Electrolytic Capacitor Less Motor Drives of AC/DC Conversion with Speed Control and Power Factor Control used Auto Feedback Technique

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  • Total Downloads : 75
  • Authors : Sudharsan S, Maruthasalam M, Tamilselven N, Uthayakumar M, Mrs. Chandra Prabha R
  • Paper ID : IJERTCONV7IS06016
  • Volume & Issue : ETEDM
  • Published (First Online): 18-05-2019
  • ISSN (Online) : 2278-0181
  • Publisher Name : IJERT
  • License: Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 International License

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Electrolytic Capacitor Less Motor Drives of AC/DC Conversion with Speed Control and Power Factor Control used Auto Feedback Technique

Sudharsan S Maruthasalam M

UG student UG student

Department of Electrical and Electronics Engineering Department of Electrical and Electronics Engineering SCAD Institute of technology SCAD Institute of technology

Tamilselven N Uthayakumar M

UG student UG student

Department of Electrical and Electronics Engineering Department of Electrical and Electronics Engineering SCAD Institute of technology SCAD Institute of technology

Mrs. Chandra Prabha R

Asst professor

Department of Electrical and Electronics Engineering SCAD Institute of technology

Abstract:- This system will help us to develop the power factor and the reactive power flow in a system. Hence, we can control power loss and unusual power rating in transmission lines. We also provide a manual selection of a power factor correction with auto adjustable correction methods, which will correct and adjust the values automatically .This concept has been developed for applications such as hybrid electric power trains. Specifically, this topology allows different DC-link voltages to drive a traction motor using the battery voltage as one of the voltage levels.

Keywords: Atmel 8051 microcontroller, fly-back converter, transformer, encoder and decoder, bldc motor.


There are always some researches going on the topic such as power factor correction and power factor improvement with several methods.

Here is one like that we proposed, here we use fly-back converter method to determine the current and the voltage across the load. We also provide an automated feedback with intelligent control schema. This is capable of converting the pulse to a desired level according to the output load (current).

We also provide the system with a capacitor less one because the capacitor induces the leading power factor. Hence, we can control the loads with the pre-determined values and a fixed power factor. The power factor is maintained at approx. on 0.98.


A fly-back converter transforms a DC voltage at the input to a DC voltage at the output. The operating principle is similar to the buck-boost converter, but an additional transformer is used to achieve galvanic isolation of the input and output.

For a fly-back converter in continuous conduction mode the output voltage across resistor R is given by:

Where D is the duty cycle, and N1 and N2 are the turns numbers of the primary and secondary windings.


When the current flowing through an inductor is cut off, the energy stored inthe magnetic field is released by a sudden reversal of the terminal voltage. If a diode is in place to conduct the stored energy somewhere useful, the diode is called a fly-back diode. This only requires one winding on the inductor, so the inductor would be called a fly-back transformer. This arrangement has the

interesting property of transferring energy to the secondary side of the power supply only when the primary switch is off.

The basic fly-back converter uses a relatively small number of components. A switching device chops the input DC voltage and the energy in the primary is transferred to the secondary through the switching transformer. A diode in the secondary rectifies the voltage while the capacitor smoothes the rectified voltage. In a practical circuit, a feedback circuit is used to monitor the output voltage and while a control circuit switching device.



Bridge Fly-back




Rectifier Vgs


Output Voltage converter


Atmel 8051


While a potentiometer allows for control of the fly-back converter output during operation, it is unable to hold a constant output with a variable input that changes. This is used in the majority of fly-back converter applications which require automation to correct an input voltage. The simplest way to maintain a constant output is to use a feedback loop that will change the output automatically instead of by manual control (using visual feedback from a voltmeter). The feedback loop should be able to increase the duty cycle to raise the output when the output is too low and decrease it when the output is too high. To do this, the output will need to be compared to a reference voltage which remains constant even if the input changes. The error between the

output and the reference voltage is then amplified and added to a set bias voltage. The resulting voltage is then used as the control voltage for PWM. When the output is too low, the amplified error increases which causes the control voltage to increase. The increase in control voltage increases the duty cycle until the output is correct. When the output is too high, the amplified error becomes negative which decreases the duty cycle to correct output.

Both of these scenarios work together to constantly make slight adjustments to the duty cycle so that the output remains stable. The simulations for feedback show how the output changes with the gain of the amplifier

Power Factor Correction (PFC) Continuous Conduction Mode Fly-back Converter

%This example shows how to correct the power factor using a PFC

%p reconverted. This technique is useful when non-linear impedances, such ass

%Switch Mode Power Supplies are connected to an AC grid. As the current

%flowing through the inductor is never zero during the switching cycle, the

%boost converter operates in Continuous Conduction Mode (CCM). The inductor

%current and the output voltage profiles are controlled using simple

%integral control. During startup, the reference output voltage is ramped

%up to the desired voltage.


clc; clear all;


Line_Voltage_Peak = 120*sqrt(2); % Input Voltage Peak to the Full Bridge Rectifier f_line = 60; % Power line frequency [Hz] Voref = 400; % Desired Output Voltage from PFC Preconverter Power = 1e3; % Maximum steady state power capability [W] R = 200; % Arbitrary resistive load [Ohms]

del_V = 10; % Peak-Peak Output Voltage Ripple [V] IndCurrRipple = 8; % Inductor Current Ripple [%]

Conv_efficiency = 92; % Nominal efficiency of the preconverter [%] f_sw = 50e3; % MOSFET Switching Frequency [Hz] Ts = 1/(100*f_sw); % Sampling time for the plant [sec]

Tsc = 1/(50*f_sw); % Sampling time for the controller [sec]

t_holdup = 16.6e-3; % Minimum hold up time for a minimum output I_Kp = 0.15; % Proportional Gain of the Inner Current Loop I_Ki = 15; % Integral Gain of the Inner Current Loop V_Kp = 0.01; % Proportional Gain of the Outer Voltage Loop V_Ki

= 10; % Integral Gain of the Outer Voltage Loop


Duty = (Voref-Line_Voltage_Peak)/Voref;

I_in_peakmax = 2*(Power/(Conv_efficiency*0.01))/Line_Voltage_Peak;


del_I = (IndCurrRipple/100)*I_in_peakmax; L = (Line_Voltage_Peak*Duty)/(f_sw*del_I); 1

Filter Capacitance

C = max((2*Power*t_holdup)/((Voref)^2- 340^2),Power/(2*pi*f_line*del_V*Voref));


Experimental waveforms of vi, ii, vCa, and io with Ca =10 F

a vi, ii, and io (vi: 200 V/div., ii: 0.5 A/div., io: 1 A/div., 2 ms/div.) b vCa and io (vCa: 50 V/div., io: 1 A/div., 2 ms/div.


output power waveform

Output current waveform

Line current & line voltage

Line voltage

reference current & inductance curren

Input voltage

Output voltage

Rectification voltage


Most battery operated circuits require ac-dc conversion to maintain full operation. In most circumstances that require stepping up and down the input voltage, fly-back converters are worth the price of the extra inductor and capacitor for the efficiency and stable operation they provide. While this project does go into detail about simulation results for the fly-back converter, the physical potentiometer controlled fly-back converter built was unsuccessful. Additionally, a cost benefit analysis to determine peak efficiency with the cheapest cost for the inductors and capacitors was never done. These are both things that could have been done with extra time and group members. From this project, one learns ac-dc converter optimization and control.


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