Design And Experiment Of Closed Loop Hall Effect Current Sensor

Closed loop Hall effect current sensor has developed rapidly development in recent years.It has been widely used in various fields including the automotive electronics, the industrialcontrol, servo motors, UPS power, military and so on. Rather than the traditional shunt andtransformer, the closed loop Hall effect current sensor with better performance, higherreliability and lower cost has been leading the research topics. The traditional design ofclosed loop Hall effect current sensor has some disadvantages, such as low reliability, lowlife, difficult manufacturing and high cost of the small-scale production. In this study, aclosed loop Hall effect current sensor based on the zero flux principle is designed,developed and analyzed. Due to the improvement of material, device and process, theoptimized closed loop Hall effect current sensor in our study shows significant advantagesover conventional one.The closed loop Hall effect current sensor is optimized by combining simulations andexperiments. The influences of gap width, Hall element size, secondary coil and defects inPCB bonding on the sensitivity, linearity and accuracy of the closed loop Hall currentsensor were analyzed. The gap width had a major influence on the sensitivity and accuracyof the sensor. When the gap width is1.1mm, the magnetic induction intensity is the biggestwhile the leakage is smallest. Consequently, the sensor with a gap width of1.1mm showeda greatest sensitivity. The choosing of Hall element had a great effect on the sensitivity andlinearity. The use of HW302B could introduce significant improvement in the sensorperformance due to its high sensitivity and high spatial resolution. The secondary coil usedthe0.831.5mm pancake enameled wire, which was helpful to accelerate the windingprocess and improve the accuracy. Base on the aforementioned analysis, the closed loopHall current sensor is optimized and improved. The experimental results of the optimizedand improved sensors agreed well with the theoretical analysis.Simulations were conducted to analyze the effect of air gap width variation of iron coreon the magnetic induction. The simulation results showed the magnetic induction wassignificantly reduced when the air gap width increased. Smaller magnetic induction leads toweaker detected information of Hall element. When the detected information wasweakened, the compensated current becomes smaller. So, a wider air gap width led to lower accuracy of the current sensor. We also simulated the impact of secondary coil area onmagnetic induction based on Max-Well theory. We found that magnetic induction wasreduced when the secondary coil area increased. This led to an increased remanentmagnetization in an iron core.To further improve the Hall effect current sensor, the amplification circuit, feedbackcircuit and temperature compensation circuit were studied. The defects occurred in thewelding of the sensor with the printed circuit board in the engineering application wasanalyzed and a defect detection method was put forward.