Threephase output balance control of the high leakage inductance transformer based on the PWM modulation

WANG Zeze1, LI Wenwei2, ZHANG Shengmeng3, YANG Lin3, JIN Lijun1

（1.School of electronics and information engineering, Tongji University, Shanghai 201804, China；
2.Guangxi power grid Qinzhou Power Supply Bureau，Qinzhou Guangxi 535009, China;
3.Zhejiang Guan Hua Electric Co., Ltd., Yueqing 325606, China）

Abstract: To solve the problem of the imbalanced threephase output voltage of the high leakage inductance transformer, the inverter output transformer of the electric locomotive auxiliary power supply was researched, which was integrated with reactors for the power locomotives. By voltage closedloop and PWM modulation, balancing threephase output voltage and improving the quality of the transformers power supply was achieved. Setting up the high leakage inductance transformer and the filter inductor integrated model, the leakage inductance of the transformer was calculated through energy method, matching the inductance parameters of the lowpass filter. The transformers high leakage inductance calculation was conducted based on the Simulink simulation in the unstable threephase load, getting the threephase output voltage under the condition of unbalanced waveform problem. The voltage closedloop circuit was established to control the output voltage waveform through the PWM switch signal modulation of the inverter input. The results show that the error of transformer leakage inductance calculation by energy method is within 10% of measured values. Based on the PWM modulation output voltage closedloop control, the threephase output voltage imbalance can be effectively suppressed, improving the quality of transformers power supply.

Key words: high leakage inductance transformer; leakage inductance calculation; working condition simulation; output unbalance control