1. Introduction to Lithium Ion Battery

1.1 State-Of-Chaw (SOC)

Lub xeev tus nqi tuaj yeem txhais tau tias yog lub xeev ntawm cov hluav taws xob muaj hluav taws xob hauv lub roj teeb, feem ntau qhia tau tias yog feem pua. Vim hais tias cov hluav taws xob muaj hluav taws xob sib txawv nrog kev them nqi thiab tawm tam sim no, qhov kub thiab txias, thiab qhov tshwm sim ntawm kev laus, lub ntsiab lus ntawm lub xeev tus nqi kuj tau muab faib ua ob hom: Absolute State-Of-Charge (ASOC) thiab txheeb ze State-of-Charge (Relative State. -Of-Chaw; ASOC) State-Of-Chaw; RSOC). Feem ntau cov txheeb ze ntawm cov nqi them yog 0% -100%, thaum lub roj teeb yog 100% thaum them tag nrho thiab 0% thaum tso tawm tag nrho. Qhov tseeb ntawm tus nqi yog tus nqi siv xam raws li tus nqi tsim nyog ruaj khov thaum lub roj teeb tsim. Lub xeev tus nqi ntawm cov khoom lag luam tshiab uas them tag nrho yog 100%; thiab txawm tias lub roj teeb uas muaj hnub nyoog tau them tag nrho, nws tsis tuaj yeem ncav cuag 100% raws li kev them nqi sib txawv thiab kev tso tawm.

Daim duab hauv qab no qhia txog kev sib raug zoo ntawm qhov hluav taws xob thiab lub roj teeb muaj peev xwm ntawm cov nqi sib txawv. Qhov siab dua tus nqi tso tawm, lub roj teeb muaj peev xwm qis dua. Thaum qhov kub thiab txias qis, lub roj teeb muaj peev xwm kuj yuav txo.

Daim duab 1.

Kev sib raug zoo ntawm qhov hluav taws xob thiab qhov muaj peev xwm ntawm qhov sib txawv tawm thiab qhov kub thiab txias

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 Them tag nrho

Thaum qhov sib txawv ntawm lub roj teeb voltage thiab lub siab tshaj plaws them voltage tsawg dua 100mV, thiab cov nqi them tam sim no poob rau C / 10, lub roj teeb tuaj yeem suav tias yog them tag nrho. Cov yam ntxwv roj teeb txawv, thiab cov nqi them tag nrho kuj txawv.

Daim duab hauv qab no qhia tau hais tias ib txwm lithium roj teeb them tus yam ntxwv nkhaus. Thaum lub roj teeb hluav taws xob sib npaug rau qhov siab tshaj plaws them hluav taws xob thiab qhov them tam sim no poob rau C / 10, lub roj teeb tau txiav txim siab them tag nrho.

Daim duab 2. Lithium roj teeb them tus yam ntxwv nkhaus

1.4 Mini tso zis voltage

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 Tso tawm tag nrho

Thaum lub roj teeb voltage tsawg dua los yog sib npaug rau qhov tsawg kawg nkaus tawm qhov hluav taws xob, nws tuaj yeem raug hu ua tiav kev tawm.

1.6 Tus nqi them thiab tso tawm (C-Rate)

Tus nqi them-tso tawm yog ib qho kev qhia ntawm tus nqi-tso tawm tam sim no txheeb ze rau lub peev xwm roj teeb. Piv txwv li, yog tias 1C siv los tso tawm rau ib teev, qhov zoo tshaj plaws, lub roj teeb yuav raug tso tawm tag nrho. Cov nqi sib txawv thiab kev tso tawm yuav ua rau muaj peev xwm siv tau sib txawv. Feem ntau, qhov ntau dua tus nqi-tso tawm, qhov tsawg dua qhov muaj peev xwm.

1.7 Lub neej voj voog

Tus naj npawb ntawm cov voj voog yog tus naj npawb ntawm lub sijhawm uas lub roj teeb tau dhau los ua tiav kev them nyiaj thiab tawm, uas tuaj yeem kwv yees los ntawm lub peev xwm tso tawm tiag tiag thiab lub peev xwm tsim. Thaum twg qhov kev tso tawm muaj peev xwm sib npaug ntawm qhov tsim muaj peev xwm, tus naj npawb ntawm cov voj voog yog ib zaug. Feem ntau tom qab 500 lub sij hawm them-tso tawm, lub peev xwm ntawm lub roj teeb tag nrho poob los ntawm 10% ~ 20%.

