Design and Manufacture of a Circuit for Brushless DC Motor Driving Using Sensorless Control Techniques
Panagiotis Katopodis
Abstract
The last years the use of brushless motors has expanded to the industrial applications as well as the market of domestic appliances, air conditionings and car industry due to their high performance, silent function and low demand for maintenance. This diploma thesis analyzes at the beginning the main elements of a drive circuit BLDC motor, called ESC (Electronic Speed Controller) and the 3-phase inverter. After that, drive techniques of the motor are presented, which are separated in sensorless (without use of sensor) and sensored (with use of sensor) techniques. In order to reduce the cost and complexity of the drive circuit, drive without sensor has been preferred. The method that has been used in the construction part is based on the BEMF voltage, which is produced at the rotation of the motor for the tracking of the zero crossing points of this voltage. This way it is possible the transport of six steps with electronic transporter (3- phase inverter) for the rotation of the motor. Other methods of tracking place of BLDC motor are analyzed, besides the method of Zero Crossing Points (ZCPs). Further on it is analyzed the Pulse Width Modulation signal (PWM) and various forms of the PWM signal. Special emphasis is given on techniques based on the PWM signal for checking the 3-phase inverter and the BLDC motor. In addition control strategies of a permanent magnet, which is found inside BLDC motor, are analyzed. In the construction part of the thesis the diagram and the Printed Circuit Board (PCB) are presented, which have been designed using the Altium Designer program. Further on, the main elements of the circuit are analyzed, and special emphasis is given on the microprocessor ATmega328, which is the “brain” of the drive circuit. Also it is presented and analyzed the software used for programming the microprocessor in order to check the motor. Finally the thesis is completed with some conclusions and results from the construction part.