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A MODIFIED CLOSED LOOP CONTROL OF HIGH STATIC GAIN

SEPIC CONVERTER WITH MAGNETIC COUPLING

FOR RENEWABLE APPLICATIONS

BATCH MEMBERS: MURALI KRISHNAN L (312811105021) VIGNESH R (312811105047) VIGNESH V (312811105048)GUIDED BY Mr.D JOHN SUNDAR (AP/EEE)

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PRESENTATION OUTLINE ABSTRACT OBJECTIVE MOTIVATION PROBLEM STATEMENT LITERATURE REVIEW BLOCK DIAGRAM SIMULATION CIRCUIT DESCRIPTION OF HYBRID PSAGSO ALGORITHM WAVEFORMS HARDWARE CIRCUITS RESULTS CONCLUSION

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ABSTRACTA high static gain step-up dc–dc converters based on the modifiedSEPIC Converter is presented in this paper. The proposed topologies present low switch voltage and high efficiency for low input voltage and high output voltage applications. The configurations with magnetic coupling is presented and analyzed. The magnetic coupling allows the increase of the static gain maintaining a reduced switch voltage. The experimental prototypes were developed with an input voltage equal to 15 V and an output power equal to 100 W. The efficiency at nominal power obtained with the prototype without magnetic coupling was equal to 91.9% with an output voltage of150V and with magnetic coupling operating with an output voltage equal to 300 V, presents efficiency equal to 92.2%.

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OBJECTIVE

To design a closed loop high static gain step-up DC-DC

converter with magnetic coupling based on the modified

SEPIC converter .

To present a topology with low switch voltage and high

efficiency for low input voltage and high output voltage

applications.

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MOTIVATION Electricity demand is the major concern in the world

today. To meet the demand the number of natural sources comes

under electricity production. Among those sources solar energy is considered as it is

most readily available and free source of energy since prehistoric times.

It is estimated that solar energy equivalent to over 15,000 times the world's annual commercial energy consumption reaches the earth every year.

Single ended primary inductor with solar energy is considered for the improvement of power generation.

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PROBLEM STATEMENT

In SEPIC converter the voltage at its output to be greater

than, less than or equal to that its input, whereas in high

static gain SEPIC converter the output voltage is higher

than its input voltage.

The magnetic coupling allows the increase of static gain

maintaining a reduced switch voltage

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LITERATURE REVIEW(D. Meneses, F. Blaabjerg, O. Garcia, and J. A. Cobos, “Review and comparison of stepup transformerless topologies for photovoltaicAC-Module application,” IEEE Trans. Power Electron., vol. 28, no. 6, pp. 2649–2663, Jun. 2013.)

This paper presents a comprehensive review of step-up single-phase non-isolated inverters suitable for ac-module applications. In order to compare the most feasible solutions of the reviewed topologies, a benchmark is set.

(C. W. Li and X. He, “Review of non-isolated high step-up DC/DC converters in photovoltaic grid-connected applications,” IEEE Trans. Ind. Electron., vol. 58, no. 4, pp. 1239–1250, Apr. 2011.)

This paper is concerned with how to achieve high-step-up, low-cost, and high-efficiency dc/dc conversion which is the major consideration due to the low PV output voltage with the parallel-connected structure. The limitations of the conventional boost converters in these applications are analyzed.

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LITERATURE REVIEW(D. Zhou, A. Pietkiewicz, and S. Cuk, “A Three-Switch high-voltage converter,” IEEE Trans. Power Electron., vol. 14, no. 1, pp. 177–183, Jan.)

A novel single active switch two-diodes high-voltage converter is presented. This converter can operate into a capacitor-diode voltage multiplier, which offers simpler structure and control, higher efficiency, reduced electromagnetic interference (EMI), and size and weight savings compared with traditional switched-mode regulated voltage multipliers.

(E. H. Ismail, M. A. Al-Saffar, A. J. Sabzali, and A. A. Fardoun, “A family of single-switchPWM converters with high step-up conversion ratio,” IEEE Trans. Circuits Syst. I, Reg Papers, vol. 55, no. 4, pp. 1159–1171,)

A new family of a single-switch three-diode dc-dc pulse width-modulated (PWM) converters operating at constant frequency and constant duty cycle is presented in this paper. The proposed converters are different from the conventional dc-dc step-up converters, and they posses higher voltage gain with small output voltage ripples.

