“Speed Control of a Switched Reluctance MotorUsing Microcontroller” Major Project report submitted in partial fulfillment of the requirements For the award of the degree of BACHELOR OF TECHNOLOGY IN ELECTRICAL AND ELECTRONICS ENGINEERING By DEEPTHI.S (08241A0207) JHANSI RANI.CH (08241A0213) MOUNICA.P (08241A0223) Department of Electrical and Electronics Engineering GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING & TECHNOLOGY, BACHUPALLY, HYDERABAD-72 2008 – 2012 GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING AND TECHNOLOGY Hyderabad, Andhra Pradesh. DEPARTME NT OF E CERTIFICATE This is to certify that the major-project report entitled SPEED CONTROL OF A SWITCHED RELUCTANCE MOTOR USING MICROCONTROLLER that is being submitted by MOUNICA.P, JHANSI RANI.CH, DEEPTHI.S in partial fulfillment for the award of the Degree of Bachelor of Technology in Electrical and Electronics Engineering to the Jawaharlal Nehru Technological University is a record of bonafide work carried out by them under my guidance and supervision. The results embodied in this project report have not been submitted to any other University or Institute for the award of any Graduation degree. Mr.P.M.Sarma Mr. C.K.sarma HOD, EEE Professor GRIET Dept. of EEE Hyderabad GRIET External Examiner ACKNOWLEDGEMENT This is to place on record my appreciation and deep gratitude to the persons Without whose support this project would never seen the light of day. I wish to express my propound sense of gratitude to Mr. P. S. Raju, Director, G.R.I.E.T for his guidance, encouragement, and for all facilities to complete this project. I also express my sincere thanks to Mr.P.M.Sarma, Head of the Department, G.R.I.E.T and for extending their help. I have immense pleasure in expressing my thanks and deep sense of gratitude to my guide Mr. C.K.Sarma, Professor, Department of Electrical and Electronics Engineering, G.R.I.E.T for his guidance throughout this project. Finally I express my sincere gratitude to Mr. S. N.Saxena, Professor, Department of Electrical and Electronics Engineering, G.R.I.E.T and Mr.R.Anil Kumar, Assistant Professor, Department of Electrical and Electronics Engineering, G.R.I.E.T, and all the members of faculty and my friends who contributed their valuable advice and helped to complete the project successfully. DEEPTHI.S (08241A0207) JHANSIRANI.CH (08241A0213) MOUNICA.P i (08241A0223) For a unidirectional torque.ABSTRACT Switched reluctance motor (like the stepper motor) carries windings only on the stator and operates on the reluctance principle .Its rotor position is sensed and used to switch on and switch off phase windings. fans. vacuum cleaner. but it does depend on change in inductance with respect to rotor position. It is now being made up to 0. aircrafts. servo drives.5 to 80 KW and it is used in applications like washing machine. Direction of the developed torque does not depend on the direction of current. ii . current must be present in the coil only when the rate of change of coil inductance with rotor position is positive. Study of switching methods to obtain currents of the desired waveforms in an inductance are the main aim of the project. Fuel pump operations etc Inductance of a phase winding in a switched reluctance motor varies with rotor position. 1. Hardware Description 5.1 Pulses for MOSFET Q1 6.4 2.3 2.6.1Specification of Switched Reluctance Motor 6. Schematic Connections in Proteus 6.1 1. Software Code 5. Converters For Switched Reluctance Motor Drives 3. Introduction 1.2 Pulses for MOSFET Q2 6. Switched Reluctance Motor Controllers 2.3 Power Converter Topology Energizing the Switched Reluctance Motor Torque Speed Characteristics of a Switched Reluctance Motor 4.2.4 Switching Circuit of Switched Reluctance Motor for Three Phases 6.1 3.1 Current waveform 6.1 Current waveforms 6.3.3 About Switched Reluctance Motor Advantages and Disadvantages of Switched Reluctance Motor Desired Waveform of Current In a Stator Coil 2.6 EAGLE designs 6.1 2.2 3.1.CONTENTS 1.5 Construction Principle of Operation The Relationship Between Inductance and Rotor Position Aligned Inductance and Unaligned Inductance To Obtain the Current Waveform 3.2 1.6.2 Power supply circuit for Switched Reluctance Motor 6.1 Schematic layout of power supply circuit 6.1 Power supply circuit to the microcontroller 5.1 Current waveform 6.1 Power Supply Section 5.5 Simulation In MATLAB Software 6.1.1 Switching for MOSFET 6.2 Switching Circuit of Switched Reluctance Motor for Single Phase 6.5.2 Board layout of power supply circuit iii .4.1.2Switched Reluctance Motor characteristics in MATLAB 6.3 Switching Circuit of Switched Reluctance Motor for Two Phases 6.2 2.5. 