1. Introduction to Lithium Ion Battery

1.1 iState-of-Charge (SOC)

Imeko yentlawulo inokuchazwa njengemeko yamandla ombane akhoyo ebhetrini, adla ngokuchazwa njengepesenti. Ngenxa yokuba amandla ombane akhoyo ahluka ngentlawulo kunye nokukhutshwa kwangoku, ubushushu, kunye neziganeko zokuguga, inkcazo yesimo somrhumo ikwahlulwe ibe ziindidi ezimbini: i-Absolute State-Of-Charge (ASOC) kunye neRelative State-of-Charge (iRelative State). -Okuhlawuliswa iASOC) iState-of-Charge; RSOC). Ngokuqhelekileyo umgangatho ohambelanayo wokuhlawula ngu-0% -100%, ngelixa ibhetri i-100% xa ihlanjwe ngokupheleleyo kunye ne-0% xa ikhutshwe ngokupheleleyo. Imo yentlawulo epheleleyo lixabiso lereferensi elibalwe ngokwexabiso lesakhono esimisiweyo esiyilelweyo xa ibhetri yenziwe. Imeko yokuhlawula ngokupheleleyo ibhetri entsha kraca etshajiswe ngokupheleleyo yi-100%; kwaye nokuba ibhetri yokuguga ihlawuliswe ngokupheleleyo, ayikwazi ukufikelela kwi-100% phantsi kweemeko ezahlukeneyo zokutshaja kunye nokukhupha.

Lo mzobo ungezantsi ubonisa ubudlelwane phakathi kwamandla ombane kunye nomthamo webhetri kumazinga ahlukeneyo okukhutshwa. Okukhona isantya sokukhupha siphezulu, kokukhona sisezantsi umthamo webhetri. Xa ubushushu buphantsi, umthamo webhetri nawo uya kuncipha.

Umzobo 1.

Ubudlelwane phakathi kombane kunye nomthamo kumazinga ahlukeneyo okukhutshwa kunye namaqondo obushushu

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 Ihlawuliswa ngokupheleleyo

Xa umahluko phakathi kombane webhetri kunye nowona mbane uphezulu wokutshaja ungaphantsi kwe-100mV, kwaye ukutshaja kwangoku kuhla ukuya kwi-C/10, ibhetri inokuthathwa njengetyala ngokupheleleyo. Iimpawu zebhetri zihlukile, kwaye iimeko zokutshaja ngokupheleleyo zikwahluke.

Lo mzobo ungezantsi ubonisa ijiko eliqhelekileyo lokutshaja ibhetri ye-lithium. Xa i-voltage yebhetri ilingana neyona ndlela iphakamileyo yokutshaja kwaye i-chargeing current ihla ukuya kwi-C / 10, ibhetri ithathwa njengento epheleleyo.

Umzobo 2. Ijiko lephawu lokutshaja ibhetri yeLithium

1.4 I-Voltage Mini yokukhupha

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 Ukukhutshwa ngokupheleleyo

Xa i-voltage yebhetri ingaphantsi okanye ilingana ne-voltage encinci yokukhupha, ingabizwa ngokuba yi-dicharge epheleleyo.

1.6 Intlawulo kunye nexabiso lokukhupha (i-C-Rate)

Ixabiso lokukhupha intlawulo yimbonakaliso yentlawulo-ukukhutshwa ngoku ngokumalunga nomthamo webhetri. Umzekelo, ukuba i-1C isetyenziselwa ukukhupha iyure enye, ngokufanelekileyo, ibhetri iya kukhutshwa ngokupheleleyo. Iintlawulo ezahlukeneyo kunye nemilinganiselo yokukhupha iya kubangela umthamo osebenzayo ohlukeneyo. Ngokubanzi, ubukhulu bexabiso lokukhupha intlawulo, lincinci umthamo okhoyo.

