a6_three phase inverter.pdf
TRANSCRIPT
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THREE PHASE INVERTER
USING ARDUINO
Project report submitted in partial fulfillment of the
requirements for the award of the degree of
BACHELOR OF TECHNOLOGY IN
ELECTRICAL AND ELECTRONICS
ENGINEERING
A. SIVA SAI 09241A02A3
A. SRI RAM 10241A0205
M. VENKATESH 10241A0232
P. RAM SREEDHAR 10241A0244
Under the guidance of
G. SWAPNA (Assistant Professor)
Department of Electrical and Electronics Engineering
GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING
& TECHNOLOGY, BACHUPALLY, HYDERABAD-72, 2014
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GOKARAJU RANGARAJU INSTITUTE OF
ENGINEERING AND TECHNOLOGY
Hyderabad, Andhra Pradesh.
DEPARTMENT OF ELECTRICAL & ELECTRONICS
ENGINEERING
CERTIFICATE:
This is to certify that the project report entitled “ THREE PHASE
INVERTER USING ARDUINO” that is being submitted by A. SIVA
SAI, A. SRI RAM, M. VENKATESH, P. RAM SREEDHAR in
partial fulfillment for the award of the Degree of Bachelor of
Technology in Electrical and Electronics Engineering to the
Jawaharlal Nehru Technological University is a record of bonafide
work carried out by him under my guidance and supervision. The
results embodied in this project report have not been submitted to
any other University or Institute for the award of any graduation
degree.
Prof. M. Chakravarthy G. Swapna
HOD, EEE ASSISTANT PROFFESSOR
GRIET, Hyderabad GRIET, Hyderabad
(GUIDE)
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Acknowledgement
This is to place on record my appreciation and deep gratitude to
the persons without whose support this project would never seen
the light of day.
I have immense pleasure in expressing my thanks and deep
sense of gratitude to my guide G. Swapna, Assistant Professor
G.R.I.E.T for her guidance throughout this project.
I also express my sincere thanks to Prof. P.M. Sarma,
Research and Development Dean for extending his help.
I express my gratitude to Prof. E.Venkateshwaralu, Project
Supervisor G.R.I.E.T for his valuable recommendations and
for accepting this project report.
Finally I express my sincere gratitude to all the members of
faculty and my friends who contributed their valuable advice
and helped to complete the project successfully.
A. SIVA SAI
A. SRI RAM
M. VENKATESH
P. RAM SREEDHAR
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Table of Contents
Abstract
List of figures Page No
Chapter I : Introduction………………………………………….…..8
Chapter II : Background ……………………………………….….9
2.1: Pulse Width Modulation Control ……………………..9
2.2: Unipolar and bipolar modulation ……………………..10
2.3: Three phase inverters ……………………………........11
Chapter III : Methodology…………………………………………..14
3.1: Three phase inverters (180° conduction)…………........14
3.2: Filter circuits configurations…………………………...16
Chapter IV : Arduino Mega…………………………………………18
4.1: overview………………………………………….........18
4.2: Summary………………………………………….........20
Chapter V: Interfacing of PS21765………………………………....26
5.1: Interfacing………………………………………………27
5.2 : 15V Power supply(Vcc)…………………………...........31
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5.3 : Three phase bridge rectifier…………………………...31
5.4 : Applications…………………………………………...33
Chapter VI: Results and Output……………………………….........34
6.1: Simulation results………………………………….........34
6.2: Conclusions……………………………………………..38
6.3: References………………………………………………38
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ABSTRACT
This project deals with study of a Sinusoidal Pulse Width Modulated Inverter
and all the parameters used to reduce the harmonics and give the good efficiency of
the inverter. The project will be commenced by a basic understanding of the circuitry
of the SPWM Inverter using arduino, the components used in its design and the
reason for choosing such components in this circuitry. Generally, only single phase
SPWM inverters are used industrially, and certain instabilities have been found in
their operation. With improper selection of system parameters, the inverter suffers
different type of instabilities and many types of harmonics. Our attempt will be to
observe the same for three phase SPWM inverter and analyze its parameters used to
get a pure sinusoidal output waveform and fewer harmonic in its output current and
voltage waveform. Three phase inverters are essential in many industrial applications
for providing adjustable-frequency power.
