1. Introduction to Lithium Ion Battery

1.1 To’lov holati (SOC)

Zaryadlanish holatini batareyadagi mavjud elektr energiyasining holati sifatida aniqlash mumkin, odatda foiz sifatida ifodalanadi. Mavjud elektr energiyasi zaryad va zaryadsizlanish oqimi, harorat va qarish hodisalariga qarab o’zgarganligi sababli, zaryad holatining ta’rifi ham ikki turga bo’linadi: mutlaq zaryad holati (ASOC) va nisbiy zaryad holati (nisbiy holat). -Of-Charge;ASOC) State-Of-Charge; RSOC). Odatda zaryadlash diapazonining nisbiy holati 0% -100%, batareya to’liq zaryadlanganda 100% va to’liq zaryadsizlanganda 0% bo’ladi. Zaryadning mutlaq holati – akkumulyator ishlab chiqarilganda mo’ljallangan belgilangan quvvat qiymatiga muvofiq hisoblangan mos yozuvlar qiymati. To’liq zaryadlangan yangi batareyaning mutlaq zaryad holati 100% ni tashkil qiladi; va hatto eskirgan batareya to’liq zaryadlangan bo’lsa ham, har xil zaryadlash va zaryadsizlanish sharoitida u 100% ga erisha olmaydi.

Quyidagi rasmda turli deşarj stavkalarida kuchlanish va batareya quvvati o’rtasidagi bog’liqlik ko’rsatilgan. Bo’shatish tezligi qanchalik yuqori bo’lsa, batareya quvvati shunchalik past bo’ladi. Harorat past bo’lsa, batareya quvvati ham kamayadi.

Shakl 1.

Har xil zaryadsizlanish tezligi va haroratlarda kuchlanish va quvvat o’rtasidagi bog’liqlik

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 To’liq zaryadlangan

Batareya kuchlanishi va eng yuqori zaryadlash kuchlanishi o’rtasidagi farq 100 mV dan kam bo’lsa va zaryadlash oqimi C/10 ga tushsa, batareya to’liq zaryadlangan deb hisoblanishi mumkin. Batareyaning xususiyatlari har xil va to’liq zaryadlash shartlari ham boshqacha.

Quyidagi rasmda lityum batareyani zaryad qilishning odatiy egri chizig’i ko’rsatilgan. Batareyaning kuchlanishi eng yuqori zaryadlash kuchlanishiga teng bo’lganda va zaryadlash oqimi C / 10 ga tushganda, batareya to’liq zaryadlangan hisoblanadi.

Shakl 2. Lityum batareyani zaryadlash xarakteristikasi egri chizig’i

1.4 Mini zaryadsizlantirish kuchlanishi

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 To’liq zaryadsizlanish

Batareyaning kuchlanishi minimal zaryadsizlanish kuchlanishidan kam yoki unga teng bo’lsa, uni to’liq zaryadsizlantirish deb atash mumkin.

1.6 Zaryadlash va tushirish tezligi (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 Tsiklning ishlash muddati

Davrlar soni – bu batareyaning to’liq zaryadlash va zaryadsizlanishini necha marta sodir bo’lganligi, bu haqiqiy zaryadsizlanish quvvati va dizayn hajmidan baholanishi mumkin. To’plangan tushirish quvvati loyiha quvvatiga teng bo’lganda, aylanishlar soni bir marta. Odatda 500 ta zaryadlash va tushirish tsiklidan so’ng, to’liq zaryadlangan batareyaning quvvati 10% ~ 20% ga kamayadi.

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

1.8 O’z-o’zidan zaryadsizlanish

Haroratning oshishi bilan barcha batareyalarning o’z-o’zidan zaryadsizlanishi ortadi. O’z-o’zidan tushirish, asosan, ishlab chiqarish nuqsoni emas, balki batareyaning o’ziga xos xususiyatlari. Shu bilan birga, ishlab chiqarish jarayonida noto’g’ri ishlash ham o’z-o’zidan zaryadsizlanishning ko’payishiga olib kelishi mumkin. Odatda, batareya haroratining har 10 ° C oshishi uchun o’z-o’zidan zaryadsizlanish tezligi ikki baravar ortadi. Lityum-ion batareyalarning oylik o’z-o’zidan zaryadsizlanishi taxminan 1 ~ 2% ni tashkil qiladi, har xil nikel asosidagi batareyalarning oylik o’z-o’zidan zaryadsizlanishi 10-15% ni tashkil qiladi.

