‫(رقم المحاضرة)‬

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Project members
 Khaled Ragab Saad

 Mohamad Ashraf Saad

 Mohamed Hamada Mohamed

 Mohab Mohamad Mostafa

 Ahmed Mohamad Hasan

 Ahmed Ragab Desouky

 Mazen Yosry Abd El Hameed

 Mahmoud Abd El Monsef Hassan

 Mohamed Hesham Farouk

Project Supervisors

Dr. Mohamed El Ameer & Dr. Amr El Gendy

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Table of Contents

1. Purpose of the project…………………………..3

2. Types of inverters……………………………....8
3. Project idea and working principle…………….11
4. Oscillators………………………………………15
5. Crystal oscillator………………………………..19
6. Phase-Locked Loop (PLL)……………………..21
7.

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

-What does a power inverter do, and what can I use one for?
A power inverter changes DC power from a battery into conventional
AC power that you can use to operate all kinds of devices ... electric
lights, kitchen appliances, microwaves, power tools, TVs, radios,
computers, to name just a few. You just connect the inverter to a
battery, and plug your AC devices into the inverter ... and you've got
portable power ... whenever and wherever you need it.
The inverter draws its power from a (12-24 Volt) battery (preferably
deep-cycle), or several batteries wired in parallel. The battery will need
to be recharged as the power is drawn out of it by the inverter. The
battery can be recharged by running the automobile motor, or a gas
generator, solar panels, or wind. Or you can use a battery charger
plugged into an AC outlet to recharge the battery.

-Using an Inverter for Emergency Home Backup Power.

A very simple way to use an inverter for emergency power (such as
during a power outage), is to use a car battery (with the vehicle
running), and an extension cord running into the house, where you can
then plug in electrical appliances.

-Integrating Renewable Energy Sources.

In solar power systems, for instance, the electricity generated by

photovoltaic panels is DC, but home appliances and the grid use AC.
An inverter enables this DC-to-AC conversion, ensuring that solar
energy can be utilized efficiently within the home or fed into the
electrical grid
-What size inverter should I buy?
We carry many different sizes, and several brands of power inverters,
The size you choose depends on the watts (or amps) of what you want
to run ,We recommend you buy a larger model than you think you'll
need (at least 10% to 20% more than your largest load).
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*Example: You want to power a computer with a 17" monitor, some
lights, and a radio.

Computer 300 Watts

2 - 60 Watt lights 120 Watts
Radio 10 Watts
Total Needed 430watts

For this application, you would minimally need a 500 W inverter, and should give
some thought to a larger one, as there will likely be a time when you wish you'd
bought a bigger model ... in this example, you might decide you'd like to run a fan
while you compute, or let the kids watch TV.
Helpful formulas:
-To Convert AMPS to WATTS:
Multiply: AMPS X 220 (AC voltage) = WATTS
This formula yields a close approximation of the continuous load of the appliance
-To Calculate approximate Startup Load:
Multiply: WATTS X 2 = Starting Load

Most often the start up load of the appliance or power tool determines whether an
inverter has the capability to power it.

*For example, you have a freezer with a continuous load of 4 amps, and a start up
load of 12 amps:

4 amps x 220 volts = 880 watts continuous

12 amps x 220 volts = 2640watts starting load

You would need an inverter with peak-surge rating greater than 2640 watts.

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-Do I need Modified Sine Wave, or Pure Sine Wave?
Advantages of Pure Sine Wave inverters over modified sine wave
inverters:
a) Output voltage wave form is pure sine wave with very low harmonic
distortion and clean power like utility-supplied electricity.
b) Inductive loads like microwave ovens and motors run faster, quieter
and cooler.
c) Reduces audible and electrical noise in fans, fluorescent lights, audio
amplifiers, TV, Game consoles, Fax, and answering machines.
d) Prevents crashes in computers, weird print out, and glitches and
noise in monitors.
e)Reliably powers the following devices that will normally not work
with modified sine wave inverters:

