Principle Of Operation Of Switched Reluctance Motor Engineering Essay

Principle Of Operation Of Switched Reluctance Motor Engineering evidence1. INTRODUCTIONFrom those days the variable star quantity falter rams had played a spanking role in galvanising field. These motors be very attractive because they feature replaced conventional ac and dc devolve ons in m whatsoever a(prenominal) industrial applications solely oer the world. Apart from the working they charter many advantages such as elementary and low cost construction. Since the variable hesitance motor has a laid-back tortuosity with the inertia ratio normal when comp ard with other motors. ultimately the single head salient synchronous hesitation motors clear most advantages which are similar to variable reluctance motor. The cost and performance of the mechanism is highly low-level on the converter topology. The converter for the political machine get down should be very fast accurate sacrifice-day(prenominal) examine for dampen carry performance. In supplemen t to these sine qua nons the machine should produce low atomic take 23 ampere military rank for low cost, should be more reliable and square-built with small number of bewilderes producing high efficiency at last.In increment to this all of these converters have greater transmutation loss and stress because the converters are all operated with hard switching. Now a days soft switching is in addition implemented for these types of machines. The in a higher place mentioned goals can be achieved every by improving the machine visualize or innovation in the inverter bod. I hope that my purpose deals with the application of a particular type of inverter for the variable reluctance motor drive.2. VARIABLE reluctance force back DRIVES2.1 CONSTRUCTIONThe prefatory construction of switched reluctance motor is shown in the figure. The construction includes many(prenominal) stator and rotor coil. It has six pole rotor and eight pole stator in it. The conventional variable rel uctance motor that is nothing but the switched reluctance machine has a doubly salient laminated structure which is very simple and robust. The rotor does not contained any hints or conductors within it.2.2 PRINCIPLE OF subprogram OF SWITCHED RELUCTANCE MOTORTo start with the switched reluctance motor, the torque production in the machine is explained with the help of principle of electromechanical energy produced in the ringlet of the machine. As the rotor rotates, the inductance of the manikin windings of a machine varies amidst the inductance values with respect to the rotor angle. Due to the highly non bilinear magnetic deportment of the variable reluctance motor, the signifier inductance is dep finisent on the on press release level as wellhead as with the rotor position. There is everyplacely a speed dependent back electromotive force that becomes very large below and above the etymon speed and dominates the behaviour of the drive. Although the machine has a simp le structure, the behaviour of its electromagnetic is obviously convivial. The electrical input energy is given by expression which is displayed as followsHowever, the linear inductance of switched reluctance motor model along with back emf. And excessively the back emf is proportional to the machine speed which is very stabilizing in exploring the behaviour of this type of drive .The diagram of solenoid coil and the characteristics of the machine is shown as belowFor low-speed ope judge mode, the back emf can be ignored in such a oxygenise that these can be compared with the dc bus voltage, and the machine can be assumed as legitimate fed driving machine. Current fed deed is obtained by means of a incumbent regulated pulse rate width passage technique. With a proper controller and converter, the phase menses should be knowing to be close to a square waveform in redact to minimize torque pulsations. The back emf increases for the medium speed rank machine . To compensat e the loss, phase is excited al prepare in juting of the waveform .The machine runs at speed below and above the base speed. here the back emf is compared and in any case the emf is even big than the hang on voltage than that of the phase current. thus the phase current becomes unimaginable without very large advanced techniques. The phase winding should now be excited before , whereas its inductance value is small in modeicalness to develop the sufficient current for a challenging torque. During this mode of carrying into action the phase winding is fed with the voltage and hence the technique is called pulse dropping mode. Even at any able author electronic converter or the controller, this type of drive system must follow the capability of the design for the current pulses to chief(prenominal)tain the values of variable reluctance motor accurately.The above mentioned waveforms are executed by simulation method with the help of the mat lab software. The mat lab code f or the above mentioned waveform is as follows3.MATLAB SIMULATION3.1 CODING 1w=1k= zip fastenersd=0z=zerosi=0t=0e=0.000001 % is the increment of term art object (tif t time iz(w)=t % to inventory the time valuesk(w)=i % to store the current valuesd=(1/0.1)*(100-(10*i))*e % is the increment of currenti=i+d % to increase the currentt=t+e % to increase the timew=w+1 % to increase the ability of the current and time wandersend bandage i=6.5while i=6 % to qualify the current to a lower limit of 6z(w)=tk(w)=id=(1/0.1)*(-(10*i))*ei=i+dt=t+ew=w+1 endendendift0.03z(w)=tk(w)=id=(1/0.1)*(-100-(10*i))*ei=i+dt=t+ew=w+1 endift=0.0353 markendendplot(z,k,r-,LineWidth,2,Color,black)OBTAINED WAVEFORM3.2 CODING 2v= % an array to store the value of voltagesp= % an array to store the value of timec= % an array to store the value of the currentsR=1 % metro valueL=0.001 % inductane valuefs= kibibyte000 % sampling frequencyf1=1000 % switching frequency of the 1st switchf2=142.857 % switching frequency of the second switchd=0.5 % duty cyclet_on=d*(1/f1) % t ON for the 1st switchdi=0n=0x=0i=0t=0t2=(1/f2)while twhile (tn=n+1v(n)=50di=(1/L)*(v(n)-(R*i))*(1/fs)i=i+dic(n)=ip(n)=tt=t+(1/fs)endx=x+(1/f1)if (twhile tn=n+1v(n)=0di=(1/L)*(v(n)-(R*i))*(1/fs)i=i+dic(n)=ip(n)=tt=t+(1/fs)endendendwhile t=(0.5*t2) % the second half cycle of the second switchn=n+1v(n)=-50di=(1/L)*(v(n)-(R*i))*(1/fs)i=i+dic(n)=ip(n)=tt=t+(1/fs)if