Thus, a salient pole rotor consists of poles projecting out from the surface of the rotor core. Animation showing operation of a brushed dc electric motor. The shaft and pole bodies are of integral construction, produced from a single normalized carbon steel forging. Now imagine trying to wind perhaps 20 poles on a round rotor. With our engineering capabilities and dedicated manufacturing production line, we can easily address your field pole refurbishment needs, and should your project scope require it, nec can manufacture completely new pole pieces. Vector diagram correlation of leading and lagging power factor in salient pole synchronous machine onuegbu j. The switched reluctance motor srm is a type of stepper motor, an electric motor that runs by. To facilitate calculation, consider using normalized pu parameters. Determine the suitable values for diameter and length of 75mva 75000kva, 11kv, 50hz 3000r. Steadystate charateristics of a salientpole synchronous machine. Salient pole generators will have typical speed about 100 to 375 rpm. The simple singlephase machine in figure 1 is capable of producing torque over only half of its electrical cycle. In the nonsalient pole pole machine,xd is nearly equal to xq.
The wound rotor salient pole synchronous machine wrsm is generally used in very high power applications associated with a cycloconverter low speed applications or a current source inverter. Animated phasor diagrams of a synchronous generator compounding curve 27. This rotor has solid poles and a striponedge field winding. Nevertheless, this machine allows high efficiency and high. Difference between salient pole and non salient pole smooth. Nec services for salient pole rotors national electric coil. In power system analysis software, the synchronous machine equations are commonly solved using the directquadraturezero transformation technique. Around the periphery of each pole core are the copper windings. In salient pole type of rotor consist of large number of projected poles salient poles mounted on a magnetic wheel.
They allow better ventilation the pole faces are so shaped that the radial air gap length increases from the pole center to the pole tips so that the flux distribution in the airgap is sinusoidal in shape which will help the machine to generate sinusoidal emf. Determination of load angle for salientpole synchronous. The switched reluctance motor srm is a type of stepper motor, an electric motor that runs by reluctance torque. Rotor position and velocity estimation for a salientpole. What are the advantages of a round rotor generator than a. Advantages of cylindrical rotor over salient pole rotor. Pdf study of salient poles synchronous generator by finite. The rotor winding is provided on these poles and it is supported by pole shoes. As the speed of the water turbine is slow hence more number of poles are required to attain the frequency. Operating characteristics of a roundrotor synchronous machine. Characteristics and work principles of switched reluctance. In the cylindrical rotor synchronous machine, the air gap is uniform.
A field coil is an electromagnet used to generate a magnetic field in an electromagnetic machine, typically a rotating electrical machine such as a motor or generator. Model the dynamics of threephase round rotor or salient pole synchronous machine. In general, the cylindrical rotor type machines are confined to 2 and 4 pole turbine generators, while salient pole types are built with 4 poles upwards and include. Elementary 3phase salientpole alternator and generated voltages. Shaikh 6 types of rotor the two types of rotor are. The salient pole type of rotor is generally used for slow speed machines. The cu loss in rotor is not met by motor ac input, but by the dc source used for rotor excitation. The projected pole are made up from laminations of steel.
Which is stiffer between salient pole rotor and cylindrical. Difference between cylindrical and salient pole rotor. Since the location of e0 is unknown id and iq cannot be found which are needed to draw the phasor diagram. Salient pole rotor how is salient pole rotor abbreviated. For the unsaturated analysis, it is assumed that the permeability of the iron core is so high that its reluctance is. Elementary 3phase round rotor synchronous generator. Two reaction theory salient pole synchronous machine. Why are salient pole rotors preferred in hydro plants. Construction of a synchronous machine circuit globe.
Salient pole synchronous machine two rection theory. The rotor is a large magnet with poles constructed of steel lamination projecting out of the rotors core. This paper presents a representation of the stator to rotor self and mutual inductance and derivative distributions in the 5. The poles are supplied by direct current or magnetized by permanent magnets. Our rotating equipment service center is set up to rewind salient rotor poles and to repair, refurbish, and requalify salient pole rotors. The effects of design factors on the torque and the mechanical characteristics are investigated. The pole structure of the rotor of a salient pole machine makes the air gap highly nonuniform. This paper is focused design calculation of 30 mva, 11 kv, 50 hz, two pole non salient poles synchronous generator that use in gas turbine power plant. Wound field 5pole doubly salient synchronous generator realizations. The armature with a threephase winding is on the stator where voltage is induced.
