An Indirect Estimator of Speed for a DC Motor Embedded in an Automotive Combustion Engine

Cesar Da Costa,Paulo Bressan

doi:10.24018/ejers.2020.5.9.2096

Abstract

This paper develops an estimator of speeds indirect for a DC motor embedded in an electrical water pump installed in internal combustion engines. The benefit of this technique is that the estimation framework doesn't require a dynamometer or machine-like coupling. The test results were based on the Motor Current Signal Analysis (MCSA) technique that is commonly used in an AC motor and has a great performance for measuring the rotational speed of electric motors. Two tests were used, one with DC motors using a dynamometer to validate the indirect reading of the rotation and another using the indirect estimator of speed developed in this work. This technique had positive results, regardless of the type of current sensor used. The preliminary outcomes from a research center model were introduced to justify the practicality of the proposed estimator of speed.

Highlights

With investments in research and development, the automotive sector moves to create new solutions or often improves existing solutions to reduce pollutant emissions and increase the energy efficiency of their vehicles
Some solutions seek to reduce loads that are coupled to the combustion engine in that, if mechanical elements are replaced by electromechanical elements, such as the water pump that is normally driven by an attached belt, has the possibility of being replaced by a DC motor [1],[2]
The contribution of this work is the development of a measuring device for indirectly reading the real time speed of DC motors embedded on devices installed in internal combustion engines

Summary

INTRODUCTION

With investments in research and development, the automotive sector moves to create new solutions or often improves existing solutions to reduce pollutant emissions and increase the energy efficiency of their vehicles. Yifan reported three ways of indirectly measuring the brush route of brushed DC motors were presented Their conclusion regarding the application was that the period and spectrogram estimation methods are suitable for analysis only if the armature current is stable, and a packet analysis, Wavelets, is suitable for analysis of the constant current and starting current of the armature. The contribution of this work is the development of a measuring device for indirectly reading the real time speed of DC motors embedded on devices installed in internal combustion engines. As indicated by Ohm's Law, the voltage over the resistor and voltage over the inductor is proportional to the difference in current Ia through the coil La regarding time, and the back EMF Ec can be composed as an element of the rotation speed Wa and a constant Kv controlled by the flux of permanent magnets.

DC Motor Mathematical Model

Spectral Analysis through FFT

Sensorless Speed Measurement

RESULTS AND CONCLUSIONS