2 Simulation in MATLAB 7.1 Simulation in Proteus 6.3 Schematic layout of driver circuit 6. Conclusion and Scope for Future Work References Appendix A Appendix B Appendix C Appendix D Appendix E iv .4 7.6.1 First Difficulty 7.5 Power Supply Circuit Driver Circuit Microcontroller Circuit Interfacing Microcontroller with Driver Circuit Complete Circuit Testing 7.7 Difficulties Encountered During Simulation 6.6.2 Second Difficulty 8.1 current waveform 7.6.7.6 Difficulties Encountered on Hardware 7.5.7.3 7.6. Hardware Implementation 7.1 7.2 7. LIST OF FIGURES Figure 2.1 ------------------------------ 6/4 pole machines Figure 2.2 ------------------------------ Four distinct inductance regions emerge Figure 2.3 ------------------------------ Inductance profile Figure 2.4 ------------------------------ Aligned Position Figure 2.5 ------------------------------ Voltage PWM-Hard/Soft chopping Figure 2.6 ------------------------------ General Motor Control Design Figure 3.1------------------------------- Variation of reluctance of the flux path of a phase Figure 3.2 ------------------------------ Half-Bridge Inverter Figure 3.3 ------------------------------ Torque Speed Characteristics of a Switched Reluctance Motor Figure 5.1 ------------------------------ Power supply Circuit for microcontroller Figure 5.2 ------------------------------ Power Supply Circuit for Switched Reluctance Motor Figure 6.1 ------------------------------ Switching circuit of Switched Reluctance Motor for three phases Figure 6.2 ------------------------------ Current waveform across three phase windings Figure 6.3 ------------------------------ Circuit connections in MATLAB Figure 6.4 ------------------------------ Switched Reluctance Motor characteristics in MATLAB simulation v CHAPTER 1 INTRODUCTION 1.1 ABOUT SWITCHED RELUCTANCE MOTOR Electrical machines can be classified into two categories on the basis of how torque is developed in them: electromagnetically or through variation of reluctance. In the first category, motion is produced by the interaction of two magnetic fields, one generated by the stator and the other by the rotor. Two magnetic fields, mutually coupled, produce an electromagnetic torque tending to bring the fields into alignment. The same phenomenon causes opposite poles of bar magnets to attract and like poles to repel. The vast majority of motors in commercial use today operate on this principle. In the second category, motion is produced as a result of the variable reluctance in the air gap between the rotor and the stator. When a stator winding is energized, producing a single magnetic field, reluctance torque is produced by the tendency of the rotor to move to its minimum reluctance position. This phenomenon is analogous to the force that attracts iron or steel to permanent magnets. In those cases, reluctance is minimized when the magnet and metal come into physical contact. Switched reluctance motor falls into this class of machines. In Switched reluctance motor, switching of supply from one stator to the next causes minimum reluctance position of the rotor to change continuously thus producing rotation. By controlling the switching strategy, and the current flowing through the stator coils, we can control the torque and the speed of the motor. Because of their simple mechanical construction switched reluctance motors are of low cost. This has motivated a large amount of research on these motors in the last decade. The mechanical simplicity of the device, however, comes with some limitations. Like the brushless dc motor, switched reluctance motors cannot run directly from a dc bus or an ac bus, but must always be electronically commutated. Also, the saliency of the stator and rotor, necessary for the machine to produce reluctance torque, causes strong non-linear magnetic characteristics, complicating the analysis and control of the Switched Reluctance Motor. 