Life Model for PWM Controlled Induction Motor Insulation using Design of Experiments Method

Abstract

According to numerous industrial surveys, the failure rate of stator insulation is much higher for Pulse Width Modulated (PWM) controlled induction motors than for the motors with sinusoidal voltage supply. Voltage spikes, high slew rate of spikes, and repetition and harmonics of PWM voltages generate higher electrical and thermal stresses in motor insulation that result into premature failure. In this paper, the Design of Experiments (DoE) method has been proposed to estimate the life of PWM controlled induction motor insulation. The insulation stress under PWM voltages is quantified by three factors viz. spike magnitude, spike frequency and voltage harmonics factor. These stress factors are experimentally computed for PWM controlled induction motor at different switching frequencies. Keeping these stress factors as input, a fuzzy logic model for insulation life is subsequently developed. This model is fine tuned to match the results obtained through insulation aging test with PWM voltages. The fuzzy logic data is analyzed by statistical techniques such as, ANOVA and Standardized Pareto Chart. A full factorial Design of Experiments technique is then applied to the fuzzy logic results to get the first order model relating the insulation life of induction motor with the stress factors. This model can be directly used for insulation life estimation of PWM controlled induction motors.

Keywords:

• aging test
• design of experiments
• fuzzy logic
• insulation
• life model

Additional information

Notes on contributors

Triloksingh G. Arora

Triloksingh G. Arora received the B.E. degree in Electrical Engineering from the Government College of Engineering, Amravati, India, in 1983 and M.Tech. degree from Visvesvaraya Regional College of Engineering, Nagpur, India, in 1985. He completed Ph.D. in 2016 in the area of High Voltage Engineering. After his post graduation, he worked as a Jr. Engineer in Maharashtra State Electricity Board, Chandrapur, for one year and then joined Visvesvaraya Regional College of Engineering, Nagpur, as Research Assistant. He joined the Electrical Engineering Department of Shri Ramdeobaba College of Engineering and Management, Nagpur (India) as a Lecturer in 1986. Presently, he is working as Associate Professor in Electrical Engineering Department at Shri Ramdeobaba College of Engineering and Management, Nagpur (India). He is Fellow of Institution of Engineers (India). His fields of interest are high voltage and insulation engineering, power system protection and numerical relays.

Mohan V. Aware

Mohan V. Aware received the B.E. degree in Electrical Engineering from the Government College of Engineering, Amravati, India, in 1980, M.Tech. degree from the Indian Institute of Technology, Bombay, India, in 1982, and Ph.D. from Visvesvaraya Regional College of Engineering, Nagpur, India, in 2002. After his post graduation, he worked as a Design Officer with Crompton Greaves Ltd., Nasik India and as a Development Engineer with Nippon Denro Ispat, Nagpur, India. In 1991, he joined the Visvesvaraya Regional College of Engineering, as a Lecturer. From 2001 to 2003, he was a Research Associate with the Electrical Engineering Department, Hong Kong Polytechnic University, Kowloon, Hong Kong. Presently, he is working as a Professor of Electrical Engineering at Visvesvaraya National Institute of Technology, Nagpur (India). He is member of Bureau of Energy Efficiency (BEE) and recognized Energy Auditor. His fields of interest are high voltage engineering and electric drives.