Performance Evaluation of Inverter-equipped Drive to Regulate the Speed of Motor and Cooling Output of Air Conditioner

Abstract

The Inverter-equipped Drive designed and constructed in this paper adopts a solid state electronic conversion system using Variable Voltage Variable Frequency (VVVF) control method coupled with AC - DC Converter and DC - AC Converter technology. The method involves the assemblage of DC Power Supply Unit, Monitoring and Control Units and Power Unit. The DC Power Supply Unit in the design supplies power to the entire system by converting the incoming 230VAC of fixed 50Hz into 150VAC through a step - down transformer. A bridge rectifier converts the transformer output voltage to a varying DC voltage, which in turn is passed through an electronic filter to convert it to an unregulated DC voltage. This DC voltage is then converted back into AC voltage through the use of IGBT electronic power transistors using Pulse Width Modulation (PWM) technique. The entire process is controlled by a microcontroller (PIC18F4431) which monitors the incoming voltage supply, speed set-point, DC link voltage, output voltage and current by sampling the current ambient air temperature and adjust the speed of the compressor appropriately. The results showed the corresponding actual speeds, frequencies, the current drawn by the motor, stator voltage, consumption power, and torque - characteristics are observed for both conventional and inverter-equipped drive air conditioner.