Thesis Work - Evaluation and Optimization of 3 Phase DC Booster Topologies in Electric Vehicles

About this opportunity - Background

As Volvo Cars continues to lead the transition to sustainable mobility, the integration of advanced charging technologies becomes increasingly critical. One such innovation is the DC Boost function, which utilizes the electric vehicle’s inverter and E-machine as a bidirectional DC-DC converter. This enables stepping up a 400V input to charge an 800V high-voltage battery—crucial for compatibility with legacy charging infrastructure. Conversely, it can also step down the voltage for Vehicle-to-Everything (V2X) applications.

Scope of the thesis work

The objective of this thesis is to optimize the current DC Booster topology by thoroughly analyzing the electrical and electromagnetic behavior of the motor drive system, comprising the inverter and E-machine. While conventional booster topologies typically utilize all the phases for the complete power/ state of charge range, this work will investigate the feasibility and performance implications of engaging/ disengaging the three phases to achieve enhanced system optimization and performance efficiency. The investigation will be conducted in two stages. In the first stage, the candidate will concentrate on the modelling and control of a three-phase DC booster. Upon successful completion and satisfactory progress in stage one, the candidate will proceed to the testing phase, where they will validate their findings using a physical test setup.

The ideal candidate should possess a solid understanding of electric machines, power electronics, control systems, and electric propulsion technologies. They should be capable of simulating electric drive systems while accounting for electrical, electronic, and electromagnetic interactions.

Key responsibilities include, but are not limited to:

Stage 1- Simulation
•    Conduct a literature review on E-machine based DC-DC converter topologies.
•    Model the complete electric drive system (battery, inverter, E-machine) in a simulation environment.
•    Develop closed-loop control strategies for bidirectional DC Boost operation and phase balancing.
•    Develop control strategies for engaging/ disengaging the phases based on the power level/ SOC without affecting the system performance.
•    Investigation of CCM to DCM for low power levels.
•    Conduct parametric studies on switching frequency, modulation, and phase utilization.
•    Implementation of an analytical script for estimating the inverter loss.

Stage 2- Testing
•    Loss comparison of multiple-phase operation.
•    Using test data to refine the system-level model.
•    Implement data analysis scripts for automated evaluation of simulation and test data.
•    Support physical testing and validation of the electric drive system.

General
•    Participate in regular stakeholder meetings and technical reviews.
•    Document all findings and present results to Volvo’s technical team.

What you'll bring

We are looking for you within the Master of Science program with Electrical, Power Electronics/ Control Systems and/or Machines. The ideal candidate should possess a solid understanding of control systems, electric machines, power electronics, and electric propulsion technologies. You should be interested in solving challenges individually and in collaboration with a positive mindset. 

You are expected to perform the thesis work on site.

Duration

•    The work will start in January/2026, the exact date can be discussed
•    The duration for this thesis work is 20 weeks.
•    30 academic credits in agreement with your Thesis Advisor at the University
•    This thesis is to be conducted by 1 student