Modeliranje, eksperimentalna identifikacija te dizajn estimatora stanja i regulacijskih sustava punjenja za litij-titanat baterije

master's thesis

• Title (english): Modelling, experimental identification, state estimator and charging control systems design for lithium-titanate batteries
• Author: Karlo Kvaternik
• Mentor: Danijel Pavković (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2023-07-20, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Automation and Robotics

Abstract

Među mnogim punjivim litijevim baterijama, litij-titanat ćelije karakteriziraju najviša razina toplinske stabilnosti i radne sigurnosti, što ih čini posebno prikladnima za visoko zahtjevne primjene. Ovaj rad predstavlja identifikaciju, rezultate eksperimentalne karakterizacije ćelije litij-titanat baterije te dizajn CCCV sustava upravljanja punjenja baterije korištenjem strukture kaskadnog sustava upravljanja u kojem se stanje napunjenosti baterije kontrolira na takav način da se postigne potpuno napunjeno stanje u minimalnom vremenu, poštujući ograničenja napona baterije i struje punjenja. CCCV sustav je korišten kao usporedba za punjač temeljen na neizrazitoj logici koji imitira pulsno punjenje. Identifikacija modela baterijskih ćelija provedena je u tri faze: (i) snimanje napona otvorenog kruga u odnosu na karakteristike stanja napunjenosti pomoću punjenja slabom strujom isprekidanog s intervalima rekuperacije napona baterije u cijelom rasponu baterije napona, (ii) određivanje efektivnog kapaciteta punjenja baterije i (iii) identifikaciju serijskog otpora baterijskih ćelija i polarizacijskog otpora i vremenske konstante kašnjenja za različite vrijednosti struje punjenja korištenjem rekurzivne procjene parametra na temelju testnog signala pseudoslučajnog binarnog niza. Povratna informacija o stanju napunjenosti osigurava se korištenjem proširenog Kalmanovog filtra koji uključuje realistični nelinearni Theveninov model ekvivalentnog kruga baterijske ćelije. Učinkovitost predloženog estimatora i neizrazitog punjača provjerena je pomoću simulacija.

Abstract (english)

Among the many rechargeable lithium batteries, lithium-titanante cells are characterized by highest thermal stability and operational safety levels, which makes them particularly well suited for highly-demanding applications. This paper presents the results of experimental characterization of a lithium-titanate battery cell and design of a CCCV battery charging control system using a cascade control system arrangement wherein the battery state-of-charge is controlled in such a way so as to reach the fully charged state in a minimum time, while honoring the battery cell voltage and charging current constraints. CCCV system is used as a comparison for fuzzy charging control system which imitates pulse charging. Battery cell model identification has been carried out in three stages: (i) recording of the open-circuit voltage vs. state-of-charge characteristic by means of low-current charging interspersed with battery voltage recuperation intervals over the full-range of battery voltages, (ii) determination of the effective battery charge capacity, and (iii) identification of battery cell series resistance and polarization resistance and lag time constant for different charging current values using recursive parameter estimation based on pseudo-random binary sequence test signal. The state-of-charge feedback is provided by using an extended Kalman filter which incorporates the realistic nonlinear Thevenin model of the battery cell equivalent circuit. The effectiveness of the proposed estimator and fuzzy charger is verified by means of simulations.

• Keywords: Litij-titanatna baterijska ćelija; Model ekvivalentnog kruga; Eksperimentalna identifikacija; Procjena stanja; Prošireni Kalmanov filter; CCCV metoda punjenja; Punjenje temeljeno na neizrazitom upravljanju.
• Keywords (english): Lithium-Titanate Battery Cell; Equivalent Circuit Model; Experimental Identification; State-of-Charge Estimation; Extended Kalman Filter; CCCV Charging; Fuzzy Charging Control
• Language: croatian
• URN:NBN: urn:nbn:hr:235:803099
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-07-06 14:04:12