1.7 Ubomi bomjikelo

Inani lemijikelo linani lamaxesha ibhetri ihlawulwe ngokupheleleyo kwaye ikhutshwe, enokuthi iqikelelwe kumthamo wokukhutshwa kunye nomthamo woyilo. Nanini na xa umthamo wokukhupha oqokelelweyo ulingana nomthamo woyilo, inani lemijikelo likanye. Ngokuqhelekileyo emva kwe-500 ye-charge-discharge cycles, umthamo webhetri egcwele ngokupheleleyo wehla nge-10% ~ 20%.

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

1.8 Ukuzikhupha

Ukuzikhupha ngokwazo zonke iibhetri kuyanda njengoko ubushushu bunyuka. Ukuzikhupha ngokusisiseko akuyiyo impazamo yokuvelisa, kodwa iimpawu zebhetri ngokwayo. Nangona kunjalo, ukuphathwa ngendlela engafanelekanga kwinkqubo yokuvelisa kunokubangela ukwanda kokuzikhupha. Ngokubanzi, izinga lokuzikhupha liphinda kabini kwi-10 ° C yokwanda kobushushu bebhetri. Ukuzikhupha ngenyanga kwiibhetri ze-lithium-ion malunga ne-1 ~ 2%, ngelixa ukukhutshwa kwenyanga nganye kwiibhetri ezisekelwe kwi-nickel yi-10-15%.

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

2. Intshayelelo yeBattery Fuel Gauge

2.1 Intshayelelo kwiFuel 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 yamandla ombane wesekethe

Imitha yombane usebenzisa indlela ye-voltage yesiphaluka evulekileyo kulula ukuyiphumeza, kwaye inokufumaneka ngokujonga phezulu kwetafile ehambelana nemeko yokuhlawula i-voltage yesiphaluka evulekileyo. Imeko yengqikelelo yombane wesekethe evulekileyo ngumbane weterminal yebhetri xa ibhetri iphumla malunga nemizuzu engama-30.

Ngaphantsi komthwalo owahlukileyo, ubushushu, kunye nokuguga kwebhetri, ijika lombane webhetri liya kwahluka. Ngoko ke, i-voltmeter evulekileyo evulekileyo yesiphaluka ayikwazi ukumela ngokupheleleyo imeko yentlawulo; imeko yentlawulo ayinakuqikelelwa ngokujonga phezulu kwetafile yodwa. Ngamanye amazwi, ukuba imeko yentlawulo iqikelelwa kuphela ngokujonga phezulu kwetafile, impazamo iya kuba nkulu kakhulu.

Lo mzobo ulandelayo ubonisa ukuba i-voltage yebhetri efanayo iphantsi kwentlawulo kunye nokukhutshwa, kwaye imeko yentlawulo efunyenwe yindlela yombane wesiphaluka evulekileyo ihluke kakhulu.

Umzobo 5. Umbane webhetri phantsi kokutshaja kunye nokukhutshwa

Umfanekiso ongezantsi ubonisa ukuba imeko yentlawulo iyahluka kakhulu phantsi kwemithwalo eyahlukeneyo ngexesha lokukhutshwa. Ke ngokusisiseko, indlela yombane wesekethe evulekileyo ifanelekile kuphela kwiinkqubo ezineemfuno ezisezantsi zokuchaneka kobume bentlawulo, njengokusetyenziswa kweebhetri ze-lead-acid okanye umbane ongenakuphazamiseka kwiimoto.

Umzobo 6. Ibhetri yebhetri phantsi kwemithwalo eyahlukeneyo ngexesha lokukhutshwa

2.3 Indlela yokulinganisa iCoulomb

Umgaqo wokusebenza wendlela yokulinganisa i-coulomb kukudibanisa i-resistor yokufumanisa kwindlela yokutshaja / yokukhupha ibhetri. I-ADC ilinganisa i-voltage kwi-resistor yokufumanisa kwaye iyiguqule kwixabiso langoku lebhetri ehlawuliswayo okanye ekhutshweyo. Ikhawuntari yexesha langempela (RTC) ibonelela ngokudityaniswa kwexabiso langoku kunye nexesha, ukuze wazi ukuba zingaphi ii-coulombs ezihamba ngazo.

