一种漏电流检测快速保护方法研究

Study on Leakage Current Detection and Fast Protection Method

本文针对与电网连接的非隔离电力电子装置安全运行要求,提出了一种基于振荡电路和微分电路的漏电流检测和保护方法。这种漏电流保护电路由互感器、自激振荡器、二阶有源低通滤波电路和微分检测电路及系统中现有的控制芯片组成。将漏电流检测电路检测到的漏电流信号通过设备中的数字控制芯片采样,采样得到的漏电流值与安全标准中规定值进行比较,从而可形成分级保护,而对于过大的漏电流,则通过所研究的漏电流检测电路中的微分电路与软件实现快速的保护。最后通过应用于电机驱动器前端的三相双向PWM整流器中的实验验证了这种漏电流检测和保护方法的有效性。

In this paper,a leakage currentdetection and protection method based on oscillating circuit and differentialcircuit is proposed for the safety requirements of non-isolated powerelectronic devices connected to power grid.The leakage current protectioncircuit consists of transformer,self-excited oscillator,second-order activelow-pass filter circuit,differential detection circuit and existing controlchips in the system.The leakage current signal detected by the leakage currentdetection circuit is sampled through the digital control chip in the device,and the leakage current value sampled is compared with the specified value inthe safety standard,thus forming a hierarchical protection.For the excessiveleakage current,the differential circuit and software in the leakage currentdetection circuit studied can achieve rapid protection.Finally,the validityof this leakage current detection and protection method is verified byexperiments in three-phase bidirectional PWM rectifier applied to the front endof motor driver.