摘 要：某插电混动客车在运行约49000 km后出现主发电机异常烧损故障。本文通过故障拆解、理论分析与试验测试，诊断出根本原因并制定对应的解决方案。故障件分析表明，烧损集中于定子绕组与整流桥。通过对连接可靠性、短路可能性及负载分配的逐项排查，确认故障根本原因为整车供电系统中DC/DC转换器输出电压设定偏低，导致负载功率分配严重失衡，主发电机长期处于高负荷运行状态。基于此，提出将DC/DC输出电压提升至27.4V的优化方案。实测结果表明，该方案可使主发电机稳态工作电流下降40%以上，确保其在极限工况下仍低于额定供电能力，有效消除了烧损风险。
关键词：插电混动客车；主发电机；烧损故障；负载分配；DC/DC转换器；系统优化
中图分类号：U469.7；U472.4 文献标志码：A DOI：10.15917/j.cnki.1006-3331.2026.03.008
Analysis of Abnormal Burnout Fault of the Main Generator and System Optimization for Plug-in Hybrid Electric Buses
CAI Jingcheng,XUE Wenjia,REN Tianliang,LOU Zhijun,XU Jiajun,ZHANG Jiayu,WANG Chen,WANG Haibo
Abstract: A plug-in hybrid electric bus exhibits abnormal burnout failure of the main generator after operating approximately 49000 km.This paper diagnoses the root cause and develops corresponding solutions through fault disassembly,theoretical analysis,and experimental testing.Fault component analysis reveals that the burning primarily occurs on the stator winding and the rectifier bridge.By systematically checking the connection reliability,short circuit possibility,and load distribution,the paper identifies the root cause as the DC/DC converter's output voltage setting being too low in the vehicle's power supply system,which causes a serious imbalance in load power distribution and keeps the main generator in a high-load state fora long period.Based on this,the paper proposes an optimization plan to raise the DC/DC output voltage to 27.4 V.Test results demonstrate that this plan reduces the main generator’s steady-state operating current by over 40%,ensuring it remains below the rated supply capacity even under extreme conditions,thus effectively eliminating the burning risk.
Key words: plug-in hybrid bus; main generator; burnout fault; load distribution; DC/DC converter; system optimization