Arduino is an open source electronic prototyping platform based on flexible
easy to use hardware and software. It is intended for artists, designers, hobbyists and
anyone interested in creating interactive objects or environments. The effectiveness of
using arduino is that it will directly generates the required pulses for switching the full
bridge inverter effectively
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List of Figures Page No
Fig 1. Unipolar and Bipolar modulation…………………………………………...11
Fig 2. Basic Circuitry of a three phase inverter…………………………………....12
Fig 3. Pulses of 180-degree conduction…………………………………………..15
Fig 4. Output voltage in 180-degree conduction…………………………………16
Fig 5. L filter topology…………………………………………………………….16
Fig 6. L-C filter topology………………………………………………………….17
Fig 7. Arduino Mega………………………………………………………………19
Fig 8. Application Circuit of PS21765……………………………………………26
Fig 9. PS21765……………………………………………………………….…..30
Fig 10. Connection Diagram……………………………………………………...32
Fig 11. PWM signals from pin 8-13………………………………………………34-37
Fig 12. Output Voltage Waveforms……………………………………………….37
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CHAPTER I
Introduction
What if we cannot use the stored power in a battery when we don’t have power
supply? Since the energy stored in a battery is in dc form so to use this stored power
in battery we need to convert this dc form of energy to ac form. So here comes the
concept of power inverters.
The devices which can convert electrical energy of DC form into AC form is
known as power inverters. They come in all sizes and shapes, from a high power
rating to a very low power rating, from low power functions like powering a car radio
to that of backing up a building in case of power outage. Inverters can come in many
different varieties, differing in power, efficiency, price and purpose. The purpose of a
DC/AC power inverter is typically to take DC power supplied by a battery, such as a
12 volt car battery, and transform it into a 120 volt AC power source operating at 60
Hz, emulating the power available at an ordinary household electrical outlet.
DC-AC inverters have been widely used in industrial applications such as
uninterruptible power supplies, static frequency changes and AC motor drives.
Recently, the inverters are also playing important roles in renewable energy
applications as they are used to link a photovoltaic or wind system to a power grid.
Like DC-DC converters, the DC-AC inverters usually operate in a pulse width
modulated (PWM) way and switch between a few different circuit topologies, which
means that the inverter is a nonlinear, specifically piecewise smooth system. In
addition, the control strategies used in the inverters are also similar to those in DC-DC
converters. For instance, current-mode control and voltage-mode control are usually
employed in practical applications. In the last decade, studies of complex behavior in
switching power converters have gained increasingly more attention from both the
academic community and industry.
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CHAPTER II
Background
Devices that convert dc power to ac power are called inverters. The purpose of an
inverter is to change a dc input voltage to ac output voltage which will be symmetric
and will have desired magnitude and frequency. The output voltage can be varied by
varying the input dc voltage and keeping constant inverter gain, however, if the input
dc voltage is fixed and cannot be controlled, the gain of the inverter has to be varied
to obtain variable output voltage. Varying the gain of the inverter is mainly done by a
scheme which is known as Pulse Width Modulation (PWM). The inverter gain is
basically the ratio of ac output voltage to the dc input voltage.
Based on the power supply, inverters can be broadly classified into two types:
Voltage Source Inverter and Current Source Inverter. A VSI has small or negligible
impedance at its input terminal that is, it has a stiff dc voltage source, whereas for a
CSI, it is fed with adjustable current from a dc source with high impedance in this
case. For the purpose of our project, all analysis throughout this paper has been done
for Voltage Source Inverters (VSI). These can be classified into two types which are
Single Phase Inverters and Three Phase Inverters. Either type can use controllable
turn-on and turn-off devices e.g. BJTs, MOSFETs, IGBTs etc. Generally PWM
control is used to obtain ac output voltage of desired frequency and magnitude.
2.1 Pulse Width Modulation control
This is a method in which fixed dc input voltage is given to an inverter and the output
is a controlled ac voltage. This is done by adjusting the on and off periods of the
inverter components.
The advantages of PWM control are:
1. No additional components are required with this method.
2. Lower order harmonics are eliminated or minimized along with its output voltage
control. Hence, the filtering requirements are minimized since higher order harmonics
can be filtered easily.
