single phase induction motor speed control
DESCRIPTION
Single phase induction motor speed control ,,,,TRANSCRIPT
SINGLE PHASE INDUCTION MOTOR SPEED CONTROL
BY V/F METHOD THROUGH
MICROCONTROLLER
GUIDED BY: SUBMITTED BY:Shri M.P.S. CHAWLA VIPIN GUPTAAssoc. Professor M.E. (Power Electronics)Electrical Deppt., Sgsits-Indore
Introduction
Speed control was used in DC motor’s because of constant
speed operation at all load and simple controller design
but it was inefficient and required high maintenance.
Now, Due to the advancement in microcontroller and
power electronics; Induction motors are being used in
greater numbers throughout a wide variety of domestic
and commercial applications because it provides many
benefits and reliable device to convert the electrical
energy into mechanical motion.
Continue…….
Because of the only availability of single
phase power for the domestic purpose. So,
here we implemented a single phase motor
speed control hardware to control various
appliances such as washing machines, fans,
hand-held power tools and induction motor-
based centrifugal pump.
Literature Survey literature study is performed about various
methods of controlling the speed of the single
phase induction motor and come to the
conclusion that the best solution is using a PSC
(permanent slip capacitor) motor with three-
phase inverter bridge.
This system allows varying the induction motors
speed, varying the frequency and voltage.
It was made implementing PWM (Pulse Width
Modulation) control algorithms in a PIC
microcontroller.
Microcontroller output signals are sent to the IGBTs
driver and finally to the IGBTs, where DC bus
(generated by a rectifier) is synthesized to provide
two Sinusoidal voltages at 90 degrees out of phase
with varying amplitude and varying frequency to
fed the motor, according to the V/f profile.
Continue…….
Speed Control Of Induction Motor
The speed of an Induction Motor is given as
follows
N = 120 f / P
The torque equation of the induction motor
can be expressed as follows
T = [(k2f2)/(R′r/s)2+(ωL′lr)2 ]*R′r/Sω
Various Speed Control Techniques
Pole changing
Stator voltage control
Rotor resistance control
Stator frequency control
V/F constant control
V/F Method Of Speed Control
In this mode of operation, the voltage across the
magnetizing inductance in the ’exact’ equivalent circuit
reduces in amplitude with reduction in frequency
Smooth variation of voltage and frequency of the AC
output
The current through the inductance and the flux in the
machine remains constant
Torque-speed Curves With V/F Held Constant
SPIM Requirements
Voltage ratio Vaux/Vmain is approximately equal
to the effective turns ratio a, Naux/Nmain(»1.37
for the motor used for this project)
Current ratio is Iaux/Imain=1/a Vaux leads Vmain
by 90º at rated frequency
Constant V/Hz (voltage frequency ratio) for
adjustable speed control
Configuration Of SPIM Drive
Circuit Topology Of Drive
RECTIFIER
INVERTER
MICROCONTROLLER CONTROL CIRCUIT INPUT
Pulse Width Modulation To digitalize the power
To produce the desired RMS output
Triangle wave is used as carrier and reference signal is
sinusoidal wave, whose frequency is the desired
frequency
To produce the desired fundamental component of
frequency
PWM AND FREQUENCY SPECTRUM
Problem Formulation
Input section is replaced with a standard diode
bridge rectifier
Output section has a 3-phase inverter bridge
One end of the main winding and start windings
are connected to one half bridge each, The other
are tied together and connected to the third half
bridge
Circuit Diagram
PIC16F72 Microcontroller To control 3-phase inverter bridge
Generate PWM frequency approximately 8 KHz
Timer1 (1:4 prescale) is counted up from 00 to 634
Gives a dead time of one micro second when the
microcontroller is running at 20 MHz
PORT C <0:5> are initialized to output PWMs
Continue……… A/D channels are initialized to read frequency reference (AN1)
-Frequency reference is read using a potentiometer connected to
A/D channel 1.
Timer0 is used for setting the motor frequency based on the
potentiometer setting
The sine table is loaded into RAM
Timer0 overflow, Timer1 overflow and INT interrupts are enabled
PIC16F72 Pin Description
Microcontroller Limitation Generating software PWM takes significant processing
power. This limits any other application that may be
required to run on the same MCU
The safe PWM frequency range is from 6 khz to 10 kHz
with an operating frequency of 20 Mhz. The PWM cycle
may have an error up to ±5%.
The resolution is also limited between 6 to 8 bits. In
addition to this, generating PWM outputs in firmware uses
the on-chip Timer, program and data memory.
Driver IRAMS10UP60A Integrated Gate Drivers and Bootstrap Diodes
Temperature Monitor
Temperature and Over current shut down
Fully Isolated Package
Low VCE (on) Non Punch Through IGBT Technology
Under-voltage lockout for channels
Continue……..Matched propagation delay for all channels
Low side IGBT emitter pins for current control
Schmitt-triggered input logic
Cross-conduction prevention logic
Lower di/dt gate driver for better noise immunity
Internal Electrical Sechmatic-IRAMS10UP60A
Printed Circuit Board Designing
Eagle PCB layout editor 6.1.0 is used
Developed the schematic of the circuit
Convert it’s schematic into board which is required PCB layout
Schematic of Circuit
PCB Layout
Power Supply5 V DC supply for microcontroller
15 V DC supply for Driver Power Module- IRAMS10UP60A
30 V Isolated power Supply for generate the results
CodingCoding is done in Assembly
language
MP Lab assembler is used for the simulation
MP Lab assembler is also used for generating of Hex file of the code
Results
Auxiliary and Main winding voltage respectively at 25 Hz
Auxiliary and Main winding voltage respectively at 40 Hz
Auxiliary and Main winding voltage respectively at 60 Hz
Implemented Hardware
Discussion & Conclusion It is the single-phase induction motor
that makes the less noise.
Excellent for applications with high on/off cycle rates.
Most reliable of the single-phase motors.
The best choice for variable speed control.
Scope & Future Work In addition, a 3-phase induction motor can
be controlled using the firmware
Gives flexibility to the system without changing hardware
We can protect the hardware by adding over current, over voltage and over temperature peripheral circuitry and complex software programming.