Implementation of Digital PWM on Buck-Type CSI Fed BLDC Motor Drive

Abstract

The unabating advancement in the field of permanent magnet brushless dc (BLDC)motor drive technology has made it more popular. Buck-type current source inverter has further found its place as the driver of BLDC motors due to its square-wave current injection and short-circuit tolerant essence. However, usage of the extra switch which is driven at a high frequency reduces the cost-effectiveness of the driver. Moreover, conventional pulse width modulation techniques that are implemented require a complex and costly circuits or processors. This also adds to the cost of the whole driving scheme. Due to the extra cost related to the driving scheme, BLDC motor still finds sparse applications in commercial usage. This paper has made an attempt to implement a buck-type current source inverter to drive a BLDC motor, and the control strategy is based on digital pulse width modulation. The simplicity of digital pulse width modulation makes it compatible to be implemented on a reduced cost application specific integrated circuit. The application of digital pulse width modulation and buck-type current source inverter leads to low frequency operation of all the switches present in the inverter which further minimizes the cost. With the usage of buck-type current source inverter the major snag of digital pulse width modulation that is speed stability is also addressed. The total control strategy and driving scheme is designed and verified using simulations.