1. Introduction to Lithium Ion Battery

1.1 Isimo Sokukhokhiswa (SOC)

Isimo sokushaja singachazwa njengesimo samandla kagesi atholakalayo ebhethrini, ngokuvamile evezwa njengephesenti. Ngenxa yokuthi amandla kagesi atholakalayo ayahluka ngokuya ngeshaje kanye nezimo zokuphuma, izinga lokushisa, nezimo zokuguga, incazelo yesimo sokushaja nayo ihlukaniswe yaba izinhlobo ezimbili: I-Absolute State-Of-Charge (ASOC) kanye Nesimo Sokukhokhisa Esihlobene (Isimo Esihlobene -Iyakhokhiswa; i-ASOC) Isimo Sokukhokhiswa; RSOC). Ngokuvamile izinga lokushajwa elihlobene liba ngu-0% -100%, kuyilapho ibhethri lingu-100% uma selishajwe ngokugcwele kanye no-0% uma selishajwe ngokugcwele. Isimo sokushajwa esiphelele yinani eliyireferensi elibalwa ngokwenani eliklanyelwe lomthamo ongashintshi lapho ibhethri lakhiwe. Isimo sokushajwa esiphelele sebhethri elisha sha eshaji ngokugcwele ngu-100%; futhi noma ibhethri eliguga lishajwe ngokugcwele, alikwazi ukufinyelela ku-100% ngaphansi kwezimo ezihlukene zokushaja nokukhipha.

Isibalo esingezansi sibonisa ubudlelwano phakathi kwamandla kagesi namandla ebhethri ngamanani ahlukene okukhipha. Uma izinga lokuphuma liphakeme, umthamo webhethri uyancipha. Uma izinga lokushisa liphansi, umthamo webhethri nawo uzokwehla.

Umfanekiso we-1.

Ubudlelwano phakathi kwe-voltage namandla ngamazinga ahlukene okukhipha kanye namazinga okushisa

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 Ishajwe Ngokugcwele

Uma umehluko phakathi kwevoltheji yebhethri kanye nevoltheji yokushaja ephakeme kakhulu ingaphansi kuka-100mV, futhi ukushaja kwamanje kwehlela ku-C/10, ibhethri ingathathwa njengeshajwe ngokugcwele. Izici zebhethri zihlukile, nezimo zokushajwa ngokugcwele nazo zihlukile.

Isibalo esingezansi sibonisa ijika lesici sokushaja ibhethri le-lithium. Uma i-voltage yebhethri ilingana ne-voltage yokushaja ephakeme kakhulu futhi ukushaja kwamanje kwehlela ku-C/10, ibhethri libhekwa njengeshajwe ngokugcwele.

Umfanekiso 2. Ijika lesici sokushaja ibhethri le-lithium

1.4 I-Voltage Encane Yokukhipha

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 Ukukhipha ngokuphelele

Uma i-voltage yebhethri ingaphansi noma ilingana ne-voltage encane yokukhipha, ingabizwa ngokuthi ukukhishwa okuphelele.

1.6 Izinga lokushaja nokukhipha (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 Impilo yomjikelezo

Inombolo yemijikelezo inombolo yezikhathi lapho ibhethri lishajwe ngokuphelele futhi lishajwa, elingalinganiselwa kumthamo wangempela wokukhipha kanye nomthamo wokuklama. Noma kunini lapho umthamo wokukhipha oqoqiwe ulingana nomthamo wokuklama, inani lemijikelezo likanye. Ngokuvamile ngemva kwemijikelezo engu-500 yokushajwa, amandla ebhethri egcwele ehla ngo-10% ~ 20%.

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

1.8 Ukuzikhipha

Ukuzikhipha ngokwawo kwawo wonke amabhethri kuyenyuka njengoba izinga lokushisa likhuphuka. Ukuzikhipha ngokwakho empeleni akulona iphutha lokukhiqiza, kodwa izici zebhethri ngokwayo. Kodwa-ke, ukuphatha okungalungile ohlelweni lokukhiqiza nakho kungabangela ukwanda kokuzikhulula. Ngokuvamile, izinga lokuzikhipha ngokwakho liphindeka kabili kukho konke ukukhuphuka okungu-10°C kwezinga lokushisa lebhethri. Ukuzikhipha kwanyanga zonke kwamabhethri e-lithium-ion cishe ku-1~2%, kuyilapho ukuzikhipha ngokwakho kwanyanga zonke kwamabhethri asuselwa ku-nickel ahlukahlukene kungu-10-15%.

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

2. Isingeniso seBattery 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 Vula indlela ye-voltage yesekethe

Imitha kagesi esebenzisa indlela ye-voltage yesifunda evulekile kulula ukuyisebenzisa, futhi ingatholakala ngokubheka phezulu kwetafula elihambisana nesimo sokushaja se-voltage yesekethe evulekile. Isimo sokucatshangelwa se-voltage yesekethe evulekile i-voltage yetheminali yebhethri lapho ibhethri liphumula cishe imizuzu engama-30.

