A brushless motor drive with sensorless control for commercial vehicle hydraulic pumps

The paper describes the electronic design of a brushless motor drive powering a hydraulic Motor-Pump-Unit (MPU) for automotive applications. The full MPU consists of a Permanent Magnet (PM) brushless motor, a three-phase MOSFET inverter with digital control and a gear pump for the hydraulic circuit. The MPU designed in this project is characterized by low voltage supply and high hydraulic output power, so that the choice of power electronic components have been particularly challenging, mainly because of conflicting requirements in terms of current rating and total cost. The experimental results obtained with a first MPU prototype demonstrate that the weak point of the complete mechatronic design is related to the volumetric efficiency of the gear pump, while the power converter and brushless motor assembly is characterized by an acceptable efficiency.