automated air cooled three level inverter system using arduino

Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426

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Automated Air Cooled Three Level Invertersystem using Arduino

Alok Deep1, Jyoti Singh2, Shimi S.L3

1,2,3Department of Electrical Engineering, NITTTR, Chandigarh, India

Abstract—The output voltage of a three level inverter isstepped voltage in which the output voltage have threepossible values. Such systems can be used to interfacerenewable energy sources with the grid. Temperature hassignificant effect on performance of power MOSFETs.Typically, the MOSFETs used as power switches in suchapplications are a significant source of heat, and the heatenergy dissipated by these components must be carefullycontrolled if operating temperatures are to be maintained. Sofor the system to work efficiently cooling of MOSFETs isrequired. This paper proposed an automated air cooled 3level H-bridge inverter. The system consists of MOSFETs,LM 35 temperature sensor, Optocouplers for isolation.Arduino is used to control the on-off operation of fan. Whentemperature rises above certain level fan turns on to cool theMOSFETs.

Keywords — Arduino, MATLAB, MOSFETs, Optocouplers,LM 35, Cooling Fan.

INTRODUCTION

Power Electronics is interdisciplinary and is at theconfluence of three fundamental technical areas - power,electronics and control, and is used in a wide variety ofindustries from computers, chemical plants to rolling mills.The importance of power electronics has grown over theyears due to several factors. MATLAB have been used forsimulating the power electronic circuits like rectifiers,inverters, choppers and ac voltage controllers. They havethe detailed device models and have been able to representthe controller portion of the converter system by itsfunctional features in as a simplified manner as possible. Inthis paper the simulation and hardware implementation ofa three level inverter circuit and cooling of the system hasbeen taken into consideration.

A 3 Level Inverter is a high-efficiency powerelectronic inverter particular, for use with three-phasedrives, as a grid-tie inverter for photovoltaic installationsor wind turbines and in power supplies [1]. Some industrialapplications of inverters are for adjustable- speed ac drives,induction heating, stand by air-craft power supplies, UPS(uninterruptible power supplies) for computers, HVDCtransmission lines etc.

This converter topology used MOSFET powersemiconducting devices it is act as a switches. Whiledesigning inverter with power electronic devices cooling ofpower electronic components is always required because oftheir high power ratings. In MOSFET when thetemperature increases above 25oC the normalized on-resistance increases and load current decreases, and henceefficiency of system goes down [2].

To increase the efficiency we design a system tomaintain its temperature at 25oC by fan cooling which iscontrolled by Arduino Microcontroller Board [3].

In section 2 a simplified block diagram of the proposedsystem and overview of Arduino Uno are discussed. Thesection 3 describes the proposed work and circuit diagramof system. In Section 4 the flow of process is shown. Insection 5, 6 and 7 the MATLAB simulation model,hardware implementation and output waveforms of systemare discussed respectively. The Section 8 discusses all theconclusion and future development of project.

BLOCK DIAGRAM DESCRIPTION

The goal of this project is to improve the efficiency of 3level inverter by maintaning the operating temperature ofMOSFETs at 25oC. The system consists of a power supply,a cooling fan, MOSFET bridge, Optocouplers for isolationof power circuit from control circuit and Arduino [4-5].The simplified block diagram of the system is shown inFig. 1.

Fig. 1 Block diagram of System

Over view of Arduino

Arduino is an open-source electronics prototypingplatform, mostly based on small, easy-to-use hardware andsoftware [6-7]. It can affect devices, like lights, motorsand other actuators by receiving input from sensor. All theaction performed by Arduino is programmed to themicrocontroller on the board via Arduino programminglanguage and the Arduino development environment.Arduino projects can be stand-alone or communicate withother software applications running on a computer andother types of hardware.

Fig. 2 Arduino Uno Microcontroller Development Board


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The Adruino Uno board as shown in Fig. 2. TheTable.1 shows the specifications of Arduino Unomicrocontroller board.

