These can be distinctively classified as rotor resistance control and rotor impedance control. A different behavior is obtained for constant rotor current control. Usually yconnected, the ends of the three rotor wires are connected to 3 slip rings on the rotor. Wound rotor induction generator an overview sciencedirect. Induction motor solved problems pdf anthony begley productions. Pdf 1 a threephase induction motor is basically a constant speed motor. What has got me scratching around is the fact that 8 of the 10 speed selections. In small motors, this winding is normally of cast aluminum and consists of multiple conductors, or rotor bars, cast into the slots in the rotor core and joined at both ends of the stack with end rings. In the rotor side, other two methods are used to control the speed of the induction motor. The induction motor or asynchronous motor always relies on a small difference in speed between the stator rotating magnetic field and the rotor shaft speed called slip to induce rotor current in the rotor ac winding. Where speed control or frequent reversing is desired, or where high. Keywords wound rotor induction motor, matlabsimulink, rotor resistance method, slip power recovery method. In small motors, this winding is normally of cast aluminum and consists of multiple conductors, or rotor bars, cast into the slots in the rotor core and joined at. Oct 01, 2019 in the case of the wound rotor induction motor, it is likely to vary the figure of the torque speed curve by adding additional resistors in the rotor circuitry of the induction motor.
Early tesla westinghouse 2 phase wound rotor motor. We can control speed in two sides, stator side and rotor side. Unbalanced external resistance on wound rotor induction motor. Speed control of three phase induction motor voltage control, voltage frequency. The technique of starting wound rotor motors with resistance in the rotor circuit is also used f. By changing the resistance on the rotor through contactor, you can limit the starting torque and speed of the motor for your specific application. Slip ring induction motor fundamentals pnpntransistor. The speed control of three phase induction motor from stator side are further classified as. The 3phase set of currents, each of equal magnitude and with a phase. I have a drawing of a wound rotor induction motor for a crane. Changing rotor slip important to match the motor to the load ensure that a change in motor power gives a desired change in load speed load should have a substantial inertial components inertial torque can carry the load through brief periods when motor torque cannot best used with motors. Explain why controlling the rotor current controls the stator current also.
Wound rotor induction motors therefore have their rotor currents accessible at the stator brushes, where they can be examined and where extra resistance can be inserted into the rotor circuit. What are the methods to control speed of wound rotor. The change in speed or slip required is normally small. The value of s for a medium sized motor may vary from 1 on no load to 3% on full load. For a 4 pole, 50 hz induction motor, the variation in speed from noload to full load could be 1485 to 1455 rpm. The rotor of a squirrel cage motor is made of conductive bars that are parallel. Name three factors that determine the amount of torque developed by a wound rotor induction motor. Rotor resistance controls speed of wound rotor induction motor. The main advantage of this scheme is that the powerconditioning unit has to handle only a fraction of the total power so as to obtain full control of the generator. The wound rotor induction motor or slip ring motor is widely used for applications requiring speed control or low. Speed control of induction motor detailed explanation. Among the many motors to choose from, we used a wound rotor induction motor because of the easy access to the rotor terminals. Pdf speed control of three phase wound rotor induction. Slip ring induction motor construction, working and its speed.
This speed control technique is only useful over a range of 50% to 100% of full speed. Rotor resistance controls the speed of wound rotor induction motor. Motors employing this type of rotor are known as squirrelcage inductionmotors. Information and recommendations for the engineer fe1100. Wound rotor induction motor applications how it works wound rotor motors are an extremely versatile breed of induction motors. Methods of speed control for polyphase induction motors. Because the torque curve of the motor is effectively modified by the resistance. The wound rotor motor is particularly effective in applications where using a squirrelcage motor may result in a starting current thats. Mar 20, 2021 speed regulation is poor with respect to changing torque loads. This is a cheap, simple and efficient method for speed control of induction motors even at low torque and low speed requirements. In fact, until about 1985, a wound rotor induction motor was the only large ac motor that controlled starting characteristics and adjustable speed capability. Slip ring induction motor is used for those industrial drives which require high starting torque. An efficient, low cost, simple speed control scheme is presented for wound rotor induction motors. Slip power recovery system for variable speed operation of.
Since the rotor impedance is low, the rotor current is excessively large. Induction motors can only readily be slowed by either 1. By eliminating the need for a rotor mounted synchronizing module, ge has further improved motor reliability. Wound rotor motors deliver speed control of heavy and hightorque loads. The output control method of a speed control circuit can be divided roughly into two groups. In todays industry, wound rotor motors are increasingly rare, having been phased out by controlled drives with squirrelcage motors. Torque speed characteristic of induction motor having known the torque speed characteristic of the motor, its speed can be controlled in three ways. Pdf speed control of three phase induction motor using plc.
