Three-level inverter and zero-crossing switching logic control method thereof

Abstract

The invention relates to a three-level inverter and a zero-crossing switching logic control method thereof. The control method comprises the following steps of: judging an area where switching signal happens; and if the switching signal happens in a first area, a third area or a fourth area, controlling outer tubes Q1 and Q4 of four three-level switching tubes to be positioned in a closed state, maintaining the invariable state of inner tubes Q2 and Q3 before switching until PWM2 is high level, and performing control according to the primary wave logic. Due to the wave logic control, the switching process is divided into four different areas. The logic control is performed on the switching tubes Q1, Q2, Q3, and Q4 in the different areas. Due to the logic control, when the three-level inverter is in the process of positive and negative semi-cycle switching, the dead zone time between complementary switching tubes (Q1 and Q3, Q2 and Q4) is guaranteed, and the defect that the switching tube Q2 and the switching tube Q4 or the switching tube Q1 and the switching tube Q3 are connected simultaneously to make the inverter bridge arm short-circuited so as to cause abnormal work of the circuit is avoided. Therefore, the normal and stable work of the circuit is guaranteed.

Description

technical field [0001] The invention relates to the technical field of power equipment, and more specifically, relates to a three-level inverter and a zero-crossing switching logic control method thereof. Background technique [0002] In recent years, in high-voltage and high-power applications, a new type of power electronic converter --- multilevel converter has received more and more attention. The so-called multilevel converter (Multilevel Converter, MLC) has 4 or more power semiconductor devices on the bridge arm, which realizes multi-level ladder wave output through different combinations of voltage division and switching actions on the DC side Current can make the waveform closer to a sine wave. Diode-clamped three-level converter structure (single-phase) such as figure 1 As shown, it can effectively improve the withstand voltage of the converter system, reduce output voltage harmonics and switching losses, and is generally valued in high-power applications of power...

AI Technical Summary

Problems solved by technology

[0016] The technical problem to be solved by the present invention is that the dead zone between the complementary main switch tubes (Q1 and Q3, Q2 and Q4) will be reduced during the positive and negative half cycle switching process of the existing three-level inverter, Even if it is reduced to zero, it will cause a short circuit of the inverter bridge arm, thereby causing the defect that the circuit cannot work normally. A three-level inverter and its zero-crossing switching logic control method are provided.

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