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Different schemes of pulse-width modulation:
1. Single-pulse modulation
2. Multi-pulse modulation
3. Sinusoidal-pulse modulation
Since our project deals with Sinusoidal Pulse Width modulated Inverters, the basic
concepts of Sinusoidal PWM are explained below.
In this method of modulation, several pulses per half cycle are used and the
pulse width is a sinusoidal function of the angular position of the pulse in a cycle. A
high frequency triangular carrier wave Vc is compared with a sinusoidal reference
wave Vr of the desired frequency. The switching instants and commutation of the
modulated pulse are determined by the intersection of Vc and Vr waves. The carrier
and reference waves are mixed in a comparator. When the sinusoidal wave has higher
magnitude, the comparator output is high, else it is low. The comparator output is
processed in a trigger pulse generator in such a way that the output voltage wave has a
pulse width in agreement with the comparator pulse width.
2.2 Uni polar and bipolar modulation:
If the half-cycle sine wave modulation, the triangular carrier only in a positive or
negative polarity range of changes, the resulting SPWM wave only in a polar Range,
called unipolar control mode. If the half-cycle sine wave modulation, triangular
carrier in continuous change between positive and negative polarity, the SPWM wave
is between positive and negative changes, known as bipolar control. Unipolar and
bipolar modulations are shown in Figure.
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Fig 1: Unipolar and bipolar modulation
2.3 Three Phase Inverters:
Three phase inverters are generally used for high power applications. Three single
phase half bridge inverters are to be connected in parallel to form a three phase
inverter. The inverter is fed by a fixed dc voltage and has three phase-legs each
comprising two transistors and two diodes. With SPWM control, the controllable
switches of the inverter are controlled by comparison of a sinusoidal control signal
and a triangular switching signal. The sinusoidal control waveform determines the
desired fundamental frequency of the inverter output, while the triangular waveform
decides the switching frequency of the inverter. The ratio of the frequencies of the
triangle wave to the sinusoid is referred to as the modulation frequency ratio.
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Fig 2: Basic Circuitry of a three phase inverter
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The switches of the phase legs are controlled based on the following comparison:
V control (phase a) > V triangle, Ta+ is on
V control (phase a) < V triangle, Ta- is on
V control (phase b) > V triangle, Tb+ is on
V control (phase b) < V triangle, Tb- is on
V control (phase c) > V triangle, Tc+ is on
V control (phase c) < V triangle, Tc- is on
The gating signals of single phase inverters should be advanced or delayed by 120°
with respect to each other to get 3 phase balanced voltages. The transformer primary
winding must be isolated from each other whereas secondary winding may be
connected in wither Y or Δ.
The secondary winding of the transformer is usually connected in Δ to get rid of triple
harmonic appearing on the output voltages. Output voltages of single phase inverters
are not balanced in magnitude or phase.
A three phase output may also be obtained by a configuration of six controllable
switches and six diodes. Two types of control signals can be applied to these switches
which are 120° and 180° modes of conduction.
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CHAPTER III
Methodology
3.1 180° mode of operation:
Each transistor conducts for a period of 180°. Three of the transistors remain on at any
instant of time. When Ta+ is switched on, terminal a is connected to positive terminal
of dc input voltage. When Ta- is switched on, terminal a is brought to negative
terminal of dc input. There are six modes of operation in a cycle and duration of each
mode is 60°.
T
a
b
l
e
1
:
S
w
i
t
c
h
s
t
a
t
Three phase voltage source inverter (VSI) for 180 degree conduction
State State No. Vab Vbc Vca
Ta+, Tc- and
Tb- are on
1 VDC 0 - VDC
Tc-, Tb+ and
Ta+ are on
2 0 VDC - VDC
Tb+, Ta- and
Tc- are on
3 - VDC VDC 0
Ta-, Tc+ and
Tb+ are
on
4 -VDC 0 VDC
Tc+, Tb- and
Ta- are on
5 0 -VDC VDC
Tb-, Ta+ and
Tc+ are on
6 VDC -VDC 0
Ta+ , Tb+ and
Tc+ are on
7 0 0 0
Ta-, Tb- and
Tc- are on
8 0 0 0
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The load can be connected in either Y or Δ. Switches of any leg of the inverter
cannot be switched on at the same time since this would result in a short circuit across
the dc link voltage supply. Similarly to avoid undefined states and thus undefined ac
output line voltage, the switches of any leg of the inverter may not be switched off
simultaneously since this can result in voltages that depend on respective line current
polarity.
