DFIG Motor Kit Power Up Calibration and Test

Calibration is the first step when using the OP5600-OP8660 setup.

Because the OP8660 outputs ±10V, it should be rescaled in the model. There may also be a small offset due to the ADC, which can be corrected by adding offset and gain in the model.

This exercise describes how to properly power-up the system and to ensure the calibration of all current/voltage readings of the OP8660.

Allow the OP8660 system about 10-15 minutes to warm up before calibrating. Default values may change with time, heat or even humidity, but can easily be calibrated using a software model.

Material Needed

• Variable DC source (8821)
• Resistance
• Measurement (OP8660)

POWER UP

• Put the power switches at the back of each housing in the On position
• Make sure that the RT-LAB MetaController is active on your host
• Open TestDrive and unpack the desired model

CALIBRATION

Calibration depends on the value(s) provided by the user, which are then read by the system, which calculates its gain and offset to provide an accurate reading.

In order to complete this task, one display shows the offset that should be applied to each of the 16 inputs, and the other shows the gain for each input.

The user should wait for the value to stabilize, and should also try different voltage values to cover the whole range of the current and voltage acquisition.

Detailed Calibration How-to

• Connect the variable voltage source, the current reading and a resistance in series (as shown).
• Although the figure shows the LabVolt Power Supply, it is recommended to use another voltage source that provides a more stable voltage source for calibration.
• Connect the voltage measurement at the source as shown. Refer to Device Connection Schematics for connection.

1. Calibrate the voltage offset (calibration tab of the main screen):
   • Set the power supply voltage to zero
   • Enter “0” in the Offset field
   • Click to activate Calculated Gains
   • In the Voltage measurement box, find the channel that corresponds to the channel currently connected. (For the circuit connected as above, it is channel 1).
   • Then turn on its corresponding switch to calibrate the offset
2. Calibrate the current offset:
   • Set the power supply voltage to zero
   • Enter the value of zero in the Offset box circled in blue in figure 2
   • Click to activate Calculated Gains.
   • In the Current measurement, find the channel that corresponds to the channel that is currently connected. (For the circuit connected like figure 1, it is channel 1).
   • Then turn its corresponding switch on to calibrate the offset
3. Calibrate the voltage:
   • Set the power supply voltage to a non-zero value (eg. 30V)
   • Enter the set voltage value (e.g., 30) in the Gain box field 
   • Click to activate Calculated Gains
   • In the Voltage measurement box, find the channel that corresponds to the channel that is currently connected. (For the circuit connected like figure 1, it is channel 1).
   • Then turn on its corresponding switch to calibrate the gain
4. Calibrate the current gain:
   • Set the power supply voltage to a non-zero value (eg. 30V) and connect it to the desired channel on the OP8660 (using the banana jack cables)
   • Calculate the current depending on the chosen resistor using Ohms. In Figure 1, the current is 1A given a voltage of 30V and a resistance load of 30ohms
   • Enter the calculated current in the Gain box
   • Click to activate Calculated Gains
   • In the Current measurement box, find the channel that corresponds to the channel that is currently connected and click the switch next to its corresponding channel number to calibrate the gain