Upswing in Outsourced EV Testing
As testing for electric commercial-vehicle propulsion systems surges, Drive System Design is rushing to expand testing capabilities to keep up with the demand.
As more commercial-vehicle OEMs choose electrified propulsion systems, the industry is witnessing an “unprecedented surge” in testing, according to Drive System Design (DSD). The electrified powertrain engineering consultancy says that OEMs and suppliers are running into test-cell capacity issues and are increasingly outsourcing to bring new electric propulsion systems to market.
To keep up with significant growth in the electrified commercial-truck space, DSD is adding additional equipment to test motors and drives for Class 7 and 8 trucks at its U.S. technical center in Farmington Hills, Mich. “We will soon have the capability to test motors up to 350 kW and speeds right up to 20,000 rpm,” Matt Hole, DSD vice president of engineering, told SAE Media.
The company’s U.S. facilities can accommodate up to Class 4 CV electric systems, with the U.K. spanning up to Class 7. Hole said with DSD’s core expertise and focus upon motor and drive design in the CV space, the company does not see an immediate need to be able to test complete Class 7 or 8 axle systems at its U.S. facility, as it does for 3-in-1 automotive and trucks up to Class 4. “We have existing facilities that enable us to test motors for up to Class 7 trucks,” said Hole. “Our new developments will future-proof these test fixtures as manufacturers potentially increase motor speeds in the hunt for improved efficiency.”
Future plans for DSD’s U.S. technical center include adding additional equipment to test motors and drives for Class 8 trucks. “The trend we see at the Class 7 or 8 level is to use multiple motors and divide the power between them, making each motor smaller,” Hole explained. “That puts the individual motor power well within the capabilities of our existing or planned equipment, enabling us to do motor efficiency, thermal and performance characterization testing and development.”
The company’s test cells and state-of-the-art equipment are flexible enough to accommodate a wide variety of applications including tractor and electrified implements, and an array of other markets. “The e-machine market in agriculture and mining as well as material handling is a well-established market, with a sizeable head start against the on-highway market,” Hole said. DSD sees an increasing number of electrification inquiries from these segments, where before it traditionally served as a turnkey hydraulic controls supplier.
Keeping up with demand
DSD’s test cells in Farmington Hills are extremely busy, and the company recently announced the expansion of its U.K. technical center’s test facilities with the addition of two new test cells for high-performance hybrid axles and e-machines. This demand is all related to the development of all-new EV propulsion systems.
Currently the company’s U.S. technical center features a 3E test rig with a high-power battery emulator for electric and hybrid vehicle development and hardware in the loop (HIL) testing. It also houses a hydraulic test stand for hydraulic valve body development, a 2/1E transmission efficiency rig, and a 1E spin/tilt rig providing enhanced lubrication flow analysis capability.
Hole said the company’s U.S. facility is booked about four to five months out for its larger loaded dynos. For some of the smaller dynos used for lubrication development and efficiency characterization, the company has limited availability over the coming months. “This is a time where these types of non-commodity, development partner facilities are under great demand in Metro Detroit and across the whole U.S.,” Hole said.
So, is this testing surge the new normal? “We definitely see a continuation of the demand for the foreseeable future and are planning further significant investments throughout the next year or so to accommodate this demand,” Hole shared. “We also see a strong drive towards higher voltages and also additional power sources like hydrogen.”
DSD currently does not have its own testing equipment for fuel cells but has partners it can leverage for this type of product today. “We think that hydrogen fuel cells will be significant in the heavy truck market, and the need to have the facilities to be able to test the complete system is something we are watching carefully as we look toward the future,” he said.
The engineering team at DSD has learned many lessons through the course of testing and development for electric propulsion. One notable insight is not to underestimate the challenge of testing motors at high-speed. “It’s a significant mechanical challenge with several modes of vibration that you need to avoid in order to achieve successful data,” Hole said.
Being mindful of the system limits when planning the testing also is key. “Our customers regularly ask us to run the types of accelerated testing that have become common practice in engine and transmission development,” Hole explained. “This can mean the motors within the electric drive unit are operating outside of a comfortable window and failures are therefore common.”
Since DSD specializes in the rapid engineering and development of complete electrified propulsion systems, its facilities allow a customer to test the motor or transmission on their own, and then the full system as a unit. Hole recommends allowing plenty of time to test a whole system. “For a 3-in-1 automotive system, it is critical,” he said. “In the CV space, especially as we’re approaching Class 7, it’s not quite as important due to reduced levels of integration between inverter, motor and transmission.”
DSD’s approach to testing mirrors its design and analysis philosophy, operating at a system level. “Combined testing and development of the motor and inverter is something we always recommend to properly assess efficiency and to understand thermal behavior,” Hole said. Having the proper equipment – such as a highly capable power analyzer that DSD recently invested in – also is critical. The new analyzer allows engineers to accurately measure electrical power going in compared to mechanical power coming out, while synchronously logging high-speed accelerometer data to assess NVH and monitor system health.
The bulk of the company’s customers are established Tier 1 suppliers in automotive and commercial truck markets, Hole shared, as well as OEMs that are focusing on the electrification space. Defense, aerospace and marine projects supplement those, and start-ups also have employed its services. “We are able to swiftly help them design and develop their first product,” he said.