Umzobo 7. Indlela esisiseko yokusebenza yendlela yokulinganisa iCoulomb

Indlela yokulinganisa iCoulomb inokubala ngokuchanekileyo imeko yexesha langempela lokuhlawula ngexesha lokutshaja okanye ukukhupha. Ngokusebenzisa i-counter coulomb counter kunye ne-discharge coulomb counter, ingabala umthamo oseleyo (RM) kunye nomthamo ogcweleyo (FCC). Ngexesha elifanayo, umthamo oseleyo (RM) kunye nomthamo opheleleyo wentlawulo (i-FCC) ingasetyenziselwa ukubala imeko yentlawulo, oko kukuthi (SOC = RM / FCC). Ukongeza, inokuphinda iqikelele ixesha eliseleyo, njengokuphela kwamandla (TTE) kunye namandla apheleleyo (TTF).

Figure 8. Calculation formula of Coulomb measurement method

Kukho izinto ezimbini eziphambili ezibangela ukuphambuka ekuchanekeni kwendlela yokulinganisa iCoulomb. Eyokuqala kukuqokelela kweempazamo ze-offset kwingqiqo yangoku kunye nokulinganisa kwe-ADC. Nangona impazamo yokulinganisa ngetekhnoloji yangoku isencinci, ukuba akukho ndlela ilungileyo yokuyiphelisa, impazamo iya kwanda ngokuhamba kwexesha. Umzobo ongezantsi ubonisa ukuba kwizicelo eziphathekayo, ukuba akukho kulungiswa kwixesha elide, impazamo eqokelelweyo ayinamda.

Umzobo 9. Impazamo eyongezelekayo yendlela yokulinganisa iCoulomb

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.

Umzobo 10. Iimeko zokuphelisa impazamo eyongezelekayo yendlela yokulinganisa iCoulomb

Inqaku lesibini eliphambili elibangela ukutenxa kokuchaneka kwendlela yokulinganisa i-coulomb yimpazamo yokuchasa ngokupheleleyo (i-FCC), nto leyo engumahluko phakathi kwexabiso lomthamo woyilo lwebhetri kunye nexabiso lebhetri elipheleleyo. Umthamo wentlawulo epheleleyo (FCC) iya kuchaphazeleka bubushushu, ukuguga, umthwalo kunye nezinye izinto. Ngoko ke, indlela yokufunda kwakhona kunye nembuyekezo yomthamo opheleleyo wentlawulo ibaluleke kakhulu kwindlela yokulinganisa i-coulomb. Lo mfanekiso ulandelayo ubonisa imeko yempazamo yentlawulo xa umthamo opheleleyo wentlawulo uqikelelwa kakhulu kwaye ungaphantsi.

Umzobo 11. Umzila wephutha xa umthamo ogcweleyo wentlawulo uqikelelwe kwaye ungaphantsi

2.4 Igeyiji yamafutha ombane aguqukayo

I-voltage eguquguqukayo ye-algorithm ye-fuel gauge ingabala imeko yentlawulo yebhetri ye-lithium ngokusekelwe kuphela kumbane webhetri. Le ndlela kukuqikelela ukunyuka okanye ukuncipha kwemeko yentlawulo ngokusekelwe kumahluko phakathi kombane webhetri kunye nombane ovulekileyo wesekethe yebhetri. Ulwazi lombane oguquguqukayo lunokulinganisa ngokufanelekileyo ukuziphatha kwebhetri ye-lithium ukumisela imeko yentlawulo ye-SOC (%), kodwa le ndlela ayikwazi ukuqikelela ixabiso lebhetri umthamo (mAh).

