Test_Equipment_Control

Controlling Various Lab Test Equipment

• Battery Testing (Capacity, Internal Resistance, SoC-OCV, SoC-IR)
• DC-DC Converter Testing (Efficiency across input voltage and output loads)

For an overview of what this program can do, check out this post: https://a2delectronics.ca/2023/05/04/battery-test-with-standard-lab-equipment/

Setup

Prerequisites:

• Tested with Python 3.9.10. Download and install it from here: (https://www.python.org/downloads/release/python-3910/)

  • Make sure to check 'add Python to PATH' when installing, and 'Disable PATH Length Limit'
  • If you want to use a virtual environment to store all the packages and not have package version conflicts with other programs on your system, set that up now.
    • Navigate to the Test_Equipment_Control directory and use the following to create a virtual environment:
    • Create the venv: python -m venv venv --prompt="batlab"
    • Activate the venv (must be done every time you use the script: venv\Scripts\activate
    • More details on virtual environments here: https://realpython.com/python-virtual-environments-a-primer/

• Keysight Instrument Control Bundle (https://www.keysight.com/ca/en/lib/software-detail/computer-software/keysight-instrument-control-bundle-download-1184883.html) We need IO Libraries Suite and Command Expert (.NET 3.5 may be required for Command Expert: https://dotnet.microsoft.com/en-us/download/dotnet-framework/net35-sp1)

• NI VISA (https://www.ni.com/en-ca/support/downloads/drivers/download.ni-visa.html#460225)

• To install all the required python packages

  • Open a command line in the Test_Equipment_Control folder and run pip install -r requirements.txt

• You may need to install libusb (backend for pyusb): pyusb/pyusb#120 (comment) (You'll need 7-zip to unzip it: https://www.7-zip.org/)

• The command python -m visa info should give something like this at the end of the response, where ivi and py (ASRL and USB) backends are both available:

PyVISA Version: 1.11.3

Backends:
   ivi:
      Version: 1.11.3 (bundled with PyVISA)
      #1: C:\Windows\system32\visa32.dll:
         found by: auto
         bitness: 64
         Vendor: National Instruments
         Impl. Version: National Instruments
         Spec. Version: National Instruments
      #2: C:\Windows\system32\visa64.dll:
         found by: auto
         bitness: 64
         Vendor: National Instruments
         Impl. Version: National Instruments
         Spec. Version: National Instruments
   py:
      Version: 0.5.2
      ASRL INSTR: Available via PySerial (3.5)
      USB INSTR: Available via PyUSB (1.1.0). Backend: libusb1
      USB RAW: Available via PyUSB (1.1.0). Backend: libusb1
      TCPIP INSTR: Available
      TCPIP SOCKET: Available

We also need to comment out a few lines in the included libraries from adafruit.

1. Find where the python packages get installed ("Users->UserName->AppData->Local->Programs->Python->Python39->Lib->site-packages" for me, not using a virtual environment) and find the folder adafruit_blinka->microcontroller->mcp2221
2. Adafruit packages are amazing, but this one tries to create an object and creates an error when it can't find an mcp2221 device.
3. In the file mcp2221.py, comment out the last line #mcp2221 = MCP2221() that creates the mcp2221 object.
4. In the file i2c.py, comment out the first line #from .mcp2221 import mcp2221 that tries to import that object that was created.

Testing Connection:

To make sure that your computer can see the devices you connect, run Keysight Connection Expert and see which devices are available.
You can open the Interactive IO and send the query \*IDN? to get the device's identification.
If Keysight Connection Expert can see it, then the drivers are installed and you should be able to connect from the python script.

Running Tests

Testing Batteries:

Run battery_test.py from command line.

