1. Introduction to Lithium Ion Battery

1.1 Boemo ba Tefiso (SOC)

Boemo ba tefiso bo ka hlalosoa e le boemo ba matla a motlakase a teng ka har’a betri, hangata e hlahisoang e le peresente. Hobane matla a teng a motlakase a fapana ho ea ka tefiso le ts’ebetso ea hona joale, mocheso le botsofali, tlhaloso ea boemo ba tefiso e boetse e arotsoe ka mefuta e ‘meli: Absolute State-Of-Charge (ASOC) le Relative State-of-Charge (Relative State-of-Charge). -Oa Tefiso; ASOC) Boemo-baa-Tlaelo; RSOC). Ka tloaelo boemo bo lekanyelitsoeng ba tefiso ke 0% -100%, ha betri e le 100% ha e tjhajiloe ka botlalo le 0% ha e hlakotsoe ka botlalo. Boemo bo felletseng ba tefiso ke boleng ba referense bo baloang ho latela boleng bo hlophisitsoeng bo tsitsitseng ha betri e etsoa. Boemo bo felletseng ba tefiso ea betri e ncha e tjhakiloeng ka botlalo ke 100%; ‘me le haeba betri ea botsofali e lefshoa ka botlalo, e ke ke ea fihla 100% tlas’a maemo a fapaneng a ho tjhaja le a ho lahla.

Palo e ka tlase e bonts’a kamano lipakeng tsa voltage le matla a betri ka litekanyetso tse fapaneng tsa ho tsoa. Ha sekhahla sa ho tsoa se phahame, matla a betri a tlase. Ha mocheso o le tlase, matla a betri le ona a tla fokotseha.

Setšoantšo sa 1.

Kamano e teng lipakeng tsa voltage le matla ka litekanyetso tse fapaneng tsa ho tsoa le mocheso

1.2 Max Charging Voltage

The maximum charging voltage is related to the chemical composition and characteristics of the battery. The charging voltage of lithium battery is usually 4.2V and 4.35V, and the voltage value will be different if the cathode and anode materials are different.

1.3 Ho Lefisoa ka Botlalo

Ha phapang pakeng tsa matla a betri le matla a phahameng ka ho fetisisa a ho tjhaja a le ka tlase ho 100mV, mme hona joale ho tjhaja ho theohela ho C/10, betri e ka nkuwa e tjhajilwe ka botlalo. Litšobotsi tsa betri li fapane, ‘me maemo a tjhaja ka botlalo le ona a fapane.

Setšoantšo se ka tlase se bonts’a mokhoa o tloaelehileng oa ho tjhaja betri ea lithium. Ha matla a betri a lekana le motlakase o phahameng ka ho fetisisa oa ho tjhaja ‘me hona joale ho tjhaja ho theohela ho C/10, betri e nkoa e qosoa ka botlalo.

Setšoantšo sa 2. Mokokotlo oa sebopeho sa betri ea lithium

1.4 Motlakase o Monyane oa ho Discharging

The minimum discharge voltage can be defined by the cut-off discharge voltage, which is usually the voltage when the state of charge is 0%. This voltage value is not a fixed value, but changes with load, temperature, aging degree, or other factors.

1.5 Ho tsoa ka botlalo

Ha matla a betri a le ka tlase ho kapa a lekana le bonyane ba motlakase oa ho tsoa, ​​​​e ka bitsoa ho tsoa ka ho feletseng.

1.6 Sekhahla sa tefiso le ho tsoa (C-Rate)

The charge-discharge rate is an expression of the charge-discharge current relative to the battery capacity. For example, if 1C is used to discharge for one hour, ideally, the battery will be completely discharged. Different charge and discharge rates will result in different usable capacity. Generally, the greater the charge-discharge rate, the smaller the available capacity.

1.7 Bophelo ba potoloho

Palo ea lipotoloho ke palo ea makhetlo ao betri e tjhaetsoeng ka ho felletseng le ho tsoa ho eona, e ka hakanyetsoang ho tsoa ho matla a ho tsoa le a moralo. Nako le nako ha matla a ho ntša a bokelletsoeng a lekana le bokhoni ba moralo, palo ea lipotoloho e hang. Hangata ka mor’a lipotoloho tse 500 tsa ho ntša litefello, matla a betri e tjhatsitsoeng ka botlalo a theoha ka 10% ~ 20%.

