A 30-nΩ Accuracy Low Power Two-step Ratiometric Shunt Resistance Measurement System Using a Switching Regulator-based Current Generator for Shunt-based Current Sensors

This paper presents a high-precision resistance measurement system for shunt-based current sensors in battery-powered vehicles to calibrate the resistance drift of the shunt resistor due to aging. To measure the resistance of a 25 µΩ shunt resistor using a 10 Ω reference resistor with a ratio of 400,000:1, we proposed a two-step ratiometric resistance measurement technique using a second reference resistor with an intermediate resistance value. In addition to a linear regulator-based current generator (LRCG) that generates a DC excitation current for resistance measurement, a switching regulator-based current generator (SRCG) generates an AC excitation current to improve power efficiency. The implemented system demonstrates less than 0.12 % (30 nn) resistance measurement error with a 25 µΩ shunt resistor.