Comparison between open-loop Hall and closed-loop Hall sensors
How to distinguish between open-loop and closed-loop Hall current sensors? Below, Wei Kewei will compare the differences between open-loop and closed-loop Hall current sensors.
1. Working principle of open-loop Hall sensor:
The magnetic flux generated by the primary current (Ip) is concentrated in the magnetic circuit and sensed by Hall devices in the air gap for measurement. The signal output by Hall devices accurately reflects the output situation of the primary current.
Features: Small package size, wide measurement range, light weight, low power loss, no insertion loss
2. Working principle of closed-loop Hall sensor:
The compensation magnetic flux generated by the secondary current balances the magnetic flux generated by the primary current Ip. The secondary compensation current generated by Hall devices and auxiliary circuits accurately reflects the magnitude of the primary current.
Features: Wide frequency range, high accuracy, fast response, low temperature drift, good linearity, no insertion loss.
Additionally, it is also possible toBandwidth, accuracy, magnetic saturationTo distinguish between open-loop and closed-loop Hall sensors.
1) Due to different bandwidths, the magnetic field at the air gap always changes around zero flux. As the amplitude of the magnetic field change is very small, the frequency of the change can be faster. Therefore, the closed-loop Hall current sensor has a fast response time. The bandwidth of actual closed-loop Hall current sensors can usually reach over 100kHz. The bandwidth of open-loop Hall current sensors is usually narrow, around 3kHz.
2) Due to different accuracies, the secondary output of open-loop Hall current sensors is proportional to the magnetic induction intensity at the air gap of the magnetic core. The magnetic core is made of highly permeable materials, and nonlinearity and hysteresis effects are inherent characteristics of all highly permeable materials. Therefore, open-loop Hall current sensors generally have different linearity angles, and the secondary output of the primary signal will vary during the rise and fall process. The accuracy of open-loop Hall current sensors is usually inferior to 1%. The closed-loop Hall current sensor operates in a zero flux state, and the nonlinearity and hysteresis effects of the magnetic core do not affect the output, resulting in good linearity and high accuracy. The accuracy of closed-loop Hall current sensors can generally reach 0.2%.
3) Both open-loop Hall and closed-loop Hall have magnetic saturation problems. The open-loop problem is more direct. When the primary current is too high and the magnetic field strength exceeds the normal working range of the magnetization curve, magnetic saturation occurs; Closed loop Hall works under zero magnetic field, but magnetic saturation can also occur in abnormal situations. Simply put, magnetic saturation occurs when the secondary coil is not powered or the primary current is too high.
The above is Wei Kewei's summaryhall sensor The comparison between open-loop and closed-loop has been made. If you have any other opinions or suggestions regarding the open-loop and closed-loop of Hall sensors, you can directly contact Weikewei Technology customer service. Of course, if you have a need for Hall sensors, you can compare them with Hall sensors on the market. I believe that the advantages of Wekeway are significant.