 Laser printers, photocopiers, magneto-optical hard drives

 Certain laptop computers (you should check with your
manufacturer)
 Some fluorescent lights with electronic ballasts
 Power tools employing "solid state" power or variable speed control
 Some battery chargers for cordless tools
 Some new furnaces and pellet stoves with microprocessor control
 Digital clocks with radios
 Sewing machines with speed/microprocessor control
 X-10 home automation system
 Medical equipment such as oxygen concentrators

-In the market of power inverters, there are many choices. They
range from the very expensive to the very inexpensive, with varying
degrees of quality, efficiency, and power output capability along
The way. High quality combined with high efficiency exists, though
it is often at a high monetary cost. (1)

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  Average price of inverter in Egypt (2)

Power (Watt) Average price(Egyptian pounds)

500 5000~6000

1000 10000~12000

1500 14000~16000

2000 17000~19000

2500 21000~24000

3000 25000~26000

4000 27000~28000

5000 28000~30000

10000 50000~60000

 Our goal is to fill a niche which seems to be lacking in the power

inverters market, one for a fairly efficient, inexpensive inverter with a
pure sine wave output. Utilizing PWM and analog components, the
output will be a clean sinusoid, with very little switching noise,
combined with the inexpensive.

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
Inverter can be classified into many types based on :

a-The Output Characteristic

According to the output characteristic of an inverter, there can be

three different types of inverters.

 Square Wave Inverter

 Sine Wave Inverter
 Modified Sine Wave Inverter

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1) Square wave inverter

The output waveform of the voltage for this inverter is a square wave.
This type of inverter is least used among all other types of inverter
because all appliances are designed for sine wave supply. If we supply
square wave to sine wave based appliance, it may get damaged or
losses are very high. The cost of this inverter is very low but the
application is very rare. It can be used in simple tools with a universal
motor.

2) Sine wave

The output waveform of the voltage is a sine wave and it gives us a

very similar output to the utility supply. This is the major advantage of
this inverter because all the appliances we are using, are designed for
the sine wave. So, this is the perfect output and gives guarantee that
equipment will work properly. This type of inverters is more expensive
but widely used in residential and commercial applications.

3) Modified sine wave

The construction of this type of inverter is complex than simple square

wave inverter but easier compared to the pure sine wave inverter. The
output of this inverter is neither pure sine wave nor the square wave.
The output of such inverter is the some of two square waves. The
output waveform is not exactly sine wave but it resembles the shape of
a sine wave.(3)

b-inverter output phase:

(1) (2)
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(1) Single phase inverter

Single phase inverter is to convert DC inverter to AC output, single-

phase inverter is to convert the output AC voltage to single-phase, such
as AC 220V or 230V.
(2) Three phase inverter

Three phase inverter is to convert the output AC voltage for three-

phase, for example, AC 380V or 400V, three-phase electricity is
composed of three AC potentials with the same frequency, equal
amplitude, and phase difference of 120°.

C-Classification by installed use

（1）Off-grid inverter

An off-grid inverter is an inverter that converts DC power generated by

distributed power sources such as solar panels, wind turbines, etc. into
AC power, then boosts the voltage through a transformer, then selects
the maximum power point through a low-voltage DC switch (MPPT),
and finally outputs it to the grid or load.
（2）On grid inverters

A grid-connected inverter is an inverter that converts DC power

generated by distributed power sources such as solar panels, wind
turbines, etc. into AC power, then boosts the voltage through a
transformer, then selects the maximum power point through a low-
voltage DC switch (MPPT), and finally outputs it to an inverter that is
connected to the power grid.

（3）On/Off grid hybrid inverter

A hybrid inverter is an inverter that combines the functions of an off-

grid inverter and a grid-connected inverter. Hybrid inverters can be
operated either independently in solar power systems or integrated into
large power grids.

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
The main goal is to synthesize a sine wave from the DC input using
PWM techniques.