However, for practical applications, 180° mode of conduction is preferred
since each transistor is better utilized in case of 180° mode of conduction as compared
to 120° mode of operation for similar load conditions. Nevertheless, the analysis of
the output waveforms of the inverter will not vary much for 120° since only the
amplitude will vary for the two modes and not the vital characteristics.
This conductive angle is used in many industries. It results in six modes for
each period, considering the number of transistors, which each of them is on for a half
a period.T1, T5 andT6 transistors turn on in first half time and other transistors are
off. AC voltage is produce, by repeating the same process in the next modes. Figure. 2
shows pulses and output voltage for an ohmic load.
Fig 3. Pulses of 180-degree conduction
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Fig 4. Output voltage in 180-degree conduction
3.2: Filter circuits configurations:
The three main existing harmonic filter topologies for three-phase inverters follow.
L-Filter — First order:
Attenuation of the basic inductor filter shown in Figure 7 is –20 dB/decade over the
whole frequency range. Using this filter, the inverter switching frequency has to be
high in order to sufficiently attenuate the inverter harmonics.
Fig 5: L filter topology
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LC–Filter — Second order:
The LC-filter in Figure 8 is a second order filter Giving –40 dB/decade attenuation.
Since the previous L-filter achieves low attenuation of the inverter switching
components, a shunt element is needed to further attenuate the switching frequency
components. This shunt component must be selected to produce low reactance at the
switching frequency. But within the control frequency range, this element must
present a high magnitude impedance. A
Capacitor is used as the shunt element. The resonant frequency is calculated from.
The resonant frequency is calculated from the following equation.
f= 1/2π√LC
The LC-filter in Figure 9 has been investigated in UPS systems with a resistive load.
This LC-filter is suited to configurations where the load impedance across C is
relatively high at and above the switching frequency. The cost and the reactive power
consumption of the LC-filter are more than to the L-filter because of the addition of
the shunt element.
Fig 6: L-C filter topology
The limitation of the LC filter is that the shunt element is ineffective when
connected to a stiff grid network, where the grid impedance is insignificant at the
switching frequency. The output current ripple is the same as the inductor current
ripple with an L-filter, where the attenuation depends solely on the filter inductance.
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CHAPTER IV
Arduino Mega
4.1 Overview:
The Arduino Mega 2560 is a microcontroller board based on
the ATmega2560 (datasheet). It has 54 digital input/output pins (of which 15 can be
used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a
16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a
reset button. It contains everything needed to support the microcontroller; simply
connect it to a computer with a USB cable or power it with a AC-to-DC adapter or
battery to get started. The Mega is compatible with most shields designed for the
Arduino Duemilanove or Diecimila.
The Mega 2560 is an update to the Arduino Mega, and it has following features:
Stronger RESET circuit
Atmega 16U2 replace the 8U2
Schematic, Reference Design & Pin Mapping.
EAGLE files : arduino-mega2560_R3-reference-design.zip.
Schematic : arduino-mega2560_R3-schematic.pdf.
Pin Mapping : PinMap2560 page.
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Fig 7 : Arduino Mega
Pinout: added SDA and SCL pins that are near to the AREF pin and two other new
pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the
voltage provided from the board.In future, shields will be compatible both with the
board that use the AVR, which operate with 5V and with the Arduino Mega that
operate with 3.3V. The second one is a not connected pin, that is reserved for future
purposes.
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4.2 Summary:
Microcontroller ATmega2560
Operating Voltage : 5V
Input Voltage (recommended) : 7-12V
Input Voltage (limits) : 6-20V
Digital I/O Pins : 54 (of which 15 provide PWM o/p)
Analog Input Pins : 16
DC Current per I/O Pin : 40 mA
DC Current for 3.3V Pin : 50 mA
Flash Memory : 256 KB of which 8 KB used by
bootloader
SRAM : 8 KB
EEPROM : 4 KB
Clock Speed : 16 MHz
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4.3 Power:
The Arduino Mega can be powered via the USB connection or with an external power
supply. The power source is selected automatically.
