Solar Powered BLDC Motor Drive for Wide Speed Range Electric Vehicle Application

Abstract

Brushless DC (BLDC) motors are the special type of permanent magnet (PM) `ac fed dc motors' with trapezoidal back EMF. Nowadays, use of BLDC motors in automotive and an agricultural water pumping application is proliferating by using solar power source directly or along with battery storage. In automotive application the BLDC motor need to be operated within full speed range. To achieve this wide speed range operation of BLDC motor supplied through solar power, a novel drive is proposed so as to utilize the best possible combination of pulse amplitude modulation (PAM) and pulse width modulation (PWM) techniques. A PWM controlled buck-boost converter which is used as a front-end converter achieves a variable DC link voltage, acting as PAM control and the motor side inverter is controlled by PWM technique. When used alone, the motor side inverter operates with very high switching frequency to get larger speed which gives rise to higher back emf and results in failure of BLDC motor operation. It also increases the switching loss and mechanical stress on switching devices. The proposed control algorithm decides the contribution of PAM and PWM to control dc link voltage and inverter output voltage to get desired motor speed response.