c(n)breakendendplot(p,v), axis (0 0.005 -50 55)hold onplot(p,c)hold offXlabel (Time)Ylabel (Current / Voltage)OBTAINED WAVEFORM4.CLASSIFICATION OF SWITCHED RELUCTANCE MOTOR5.MODELING AND CONTROL STRATEGIES OF A VARIABLE RELUCTANCE MOTORThe above block diagram represents the imitate of the variable reluctance motor with their control strategy. The above circuit contains the adjacent blocks such as run through prior compensator, integrate or current controller and the driver block. The block also contains the observer. The feedback from the motor or drive is connecte d to the observer as well as to the feedback compensator. The machine is designed in such a way that it is based on two synchronous and asynchronous type and in this machine the torque control job can be solved by transforming it into an equivalent current control one.The simple solution is probable because the torque is proportional to the current or to a specific component of the current vector in a proper orientation system. Moreover by considering the wide accessibility of high-quality and low-cost current transducers the solution obtained is also more convenient from an scotch lay of view. For the variable reluctance motors the torque versus current function is nonlinear and thusly preventing the simple solution which adopt these drives for standard motors.To prevail over the problem a cascade controller structure which is same as the one proposed earlier has been selected. It consists of an external static feed beforehand nonlinear compensator which is followed by a nonl inear flux or the current which is selected depending on design choices with the closed- curl up controller. In the case of feed forward compensator transforms the torque tick point which is corresponding to the flux or current is normal in these cases. The innate closed-loop controller is based on exact or straight measured feedback, depending on the controlled variable selected. Hence the optimization techniques are utilise for the design of a feed forward pre compensator.The closed-loop controller operates in a stator reference frame thus by avoiding the use of reach up transformations. This designing presents the inverter for the motor pattern and control optimization activities. splendor is placed on the optimization techniques used in the design of the feed forward compensator. Finally the work related to the design of the closed loop flux or the current controller is currently in growth. The main report here is that the consecrate to validate the design of the feed fo rward compensator. Previous to entering into details about the feed forward compensator design, some general considerations are value making in this resistant of this design. maneuver calculation of a current set point is not sufficient because the torque reliance on current must also designate about magnetic nonlinearities. Even though the simpler relationship exists betwixt torque and flux the feed forward compensator is designed under the assumption of an internal flux closed-loop controller. But the current is certain in such a way that the flux set point can be this instant transformed into a current by means of the model re travel obtained. It must be pointed out how the planned replica structure would be greatly simplify the design of the torque controller.A critical point is the alteration of the scalar torque demand into a corresponding three-phase flux vector. It can be noted that fluxes qualified to contrasting phases can be bewildered independently by means of the associated control inputs. The control problem thus has as many degrees of independence as the figure of phases. These degrees of freedom can be used for different purposes such as the four-spot phase motor and the two adjacent phases. These are selected according to the certain rotor position and torque signal that are used to jaw torque dynamics and ripple-free operation.The remaining two phases are controlled in order to wield their current at zero. For a certain phase motor, the mandatory dynamics is obligatory on motor acceleration by exacting a single phase and thus by selecting as a function of position and torque sign. The left over controls must keep the remaining phase currents at zero or collect them to zero as fast as practicable. Both approaches have the similar kind of problems mainly related to the need for a fast switch-on and switch-off of phase currents that chatter a voltage waveform that is strongly impulsive. art object the voltage is modified in a rea l causation inverter there is an increase in the enduring torque ripple occurs in the machine. Furthermore the solution proposed in during the good dynamic specification of the error between the actual and the craved acceleration does not control the torque ripple explicitly. The approach which is going to be considered in this attempt many degrees of freedom as possible in order to get the best performance from the motor. Thus the modelling would be through with(p) in such a way that it gives high efficiency with the low cost production.6.OVERVIEW OF A VARIABLE RELUCTANCE MOTOR TOPOLOGYThe performance and cost of the variable reluctance motor drive is highly dependent on the topology used to drive the machine. Since the features of variant reluctance motor drive have been realized the developments in the topologies have proceeded in parallel with the machine design. From those days there have been many topologies invented and while the conventional inverter driven proof machine drive the variable reluctance motor drives havent been made standard . In addition to this the foundation motor drives which some always carry an pulse width flexion voltage link inverter .This method for variable reluctance motor drives seems to be much more application dependent. Ideally the variable reluctance motor drive should meet the following requirementscapability to program a commanded current pulse very quickly and accurately for good drive performance. minuscule noise and torque pulsation.as low a converter power VA rating as possible for a given drive rating for low cost.low switch/phase ratio.reliability and robustness.high efficiency. unless if all the above requirements are met then only variable reluctance motor drives can be comparable with the conventional inverter driven induction machine drive and other variable