Metrological Optimization of Nonlinear Frequency Response Analysis

Application Deadline: 
Tuesday, February 28, 2017

The Braunschweig International Graduate School of Metrology together with the Technical Cooperation of PTB offer the opportunity for currently two PhD scholarships each year for students engaged in natural sciences or engineering. The funding is provided by the German Federal Ministry for Economic Cooperation and Development (BMZ) to support developing and emerging countries (please see full list of partner countries) in the field of quality infrastructure. Initially, funding will be granted for one year. Given that it typically takes three years to complete a doctoral thesis PTB will be committed to obtain a follow-up funding. The size of the grants is comparable to grants provided by the German Academic Exchange Service (DAAD). The scholarships will be located at TU Braunschweig.

An excellent academic record and fluent English are prerequisites; skills in the German language are welcome. The submission should include CV, transcripts of the most important documents of professional qualification and a letter of application. B-IGSM promotes the professional equality of women and men and is thus especially interested in applications from women. Disabled persons will be given priority if they have the same occupational aptitude. Any granting of a scholarship has to be approved by the International Office of TU Braunschweig taking into account the Promotionsordnung (PhD Regulations) of the respective faculty where the scholarship will be located.

Please note that any application needs to be submitted via the application portal of B-IGSM.

Metrological Optimization of Nonlinear Frequency Response Analysis

High energy Li-ion batteries are most important energy storage devices for electric traction within the foreseeable future. The Institute of Energy and Process Systems Engineering of the TU Braunschweig has applied Nonlinear Frequency Responses Analysis (NFRA) to Lithium-Ion-Batteries to characterize the properties and dynamics of the battery. In comparison to the established and common dynamic measurement method of Electrochemical Impedance Spectroscopy (EIS) higher AC excitation current amplitudes can be accessed with NFRA. EIS allows dynamic analysis only under the assumption of a linear response to the excitation, therefore nonlinear electrochemcial and physical processes in the battery are simplified. NFRA extends dynamic analysis to the nonlinear domain. Additionally to the linear response, higher harmonic voltage responses are analyzed in the frequency domain.

The PhD student should advance our NRFA measurement procedure experimentally. For this purpose, optimal measurements conditions must be determined and measurement results must be characterized with respect to common metrological issues like traceability, reproducibility and measurement uncertainty, etc. Special focus must be placed on identifying and considering artifacts in the metrological assessment that occur due to measurement signal conditioning of the device. Such a conditioning is needed to optimize the design of an instrument for processing NFRA on batteries. Development of a deep understanding of the measurement technique under metrological aspects is essential to complete the task.

Applicants should have a master or comparable degree in physics, engineering or electrical technology and basic experience in laboratory work.

Further information:
Prof. Dr. Ulrike Krewer
Institute of Energy and Process Systems Engineering
TU Braunschweig
u [dot] krewer [at] tu-braunschweig [dot] de

TU Braunschweig