Millbrook’s REPS testing software provides complete control of the system for testing, including functionality for the control strategy, real-time graphical representation and data logging. (Berman)

Millbrook’s new California EV testing facility

As electrification gains momentum, the UK-based vehicle-testing firm opens an outpost near Silicon Valley.

The new 25,000 ft2 California test facility run by Millbrook Revolutionary Engineering (MRE) seemed huge to Matt Harris when he first set foot in the building in spring 2019. Six months later, Harris, the test lab manager for MRE, had two test cells in full swing and serving customers. By the end of 2019, four test cells were serving customers. “With the way things have been going, I can now see us even outgrowing this facility,” Harris said.

MRE is riding the wave of vehicle electrification. An increasing percentage of EV activity is based in Northern California, where major OEMs and mobility start-ups are conducting research and development. So Millbrook, which has a global footprint for electric driveline testing, set up shop in Hayward, 25 miles (40.2 km) southeast of San Francisco. The California location augments Millbrook’s testing facilities in Michigan, the United Kingdom and Finland, as well as support offices in Germany and China.

The new facility’s nine employees, including three engineers, operate 24 hours a day. Each of MRE’s four active test cells is equipped with a drive cabinet consisting of a battery simulator (via a DC power supply that can handle a 1,000-volt, 1,200-amp peak). The cabinet also houses one 900-hp inverter, two 500-hp inverters and a suite of electric motors to control speed and torque. Each cell has three dynamometers.

Clients provide a part, say, an electric motor or beam axle. That’s accompanied by a set of test specifications, such as torque and speed points or, for example, a specific load and speed to run until a part fails. Millbrook then provides a whole system to enable the testing of a specific part. A standard test would typically couple an electric motor to a dyno that provides resistance.

Millbrook’s dynos can run at 20,000 rpm, a rate required for EV testing. “A lot of electric motors running in vehicles have a lower power rating because they’re in a small package,” Harris said. “To compensate and get the same torque output to your wheels, the transmissions and gearboxes running now have to be upwards of a 10-to-1 gear ratio, so you’re doubling or even tripling the gear ratio.”

Shift to EV testing
When we visited the facility in November 2019, a transmission was being tested in one of the cells. The client was evaluating the best approach to adding an electric motor as an input, most likely for a hybrid vehicle. The details of specific tests are confidential. Harris said that when he started at Millbrook’s Michigan facility two years ago, about 80% of the tested components were traditional axles, gearboxes and transmission. “Now, I’d say we’re getting close to 60% of testing being done for electrification,” he said. The facility in Hayward is exclusively focused on electrification.

Much of the validation is part of a design and prototype phase. “They want to verify that the mechanical side of their part is working properly,” Harris said. Data derived from multiple channels allows the client to specify the components and integrate them through further stages of validation. On the day we visited, another client was testing two different types of transmissions to compare levels of durability. “A customer will determine what load they need to run for a shortened version of the part’s full life,” Harris explained. “You run higher speeds and torque than you would see in the vehicle.”

That test was scheduled for 25 straight days in 15- or 30-hour profiles. John Sanchez, one of several dyno technicians on staff, was monitoring the activity. The ability for customers to farm out the entire process to Millbrook – from set up and monitoring to testing and breakdown – provides greater speed and flexibility in vehicle development.

More expansion ahead
Harris said that Millbrook’s client base includes OEMs and top-tier suppliers, as well as software companies trying to enter the auto industry. They are trying to gain a better understanding of how their solution can be combined with inverters and motors into the whole drivetrain system. “They’re all working toward the same goal,” Harris said. “Whoever gets there first has a jump on everybody else.”

The heart of Silicon Valley is 30 miles (48.2 km) south of the Hayward-based Millbrook testing facility. High-tech companies working on powertrains for autonomous vehicles might focus on perception or path planning, but still need common electric components for the vehicle. The customer base is also requesting full vehicle testing, something that Millbrook does not currently offer. However, Harris said Millbrook is considering the possibility of adding a fourth dyno to each test cell to accommodate those requests.

Regardless, Millbrook’s decision to open an EV testing facility in Northern California is proving wise. Harris said that the Hayward facility has future goals of growing to 12 test cells, with a larger service team to support expanded operations.

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