Here mainly introduces the current detection method, and finds some factors that are easily overlooked in the design. First consider two different methods: magnetic field-based detection method and shunt-based detection method. 1. Magnetic field-based detection methods (represented by current transformers and Hall sensors) have many advantages, such as good isolation and low power loss, which makes it more used in Power Supply drive technology and large current fields, but It also has shortcomings, such as large volume, unsatisfactory compensation characteristics, linearity and temperature characteristics. 2. Method of shunt High-precision low-resistance resistors currently have the characteristics of high power and small size. This method has lower cost and higher accuracy. Used more in automotive electronics. To achieve the function of anti-trapping, usually two methods are used for detection at the same time. The following uses window control as an example. The working current of the body electronic control system is generally between 1-100A, but we need to pay attention that most loads have Inrush current. What needs to be involved today is the shunt method. This is the principle of our detection is this: the shunt method is to insert a low resistance detection resistor in series in the current path to form a small voltage drop, which can be amplified to be regarded as a A signal proportional to the current. Of course there are two most basic topologies: Of course there are two most basic topologies: Low-side current detection Put the detection resistor between the load and the circuit ground, then you can use the op amp to amplify the voltage drop formed on the resistor. High-side detection Place the sense resistor between the power supply and the load. If you want to subdivide more, you can consider the position of the switch together, because we are facing an inductive load. The op-amp circuit for high-end detection is shown in the following figure (both of these figures are at the principle level, and there are actually many problems that are worth thinking about): Car Mobile Charger,Car Charger,Iphone Car Charger,Portable Car Charger Ninghai Yingjiao Electrical Co., Ltd. , https://www.yingjiaoadapter.com
