Design and implement of intelligent variable frequency drive

Abstract

Variable voltage variable frequency (VVYF) or V/f is the most common method of speed control of three phase induction motors. Majority of those operate in applications not requiring high accuracy position control or high accuracy speed control. A variety of v/f drives are available in market and the speed, acceleration time ,deceleration time are set manually .The key feature of the proposed v/f drive is it's ability to sense the external environment and take decisions intelligently. This is ideal when considering a production line. Automation of an induction motor for a particular production line can be done easily with this v/f drive. The brain of this drive is a Peripheral Interface Controller (PIC). It has 3 PWM outputs. PIC was programmed in assembly language .MPLAB software compiles assembly to hex codes. Three PWM signals generated from PIC are sent to three IGBT drivers which are capable of introducing interlock in order to drive one IGBT on the same leg. The signals are sent through four opto couplers to isolate the controller from disturbances from power side. A speed reference is provided by a potentiometer connected to analog channel. When a speed is input by potentiometer, interrupt service routine activates and the motor could be run at that speed. Numerous other applications are possible with this drive in industry, One is dispenser controller. Another application is flow contr Her and many more. However further research could develop the features of this controller particularly the closed loop feature.