Kontrola Excitationê ya Machineya Synchronous bi Karîna Chopper
Naverok
Kamciyekarîna Makîneyê Sênkron Bi Karbûrên Chopper
Dibeşkirina Berdewambera Makîneyê Sênkron Bi Karbûrên Chopper
Pêşketina Kamciyekarîna Makîneyê Sênkron Bi Karbûrên Chopper
Bijarkên Serke:
Taybetmendîya Kontrolê Excitation: Taybetmendîya kontrolê excitation ya li makîneyê sênkron dike ku têne bikin biguherîne performansa we bi guherandina çavkanina DC field.
Prinsîp Kamçiyekarî: Prinsîp kamçiyekarî ya makîneyê sênkron bi karbûrên chopper ya li vir û kontrolkirina wê bi nîşaneyên PWM bidekîne bi rêza excitation a heta dixwazî.
Zelalên Karbûr: Karbûrên bi karbûrên chopper ji bo kontrola excitation yê tevgeriya zelal, mezîn, kontrolê çaw, û pêşdestina çax îne.
Bilezanên Di Çavkarê Chopper de: Bilezanên ên derbasdaran in: MOSFET, nîşanka pulse width modulation, rectifier, capacitor, inductor, û bilezanên parastina wêchîn kama MOV û fuse.
Dibeşkirina Dindar: Dibeşkirina dindar dikare bide kirina kontrola loop bendî ji bo barkên girtî û bilezanên tevlî yên bikin performansa bêzde û herîna tîrîn bêde.
Makîneyê sênkron yek makînê elektrikî yekêmî ye ku di çend şopên de hatiye bikar anî, wek hesabkirina rastî, dayinên serbest û perhezkariya faktora guhertinê. Faktor guhertinê dike bikin biguherîne bi guherandina çavkanina DC field. Ev tezkerat li ser çawa me dikarin kontrol bike çavkanina field ya makîneyê sênkron.
Rêzikên DC excitation destpêk dikin piştgiriya û parastina pirseman dikin serûs, fırçalar, û kommutators, paqeydigir li serberê alternator ratings bergevin. Sisteman modern excitation dikin biderbarêne wan pirsemanan bi guherandinê tevnayan da contact û fırçalan.
Ev tendîsa hatiye vegerîna excitation statîk bi karbûrên chopper. Sisteman modern bikin wergerandina semiconductor switching bilezanên wek diode, thyristors û transistors. Di elektronîkê guhertinan de, dar hejmar zêde ya energya elektrikî hatiye guhartin, converterên AC/DC yê hilbijartin.
Rêzikên power hatiye digerîn ji hazirên dekên ta hazirên çend hezar watt. Di industrî de, birkarî ekidî ye motorka induction ên bikeribin kontrol bike çêtî.motorka induction. Sisteman guhertina power hatiye navkirin bi input û output power types.
AC to DC (rectifier)
DC to AC (inverter)
DC to AC (DC to DC converter)
AC to AC (AC to AC converter)
Ev li ser pirûs û statîk malperên biafirandina, berdewam û bikaranîna mîqdara zêdetir energya elektrikî. DC-DC converter yek circuit elektronîkî ye ku energya direct current ên jî bidekîne ji voltage level ên din bivîne level ên din.
Zelalên converterên electronic power in:
Efficiency bêzde ji ber bi rengin ên zêd în power semiconductor devices.
Reliability bêzde ya sisteman converter electronic power.
Cih û parastina kam ji ber absenseya malperên tevnayan.
Flexibility û operasyon.
Pêşdestina çax û dynamic response bêzde ji ber electromagnetic converter system.
Hilweha zêdetir nekin converterên electronic power wek:
Circuit ên power electronic system dikin harmonic generate di supply system de û load circuit.
AC to DC and DC to AC converter operate at low input power factor under certain operating condition.
Regeneration of power is difficult in power electronic converter system.
Di proje de, voltage average di field ên makîneyê sênkron de dikin kontrol bike bi boost chopper. Boost chopper yek DC to DC converter ye ku dikin provide voltage output controlled bêzda ji fixed input DC voltage.
