0 Preface

Current detection has important applications in mechanical control, protection, detection, and power management. For example: motor drive control, frequency conversion control, battery state of charge monitoring, etc. However, there are two difficulties in current measurement: 1) the measuring instrument is not convenient to be directly connected to the circuit; 2) the current detection circuit and the circuit under test cannot be directly coupled, otherwise, it will affect the DC operating point of the circuit under test. Hall sensors are widely favored in current monitoring due to their small size, low power consumption, low noise, and good isolation. Especially the design of Hall sensor with magnetic ring has been widely used. However, due to the relatively low sensitivity of the traditional Hall sensor, the processing circuit is required to be high, and the system cost is high. If the traditional Hall sensor is used improperly, its Hall voltage UH has a nonlinear relationship with the magnetic induction intensity B, and there is an unbalanced voltage, which seriously affects the accuracy of the detection system. The Lime HO series Hall sensor based on the Hall effect greatly improves the sensitivity of current detection, and has simple processing circuit, easy installation, good linearity and high accuracy.

1 Function introduction of HO series Hall sensor

Compared with the traditional open-loop Hall sensor, the advantages of the HO open-loop Hall sensor include: good linearity, high sensitivity; programmable overcurrent detection function; short programmable response time (2 to 6us ); low zero point and gain drift; multiple range settings, which can achieve nominal current measurement from 2.67 to 25A; designers can set the HO series Hall sensor output reference voltage to 0.5, 1.5, 1.65 or 2.5 through a dedicated port V; Can be packaged in PCB.

2 Analysis of the current detection function of HO series Hall sensors

As shown in the figure below, it is the connection diagram of the HO-15-NP current sensor. Connect the sensor in series to the wire that needs current detection through the input and output ports, and the output terminal can collect the measured current signal; if the measured current is too small , You can set the external reference voltage. Traditional Hall sensors can only detect current signals in a specific range. If the current to be detected is larger or smaller, the sensor needs to be replaced. For the limitations of traditional Hall sensors, the HO series can change the measurement range by connecting the 8, 9, 10 and 11, 12, and 13 terminals in series. The series connection method is shown in the table below.

Figure 1HO-15-NP circuit connection diagram

The experiment measured 50 sets of data from (0-5.0A) on average, and plotted the curve as shown in the figure below. The output voltage and input current of the selected Lime HO-15-NP current sensor have a linear relationship. The experimental results verify its linearity. very high.

Figure 2 The relationship between current and voltage

For the change of measurement range, the error rate of change will change slightly, and the linear error simulation is shown in the figure below.

Figure 3 Linearity error

Generally speaking, the AC and DC current can be quickly detected by the HO-15-NP current sensor to detect the current. A single sensor can measure a variety of ranges of current, saving the cost of spare parts. It can also be used with ODC function for over-current protection.

3 Ankerui Hall sensor product selection

3.1 Product introduction

The Hall current sensor is mainly suitable for the isolation and conversion of complex signals such as AC, DC, pulse, etc. The converted signal can be directly collected and accepted by various collection devices such as AD, DSP, PLC, and secondary instruments through the principle of Hall effect. , Fast response time, wide current measurement range, high accuracy, strong overload capacity, good linearity, and strong anti-interference ability. It is suitable for current monitoring and battery application, inverter power supply and solar power management system, DC screen and DC motor drive, electroplating, welding application, inverter, UPS servo control and other system current signal acquisition and feedback control.

3.2 Product selection

3.2.1 Split open loop Hall current sensor

Table 1

3.2.2 Closed type open loop Hall current sensor

Table 2

3.2.3 Closed-loop Hall current sensor

table 3

3.2.4 DC leakage current sensor

Table 4

4 Conclusion

Through experiments, it can be known that compared with traditional Hall sensors, HO-15-NP has the advantages of wide measurable range, good linearity, high precision, convenient connection, low noise and so on. Using HO-15-NP current sensor to detect AC and DC power has superior performance. The measurement range can be changed by connecting ports 8, 9, 10 and 11, 12, and 13 in series. The linearity error will not decrease as the connection distance becomes longer. It is less affected by temperature. It is especially suitable for occasions where there are many influencing factors such as motors.