DFIG Motor Drive Exercise 1 IGBT Control

This exercise presents the case of a DC to AC inverter, as shown.

In this model, the simulator provides the inverter pulses where the modulation frequency, the carrier frequency, and the modulation amplitude can be controlled.

The central feature in this exercise is to compare the same circuit side-by-side based on three setups, using:

• Lab-Volt components
• Simulink model with the IGBT from Simscape Electrical™ Specialized Power Systems (SPS) formerly known as SimPowerSystems™.
• Simulink model with the IGBT from RTe-Drive.

This is done using a variable DC source where its value is directly fed into the three models. The same applies to the pulses generated by the Simulink model and fed to the physical model through the OP8660.

Materials Needed

• Variable DC source (8821)
• IGBT chopper/inverter (8857)
• Inductance
• Resistance
• Measurement (OP8660)

Test Procedure

1. Make sure the connections are identical to the circuit shown in Schematics for Exercise 1
2. Make the connections between the physical circuit and the OP8660. Pay attention to the sign of the current measurement and voltage measurement
3. In the TestDrive user interface, open the panel Ex1_IGBT
4. Click to enable the inverter, and turn on the power supply
5. On the Power Supply, slowly turn the rheostat to increase the voltage to approximately 40 volts
6. Vary the DC bus (DC power supply) voltage and observe the current and voltage changes on the scope at the right

7. Now vary the modulation frequency

Before making any high voltage connections, the firing pulses must be tested for various cases.

• The cable between the Lab-Volt IGBT chopper/inverter switching control and the OP8660 must be connected.
• You can test both Inverter1 and Inverter2 by using two IGBT chopper/inverter modules

• The All_resistive model must be ready to load
• Connect an oscilloscope to the IGBT chopper/inverter switching control (yellow banana jacks numbered 1 through 6) to display pulses on a monitor

• All 12 inverter pulses must be verified for each condition listed.

Once the model is running the model, you should check that each pulse...:

This completes the firing pulse unit testing.

• P1 to P4 and P8 to P10 test the software protection hard-coded in the bitstream.
• P5, P6, P7 test the hardware protection made using a board inside the OP8660.

Now using the cable, IGBT chopper/inverter, variable source, inductance and resistance module make the connections as per the circuit in Annex B (for connection plan).

Make sure to use the variable DC source. Note that only the first 4 voltage and current sensors are tested in this model.

FIG 22 MISSING

Once the circuit is complete and running the model, turn ON the power of the IGBT bridge and the variable voltage source.

Turning the rheostat slowly to about 40 volts, use voltage display and make sure to select the right reading.

Looking at the console, all waveforms should be superimposed.

Once the circuit is complete and running the model, turn ON the power of the IGBT bridge and the variable voltage source.

Turning the rheostat slowly to about 40 volts, use voltage display and make sure to select the right reading.

Looking at the console, all waveforms should be superimposed.

In the figure above, we can see the current and the voltage; simulated results are superimposed with the real one.

The same model can be run using the second inverter bridge and using all the other measurements.

Pulses are sent to both inverter firing signal and the group 1 to 4 in the console to indicate which measuring group is used; the first 4 currents and 4 voltages correspond to group 1, the next 4 to group 2 and so on.