1.2 Advantages and Disadvantages of Switched Reluctance Motor: Advantages: The switched reluctance motor possess a few unique features that makes it a vigorous competitor to existing AC and DC motors in various adjustable-speed drive and servo applications. 1. The torque–speed characteristics of the motor can be modified to the application requirement more easily during the design stage than in the case of induction and permanent magnetic machines. 2. The starting torque can be very high without the problem of excessive in-rush current due to its higher Self inductance. 3. There are independent stator phases, which do not prevent drive operation in the case of loss of one or more phases. 1 Disadvantages: The Switched Reluctance Motor also comes with a few disadvantages among which torque ripple and acoustic noise are the most critical. The higher torque ripple also causes the ripple current in the DC supply to be quite large, necessitating a large filter capacitor. 1.3 Desired waveform of current in a stator coil The ideal waveform of current in a stator phase will be shown to be a square waveform. The attempt is to get the actual waveform as close to the ideal as possible. 2 This is a distinct advantage in that only one power switch is required for control of current in a phase winding. there will not be any developed torque on the rotor. Figure 2.1 6/4 pole machines 2. Expression for Developed Torque: Singly excited electromagnetic relays have been analyzed using the principles of electromechanical energy conversion Expressions for electromagnetic torque have been developed. and the expression for the torque is obtained as The following are the implications of equation (1): 1. the rotor experiences a torque tending to move it to a minimum reluctance position corresponding to the new phase. In this position. The number of phases is m and each phase is made up of concentrated coils place on 2q stator poles. the rotor will be at rest in a position which provides minimum reluctance for the flux produced by that phase. The torque is proportional to the square of the current so.2 PRINCIPLE OF OPERATION With only one phase switched on. still unidirectional torque is produced.CHAPTER 2 SWITCHED RELUCTANCE MOTOR CONTROLLER 2. Now if that phase is switched off and another phase switched on. Most favored configuration amongst many options are 6/4 three phase and 8/6 four phase Switched Reluctance Motors’s as shown in the figure 2.1 CONSTRUCTION Switched Reluctance Motor has wound field coils of a dc motor for its stator windings and has no coils or magnets on its rotor. current can be in either direction. These two configurations correspond to q = 1(one pair of stator poles and coils per phase) but q may be equal to 2 or 3 also. Switched Reluctance Motors are made up of laminated stator and rotor cores with Ns=2mq poles on the Stator and Nr poles on the rotor. Both the stator and rotor have salient poles. This feature reduces the number of power switches in the converter and thereby makes the drive economical 3 . Whichever direction of movement offers the least distance to be moved by the rotor to reach the new minimum reluctance position is the direction of rotor motion.1. These results can be extended to the switched reluctance motor. hence the machine is referred to as a doubly salient machine. 3(a) and 2. It is understood that the inductance of a stator winding is a function of both the rotor position and current. The torque constant is given by the slope of the inductance vs.3 (b). a typical phase inductance vs. The direction of rotation can be reversed by changing the sequence of stator poles excitation. rotor position characteristic.3 THE RELATIONSHIP BETWEEN INDUCTANCE AND ROTOR POSITION Since the torque characteristics are dependent on the relationship between flux Linkages and rotor position as a function of current. rotor position is shown in Figure below 2. 4. For example.2. 2. 