Variable Speed Drive For Brushless DC Compressor


Tay, Siang Hui (2003) Variable Speed Drive For Brushless DC Compressor. Masters thesis, Multimedia University.

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This paper presents variable speed drive method for DC Brushless compressor. The trend for air conditioning system is aiming for energy efficiency. This is achieved by utilizing a more efficient compressor and variable speed drive method. As the Compressor is dealing with high variance of temperature range, conventional sensored method for driving a Dc Brushless motor is not practical. A sensor-less method is utilized for this system by detecting the back EMF. A prototype of the driver is built by using the circuit CAD software PROTEL The circuit is designed on the Advance Schematic of PROTEL and the printed circuit board layout is designed with Advance PCB of PROTEL. A micro controller is programmed with ANSI C language with reference to application software provided by the micro controller vendor. Electromagnetic compatibility test for harmonics and conducted emission is performed on the prototype. A few solutions for harmonics counter measure is produced and tested. A noise filter is designed for counter measure of conducted emission noise. The compressor to be controlled in this project is a DC Brushless motor with concentrated winding stator design and interior permanent magnet rotor design. A number of driving methods have been considered. The 120 degrees commutation, sensorless back EMF detection, full control on the full bridge three-phase inverter circuit techniques is employ in this motor driving scheme. Speed control of the system is achieved by PWM technique. Torque and speed regulation by PID control are also reviewed. Fine-tuning of the efficiency of the motor is achieved by lead-angle control method. Simulation by a commercially available software package SIMCAD by Power Simulation Inc. is used to simulate the drive condition. The simulated results are compared with the actual results. The solutions for various harmonics counter measure methods are compared. A complete motor driving system is built. The sesign allows the flexibility for further expansion and improvement through software upgrades. This method reduces time-consuming hardware redesigning and testing. The design also maximizes cost versus features of the driver as most of the additional features are realized through software implementation.

Item Type: Thesis (Masters)
Subjects: L Education > LB Theory and practice of education > LB2300 Higher Education
Divisions: Faculty of Engineering (FOE)
Depositing User: Mr Shaharom Nizam Mohamed
Date Deposited: 04 Dec 2009 07:40
Last Modified: 04 Dec 2009 10:23


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