Thesis Work - High-bandwidth current Measurement for Wide Band Gap devices

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 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! 

The goal of this thesis is to investigate various methodologies to measure currents with very high bandwidth, originating from switching of the a generation of semiconductors, GaN. Furthermore, to after a theory study, implement these in a double pulse lab set-up existing in the lab at Chalmers, and establish how well various current measurement technologies work for these quick transients.

About this opportunity - Background
Volvo Cars commitment in electrification leads us to take the next step in the development of Electric Propulsion Technology - Power Electronics. The Power Electronics department delivers the best-in class inhouse power conversion designs within Electric Vehicle propulsion system such as DC-AC, AC-DC & DC-DC converters. Currently, we are working on our next generation traction inverter architectures for future vehicle platforms to optimize the efficiency, power density, weight & cost. 

Aiming to increase the driveline efficiency, different WBG devices have been explored with SiC devices being widely accepted and just recently started to be used in inverters. GaN transistors, then even have higher switching speeds, are moving into automotive (as well as other) applications and might be the solution for the next decade, with an even higher potential reduction of energy losses. The key thing for utilizing WBG devices for automotive inverters is to handle their fast-switching behaviors accurately. To measure current for these high bandwidths is fairly tricky. The current viewing resistor, also known as coaxial shunt, is gaining popularity for the double pulse test (a powerful characterization test) to measure the transient current at turn-on and turn-off moments due to its high bandwidth capability. However, its relatively large dimension and intrusive feature bring extra insertion inductance to the circuit, which in principle removes the benefits it brings. The embedded shunt resistor and Rogowski coil solutions have fairly high bandwidth and low parasitic inductance, promising for fast speed switching measurement. Meanwhile, with the availability of high-quality optical isolated probes, SMD shunt resistor solutions are gaining attention for their simplicity and versatility. This thesis project aims to investigate suitable methods for fast transient current measurements both theoretically and by verifying their performances in the lab. 

Scope of the thesis work 
Different measurement techniques are developed in both academic and industrial sides for different applications. In this regard, we are looking for passionate students who are willing to perform detailed studies on suitable methods for fast transient current measurements, for instance in automotive applications, design PCBs and experimentally verify the performance. 
Activities
1.    Study the physics of WBG device fast switching capability
2.    Investigate on different measurement instrument and different measurement methods 
3.    Identify key requirements for fast transient measurement
4.    Design measurement PCBs based on provided half-bridge board
5.    Carry out experiments in the lab and verify the performance.
6.    Summarize and write a technical report.

What you´ll bring
Students with electrical engineering, physics or mathematics background with good grades who like to work in advanced engineering projects are welcome. In addition, skills with circuit design and Schematic/PCB layout design tools (i.e. Altium Designer, KiCAD), with simulation tools (i.e. LTSPICE, MATLAB) are preferred. Students should be available fully on-site.

Duration 
•    30 credits/student
•    January 2025
•    Number of students:  1

How to learn more and apply 
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 10th of December 
Please note that applications via email will not be accepted. 
For questions about the thesis work please contact, Pengpeng Sun at pengpeng.sun@volvocars.com.

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