3. thus making it nonlinear. a simple equivalent circuit development for this motor is not possible.2 Four distinct inductance regions emerge . which is usually the case. The significant inductance profile changes are determined in terms of the stator and rotor pole arcs and number of rotor poles.5 for a desired phase current. the various angles are derived as: Figure 2. From Figures 2. it is worthwhile to conceptualize the control possibilities and limitations of this motor drive. Because of its nonlinear nature. it has a good starting torque. Since the torque is proportional to the square of the current hence. which is a simple operation. The rotor pole arc is assumed to be greater than the stator pole arc for this illustration. 3 Inductance profile 1. generation of electrical energy from mechanical input to the switched reluctance machine).4 Where βs and βr are stator and rotor pole arcs. The operation of the machine in this region results in negative torque (i.. This is very much similar to the θ1 − θ2 region. 4. motoring) torque. θ2 − θ3: During this period. in this region there is no torque production. This has the effect of keeping the inductance maximum and constant. but it has decreasing inductance and increasing rotor position contributing to a negative slope of the inductance region. and is the number of rotor poles. θ3 − θ4: The rotor pole is moving away from aligned stator pole in this region. 5 .e. This region comes to an end when the aligning of poles is complete. Figure 2. Hence. respectively.. This increases the inductance with the rotor position. 2. The inductance in this region is known as . θ1 − θ2: Poles are aligned. thus making the inductance minimum and almost a constant. 0 − θ1 and θ4 − θ5: The stator and rotor poles are not aligned in this region and the flux is predominantly determined by the air path. so the flux path is mainly through stator and rotor laminations. 3. movement of rotor pole does not alter the complete align of the stator pole and does not change the dominant flux path. giving it a positive slope. A current impressed in the winding during this region produces a positive (i.e. and this inductance is known as .It is not possible to achieve the ideal inductance profiles shown in Figure above in an actual motor due to saturation. At this position reluctance is minimum. βs and βr are stator and rotor pole arcs. Therefore the inductance of the coil is LA. Let us assume that βr > βs and LA >LU.4 Aligned Position CASE 1: When θ=0 Axis of the stator pole is in alignment with the rotor pole as shown in the figure 2.2. Figure 2.4(b) 6 . At this position flux linkage of phase winding of stator has maximum value and hence inductance of phase winding has maximum value for given current. Then the Figure 2.4(a).4 ALIGNED AND UNALIGNED INDUCTANCE Let LA be the aligned inductance of a coil/Phase and LU be the unaligned inductance of the coil / phase. respectively. because the stator reference axis and rotor reference axis are in alignment. Figure 2.4(a) of rotor pole is along the edge of stator pole. Therefore L < LA and L > LU.4(c) Figure 2. Figure 2.In this position. the flux pattern is such that the flux linkages / unit current of the stator is less than the previous case but not minimum.4(d) 7 . 5 Voltage PWM-Hard/Soft chopping Voltage PWM chopping can be realized in two ways with this drive topology. and therefore soft chopping was realized in this application.5 shows the difference and the phase current. Soft chopping is when only the high side power switch is chopping. flux linkage.Figure 2. It generally produces more electric noise. it also generates more current ripples. soft chopping and hard chopping. Figure 2.4(e) 2. voltage and inductance profile.5 TO OBTAIN THE CURRENT WAVEFORM Figure 2. the other switch remains permanently on. 8 . Hard chopping is when both transistors are switched on/off together. 6 General Motor Control Design The function of the components in detail: Main supply: Provides circuits energy. Figure 2. Driver: Switches the power necessary for the motor phases 9 .6 shows a schematic for general motor control design with a microcontroller. which ensures that a certain current value is not exceeded. Microcontroller power supply: Regulates voltage and current for the microcontroller Microcontroller: Produces the accurate signals for switching the MOSFETS also contains protection circuit.The Figure2. Figure 3. To achieve an approximation to this current.