Creating Compensation Values with Temperature Parameters

Create compensation files that include temperature parameters when performing tests with temperature monitoring.

If you have multiple instances of the same DUT, create one compensation file for all DUTs. Create or update a compensation file when you complete any of the following actions:
  • Change the excitation current
  • Add more frequencies to the frequency sweep
  • Change the maximum or nominal voltage
  • Move or adjust the cabling to the fixture
  • Re-cable or replace the fixture
  • Change the SMU that is taking the measurement
Note You are not required to recalculate the compensation values if the SMU runs self-calibration.
Before you begin, create a configuration file for the EIS test or the ACIR test.

Equipment

  • PXIe-4139
  • Compensation device in place of the DUT
  1. Use the NI Example Finder to open <Test type> Create or Override Compensation Files with Temperature.vi.
    1. In the LabVIEW window, select Help » Find Examples.
      The NI Example Finder window loads.
    2. Select Toolkits and Modules » Battery Cell Quality » <Test type> Create or Override Compensation Files with Temperature.vi.
      The front panel of the VI loads.
  2. On the front panel of the VI, select the SMU resource from the HW Resource Name and Channels control.
    Note NI supports the PXIe-4139 (40 W) and PXIe-4139 (20 W) SMUs.
  3. Optional: If you want the SMU to perform self-calibration, enable self-calibration on the front panel.
    Note You must disconnect the DUT during self-calibration. If the DUT is connected to the SMU during self-calibration, an error occurs.
  4. Update the test parameters to use the same settings you use for the test.
    If you are using a configuration file, you must specify the same Compensation Method when creating the configuration file.
    OptionDescription
    Enter the test parameters for an EIS test.
    1. Configure the Frequency Sweep Characteristics. Each entry on the Frequency Sweep Characteristics array defines the parameters that the VI uses to generate a sine wave. Refer to Configuring the Frequency Sweep Characteristics for EIS Measurements for more information about each parameter.
      1. Select the number of tests.
      2. Select the Frequency (Hz). The frequency is limited by the number of arrays you selected.
      3. Select the Current Amplitude (A).
      4. Select the Number of Periods.
    2. Select the Voltage Limit Hi (V).
    3. Select the Nominal DUT Voltage (V).
    4. Select the Compensation Method.
    5. Select the Power Line Frequency.
    Enter the test parameters for an ACIR test.
    1. Select a Nominal DUT Voltage (V).
    2. Select a Voltage Limit Hi (V).
    3. Select a Current Amplitude (A).
    4. Select a Number of Periods.
    5. Select a Compensation Method.
    6. Select a Power Line Frequency.
  5. Optional: Select a Known Impedance Table.

    If you select Short Compensation for the compensation method, you can use a small known resistor in the jig as a compensation device. Define a Known Impedance Table. Then, provide the path to a Known Impedance Table so that the compensation file records only the difference from the known values. The saved compensation reflects the impedance of the jig, which must be compensated during measurement.

  6. Update the Temperature Parameters to use the same settings you use for the test.
    1. Select the Thermocouple Resource Name.
      NI recommends using the PXIe-4353.
    2. Select the CJC source.
      If you use the PXIe-4353, NI recommends using the Built-In option for cold junction compensation (CJC). The built-in CJC uses an internal temperature sensor that is located at the terminal block of the connector device. The temperature sensor measures the cold junction temperature (TCJ). TCJ is used with the thermocouple voltage reading to calculate the hot junction temperature (THJ) using the Seedbeck effect.
    3. Select the Units at which to monitor the temperature.
    4. Select the Thermocouple type.
      Table 11. Common Thermocouple Types
      Type Materials Approximate Temperature Range Characteristics
      B Platinum-rhodium (30%)/platinum-rhodium (6%) 0 ℃ to 1700 ℃ Good for high temperatures, stable, expensive.
      E Nickel-chromium/constantan -200 ℃ to 900 ℃ High output, good for low temperatures.
      J Iron/constantan -40 ℃ to 750 ℃ Low cost, limited range due to iron oxidation.
      K Nickel-chromium/nickel-aluminum -200 ℃ to 1260 ℃ Most common, general purpose.
      N Nicrosil/nisil -200 ℃ to 1300 ℃ Stable at high temperatures, better than K in harsh environments.
      R Platinum/platinum-rhodium (13%) 0 ℃ to 1600 ℃ Very stable, used in labs and high-temperature processes.
      S Platinum/platinum-rhodium (10%) 0 ℃ to 1600 ℃ Similar to R, used in industry and labs.
      T Copper/constantan -200 ℃ to 350 ℃ Accurate at low temps, good for cryogenics.
    5. Select the Minimum value for the expected temperature range of the input signal.
    6. Select the Maximum value for the expected temperature range of the input signal.
    7. Enter the Temperature Delta.
  7. Place the short compensation device in the fixture.
    Note NI does not provide a compensation device. You must design and create a device that is based on the guidelines provided in Improving Measurement Accuracy with Compensation.
  8. Click Run.
    The VI creates a file of compensation values in the following folder: C:\Users\Public\Documents\National Instruments\NI-Cell Quality\Compensation.

    The compensation file name has the following structure: z_Short_<smu-serial-number>_Ch0.json.

Ensure that you select the same temperature parameters that you defined in the compensation file when running tests with temperature monitoring.