-Pulse Width Modulation (PWM)

Pulse Width Modulation (PWM) for inverters is widely used to
convert DC (Direct Current) to AC (Alternating Current) by generating
a controlled, high-quality AC output waveform. Inverters are used in
various applications like solar power systems, uninterruptible power
supplies (UPS), electric vehicle drives, and power grid interfaces. The
main goal is to synthesize a sine wave from the DC input using PWM
techniques.

-Key Concepts of PWM in Inverters:

1. Switching Mechanism:
o The DC input is switched on and off at a high frequency
(often in the kHz range) using power electronics such as
MOSFETs or IGBTs.
o The switching pattern follows a PWM scheme to create an
average output voltage that approximates a sine wave.

-The circuit responsible for configuring the switching is H-Bridge

circuit.

H-Bridge Configuration using N-Channel MOSFETs

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2. Modulated Signal:

 In a PWM inverter, the duty cycle of the switching signal is

modulated according to the desired sine wave. The high-
frequency PWM signal's average value over time resembles the
desired AC sine wave.

The averaging process in PWM

3. Filtering:
 After generating the PWM signal, a low-pass filter (usually an
inductor-capacitor filter) smooths out the rapid on-off transitions
to produce a cleaner, continuous sine wave-like AC output, then
this continuous sine wave-like AC output enters the transformer
then the transformer amplifies it to ( 220V AC).

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- Analog PWM control requires the generation of both reference and
carrier signals that feed into a comparator which creates output signals
based on the difference between the signals.

The reference signal is sinusoidal and at the frequency of the desired

output signal, while the carrier signal is often either a saw-tooth or
triangular wave at a frequency significantly greater than the reference.
When the carrier signal exceeds the reference, the comparator output
signal is at one state, and when the reference is at a higher voltage, the
output is at its second state.

This process is shown in with the triangular carrier wave in red,

sinusoidal reference wave in blue, and modulated and un-modulated
sine pulses.

Pulse Width Modulation

In order to source an output with a PWM signal, transistor or other

switching technologies are used to connect the source to the load when
the signal is high or low.

Full or half bridge configurations are common switching schemes used

in power electronics. Full bridge configurations require the use of four
switching devices and are often referred to as H-Bridges due to their
orientation with respect to a load

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- The Bubba Oscillator is a circuit that provides a filtered sine wave
of any frequency the user desires based upon the configuration of
resistors and capacitors in the circuit.

- Generating a sine wave at 50Hz requires both the reference sine wave
and a carrier wave at the switching speed of the power supply. Carrier
waves can be either sawtooth or triangular signals; in this case, a
triangular wave will be used. This wave will be at 50KHz as
determined in optimal power loss simulations. The generation of the
triangular carrier wave will be done with analog components. The
circuit for the construction of the triangle wave generator consists of a
square wave generator and integrator, as shown in Figure

Triangle Wave Generator

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

An oscillator is an electronic circuit or device that generates a

continuous, repetitive signal, usually in the form of a sine wave,
square wave, or other periodic waveform. The signal typically
oscillates between two levels (high and low), and it is used in a wide
variety of applications, from clocks and timers to communication
systems and signal processing.

Concepts of Oscillators:

1. Periodic Waveform:

 Oscillators produce a repeating signal, such as a sine wave,

square wave, or triangular wave, with a regular frequency.

2. Feedback:

 Most oscillators operate using feedback, where a portion of the

output signal is fed back into the input in a way that sustains
oscillation.

3. Frequency Control:

 The frequency of oscillation is determined by the components of

the oscillator circuit, such as resistors, capacitors, and inductors,
or through external elements like crystals (in crystal oscillators).

Types of Oscillators:
1. Linear Oscillators:

These produce sinusoidal waveforms and are often used in RF (radio

frequency) and audio applications.