Figure 3. The relationship between the number of cycles and battery capacity

1.8 Ho Ipholla

Ho itšehla thajana ha libeteri tsohle ho eketseha ha mocheso o ntse o phahama. Ho itšehla thajana ha e le hantle ha se bofokoli ba tlhahiso, empa litšobotsi tsa betri ka boeona. Leha ho le joalo, ho se sebetse ka mokhoa o sa nepahalang ha mokhoa oa tlhahiso ho ka boela ha baka keketseho ea ho itšehla thajana. Ka kakaretso, sekhahla sa ho itšehla thajana se imena habeli bakeng sa keketseho e ‘ngoe le e ‘ngoe ea 10°C ea mocheso oa betri. Khoeli ea khoeli le khoeli ea ho itšeha ha libeteri tsa lithium-ion ke hoo e ka bang 1 ~ 2%, ha khoeli le khoeli ea ho itšeha ha libeteri tse fapaneng tse thehiloeng ho nickel ke 10-15%.

Figure 4. The performance of the self-discharge rate of lithium batteries at different temperatures

2. Kenyelletso ea Battery Fuel Gauge

2.1 Introduction to Fuel Gauge Function

Battery management can be regarded as part of power management. In battery management, the fuel gauge is responsible for estimating battery capacity. Its basic function is to monitor the voltage, charge/discharge current and battery temperature, and estimate the battery state of charge (SOC) and the battery’s full charge capacity (FCC). There are two typical methods for estimating the state of charge of a battery: the open circuit voltage method (OCV) and the coulometric method. Another method is the dynamic voltage algorithm designed by RICHTEK.

2.2 Mokhoa oa ho bula motlakase oa potoloho

Methara ea motlakase e sebelisang mokhoa o bulehileng oa motlakase oa potoloho e bonolo ho e sebelisa, ‘me e ka fumanoa ka ho sheba tafoleng e tsamaellanang le boemo ba tefiso ea motlakase o bulehileng oa potoloho. Boemo ba boikaketsi ba motlakase oa potoloho e bulehileng ke motlakase oa betri ha betri e phomola metsotso e ka bang 30.

Tlas’a mojaro o fapaneng, mocheso, le botsofali ba betri, lebelo la voltage ea betri le tla fapana. Ka hona, voltmeter e tsitsitseng e bulehileng ea potoloho e ke ke ea emela ka botlalo boemo ba tefiso; boemo ba tefiso bo ke ke ba hakanyetsoa ka ho sheba tafoleng feela. Ka mantsoe a mang, haeba boemo ba tefiso bo hakanngoa feela ka ho sheba tafoleng, phoso e tla ba khōlō haholo.

Setšoantšo se latelang se bontša hore motlakase o tšoanang oa betri o tlas’a tefiso le ho tsoa, ​​’me boemo ba tefiso bo fumanoang ke mokhoa o bulehileng oa motlakase oa potoloho bo fapane haholo.

Setšoantšo sa 5. Matla a betri tlas’a ho tjhaja le ho ntša

Setšoantšo se ka tlase se bontša hore boemo ba tefiso bo fapana haholo tlas’a meroalo e fapaneng nakong ea ho tsoa. Ha e le hantle, mokhoa o bulehileng oa motlakase oa potoloho o loketse feela lits’ebetso tse nang le litlhoko tse tlase bakeng sa ho nepahala ha boemo ba tefiso, joalo ka ts’ebeliso ea libeteri tsa lead-acid kapa lisebelisoa tsa motlakase tse ke keng tsa senyeha likoloing.

