This is a reference design for detecting ground fault in inverter-based drives. Inverter current is measured on both DC-positive and DC-negative bus using shunt resistors. INA149 current sense amplifier having a common-mode voltage range of +275 V is used to measure current on DC-positive bus. Current on DC-negative bus is sensed using precision operational amplifiers. The difference between the two measured currents is compared against a fixed threshold to determine the ground fault condition using high-speed comparators.
Merkmale
- Shunt-based current sensing for inverter control and protection
- Rated to measure DC-link current of +/-20 APK (design tested for +/-5 A)
- High-side current sense circuit with high common-mode voltage of +275 V supporting 100/110-Vac mains powered drives
- Calibrated high-side and low-side measurement error over operating temperature range of -10°C to 55°C < 1.5%
- Ground fault (minimum fault-current detection of 300 mA, detection time of less than 50 µs)
- Designed to be interfaced with built-in 3.3-V ADC of MCU