FPGA Implementation Method for Human Body Electric Shock Protection Based on Human Body Impedance Model

Human body electric shock protection is related to the life safety of the people and is an important topic in low-voltage distribution network. According to the characteristic difference between the real part and imaginary part of the model of human body impedance by IEC, a human body electric shock protection principle based on the real part of residual current variation impedance is constructed to protect against human body electric shock by sampling the residual current and three-phase voltage. Based on Field Programmable Gate Array (FPGA), a fully digital hardware design scheme for human body electric shock protection is proposed, including high-speed sampling, Discrete Fourier Transform, and fault sudden-change starting, fault phase selection, impedance calculation and discrimination. The experimental results show that the application-specific integrated circuit (ASIC) designed in this paper provides human body electric shock protection at a sampling rate of 5kHz, and behaves well in terms of the speed and effectiveness of the protection.