Thesis Work - High Voltage System/Battery Impedance measurement techniques i Göteborg

Welcome to explore the world of Volvo Cars by writing your thesis with us! As a thesis worker in our organization, you are supported by a supervisor who follows you during your project. All thesis projects are arranged in business-critical areas and therefore you will be able to contribute to our company purpose – providing freedom to move in a safe, sustainable and personal way – from day one!

In Electric Vehicles (EVs), High-Voltage components interact in a complex manner. The switching in power electronics generated ripple and generates electromagnetic fields, disturbing other components and degrade their performance. So, it is essential to understand and design components from early stage of the project to reduce price and decrease the development time.

In order to design the and develop electronic components, it is important to know the system impedance of the high-voltage system used for the vehicle propulsion. The impedance is needed from low frequencies up to high frequencies in the EMC range. With the measurements it is possible to create circuit models that can be used to optimize the driveline and electric power system. Also, the impedance of the High-Voltage battery is an important variant that can be used to estimate the state of the battery, state of charge, life expectancy and such. However, the methods and instruments currently available are developed to measure the impedance of the Low-voltage system, battery cell modules and small battery packs and not for the EVs High-Voltage system/battery pack which is rated up to 800V.

Scope

The objective of the thesis work is to investigate different methods to measure the High voltage system and /or battery impedance.

Main tasks:

• Conduct literature review of impedance measurement of electric High-Voltage systems in EVs.
• Investigate different impedance measurement techniques for High Voltage System and/or battery. This can include using a Vector Network Analyzer with an electric interface device that provides electric insulation between the VNA and the high-voltage system/component. Another alternative is to use the already existing disturbances/noise in the electric system generated by the electric drives.
• Develop the hardware (electric interface device) which can be used with the measurement instruments and evaluate the results with simulation data. The electric interface device needs to provide electric isolation between the high-voltage circuit and the measurement instrument. The device may consist of capacitors and/or transformers.
• Perform tests with the measurement methods on the complete high-voltage electric system or on a traction battery.
• Evaluate the test results and compare the methods’ performances.
• Create electric circuit models and fit them to the measurements (if time permits)

• Electric power engineering studies or equivalent
• Matlab and model-based development
• Knowledge of PCB design and CAD software tools is meritorious.
• Electric circuit modelling software knowledge, e.g. LTSpice or PSpice
• Good English skills

• Project to start in January 2024
• The duration for this thesis work is 20 weeks.
• 30 ECTS (academic credits) if in agreement with your Thesis Advisor in University
• This thesis is suitable for up to 2 students working in pair.
• The work will be performed in Gothenburg.

We’d love to receive and review your application. Selection will be ongoing during the application period, so do not hesitate to send in your application. Attach your CV and personal letter stating your interests within the given area and your thoughts and credentials.

Apply as soon as possible but no later than 2023-11-10.

Please note that applications via email will not be accepted.

If you want more information about the project or simply learn a bit more about the team, please reach out to:

Manager Fredrik Niklasson (fredrik.niklasson.2@volvocars.com),

Supervisors: Anders Lasson (Anders.Lasson@volvocars.com) and Divyaraj Gadhavi (Divyaraj.Gadhavi@volvocars.com)

Everything we do starts with people. Our purpose is to provide freedom to move, in a personal, sustainable and safe way. We are committed to simplifying our customers’ lives by offering better technology solutions that improve their impact on the world and bringing the most advanced mobility innovations to protect them, their loved ones and the people around them. 

Volvo Cars’ continued success is the result of a collaborative, diverse, and inclusive working environment. The people of Volvo Cars are committed to making a difference in our world. Today, we are one of the most well-known and respected car brands, with over 40,000 employees across the globe. We believe in bringing out the best in each other and harnessing the true power of people. At Volvo Cars your career is designed around your talents and aspirations so you can reach your full potential. Join us on a journey of a lifetime as we create safety, autonomous driving and electrification technologies of tomorrow.