Table.1 Arduino Uno specificationsMicrocontroller ATmega328Operating Voltage 5VSupply Voltage(recommended)

7-12V

Maximum supply Voltage(not recommended)

20V

Digital I/O Pins 14(of which 6 provide PWMoutput)

Analog Input Pins 6DC Current per I/O Pin 40mADC Current for 3.3V Pin 50mAFlash Memory 32KB of which 0.5KB used

by boot loaderSRAM 2KBEEPROM 1KB

Clock Speed 16MHz

PROPOSED CIRCUIT & ITS OPERATION

The circuit diagram for proposed automated air cooledinverter circuit is shown in Fig. 3.The dc power supplytaken from the rectifier or from solar or by any other mean[8]. The dc power output is fed to the inverter bridge whichconsists of four MOSFETs. The temperature of MOSFETsare continuously sensed by temperature sensor IC LM35[9-11]. ArduinoUno takes the temperature from LM35 andshows reading on display.

The gate pulse for MOSFETs is given by Arduino.Optocoupler is used to isolate two voltage level. It is anelectronic components that interconnects two separateelectrical circuits by means of a light sensitive opticalinterface. The control circuit consists of microcontrollerwhich operates on TTL logic and the power circuitconsists of power MOSFETs of very high voltage (400V)and current rating(10A).

Fig. 3 Circuit diagram for H-Bridge 3 Level Inverter

LM35 gives the present temperature in the form ofvoltage to the Arduino board. As the MOSFETs switchedon continuously it gets heated and affects the output loadcurrent as shown in Fig.4 and hence system performancedecreases. It can be seen that the load current is maximumat 25oC.

The objective is to maintain the temperature ofMOSFETs at 25oC. To do this we use fan cooling with thehelp of Arduino. Whenever temperature increases above25oC the cooling fan is switched on to cool the system [12].The inverting program have developed in C code inArduino which compares the temperature of MOSFETswith 25oC. If it increases above the set value the fan isturned on.

FLOWCHART OF PROCESS

Fig. 4 Flow Chart of Process

From the flow chart it can be seen that the temperatureis continuously monitored by Arduino via LM35.Temperature sensor checks the temperature of MOSFETs.If the temperature rises above the set value cooling fan getsturn on. And if there is no change or the temperature isbelow the desired value the fan remain off.

MATLAB BASED SIMULATION MODEL

The model is implemented using MATLAB/SIMULINKsoftware with the SimPowerSystem Block Set based oncomputer simulation. Computer simulation plays animportant role in the design, analysis, and evaluation ofpower electronic converter and their controller. The Fig. 5shows MOSFET based full bridge inverter circuit diagram inMATLAB. In this circuit Vs is 12V, load R, resistance is200kohm. The output waveform shown in Fig. 6.

Fig. 5 MOSFET Based H-Bridge Inverter in MATLAB


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Fig. 6 Output Voltage Waveform Triggering Gate Pulsesand Inverter Output

HARDWARE IMPLEMENTATION

Here single phase dc supply is given to the three levelinverter. It will convert the dc voltage to stepped dcvoltage. As shown in the Fig. 7 three level inverter consistsof four power MOSFETs (IRF740) for H-Bridge. Fortriggering of MOSFETs Arduino Uno is used. As thecontrol circuit consists of microcontroller, Optocoupler(MCT2E) is used to isolate the control circuit and powercircuit. Power MOSFETs get heated during the operation.So a cooling fan system was to maintain the temperature ofMOSFETs at 25oC. Inverter output waveforms on CRO isshown in Fig. 8.

Fig. 7 Three Level Inverter

Fig. 8 Output Waveform of System on CRO

RESULT & DISCUSSION

Fig. 9 Variation of output current with temperature

The simulation of proposed circuit is carried out by gatetriggering with MATLAB software and practicallyimplemented. It is observed in Fig. 9 that output currentreduces as the temperature of MOSFET rises, load currentdecreases as the temperature of MOSFETs increases.Maximum current appears at 25o C.

Fig. 10 Variation of Temperature with respect to time

The variations of temperature with time are observedfrom the Fig. 10. It can be analyzed as the temperature ofMOSFETs goes high than 25o C the fan turn on and it try tomaintain the temperature of MOSFETs at 25o C. As thetemperature is maintained at desired value the load currentis optimum.

CONCLUSION & FUTURE SCOPE

It is conclude from Fig. 9 that maximum load currentfrom MOSFET and optimum use of the system is at 25o Cand from Fig. 10 the stabilization in temperature areobtained. So the Automated Air Cooling System helps theMOSFETs to maintain the temperature at 25o Ccontinuously. Hence efficiency of the system is improved.

