Three-level anpc inverter, control method and photovoltaic system

By outputting a zero level and turning off all switching transistors in the three-level ANPC inverter, the safety hazards during zero-crossing switching or wave blocking are resolved, ensuring stable voltage of the absorption capacitor, protecting equipment safety, and improving system reliability.

CN115149833BActive Publication Date: 2025-11-07SUNGROW POWER SUPPLY CO LTD
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Patent Information

Application Number
CN202210886972.X
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2022-07-26
Publication Date
2025-11-07
Estimated Expiration
2042-07-26

AI Technical Summary

Technical Problem

In three-level ANPC inverters, the circulating current loop of the switching transistor is relatively long during zero-crossing switching or wave blocking, which leads to safety hazards, including oscillations during the charging and discharging of the absorption capacitor, excessive stress on the switching transistor, and reduced reliability.

Method used

In a three-level ANPC inverter, the controller controls the output to zero level during zero-crossing switching or wave blocking, and turns off all switching transistors to cut off the discharge path of the absorption capacitor, ensuring that the voltage of the absorption capacitor is maintained at half bus voltage and preventing charging and discharging.

Benefits of technology

It effectively prevents the absorption capacitor from discharging to zero during zero-crossing switching or wave blocking, protects the safety of the absorption capacitor and the switching transistor, avoids voltage oscillation and excessive stress, and improves system reliability.

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Abstract

The application discloses a three-level ANPC inverter, a control method and a photovoltaic system. The inverter comprises an absorption capacitor, four bridge arm switching tubes, two clamping tubes and a controller. The four bridge arm switching tubes comprise a first switching tube, a second switching tube, a third switching tube and a fourth switching tube connected in series. The common end of the first switching tube and the second switching tube is connected in parallel with the common end of the third switching tube and the fourth switching tube, and the absorption capacitor is connected between the common end of the first switching tube and the second switching tube and the common end of the third switching tube and the fourth switching tube. The two clamping tubes are connected in series and then connected in parallel across the absorption capacitor, and the common end of the two clamping tubes is used for connecting a neutral point. When the three-level ANPC inverter performs zero-crossing switching or clamping, the controller controls the three-level ANPC inverter to output zero level, controls all switching tubes of the three-level ANPC inverter to be turned off, and cuts off the discharge path of the absorption capacitor. The absorption capacitor is prevented from discharging to zero and the voltage is maintained at half of the DC bus voltage when the zero-crossing switching or clamping is performed, and the safety of the absorption capacitor and the switching tube is protected.
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Citation Information

Patent Citations

  • Flying capacitor NPC three-level topology

    CN110474550A