-Vs). The power converter topology has great influence on the Switched Reluctance Motor’s performance.1 POWER CONVERTER TOPOLOGY: As indicated by its name.2. Phase current then quickly decreases 10 .2 ENERGIZING THE SWITCHED RELUCTANCE MOTOR The Switched Reluctance Motor is energized using an Asymmetric Half Bridge Inverter shown in figure 3. As long as dR/dθ is negative. Rotor position feedback. or "sensor less" feedback method. There are three voltages that can be applied to the stator windings. This is a common topology used for this type of motor as it allows each phase to be energized independently.CHAPTER 3 CONVERTERS FOR SWITCHED RELUCTANCE MOTOR DRIVES 3. torque opposes motion and we switch off current in that phase. the phase winding will experience –Vs voltage.When Q1 and Q2 are off. Phase current then slowly decreases by freewheeling through Q1and D1. When dR/dθ becomes positive. the winding voltage will be zero.Control of speed is achieved by varying the magnitude of the phase voltage. which will be different. is needed for proper control. Switching Strategy: Switched Reluctance Motor’s are controlled by synchronizing the energizations of the motor phases with the rotor position. phase-to-phase switching in the Switched Reluctance Motor drive must be precisely timed with rotor position to obtain smooth rotation and the optimal torque output. Consider phase-A. torque will aid the motion and we would like to keep the current going.1 Variation of reluctance of the flux path of a phase The shape of this curve is decided by number of teeth on stator and rotor. It is well known that this phase-to-phase switching is realized by power semiconductors. we have to use PWM for supply voltage . the voltage applied to the phase winding is +Vs when the Q1 and Q2 are on (+Vs-Q1-phase a-Q2. Phase current then increases through both switches. If Q1 is off while the Q2 is still on. (Larger voltage larger current larger torque larger steady state speeds) 3. through both diodes (-Vs-D2-phase a-D1-+Vs).2 Half-Bridge Inverter 3. phase current of the Switched Reluctance Motor controlled. By appropriately coordinating the above three switching states. a dc voltage is used to switch on the phases in succession. 11 . Figure 3. 2) During the period a phase is ON. a) Current in it is assumed constant b) Its inductance is assumed to increase linearly 3) V vs.3 TORQUE SPEED CHARACTERISTICS OF A SWITCHED RELUCTANCE MOTOR 1) In a Switched Reluctance Motor. both of which are function of t. I equation while a phase is ON R‐resistance of coil Where =flux linkages of coil due to current φ is a function of rotor position θ and i(t). But for power balance. 12 .φ = ( θ. With I constant at Irated. power input increases. If we keep increase V such that ‘i’ is Irated. neglect induced emf. torque will decreases.i) Transformer rotational Emf Emf If we assume i(t) is a constant. EMF increases. supply voltage cannot be increased any more. So current will decreases. while developed torque is constant at Td.Beyond that speed. Td=constant= KIrated2. This continues till a speed called base speed is reached . V=R i(t) 5) Low Speed Operation: Because of low speed. Figure 3.3 Torque Speed Curve for a Switched Reluctance Motors 13 . 14 . void main() { int i. pulse4=1. pulse1=0. sbit pulse2=P2^0.CHAPTER 4 SOFTWARE CODE //Program for switching the MOSFETS using AT89S52 #include<reg51. while(1) { for(i=1. delay1(). pulse2=0. sbit pulse5=P3^7.i++) { pulse=1. void delay(). sbit pulse4=P3^0.h> sbit pulse=P1^0. pulse5=1. pulse3=0. pulse1=1. sbit pulse3=P2^7. void delay1(). sbit pulse1=P1^7.i<=3. pulse1=0. pulse1=1. pulse3=0. delay1(). pulse2=1. pulse5=0. pulse4=0. pulse4=0.i<=3.i++) { pulse=1. pulse3=1. pulse1=0. pulse3=0.pulse5=0. pulse5=0.i++) { pulse=1. delay1(). pulse1=1. pulse2=0. } for(i=1. } 15 . delay1(). delay1(). delay1().i<=2. } for(i=1. i<=3. pulse4=0.i++) { pulse=0.i++) { pulse=0.for(i=1. pulse2=1.i<=3. delay1(). pulse5=1. delay1().i++) { 16 . pulse3=0. } for(i=1. delay1().i<=2. pulse3=1. } for(i=1. pulse5=0. pulse3=1. pulse1=0. pulse1=0. pulse4=1. pulse3=0. pulse5=0. pulse2=1. delay1(). while(TF0==0).pulse=0. pulse5=0. delay1(). TR0=0. TH0=0XFD. pulse5=1. pulse2=0. } 17 . TF0=0. pulse1=0. pulse4=1. pulse3=0. } } } void delay1() { TMOD=0X01. TL0=0XC0. TR0=1. delay1(). 