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 Examples:

RC Oscillator: Uses resistors and capacitors to


determine the frequency of oscillation. Common for
generating low-frequency signals.
 LC Oscillator: Uses inductors (L) and capacitors (C)
in resonance circuits to generate high-frequency
signals.
 Crystal Oscillator: Uses a quartz crystal for highly
stable and precise frequency generation.
2. Non-Linear Oscillators:

These generate non-sinusoidal waveforms, such as square or

triangular waves, which are used in digital systems and signal
processing.

o Examples:
 Relaxation Oscillator: Generates a non-sinusoidal
waveform by charging and discharging a capacitor. It
produces waveforms like square, triangle, or saw-tooth
waves.
 As-table Multi-vibrator: A circuit that oscillates
between two states, producing a square wave.

How Oscillators Work:

 Oscillators consist of an amplifying device (like a transistor or

operational amplifier) and a feedback network.
 The feedback network provides a portion of the output signal
back to the input in the correct phase and amplitude to sustain
continuous oscillation.
 In sinusoidal oscillators, the circuit is designed to oscillate at a
specific resonant frequency, which is determined by passive
components like resistors, capacitors, or inductors, or by a crystal.

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Applications of Oscillators:

1. Clocks and Timers:

o Oscillators are essential in timing devices, providing precise
clock signals to keep time in watches, computers, and
microcontrollers.
2. Signal Generation:
o In communication systems, oscillators generate carrier
signals for transmitting and receiving radio, television, and
other communication signals.
3. Pulse Generation:
o Non-sinusoidal oscillators (e.g., square wave generators) are
used to create timing signals, clock pulses, or control signals
in digital circuits.
4. Test Equipment:
o Oscillators are used in signal generators and function
generators to produce test signals for analyzing the behavior
of electronic circuits.
5. Audio Equipment:
o Audio oscillators generate sound waves used in
synthesizers, tone generators, and other audio equipment.

Characteristics of Oscillators:

1. Frequency:
o The rate at which the oscillator completes one cycle. It is
measured in Hertz (Hz) and can range from a few Hz (in
audio oscillators) to GHz (in RF and microwave
applications).
2. Amplitude:
o The maximum value of the oscillating signal, which can be
controlled in some oscillators to produce the desired output
power.
3. Phase Noise:
o Refers to the short-term fluctuations in the oscillator's
frequency, which can degrade performance in
communication systems.
o

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 4. Stability:
o An important characteristic, especially for precision
oscillators like crystal oscillators, which must maintain a
stable frequency over time and temperature changes.

- Oscillators are crucial components in many electronic systems,

enabling precise timing, frequency generation, and signal modulation
for a wide range of applications.

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

Crystal Oscillator Definition: A crystal oscillator is defined as a

device that uses the inverse piezoelectric effect to convert vibrations
into stable oscillations.

Working Principle: The oscillator works by applying an alternating

voltage to a crystal, causing it to vibrate at its natural frequency.

Circuit Design: Crystal oscillators are designed to operate in series-

resonant mode (low impedance) or parallel-resonant mode (high
impedance).

Frequency Stability: They offer excellent frequency stability, making

them suitable for high-frequency applications.

Applications: Crystal oscillators are widely used in devices like

communication systems, GPS, and microprocessors due to their
reliability and low cost.

- In crystal oscillators, the crystal is suitably cut and mounted between

two metallic plates as shown by Figure 1a whose electrical equivalent
is shown by Figure 1b. In reality, the crystal behaves like a series RLC
circuit, formed by the components

A low-valued resistor RS
A large-valued inductor LS
A small-valued capacitor CS
which will be in parallel with the capacitance of its electrodes Cp.

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Its advantage in the inverter:
The crystal oscillator can be connected to the Bubba Oscillator to act as
a clock reference for the Bubba Oscillator. This stabilizes the
frequency of the signal of the Bubba oscillator and maintains accuracy
while reducing error and distortion.
How to connect it in the circuit:
The output of the Crystal Oscillator is connected to the input first stage
terminal of the Bubba Oscillator.

Potential Problem:

A crystal oscillator typically operates at much higher frequencies than

50 Hz. Crystal oscillators are designed to provide a very stable
frequency output, usually in the kilohertz (kHz), megahertz (MHz), or
even gigahertz (GHz) range. Common frequencies for crystal
oscillators are in the range of 32.768 kHz (often used in watches and
clocks) to several hundred MHz for communications and computing
applications.

