Variable DC-link Control Strategy for Maximum Efficiency of Traction Motor Drives

This work proposes an optimized control strategy for online adapting the DC-link voltage in a traction motor drive. In the considered vehicle architecture, a DC/DC converter boosts the battery voltage (rated 400 V) to a controlled DC-link, which feeds the traction inverter. The amplitude of the DC-link is online varied depending on the drive speed and torque conditions to minimize the power losses in the DC/DC converter and in the traction inverter. The switching losses in both the converters are reduced by minimizing the DC-link voltage without affecting the motor control performance. The proposed DC-link adaptation technique is almost independent of the motor parameters and adopted torque/speed control strategy, therefore it can be adopted in a wide number of applications. Moreover, it requires minimal calibration effort.