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

1.8 Kev Tso Tawm Tus Kheej

Kev tso tawm tus kheej ntawm txhua lub roj teeb nce ntxiv thaum kub nce. Kev tso tawm tus kheej yog qhov pib tsis yog kev tsim khoom, tab sis cov yam ntxwv ntawm lub roj teeb nws tus kheej. Txawm li cas los xij, kev tuav tsis raug hauv cov txheej txheem tsim khoom kuj tuaj yeem ua rau muaj kev tawm ntawm tus kheej. Feem ntau, tus nqi tawm tus kheej ob npaug rau txhua 10 ° C nce hauv roj teeb kub. Lub hli nws tus kheej tawm ntawm lithium-ion roj teeb yog li 1 ~ 2%, thaum lub hli tus kheej tso tawm ntawm ntau yam nickel-based roj teeb yog 10-15%.

Daim duab 4. Kev ua haujlwm ntawm tus kheej tawm tus nqi ntawm cov roj teeb lithium ntawm qhov kub sib txawv

2. Taw qhia txog roj teeb roj ntsuas

2.1 Kev Taw Qhia Txog Roj Gauge Function

Kev tswj roj teeb tuaj yeem suav tias yog ib feem ntawm kev tswj fais fab. Hauv kev tswj roj teeb, lub ntsuas roj yog lub luag haujlwm rau kwv yees lub peev xwm roj teeb. Nws lub luag haujlwm tseem ceeb yog saib xyuas qhov hluav taws xob, them nqi / tawm tam sim no thiab roj teeb kub, thiab kwv yees lub roj teeb lub xeev ntawm kev them nqi (SOC) thiab lub roj teeb lub peev xwm (FCC). Muaj ob txoj hauv kev rau kev kwv yees lub xeev ntawm tus nqi ntawm lub roj teeb: qhib Circuit Court voltage txoj kev (OCV) thiab txoj kev coulometric. Lwm txoj kev yog dynamic voltage algorithm tsim los ntawm RICHTEK.

2.2 Qhib Circuit Court voltage txoj kev

Lub ntsuas hluav taws xob siv txoj kev qhib hluav taws xob hluav taws xob yog yooj yim dua rau kev siv, thiab nws tuaj yeem tau txais los ntawm kev saib lub rooj sib xws rau lub xeev tus nqi ntawm qhov qhib hluav taws xob hluav taws xob. Lub hypothetical mob ntawm qhov qhib Circuit Court voltage yog lub roj teeb davhlau ya nyob twg voltage thaum lub roj teeb so li 30 feeb.

Nyob rau hauv txawv load, kub, thiab roj teeb aging, lub roj teeb voltage nkhaus yuav txawv. Yog li ntawd, lub kaw lus qhib-circuit voltmeter tsis tuaj yeem sawv cev rau lub xeev tus nqi; lub xeev tsis tuaj yeem kwv yees los ntawm kev saib lub rooj ib leeg. Hauv lwm lo lus, yog tias lub xeev tus nqi kwv yees tsuas yog los ntawm kev saib lub rooj, qhov yuam kev yuav loj heev.

Cov duab hauv qab no qhia tau hais tias tib lub roj teeb hluav taws xob yog nyob rau hauv kev them nqi thiab tawm, thiab lub xeev cov nqi pom los ntawm txoj kev qhib hluav taws xob hluav taws xob sib txawv heev.

Daim duab 5. Lub roj teeb hluav taws xob hauv qab them thiab tawm

Daim duab hauv qab no qhia tau hais tias lub xeev ntawm tus nqi sib txawv heev nyob rau hauv txawv loads thaum tawm. Yog li qhov yooj yim, txoj kev qhib hluav taws xob hluav taws xob tsuas yog tsim rau cov tshuab uas tsis tshua muaj kev xav tau rau qhov tseeb ntawm lub xeev tus nqi, xws li kev siv cov roj ntsha lead-acid lossis cov khoom siv hluav taws xob tsis cuam tshuam hauv tsheb.