Ngaphansi komthwalo ohlukile, izinga lokushisa, nokuguga kwebhethri, ijika le-voltage yebhethri izohluka. Ngakho-ke, i-voltmeter engaguquki yesifunda evulekile ayikwazi ukumela ngokugcwele isimo sokushaja; isimo senkokhelo asinakulinganiswa ngokubheka phezulu kwetafula kuphela. Ngamanye amazwi, uma isimo senkokhelo silinganiselwa kuphela ngokubheka phezulu kwetafula, iphutha lizoba likhulu kakhulu.

Isibalo esilandelayo sibonisa ukuthi i-voltage yebhethri efanayo iyakhokhiswa futhi iyakhishwa, futhi isimo sokushaja esitholwa indlela ye-voltage yesifunda evulekile sihluke kakhulu.

Umfanekiso 5. I-voltage yebhethri ngaphansi kokushajwa nokushajwa

Isibalo esingezansi sibonisa ukuthi isimo sokukhokhisa sihluka kakhulu ngaphansi kwemithwalo ehlukene ngesikhathi sokukhishwa. Ngakho-ke, ngokuyisisekelo, indlela ye-voltage yesekethe evulekile ifaneleka kuphela kumasistimu anezidingo eziphansi zokunemba kwesimo sokushaja, njengokusetshenziswa kwamabhethri e-lead-acid noma amandla kagesi angaphazamiseki ezimotweni.

Umfanekiso 6. I-voltage yebhethri ngaphansi kwemithwalo ehlukene ngesikhathi sokukhipha

2.3 Indlela yokulinganisa ye-Coulomb

Umgomo wokusebenza wendlela yokulinganisa i-coulomb ukuxhuma isivimbeli esitholwayo endleleni yokushaja/yokukhipha ibhethri. I-ADC ikala i-voltage ku-resistor yokuthola futhi iyiguqule ibe inani lamanje lebhethri elishajwayo noma elilahlwayo. Ikhawunta yesikhathi sangempela (RTC) ihlinzeka ngokuhlanganiswa kwevelu yamanje nesikhathi, ukuze kwaziwe ukuthi mangaki ama-coulombs agelezayo.

Umfanekiso 7. Indlela eyisisekelo yokusebenza yendlela yokulinganisa ye-Coulomb

Indlela yokulinganisa ye-Coulomb ingabala ngokunembile isimo sezindleko zesikhathi sangempela phakathi nokushaja noma ukushajwa. Ngekhawunta yokushaja ye-coulomb kanye nekhawunta ye-coulomb yokukhipha, ingakwazi ukubala umthamo osele (RM) nomthamo wokushaja ogcwele (FCC). Ngesikhathi esifanayo, umthamo osele (RM) kanye nomthamo wokushaja ogcwele (FCC) nawo ungasetshenziswa ukubala isimo sokushaja, okungukuthi (SOC = RM / FCC). Ngaphezu kwalokho, ingakwazi futhi ukulinganisa isikhathi esisele, njengokuphelelwa amandla (TTE) namandla aphelele (TTF).

Figure 8. Calculation formula of Coulomb measurement method

Kunezici ezimbili eziyinhloko ezidala ukuchezuka ekunembeni kwendlela yokulinganisa ye-Coulomb. Esokuqala ukuqoqwa kwamaphutha e-offset ekuzweni kwamanje kanye nesilinganiso se-ADC. Nakuba iphutha lokulinganisa ngobuchwepheshe bamanje lisencane, uma ingekho indlela enhle yokuliqeda, iphutha lizokhula ngokuhamba kwesikhathi. Isibalo esingezansi sibonisa ukuthi ezinhlelweni zokusebenza, uma kungekho ukulungiswa ngesikhathi, iphutha eliqoqiwe alinamkhawulo.

Umfanekiso 9. Iphutha elikhulayo lendlela yokulinganisa ye-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.

Umfanekiso 10. Imibandela yokuqeda iphutha elinqwabelene lendlela yokulinganisa ye-Coulomb

Isici sesibili esikhulu esibangela ukuchezuka kokunemba kwendlela yokulinganisa i-coulomb iphutha lomthamo wokushaja ogcwele (FCC), okuwumehluko phakathi kwevelu yomthamo wokuklama ibhethri kanye nomthamo wangempela wokushajwa ogcwele webhethri. Umthamo wokushaja ogcwele (i-FCC) uzothintwa izinga lokushisa, ukuguga, umthwalo nezinye izici. Ngakho-ke, indlela yokufunda kabusha kanye nesinxephezelo yomthamo wokushaja ogcwele ibaluleke kakhulu endleleni yokulinganisa i-coulomb. Isibalo esilandelayo sibonisa isenzeko sephutha lesimo sokushaja lapho umthamo ogcwele wokushaja ulinganiselwa ngokweqile futhi ulinganiswa kancane.