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

2. Batareya yonilg’i o’lchagichiga kirish

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 Ochiq zanjirli kuchlanish usuli

Ochiq kontaktlarning zanglashiga olib keladigan kuchlanish usulidan foydalangan holda elektr hisoblagichni amalga oshirish osonroq va uni ochiq kontaktlarning zanglashiga olib keladigan kuchlanish holatiga mos keladigan jadvalni izlash orqali olish mumkin. Ochiq kontaktlarning zanglashiga olib keladigan gipotetik holati, batareya taxminan 30 daqiqa davomida dam olganida batareya terminali kuchlanishidir.

Turli xil yuk, harorat va batareyaning qarishi ostida batareyaning kuchlanish egri chizig’i boshqacha bo’ladi. Shuning uchun, qattiq ochiq elektron voltmetr zaryad holatini to’liq ifodalay olmaydi; Jadvalni ko’zdan kechirish orqali zaryad holatini baholab bo’lmaydi. Boshqacha qilib aytganda, agar zaryad holati faqat jadvalga qarab baholansa, xato juda katta bo’ladi.

Quyidagi rasm shuni ko’rsatadiki, bir xil batareya zo’riqishida zaryad va zaryadsizlanish ostida va ochiq elektron kuchlanish usuli bilan topilgan zaryad holati juda boshqacha.

Shakl 5. Zaryadlash va zaryadsizlantirish ostida batareyaning kuchlanishi

Quyidagi rasm zaryadsizlanish vaqtida turli xil yuklar ostida zaryad holati juda katta farq qilishini ko’rsatadi. Shunday qilib, asosan, ochiq kontaktlarning zanglashiga olib keladigan kuchlanish usuli faqat qo’rg’oshin-akkumulyator batareyalari yoki avtomobillarda uzluksiz quvvat manbalaridan foydalanish kabi zaryad holatining aniqligiga past talablarga ega bo’lgan tizimlar uchun javob beradi.

Shakl 6. Bo’shatish vaqtida turli xil yuklar ostida batareyaning kuchlanishi

2.3 Kulon o’lchash usuli

Kulon o’lchash usulining ishlash printsipi batareyaning zaryadlash / tushirish yo’lida aniqlash qarshiligini ulashdir. ADC aniqlash rezistoridagi kuchlanishni o’lchaydi va uni zaryadlangan yoki zaryadsizlangan batareyaning joriy qiymatiga aylantiradi. Haqiqiy vaqt hisoblagichi (RTC) qancha kulon o’tishini bilish uchun joriy qiymatni vaqt bilan birlashtirishni ta’minlaydi.

Shakl 7. Kulon o’lchash usulining asosiy ish usuli

Coulomb o’lchash usuli zaryadlash yoki zaryadlash paytida zaryadning real vaqt holatini aniq hisoblashi mumkin. Zaryadlash kulon hisoblagichi va tushirish kulon hisoblagichi bilan u qolgan quvvatni (RM) va to’liq zaryad hajmini (FCC) hisoblashi mumkin. Shu bilan birga, qolgan quvvat (RM) va to’liq zaryadlash hajmi (FCC) zaryad holatini hisoblash uchun ham ishlatilishi mumkin, ya’ni (SOC = RM / FCC). Bundan tashqari, u qolgan vaqtni ham taxmin qilishi mumkin, masalan, quvvat tugashi (TTE) va to’liq quvvat (TTF).

Figure 8. Calculation formula of Coulomb measurement method

Coulomb o’lchash usulining aniqligida og’ishlarni keltirib chiqaradigan ikkita asosiy omil mavjud. Birinchisi, oqim sezish va ADC o’lchashda ofset xatolarining to’planishi. Amaldagi texnologiya bilan o’lchash xatosi hali ham kichik bo’lsa-da, uni bartaraf etishning yaxshi usuli bo’lmasa, vaqt o’tishi bilan xatolik ortadi. Quyidagi rasm shuni ko’rsatadiki, amaliy ilovalarda, agar vaqt davomiyligida tuzatish bo’lmasa, to’plangan xato cheksizdir.

Shakl 9. Kulon o’lchash usulining kümülatif xatosi

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.

Shakl 10. Kulon o’lchash usulining kümülatif xatosini bartaraf etish shartlari

Kulon o’lchash usulining aniqligining og’ishiga olib keladigan ikkinchi asosiy omil – bu to’liq zaryadlash hajmi (FCC) xatosi, bu batareyaning dizayn hajmining qiymati va batareyaning haqiqiy to’liq zaryadlash hajmi o’rtasidagi farqdir. To’liq zaryadlash hajmiga (FCC) harorat, qarish, yuk va boshqa omillar ta’sir qiladi. Shuning uchun, to’liq zaryad quvvatini qayta o’rganish va kompensatsiya qilish usuli kulon o’lchash usuli uchun juda muhimdir. Quyidagi rasmda to’liq zaryadlash quvvati haddan tashqari oshirilgan va kam baholanganda zaryad xatosi holatining tendentsiya hodisasi ko’rsatilgan.

