Measuring Average Current through Inductive Loads via Triangle Approximation Integration Using a Microcontroller

Abstract

The aim of this study is to analyze from point of view of accuracy the method of software integration using a microcontroller for measuring the average current through an inductive load driven with pulse-width modulation. It involves measuring the voltage on a series shunt resistor taking samples at the two edges of the drive signal and performing integration in software using triangle approximation. The influence of the relation between the driving frequency and the load’s inductance/resistance (L/R) time constant is studied as well as the hardware and software elements that introduce measurement errors. The study confirms the method provides an easy and feasible way of measuring average current in the appropriate context.