Automation of DC Motor Control using PWM Technique for thin film deposition

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1 Journal homepage: wwwmjretin ISSN: Automation of DC Motor Control using PWM Technique for thin film deposition 1 Akshaykumar A Nandi, 2 RBShettar, 3 Vaishali BM 4 Vinay Patil 1 Student, E & C Engg, BVB College of Engg&Tech, Hubli, Karnataka 2 Professor, E & C Engg, BVB College of Engg&Tech, Hubli, Karnataka 3 Principal, Sarvajanik College of Engg & Tech, Surat, Gujarat 4 CEO, NGX Technologies, Bangalore akshaynandinandi@gmailcom, raj@bvbedu, vaishalim@scetacin, vinay@ngxtechnologiescom, Abstract : We have developed a microcontroller based system to control speed and timing of a DC motor Pulse Width Modulation (PWM), a popular technique is used to control the speed of DC motor and the timing (duration) is controlled using in-built delay functions The system involves the interfaces, Keyboard, LCD and DC motor connected through I/O port and an Electronic Speed Controller(ESC) to drive the BLDC motor by providing the appropriate amount of current required The speed and timing (duration) of motor rotation are entered through the keyboard which can be visualized on the LCD The system is implemented and tested We have tested for (200 rpm, 10 sec), (10 rpm, 20 sec) and other ranges in this vicinity and found to be working satisfactorily We have used ATMEGA328P Microcontroller board for the implementation of the proposed system This system is the basic requirement of a Spin-Coating machine used in VLSI Fabrication laboratory Keywords: PWM, Automation of BLDC, Spin coating 1 INTRODUCTION TO SPIN COATING Spin coating is a process of uniformly coating a chemical (nano composite substance mainly) substance on the surface of a photo resist or an organic material A machine which performs this action is called a spin coater This process is widely used in the semiconductor industry, where it can be used to create thin films with thicknesses below 10 nm It is used intensively in photolithography, to deposit layers of photo resist about 1 micrometer thick Photo resist is typically spun at 1000 to 4000 revolutions per minute for 30 to 60 seconds Owing to the low values of thickness 80 P a g e

2 which can be achieved using spin coating methods, this method is often also employed in the fabrication of transparent titanium dioxide thin films on quartz or glass substrates, such thin film coatings may exhibit self-cleaning and self-sterilizing properties For example, PMMA is used for coating LCD display screens So the aim is to develop a spin coating machine which can produce thin films of photo resists of the order of micrometer It should be programmable by the user for controlling the speed and duration using a 4x4 keypad The output should be observed on an LCD display screen It should have an emergency key to stop the working in case of any unusual behavior of the machine 11 BLOCK DIAGRAM Fig1 shows the block diagram of the system that we are implementing Fig1 Block diagram of a spin coater 12 PULSE WIDTH MODULATION (PWM) TECHNIQUE (PWM) is a method for binary signals generation, which has 2 signal periods (high and low) The width (W) of each pulse varies between 0 and the period (T) The main principle is control of power by varying the duty cycle Internally, the motor speed is controlled by the average voltage given to the motor Here the conduction time to the 81 P a g e

3 load is controlled Let for a time t1, the input voltage appears across the load ie ON state and for t2 time the voltage across the load is zero Fig2 shows the graphical representation of PWM technique Fig2 graph of PWM signal variation Duty cycle = T on / (T on +T off ) (1) Where, T on = on time, T off = off time, and T on +T off = time period Equation (1) shows the calculation of duty cycle which computes the PWM signal graph 2 METHODOLOGY OF IMPLEMENTATION For implementing this application we need a controller board, BLDC motor, ESC, 4x4 keypad, 4x20 LCD display screen, vacuum chuck mechanism, power supply unit and a mechanical casing 21 Controller board We developed our own Arduino controller board using IC ATMEGA328P It consists of a 28 pin IC base, a crystal oscillator, 33 V and 5 V regulator, reset button and two power supply pins Fig3 shows the controller with arduino ATMEGA328P chip 82 P a g e

