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Instructions:
Consider a 3-phase induction motor (wound) with the following specifications:
- Nominal Power: 420 kVA
- Voltage (RMS) (line voltage): 690 V
- Frequency: 50 Hz
Question 1:
In Simulink, draw the diagram and display the following outputs for the No-Load test. (A block diagram in Simulink is required).
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a) |
Display 3 phase input phase voltage waveforms (using scope) |
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b) |
Display RMS value of the input current (using display block) |
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c) |
Display Active and Reactive power (using display block) |
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d) |
Display RMS voltage of just one phase (using display block) |
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e) Display power factor (using display block) ()
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Display rotor speed in rpm (using display block) |
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g) |
Show the rotor speed graph in rpm |
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h) |
Calculate the power factor based on your finding. |
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Hint:
Note:
- As a power supply, choose a three-phase programmable voltage source.
- As induction motor, choose Asynchronous Machine SI Units.
- Make sure powergui is set to Discrete.
- To measure active and reactive power, choose Active and reactive power measurement (3ph).
- Set Stop Time to 0.3.
Power supply set up:
- Change amplitude, phase and frequency to 690, 0, and 50 respectively.
Induction motor set up:
- Rotor type: Wound
- Mechanical input: Torque TM
- Reference frame: Rotor
- In section Parameters: make sure the nominal power is 420e+04 VA, voltage is 690 V and frequency is 50 Hz) and set the value of Slip as 0.001)
- Connect a constant block with the value of "0" to the Tm input of the IM as a Mechanical Load.
- Connect all three output phase (a,b,c) together.
- Connect output m to a Bus selector and select Rotor Speed (wm) to display the rotor speed. (Note that the rotor speed is in rad/s and you need to multiply that value by 9.5492 to show find it in rpm).
Power factor calculation:
- To calculate the power factor you can use either power factor measurement block or if it's not included in the library, you need to create it based on the formula: P = 3VphI cos ?,
therefore cos ? = Pactive.
3VphI
- In this case, you need a product block, a constant block (equals 3), an RMS value of one phase voltage, an RMS value of one phase current and a Divide block as follows:
RMS Voltage phase A
RMS Current phase A
Real Power
Display .png)
Question 2:
For the induction motor in Question 1, set up the blocked-rotor test (short circuit test). (The Simulink block diagram is required).
a) Display rotor speed (using display block).
b) Display real and reactive power (using display block).
d) Display blocked-rotor resistance( )
e)Take a screenshot Block-Parameters of the induction motor to confirm that the values of and that you found are approximately equal to Stator resistance + Rotor resistance
and Stator inductance + Rotor inductance.
Hint:
.png)
Note:
• Consider the value of Tm=25 as Mechanical Load.
• Change the slip to "1".
• Change the inertia to "inf".
• Decrease the value of the input voltage to 60 V.
• To calculate the value of Rbr and Lbr, you need to create the following formulas in your
Simulink:
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• Rbr = |
Pactive |
, Xbr = |
Qreactive |
, furthermore Xbr = Lbr? ? Lbr = |
Qreactive |
, so you need to |
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3I |
2 |
3I |
2 |
3?2??f?I |
2 |
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ph |
ph |
ph |
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create the following block diagrams to read the values:
.png)
Question 3:
The induction motor in question 1 has 2 pairs of poles. In the induction motor parameter, change the pair pole to 6, increase the stop time to 0.7s and run your simulation.
a) Show the rotor speed output (using scope and display)
b) Justify your observation using the appropriate formula.
Question 4:
We need a synchronous motor. Motor A will be used in a high-power low-speed application and Motor B will be used in a low-power high-speed application. What type of motor should be chosen for each application? Salient pole or cylindrical? Discuss your recommendation.