The projected poles are made up from laminations of steel. Well assume youre ok with this, but you can optout if you wish. Non salient pole or cylindrical rotors are cylindrical in shape having parallel slots on it to place rotor windings. This paper presents a calculation method for leakage. The poles, in turn, are composed of a laminated steel core, surrounded by an insulated copper coil. Vector diagram correlation of leading and lagging power. It is a solid salientpole rotor having projecting magnetic poles made of soft magnetic material often laminated steel. Difference between salient pole and non salient pole. The end view of a typical 6 pole salient pole rotor is shown below in the figure. This website uses cookies to improve your experience. Mechanical characteristics obtained based on the fem and analytical dependences are compared. Exciting rotor winding salient poles fed via 2 slip rings with dc current. Construction of salient pole rotor is shown in the figure left. Explained the difference between salient pole and non salient pole rotor compare salient pole and cylindrical rotor difference between salient pole and cylindrical pole machine difference.
It means they do not project out from the surface of the rotor. Salient pole generators will have large diameter and short axial length. In the salientpole machine the poles magnetic field is produced by a winding. Elementary 3phase salient pole alternator and generated voltages. Over certain regions, the slots are omitted to form the surface of the rotor.
Advantages to some extend only seem to show due to comparing apples and pears. It also enables a soft start function in software form, in order to reduce the amount of hardware required. Feasibility of redesigning an existing product to include the. Two reaction theory of salient pole synchronous alternator. Why is the salient pole rotor in a synchronous machine made of laminated steel whereas a cylindrical rotor does not have any lamination. Commercial generators almost always use 3600 rpm or 3000 rpm with a two pole rotor. Salient pole synchronous generators are mostly used in hydro power plants.
Construction of a salient pole rotor is as shown in the figure at left. An ebook reader can be a software application for use on a computer. Therefore salient pole machines will have typically number of poles will be between 4 to 60. Explained the difference between salient pole and non salient pole rotor compare salient pole and cylindrical rotor difference between.
What is the difference between a salient pole and a. Cylindrical rotor round rotor it is constructed from a solid steel forging so as to withstand the large centrifugal stresses inherent in high speed operation. In salient pole type of rotor consist of large number of projected poles i. Salient pole rotors generally need damper windings to prevent rotor oscillations during operation. Model the dynamics of threephase roundrotor or salientpole synchronous machine. The salient pole constructionwith gaps between poles rather than a solid circular crosssectioncreates a relatively lowinertia rotor which allows for rapid dynamic response and minimizes risk of mechanical damage from shock loads in highratio, geardriven applications, boteler explains. Each pole is fastened to the rotor spider by a dovetail and opposed wedge system. Unlike common dc motor types, power is delivered to windings in the stator case rather than the rotor. Look at a round rotor and see how the turns are laid into the surface of the rotor. Using a mallet, hold the rotor in one hand and use the other hand to tap the salient pole firmly with the mallet in order to remove the rotor from the motor shaft. Cylindrical rotor type synchronous generator salient pole rotor type. Analytical expressions for the electromagnetic torque of a salientpole brake with a hollow nonmagnetic rotor are obtained. Electrical machines short answers instrumentation tools. By stiffness of synchronous machines,we mean that the amount of synchronising powerpsavaliable, for machines at a particular operating point, to bring back the machine to synchronism when the machine is subjected to disturbances.
