A point balance and circulation suppression control method, device, equipment and medium

By acquiring the three-phase current and positive and negative DC bus voltages of the parallel converter, and using closed-loop control of the dq-axis and o-axis currents to calculate the compensation voltage and limit the difference, the voltage balance at the midpoint of the three-level converter and the suppression of circulating current are achieved. This solves the problems of DC bus voltage imbalance and circulating current, and improves the stability and reliability of the system.

CN122159710APending Publication Date: 2026-06-05东方电气风电股份有限公司
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
东方电气风电股份有限公司
Filing Date
2026-03-17
Publication Date
2026-06-05

AI Technical Summary

Technical Problem

In parallel applications of three-level converters, there are issues such as reduced AC power quality due to DC bus voltage imbalance, converter overvoltage/overcurrent faults and failure of key components, as well as module processing imbalance and local overload problems caused by parallel circulating current.

Method used

By acquiring the three-phase current and positive and negative DC bus voltages of the parallel converter, and based on dq-axis current closed-loop control and o-axis current closed-loop control, the compensation control voltage is calculated and the difference is limited to achieve voltage balance at the midpoint of the three-level converter and suppression of circulating current. Pulse width modulation technology is used for control.

Benefits of technology

It effectively solves the overcurrent and overvoltage problems caused by circulating current and neutral point voltage imbalance in parallel three-level converters, and improves the stability and reliability of the system.

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Abstract

The application discloses a point balance and circulating current suppression control method, device, equipment and medium, and relates to the technical field of power electronic control. The application is applied to a first three-level converter and a second three-level converter in parallel. Three-phase currents and a DC bus voltage are collected in real time, dq-axis current closed-loop control is performed, and o-axis current closed-loop control is performed on the second three-level converter. Based on a given voltage in a three-phase stationary coordinate system, midpoint voltage balance control operation is performed, and a compensation control voltage is calculated. The compensation voltage is limited by a difference limiting strategy, is superimposed into the given control voltage, and finally control signals are generated through pulse width modulation. Through the active injection of o-axis control components and the optimized difference limiting midpoint balance algorithm, the application effectively solves the circulating current problem and the midpoint potential imbalance problem in the parallel system, and improves the reliability of the system.
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