Improvements can be attained in the stabilization oftemperature using PID controller because it is moreefficient then on-off controller.

ACKNOWLEDGMENT

We would like to thank Dr. Lini Mathew, AssociateProfessor, Electrical Engineering Department, NITTTRChandigarh for guiding us to proceed with this projectsmoothly.


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REFERENCES1) Abhijit Choudhury, Pragasen Pillay and Sheldon S. Williamson,

“Comparative Analysis Between Two-Level and Three-Level DC/ACElectric Vehicle Traction Inverters Using a Novel DC-Link VoltageBalancing Algorithm”, IEEE Journal of Emerging and selectedTopics in Power Electronics, vol. 2, pp-529-540, Sept 2014.

2) Desikan Bharathan, Kenneth Kelly, “An Assessment of Air Coolingfor use with Automotive Power Electronics”, 11th IntersocietyConference on Thermal and Thermomechanical Phenomena inElectronic Systems, Orlando, pp 37-43, May 2008.

3) Balraj A, Patvardhan A, Renuka Devi V, Aiswarya R, Parsen V,“Embedded Temperature Monitoring and Control Unit”, InternationalConference on Recent Trends in Information, Telecommunicationand Computing, Kerala, pp 293 – 297, Mar 2010.

4) Olivier Gilard, Pamela Del Vecchio, Richard Moglia, LaurentBéchou, and Gianandrea Quadri, “Hardening Principle andCharacterization of an Optocoupler Including a Vertical CavitySurface Emmiting Laser”, IEEE/ASME Transactions on NuclerScience, vol .59, pp 1717-1721, Aug 2012.

5) Gerald W. Recktenwald, David E. Hall, “AC 2011-2062: UsingArduino as a Platform for Programming, Design and Measurement ina Fresh Engineering Course”, 118th ASEE Annual Conference &Exposition, Canada, June 2011.

6) Pavlo Denysyuk, Taras Teslyuk, “Main algorithm of mobile robotsystem based on the Microcontroller Arduino”, XVIII InternationalSeminar/Workshop on Direct and Inverse Problems ofElectromagnetic and Acoustiv Wave Theory( DIPED), Lviv, Sept2013.

7) Radhika Grover, Shoba Krishnan, Terry Shoup, Maryam hanbaghi,“A Competition-Based Approach for Undergraduate MechatronicsEducation Using the Arduino Platform”, 4th InterdisciplinaryEngineering Design Education Conference (IEDEC), Santa Clara,CA, pp 78-83, Mar 2014.

8) Yongsoon Park, Seung-Ki Sul, Chun-Ho Lim,Woo-Chull Kim, andSeong-Hun Lee, “Asymmetric Control of DC-Link Voltages forSeparate MPPTs in Three-Level Inverters”, IEEE Transaction onPower Electronics, vol .28, pp-2760 – 2769, June 2013.

9) Yongchang Zhang, Zhengming Zhao, Jianguo Zhu, “A Hybrid PWMApplied to High-Power Three-Level Inverter-Fed Induction-MotorDrives”, ”, IEEE Transaction on Industrial Electronics, vol .58, pp-3409-3420, Aug 2011.

10) June-Seok Lee, Kyo-Beum Lee, “New Modulation Techniques for aLeakage Current Reduction and a Neutral-Point Voltage Balance inTransformerless Photovoltaic Systems Using a Three-Level Inverter”,IEEE Transactions on Power Electronics, vol. 29, Apr 2014

11) Noor Hafizah Abdul Aziz, Kama Azura Othman, Suzi Seroja Sarnin,Yuhaini Idayu Mohd Ali, “Wireless System for TemperatureMonitoring In Oil Palm Bio-Laboratory”, Fifth InternationalConference on MEMS, NANO, and Smart Systems (ICMENS),Dubai, pp 234-238, Dec 2009.

12) Kergh Benjamin Wrzecionko, Andreas Looser, Johann W. Kolar, andMichael Casey, “High-Temperature (250 ◦C/ 500 ◦F) 19 000 min-1BLDC Fan for Forced Air-Cooling of Advanced Automotive PowerElectronics”, IEEE/ASME Transactions on Mechatronics, vol .20,pp 37-49, Mar 2014.