Modulation method for improving current stress of quasi-Z-source inverter switching device

Abstract

The invention provides a modulation method for improving the current stress of a quasi-Z-source inverter switching device, and the modulation method comprises the steps: subtracting the maximum valueof saddle waves from saddle waves of a conventional voltage space vector modulation SVPWM with the phase difference of 120 degrees to obtain three modulating waves, wherein the maximum value of three-phase saddle waves is a straight line according to the converted waveform, and translating the straight line upwards for M / 2, wherein M is the distance between the maximum value and the minimum valueof the modulated wave after the modulated wave and the triangular carrier wave are subjected to per-unit processing between 0 and 1. According to the modulation method, the gate-level signal generation process is simple, the switching loss is low, no low-frequency alternating-current component exists on the input direct-current side, the current stress of the switching device is greatly reduced, and the service life of the switching device is prolonged.

Description

technical field [0001] The invention belongs to the field of inverter control, and more specifically relates to a modulation method for improving the current stress of a switch device of a quasi-Z source inverter. Background technique [0002] With the increasingly prominent environmental problems, countries are vigorously developing new energy industries. The mainstream inverter topology in the field of new energy is the voltage source inverter (Voltage source inverter, VSI), which is evolved from a buck converter and can only work in buck mode. In order to meet the wide-range voltage input of the rear inverter, the new energy power generation system usually adopts the structure of DC-DC conversion circuit + inverter. This kind of multi-level converter has large energy loss, and has limitations in terms of conversion efficiency, reliability and cost. On the other hand, the upper and lower switching tubes of the same VSI bridge arm cannot be turned on at the same time, oth...

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Problems solved by technology

[0011] (1) The number of commutation times of the switching device is large, which leads to an increase in the switching loss of the device;

[0012] (2) The traditional SVPWM modulation strategy needs to use 5 reference signals, which makes the generation process of the gate-level signal that controls the device to be turned on or off more complicated;

[0013] (3) The continuous commutation of switching devices in the fundamental frequency period will lead to a large current stress on the switching devices of some quasi-Z source inverters using traditional modulation strategies

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