1. File->Scan resources
   • This checks all the backends for available equipment. Some equipment previously connected to but not available now may be recognized.
2. File->Connect to equipment
   • Choose the type and model of equipment that you want to connect to. Fake equipment is available for playing around with the software.
   • If you connect equipment with multiple channels (e.g. A2D 64CH DAQ), then here you connect only to the board.
3. Assign Equipment to channel
   • Equipment that you have previously connected to will be available to assign to the channel.
   • For equipment with multiple channels (e.g. A2D 64CH DAQ), then here you must select the channel of the equipment to assign to the test channel as well.
   • An 'idle_test' will be started that will measure voltage and current using the connected equipment.
   • Ensure voltage shown matches the battery voltage expected (if one is connected).
4. Configure Test
   • Choose and configure the type of Test you want to do.
   • A Test is made up of 1 or more Cycles.
   • A Cycle is made up of 1 or more Steps.
   • A Step contains:
     1. Configuration Info. For sources and sinks (power supplies and electronic loads).
     2. Step End Conditions. If the step end condition is met, then the next step starts.
     3. Cycle End Limits. If these settings are exceeded, the Cycle ends immediately and the next Cycle starts.
     4. Safety Limits. If these settings are exceeded, the Test ends immediately.
   • All Cycle types chosen in the GUI are converted to Steps before they are run.
5. Start Test
   • The 'idle_test' that was running will be stopped and the configured test will start.
   • The test can be manually stopped at any time with the 'Stop Test' button.
   • If any of the safety settings are exceeded, then the test will stop automatically.
   • Each Cycle gets its own log file.

The setups and tests can be exported and imported (.json format) for easy reconfiguration when restarting the software.

See the results with GraphIV.py. Graphs and stats (capacity_ah, capacity_wh, max temperature, etc.) for each cycle can be generated.

Testing DC-DC Converters:

Run dc_dc_test.py from command line

• Allows setting up a test with psu on input, eload on output.
• Sweeps a range of output currents and a range of input voltages.

An efficiency graph can be generated from the data with DC_DC_Graph.py

Testing solar panels by sweeping an e-load in CV mode:

Run Eload_cv_sweep.py from command line
See results (solar panel IV curve with MPP marked) with Eload_cv_sweep.py

Measuring a bunch of thermistors with A2D 64CH DAQ:

Using battery_test.py connect to the A2D 64CH DAQ, and a Fake DMM. The config file for the A2D 64CH DAQ should be set up following the 'A2D_DAQ_Config_All_Thermistor_NXRT15XV.csv' format, using Steinhart-Hart coefficienct specific to your thermistor. Assign the Fake DMM as a separate voltage measurement equipment, and the A2D 64CH DAQ channels you want to measure as additional DMMs to measure temperature for the channel. Configure a test for the channel, using a single rest step for the amount of time you want to log the thermistors for. Make sure to change the safety_time_s as well. Setting safety_time_s to 0 will disable the time safety check. Start the test, and a log will be created with a fake voltage measurement as well as all the temperature channels.

Quick measurements with a DMM:

Run Measurement_Script.py from command line.
Choose to measure voltage, current, or temperature, the number of measurements to take, and the delay before starting the measurements.
Measurements will be printed out in the console.