2) Full wave rectifier circuit. The outputs from the secondary coil which is center tapped are the ac values of 0v. 5) Output filter. Regulator unit: Regulator regulates the output voltage to a specific value. The most important and simple device used in rectifier circuit is the diode. 6) Indicator unit.1. the dc voltage also changes. as the various devices used in this project require reduced voltages. 4) Voltage regulators.1 POWER SUPPLY SECTION 5. The output voltage is maintained irrespective of the fluctuations in the input dc voltage. 15v and-15v. Step down transformer: The step-down transformer is used to step down the supply voltage of 230v ac from mains to lower values.1 Power Supply to the Microcontroller Figure 5. Whenever there are any ac voltage fluctuations.CHAPTER 5 HARDWARE DESCRIPTION 5.1 Power supply Circuit for microcontroller Power supply block consists of following units: 1) Step down transformer. The simple function of the diode is to conduct when forward biased and not to conduct in reverse bias.The conversion of these ac values to dc values is done using the full wave rectifier unit. 18 . Rectifier Unit: The rectifier circuit is used to convert the ac voltage into its corresponding dc voltage. 3) Input filter. is needed for proper control topology has great The most common approach to the powering of a switched reluctance motor is to use an asymmetric bridge.7805 which provides 5v dc 2. the voltage applied to the phase winding is +12V when the Q1 and Q2 are on (+Vs-Q1-phase a-Q2. 19 . Rotor position feedback or “sensor less” feedback method. Capacitors used here are of value 10UF. phase current of the Switched Reluctance Motor controlled. Figure 5.2 Power Supply Circuit for Switched Reluctance Motor Operation: This is a common topology used for this type of motor as it allows each phase to be energized independently. Consider phase-A. If Q1 is off while the Q2 is still on.When Q1 and Q2 are off. the winding voltage will be zero. 5. Phase current then slowly decreases by freewheeling through Q1and D1.-Vs). the phase winding will experience -12V voltage.7812 which provide 12v dc Output Filter: This filter is fixed after the Regulator circuit to filter any of the possibly found ripples in the output received finally. phase to phase switching in the Switched Reluctance Motor drive must be precisely timed with rotor position to obtain smooth rotation and the optimal torque output.1. Phase current then increases through both switches.2 Power Supply Circuit for Switched Reluctance Motor As indicated by its name. Phase current then quickly decreases through both diodes (-Vs-D2-phase a-D1-+Vs). By appropriately coordinating the above three switching states.Regulators used in this application are: 1. o cycle into o fourteen parts. 20mH of inductance as a shown bellow.1 SWIT TCHING G FOR MOSFET T We considerr a circuit haaving a 10ohhm resistancee. We divide one A t=0.CHA APTER R6 EMATIC C CONN NECTIO ONS SCHE 6. sw At witch is at position 2 20 . 23 9.Time Periods T1 T2 (m sec) 2.1 2.1Pulses for MOSFET Q1 6.87 6.54 16.1.23 6.05 5.52 80 6.09 5.82 12…03 1.1 1.2Pulses for MOSFET Q2 21 .1.56 4.93 2.93 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 3. 1 Current Waveform 22 .6.2 SWITCHING CIRCUIT OF SWITCHED RELUCTANCE MOTOR FOR SINGLE PHASE 6.2. 3.1 Current Waveforms 23 .3 SWITCHING CIRCUIT OF SWITCHED RELUCTANCE MOTOR FOR TWO PHASE 6.6. 4 SWITCHING CIRCUIT OF SWITCHED RELUCTANCE MOTOR FOR THREE PHASE Figure 6.6.1 Switching circuit of Switched Reluctance Motor for three phases 24 . 2 Current waveform across three phase winding 25 .1 Current Waveforms Figure 6.4.6. 6.m2 Friction : 0.01 Ohm/phase Inertia : 0.0082 Kg.5.7mH Aligned Inductance : 20mH Maximum Current : 450A Maximum Flux Linkage : 0.1 Specifications of Switched Reluctance Motor: Stator resistance : 0.3 Circuit connections in MATLAB 26 .5 SIMULATIONS IN MATLAB SOFTWARE 6.486 Weber-turn Figure 6.01N m s Initial speed : 0 rad/sec Position : 0 rad Unaligned Inductance : 0. 4 Switched Reluctance Motor characteristics in MATLAB simulation 27 .5.2 Switched Reluctance Motor Characteristics in MATLAB Figure 6.6. 