More demanding applications use higher pole numbers on the rotor and stator, with the stator poles wound and connected into multiple identical phases. The two main types of synchronous machine are cylindrical rotor and salient pole. Modeling of salientpole brake with hollow nonmagnetic rotor. Field pole windings nec has expertise with both new and refurbished windings for salient pole rewinds. The rotor of the srm are made of laminated steel, a soft magnetic material which gives the rotor projecting magnetic poles, hence described as salientpole rotor. In the circuital linear and nonlinear model, the stator to. This paper describes the influence of the graded air gap on the performance of a salient pole synchronous generator in terms of total harmonic distortion and air gap flux density waveform. Design of salient pole synchronous machine matlab examples. Solid salient pole motor synchronousmotor ge power. A synchronous motor is only considered doubly fed if it is supplied with independently excited multiphase ac electromagnets on both the rotor and stator. Compatibility design of non salient pole synchronous. Difference between salient pole and non salient pole smooth cylindrical rotor duration. Synchronous generator salient pole vs non salient pole.
Model of pm synchronous machine in the rotor reference frame. For those reasons, a linear model of the machine will be explored in this section. The rotor in turn, is a steel fabrication, which supports the rim and the pole. There are two types of rotor construction, namely the salient pole type and the cylindrical rotor type. Pdf study of salient poles synchronous generator by. Turbo alternator construction diy electrical electronics. Also determine value of flux conductor per slot, number of turns per phase, size of armature conductor. The main difference between the cylindrical rotor and salient pole classes of. Model the dynamics of threephase roundrotor or salient.
Machine powered by electricity that converts electrical energy into mechanical energy rotation. In a rotating machine, the field coils are wound on an iron magnetic core which guides the magnetic field lines. Salient pole rotor optimisations for synchronous generators using fea software abstract. Consider a 2 pole, salient pole rotor rotating in the anticlockwise direction within a 2 pole stator as shown in the figure below. In salient pole type of rotor consist of large number of projected poles salient poles mounted on a magentic wheel. The first method uses optical encoder to detect the rotor position. Each pole is a dc magnet, whose magnetic flux induces a current in the stator windings. Transient stability of a synchronous machine described by voltage space vectors.
What is the difference between a salient pole and a cylindrical pole. Figure 3 illustrates the cross section of a threephase 64 machine. At this moment it is good to refresh the pros of nonsalient type rotor over salient type rotor. Salient pole synchronous motor power developed by a salient pole synchronous motor effects of excitation on armature current and power. Switched reluctance motor the switched reluctance motor. Force is produced when the stator winding receives power, and the rotor creates a magnetic reluctance which forces the rotor pole to align to a stator pole nearest to it. Study of salient poles synchronous generator by finite elements analysis.
The poles are installed on the rotor so that their magnetic polarity alternates from north to south for every pole. In some cases the end of the rotor shaft is not free to be used and mounting of an encoder is impossible. Why salient pole synchronous machine are more stable than. Designed, built and tested in the motor factory, solid salient pole rotors are suitable for applications requiring long duty cycles. This greatly simplifies mechanical design as power does not have to be delivered to a moving part, but it complicates the electrical design as some sort of switching system needs. The rotor winding is provided on these poles and it. Jansen and lorenz 15, 17 proposed an estimation technique for the induction machine that utilizes an injected. With our engineering capabilities and dedicated manufacturing production line, we can easily address your field pole refurbishment needs, or should your project scope require it, the manufacture of. An electric motor is an electrical machine that converts electrical energy into mechanical. Salient pole rotor synchronous machines are stiffer as explained below.
Modelling of a wound rotor salient pole synchronous. This paper presents two methods for load angle determination for salientpole synchronous generator. There are mainly two types of rotors used in construction of alternator. There are mainly two types of synchronous generator from rotor construction point of view. The construction of so many poles on a round rotor would be very difficult to get enough turns on each pole. Automatic voltage regulator avr or manually excited. Noxon rapids rotor units 1 thru 4 325 ton units 14 300 ton unit 5 72 salient poles units 14 68 salient poles unit 5 fastened to the generator shaft by 48 3studs.
Double excited magnetic systems instrumentation tools. The first electromechanical rotating machines had salient poles and did not make good motors it was not long after it was shown that an electrical current produced a magnetic field that could move magnets and seemed to circle around a wire carrying current that experimenters searched for evidence of movement produced by electricity. Salient pole and non salient pole synchronous machine. Rotor position and velocity estimation for a salientpole pmsm 785 fig. It consists of a coil of wire through which a current flows.
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