If you need a frequency of 50 Hz, which is much lower than what

crystal oscillators provide, you can achieve this by using a frequency
divider or a phase-locked loop (PLL) circuit to divide a higher
frequency crystal oscillator down to 50 Hz.

In summary, there's no direct crystal oscillator for 50 Hz because

crystals are impractical for such low frequencies, but you can create a
50 Hz signal using a high-frequency crystal oscillator with appropriate
frequency division.

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

A Phase-Locked Loop (PLL) is a control system that generates an

output signal whose phase is related to the phase of an input signal. It is
widely used in communication systems, frequency synthesis, signal
recovery, and synchronization circuits.

Components of a PLL

1. Phase Detector (PD):

This compares the phase of the input signal (often called the
reference signal) with the phase of the output signal generated by
a voltage-controlled oscillator (VCO). It produces a signal that is
proportional to the phase difference between the two signals.
2. Low-Pass Filter (LPF):
The output of the phase detector is typically noisy, so a low-pass
filter is used to smooth this signal into a control voltage. This
control voltage is then applied to the VCO.
3. Voltage-Controlled Oscillator (VCO):
This generates a periodic signal (oscillation) whose frequency is
controlled by the input voltage. The frequency of this oscillation
is adjusted so that it locks onto the phase and frequency of the
input reference signal.
4. Feedback Loop:
The output of the VCO is fed back into the phase detector,
allowing the system to continuously adjust and maintain
synchronization with the input signal.

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PLL IC 565
The PLL IC 565 is usable over the frequency range 0.1 Hz to 500 kHz.
It has highly stable centre frequency and is able to achieve a very linear
FM detection. The output of VCO is capable of producing TTL
compatible square wave. The dual supply is in the range of ±6V to
±12V. The IC can also be operated from single supply in the range 12V
to 24V.
The following figure shows the pin-out and the internal block
schematic of PLL IC LM 565. look at datasheet(1)

Design Equations:
1. Centre Frequency (Free running freq./ output freq./oscillator freq.)
fo=0.3/(R1 C1 )
2. Lock range
fL=(8fo)/V
where V=|+V|+|-V|……..(addition of two power supplies)
3. Capture range
fc=±1/2π √((2πf_L)/(R_2 C_2 ))

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-Bubba Oscillator

The Bubba Oscillator is a circuit that provides a filtered sine wave of

any frequency the user desires based upon the configuration of resistors
and capacitors in the circuit. The circuit completes this task with four
operational amplifiers that either buffer or amplify the signal. This
oscillator is a phase shift oscillator, but unlike other phase shift
varieties that require phase shifts of 90 degrees or more, the bubba
oscillator only requires a 45 degree shift in order to function. This is

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because of the four op amps, that when placed in series, produce a total
180° shift

Bubba Oscillator Schematic

The bubba oscillator offers a few features that other oscillators cannot,
the biggest factor is that the frequency stability holds while still giving
a low distortion output. The reason for this involves the four filters that
the signal passes through, providing a clear and stable signal at point
P5, as shown in Figure

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https://www.donrowe.com/power-inverter-faq-a/258.htm(1)

https://www.amazon.( 2)
https://circuitdigest.com/tutorial/different-types-of-inverters(3)

‫ التطبيقات‬/https://techfinepv.com/introduction-different-types-of-inverters (4)

/https://www.electrical4u.com/crystal-oscillator5

https://resources.pcb.cadence.com/blog/2024-crystal-oscillator-frequency-ranges-and-
applications

| P a g e 25
/https://www.electronics-tutorial.net/analog-integrated-circuits/phase-locked-loop/pll-ic-565

https://www.keysight.com/blogs/en/tech/rfmw/2020/12/08/consider-the-source-part-1-what-is-
a-phase-lock

https://www.utmel.com/components/what-is-tl494-pwm-controller?id=943

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