Automotive OEMs commonly house test stands or special facilities to develop, characterize, and test car engines. As hybrid technology plays an increasing role in vehicle designs, OEMs increasingly use such facilities in the development of hybrid-electric propulsion systems for the truck and bus industries. Components of a hybrid-electric propulsion system might include a liquid cooled inverter, a high power-to-weight ratio AC induction electric motor and a reduction gear connected directly to a standard drive shaft and rear axle to provide traction power and regenerative braking.
To ensure such systems manage power efficiently, engineers must accurately measure electrical motor/drivetrain variables such as rotational speed (rpm) and torque. An in-house test stand setup usually comprises a battery simulator, frequency inverter, electric motor, dynamometer, data acquisition system (DAQ), communication interface and a PC in a control area. The dynamometer provides simulated resistance to the system to replicate road situations the electrical motor/drivetrain might encounter, such as when it’s pushing a heavy vehicle up a hill. This arrangement frees engineers from having to drive around in actual vehicles.
Note that while power tests on combustion engines mainly record mechanical signals, the testing of electric motors also necessitates measuring electrical signals between inverter and motor.