Int. Journal of Electrical & Electronics Engg.
Vol. 2, Spl. Issue 1 (2015)
e-ISSN: 1694-2310 | p-ISSN: 1694-2426
Automated Air Cooled Three Level Inverter system using Arduino Alok Deep1, Jyoti Singh2, Shimi S.L3 1,2,3
Department of Electrical Engineering, NITTTR, Chandigarh, India
Abstract—The output voltage of a three level inverter is stepped voltage in which the output voltage have three possible values. Such systems can be used to interface renewable energy sources with the grid. Temperature has significant effect on performance of power MOSFETs. Typically, the MOSFETs used as power switches in such applications are a significant source of heat, and the heat energy dissipated by these components must be carefully controlled if operating temperatures are to be maintained. So for the system to work efficiently cooling of MOSFETs is required. This paper proposed an automated air cooled 3 level 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. When temperature rises above certain level fan turns on to cool the MOSFETs. Keywords — Arduino, MATLAB, MOSFETs, Optocouplers, LM 35, Cooling Fan.
INTRODUCTION Power Electronics is interdisciplinary and is at the confluence of three fundamental technical areas - power, electronics and control, and is used in a wide variety of industries from computers, chemical plants to rolling mills. The importance of power electronics has grown over the years due to several factors. MATLAB have been used for simulating the power electronic circuits like rectifiers, inverters, choppers and ac voltage controllers. They have the detailed device models and have been able to represent the controller portion of the converter system by its functional features in as a simplified manner as possible. In this paper the simulation and hardware implementation of a three level inverter circuit and cooling of the system has been taken into consideration. A 3 Level Inverter is a high-efficiency power electronic inverter particular, for use with three-phase drives, as a grid-tie inverter for photovoltaic installations or wind turbines and in power supplies [1]. Some industrial applications of inverters are for adjustable- speed ac drives, induction heating, stand by air-craft power supplies, UPS (uninterruptible power supplies) for computers, HVDC transmission lines etc. This converter topology used MOSFET power semiconducting devices it is act as a switches. While designing inverter with power electronic devices cooling of power electronic components is always required because of their high power ratings. In MOSFET when the temperature increases above 25oC the normalized onresistance increases and load current decreases, and hence efficiency of system goes down [2].
To increase the efficiency we design a system to maintain its temperature at 25oC by fan cooling which is controlled by Arduino Microcontroller Board [3]. In section 2 a simplified block diagram of the proposed system and overview of Arduino Uno are discussed. The section 3 describes the proposed work and circuit diagram of system. In Section 4 the flow of process is shown. In section 5, 6 and 7 the MATLAB simulation model, hardware implementation and output waveforms of system are discussed respectively. The Section 8 discusses all the conclusion and future development of project. BLOCK DIAGRAM DESCRIPTION The goal of this project is to improve the efficiency of 3 level inverter by maintaning the operating temperature of MOSFETs at 25oC. The system consists of a power supply, a cooling fan, MOSFET bridge, Optocouplers for isolation of power circuit from control circuit and Arduino [4-5]. The simplified block diagram of the system is shown in Fig. 1.
Fig. 1 Block diagram of System Over view of Arduino Arduino is an open-source electronics prototyping platform, mostly based on small, easy-to-use hardware and software [6-7]. It can affect devices, like lights, motors and other actuators by receiving input from sensor. All the action performed by Arduino is programmed to the microcontroller on the board via Arduino programming language and the Arduino development environment. Arduino projects can be stand-alone or communicate with other software applications running on a computer and other types of hardware.
Fig. 2 Arduino Uno Microcontroller Development Board NITTTR, Chandigarh
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Int. Journal of Electrical & Electronics Engg.