TODO List

• Why does it take so long to get the instrument idns when connecting equipment?
• For tests with more than 1 channel, draw lines between the blocks on the UI to separate them better.
• Make the CH0, CH1 headings larger
• GraphIV.py - Single IR Processing - if we have enough data points for each step, apply some statistical processing (drop outliers, try and account for capacity)
• GraphIV.py - Allow processing of a bunch of different cell folders at a time. (e.g. ran the same test on 100 different cells and process the data all at once instead of clicking through all the folders).
  • Need to distinguish between real log csvs and other csvs.
• Make the cycles a dictionary instead of just a list of steps so we can store other information in them (e.g. Cycle Type, eq required, etc.)
• There are way too many queues and processes in the MainWindow. Consolidate them and make a better messaging system
• Make 'charge_discharge_control' file into a class
• Change naming of cycle_settings_list_of_lists in charge_discharge_control to reflect the cycle and step structure.
• Double-check commands where possible? e.g. send output on command, then check status of output.
• View equipment connections and change settings per instrument instead of having to setup everything again - e.g. remote sense.
• Create a 'remove channel' button
• Make GUIs better with drop-downs and checkboxes
  • PSU, Eload, DMM selections should all happen on a single page with a dropdown for each equipment type.
  • Step cycles should have dropdowns for all text fields instead of requiring to know what goes there (voltage_v, current_a, etc.)
• Add a way to get output state of all equipment so we can remove redundant disable and waits.
• Create safety limits for extra measurement devices - e.g. cell monitors on multi-cell battery packs, temperature sensors.
• Make a way to add temperature control of the ambient temp through heaters - heaters will have external controller, just need to pass setpoint.
• Create a way to 'simulate a cell', connect multiple pieces of 'fake' equipment to a 'battery equivalent circuit'
• Show which safety error was hit on GUI instead of needing to search through the logs?
• Add a button on the GUI to advance to the next cycle or step
• Add support for range switching of eloads between different cycles (e.g. use 4A range for a 1A discharge and 40A range for 5A discharge).
• Allow 1 device to have multiple uses (e.g. a relay board and voltage/current/temperature monitor all in one) - will be easier when all equipment is virtual
• Add features to relay board to define which inputs could connect to which outputs (e.g. share 2 power supplies and 2 eloads between 4 cells). (Board definition file for different relay boards?)
• Add support for 'scheduling' different cycles when we have relay boards connected - e.g. share an eload and wait for other cell to be done with it.
• Properly synchronize voltage and current measurements (only available on certain equipment). - Low Priority
• finish adding ICA: smooth data before analysis
• HPPC test profile creation gui
• Allow different measurement rates for different equipment - temperature can be measured more slowly

TODO List Graveyard

• DONE - Allow adding another cycle types to test configuration GUI - e.g. Rest then Single IR Test
• DONE - Make sure to take a '0 current' reading at the start of every test to determine a rough starting SoC from SoC-OCV map. Useful for post-processing data.
• DONE - Do not allow starting a test when a safety error exists.
• DONE - Create an 'add channel' button
• DONE - Repeated IR Discharge Test: Fix charge safety time, add rest after discharge
• DONE - Flush queues after and before idle control cycle
  • Will cause issues with multiple channels accessing the same queues?
• DONE - Show fake equipment even when no resources are available
• DONE - Common equipment selection template - instead of a for loop and if statements in each device file
• DONE - Make all instruments 'virtual' - e.g. controlled globally and not by the individual battery test channel processes. This opens the door to scheduled use of equipment, sharing between channels, and using all channels of multi channel devices.
• DONE - cell logs go in a folder with the cell name
• DONE - Separate safety conditions for each channel from end cycle conditions
• DONE - Add safety conditions to all types of cycles (just make them all use step at the core)
• DONE - Add a way to show a 'charge' or 'discharge' or 'ir test' instead of just showing 'step'
• DONE - Change log file name to show which cycle_display name instead of just date, time, and cell name, overall cycle type
• DONE - Add WARNING on the GUI if a safety setting was hit
• DONE - Add internal resistance test through the step profiles
• DONE - Add capability to test SoC vs Internal Resistance
• DONE - Add parallel eloads ability to draw more power
• DONE - Add ability to control and interact with the A2D DAQ
• DONE - create auto-recognizing equipment profiles
  • DONE - choose instruments based on IDN? response instead of visa resource name.
  • DONE - Save equipment connections to a json file
• DONE - change charge and discharge to have the psu or eload passed in to the function
• DONE - add multiple end conditions (time, current, voltage) to each step
• DONE - charge/discharge profiles from a file
• DONE - Add ability to choose different voltage measurement equipment (e.g. DMM instead of eload or PSU for voltage).
• DONE - Add ability to choose different current measurement equipment
• DONE - use multiple processes to have multiple tests running at the same time
• DONE - Add support for a current profile - or a number of steps
• DONE - Add 'safety limits' for voltage, time, current
• DONE - Ensure Step functions use minimal equipment - e.g. only power supply when charging or only eload when discharging.