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Control of Brushless DC Motor

 

Sunilkumar
Raghuraman, Nandhini Santhanam, Varun Srinivasan                    Department of High
Integrity System                                                                
Frankfurt University of Applied Sciences                                                               
Nibelungenpl. 1, 60318 Frankfurt am Main, Hessen, Germany

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Abstract:  This
paper aims at implementing a way to control the speed of Brushless DC Motor
through ATMEGA32U4 controller in olimexino development board. The speed of the
motor is increased or decreased whenever the corresponding switches are
pressed. The direction of the motor is changed by decreasing the speed to zero
in one direction which will automatically changes the direction.

Keywords: BLDC motor, L6234, olimexino, Atmega32U4 controller

 

1.INTRODUCTION

The speed control
of BLDC motor is achieved by programming the OLIMEXINO-32U4 development board which
has the micro controller ATMEGA32U4. The board has the following features which
enables the feature of controlling the BLDC motor by understanding its basic
concepts.

2.SALIENT FEATURES

The olimexino
board has the following main features. They are

1.    
It
has an ATMEGA32U4 microcontroller which supports USB communication

2.    
It
can operate between the range of 5 – 12 volts

3.    
Ultra-low
power voltage regulator is present which enables to be used in battery powered
application.

4.    
It
can work in 3.3 volt and 5 volts using the jumper selection

5.    
It
has a real-time clock

6.    
It
has LED’s and Buttons which can be used for any output indication and Input
controls

OLIMEXINO-32U4 is
an ARDUINO-LEONARDO-like board with ATmega32U4. The board must not
be exposed to high electrostatic potentials. A grounding strap or similar
protective device should be worn when handling the board. Avoid touching the
component pins or any other metallic element. 
 The OLIMEXINO-32U4 board is
self-powered by the mini USB if it is connected to a USB hub of a computer.
Alternatively, it can be powered via the POWER SOURCE by 7Vdc to 12Vdc. The
bootloader starts automatically. On powering the board POWER_LED should turn
on. RXLED and TXLED should turn on and monitor the send receive on the virtual
COM port. LED1 and LED2 should start blinking. 

 

3.ATMEGA32U4
8 Microcontroller

The main part of the
OLIMEX development board is the ATMEGA32U4 controller. It has the following
characteristics. They are RISC Architecture (Reduced Instruction set),
Non-Volatile program and Data memories, On chip debug support and four-bit PMW
channels etc.

 

4.IMPLEMENTATION

            4.1.1 Arduino

            4.1.2 Control of BLDC Motor

              The speed control of
Brushless DC Motor is accomplished by using the principle of switching the
voltages of the phases of the motor in a sequence. To control the three phases
of the BLDC motor using a Motor driver IC L6234, we need three input pins and
three enable pins. These can be given as digital inputs to the IC L6234. So the
digital pins D3, D4, D5 of the olimexino is configured as output which can be
connected as input for the IC L6234 and the digital pins D6, D7, D8 are
configured as output which can be connected as enable pins for the IC L6234.The
Digital pins D10 and D11 are configured as input which can be used to connect
the buttons for controlling the increase and decrease speed of the BLDC motor.

 

 

 

4.1.2.1 Direction control

The
three inputs and three enable pins are varied in the below mentioned
commutation sequence to rotate the BLDC motor in required direction. A flag is
used to increment the states in loop which will in turn change the voltage
value to the coils in the respective sequence in loop. When the motor is
rotating in clockwise direction, the speed should be reduced to zero by the
decrease speed button and so as to continue to rotate in the counter clockwise
direction and vice versa

Add image

Clockwise
direction:

Sequence

Voltage at A

Voltage at B

Voltage at C

1

DC+

Off

DC-

2

DC+

DC-

Off

3

Off

DC-

DC+

4

DC-

Off

DC+

5

DC-

DC+

Off

6

Off

DC+

DC-

 

Counter Clockwise
Direction

Sequence

Voltage at A

Voltage at B

Voltage at C

1

Off

DC-

DC+

2

DC+

DC-

Off

3

DC+

Off

DC-

4

Off

DC+

DC-

5

DC-

DC+

Off

6

DC-

Off

DC+

Add
table number

4.1.2.2 Speed Control

            Digital
pin D10 configured as input is connected to a push button which is used to
increase the speed in certain direction. Digital pin D11 configured as input is
connected to a push button which is used to decrease the speed in certain direction.

                        Increase speed:

            A speed control variable is used to determine
the speed in which the motor is rotating. Every time the Button connected to
D10 is pressed and released, the speed value is incremented by one. The edge
triggering from zero to one of the button is detected to increase the speed
variable. During the latch of high or low the speed value is not incremented.
In the looping part of the Arduino software, the above-mentioned commutation
steps Use the table number is followed in sequence by specifying a delay
between the sequences. Whenever the speed variable is incremented, the delay
between the steps is decreased which in turn increases the speed of rotation,

                       

Decrease Speed

            A speed control
variable is used to determine the speed in which the motor is rotating. Every
time the Button connected to D11 is pressed and released, the speed value is decremented
by one. The edge triggering from zero to one of the button is detected to
increase the speed variable. During the latch of high or low the speed value is
not incremented. In the looping part of the Arduino software, the
above-mentioned commutation steps Use the table number is followed in
sequence by specifying a delay between the sequences. Whenever the speed
variable is decremented, the delay between the steps is increased which in turn
decreases the speed of rotation,

 

The speed should be
reduced to zero level in order to change the direction to the other. The motor
will get damaged if the direction is suddenly changed when motor is rotating at
high speeds. In order to prevent the damage to motor this method is followed.

            4.2 Test Program

5.STUDY
PLAN

6.REFERENCES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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