The design enables isolated measurement of high AC currents while providing an analogue output for monitoring and control applications.
The reference design offered by Vishay is used for measuring high AC currents in applications like EV power trains, battery monitoring systems, charging stations, motor control systems, and power supplies. This design provides the capability of measuring AC current with a maximum value of 1415A continuously. It also has a maximum working isolation voltage of 1200VRMS and offers an isolated single-ended analogue output of 0V to 2.5V. Other specifications include bandwidth of around 280kHz and low temperature offset and gain drift.
Current is measured by sensing the voltage developed across a low-resistance busbar shunt resistor in a high voltage environment. The sensed signal is sent to an isolated differential amplifier, which has a linear differential input range of ±50mV and a differential output range of ±2.05V. The differential output of the circuit is then converted to single ended output which can be directly connected to the ADC or multimeter.
For improving the accuracy of measurement, a low-pass RC filter is used prior to the isolation stage in the circuit. Resistor and capacitor are chosen such that the effect of voltage drop due to input bias gets minimized, and balanced impedance at positive and negative input terminals is maintained. ESD protection is included in the design to ensure that the isolation stage is protected from transients and electrical disturbances.
The busbar shunt resistor features an all-welded construction along with ultra-low resistance, ultra-low inductance, and ultra-low thermal electromotive force.
Based on the sensing element chosen, it measures currents up to 1415A continuously based on the sensing element selected, it can measure currents up to 1415A continuously and supports higher current levels for short-duration operation.
The kit contains the reference design board along with the files and documentation necessary to evaluate and develop isolated current-sensing applications. The design is intended for applications requiring accurate current measurement and galvanic isolation in high-voltage environments.
Vishay has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.