4 22 4x4 keypad Fig3 Arduino controller board for the application We require 8 pins for interfacing 4x4 keypad with the controller But using all 8 pins will leave less number of pins for other peripherals So we use ADC technique to connect the keypad with the arduino We first find out the ADC value of each key pressed in the keypad and then we will write the code accordingly The circuit for such a keypad arrangement is given below in Fig4 Fig4 4x4 keypad interface with arduino We fabricated our own keypad PCB as shown in below Fig 5 83 P a g e

5 Fig5 Fabricated PCB keypad for interfacing with arduino 23 LCD display screen The display screen that we used is 20x4 LCD screen Fig 6 shows the LCD display screen 24 HDD BLDC motor Fig6 LCD 20X4 The motor we used is brushless dc (BLDC) motor dismantled from a damaged hard disk drive (HDD) of a computer system It has a maximum 84 P a g e

6 RPM of 7200 and takes 15 A of current for it s operation Fig 7 shows a HDD BLDC motor Fig7 HDD BLDC RPM & 15 A rating 25 Electronic Speed Controller (ESC) The ESC is a driver circuit that can take on heavy loads, and it gives a current rating of upto 30 A Actually the motor needs only 15 A for its operation So in real time operation the motor takes only 15 A from the ESC Fig 8 visualizes an ESC Fig8 Electronic Speed A rating 85 P a g e

7 26 Hall effect sensor The Hall Effect sensor is a device that is used to calculate the RPM of the motor This is achieved by placing a magnet in the vicinity of the motor By coding we can set a particular mark on the motor So whenever this mark comes near the magnet, a value is incremented So the number of counts recorded per minute will give us the rotations per minute, hence RPM is calculated Fig 9 shows the Hall effect sensor Fig 9 Hall effect sensor 27 Vacuum Chuck mechanism The vacuum chuck mechanism plays a very important role in holding the substrate so that it does not fly away The necessary centrifugal force required for the spinning of the substrate is provided by the pressure created by the vacuum chuck mechanism In Fig 10, vacuum chuck mechanism is illustrated Fig 10 vacuum chuck mechanism 86 P a g e

8 28 Overall product The product casing is done using a mixer compartment taken from a scrap yard and cleaned and finally spray painted so as to look aesthetically pleasing It is visualized as shown below in Fig11 Fig 11 Overall implementation of the product 3 BUDGET ANALYSIS Table 1 shows the detailed budget that was required for our project 87 P a g e

9 1 HDD BLDC motor x4 keypad Arduino IC LCD ESC Hall effect sensor Connecting wires As required Vacuum chuck mechanism Transformer capacitors As required resistors As required diodes regulator IC casing for the product V regulator crystal oscillator 1 10 Total 2680 Table 1 Budget analysis for the proposed system 4 CONCLUSION & FUTURE SCOPE 41 Conclusion A system working according to our requirements is implemented using the above explained tools and the components we used are tested for their working individually first and then they are integrated with the DC motor to implement the whole system The machine can be used for the IC fabrication in VLSI field and also by the various institutes in their respective colleges or research centers 42 Future scope 1 The project can be extended to the commercial sector by marketing it in a proper way by appropriately making cost effective as per market values of components 2 Study of Nano-scale properties of deposited material as we could not carry out this due to lack of resources / testing equipment 3 Other similar product prototypes can be built by following the same methodology we have used 88 P a g e

10 5 ACKNOWLEGEMENT The completion of any inter-disciplinary project depends upon cooperation, co-ordination and combined efforts of several sources of knowledge We would like to express our thanks to NGX technologies, Bangalore, for their valuable inputs from beginning to end of the work We sincerely thank Dr Anil Nandi for regularly reviewing our work during the course of project REFERENCES [1] Muhammad Ali Mazidi, Janice Gillispie Mazidi, The 8051 Microcontroller and Embedded Systems Using Assembly and C, 2nd Edition [2] Simon Monk, Programming Arduino: getting started with sketches [3] wwwyoutubecom/user/programmingknowledge [4] [5] [6] 89 P a g e