Shakl 11. To’liq zaryadlash quvvati ortiqcha va kam baholanganda xato tendentsiyasi

2.4 Dinamik kuchlanish algoritmi yonilg’i o’lchagichi

Dinamik kuchlanish algoritmi yonilg’i o’lchagichi lityum batareyaning zaryad holatini faqat batareyaning kuchlanishiga qarab hisoblashi mumkin. Ushbu usul batareya zo’riqishida va batareyaning ochiq tutashuv kuchlanishi o’rtasidagi farq asosida zaryad holatining oshishi yoki kamayishini taxmin qilishdir. Dinamik kuchlanish ma’lumotlari SOC (%) zaryad holatini aniqlash uchun lityum batareyaning harakatini samarali tarzda simulyatsiya qilishi mumkin, ammo bu usul batareya quvvati qiymatini (mAh) taxmin qila olmaydi.

Uning hisoblash usuli batareya zo’riqishida va ochiq kontaktlarning zanglashiga olib keladigan kuchlanish o’rtasidagi dinamik farqga asoslangan bo’lib, zaryad holatini baholash uchun zaryad holatining har bir ortishi yoki pasayishini hisoblash uchun iterativ algoritmdan foydalanadi. Kulon o’lchash yonilg’i o’lchagichining yechimi bilan solishtirganda, dinamik kuchlanish algoritmi yonilg’i o’lchagichi vaqt va oqim bo’yicha xatolarni to’plamaydi. Coulomb yonilg’i o’lchagichlari odatda oqim sezish xatolari va batareyaning o’z-o’zidan zaryadsizlanishi tufayli zaryad holatini noto’g’ri baholashga olib keladi. Joriy sezish xatosi juda kichik bo’lsa ham, kulon hisoblagichi xatoni to’plashni davom ettiradi va to’plangan xato faqat to’liq zaryadlangan yoki to’liq zaryadsizlanganda yo’q qilinishi mumkin.

Dinamik kuchlanish algoritmi yonilg’i o’lchagichi batareyaning zaryadlanish holatini faqat kuchlanish ma’lumotlari bilan baholaydi; chunki u batareyaning joriy ma’lumotlari bilan hisoblanmaydi, u xatolarni to’plamaydi. Zaryad holatining aniqligini oshirish uchun dinamik kuchlanish algoritmi haqiqiy qurilmadan foydalanishi va to’liq zaryadlangan va to’liq zaryadsizlanganda batareyaning haqiqiy kuchlanish egri chizig’iga muvofiq optimallashtirilgan algoritm parametrlarini sozlashi kerak.

Shakl 12. Dinamik kuchlanish algoritmi yonilg’i o’lchagichining ishlashi va daromadni optimallashtirish

Quyida turli tushirish tezligi sharoitida dinamik kuchlanish algoritmining ishlashi keltirilgan. Rasmdan ko’rinib turibdiki, uning zaryad holati yaxshi aniqlikka ega. C/2, C/4, C/7 va C/10 deşarj shartlaridan qat’i nazar, ushbu usulning zaryadlash xatosining umumiy holati 3% dan kam.

Shakl 13. Har xil zaryadsizlanish tezligi sharoitida dinamik kuchlanish algoritmining zaryad holatining ishlashi

Quyidagi rasmda batareya qisqa zaryadlangan va qisqa zaryadsizlanganda zaryad holatining ishlashi ko’rsatilgan. Zaryad holatidagi xato hali ham juda kichik va maksimal xatolik atigi 3% ni tashkil qiladi.

Shakl 14. Batareya qisqa zaryadlangan va qisqa muddatda zaryadsizlanganda dinamik kuchlanish algoritmining zaryad holatining ishlashi.

Coulomb o’lchash yonilg’i o’lchagichi odatda oqim sezish xatolari va batareyaning o’z-o’zidan zaryadsizlanishi tufayli noto’g’ri zaryad holatini keltirib chiqaradigan holat bilan solishtirganda, dinamik kuchlanish algoritmi vaqt va oqim davomida xatolarni to’plamaydi, bu katta afzallikdir. Zaryadlash / tushirish oqimi haqida hech qanday ma’lumot yo’qligi sababli, dinamik kuchlanish algoritmi zaif qisqa muddatli aniqlik va sekin javob vaqtiga ega. Bundan tashqari, u to’liq zaryad hajmini taxmin qila olmaydi. Biroq, u uzoq muddatli aniqlik nuqtai nazaridan yaxshi ishlaydi, chunki akkumulyator kuchlanishi oxir-oqibat uning zaryad holatini bevosita aks ettiradi.