Slip is the difference between the synchronous speed and the actual speed the motor is spinning at. List the three types of speed control of wound rotor induction motor and illustrate the speed control by means of varying rotor resistance method. Speed control methods for wound rotor ims electric equipment. Sprs operation inu isu sprs inverter control converter control dc sprs control grrlrr a slip ring motor starts by the directonline method with grid rotor resistance grr connected to rotor. As a result, the induction motor cannot produce torque near synchronous speed. Simulation and speed control of induction motor drives 2012 3 p a g e further, s 120fp rpm 2. Speed control of wound rotor induction motor using rotor resistance. Torquespeed characteristics of a woundrotor induction motor. Speed control of 3phase induction motor microchip technology. A thyristor based ac regulator used for stator voltage control, works efficiently at this condition. The equivalent resistance in the circuit can be adjusted by an electronic control system, the slip of the generator can be affected and the rotor speed is changed. International journal for research in engineering application. Speed control of three phase induction motor electrical4u. The resistors for these manual drum controls are a little tricky to size.
Squirrelcage rotor almost 90 per cent of induction motors are squirrelcage type. Wound rotor induction motors ac motors electronics. The stationary part of the motor is called stator and rotary part of the motor is called rotor. At starting, the voltage induced in the induction motor rotor is maximum q s 1. Performance enhancement of wound rotor induction motor. What are the speed control method of induction motors. It is possible to take advantage of this feature to modify the torque speed characteristic of the motor. Speed control of dc series and shunt motors armature and field control, wardleonard control system using controlled rectifiers and dc choppers applications. This article encompasses the working principle of slip ring induction motor, construction, speed control, resistance calculation and its applications. This not only gives reliable starting but also ensures the best protection for your investment. Torquespeed control of wound rotor induction motors using. In this type of three phase induction motor the rotor is wound for the same number of poles as that of stator but it has less. At synchronous speed, no torque is produced by the motor.
Squirrel cage induction motor is used in lathes, drilling machine, fan, blower printing machines etc. Gogoi professor, department of electronics and electrical engineering, iit guwahati certificate this is to certify that the. The mechanism employed here is to control the speed via a single thyristor acting as an onoff switch at the rotor side. Because of its overall length, a complete source file list ing i. After the motor achieves the desired speed, control can be shifted to sprs by auto or manual. Speed control of wound rotor induction motors by ac. The most basic ways to control the speed of a slip ring induction motor is either from the stator or rotor side. Elements of motor action in an induction motor, the single conductor of the previous example is replaced by the rotor winding.
Constant speed drive control for a wound rotor induction. Starting and control of slipring induction motors597 the use of wound motors is on the wane, for reasons of inherent advantages of a squirrel cage motor over a wound motor and the availability of static drives which can make a squirrel cage motor perform the same duties as a wound motor and even better. Two basic design types depending on the rotor design. Wound rotor motors are also used with either manual or automatic. Torquespeed control of wound rotor induction motors using a. Featuring a rugged design, these machines provide the unique ability to gradually bring up to speed highinertia equipment and large loads smoothly and easily. Wound rotor tecowestinghouse motor company, a world leader. The induction motor is therefore a machine of substantially constant speed. Explain why the wound rotor motor produces the greatest amount of starting torque per ampere of starting current of any threephase motor. Torque speed control of wound rotor induction motors using a dc chopper circuit. A secondary use of the slip ring motor, is to provide a means of speed control. This article will explain and perform the speed control of the induction motor. This gives rise to a rotating magnetic field when current flows through the stator.
The works of the stator is common in all motor to develop a magnetic field. Manual starters are often used for smaller motors up to about. General purpose slipring induction motors product catalogue. Wound rotor or slip ring induction motor the stator of both types of motors consists of a three phase balanced distributed winding with each phase mechanically separated in space by 120 degrees from the other two phase windings. Speed control methods of various types of speed control. After the addition of resistor in rotor circuitry, the new torque speed characteristic curve is shown in the given diagram. This speed control technique is only usefull over a range of 50% to 100% of full speed. Two pole, 50 hz three phase induction motor supplies 15 kw to a load at its rated speed what is synchronous speed of the induction motor if. Speed control methods for wound rotor ims electric. Constant speed drive control for a wound rotor induction motor. List the three types of speed control of wound rotor. Speed control of wound rotor induction motor pdf the writers of speed control of wound rotor induction motor have made all reasonable attempts to offer.
An induction motor or asynchronous motor is an ac electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic. Jul 09, 2019 wound rotors have winding schemes similar to stators typically wound for 3 phases and with a pole count matching the stator. Oct 26, 2020 the speed of induction motor is changed from both stator and rotor side. Speed control of induction motor using vf technique phase i a thesis submitted in partial fulfillment of the requirements for the degree of bachelor of technology submitted by jeetesh kumar 08010815 kamakhya prasad basumatary 08010817 supervisor professor a. Almost 90% of induction motors are squirrel cage motors. Squirrelcage rotor almost 90 per cent of induction motors are squirrelcage type, because this type of rotor has the.
