Grid-connected inverter zero crossing point current distortion suppression method of unipolar critical current continuous control strategy

Abstract

According to a single-phase unipolar grid-connected inverter, a control strategy of a unipolar critical current continuous mode is adopted to realize zero voltage turn-on of a switch tube in order to reduce switch loss. Since the voltage value at a voltage zero crossing part of a power grid is extremely small, the expected critical current continuous control strategy cannot be realized, and the problem of current oscillation on the voltage zero crossing part of the power grid is caused. The invention provides the unipolar critical current control strategy in which gradual change is adopted at the zero crossing part of the power grid, so the problem of zero crossing point oscillation of grid-connected current is solved. The improved unipolar critical current continuous control strategy is suitable for the grid-connected inverter application occasions with smaller power and higher switch frequency.

Description

technical field [0001] The invention relates to a zero-crossing current distortion suppression method of a grid-connected inverter with a unipolar critical current continuous control strategy, and belongs to the technical field of power electronic converters. Background technique [0002] Grid-connected inverters are widely used in new energy power generation and power conversion. Improving the switching frequency of the inverter and reducing the volume and cost of the inverter are a pursuit goal of the grid-connected inverter design. Increasing the switching frequency can reduce the volume of passive components, which in turn can increase the power density of the grid-connected inverter. However, increasing the switching frequency will not only increase the switching loss, but also bring greater electromagnetic interference. [0003] The application of soft switching technology will greatly reduce the switching loss, effectively increase the switching frequency, reduce th...

AI Technical Summary

Problems solved by technology

[0009] Aiming at the serious problem of current distortion at the zero-crossing point of the existing unipolar critical current continuous grid-connected inverter, the present invention proposes a method for suppressing the zero-crossing current distortion by adopting a control strategy of gradual change of the critical current value near the zero-crossing of the grid voltage

[0011] A unipolar critical current continuous control strategy that adopts a gradual change of the critical current value near zero-crossing of the grid voltage solves the problem of zero-crossing current oscillation

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