DC motor drive best chopper converter Discussion : 1. Why is the electronic switching being suitable for this type of drives ? 2. Why is freewheeling diode used in this type circuits ? 3. The change in the current for each ON and OFF duty is not happened suddenly ? 4. Changing the switching frequency or the duty cycle will affect the load current, explain that .

DC motor drive best chopper converter Discussion : 1. Why is the electronic switching being suitable for this type of drives ? 2. Why is freewheeling diode used in this type circuits ? 3. The change in the current for each ON and OFF duty is not happened suddenly ? 4. Changing the switching frequency or the duty cycle will affect the load current, explain that .

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter56: Magnetic Clutch And Magnetic Drive

Section: Chapter Questions

Problem 3SQ

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a) Which components determine the excitation current of a transformer? How are they in transformer equivalent circuit modeled? b) Why is the polarity determination of a transformer made? Briefly explain how the experiment is done. c) If the direction of rotation of the motor changes when the feeding ends are changed in a DC motor, what can be said about its type? d) Why does the peak voltage increase as the serial DC generator is loaded? How long does this increase continue?
(TRUE OR FALSE) - Shunt motor should not be started on no-load. - Field copper loss is likely to have highest proportion at rated load ofthe DC generator. - In a DC generator, the iron losses mainly take place in the commutator. - Energy conversion of DC generator is based on the principle ofproduction of dynamically terminal voltage. - Increasing the speed of DC motor, the back emf will decrease but theline current falls. - The current drawn by the armature of DC motor is directly proportionalto torque. - Lenz’s law rule is used to determine the direction of rotation of dcmachines. - Compound dc motor at no-load it regulates highest speed. - The direction of this force is perpendicular to both the wire and themagnetic field in DC motor. - The direction of DC motor induced emf is such that the same of thearmature current.
A series dc motor 20-hp, 500-V, is having armature, series field and shunt field winding resistances of 0.08 Ω, 0.3 Ω and 125 Ω, respectively. If the back – emf is 478 V, determine the motor current when the connection is a) long – shunt. b) short – shunt c) series d) shunt
3. A dc shunt motor operating unloaded at a terminal voltage of 125V at a speed of 1420 rpm. When themotor is operated unloaded at the same terminal voltage but with an additional resistance of 8Ω in serieswith the shunt field, the motor speed is 1560rpm. (Ignore armature reaction and magnetic saturation)a) Calculate the resistance of the shunt field.b) Calculate the motor speed if the series resistance is increased from 8Ω to20Ω. c) With the field resistance at its original value and no series resistance, calculate the motor speed if it isoperated loaded at a terminal voltage of 90 V and a terminal current of 100A.
Draw and explain the operation of H-type with 4-switches per phase drivecircuit and the drive circuit for bifilar winding for stepper motor. In whichtypes of stepper motors these circuits are used?
Manual Control: Design a dc motor circuit to drive an assembly line consisting of a conveyor belt moving horizontally. The load on the belt varies depending on the number of goods being moved. The load torque seen by the motor varies from a maximum of 20 Nm to a minimum of 5 Nm. At all loading conditions, the speed of the motor must be maintained constant and equal to 150 rpm. a. To achieve the required operation, the armature voltage of the motor is adjusted by a single-phase, full-wave, ac/dc converter. The input voltage and frequency to the converter are 240 V (rms) and 50 Hz. (Hint: Motor type, Motor rating, α range, Supply voltage, and frequency...etc) Automatic Control: Modify the design to automatically adjust the voltage to maintain the speed equal to 200 rpm within the specified torque range. (Hint: control variable, controller type, connection, controller weights..etc)
The armature, series field and shunt field resistances of a 125kW, 250V long shunt cumulative compound dc generator are 0.025-ohm, 0.01 ohm and 30 ohms, respectively. If the stray power loss at rated load is 5kW, determine the motor brake horsepower required to drive this machine. Assume a brush drop of 2V and a stray load loss of 1% of the output.
Briefly explain block diagram of electric drives.
A 4 pole10V, DC shunt motor operates on a load current 10A, having wave connected armature with 200 conductors. The flux per Pole is 25 m Wb. Resistance of shunt field winding is 1 ohm and resistance of the armature is 0.15 ohm. d) Based on the back emf voltage value Eb= 10V, is it possible to be achievable this value? Give reason.
. Define stepper motora. Explain the internal structure of stepper motorb. With Table explain the clockwise and anticlockwise rotation of stepper motorc. With neat interface diagram and program explain how to interface stepper motor to 8086microprocessor.
A shunt generator has a field resistance of 60 ohms. When the generator driven 6KW, the terminal vtage is 125 Volts, while the generated emf is 133V. Determine a.) The armature resistance, and b.) The generated emf when the output is 2KW at terminal voltage of 135 V.
13. A synchronous machine is run as an unloaded motor. If a low voltage is supplied at the ratedfrequency, and if the full-load armature current flows, a test is being run to determine theA. windage loss.B. I²R loss.C. stray-load loss.D. core loss. Note: I have doubts if it is the letter A or the letter B, can you help me in this question, thanks.