Power converter has been connected to the rotor of wound rotor induction generator to obtain the optimum power from variable speed wind turbine. Wound rotor induction motors ac motors electronics textbook. In the stator side, there are three methods to control the speed. Speed control methods of the various speed control motors. Speed control of wound rotor induction motor pdf scowrim158 download full version pdf for speed control of wound rotor induction motor using the link below. A price is paid for the extra possibilities offered by wound rotor motors, as they are more expensive and less reliable than their squirrelcage counterparts. Changing rotor slip important to match the motor to the load ensure that a change in motor power gives a desired change in load speed load should have a substantial inertial components inertial torque can carry the load through brief periods when motor torque cannot best used with motors designed for high slip. Slip rings are used to connect a wound rotor to external resistance to change the motor speed torque characteristic. This type of 3phase induction motor has high starting torque, which makes it ideal for applications where standard nema design motors fall short. Closedloop control system for torque and speed control of the wound rotor motor. Speed control 221 polechanging motors 222 voltage control of highresistance cage motors 223 speed control of wound rotor motors 224 power factor control and energy optimisation 225 voltage control 225 slip energy recovery wound rotor motors 227 singlephase induction motors 227 principle of operation 227 capacitorrun motors 229 splitphase. Speed control of wound rotor induction motor pdfscowrim158.
The basic idea of an electric motor is to generate two magnetic fields. Torque speed characteristics of motors 17 4 ac motors 19 a. Pdf speed control of three phase induction motor using. Motors employing this type of rotor are variously known asphase wound motors or wound motors or as slipring motors. What are the methods to control speed of wound rotor motors. An induction motors rotor could be of two types, squirrelcage rotor slip ring or phase wound rotor there are generally two kinds of induction motor which rely upon the particular input supply, which are single phase induction motor three phase induction motor threephase induction motors are more commonly employed in adjustable speed drives. The rotor of a squirrel cage motor is made of conductive bars that are. Starting of 3phase induction motors the induction motor is fundamentally a transformer in which the stator is the primary and the rotor is shortcircuited secondary. The same circuit can be used as a starter speed control and loss minimization. In this scheme, the rotor windings are connected through slip rings and brushes with an external variable resistor. Speed regulation is better than that of the series field motor. Pdf speed control of three phase wound rotor induction motors. Wound rotor induction motors wrim have been popular for decades in the cement and mining industry for starting and driving large grinding mills. Then the rotor resistance is controlled for the adjustable speed.
C motor starters typical control circuits for shunt and series motors three phase squirrel cage and slip ring induction motors. What are the speed control method of induction motors the. The rotor will constantly be turning to align its magnetic field with that of the stator field. Performance enhancement of wound rotor induction motor by. The two main types of ac motors are induction motors and synchronous motors. File type pdf induction and synchronous machines 7.
Wound rotor tecowestinghouse motor company, a world. Chopper speed control of the wound rotor induction motor in addition to speed control, torque adjustment at locked rotor and current limiting during starting and acceleration, this circuit provides better speed regulation, smoothness and the ability to be used in closedloop control system for torque and speed. Speed control of wound rotor induction motors by ac regulator. Speed control of dc series and shunt motors armature and field control, wardleonard control. Wound rotor induction motor the engineering projects. An induction motor is practically a constant speed motor, that means, for the entire loading range, change in speed of the motor is quite small. Speed of a dc shunt motor can be varied very easily with good efficiency, but in case of induction motors, speed reduction is accompanied by a corresponding loss of efficiency and poor power factor. Pdf speed control of induction motors kamakhya basumatary. Figure 1 below shows the graph of torque versus slip. Motors employing this type of rotor are variously known as phase wound motors or wound motors or as slipring motors. In rotor resistance control, if equal resistances are included in each secondary phase of three phase induction motor, the speed, starting.
Several methods have been proposed for performance improvement of wound rotor induction motor by rotor control. Induction motor as an extension to the available non slip power recovery mechanisms available for low power srims. A wound rotor induction motor also known as a would round motor or slip ring induction motor is defined as a special type of 3 phase ac induction motor designed to provide high starting torque by connecting an external resistance to the rotor circuit. The construction of the slip ring induction motor is exactly similar to the construction of squirrel. Speed control works well with variable speed loads like elevators and printing presses. The speed regulation is poor with respect to changing torque loads. Both stator voltage control and rotor resistance control methods. Polyphase induction motors are mainly of two types by construction, squirrel cage and wound rotor with sliprings.
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