Several ways of current sampling

QWE4562009

Several ways of current sampling [Copy link]

Several ways of current sampling

1. Use sampling resistors directly and ADC to measure the voltage drop on the resistor without processing circuits such as op amps
. 2. Use sampling resistors and ADC to measure the voltage drop on the resistor, and then process it through op amps and other processing circuits, such as differential amplifiers, followers, etc.
3. The transformers used in power equipment such as electric meters and smart circuit breakers collect the AC voltage and then send it to the ADC port of the MCU for sampling after precise rectification (shaping transformation) by the op amp.
4. Use Hall sensors. This method has never been used before. Do I need a coil transformer? If you know, please share the relevant circuits.
5. There may be other sensors, but they have not been applied in large quantities yet.


Use Hall sensors. This method has never been used before. Do I need a coil transformer? If you know, please share the relevant circuits.

lugl4313820

I have always wanted to learn about the sampling circuit of the sampling resistor. I wonder if you have time to teach me.

bigbat

Hall sensors are all finished products and have never been disassembled. They are similar to mutual inductors.

Gen_X

The Hall sensor currently used to measure large currents is made into the shape of a building based on the traditional transformer.

In fact, most Hall sensors have integrated buffered operational amplifiers, which are convenient for direct use. The detection end can directly accept 0-200A (0-5A is more commonly used). There are AC and DC, and the output is a voltage signal, which can be directly connected to most circuits.

EricCheng

I would like to ask how to design the common-mode filter in front of the op amp?

zmldty

Take a look and learn a little. . . . . . . . . . . . . . . . . . . . . .

QWE4562009

bigbat posted on 2022-6-17 09:21 Hall sensors are all finished products and have never been disassembled. It is similar to mutual inductors

It is so big that it is not suitable for portable products! Is the output of this sensor directly given to the MCU?

QWE4562009

Gen_X posted on 2022-6-17 10:00 The Hall sensor currently used to measure large currents is made into the shape of the building on the basis of the traditional mutual inductor. In fact, most Hall sensors integrate buffers...

A moderator was talking about the SO8 packaged Hall sensor. He was not talking about the Hall sensor.

bigbat

QWE4562009 posted on 2022-6-21 15:40 It is so big that it is not suitable for use in portable products! Does the output of this sensor go directly to the MCU?

No! The circuit needs to be conditioned

bigbat

QWE4562009 posted on 2022-6-21 15:42 A moderator is talking about the SO8 packaged Hall sensor. He is not talking about the Hall sensor

This cannot be used in current detection, which is usually a magnetic induction switch. Inconsistent packaging of magnetic components is likely to cause measurement failure.