Harmonic Analysis of Universal Motor Supplied by Single Phase PWM Inverter-Fed Drive

Abstract

Universal motor is a series DC motor that can be operated by both AC and DC supply. These are commonly used in small household appliances and control circuits for industrial processes. Speed of universal motor is controlled using power electronic interface such as TRIAC and variable frequency drives. Single phase PWM inverter is common technique for supply when universal motor operates on AC. Harmonics are generated due to use of power electronic circuits. These harmonics may affect performance of other components connected to supply system and should be kept below 5% as suggested by IEEE standard 519. In this paper, harmonic analysis of single phase PWM based inverter fed universal motor is presented. SIMULINK® and SIMSCAPE® environments of MATLAB® are used as simulation platform. Experimental results are obtained for validation of simulation results. Harmonic analysis show that THD for both voltage and current are in excess of the limit set by IEE standard 519. Further it is observed that THD decreases when carrier frequency is increased for PWM of inverter.