speed drives that are present in the market. These topologies discovered up to date and these materials have become public and it is used in a many of the applications now a days. These configuration design include the asymmetric bridge converter with bifilar winding configuration which will split provision configuration from H-bridge configuration and also from the common switch configuration.The asymmetric bridge converter has an entire current pulse programming power in such a way that the converter is able of apply the full return voltage across the winding in either directions for the purpose turning the current in each phase that is in on state as well as in off state. Even though the converter faces some difficult from high switch or phase ratio it is commonly expensive because the two switches per phase and the associated drive circuit.The winding present in the machine that is the bifilar winding should meet the minimum switch requirement with one switch or the phase ratio. Thus the voltage waveforms resulting from non unified magnetic coupling will increase the switch voltage rating values to twice the value of t he voltage and even higher. In addition to the losses such as copper loss which is associated with the auxiliary windings are generally high for many applications.Thus the supply converter topology also meets the minimum switch requirement. And also in this case the phase number must be even and the converter does not ready to tolerate the phase unbalance or the fault in any phase. This is because these fault results in the voltage increase in the electrical capacity banks. And also the dc bus voltage utilization is poor because only 1/2K is utilized. Thus the H-bridge topology meets the minimum switch requirement. Therefore this reason is suitable for four or multiples of four-phase machines, and it also utilizes only half of the dc supply voltage. In this topology two phases are always on at one time and only one of the two phases are contribute to motoring torque production at any instant time.Therefore, the abjection of the return torque is achieved easily. The common switch design in the machine only requires one more switch in addition to the minimum switch requirement. However this does not tolerate phase overlapping and therefore this leads to its capability and also this is very limited because for the particular reason for the single-pulse mode. Here in this method they have already used C-dump configuration design and this configuration design also requires only one additional switch to the one switch or the phase requirement.The converter utilizes a capacitor to dump the energy of a switch off going phase and a chopper operating with buck principle to discharge the capacitor value. The capacitor voltage is generally maintained at twice the supply voltage value in order to supply negative supply voltage to the off going phase. The converter also has full capability to develop the current pulse during both turn on and turn off condition and also produces high efficiency operation results at the end. The main disadvantages of this converter are t he high switching device voltage ratings.The cost of the additional switch of the dump capacitor and inductor also matters finally with the losses associated of the reactive elements. To open new application handle to the variable reluctance motor drives it is clearly necessary to both mitigate the drive performance at the lower cost. These goals can be achieved either by improving the machine design or creating some innovations techniques in the Inverter which we are going to design. The general circuits for the converter topology are shown as followsThe force production for motoring and regeneration waveforms is shown in the upcoming figure.The forward direction of the inquiry of the translator is considered as the positive sign. The direction of the motion is considered as positive by assuming the certain phase sequence. While considering the forward direction of the motion they represent the forward motoring operations for their corresponding quadrants. Similarly when we are considering the reverse direction these regions represents the reverse regenerative operation for their quadrants. The duty cycle of each phase is only about 0.34 and their generate emf are constant between x1 and x2.The air gap power and the generating electromagnetic force can be made constant by exciting the stator phases with the wide range of pulse of currents. The one half of the air gap power is saved in the phase windings in the form of magnetic field energy. Then the mechanical power output is formed from the other half of the air gap power. There is the similarities between the reluctance motor and brushless DC motor in terms of current, air gap waveforms. Thus the dc machine controller can be used to control the switched reluctance motor for low cost and as well as for high volume applications.7.ADVANTAGES OF A VARIABLE RELUCTANCE MOTORSimple and robust in construction.Low cost due to the absence of rotor windings and magnets due to the use of a small number of concentr ated stator coils which is same as the field coils of a dc machine.Low rotor inertia and high torque.Motor phases operate almost independently to each other.The machine has greater economy and reliability.Machine does not need bi directional currents.Suitable for high speed operations.8.CONCLUSIONThus I hope that the back ground reading for my project has been done fully with the materials provided by our supervisor as well as with the materials we have collected. Future work is to design an inverter for a variable reluctance motor and build up the hardware kit for the operation. For the above mentioned reason I have gone through back ground reading holy related to the switched and variable reluctance motors. Thus my reason for taking over my project is for both modelling and building the hardware is to simplify the design of the high performance inverter for the machine with high efficiency. Even though different approaches had been overcome to design an inverter the process is ca rried out to design the material for both rotating and linear machines. Up to date the designing of the material in the testing ground had been performed by simulating using the Mat lab software and coding and waveforms obtained are displayed above in our report.