External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or
battery. The adapter can be connected by plugging a 2.1mm center-positive plug into
the board's power jack. Leads from a battery can be inserted in the Gnd and Vin pin
headers of the POWER connector.
The board can operate on an external supply of 6 to 20 volts. If supplied with less than
7V, however, the 5V pin may supply less than five volts and the board may be
unstable. If using more than 12V, the voltage regulator may overheat and damage the
board. The recommended range is 7 to 12 volts.
The power pins are as follows:
VIN. The input voltage to the Arduino board when it's using an external power source
(as opposed to 5 volts from the USB connection or other regulated power source).
You can supply voltage through this pin, or, if supplying voltage via the power jack,
access it through this pin.
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be
supplied with power either from the DC power jack (7 - 12V), the USB connector
(5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins
bypasses the regulator, and can damage your board. We don't advise it.
3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw
is 50 mA.
GND. Ground pins.
4.4 Memory:
The ATmega2560 has 256 KB of flash memory for storing code (of which 8 KB is
used for the bootloader), 8 KB of SRAM and 4 KB of EEPROM (which can be read
and written with the EEPROM library).
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4.5 Input and Output:
Each of the 54 digital pins on the Mega can be used as an input or output, using
pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each
pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor
(disconnected by default) of 20-50 kOhms. In addition, some pins have specialized
functions:
Serial: 0 (RX) and 1 (TX); Serial 1: 19 (RX) and 18 (TX); Serial 2: 17 (RX) and 16
(TX); Serial 3: 15 (RX) and 14 (TX). Used to receive (RX) and transmit (TX) TTL
serial data. Pins 0 and 1 are also connected to the corresponding pins of the
ATmega16U2 USB-to-TTL Serial chip.
External Interrupts: 2 (interrupt 0), 3 (interrupt 1), 18 (interrupt 5), 19 (interrupt 4),
20 (interrupt 3), and 21 (interrupt 2). These pins can be configured to trigger an
interrupt on a low value, a rising or falling edge, or a change in value. See the
attachInterrupt() function for details.
PWM: 2 to 13 and 44 to 46. Provide 8-bit PWM output with the analogWrite()
function.
SPI: 50 (MISO), 51 (MOSI), 52 (SCK), 53 (SS). These pins support SPI
communication using the SPI library. The SPI pins are also broken out on the ICSP
header, which is physically compatible with the Uno, Duemilanove and Diecimila.
LED: 13 There is a built-in LED connected to digital pin 13. When the pin is HIGH
value, the LED is on, when the pin is LOW, it's off.
TWI: 20 (SDA) and 21 (SCL). Support TWI communication using the Wire library.
Note that these pins are not in the same location as the TWI pins on the Duemilanove
or Diecimila.
The Mega2560 has 16 analog inputs, each of which provide 10 bits of resolution (i.e.
1024 different values). By default they measure from ground to 5 volts, though is it
possible to change the upper end of their range using the AREF pin and
analogReference() function.
There are a couple of other pins on the board:
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AREF : Reference voltage for the analog inputs. Used with analogReference().
Reset : Bring this line LOW to reset the microcontroller. Typically used to add a
reset button to shields which block the one on the board.
4.6 Communication:
The Arduino Mega2560 has a number of facilities for communicating with a
computer, another Arduino, or other microcontrollers. The ATmega2560 provides
four hardware UARTs for TTL (5V) serial communication. An ATmega16U2
(ATmega 8U2 on the revision 1 and revision 2 boards) on the board channels one of
these over USB and provides a virtual com port to software on the computer
(Windows machines will need a .inf file, but OSX and Linux machines will recognize
the board as a COM port automatically. The Arduino software includes a serial
monitor which allows simple textual data to be sent to and from the board. The RX
and TX LEDs on the board will flash when data is being transmitted via the
ATmega8U2/ATmega16U2 chip and USB connection to the computer (but not for
serial communication on pins 0 and 1).
A SoftwareSerial library allows for serial communication on any of the Mega2560's
digital pins.
