Nowadays, after new power semiconductor devices enter the field of power electronics, AC frequency conversion speed regulation, inverter devices, switching power supplies, etc. are becoming more and more popular. The original current and voltage detection components are no longer suitable for the detection of current waveforms at medium and high frequencies. In order to automatically detect and display current, and have automatic protection and more advanced intelligent control when overcurrent, overvoltage and other hazardous situations occur, it is necessary to use Hall current sensors with high speed, high precision detection, sampling and protection. The Hall current sensor module is a new generation of industrial power sensor that measures control current and voltage developed in the past ten years. 1. The basic working principle and structure of the inverter The frequency converter mentioned in this article refers to a common general frequency converter suitable for industrial general motors and frequency conversion motors. This type of frequency converter has become the mainstream of the frequency converter due to the widespread use in the industrial field. Generally, there is a slip relationship between the asynchronous motor speed and the synchronous speed. The speed regulation method can change the motor stator frequency f, the motor stator winding pole pair P, and the slip rate S to achieve any one of the best methods for asynchronous motors. It is to change the frequency f to realize speed regulation control. As long as the slip rate is not too large, it can be approximated that the speed n is proportional to f, which means that the power frequency can be continuously and smoothly changed, and a wide range of continuous smooth speed regulation of the AC motor can be achieved. From the above analysis, it can be seen that when the general-purpose inverter adjusts the speed of the asynchronous motor, the output frequency and voltage change according to certain rules. Below the rated frequency, the output current of the inverter does not change, and the output voltage increases with the increase of the output frequency, that is The so-called transformer frequency conversion (VVVF). Above the rated frequency, the voltage does not change, and the change in frequency is proportional to the output current. With the increasing use of frequency converters, the protection of frequency converters is becoming more and more important. Inverters generally have overcurrent, overvoltage, overload, and lack of equal protection. They are mainly sampled by sensors with different functions to different analog values, converted into signals suitable for single-chip microcomputers through conversion circuits, and various protections are completed by single-chip microcomputers. Among them, the role of the current sensor in the inverter is the most important, through which the current of the current inverter can be accurately measured, and it is very important for the overcurrent and overload protection of the inverter. 2. Application of Hall current sensor in frequency converter A magnetic field is induced around the wire through which current flows, and then the Hall device is used to detect the magnetic field induced by the current, and the magnitude of the current that generates this magnetic field can be measured. Thus, Hall current and voltage sensors can be constructed. Because the output voltage of the Hall device is proportional to the product of the magnetic induction applied to it and the working current flowing through it, it is a device with a multiplier function and can be directly interfaced with various logic circuits and can also be directly driven. Loads of various nature. Because the application principle of the Hall device is simple, the signal processing is convenient, and the device itself has a series of unique advantages, it also plays a very important role in the inverter. In the frequency converter, the main function of the Hall current sensor is to protect expensive high-power transistors. Because the response time of the Hall current sensor is shorter than 1μs, therefore, when an overload short circuit occurs, the power can be cut off before the transistor reaches the limit temperature, so that the transistor is reliably protected. Hall current sensors can be divided into direct measurement and zero-magnetism formulas according to their working modes. In the frequency converter, because of the need for precise control and calculation, the zero-flux method is selected. Amplify the output voltage of the Hall device, and then amplify the current, and then let this current pass through the compensation coil, and make the magnetic field generated by the compensation coil and the magnetic field generated by the measured current in the opposite direction. The magnetic flux in is 0, then the following formula holds: Io = Is (N2 / N1) In the formula, I1 is the measured current, that is, the current in the primary winding in the magnetic core, N1 is the number of turns in the primary winding, I2 is the current in the compensation winding, and N2 is the number of turns in the compensation winding. It can be seen from the above formula that when the magnetic balance is reached, Io can be obtained from Is and the turns ratio N2 / N1. The hall current sensor is characterized by the potential-free detection of current. That is, the measurement circuit can realize current detection without accessing the circuit under test, and they are coupled by the magnetic field. Therefore, the input and output circuits of the detection circuit are completely electrically isolated. During the detection process, the detection circuit and the circuit under test are not good at each other. Vacuum Cleaner With Mop,Vacuum Cleaner,Steam Cleaner,Appliances Mopping Cleaner Robot NingBo CaiNiao Intelligent Technology Co., LTD , https://www.intelligentnewbot.com