25 BAE Systems Class 7 truck demo | Dossier E-Mobility Engineering | January/February 2026 Matthews says the integration of the electric drive unit was seamless with the existing axle configuration, and simply required a change of ratio and input position for increased efficiency and durability. All rotating components utilise isolating mounting solutions for minimal transmission of vibration to the structure. A number of other design elements were also integrated to contribute to the noise, vibration and harshness (NVH) characteristics, most notably the speed of the different motors – both traction and accessory. On the demo truck, the speeds of the different accessory components were deliberately lowered to increase efficiency and reduce NVH. “The air brake compressor is a good example,” explains Matthews. “While it’s capable of high speed and flow rates, it was tuned based on the size of the air storage volume. So, it easily achieves the required fill times for Federal Motor Vehicle Safety Standards [FMVSS] but it does so at a slow speed to reduce noise. “Similarly, the fact the maximum speed of the traction motor never exceeds 3500 rpm helps lower NVH from the driveline. Using the grade and load sensing and the ability for secondgear starts, the first shift doesn’t happen until 35 mph in most driving cases, so unless you enter the freeway, that is the only shift event. That makes for very smooth operation.” Control systems One of the most important parts of the solution is the simplified system controls, reducing all the various elements down into a compact and concise two- or three-package set-up. This is composed of the Modular Power Control System (MPCS), the Modular Accessory Power System (MAPS) and the optional System Control Unit (SCU). The MPCS is the heartbeat of the solution, containing an input for charging, a connection to and from the batteries and different outputs for the traction inverter, the high-voltage DC heater port and the DC accessory power output. It also contains an integrated inverter, eliminating the need for any DC cables to leave the box. “The two best options for mounting an inverter are either directly to the motor or with the other power components,” explains Matthews. “We chose the latter due to greater savings in unifying electronics, ensuring electromagnetic interference compatibility and communising the control interface, while also avoiding motor-mounted NVH issues.” The electrification solution results in just two high-voltage power components in two boxes, with the MPCS handling the main power and the MAPS working the accessories. If an OEM wants the convenience of a turnkey solution, the additional SCU can coordinate between the high-voltage power system and the low-voltage vehicle system. In the Class 7 demo, the MAPS has been located forward, under the hood, to power all the accessories, while the MPCS is located mid-ship, making for very short runs of high-voltage cable from the batteries, traction motor and charge port, and Matthews smiles: “The lack of orange cable comes as a welcome surprise to everyone familiar with typical EVs.” The inverter uses SiC, which was not typical when system design began in 2016 and is only now becoming The Modular Power Control System (MPCS) is the control centre of the vehicle, managing power delivery to all the different drive components The Modular Accessory Power System (MAPS) manages the delivery of power to all onboard accessories for maximum efficiency
RkJQdWJsaXNoZXIy MjI2Mzk4