MOSFET yek device semiconductor electronic power ye ku fully controlled switch (a switch whose turn on and turn off both can be controlled). MOSFET is used as the switching device in this Boost chopper circuit. The gate terminal of MOSFET is driven by a pulse width modulation (PWM) signal. Which is generated by using a microcontroller. The supply voltage of the chopper has been taken from a diode bridge rectifier by conversion of single phase AC/DC.
This scheme of field excitation control is extremely efficient and compact sized, due to the involvement of power-electronic circuitry. In many industrial applications, such as reactive power control, power factor improvement of transmission line it’s required to change field excitation.
This drive take power from fixed DC source and convert it to variable DC voltage. Chopper systems offer smooth control, high efficiency, faster response and regeneration facility. Basically a Chopper may be considered as DC equivalent of an AC transformer since they behave in an identical manner. As chopper involves one stage conversion, these are more efficient.
Kamciyekarîna Makîneyê Sênkron Bi Karbûrên Chopper
To understand details of project plan let’s consider this block diagram below:
From the above diagram we can say that for 230V input of a full wave rectifier the output voltage is 146 (Approx.) the field voltage of the machine is 180V so we have to step up the voltage though the step up chopper. Now the adjusted DC voltage is fed to the field of the synchronous machine. The output voltage of the chopper can be varied by changing the duty cycle to do so we have to make a pulse generator of adjustable pulse width, and this can be done with help of a Microcontroller.
In microcontroller by comparing a random sequence signal with a constant magnitude we can generate a pulse signal but to avoid loading effect it’s advisable an electrical isolation to do this we are using an Opto coupler. A capacitor has been used in the chopper circuit in order to remove the ripple from the output voltage. It has been simulated that the inductor which has been used in the chopper circuit should be capable of handling 2-3 A of current during the short circuit period. Apart from the desired output voltage, we should also design the circuit so that it can withstand any fault condition.
For overvoltage protection, we will use a metal oxide varistors (MOV) whose resistance depends upon the voltage.
For overcurrent protection, we can use first acting current limiting Fuse.
To improve the quality of the waveform we can use filter circuit basically L or LC filter at the output of the bridge rectifier. The diode which has been should have less reverse recovery time here we can use fast recovery diode.
Values of circuit components that have been used
Input DC Voltage = 100V
Pulse voltage = 10V, Duty = 40%
Chopping frequency = 10 KHz
R = 225 ohm (As calculated from the machine rating)
L = 10mH
C = 1pF
Data obtained from the output
Output voltage: 174 V (Average)
Load current: 0.775 A (Average)
Source current: 0.977 A
Dibeşkirina Berdewambera Makîneyê Sênkron Bi Karbûrên Chopper
There is still much room for future development that would enhance the system and increase its business value.
Closed loop control
Application areas where the user deals with variable load, needs a closed loop control scheme to maintain constant excitation. Reference voltage and actual output voltage will be compared first and an error signal is generated. This error signal will decide the duty cycle of the chopper.
Reduction in temperature effect
Use of precision capacitor, switching diode can definitely improve the performance, but they will aid to the cost of the project.
Pêşketina Kamciyekarîna Makîneyê Sênkron Bi Karbûrên Chopper
In our project, we designed and implemented a low-cost and user-friendly excitation controller using Chopper. The target users of the system are industries requiring smooth, efficient and small controller which gives a wide range of voltage variation. This type of project is really useful in the industrial fields of developing countries like India, where energy crisis is a great concern.
We have learned much through the project. We got the lesson of team work, co-ordination, leadership while going through various phases of development of the project. We were challenged by the complexity of the technologies needed to build the system. This helped us to co-relate and apply the theoretical knowledge we obtained in engineering course.
None of us had experience with electronic control of motor before the project. We needed to learn different concepts and techniques quickly and apply them in the system. The project also provided a chance for us to accumulate experience in pulse signal generation and power MOSFET control area. This project experience has greatly enriched our knowledge and sharpened our technical skills.
