ADJUSTING MOTION OF BRUSHLESS DC MOTOR THROUGH MICROCONTROLLER.

Bhavana Nili 1 , Deepali Kapadnis 2 , Vivek Sonawane 3 and Vijaya Aher 4 . Electronics and Telecommunication Dept. Vishwakarma Institute Of Information Technology, Pune, Maharashtra, India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


Fig 1:-Fundamentals Of Bldc Motor
The BLDC motor is form on a basic principle of magnetism, which tells us that similar poles repulse each other, while facing poles attracts. As fig1 illustrate, it generate a magnetic field with a polarity that creates torque, when a current is passed through two coils. When a current is passed, the rotor rotates. When the rotor reaches a definite position, the direction of the current is changes so that the torque continues further in the same direction. When required the direction of current is changed again to continuous generation of torque. But, instead of two coils, actual BLDC motor typically use six coils positioned 60 degrees apart. Then, two coils at a time can be excited to create a torque enough to move the rotor to the required position.When this position is reached, other coils are energized in continuous manner producing the torque.

Fig2:-Block Diagram For Speed Controlling Of Bldc Using Microcontroller
Hardware description:-PIC Microcontroller:-It is the central processing unit of the system. In this operation, the microcontroller plays an important role. Output signals of Hall-effect sensors perform as external interrupts. The microcontroller makes switching device turn on and turn off alternatively.
The microcontroller responds to the interrupt based execution and changes the state of the output pin accordingly. The microcontroller gets three input signals, one from each Hall sensor, and has six output pins; one for each switching driver.
LCD display:-Here we are using 16x2 LCD as the display device. Following are its feature: 1. It can show 16 characters 1st line and16 characters 2nd line. 2. A 330-ohm resistor is used for contrast control of LCD. 3. The LCD has three control lines of which 2 are connected to port B of the microcontroller. 4. 8 Data lines are used for transferring data from the microcontroller to LCD. 5. The LCD is used in 8-bit mode & 8 data lines are connected to port B of the microcontroller.

Table No.1:-Comparison Of Lcd
Optoisolator:-Opto-isolator is a component that combines or split transmission data from optical fibers. An optoisolator which transfer electrical signals in the form of light wave there is isolation between input and output. Optoisolator prevents high voltage on one side of a circuit and damaging component on the other side of the circuit. An Optoisolator which converts electrical input signal into light.

Speed sensor (Hall Effect sensor):-
A Hall Effect is a transducer that changes its output voltage in response to a magnetic field. Hall Effect sensor is used for presence switching, speed detection, positioning and current sensing applications. It is mostly used to time the speed of wheels and shafts, such as for internal combustion engine ignition timing, tacheometer and anti-lock braking systems. Hall Effect sensor used for BLDC motor for the positioning of rotor.

Fig 3:-Voltage Source Inverter (3 Phase Configuration
The two pole voltages of the single-phase bridge inverter generally have same magnitude and frequency but their phases are 180 degree apart. Thus the load connected between these two poles outputs between A and B will have a voltage equal to twice the magnitude of the individual pole voltage. The pole voltages of the 3 phase inverter bridge are phase apart by 120 degree each.

Methodology:-
Pulse width modulation is a mainly used technique for controlling motion/speed of motors. The advantage of PWM is that power loss in the switching device is very low. PWM works also well with digital controls which is because of their ON/OFF nature, and can easily set the needed duty cycle. The duty cycle determines the speed of the motor. The desired speed can be obtained by changing the duty cycle. The PWM in microcontroller is used to control the duty cycle of BLDC motor.