The special technique is pole amplitude modulation pam of the induction motor stator winding which can be accomplished with either. If possible, graph this on a graphing calculator or other computer plotting device. The basic feature of pole amplitude modulation pam winding is the layout, which is irregular. An original method of changing the speed of squirrelcage induction motors has recently been developed which enables efficient and economic operation to be obtained at either of two chosen speeds, using a single winding of standard type. This type of modulation is known as double sideband suppressedcarrier dsbsc. This form of modulation is used for vhf aircraft communications and was described earlier in chapter 4. What does ppm pulse position modulation mean in drone. This invention relates to poleamplitude modulation p. Farshad lahouti january 20, 2003 winter 2003 uw, ece 318 lecture notes 2 information source signal modulator propagation channel signal demodulator information destination analog communication system analog signals may be transmitted directly via carrier modulat ion over. Identifying the vibration problems that can occur in inductionmotor drives have an added complexity due to the rotating magneticfields in the machine. Pdf in electric drive applications that are based on highspeed induction machines. The standard equation of the angle modulated wave is in amplitude modulation, the.
Science only amplitude phase and frequency of the wave can be changed so we have three basic type of modulation 1. The motors designed for speed changing based on the poled amplitude modulation scheme. The concluding part will be spent looking at the more popular form of high level modulation known as collector modulation or heising, named after its inventor. Basic concept of modulation the information source typically a low frequency signal referred to as the baseband signal carrier a higher frequency sinusoid example. Dynamic power supply design for highefficiency wireless transmitters by jason t. Demonstration with professor sandy hill from the university of massachusetts at amherst. Pole amplitude modulation is a flexible method of pole changing which can be used in applications where speed ratios other than 2. Simply put, in analog pulse modulation a periodic pulse train is issued as a carrier and some of the parameters of pulse is modifi. In amplitude modulation, the amplitude signal strength of the carrier wave is varied in proportion to that of the message signal being transmitted.
Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal. An original method of changing the speed of squirrelcage induction motors has recently been developed which enables efficient and economic operation to be. Winding design, modeling, and control for pole phase modulation induction motors article pdf available in ieee transactions on magnetics 492. Rc audio generator, oscilloscope, and spectrum analyzer demonstrations with speech and radio. Pole changing epc technique for multiphase induction motor im is. In fact, tecowestinghouse has more pole amplitude modulation pam motor experience than all of our competitors combined. A 3phase induction motor is theoretically self starting.
Initially, the birth of amplitude modulation starts by considering a continuous spark transmission and placing a carbon microphone in the antenna lead. Poleamplitude modulation polechanging electric motors and. Let us considered that the mmf distribution in the air gap of a three phase induction motor due to the stator winding carrying a three phase balanced currents can be written as shown below. Graphical computation of amplitude response from poles and. The other type of modulation in continuouswave modulation is angle modulation. Poleamplitude modulation polechanging electric motors. It is usually easy to sketch a qualitatively accurate amplitude response directly from the poles. More amplitude modulation increases the peak to average power ratio par, which is a measure of the peak to average power supplied to the antenna by. Inductionmotor speedchanging by poleamplitude modulation iet. A 4 pole motor runs at a speed less than 1800 rpm or 30 hz and so on. There are no amplitude scales shown, but you should be able to deduce the depth. Amplitude modulation am 9 t15 use speech or music from trunks as the message, and show that this also generates a trapezoid, and that setting the message amplitude so that the depth of modulation reaches unity on peaks a triangle is especially easy. Amplitude modulation in wind turbine noise valeri v. A pole changing induction motor with pole amplitude modulation l, 21 makes it possible to realize the speed ratio not equal.
Before looking at that, it is a good exercise to try sketching it by inspection of the pole zero diagram. It is shown that the period of the chandler wobble of the poles cwp is a combined oscillation caused by three periodic processes experienced by. Tecowestinghouse is the world leader in pam motors, offering more experience. Speeds are changed electronically, not mechanically, which means additional apparatus between the.
As illustrated in figure 5, the amplifier is biased class c and the output rf signal amplitude is modulated by causing the collector supply voltage to vary with the modulation voltage. Even there was a disturbing noise, signals can be heard over. A pole changing induction motor with pole amplitude. Method of consequent poles pole amplitude modulation pwm 3rd class ac machines dr. Analog communication angle modulation tutorialspoint.
This type of positioning has created sound waves, and these got varied both with the intensity and resistance over the transmission. The pole amplitude modulation technique is explained in this article with the help of an example. It is shown that the period of the chandler wobble of the poles. Mcnames portland state university ece 223 communications. Inaam ibrahim 45 the methods of speed control by pole changing are suitable for cage motors only because the cage rotor. The method has considerable generality, but is particularly applicable to speed ratios not very different from unity.
