Control method for realizing full-range soft switching of four-quadrant operation of three-phase inverter

Abstract

The invention relates to a control method for realizing full-range soft switching of four-quadrant operation of a three-phase inverter. The control method comprises the following steps of: 1, building a converter system which comprises a three-phase inverter topology, a digital controller, a sampling circuit and a driving circuit; 2, decomposing the load phase current to obtain d-axis and q-axis components for current closed-loop control; and carrying out DPWM modulation to obtain a modulation wave; 3, sampling load phase current, load phase voltage and direct current bus voltage, and updating a carrier period in real time by a digital controller; and the driving circuit driving the corresponding switching devices to realize soft switching of all the switching devices in a full range. The critical switching frequency curve of soft switching of the switching devices under different power factors is analyzed, and the minimum critical switching frequency curve is used as the switching frequency curve of soft switching of all the switching devices, so that the problem of large switching loss when the three-phase inverter operates under different power factors is solved, and the three-phase inverter has relatively high switching frequency.

Description

technical field [0001] The invention belongs to the non-isolated high-frequency power conversion direction in the technical field of power electronics, and in particular relates to a control method for realizing full-range soft switching of a three-phase inverter with four-quadrant operation. Background technique [0002] Three-phase inverters are widely used in various industrial equipment and civil devices, such as photovoltaic systems, static var generators or AC asynchronous motors, etc. Most of these applications need to consume reactive power, so three-phase inverters are required The inverter can have the ability to generate or absorb reactive power, that is, the three-phase inverter is required to be able to work under non-unity power factor conditions. In the traditional three-phase inverter, because half of the switching devices are in the hard switching state during operation, the switching loss of the switching devices is very large, so the switching frequency of...

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Problems solved by technology

Since the zero-crossing moment of the inductor current on the three-phase inverter side is not synchronous, the switching device corresponding to the zero-crossing phase first and the switching device corresponding to the zero-crossing phase are controlled to be turned off at the same time. Although frequency synchronization can be achieved under this control method , but will cause the current to appear discontinuous

In the working condition of non-unity power factor, this document only analyzes the power factor from leading 0.8 to lagging 0.8, and the soft switching of switching devices under the full power factor range needs to be realized

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