Test and verification of a four-quadrant transducer for HEV applications

This work concerns the design, building and testing of a prototype four-quadrant energy transducer (4QT) for hybrid electric vehicles. The paper describes the test and verification of the 4QT prototype concerning machine parameters, efficiency and thermal performance. The 4QT consists of two different electric radial flux machines: one double rotor machine (DRM) and one conventional machine. In this paper, the conventional machine will simply be referred to as the stator machine (SM). The prototype is designed for a power of 30 kW in each of the double rotor machine and the stator machine. The double rotor machine has an inner rotor with a 3-phase winding fed through sliprings and an outer rotor with inner permanent magnets. The outer rotor has also a set of magnets on its outside and serves therefore as rotor for the stator machine. The input shaft is connected to the inner rotor and the output shaft to the outer rotor. Both machines are designed to work as motors and generators. The 4QT is mounted between the internal combustion engine (ICE) and the final reduction gear in a hybrid vehicle; the ICE is connected to the input shaft and the final gear to the output shaft. The function of the 4QT is to keep the operation of the ICE at optimum efficiency at all speeds and torques required by the vehicle. To do so, the speed is controlled with the DRM and the torque with the SM.