Mapping an Optimum DC-Link Voltage across the Entire SiC-Based EV Drive Regions Using a Synchronous Boost DC-DC Converter 2024-01-2218

When designing an electric vehicle (EV) traction system, overcoming the issues arising from the variations in the battery voltage due to the state of charge (SoC) is critical, which otherwise can lead to a deterioration of the powertrain energy efficiency and overall drive performance. However, systems are typically documented under fixed voltage and temperature conditions, potentially lacking comprehensive specifications that account for these variations across the entire range of the vehicle operating regions. To tackle this challenge, this paper seeks to adjust an optimal DC-link voltage across the complete range of drive operating conditions by integrating a DC-DC converter into the powertrain, thereby enhancing powertrain efficiency. This involves conducting a comprehensive analysis of power losses in the power electronics of a connected converter-inverter system considering the temperature variations, along with machine losses, accounting for variable DC-link voltages. The results reveal that the inclusion of a DC-DC converter into a powertrain is advantageous, particularly for low battery terminal voltages. Consequently, the powertrain system, incorporating a DC-DC boost converter, exhibits lower total loss values, with a difference of up to 5 kW loss difference for high-speed, low-torque regions compared to the case when not incorporating the DC-DC converter.