance of the Z-source network, the Z-source inverter can realize the simultaneous conduction of two switching devices on the same inverter bridge, that is, the direct-through state. The pulse width modulation technique applied to the Z-source inverter is to add the shoot-through time to the traditional pulse width modulation (PWM) modulation. Among them, the space vector pulse width modulation (SVPWM) modulation method is widely used, especially the segmental modulation method is the most common, that is, the through vector is inserted at the moment when the zero vector and the non-zero vector change each other. Segmented modulation mainly includes two-segment, four-segment and six-segment insertion methods. In terms...

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Problems solved by technology

[0004] However, with the continuous improvement of the Z-source topology, a structure with active switching devices in the impedance network has emerged. Aiming at the control of the trigger pulse of the switching device, a medium-power Z-source inverter is disclosed in the prior art. The method and system for obtaining the conduction current of the switching device, the pulse control is synchronized with the through time, and its duty cycle is equal to the through duty cycle, that is, the control signal of the active switch changes synchronously with the through state, but this can only be achieved by changing the through duty Ratio, to increase the output voltage gain, resulting in limited modulation range and limited output gain

Moreover, it is modulated according to the SVPWM four-stage method, the switching device is switched 4 times per cycle, the switching frequency is high, and the switching loss is large

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