【 Application Sharing 】 High sensitivity current sensing module test application case

In recent years, the application scale of the Internet of Things in the industrial field continues to expand, the degree of intelligence is getting higher and higher, followed by higher and higher requirements for the most front-end sensor of information collection.

Share a case of testing and application of load and power supply of Feith Technology in high-sensitivity and high-power density current sensor modules by a global leader in magnetoelectric sensors. The company's products and solutions are applied in the field of transportation, energy and automobile.

Problems encountered by customers:

1. DC large current sensor is affected by temperature, time, position, external magnetic field and other factors, resulting in the sensor accuracy error is common. The accuracy and stability of DC high current measurement has a direct impact on production equipment, personnel safety and production efficiency.

2. At present, there is no technical specification for the calibration of current sensors (either those that turn high current into low current output (e.g. LEM sensor) or current sensors that turn into voltage output (e.g. Roche coil).

3. During the calibration of the current sensor, the current direction should be switched between positive and negative.

4. Low-voltage, high-current, high-power DC power supply needs long service life, small ripple and high precision.

Faith's solution:

The traditional large current sensor measurement, the large current according to a certain proportion of the device into a small voltage output, in the actual calibration process need to switch the direction of the current, to the operator caused a great obstacle, not only affect the work efficiency, but also lead to a lot of test bed error, and even cause the damage of the test bed. Therefore, the urgent problem to be solved is to find a high current sensor calibration method with good applicability.

Faith uses high-power load and high-precision DC source to test the sensor, which is more accurate, faster, more convenient, more automatic and lower cost than the simple DC power test.

The advantages of FTG120/240 series power supply and FT68200 series load in this case:

1. High precision

FTG120-010 and FTG240-010 are precision switching power supplies with a precision of up to 0.1%. At the same time, they have the characteristics of constant voltage and constant current, which greatly facilitates the testing of sensors.

2. Small ripple

Generally, it is difficult to guarantee the control index after power short circuit, and the large ripple value will cause sensor induction bias, resulting in zero calibration parameters cannot be realized.

FTG120-010 and FTG240-010 have voltage ripple V(p-p) less than 55mV and V(rms) less than 20mV.

3. High stability

FTG DC power supply has less changes caused by the influence of external environment, and the voltage adjustment rate + system adjustment rate is less than 0.01%, with good repeatability.

4.High overload

The FT68212E-150-1200 load has the pulling capacity of twice the instantaneous over power.

5. High pulling accuracy

Faith FT68200 series load basic accuracy of 0.05%;

The ripple coefficient is less than 0.01%;

Low temperature drift coefficient. Imported current sampling material is used for the load of Faith FT68200, with a temperature drift coefficient of 10ppm. And the use of distributed control (the current is distributed control and sampling, and then summary processing. The radiator is designed through the wind tunnel. Under the condition of fan rotation, the temperature rise of manganese copper wire will not exceed 20℃. Ensure the precision of loop control.

6 Automate

The load has sequential and automatic testing capabilities. The load will automatically test multiple steps, automatically judge whether the sensor output voltage corresponding to the current value in each step is within the range, and give the judgment of each step and the overall.

7. Zero point adjustment

The leakage current of the load itself is in the microampere level, which can be well calibrated to zero.

8. Current direction is switched between positive and negative

Current commutator box FT-TW1500A can provide automatic current commutation function. The control interface type is relay. The voltage and current of the control interface are 24V and 50mA respectively.