pwm for speed control

Hello!
I am kaushal (D5-0275-2015) &
I am mitul (05-0262-2014)
We are here to present our project work.

DEVELOPMENT OF AN ELECTRONIC
SPEED CONTROLLER USING PWM
FOR DIFFERENTIAL SPEED
APPLICATIONS

PROJECT OBJECTIVES
Generation of PWM waves using
integrated circuit
DC motor speed control with no loss
of power

“ It means, an intentional change of drive
speed to a value required for performing
the specific work process.
….by electrically
SPEED CONTROL

SPEED
CONTROL
METHODS
Flux control
Rheostat
control
Speed
controller
(PWM)
The speed controller for a DC motor works by varying the average voltage supplied to
the motor (PWM is one such speed controller where we can get varying voltage
according to the duty cycle of the PWM output signal).

DRAWBACKS OF TRADITIONAL
METHODS

DRAWBACKS
▪ constantly supplying power – wastage of
energy.
▪ Loss of energy as heat using resistors to
limit amount of current delivered to
motor.
▪ If load changes by varying pot, the
amount of current presently being
distributed over the new load and
consumed in device.
▪ Likewise, once the motor is spinning, then it
requires much less energy to maintain the
spin than it did to get it spinning- all extra
energy get wasted.
▪ Inversely, if initial supplying just enough
energy to maintain an already- motor won’t
be able to start spinning.
▪ Poor initial torque generation.

WHY PWM
▪ PWM overcome all above
drawbacks.
▪ Because we are modulating the
on/off time, rather than the
Power, this allows us to do
many things.
▪ Because of supplying full
voltage, motor get enough
initial torque.
▪ Every ON time (full 12V), motor
gets “kicks” (torque) and it
rotates faster.
▪ Switching on/off, motor
consumes average
voltage(power saving).
▪ This give changing motor speed
without any power loss.

WHAT IS PULSE?
▪ Pulse is an electromagnetic
wave or modulation of brief
duration.
▪ Types of waves: sine, square,
sawtooth, triangle.
▪ PWM uses square waves.
Various kind of waves

 Pulse- an electromagnetic wave
 Width modulation- to adjust to or keep in proper measure or
proportion the width of the pulse with respect to the frequency of
the wave.
 PWM is a duty-cycle variation methods are commonly used in
speed control DC motors.
 It is a powerful technique for controlling analog circuits digitally.
 PWM is a way of digitally encoding analog signal levels.
PULSE WIDTH MODULATION
(PWM)

DUTY CYCLE
▪ Duty cycle defined as % of ‘high’
to digital ‘low’ plus ‘digital ‘high’
pulse width during a PWM
period.
▪ On-time is the timing which DC
supply is given to load while
the “off-time” is the time
during which it is switched off.
𝐷𝑢𝑡𝑦 𝐶𝑦𝑐𝑙𝑒 (%) =
𝑂𝑛 𝑇𝑖𝑚𝑒
𝑃𝑒𝑟𝑖𝑜𝑑
𝑥 100
Avg. Voltage= D x VH

DUTY CYCLE
▪ This figure shows the pulses
with 0% through 100% duty
cycle.
▪ The average DC Voltage value
for 0% duty cycle is zero.
▪ The maximum duty cycle can be
100%, which is equivalent to a
DC waveform.

 It control works by switching the power
supplied to motor ON and OFF very
rapidly.
 DC volts is converted to a square wave
signal, altering between fully on (nearly
12V) and ZERO.
 It give the motor a series of power
“kicks”.
 It can overcome the problem of poor
starting performance of a motor.
PWM PRINCIPLE
 Instead of supplying a varying voltage
to a motor, it supplies fixed voltage
(such as 12V) which starts it spinning
immediately.
 The voltage is then removed and the
motor “coasts”.
 By continuing this voltage ON/OFF
cycle with varying duty cycle, the motor
speed can be controlled.

