A digital current sensor for PWM inverters

A digital current sensor having the properties of high accuracy, high speed, and low cost for measuring the output current of a pulse-width-modulated (PWM) inverter is described. The digital current sensor forms a closed-loop current sensor with a tracking-type analog-to-digital converter. A prototype digital current sensor of 12 bits is developed and excellent experimental results are shown in the case when an input current of an induction motor (2.2 kW) driven by a PWM inverter is measured by the digital current sensor. >