Setšoantšo sa 6. Matla a betri tlas’a meroalo e fapaneng nakong ea ho tsoa

2.3 Mokhoa oa ho lekanya Coulomb

Molao-motheo oa ts’ebetso ea mokhoa oa ho lekanya coulomb ke ho hokahanya mochine o thibelang ho lemoha tseleng ea ho tjhaja / ho lahla ea betri. ADC e lekanya matla a motlakase holim’a sesebelisoa sa ho lemoha ebe e e fetola boleng ba hona joale ba betri e tjhajoang kapa e lokolloang. The real-time counter (RTC) e fana ka kopanyo ea boleng ba hona joale le nako, e le ho tseba hore na ke li-coulombs tse kae tse phallang.

Setšoantšo sa 7. Mokhoa oa motheo oa ho sebetsa oa mokhoa oa ho lekanya Coulomb

Mokhoa oa ho lekanya Coulomb o ka lekanya ka nepo boemo ba tefiso ea nako ea nnete nakong ea ho tjhaja kapa ho tjhaja. Ka counter counter coulomb le discharge coulomb counter, e ka bala matla a setseng (RM) le tekanyo e feletseng ea tefiso (FCC). Ka nako e ts’oanang, matla a setseng (RM) le tekanyo e feletseng ea tefiso (FCC) e ka boela ea sebelisoa ho bala boemo ba tefiso, ke hore (SOC = RM / FCC). Ho phaella moo, e ka boela ea hakanya nako e setseng, e kang ho felloa ke matla (TTE) le matla a feletseng (TTF).

Figure 8. Calculation formula of Coulomb measurement method

Ho na le lintlha tse peli tse ka sehloohong tse bakang ho kheloha ho nepahala ha mokhoa oa ho lekanya Coulomb. Ea pele ke ho bokelloa ha liphoso tsa offset ho kutlo ea hajoale le tekanyo ea ADC. Le hoja phoso ea tekanyo le theknoloji ea morao-rao e ntse e le nyenyane, haeba ho se na mokhoa o motle oa ho e felisa, phoso e tla eketseha ka nako. Palo e ka tlase e bontša hore lits’ebetsong tse sebetsang, haeba ho se na tokiso nakong ea nako, phoso e bokelitsoeng ha e na moeli.

Setšoantšo sa 9. Phoso e akaretsang ea mokhoa oa ho lekanya Coulomb

In order to eliminate the accumulated error, there are three possible useable time points in normal battery operation: end of charge (EOC), end of discharge (EOD) and rest (Relax). When the charging end condition is reached, it means that the battery is fully charged and the state of charge (SOC) should be 100%. The discharge end condition means that the battery has been completely discharged and the state of charge (SOC) should be 0%; it can be an absolute voltage value or change with the load. When it reaches the resting state, the battery is neither charged nor discharged, and it remains in this state for a long time. If the user wants to use the rest state of the battery to correct the error of the coulomb measurement method, an open-circuit voltmeter must be used at this time. The figure below shows that the state of charge error can be corrected in the above state.

Setšoantšo sa 10. Maemo a ho felisa phoso e akaretsang ea mokhoa oa ho lekanya Coulomb

Ntho ea bobeli e kholo e bakang ho kheloha ho nepahala ha mokhoa oa ho lekanya coulomb ke phoso ea tekanyo e feletseng ea tefiso (FCC), e leng phapang pakeng tsa boleng ba matla a moralo oa betri le matla a ‘nete a tjhaja a feletseng a betri. Bokhoni bo felletseng ba tefiso (FCC) bo tla angoa ke mocheso, botsofali, mojaro le lintlha tse ling. Ka hona, mokhoa oa ho ithuta hape le oa matšeliso a matla a feletseng a tefiso ke oa bohlokoa haholo bakeng sa mokhoa oa ho lekanya coulomb. Palo e latelang e bonts’a ts’ebetso ea ts’ebetso ea phoso ea boemo ba tefiso ha tekanyo e felletseng ea tefiso e lekanyelitsoe ebile e sa lebelloa.