6.6.6 EAGLE DESIGNS 6.6.2 Board Layout of Power Supply Circuit 28 .1 Schematic Layout of Power Supply Circuit 6. Hence we have find out the inductance range i.1 Simulation in Proteus Here the inductance value is 5mH and this is the current waveform which is not accurate.6..3 Schematic Layout of Driver Circuit 6.e.7 DIFFICULTIES ENCOUNTERED DURING SIMULATION 6.6.7. 15mH to 30mH with resistance of below 20Ώ 29 . 30 . the speed oscillates continuously and after certain time period it oscillates in the negative direction.2 Simulation in MATLAB Current and Speed Waveforms This is for the frequency of 200Hz.7. For which the motor stops running.6. The best way to do this is to use a dedicated MOSFET driver chip. By appropriately coordinating the above three switching states.CHAPTER 7 HARDWARE IMPLEMENTATION 7. one inductor of 20mH with 1ohm internal resistance is considered as one phase winding of the motor. The effect of this is that when the pulse to the gate terminal arrives.where as MOSFET Q1 is continously on. 7. the phase winding will experience -12V voltage.-Vs). Phase current then slowly decreases by freewheeling through Q2and D2. when the MOSFET Q1 and Q2 are on (+Vs-Q2phase winding-Q1. The gate terminal then effectively does take current.After that the two MOSFETS should be turned off for some period.The MOSFET Q2 is on and off for eight times. the gate terminal must be set to a voltage at least 15 volts greater than the source terminal. it must first charge this capacitance up before the gate voltage can reach the 15 volts required. If MOSFET Q2 is off while the Q1 is still on. Therefore the circuit that drives the gate terminal should be capable of supplying a reasonable current so the stray capacitance can be charged up as quickly as possible.One feature of power MOSFETs is that they have a large stray capacitance between the gate and the other terminals.2 DRIVER CIRCUIT The Driver circuit is used to turn on MOSFETS. Phase current then increases through both switches. the voltage through phase winding will be zero. The current through phase winding quickly decreases through both diodes (Vs-D1-phase a-D2-+Vs). two diodes.1 POWER SUPPLY CIRCUIT The power supply circuit consists of two IRFZ540N mosfets. phase current of the SWITCHED RELUCTANCE MOTOR can be controlled.And then the cycle repeats.When Q1 and Q2 are off. 31 . In this way the MOSFETS are on. It is designed in such a way that the ports should be on/off at appropriate times. These pulses are giving to MOSFETS. 32 .This is the driver circuit we are using for switching the MOSFETS.74LS 40 IC an TLP250 IC are used in this circuit. 7.3 MICROCONTROLLER CIRCUIT The microcontroller is embedded with a C program.The pins used in microcontroller are connecte to input pin of 74LS 40 IC. The output is checking with an oscilloscope. then this is connected to output pin.At this pin voltage is step up.That output Voltage is given to the gate terminals of the MOSFET. 4 INTERFACING MICROCONTROLLER WITH DRIVER CIRCUIT The pins used in microcontroller are giving to the inputs of driver circuit. The 8051 architecture developed by Intel has proved to be the most popular and enduring type of microcontroller.then the output pins of the driver circuit is giving to the gate terminal of the MOSFETS. By some estimation. 33 . and robotics as well as in the automotive industry. 8051 family chips make up over 50% of the embedded chip market.8051 chips are used in a wide variety of control systems. telecom applications. available from many manufacturers and widely used for industrial applications and embedded systems as well as being a versatile and economical. 7. 5 COMPLETE CIRCUIT TESTING Checking the current waveform across the phase winding (inductor of 20mH). the probes of oscilloscope are put across the resistor.1 Current waveform 34 . The current waveform is as shown below. 7.Here we are connecting a 10ohm resistor in series with an inductor.5. The output is seen in the oscilloscope.7. 1 First Difficulty We have considered secondary winding of the transformer.7. rating of 15v-0v-15v.6. due to this reason the required waveform is not obtained. 