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BLOCK DIAGRAM

SOLAR PANEL ARAY Vdc Vac Vgrid

MPPT Vpv SEPIC Vload CONVERTER

AC GRID

DG INTERFACED GRID CONNECTED SYSTEM WITH DISTRIBUTED GENRATOR (SOLAR , WIND , FUEL CELL…)

DC/DC DC/AC FILTER

LOAD

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OPEN LOOP CONFIGURATION

Vdc Vload

SOLARPANEL

SEPIC CONVERTER

DC/DCLOAD

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CLOSED LOOP CONFIGURATION

PWM PULSE FOR MOSFET SWITCH

CONTROL SIGNAL ERROR Vact

Vset

PANEL CONVERTER LOAD

PWM GENERATION

PI CONTROLLER VOLTAGESENSOR

+

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STIMULATION CIRCUIT

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HYBRID PSOGSA ALGORITHM

A new hybrid population-based algorithm (PSOGSA) is

proposed with the combination of Particle Swarm

Optimization (PSO) and Gravitational Search Algorithm

(GSA).

The main idea is to integrate the ability of exploitation in

PSO with the ability of exploration in GSA to synthesize

both algorithms’ strength.

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HYBRID PSOGSA FLOWCHART

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HYBRID PSOGSA ALGORITHM In PSOGSA, at first, all agents are randomly initialized.

Each agent is considered as a candidate solution. After initialization, Gravitational force, gravitational constant, and resultant forces among agents are calculated. After that, the accelerations of particles are defined as,

In each iteration, the best solution so far should be updated. After calculating the accelerations and with updating the best solution so far, the velocities of all agents can be calculated. Finally, the positions of agents are defined as,

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HYBRID PSOGSA ALGORITHM The process of updating velocities and positions will be stopped by meeting an end criterion. The steps of PSOGSA are represented in figure above. The agents near good solutions try to attract the other agents

which are exploring the search space. When all agents are near a good solution, they move very slowly.

In this case, the gBest help them to exploit the global best. PSOGSA use a memory (gBest) to save the best solution has

found so far, so it is accessible anytime. Each agent can observe the best solution so far and tend toward

it. With adjusting weighting factors , the abilities of global search and local search can be balanced.

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GATE PULSE GENERATION

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INPUT OUTPUT WAVEFORM

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HARDWARE CIRCUIT

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SPECIFICATIONSS.NO PARAMETERS SPECIFICATIONS

1. DIODE IN7004

2. POWER MOSFET IRFP460

3. OPTO ISOLATORS PC817

4. MICROCONTROLLER PIC16F877A

5. VOLTAGE REGULATOR IC7812

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HARDWARE KIT WITH OUTPUT

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OVERALL HARDWARE KIT COUPLING

INDUCTOR CONVERTER CIRCUIT SENSING

CIRCUIT MOTHER

BOARD TRIGGERING CIRCUIT

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CONVERTER CIRCUIT

DIODE( IN4007 )

POWER MOSFET (IRFP460) WITH HEAT SINK

FUSE

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MOTHER BOARD

LCD DISPLAY OSCILLATOR RESET KEY (PIC16F877A ) MICROCONTROLLER REGULATOR START AND

STOP KEY

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SENSING CIRCUIT OUTPUT VOLTAGE

SENSOR

INPUT CURRENT SENSOR

INPUT VOLTAGE SENSOR

OPAMP

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TRIGGERING CIRCUIT DIODE ( IN4007) RECTIFIER CIRCUIT

OPTO ISOLATOR (PC817)

REGULATORS

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RESULTPARAMETERS SEPIC

CONVERTER WITHOUT MAGNETIC COUPLING

SEPIC CONVERTER WITH MAGNETIC COUPLING

INPUT VOLTAGE(Vi) 15 V 15 V

OUTPUT VOLTAGE(Vo) 150 V 300VOUTPUT POWER (Po) 100 W 100 WSWITCHING FREQUENCY

24 KHZ 24 KHZ

DUTY CYCLE (D) 0.82 0.82

SWITCH VOLTAGE(Vs) 83 83STATIC GAIN (q) 10 20

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CONCLUSION A new topologies of nonisolated high static gain converters are

presented. The structure with magnetic coupling can operate with static gain

higher than 20 maintaining low the switch voltage. The efficiency of the proposed converter with magnetic coupling is

equal to 92.2% operating with input voltage equal to 15V, output voltage equal 300V, and output power equal 100W.

The commutation losses of the proposed converter with magnetic coupling are reduced due to the presence of the transformer leakage inductance and the secondary voltage multiplier that operates as a non dissipative clamping circuit to the output diode voltage

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