International Conference on Current Research in Engineering Science and Technology (ICCREST-2016)

E-ISSN :2348 - 8549 www.internationaljournalssrg.org Page 7

HARDWARE IMPLEMENTATION OF PERTURB AND OBSERVE ALGORITHM BASED ON AN ELECTRICAL ENERGY

CONVERSION SYSTEM M.Murugesan1, R.Aruna2

1PG Student, P.S.R. Engineering College, India

2Assistant Professor, P.S.R. Engineering College, India

Abstract – The design of perturb and observe algorithm based on an electrical energy conversion system is presented here. An electrical energy conversion system consists of uncontrolled diode bridge rectifier, a dc-to-dc boost converter and a voltage source inverter. If the rectified voltages are varied, the output of boost converter and inverter also varied. But we need constant ac output load voltage, which can be achieved by controlling the boost converter using perturb and observe algorithm. This algorithm is programmed by embedded C language which can be fetched in the PIC microcontroller 16F877A. This algorithm controls the gate pulses in the boost converter, based on the output of rectifier to get a constant output load voltage. This experimental result indicates the constant output voltage at different source voltages which can be developed and tested successfully in laboratory.

Keywords: Electrical Energy Conversion System, Perturb and Observe Algorithm, Embedded C program language.

I. INTRODUCTION An electrical energy conversion system is the system, which converts the energy from AC-DC-AC to the load. The source of an ac voltage can be taken from the plug point 230V ac supply which is converted into 24V ac supply by means of step down transformer. This 24V ac supply is given to the regulated power supply (RPS) which gives 24V dc supply. Using variable resistor we can vary that voltage from 6V to 18V by manual. This variation gives the variable output load voltage which can be controlled by microcontroller using Perturb and Observe algorithm. This algorithm indicates if input voltage is maximum, it will reduce the duty cycle to the boost converter and if input voltage is minimum, it will increase the duty cycle to the boost converter. Therefore the output of load voltage gets constant by means of this algorithm. The algorithm is programmed by embedded C language fetched in the PIC microcontroller 16F877A. The overall functional block diagram of Perturb and Observe method based an electrical energy conversion system block diagram is shown in figure 1.

Fig. 1. Block diagram of an electrical energy conversion system using P&O method.

II. DESIGN OF REGULATED POWER SUPPLY

The design of regulated power supply which consists of diodes, capacitors, voltage regulator and resistor. Initially the 24V ac voltage is converted into 24V dc voltage by using diodes then the ripple content of this 24V dc voltage can be filtered by using capacitors. The output voltage of capacitor can be regulated into 5V dc supply by using voltage regulators and again we filtered the regulated voltage by capacitor to the resistor. The overall design of regulated power supply is shown in figure 2.

Fig. 2. Design of regulated power supply.

International Conference on Current Research in Engineering Science and Technology (ICCREST-2016)

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III.DESIGN OF BOOST CONVERTER

A boost converter (step-up converter) is a power converter with an output DC voltage greater than its input DC voltage. It is a class of switching-mode power supply (SMPS) containing at least two semiconductor switches (a diode and a transistor or a MOSFET or an IGBT or a BJT) and at least one energy storage element. A process that changes one DC voltage to a different DC voltage is called DC to DC conversion. A boost converter is a DC to DC converter with an output voltage greater than the source voltage is shown in Fig. 3.

Fig. 3. Boost converter

A boost converter is sometimes called a step-up

converter since it steps up the source voltage. The output voltage of the boost converter is given by

0

i n

V 1=V ( 1 - d )

Vin = input voltage of boost converter Vo = output voltage of boost converter d = duty cycle

The design of boost converter is shown in figure 4.

Fig. 4. Design of boost converter

IV.PERTURB AND OBSERVE METHOD The P&O algorithm are widely used in control of gate signal to the boost converter. As the name implies, the concept behind of this method is based on observation of uncontrolled diode bridge rectifier output voltage and its perturbation by changing the voltage of rectifier operation. The algorithm increments or decrements continuously the reference voltage based on the previous value until reaches the constant output voltage.

The flowchart implementation of P&O method is given in Fig. 5.

Fig. 5. Flowchart of P&O method

The direction of perturbation of output voltage with respect to power as shown in table 1.

