Li-ion akude mahutavuse mõõtmise kaudsed meetodid
Laen...
Kuupäev
2017
Kättesaadav alates
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Li-ion akude mahutavus väheneb aja jooksul sõltumata sellest, kas nad on olnud kasutuses
või mitte. Järelikult on vaja hinnata aku mahutavust ka kasutamata või vähekasutatud
seadmetel. Integreeritud akudega seadmetel puudub kasutajal otsene ligipääs aku
klemmidele, mis ei lase aku mahutavuse mõõtmisel kasutada traditsioonilisi meetodeid.
Seetõttu tuleb kasutada aku mahutavuse hindamiseks väiksema täpsusega meetodeid, s.t.
mõõta aku laadimisel kulutatud energiat ja hinnata, kui suure osa sellest moodustab
kasulik, seadme poolt kasutatav akusse salvestatud energia.
Käesoleva töö eesmärgiks on kirjeldada kahte erinevat meetodit testseadmes oleva aku
mahutavuse mõõtmiseks, kasutades ainult testseadme laadimisprotsessi käigus mõõdetud
andmeid ning hinnata nende meetodite täpsust. Kasutades Li-ion akude
laadimisprotsesside ning testseadme laadimisenergia jagunemise uurimisel saadud
teadmisi määratleti kaks meetodit. Meetodid erinevad peamiselt kasutatud mõõteseadmete
poolest. Esimene meetod kasutab laadimisenergia mõõtmiseks mõõteseadet Agilent
34972A, mis ei ole tavakasutajale kättesaadav. Teine meetod kasutab akupanka, USBtoitega
koormavat seadet ja ajamõõtjat, mis on tavakasutajale kättesaadavad.
Testitavaks seadmeks valiti mobiiltelefon Sony Xperia V, mille akut sai telefonist
eraldada. See võimaldas testseadme aku mahutavust mõõta nii laadimisenergiat mõõtes
kui ka otse aku klemmidelt. Vastavalt kirjeldatud meetoditele viidi läbi kaks mõõtmist
ning kontrollmõõtmine, mille tulemuse abil hinnati teiste meetodite täpsust. Autor leidis,
et esimese meetodiga tehtud mõõtmine on piisavalt täpne, andmaks hinnangut aku
mahutavuse säilimisele, võrreldes esialgse mahutavusega. Teise meetodi puhul leidis
autor, et mõõtmistulemuse täpsus sõltub testseadme laadimisprotsessis kontrollmooduli
poolt tarbitud energia suhtest aku mahutavusse.
Edaspidistes uuringutes soovitab autor edasi arendada meetodit II, tehes katseid erinevate
seadmetega, et suurendada meetodi mõõtetulemuste usaldusväärsust.
Li-ion battery capacity decreases over time, regardless of whether they have been in use or not. Consequently, there is also a need to assess the capacity of unused or less used batteries. Devices with built-in batteries do not allow for direct access to the terminals of the battery, making traditional capacity measurement methods unusable. Therefore, less accurate indirect methods must be used to assess capacitance, i.e. to measure the energy used in charging the battery and assess how much if it is useful, usable energy. The aim of this thesis is to describe and evaluate the accuracy of two different methods of battery capacity measurement, using only the data gathered during the charging process. Two methods of measurement were formulated using knowledge derived from studying the charging processes and distribution of charging energy of Li-ion batteries. The methods differ primarily in terms of the measuring equipment used. The first method uses an Agilent34972a charging device, which is not available to the average user. The second method uses a battery bank, USB device and a stopper, which are available to the average user. A mobile phone with a removable battery was used as the test device, which allowed for both direct battery capacity measurement, using the terminals, and indirect measurement using the charging energy. In accordance with the formulated methods, two indirect measurements and a control measurement were carried out. The control measurement was used to assess the accuracy of the indirect measurements. The author found that the measurements made using the first method were sufficiently accurate to assess the capacity of the battery in relation to the nominal capacity. The author also concluded that the precision of Method 2 depends mostly on the ratio of energy used by the control module and the capacity of the battery. In later trials, the author wishes to further develop Method 2 by testing with various devices, in order to increase the measurement accuracy of the method.
Li-ion battery capacity decreases over time, regardless of whether they have been in use or not. Consequently, there is also a need to assess the capacity of unused or less used batteries. Devices with built-in batteries do not allow for direct access to the terminals of the battery, making traditional capacity measurement methods unusable. Therefore, less accurate indirect methods must be used to assess capacitance, i.e. to measure the energy used in charging the battery and assess how much if it is useful, usable energy. The aim of this thesis is to describe and evaluate the accuracy of two different methods of battery capacity measurement, using only the data gathered during the charging process. Two methods of measurement were formulated using knowledge derived from studying the charging processes and distribution of charging energy of Li-ion batteries. The methods differ primarily in terms of the measuring equipment used. The first method uses an Agilent34972a charging device, which is not available to the average user. The second method uses a battery bank, USB device and a stopper, which are available to the average user. A mobile phone with a removable battery was used as the test device, which allowed for both direct battery capacity measurement, using the terminals, and indirect measurement using the charging energy. In accordance with the formulated methods, two indirect measurements and a control measurement were carried out. The control measurement was used to assess the accuracy of the indirect measurements. The author found that the measurements made using the first method were sufficiently accurate to assess the capacity of the battery in relation to the nominal capacity. The author also concluded that the precision of Method 2 depends mostly on the ratio of energy used by the control module and the capacity of the battery. In later trials, the author wishes to further develop Method 2 by testing with various devices, in order to increase the measurement accuracy of the method.
Kirjeldus
Bakalaureusetöö
Tehnika ja tehnoloogia õppekaval
Märksõnad
bakalaureusetööd, nutitelefonid, akupangad