The ATmega2560 also supports TWI and SPI communication. The Arduino software
includes a Wire library to simplify use of the TWI bus; see the documentation for
details. For SPI communication, use the SPI library.
4.7 Programming:
The Arduino Mega can be programmed with the Arduino software (download). For
details, see the reference and tutorials.
The ATmega2560 on the Arduino Mega comes preburned with a bootloader that
allows you to upload new code to it without the use of an external hardware
programmer. It communicates using the original STK500 protocol (reference, C
header files).
You can also bypass the bootloader and program the microcontroller through the
ICSP (In-Circuit Serial Programming) header; see these instructions for details.
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The ATmega16U2 (or 8U2 in the rev1 and rev2 boards) firmware source code is
available in the Arduino repository. The ATmega16U2/8U2 is loaded with a DFU
bootloader, which can be activated by:
On Rev1 boards: connecting the solder jumper on the back of the board (near the map
of Italy) and then resetting the 8U2.
On Rev2 or later boards: there is a resistor that pulling the 8U2/16U2 HWB line to
ground, making it easier to put into DFU mode. You can then use Atmel's FLIP
software (Windows) or the DFU programmer (Mac OS X and Linux) to load a new
firmware. Or you can use the ISP header with an external programmer (overwriting
the DFU bootloader). See this user-contributed tutorial for more information.
4.8 Automatic (Software) Reset:
Rather then requiring a physical press of the reset button before an upload, the
Arduino Mega2560 is designed in a way that allows it to be reset by software running
on a connected computer. One of the hardware flow control lines (DTR) of the
ATmega8U2 is connected to the reset line of the ATmega2560 via a 100 nanofarad
capacitor. When this line is asserted (taken low), the reset line drops long enough to
reset the chip. The Arduino software uses this capability to allow you to upload code
by simply pressing the upload button in the Arduino environment. This means that the
bootloader can have a shorter timeout, as the lowering of DTR can be well-
coordinated with the start of the upload.
This setup has other implications. When the Mega2560 is connected to either a
computer running Mac OS X or Linux, it resets each time a connection is made to it
from software (via USB). For the following half-second or so, the bootloader is
running on the Mega2560. While it is programmed to ignore malformed data (i.e.
anything besides an upload of new code), it will intercept the first few bytes of data
sent to the board after a connection is opened. If a sketch running on the board
receives one-time configuration or other data when it first starts, make sure that the
software with which it communicates waits a second after opening the connection and
before sending this data.
The Mega2560 contains a trace that can be cut to disable the auto-reset. The pads on
either side of the trace can be soldered together to re-enable it. It's labeled "RESET-
25
EN". You may also be able to disable the auto-reset by connecting a 110 ohm resistor
from 5V to the reset line; see this forum thread for details.
26
CHAPTER V
INTERFACING OF PS21765
PS21765 is a 600V, 20 Ampere short pin DIP Intelligent Power Module.
Fig 8 : Application Circuit of PS21765
1) Input drive is active-high type. There is a 2.5k(min.) pull-down resistor integrated
in the IC input circuit. To prevent malfunction, the wiring of each input should be as
short as possible. When using RC coupling circuit, make sure the input signal level
meets the turn-on and turn-off threshold voltage. See application notes for details.
2) Internal HVIC provides high voltage level shifting allowing direct connection of
all six driving signals to the controller.
27
3) FO output is an open collector type. Pull up resistor (R3) should be adjusted to
current sink capability of the controller.
4) To prevent input signal oscillations, minimize wire length to controller (~2cm).
Additional RC filtering (C5 etc.) may be required. If filtering is added be careful to
maintain proper dead time and voltage levels. See application notes for details.
5) All capacitors should be mounted as close to the terminals as possible. (C1: good
temperature, frequency characteristic electrolytic type, and C2, C3: good temperature,
frequency and DC bias characteristic ceramic type are recommended.)
6) Shows short circuit protection disabled. See application notes for use of short
circuit protection.
7) Local decoupling frequency filter capacitors must be connected as close as possible
to the module’s pins.
8) The length of the DC link wiring between C5, C6, the DIP’s P terminal and the
shunt must be minimized to prevent excessive transient voltages. In particular C6
should be mounted as close to the DIP as possible.
