Mark McDonnell of Protean Electric describes how using NI LabVIEW software and NI CompactDAQ integrated hardware dramatically reduced the time and cost required to develop an in-wheel electric drive system.
The Protean Drive system is the most advanced in-wheel electric drive system for hybrid and battery-electric vehicles (BEVs) in the world. Protean Electric, a leading clean technology company, developed this revolutionary propulsion system that delivers many advantages compared with existing hybrid vehicle platforms. The integrated motor and inverter in the Protean Drive system provides the high power density and torque density required for electrification of full-size saloons and SUVs without compromising vehicle performance or cost. It also enables full regenerative braking to be implemented in normal driving to recapture large amounts of kinetic energy that is subsequently fed back into the battery. The system is packaged in-wheel, which saves space in the vehicle for passengers and batteries, and eliminates all external transmission components. It also provides advanced vehicle dynamics through the independent torque control of each wheel.
Protean Electric works closely with many major vehicle manufacturers around the world, and our UK-based design facility is used for prototyping, testing and low-volume production of the Protean Drive system.
Developing our innovative drive system requires a great deal of careful testing and characterising to cover every performance aspect of our integrated motor and inverter. Characterisation is performed on our in-house dynamometers and involves the interaction of a number of different systems for control and data acquisition. Both the Protean Drive system and our dynamometers are separately controlled via controller area networks (CAN), and during our testing we collect a large amount of data from a wide variety of inputs including multiple CAN channels, temperatures, pressures, voltages, currents and digital inputs.
Our aim was to automate this testing to help reduce the time our engineers spend performing characterisation work. Manually testing every aspect of both driving and regenerative braking performance across the complete speed and load range using a variety of third-party products would take up to two weeks of full-time work by an engineer. This would then be followed by up to a week spent processing and compiling all of the logged data from the various sources. Each new product has to be characterised on a large number of samples to ensure repeatability and to get a good average of the performance. Altogether, this would amount to several months of costly engineering time.
Our solution was to use the integrated hardware and software offered by National Instruments to dramatically reduce both time and costs through automation. LabVIEW was an obvious choice due to its widespread use in the industry and the large range of compatible hardware available both directly from National Instruments and offered by third-party manufacturers.
How LabVIEW was used
We used LabVIEW to create a fully automated control program capable of independently controlling both the Protean Drive system and the dynamometer via CAN, as well as providing integrated fault monitoring and data logging. It was easy to integrate with our existing third-party CAN hardware through the use of readily available LabVIEW drivers, which reduced development time dramatically.
Our LabVIEW control program enables the user to create predefined test cycles in spreadsheet format that can be loaded and run when required. This includes options for looping or conditional execution of certain sections of the cycle based on any of the available inputs. Using the LabVIEW PID and Fuzzy Logic Toolkit we were able to have automatic control to set torque, speed, temperature or any other measured variable. To make the system fully automated we needed to include an error handling system that could monitor for many types of faults and shut the equipment down safely in the event of any failure. This means that the equipment can be left to run completely unattended while our engineers are free to do other things.
Data logging was added through the use of an NI CompactDAQ system and a selection of available C Series modules. The modular nature of NI CompactDAQ and the wide range of configuration options available helped us connect all of our temperatures, voltages and digital inputs into just one piece of equipment. We used the tight software and hardware integration between LabVIEW and the NI CompactDAQ system to log all the different types of data through a single program, making it much easier to manage. The LabVIEW program collects the data and automatically processes and organises it while the test is running, which removes the need for manual processing at the end. Using the LabVIEW Report Generation Toolkit, the system delivers completed reports in a standard Windows format that are ready to present to managers and customers alike.
The automated, integrated system we created using LabVIEW software and NI CompactDAQ hardware revolutionised our product testing. Testing that used to require up to three weeks can now be completed in just 12 hours, completely unmanned and automated. This has literally saved us months of engineers' time. We are also able to run standard automotive industry drive cycles with rapid transient changes in speed and torque that could never have been controlled manually.
In addition to this, the data that we are collecting is much more detailed than ever before. It is also much more accurate and repeatable because every test is now performed exactly the same way instead of being open to operator influence.
With the recent purchase of additional NI CompactDAQ hardware, we are now in the process of expanding the same system to all of our test rigs as well as our end-of-line production testing. The NI Developer Suite helps us easily deploy our software package through the included code distribution tools, meaning that expansion is simply a case of installing the control software and plugging in an NI CompactDAQ.