Dynamic power supply design for highefficiency wireless transmitters jason t. Speed control three phase im using pole amplitude modulation the value of m 1 means reverse connecting pole groups 5, 6, 7 and 8 resulting in signreversed dotted poles. Application notes vibration diagnostics for industrial electric motor drives the induction motor is the most widely employed industrial electricdrive. Amplitude modulation am is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In small machines the effect, although present, is less important.
Predtechensky pereulok, 11, moscow 123242, russia email. A 2 pole a c induction motor being powered by a 60 hz line frequency runs at a speed slightly lower than 3600 rpm or 60 cycles per second hz. Tecowestinghouse pam motor an economical drive for multispeed applications through pole amplitude modulation. This technique applies the logic of amplitude modulation to the spacedistribution of the windings of an electrical machine. Dynamic power supply design for highefficiency wireless. Design of phasechange twospeed windings for induction. Sampling theorem determines the necessary conditions which allow us to change an analog signal to a discrete one. Sampling theorem and pulse amplitude modulation pam. Poleamplitude modulation, polechanging electric motors. In this method of speed control of three phase induction motor, we provide two separate windings in the stator. The use of this technique enables achievement of multi different.
Speed control three phase im using pole amplitude modulation the value of m 1 means reverse connecting pole groups 5. Design of phasechange twospeed windings for induction motors, using pole amplitude modulation techniques. A poleamplitude modulation, pole number changing electric machine having a threephase stator winding comprising three phasewinding sections in delta connection and three other phasewinding sections in star connection, coils of the deltaconnected phasewindings and coils of the starconnected phasewindings following each other regularly. Overview of communication topics sinusoidal amplitude modulation amplitude demodulation synchronous and asynchronous double and singlesideband am modulation pulse amplitude modulation pulse code modulation frequencydivision multiplexing timedivision multiplexing narrowband frequency modulation j. Pole amplitude modulation pdf inductionmotor speedchanging by poleamplitude modulation. Sampling theorem and pulse amplitude modulation pam reference stremler, communication systems, chapter 3. Amplitude modulation a continuouswave goes on continuously without any intervals and it is the baseband message signal, which contains the information. Design of phasechange 2speed windings for induction motors, using pole amplitude modulation techniques. Pole amplitude modulation method pam multiple stator winding method. Speed control of three phase induction motor electrical4u. In large machine of high pole numbers, the effect of adjacent harmonics of m. Implementation of space vectorpwm for driving two level voltage source inverters mahmoud gaballah, mohammed elbardini, soliman sharaf and mohammed mabrouk. Inductionmotor speedchanging by poleamplitude modulation. Application notes vibration diagnostics for industrial.
The message signal is, for example, a function of the sound to be reproduced by a. K nown in the industry as the pam motor, the tecowestinghouse pole amplitude modulation motor is the worlds most innovative ac induction motor. Lenchine science and sustainability division, epa, gpo box 2607 adelaide sa 5001, australia abstract wind farms are gaining more and more popularity as a source of renewable energy. Pam motors offer the flexibility and energy savings of two speeds while requiring only one winding. Pole number changing is effected by reversing the starconnected winding component relatively to the deltaconnected component. A circuit often used to amplitude modulate a carrier signal is a multiplier. Pole changing between large number of pole pairs at low speed and. In pole amplitude modulation method for controlling number of poles, practically, the wave used for modulation is a. A2a ppm or pulse position modulation is one of the analog pulse modulation techniques used in digital communication. For decades, westinghouse pam motors have helped industries and utilities around the world improve operating economies. Rotor unbalancemisalignment the number of poles determines the speed of an ac induction motor. The winding configuration is deliberately determined to get a pole changing. Other is the pole amplitude modulation pam technique through which the windings are held in two sections per phase and reversing the current direction in one section of each phase with respect to the other.
These two stator windings are electrically isolated from each other and are wound for two different numbers of poles. In amplitude modulation, the message signal mt is impressed on the amplitude of the carrier signal ct a c cos2 f c t there are several different ways of amplitude modulating the carrier signal by mt each results in different spectral characteristics for the transmitted signal we will describe these methods, which are. The motors designed for speed changing based on the poled amplitude modulation scheme are known as pam motors. Pdf winding design, modeling, and control for polephase. The pole amplitude modulation pam technique is extended version of dahlander winding. Angle modulation is the process in which the frequency or the phase of the carrier signal varies according to the message signal. The pole amplitude modulation pam motor reduced wear and erosion on the driven equipment and less noise during operation at low speed. Known in the industry as the pam motor, the pole amplitude modulation motor is an innovative ac induction motor. Analysis of harmonic torques of poleachanging induction motors. Speed control in three phase induction motor mcqs with.
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