Umfanekiso 11. Ithrendi yephutha lapho umthamo wokushaja ogcwele ulinganiswa ngokweqile futhi ulinganiswa kancane

2.4 I-Dynamic voltage algorithm fuel gauge

I-dynamic voltage algorithm fuel gauge ingabala isimo sokushajwa kwebhethri ye-lithium ngokusekelwe kuvolthi yebhethri kuphela. Le ndlela iwukulinganisa ukunyuka noma ukwehla kwesimo sokushaja ngokusekelwe kumehluko phakathi kwevoltheji yebhethri kanye ne-voltage yesekethe evulekile yebhethri. Ulwazi lwe-voltage eguqukayo lungalingisa ngempumelelo ukuziphatha kwebhethri le-lithium ukuze kutholwe isimo sokushajwa kwe-SOC (%), kodwa le ndlela ayikwazi ukulinganisa inani lomthamo webhethri (mAh).

Indlela yayo yokubala isekelwe kumehluko oguqukayo phakathi kwevoltheji yebhethri nevolthi yesekethe evulekile, ngokusebenzisa i-algorithm ephindaphindayo ukubala ukunyuka ngakunye noma ukwehla kwesimo sokushaja ukuze ulinganisele isimo sokushaja. Uma kuqhathaniswa nesixazululo se-coulomb metering gauge, i-dynamic voltage algorithm fuel gauge ngeke iqongelele amaphutha ngokuhamba kwesikhathi namanje. Amageji kaphethiloli emitha ye-Coulomb ngokuvamile abangela ukulinganiswa okungalungile kwesimo sokushaja ngenxa yamaphutha amanje ezinzwa kanye nokuzikhipha kwebhethri. Ngisho noma iphutha lamanje lenzwa lilincane kakhulu, ikhawunta ye-coulomb izoqhubeka nokuqongelela iphutha, futhi iphutha eliqoqiwe lingasuswa kuphela uma lishajwe ngokugcwele noma selikhishwe ngokuphelele.

I-dynamic voltage algorithm fuel gauge ilinganisela isimo sokushajwa kwebhethri kuphela ngolwazi lwe-voltage; ngoba ayilinganiswa ngolwazi lwamanje lwebhethri, ayiqoqi amaphutha. Ukuze kuthuthukiswe ukunemba kwesimo sokushaja, i-algorithm ye-voltage eguquguqukayo idinga ukusebenzisa idivayisi yangempela, futhi ilungise amapharamitha we-algorithm elungiselelwe ngokuya ngejika langempela le-voltage yebhethri uma ishajwe ngokugcwele futhi ikhishwa ngokuphelele.

Umfanekiso 12. Ukusebenza kwe-dynamic gauge ye-algorithm ye-fuel gauge kanye nokwenza ngcono

Okulandelayo ukusebenza kwe-algorithm ye-voltage eguquguqukayo ngaphansi kwezimo ezihlukene zesilinganiso sokukhipha. Kungabonakala emfanekisweni ukuthi isimo sayo sokukhokha sinokunemba okuhle. Kungakhathaliseki izimo zokukhishwa kwe-C/2, C/4, C/7 kanye ne-C/10, iphutha eliphelele lesimo sokushaja lale ndlela lingaphansi kuka-3%.

Umfanekiso 13. Ukusebenza kwesimo sokushaja se-algorithm ye-voltage eguquguqukayo ngaphansi kwezimo ezihlukene zesilinganiso sokukhipha

Isibalo esingezansi sibonisa ukusebenza kwesimo sokushajwa lapho ibhethri ishajwe isikhashana futhi ishajwa kafushane. Iphutha lesimo sokushaja lisencane kakhulu, futhi iphutha elikhulu liyi-3% kuphela.

Umfanekiso 14. Ukusebenza kwesimo sokushajwa kwe-algorithm ye-voltage eguquguqukayo lapho ibhethri ishajwa isikhashana futhi ishajwa isikhashana.

Uma kuqhathaniswa nesimo lapho i-Coulomb metering gauge ye-fuel gauge ngokuvamile ibangela isimo sokushaja esingalungile ngenxa yamaphutha amanje ezinzwa kanye nokuzikhipha kwebhethri, i-algorithm ye-voltage eguquguqukayo ayiqoqi amaphutha ngokuhamba kwesikhathi namanje, okuyinzuzo enkulu. Ngenxa yokuthi alukho ulwazi mayelana nokushaja/ukukhishwa kwamanje, i-algorithm ye-voltage eguquguqukayo inokunemba okumpofu kwesikhashana esifushane kanye nesikhathi sokuphendula esinensayo. Ngaphezu kwalokho, ayikwazi ukulinganisa umthamo wokushaja ogcwele. Kodwa-ke, yenza kahle ngokunemba kwesikhathi eside, ngoba i-voltage yebhethri izogcina ikhombisa ngokuqondile isimo sayo sokushaja.