Circuit Design of Leakage Detection Instrumentation of NEC Microcontroller

Single chip microcomputer STM32L151CCU6

Overview:
With the widespread use of electronic instruments and electronic devices, especially the popularity of household appliances, the safety of household appliances cannot be ignored. Leakage current, insulation resistance, and electrical strength are called the three major electrical parameters in electrical safety performance. The leakage current, especially the leakage current at the working temperature, is a safe electrical parameter that most accurately reflects the actual working state; it is also an electrical parameter that has a direct impact on human safety. Because, when one end of the power cord is grounded and the human body touches the outer casing of the electric appliance, the leakage current of the electric appliance will flow through the human body and may cause personal injury or death. Therefore, leakage detection is of great significance to both household appliances and people's own safety. Through the detection of leakage, specific reactions can be made according to the leakage situation, thus protecting the safety of circuits and personal property.

There are many methods for detecting leakage current in power system loops, such as insulation monitoring devices, low-frequency detection methods, frequency conversion detection methods, and Hall magnetic balance. This design adopts the Hall magnetic balance principle. In order to overcome the influence of the residual magnetism of the sensor on the leakage current detected by the system, the zero point is designed as a system that can be adjusted by the button.
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