摘要
随着PWM变频器在电机控制中的广泛应用,在电机控制性能显著提高的同时,系统共模电流(正常漏电流)的问题愈发严重。同时,当电机系统发生漏电故障时,现有漏电保护装置不能区分故障漏电流和正常漏电流,导致系统存在安全隐患。针对此问题,首先对PWM电机系统正常漏电流计算模型和流通路径进行研究,然后对系统的漏电故障点及相应故障漏电流进行了分析,最后通过试验测试对PWM电机系统正常漏电流和正常与故障混合漏电流的时频特性进行深入分析和研究,为正常漏电流的有效抑制和故障漏电流的准确检测提供理论指导。
With the wide application of PWM converter in motor control,the motor control performance is significantly improved,but the problems caused by common-mode current(normal leakage current) are becoming more and more serious.In addition,when leakage fault occurs in motor system,the conventional leakage fault protection devices cannot distinguish between fault leakage current and normal leakage current,which leads to a security risk in the system.In order to solve these problems,this paper firstly studies the calculation model and flow path of normal leakage current in PWM motor system.Then the leakage fault point and the corresponding fault leakage current of motor system are analyzed.Finally,the time/frequency domain characteristics of the normal leakage current as well as the normal and fault mixed leakage current in PWM motor system are analyzed through experimental testing.The conclusions provide theoretical guidance for the effective suppression of normal leakage current and the accurate detection of fault leakage current.
引文
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