Table 1. The direction of perturbation of voltage with respect to power.

Sign of ΔV Sign of ΔP Duty cycle

+ + +D

- - +D

+ - -D

- + -D

The perturb and observe method based embedded C program is fetched in PIC microcontroller 16F877A. PIC16F873A/876A devices are available only in 28-pin packages, while PIC16F874A/877A devices are available in 40-pin and 44-pin packages.

V. VOLTAGE SOURCE INVERTER An inverter is a circuit that converts DC to AC. Pulse

Width Modulation (PWM) is a switching technique that is used to decrease the total harmonic distortion in the inverter circuit. The output of the boost converter is fed to a voltage source inverter which converts the constant DC to constant AC having a frequency of 50 Hz. The objective in pulse-width modulated single-phase inverters is to shape and control the single-phase output voltages in magnitude and frequency with an essentially constant input voltage Vo.

International Conference on Current Research in Engineering Science and Technology (ICCREST-2016)

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The schematic diagram of a voltage source inverter is shown in Fig. 6.

Fig. 6. Voltage source inverter.

The design of voltage source inverter is shown in figure 7.

Fig. 7. Design of voltage source inverter

VI. OPTO COUPLER Opto coupler is an LED is a light emitting device and photo transistor is a light sensitive device. The conduction current of phototransistor can be controlled via the conduction current of the LED, even though the two devices are physically separated. Such a package is known as an opto coupler, since the input (LED) and the output (phototransistor) devices are optically coupled. The most important point to note about the opto coupler device is that a circuit connected to its input can be electrically fully isolated from the output circuit and that a potential difference of hundreds (or) thousands of volts can safely exist between these two circuits without adversely influencing the opto coupler action. This isolating characteristic is the main attraction of this type of Opto coupler device, which is generally known as an isolating Opto coupler. The schematic diagram of opto coupler is shown in figure 8.

Fig 8.Schematic diagram of optocoupler.

VII. HARDWARE CIRCUIT DIAGRAM

Hardware circuit diagram of perturb and observe algorithm based an electrical system is shown in figure 9.

Fig 9.Hardware circuit diagram of perturb and observe algorithm based on an electrical energy conversion system.

VIII.EXPERIMENTAL RESULTS

This experimental result indicates the constant output voltage at different source voltages which can be developed and tested successfully in laboratory. The hardware design of perturb and observe algorithm based on an electrical energy conversion system are shown in figure 10.

Fig 10.Hardware design of perturb and observe algorithm based on an electrical energy conversion system

The output waveform of perturb and observe algorithm based on an electrical energy conversion system is shown in below.

For 18V input ac supply, the corresponding 42V of an output is shown in figure 11.

Fig 11 (a).18V input ac voltage.

International Conference on Current Research in Engineering Science and Technology (ICCREST-2016)

E-ISSN :2348 - 8549 www.internationaljournalssrg.org Page 10

Fig 11(b).42V output ac voltage.

For 6V input ac supply, the corresponding 42V of an output is shown in figure 12.

Fig 12(a).6V input ac voltage.

Fig 12(b).42V output ac voltage.

IX.CONCLUSION

From this paper, perturb and observe algorithm based on an electrical energy conversion system have been presented and designed for constant output load voltage with variable input voltages. In this algorithm, we can easily control the boost converter to get a constant output load voltage. The converters being used not only the operations have been smoothened but also the efficiency has been increased to a great extent. The system result indicates the constant output voltage at different source voltages which can be developed and tested successfully in laboratory.

X.REFERENCES

1. Mohammad H. Rashid. Power electronics-circuit. Devices and application. 3rd ed; 2004. 2.Kassakian J,Schlecht M, Verghese G(1991) Principles of power electronics. 3.Batarseh I(2004) Power electronics-circuit wiley, Newyork. 4.Mohan N, Undeland T, Robbins W (2003) power electronics: Converters, applications and design. wiley, Newyork. 5. Mohammad Ali Mazidi, Rolin McKinlay, Danny Causey Microcontroller and embedded systems using assembly and c language released 2008. 6.Han-Way Huang An Introduction to software and hardware interfacing released 2013.