PWM METHODS
In our project , We applied DISCRETE IC method
1
ANALOG
METHOD
2
DIGITAL
METHOD
3
DISCRETE IC

It can
greatly
reduce cost
The motor
consumes
less power
Significantly
less energy
loss due to
heat
Allows finer
tuning
control of
motor
It can
overcome the
problem of
poor starting
performance
of a motor
ADVANTAGES OF PWM

CAPACITOR
BATTERY
INTEGRATED CIRCUIT
DIODE
RESISTOR
MOTOR
MAJOR COMPONENTS
MOSFET

INTEGRATED CIRCUIT
(IC CD4093)
▪ It is a heart of circuit.
▪ It is a sets of electronic circuits
integrated together for desired
work.
▪ It is made of silicon
(semiconductor material).
▪ It is smaller , cheaper and
faster than other large
electronic components.
▪ Use: computers, mobiles,
digital appliances
1

IC PIN CONFIGURATION
▪ This IC having four nand gates (U1a, U1b,
U1c, U1d).
▪ IC converts DC into pulse shape.
SYMBOL PIN DESCRIPTION
1A to 4A 1, 5, 8, 12 Input
1B to 4B 2, 6, 9, 13 Input
1Y to 4Y 3, 4, 10, 11 Output
VDD 14 Supply voltage
VSS 7 Ground (0 V)

MOSFET
(IRFZ44N)
▪ Automatic switching device
▪ Three terminals: gate, drain,
source.
▪ Application:
▹ Switch, speed control of dc
motor, auto intensity control of
street lights
2
G D S

DIODE
(1N4007-1N4148)
▪ To allow electric current to pass
in one direction, and block in
reverse direction.
▪ Kind of NRV.
▪ This unidirectional behavior
called rectification.
▪ Also used to convert AC to DC.
3
1N4007 1N4148

CAPACITOR
(103-104)
▪ To store electrical energy and
release when required to
circuit.
▪ It is used as a motor starter.
▪ Used for filtration; especially in
removing ripples from rectified
waveform (DC waves).
4
103- 10nF
104- 100nF

RESISTOR
(10K-100K)
▪ It implement electrical
resistance as a circuit element.
▪ To reduce current flow, divide
voltage, adjust signal levels.
▪ Types: fixed and variable
resistors.
5
Fixed resistor
Variable resistor

BATTERY
(12V 5A)
▪ It is used for power supply to
circuit with capacity of 12V and
5A.
6

MOTOR
(12V)
▪ Machine to converts electrical
energy into mechanical energy.
▪ Rating: 12V DC 1A.
▪ Type: DC Shunt Motor
▪ Application: when the driven load
requires a wide range of speed
control.
▪ Used in many agricultural m/c.
7

WORKING OPERATION
▪ IC CD4093 is a heart of circuit.
▪ Out of the four nand gates inside the 4093, U1a is to work as an adjustable duty
cycle by generating switching pulses.
▪ The U1b, U1c, U1d buffers the output of the adjustable duty cycle to drive the
switching MOSFET.
▪ The MOSFET drives the DC motor according to the switching pulses.
▪ When resistor is varied, the Duty cycle varies and so do the change in speed of
the motor.
▪ Diode act as a freewheeling diode.
▪ IC should be mounted on a holder.
▪ The 12V power supply for this circuit must be able to handle at least 5A.