Vol. 2, Spl. Issue 1 (2015)
The Adruino Uno board as shown in Fig. 2. The Table.1 shows the specifications of Arduino Uno microcontroller board. Table.1 Arduino Uno specifications Microcontroller Operating Voltage Supply Voltage (recommended) Maximum supply Voltage (not recommended) Digital I/O Pins Analog Input Pins DC Current per I/O Pin DC Current for 3.3V Pin Flash Memory SRAM EEPROM Clock Speed
ATmega328 5V 7-12V 20V
e-ISSN: 1694-2310 | p-ISSN: 1694-2426
The objective is to maintain the temperature of MOSFETs at 25oC. To do this we use fan cooling with the help of Arduino. Whenever temperature increases above 25oC the cooling fan is switched on to cool the system [12]. The inverting program have developed in C code in Arduino which compares the temperature of MOSFETs with 25oC. If it increases above the set value the fan is turned on. FLOWCHART OF PROCESS
14(of which 6 provide PWM output) 6 40mA 50mA 32KB of which 0.5KB used by boot loader 2KB 1KB 16MHz
PROPOSED CIRCUIT & ITS OPERATION The circuit diagram for proposed automated air cooled inverter circuit is shown in Fig. 3.The dc power supply taken from the rectifier or from solar or by any other mean [8]. The dc power output is fed to the inverter bridge which consists of four MOSFETs. The temperature of MOSFETs are continuously sensed by temperature sensor IC LM35 [9-11]. ArduinoUno takes the temperature from LM35 and shows reading on display. The gate pulse for MOSFETs is given by Arduino. Optocoupler is used to isolate two voltage level. It is an electronic components that interconnects two separate electrical circuits by means of a light sensitive optical interface. The control circuit consists of microcontroller which operates on TTL logic and the power circuit consists of power MOSFETs of very high voltage (400V) and current rating(10A).
Fig. 4 Flow Chart of Process From the flow chart it can be seen that the temperature is continuously monitored by Arduino via LM35. Temperature sensor checks the temperature of MOSFETs. If the temperature rises above the set value cooling fan gets turn on. And if there is no change or the temperature is below the desired value the fan remain off. MATLAB BASED SIMULATION MODEL The model is implemented using MATLAB/SIMULINK software with the SimPowerSystem Block Set based on computer simulation. Computer simulation plays an important role in the design, analysis, and evaluation of power electronic converter and their controller. The Fig. 5 shows MOSFET based full bridge inverter circuit diagram in MATLAB. In this circuit Vs is 12V, load R, resistance is 200kohm. The output waveform shown in Fig. 6.
Fig. 3 Circuit diagram for H-Bridge 3 Level Inverter LM35 gives the present temperature in the form of voltage to the Arduino board. As the MOSFETs switched on continuously it gets heated and affects the output load current as shown in Fig.4 and hence system performance decreases. It can be seen that the load current is maximum at 25oC. 181
Fig. 5 MOSFET Based H-Bridge Inverter in MATLAB
NITTTR, Chandigarh
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Int. Journal of Electrical & Electronics Engg.
Vol. 2, Spl. Issue 1 (2015)
e-ISSN: 1694-2310 | p-ISSN: 1694-2426
RESULT & DISCUSSION
Fig. 6 Output Voltage Waveform Triggering Gate Pulses and Inverter Output HARDWARE IMPLEMENTATION Here single phase dc supply is given to the three level inverter. It will convert the dc voltage to stepped dc voltage. As shown in the Fig. 7 three level inverter consists of four power MOSFETs (IRF740) for H-Bridge. For triggering of MOSFETs Arduino Uno is used. As the control circuit consists of microcontroller, Optocoupler (MCT2E) is used to isolate the control circuit and power circuit. Power MOSFETs get heated during the operation. So a cooling fan system was to maintain the temperature of MOSFETs at 25oC. Inverter output waveforms on CRO is shown in Fig. 8.
Fig. 9 Variation of output current with temperature The simulation of proposed circuit is carried out by gate triggering with MATLAB software and practically implemented. It is observed in Fig. 9 that output current reduces as the temperature of MOSFET rises, load current decreases 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 observed from the Fig. 10. It can be analyzed as the temperature of MOSFETs goes high than 25o C the fan turn on and it try to maintain the temperature of MOSFETs at 25o C. As the temperature is maintained at desired value the load current is optimum.