Indlela yayo yokubala isekelwe kumahluko oguquguqukayo phakathi kombane webhetri kunye nombane wesiphaluka ovulekileyo, ngokusebenzisa i-algorithm ephindaphindayo ukubala ukunyuka okanye ukuncipha kwemo yentlawulo ukuqikelela imeko yentlawulo. Xa kuthelekiswa nesisombululo se-coulomb metering gauge ye-fuel gauge, i-voltage eguquguqukayo ye-algorithm ye-fuel gauge ayiyi kuqokelela iimpazamo ekuhambeni kwexesha nangoku. I-Coulomb metering gauges ye-fuel gauges idla ngokubangela uqikelelo olungachanekanga lwemeko yentlawulo ngenxa yeempazamo zangoku zokuziva kunye nokuzikhupha kwebhetri. Nangona impazamo yangoku yokuva incinci kakhulu, i-counter ye-coulomb iya kuqhubeka iqokelela impazamo, kwaye impazamo eqokelelweyo inokupheliswa kuphela xa ihlawuliswe ngokupheleleyo okanye ikhutshwe ngokupheleleyo.

I-voltage eguqukayo ye-algorithm ye-fuel gauge iqikelela imeko yentlawulo yebhetri kuphela ngolwazi lombane; kuba ayiqikelelwa ngolwazi lwangoku lwebhetri, ayiqokeleli iimpazamo. Ukuze kuphuculwe ukuchaneka kobume bentlawulo, i-algorithm ye-voltage eguquguqukayo idinga ukusebenzisa isixhobo sokwenyani, kwaye uhlengahlengise iiparitha ze-algorithm ephuculweyo ngokwekona yombane webhetri xa ihlawuliswa ngokupheleleyo kwaye ikhutshwe ngokupheleleyo.

Umzobo 12. Ukusebenza kwe-voltage eguqukayo ye-algorithm ye-fuel gauge kunye nokufumana ukulungiswa

Oku kulandelayo kukusebenza kwe-algorithm yombane oguqukayo phantsi kweemeko ezahlukeneyo zokukhutshwa. Ingabonwa kumzobo ukuba imeko yayo yokuhlawula inokuchaneka okulungileyo. Kungakhathaliseki ukuba iimeko zokukhutshwa kweC / 2, C / 4, C / 7 kunye neC / 10, imeko yonke yempazamo yentlawulo yale ndlela ingaphantsi kwe-3%.

Umzobo 13. Ukusebenza kwemeko yentlawulo ye-algorithm yombane oguqukayo phantsi kweemeko ezahlukeneyo zokukhutshwa.

Umzobo ongezantsi ubonisa ukusebenza kwemeko yokuhlawula xa ibhetri ihlawulwe emfutshane kwaye ikhutshwe ngokukhawuleza. Imeko yempazamo yentlawulo isencinci kakhulu, kwaye impazamo enkulu yi-3% kuphela.

Umzobo 14. Ukusebenza kwemeko yentlawulo ye-algorithm yombane oguquguqukayo xa ibhetri ihlawulwe emfutshane kwaye ikhutshwe emfutshane.

Xa kuthelekiswa nemeko apho i-Coulomb metering gauge ye-fuel gauge idla ngokubangela ukungachaneki kwimeko yentlawulo ngenxa yeempazamo zangoku zokuva kunye nokuzikhupha kwebhetri, i-algorithm ye-voltage eguquguqukayo ayiqokeleli iimpazamo ngexesha kunye nangoku, okuyinzuzo enkulu. Ngenxa yokuba akukho lwazi malunga nentlawulo / ukukhutshwa kwangoku, i-algorithm ye-voltage eguquguqukayo inokuchaneka kwexesha elifutshane kunye nexesha lokuphendula elicothayo. Ukongeza, ayinakuqikelela umthamo ogcweleyo wentlawulo. Nangona kunjalo, iqhuba kakuhle ngokuchaneka kwexesha elide, kuba i-voltage yebhetri ekugqibeleni iya kubonisa ngokuthe ngqo imeko yayo yokuhlawula.