Setšoantšo sa 11. Tloaelo ea phoso ha tekanyo e feletseng ea tefiso e lekanyelitsoe ebile e sa lebelloa

2.4 Dynamic voltage algorithm fuel gauge

The dynamic voltage algorithm fuel gauge e ka lekanya boemo ba tefiso ea betri ea lithium e ipapisitse le matla a betri feela. Mokhoa ona ke ho hakanya keketseho kapa ho fokotseha ha boemo ba tefiso ho ipapisitse le phapang lipakeng tsa voltage ea betri le matla a bulehileng a betri. Lintlha tse matla tsa motlakase li ka etsisa boits’oaro ba betri ea lithium ho tseba boemo ba tefiso ea SOC (%), empa mokhoa ona o ke ke oa hakanya boleng ba betri (mAh).

Mokhoa oa eona oa ho bala o ipapisitse le phapang e matla lipakeng tsa motlakase oa betri le motlakase oa potoloho e bulehileng, ka ho sebelisa algorithm e pheta-phetoang ho bala keketseho kapa ho fokotseha ha boemo ba tefiso ho hakanya boemo ba tefiso. Ha ho bapisoa le tharollo ea coulomb metering gauge ea mafura, dynamic voltage algorithm fuel gauge e ke ke ea bokella liphoso ka nako le hona joale. Li-gauge tsa mafura tsa coulomb metering hangata li baka khakanyo e fosahetseng ea boemo ba tefiso ka lebaka la liphoso tsa hajoale tsa ho utloa le ho itšeha ha betri. Esita le haeba phoso ea hona joale ea ho utloa e le nyenyane haholo, k’hamphani ea coulomb e tla tsoela pele ho bokella phoso, ‘me phoso e bokelitsoeng e ka tlosoa feela ha e qosoa ka ho feletseng kapa e lokolloa ka ho feletseng.

The dynamic voltage algorithm fuel gauge e hakanya boemo ba tefiso ea betri feela ka tlhaiso-leseling ea motlakase; hobane ha e hakanyetsoe ke tlhahisoleseling ea hajoale ea betri, ha e bokelle liphoso. E le ho ntlafatsa ho nepahala ha boemo ba tefiso, algorithm ea dynamic voltage e hloka ho sebelisa sesebelisoa sa ‘nete, le ho lokisa liparamente tsa algorithm e ntlafalitsoeng ho ea ka sekhahla sa motlakase oa betri ha e tjhaja ka botlalo mme e tsoa ka botlalo.

Setšoantšo sa 12. Ts’ebetso ea dynamic voltage algorithm fuel gauge le ho fumana optimization

The following is the performance of the dynamic voltage algorithm under different discharge rate conditions. It can be seen from the figure that its state of charge has good accuracy. Regardless of the discharge conditions of C/2, C/4, C/7 and C/10, the overall state of charge error of this method is less than 3%.

Setšoantšo sa 13. Ts’ebetso ea boemo ba tefiso ea algorithm ea dynamic voltage tlas’a maemo a fapaneng a ho lahla.

Setšoantšo se ka tlase se bonts’a ts’ebetso ea boemo ba tefiso ha betri e le khutšoanyane ebile e le khutšoanyane. Phoso ea boemo ba tefiso e ntse e le nyane haholo, mme phoso e kholo ke 3% feela.

Setšoantšo sa 14. Ts’ebetso ea boemo ba tefiso ea algorithm ea dynamic voltage ha betri e le khutšoanyane ebile e le khutšoanyane.

Ha ho bapisoa le boemo boo Coulomb metering gauge ea mafura hangata e bakang boemo bo sa nepahalang ba tefiso ka lebaka la liphoso tsa hona joale tsa ho utloa le ho itšehla thajana ha betri, algorithm ea matla a matla ha e bokelle liphoso ka nako le hona joale, e leng molemo o moholo. Hobane ha ho na tlhahisoleseling mabapi le tefiso / ho lahla hona joale, algorithm ea matla a matla e na le ho nepahala ha nako e khuts’oane le nako ea ho arabela butle. Ho feta moo, e ke ke ea hakanya palo e felletseng ea tefiso. Leha ho le joalo, e sebetsa hantle mabapi le ho nepahala ha nako e telele, hobane motlakase oa betri o tla qetella o bonahatsa ka ho toba boemo ba eona ba tefiso.