Simulation of sinosoidal pulse width modulation

Simulation of Sinosoidal Pulse Width Modulation (Unipolar)
Inverter
Presented by Supervised By
• Tanzeel Ahmad SP14EPE095 Dr. abdul majid
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INTRODUCTION
What is Modulation??
Modulation can be defined as the process of varying a parameter
of carrier signal in accordance with the instantaneous value of the
message signal.
• Modulation is used to reduce the size of the antenna and
increases efficiency.
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Types of modulation techniques
• FM: Frequency Modulation
• AM: Amplitude Modulation
• PM: Pulse Modulation
Types Of Pulse Modulation:
1. PWM—Pulse Width Modulation
2. PPM— Pulse Position Modulation
3. PAM— Pulse Amplitude Modulation
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What is PWM…?
Pulse-width modulation (PWM) is a modulation process
or technique used in most communication systems for
encoding the amplitude of a signal right into a pulse
width or duration of another signal, usually a carrier
signal, for transmission.
Or
The Pulse Width Modulation (PWM) is a technique
which is characterized by the generation of constant
amplitude pulse by modulating the pulse duration by
modulating the duty cycle.

Techniques of PWM
• 1. Linear modulation
• 2. Saw tooth PWM
• 3. Single Pulse Width Modulation
• 4. Multiple Pulse Width Modulation
• 5. Sinusoidal Pulse Width Modulation
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Principle
• Pulse-width modulation uses a rectangular pulse wave whose pulse
width is modulated resulting in the variation of the average value of
the waveform.
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The simplest way to generate a PWM signal is the intersective
method, which requires only a saw tooth or a triangle waveform
(easily generated using a simple oscillator) and a comparator.
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What is an Inverter ??
• An inverter is basically a device that converts electrical energy of DC
form into that of AC.
• The purpose of DC-AC inverter is to take DC power from a battery
source and converts it to AC
• The inverter receives DC supply from 12V battery and then inverter
converts it to 230V AC with a desirable frequency of 50Hz
• These DC-AC inverters have been widely used for industrial
applications such as uninterruptible power supply (UPS), AC motor
drives.
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SINUSOIDAL PULSE WIDTH MODULATION (SPWM)
• Instead of, maintaining the width of all pulses of same as in case of
multiple pulse width modulation, the width of each pulse is varied in
proportion to the amplitude of a sine wave evaluated at the Centre of
the same pulse.
• The gating signals are generated by comparing a sinusoidal reference
signal with a triangular carrier wave of frequency
• The frequency of reference signal ,determines the inverter output
frequency and its peak amplitude ,controls the modulation index ,and
Vrms output voltage
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• The inverters job is to take this input voltage and output
ac where the magnitude and frequency can be
controlled
• In order to output a sinusoidal waveform at a specific
frequency a sinusoidal control signal at the specific
frequency is compared with a triangular waveform
• The inverter then uses the frequency of the triangle
wave as the switching frequency
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PWM with Unipolar Voltage Switching
• The two types of pulse width modulation inverters are
bipolar and unipolar switching.
• Each unique switching technique creates either a
unipolar or bipolar output at the load.
• The control signals depend on comparing a reference
signal and carrier signal
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• Unipolar PWM uses a high frequency for one pair and a
low frequency for the other pair of switches
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BLOCK DIAGRAM OF THE SPWM SYSTEM
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SIMULINK MODEL OF UNIPOLAR VOLTAGE SWITCHING
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PWM PULSE GENERATOR FOR UNIPOLAR VOLTAGE SWITCHING
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GATE PULSES GENERATION FOR UNIPOLAR VOLTAGE SWITCHING
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GATE PULSES WAVEFORMS
• The PWM pulse generator block generator block
generator block generates the four PWM pulses and
these pulses are given to the gates of the MOSFET s for
turning on and turn off.
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CONCLUSION
• The electronic devices is smaller, therefore the efficiency
of power supply used in electronic devices should be
improved from time to time.
• The different switching techniques and switching
elements were used in single phase inverter also
considered when inverters become the best power
supply for converting DC power to AC power.
• Based on studied, SPWM techniques is a common
method used in single phase inverter circuit are Unipolar
and Bipolar voltage Switching.
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Applications of PWM
Servos
PWM is used to control servomechanisms.
Telecommunication
In telecommunications, PWM is a form of signal modulation where the
widths of the pulses correspond to specific data values encoded at one
end and decoded at the other.
Power delivery
PWM can be used to control the amount of power delivered to a load
without incurring the losses that would result from linear power
delivery by resistive means
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• High frequency PWM power control systems are easily realisable with
semiconductor switches
• Variable-speed fan controllers for computers usually use PWM, as it is
far more efficient when compared to a potentiometer or rheostat
• Light dimmers for home use employ a specific type of PWM control
Voltage regulation
• PWM is also used in efficient voltage regulators. By switching voltage
to the load with the appropriate duty cycle, the output will
approximate a voltage at the desired level. The switching noise is
usually filtered with an inductor and a capacitor.
Electrical
• SPWM (Sine–triangle pulse width modulation) signals are used in
micro-inverter design (used in solar and wind power applications).
These switching signals are fed to the FETs that are used in the device.
The device's efficiency depends on the harmonic content of the PWM
signal
• Another common application is in robotics where PWM signals are
used to control the speed of the robot by controlling the motors.
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Simulation of sinosoidal pulse width modulation

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Simulation of sinosoidal pulse width modulation