Fig. 7 Three Level Inverter
CONCLUSION & FUTURE SCOPE It is conclude from Fig. 9 that maximum load current from MOSFET and optimum use of the system is at 25o C and from Fig. 10 the stabilization in temperature are obtained. So the Automated Air Cooling System helps the MOSFETs to maintain the temperature at 25o C continuously. Hence efficiency of the system is improved. Fig. 8 Output Waveform of System on CRO
Improvements can be attained in the stabilization of temperature using PID controller because it is more efficient then on-off controller. ACKNOWLEDGMENT We would like to thank Dr. Lini Mathew, Associate Professor, Electrical Engineering Department, NITTTR Chandigarh for guiding us to proceed with this project smoothly.
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Int. Journal of Electrical & Electronics Engg.
Vol. 2, Spl. Issue 1 (2015)
e-ISSN: 1694-2310 | p-ISSN: 1694-2426
REFERENCES 1) Abhijit Choudhury, Pragasen Pillay and Sheldon S. Williamson, “Comparative Analysis Between Two-Level and Three-Level DC/AC Electric Vehicle Traction Inverters Using a Novel DC-Link Voltage Balancing Algorithm”, IEEE Journal of Emerging and selected Topics in Power Electronics, vol. 2, pp-529-540, Sept 2014. 2) Desikan Bharathan, Kenneth Kelly, “An Assessment of Air Cooling for use with Automotive Power Electronics”, 11th Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic 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”, International Conference on Recent Trends in Information, Telecommunication and Computing, Kerala, pp 293 – 297, Mar 2010. 4) Olivier Gilard, Pamela Del Vecchio, Richard Moglia, Laurent Béchou, and Gianandrea Quadri, “Hardening Principle and Characterization of an Optocoupler Including a Vertical Cavity Surface Emmiting Laser”, IEEE/ASME Transactions on Nucler Science, vol .59, pp 1717-1721, Aug 2012. 5) Gerald W. Recktenwald, David E. Hall, “AC 2011-2062: Using Arduino as a Platform for Programming, Design and Measurement in a Fresh Engineering Course”, 118th ASEE Annual Conference & Exposition, Canada, June 2011. 6) Pavlo Denysyuk, Taras Teslyuk, “Main algorithm of mobile robot system based on the Microcontroller Arduino”, XVIII International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustiv Wave Theory( DIPED), Lviv, Sept 2013. 7) Radhika Grover, Shoba Krishnan, Terry Shoup, Maryam hanbaghi, “A Competition-Based Approach for Undergraduate Mechatronics Education Using the Arduino Platform”, 4th Interdisciplinary Engineering Design Education Conference (IEDEC), Santa Clara, CA, pp 78-83, Mar 2014. 8) Yongsoon Park, Seung-Ki Sul, Chun-Ho Lim,Woo-Chull Kim, and Seong-Hun Lee, “Asymmetric Control of DC-Link Voltages for Separate MPPTs in Three-Level Inverters”, IEEE Transaction on Power Electronics, vol .28, pp-2760 – 2769, June 2013. 9) Yongchang Zhang, Zhengming Zhao, Jianguo Zhu, “A Hybrid PWM Applied to High-Power Three-Level Inverter-Fed Induction-Motor Drives”, ”, IEEE Transaction on Industrial Electronics, vol .58, pp3409-3420, Aug 2011. 10) June-Seok Lee, Kyo-Beum Lee, “New Modulation Techniques for a Leakage Current Reduction and a Neutral-Point Voltage Balance in Transformerless 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 Temperature Monitoring In Oil Palm Bio-Laboratory”, Fifth International Conference on MEMS, NANO, and Smart Systems (ICMENS), Dubai, pp 234-238, Dec 2009. 12) Kergh Benjamin Wrzecionko, Andreas Looser, Johann W. Kolar, and Michael Casey, “High-Temperature (250 ◦C/ 500 ◦F) 19 000 min-1 BLDC Fan for Forced Air-Cooling of Advanced Automotive Power Electronics”, IEEE/ASME Transactions on Mechatronics, vol .20, pp 37-49, Mar 2014.
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