Daim duab 6. Roj teeb voltage nyob rau hauv txawv loads thaum tawm

2.3 Coulomb ntsuas txoj kev

Cov kev khiav hauj lwm hauv paus ntsiab lus ntawm cov coulomb ntsuas txoj kev yog mus cuag ib tug kom paub tias resistor nyob rau them / ntxub txoj kev ntawm lub roj teeb. ADC ntsuas qhov voltage ntawm qhov ntsuas qhov ntsuas thiab hloov nws mus rau hauv tus nqi tam sim no ntawm lub roj teeb raug them lossis tawm. Lub sijhawm tiag tiag (RTC) muab kev koom ua ke ntawm tus nqi tam sim no nrog lub sijhawm, kom paub tias muaj pes tsawg coulombs ntws los ntawm.

Daim duab 7. Cov txheej txheem ua haujlwm yooj yim ntawm Coulomb ntsuas txoj kev

Txoj kev ntsuas Coulomb tuaj yeem xam qhov tseeb ntawm lub sijhawm them nqi thaum them lossis tso tawm. Nrog rau tus nqi coulomb txee thiab qhov tso tawm coulomb txee, nws tuaj yeem xam cov peev txheej seem (RM) thiab tag nrho cov nqi them (FCC). Nyob rau tib lub sijhawm, qhov seem muaj peev xwm (RM) thiab lub peev xwm them tag nrho (FCC) kuj tuaj yeem siv los xam cov nqi ntawm lub xeev, uas yog (SOC = RM / FCC). Tsis tas li ntawd, nws tseem tuaj yeem kwv yees lub sijhawm ntxiv, xws li lub zog qaug zog (TTE) thiab tag nrho lub zog (TTF).

Figure 8. Calculation formula of Coulomb measurement method

Muaj ob yam tseem ceeb uas ua rau muaj qhov sib txawv ntawm qhov tseeb ntawm Coulomb ntsuas txoj kev. Qhov thib ib yog qhov tsub zuj zuj ntawm offset yuam kev hauv kev ntsuas tam sim no thiab ADC ntsuas. Txawm hais tias qhov kev ntsuas qhov yuam kev nrog cov cuab yeej siv tam sim no tseem me me, yog tias tsis muaj txoj hauv kev zoo los tshem tawm, qhov yuam kev yuav nce ntxiv nrog lub sijhawm. Daim duab hauv qab no qhia tau hais tias nyob rau hauv kev siv tswv yim, yog tias tsis muaj kev kho nyob rau hauv lub sij hawm ncua sij hawm, qhov kev ua yuam kev ntau yog unlimited.

Daim duab 9. Kev ua yuam kev ntawm Coulomb ntsuas txoj kev

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.

Daim duab 10. Cov xwm txheej rau kev tshem tawm qhov yuam kev ntawm Coulomb ntsuas txoj kev

Qhov thib ob qhov tseem ceeb ua rau qhov sib txawv ntawm qhov tseeb ntawm txoj kev ntsuas coulomb yog qhov yuam kev tag nrho (FCC), uas yog qhov sib txawv ntawm tus nqi ntawm lub roj teeb tsim muaj peev xwm thiab qhov tseeb tag nrho lub peev xwm ntawm lub roj teeb. Lub peev xwm them tag nrho (FCC) yuav raug cuam tshuam los ntawm qhov kub thiab txias, kev laus, kev thauj khoom thiab lwm yam. Yog li ntawd, txoj kev rov kawm dua thiab kev them nyiaj rov qab ntawm cov nqi them tag nrho yog qhov tseem ceeb heev rau txoj kev ntsuas coulomb. Cov duab hauv qab no qhia txog qhov tshwm sim tshwm sim ntawm lub xeev tus nqi yuam kev thaum lub peev xwm them tag nrho yog overestimated thiab underestimated.

Daim duab 11. Qhov kev ua yuam kev thaum lub peev xwm them tag nrho yog overestimated thiab underestimated

2.4 Dynamic voltage algorithm roj ntsuas

Lub dynamic voltage algorithm roj ntsuas ntsuas tuaj yeem xam lub xeev tus nqi ntawm lithium roj teeb raws li cov roj teeb hluav taws xob nkaus xwb. Txoj kev no yog kwv yees qhov nce lossis txo qis ntawm lub xeev tus nqi raws li qhov sib txawv ntawm lub roj teeb voltage thiab qhov qhib hluav taws xob hluav taws xob ntawm lub roj teeb. Cov ntaub ntawv voltage dynamic tuaj yeem simulate tus cwj pwm ntawm lithium roj teeb los txiav txim lub xeev ntawm SOC (%), tab sis txoj kev no tsis tuaj yeem kwv yees tus nqi roj teeb (mAh).