Place your screenshot here
Project
work
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OBSERVATIONS
SR. NO
APPLIED
VOLTAGE (V)
DUTY
RATIO (%)
OUTPUT
VOLTAGE (V)
SPEED (RPM)
1 12 27 3.26 1045
2 12 28 3.43 1060
3 12 30 3.60 1080
4 12 38 4.58 3000
5 12 53 6.40 4423
6 12 58 7.00 4593
7 12 63 7.00 4690

CALCULATIONS Supply voltage = 12V
Total time division in oscilloscope = 7
On time division= 1.9
𝑑𝑢𝑡𝑦 𝑟𝑎𝑡𝑖𝑜 =
𝑜𝑛 𝑡𝑖𝑚𝑒
𝑡𝑜𝑡𝑎𝑙 𝑡𝑖𝑚𝑒
𝑥 100;
𝑎𝑐𝑡𝑢𝑎𝑙 𝑣𝑜𝑙𝑡𝑎𝑔𝑒
𝑠𝑢𝑝𝑝𝑙𝑦 𝑣𝑜𝑙𝑡𝑎𝑔𝑒
=
1.9
7
𝑥 100
= 𝟐𝟕. 𝟏 %
𝐴𝑐𝑡𝑢𝑎𝑙 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 = 𝑠𝑢𝑝𝑝𝑙𝑦 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑥 𝑑𝑢𝑡𝑦 𝑟𝑎𝑡𝑖𝑜
= 12 𝑥
27.1
100
= 𝟑. 𝟐𝟔 𝑽
Speed = 1045 rpm

CALCULATIONS
Supply voltage = 12V
On time division= 2
𝑥 100;
=
2
7
𝑥 100
= 𝟐𝟖. 𝟔 %
= 12 𝑥
28.6
100
= 𝟑. 𝟒𝟑 𝑽
Speed = 1060 rpm

CALCULATIONS
𝑥 100 ;
=
2.1
7
𝑥 100
= 𝟑𝟎. 𝟎 %
= 12 𝑥
30.0
100
= 𝟑. 𝟔𝟎 𝑽
Speed = 1080 rpm

CALCULATIONS
Total time division in oscilloscope = 6.5
𝑥 100;
=
2.48
6.5
𝑥 100
= 𝟑𝟖. 𝟐 %
= 12 𝑥
38.2
100
= 𝟒. 𝟓𝟖 𝑽
Speed = 3000 rpm

CALCULATIONS
𝑥 100;
=
3.2
6
𝑥 100
= 𝟓𝟑. 𝟑 %
= 12 𝑥
53.3
100
= 𝟔. 𝟒𝟎 𝑽
Speed = 4423 rpm

CALCULATIONS
𝑥 100;
=
3.8
6
𝑥 100
= 𝟔𝟑. 𝟑 %
= 12 𝑥
63.3
100
= 𝟕. 𝟔𝟎 𝑽
Speed = 4690 rpm

ANALYSIS
1045 1060 1080
3000
4423
4593 4690
0
1000
2000
3000
4000
5000
6000
3.26 3.43 3.60 4.58 6.40 7.00 7.60
RPM
VOLTAGE
VOLTAGE VS. SPEED
rpm Linear (rpm)

• 4700 RPMMaximum motor
speed
• 1000 RPMMinimum motor
speed
• 7.6VMaximum output
voltage
• 3.2VMinimum output
voltage
• 27-70%Controlled duty
ratio range
RESULTS

“
▪ From application point of view, this project will be very useful
for various machines which require variable speeds and in
agricultural machineries in particular.
▪ We found that the circuit we designed was applicable up to
1A rating.
▪ If any agricultural machinery having rated power or currents
beyond 1A, then the same circuit design can be implemented
with increased source and components ratings along with
enough capable source.
APPLICATION

“ ▪ The main advantage is there was minimal loss of power in
PWM technique as compared to other speed control
techniques.
▪ We found out that this is very cheap and efficient speed
control method where all components give reliable operation.
▪ This circuit is useful to operate the dc motors to achieve
different speeds with very low losses and low cost.
▪ The circuit response time is fast. Hence high reliability can be
achieved.
CONCLUSION

ER. J. SRAVAN KUMAR
Project Advisor,
Assistant Professor,
Dept. of Basic Engineering Applied Sciences,
College of Agricultural Engineering & Technology,
AAU, Godhra
Special thanks to….

REFERENCES
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