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# DFIM - Exercises

# Page Content

After completing the following series of exercises, the student will understand the design of controllers for a doubly fed induction machine.

Real-time simulation results are shown in the laboratory panel.

# Subsynchronous mode

- Load the model with the
**default settings**. - Apply an
**input torque of 0.2 p.u.**, then a reference speed of 240 rpm.- Does the measured torque follow the input torque?
- Does the measured speed follow the reference speed?
**Hint**: Look at waveforms under DFIM Control and Triggering Scopes to answer the questions above.

- Increase the
**input torque to 0.4 p.u.**- How does the increase in input torque impact the rotor and stator currents?

Explain your observation. - Does the measured torque follow the input torque?

- How does the increase in input torque impact the rotor and stator currents?

# Synchronous mode

- Set the
**input torque to zero**. - Set the reference speed to its
**nominal value of 277 rpm**.- Does the measured speed follow the reference speed?

Show your result.

- Does the measured speed follow the reference speed?
- Increase the
**input torque to 0.2 p.u.**- Observe the waveforms of rotor currents and explain their non-sinusoidal shapes.
- Does the measured torque follow the input torque?

Show your result.

# Hypersynchronous mode

- Set the
**input torque to zero**.- What do you expect as values for rotor currents?

Explain.

- What do you expect as values for rotor currents?
- Set the
**reference speed to 280 rpm**.- Does the measured torque follow the input torque?
- Does the measured speed follow the reference speed?

- Increase the
**input torque to 0.5 p.u.,**then the**reference speed to 304 rpm**.- Show that the torque and speed controllers are working properly.
- Show the current controllers for
*I*and_{d}*I*are working properly._{q}**Hint**: Showing the waveforms is enough as a solution.

- Increase the
**reference current**.*I*to 0.2 p.u_{d}- Does the measured current
*I*follow the reference?_{d}

Show your result. **Waveforms 1**: Save the waveforms of rotor and stator currents, via a screenshot, for example.

- Does the measured current
- Increase the
**reference current**.*I*to 0.4 p.u_{d}**Waveforms 2**: Save the waveforms of rotor and stator currents.- How does the increase in current
*I*impact the rotor and stator currents._{d}**Hint**: Analyze the results of Waveforms 1 and 2.

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