Nws txoj kev suav yog raws li qhov sib txawv ntawm cov roj teeb hluav taws xob thiab qhov qhib hluav taws xob hluav taws xob, los ntawm kev siv cov algorithm rov qab los xam txhua qhov nce lossis txo qis ntawm lub xeev tus nqi los kwv yees lub xeev tus nqi. Piv nrog rau cov kev daws teeb meem ntawm coulomb metering roj ntsuas, qhov ntsuas hluav taws xob dynamic algorithm roj ntsuas yuav tsis suav qhov yuam kev dhau sijhawm thiab tam sim no. Coulomb metering roj gauges feem ntau ua rau qhov kev kwv yees tsis raug ntawm lub xeev ntawm kev them nqi vim qhov tsis txaus ntseeg tam sim no thiab roj teeb tus kheej tso tawm. Txawm hais tias qhov yuam kev tam sim no muaj tsawg heev, lub coulomb txee yuav txuas ntxiv mus ua qhov yuam kev, thiab qhov yuam kev sib sau tuaj yeem raug tshem tawm tsuas yog thaum nws them tag nrho lossis tag nrho tawm.

Lub dynamic voltage algorithm roj ntsuas ntsuas ntsuas lub xeev ntawm tus nqi ntawm lub roj teeb nkaus xwb los ntawm cov ntaub ntawv voltage; vim tias nws tsis yog kwv yees los ntawm cov ntaub ntawv tam sim no ntawm lub roj teeb, nws tsis suav nrog qhov yuam kev. Txhawm rau txhim kho qhov tseeb ntawm lub xeev tus nqi, lub dynamic voltage algorithm yuav tsum tau siv cov khoom siv tiag tiag, thiab kho qhov tsis zoo ntawm qhov kev ua kom zoo tshaj plaws raws li lub roj teeb hluav taws xob tiag tiag thaum nws tau them tag nrho thiab tawm tag nrho.

Daim duab 12. Kev ua tau zoo ntawm dynamic voltage algorithm roj gauge thiab nce optimization

Cov hauv qab no yog qhov ua tau zoo ntawm dynamic voltage algorithm nyob rau hauv txawv paug tus nqi tej yam kev mob. Nws tuaj yeem pom los ntawm daim duab uas nws lub xeev tus nqi muaj qhov raug zoo. Txawm hais tias qhov kev tso tawm ntawm C / 2, C / 4, C / 7 thiab C / 10, tag nrho lub xeev ntawm kev them nqi yuam kev ntawm txoj kev no tsawg dua 3%.

Daim duab 13. Kev ua tau zoo ntawm lub xeev tus nqi ntawm cov dynamic voltage algorithm nyob rau hauv txawv paug tus nqi tej yam kev mob

Daim duab hauv qab no qhia txog kev ua haujlwm ntawm lub xeev ntawm kev them nqi thaum lub roj teeb luv luv thiab tawm luv luv. Lub xeev ntawm kev them nqi yuam kev tseem me me, thiab qhov yuam kev siab tshaj plaws tsuas yog 3%.

Daim duab 14. Kev ua haujlwm ntawm lub xeev tus nqi ntawm cov dynamic voltage algorithm thaum lub roj teeb yog luv luv thiab luv-tso tawm

Piv nrog rau qhov xwm txheej uas Coulomb metering roj ntsuas qhov ntsuas feem ntau ua rau lub xeev tsis raug vim qhov kev paub tsis raug tam sim no thiab roj teeb tus kheej tso tawm, lub zog hluav taws xob algorithm tsis suav qhov yuam kev dhau sijhawm thiab tam sim no, uas yog qhov zoo dua. Vim tias tsis muaj cov ntaub ntawv hais txog tus nqi / tso tawm tam sim no, lub zog hluav taws xob algorithm muaj qhov tsis zoo rau lub sijhawm luv luv thiab lub sijhawm teb qeeb. Tsis tas li ntawd, nws tsis tuaj yeem kwv yees lub peev xwm them tag nrho. Txawm li cas los xij, nws ua tau zoo nyob rau hauv cov nqe lus ntawm qhov raug mus sij hawm ntev, vim hais tias lub roj teeb voltage yuav ncaj qha cuam tshuam nws lub xeev ntawm tus nqi.