Maximum DC-Link Voltage Utilization for Optimal Operation of IPMSM

In hybrid and electrical vehicles the electric components have to be optimized to their limits. The voltage which is delivered by a high-voltage battery should be used fully by the machine. This paper describes the influence of the dc-link voltage on the efficiency and the operating limits of the electric system. For the optimal usage of the dc-link voltage, the converter control has to be extended to the six-step mode. This paper starts with a short introduction describing the electrical components of the developed hybrid vehicle. Afterwards the restrictions due to the voltage limit of the high voltage battery are analyzed. A field oriented control (FOC) is chosen to achieve a high performance control system. However, the field oriented control is not capable to fully utilize the available dc-link voltage. As will be shown it is possible to improve the control strategy of the electrical machine. Especially in applications with limited dc-link voltage and high power density, the new control strategy leads to a better utilization and a higher efficiency of the electrical system.