9) Use high quality, tight tolerance current sensing resistor. Connect resistor as close
as possible to the DIP’s N terminal. Be careful to check for proper power rating. See
application notes for calculation of resistance value.
10) Inserting a Zener diode (24V/1W) between each pair of control supply terminals
to prevent surge destruction is recommended.
5.1: Interfacing:
The PWM pulses required for the switching mode of the inverter are
generated using arduino software program illustrated below:
Program:
#include<GraphSeries.h>
GraphSeries pin8 = GraphSeries("Pin 8");
GraphSeries pin9 = GraphSeries("Pin 9");
GraphSeries pin10 = GraphSeries("Pin 10");
GraphSeries pin11 = GraphSeries("Pin 11");
GraphSeries pin12 = GraphSeries("Pin 12");
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GraphSeries pin13 = GraphSeries("Pin 13");
GraphSeries input= GraphSeries("input voltage");
void setup()
{
pinMode(8,OUTPUT);
pinMode(9,OUTPUT);
pinMode(10,OUTPUT);
pinMode(11,OUTPUT);
pinMode(12,OUTPUT);
pinMode(13,OUTPUT);
Serial.begin(9600);
}
void loop() {
double d = 3.333;
// 180 degree conduction mode - s1:0-180,s2:60-240,s3:120-300,s4:180-360,s5:240-
60,s6:300-120
digitalWrite(8,HIGH);
delay(d);
pin8.SendData(2);
digitalWrite(12,LOW);
digitalWrite(9,HIGH);
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delay(d);
pin9.SendData(3);
digitalWrite(13,LOW);
digitalWrite(10,HIGH);
delay(d);
pin10.SendData(4);
digitalWrite(8,LOW);
digitalWrite(11,HIGH);
delay(d);
pin11.SendData(5);
digitalWrite(9,LOW);
digitalWrite(12,HIGH);
delay(d);
pin12.SendData(6);
digitalWrite(10,LOW);
digitalWrite(13,HIGH);
delay(d);
pin13.SendData(7);
digitalWrite(11,LOW);
}
The above program generates the gate pulses in which each switch conducts
for a period of 60 degrees following 180 degree conduction mode.
This inverter kit is designed in our college and it consists of the following circuits
which are mounted on it.
30
Fig 9. PS21765
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5.2: 15V POWER SUPPLY (Vcc):
The 15v DC level required for PS21765 is taken from a rectifier circuit using voltage
regulator LM7815.
5.3: THREE PHASE DIODE BRIDGE RECTIFIER:
The DC input to the inverter is taken from a three phase diode bridge rectifier
comprising of 6 power diodes connected in full bride rectifier mode.
32
Fig 9 : Connection Diagram
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ARDUINO PINS
PS 21765 PINS
8 S1
9 S2
10 S3
11 S4
12 S5
13 S6
GND GND
3.3V 3.3V
Table 2 : Connections of Arduino to PS21765
The interconnections between the arduino mega and the PS21765 were connected as
illustrated above.
5.4: APPLICATIONS:
Refrigerators
Air Conditioners
Small Servo Motors
Small Motor Control
Solar panels
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CHAPTER VI
RESULTS AND OUTPUT
Input of 26V is taken from the diode bridge rectifier and is applied to the inverter, the
following results were obtained during simulation process.
6.1: Simulation result
PWM Signal going to pin 8:
35
PWM Signal going to pin 9:
PWM Signal going to pin 10:
36
PWM Signal going to pin 11:
PWM Signal going to pin 12:
37
PWM Signal going to pin 13:
OUTPUT:
Output Voltage R-Phase
38
Output VoltageY-Phase
39
Output Voltage B-Phase
40
6.2: Conclusions:
Pulse width modulated (PWM) inverters, can provide higher quality of output voltage.
The PWM inverter may be a preferred choice on account of its simplicity and low
cost. The switch control circuit is very simple and the switching frequency is
significantly lower. This results in low switching losses.
6.3: References:
1. Bhimbra P.S., “Power Electronics”, Khanna Publishers, 4th edition
2. Chattopadhyay and Rakshit P.C., “Electronics, Fundamentals and Applications”,
New Age International P Limited, Publishers, 2007
3. Arduino Mega Reference – “arduino.cc”.
4. PS21765 Application note.