500MA L=62.6 DIFFICULTIES ENCOUNTERED ON HARDWARE: 7. The current waveform looks like this 35 . The resistance value is very high.5mH with internal resistance of R=65 Ω. 6. the inductance of the core coil 1mH and resistance is 140 ohms.2 Second Difficulty We have considered an rectangle core material. and we have turned 200 turns.7. which is not sufficient to get the required waveform. The current waveform looks like this 36 . Switched Reluctance Motor characteristics are verified. --->The hardware kit is tested successfully by embedding the C program – Hex file in the AT89C51 Microcontroller. ---->Connections in MATLAB software are studied.CHAPTER 8 CONCLUSION AND SCOPE OF FUTURE By the end of this project ---> Switched Reluctance Motor Characteristics are studied. In future. --->Hardware implementation by connecting Schematic and making Board layout EAGLE is done successfully. Even the speed control of Switched Reluctance Motor is to be verified. when motor is available the same pulses are given to the MOSFETS through a driver circuit and the output current waveform is observed. --->Connections and testing in Proteus is studied. --->Coding and compiling of a C program in Keil u Vision software is studied. --->The operation of microcontroller is analyzed in simulation and practically. Scope of the Project: We have considered an inductor as one phase winding of the motor. 37 . com/proteus [6] A K Ray.wikipedia.pdf [4] Michael T.ti.google.isis.DiRenzo.com/8051 [2] Website: www. 38 .com/lit/an/spra420a/spra420a. [5] Website: www. “Microprocessor and Microcontroller”.com/eagle_software [3] Website: http://www.REFERENCES [1] Website: www. “Switched Reluctance Motor Control”. Virtual System Modeling lets co simulate embedded software for popular microcontrollers alongside hardware design. rip-up and retry auto-router and interactive design rule checking. Microcontrollers. PROSPICE Mixed mode SPICE simulation . System Benefits Integrated package with common user interface and fully context sensitive help. Electromechanical devices etc. System components ISIS Schematic Capture . 39 . VSM .a tool for entering designs.PCB design system with automatic component placer.industry standard SPICE3F5 simulator combined with a digital simulator. ARES PCB Layout .APPENDIX A SOFTWARE USED – PROTEUS It is used for the real time simulation of the Circuits involving complex ICs. IDE.APPENDIX B SOFTWARE USED – KEIL uVISION Keil was founded in 1986 to market add-on products for the development tools provided by many of the silicon vendors. Keil implemented the first C compiler designed from the ground-up specifically for the 8051 microcontroller. Keil provides a broad range of development tools like ANSI C compiler. library managers. 251. ARM. linkers. debuggers and simulators. assemblers. COMPILING A ‘C’ PROGRAM IN KEIL 40 . and XC16x/C16x/ST10 families. real-time operating systems and evaluation for 8051. It is for the platforms Microsoft Windows. Schematic and Board Layout in EAGLE 41 . It exists for non-commercial use. a free version on a schematic sheet. half Euro card mm × 80 mm and two signal layers is limited to 100. Linux and Mac OS X available. The software consists of several components: Layout Editor. Cad Soft Eagle and the company in September 2009. Schematic Editor.APPENDIX C SOFTWARE USED – EAGLE EAGLE is an EDA program by Cad Soft for creating printed circuit boards. The name is an acronym formed from Easy Applicable Graphical Layout Editor. The schematic editor can be used by a special component library for programming a MicroSPS is used. Auto router and an extensible component database. Premier Farnell sells a supplier of electronic components. Performance of MATLAB scripts can be improved using vector operations (more on this later).APPENDIX D SOFTWARE USED – MATLAB A high-performance language for technical computing (Math works. Everything MATLAB understands is a matrix (from text to large cell arrays and structure arrays) .MATLAB has advanced data structures including object oriented programming functionality and over loadable operators. 42 . 1998).Various data types exist within MATLAB. MATLAB works with matrices. APPENDIX E DATA SHEETS 43 . 44 . 45 . 46 . 47 . 48 . 49 . 50 . 51 . AT89S52: 52 . 53 . 54 . 55 . 56 . 57 . 58 . 59 . 60 .
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