Microsoft PowerPoint - 02_電池管理系統簡介01.pptx

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且刃汪
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2 大綱名稱定義鋰離子電池芯 : 形式安全性安全工作區效率壽命鋰離子 BMS: 定義功能鋰離子電池 :SOC DOD 容量平衡 SOH 2

3 名稱定義 (Naming Convections) 電池芯 (Cell) The most basic element of a battery, providing 3V to 4V in the case of Li-Ion Block A collection of cells wired directly in parallel, also providing 3V to 4V 電池 (Battery) A collection of cells (or blocks) wired in series, and constituting a single physical modules, providing a higher voltage, e.g., a battery module that uses for cells in series to provide 12 V nominally 電池組 (Pack or battery pack) A collection of batteries, arranged in any series and/or parallel combination 3

4 電阻 (Resistance) DC series resistance refers to what flowing through the cell. The resistance provided by the specification of the manufacturer refers to the AC impedance, not DC series resistance, which is the term that the user needs to know. In this lecture, the term resistance refers to the internal DC series resistance of a cell or battery. 4

5 鋰離子電池 (Li-Ion Cells) Highest energy density Highest power density Capable of amazing performance, e.g., driving the motor. Standard choice for laptop computers, cell phones, and vehicles. 5

6 包裝形式 (Formats) Formats: cylindrical(small/large), prismatic, and pouch. K2 Energy assembles a set of small cylindrical cells in a prismatic case, forming a battery that has the mechanical and thermal advantages of small cylindrical cells and the convenience of prismatic cells. 6

7 不同電池包裝形式的比較 7

8 安全性 (Safety) Li-Ion cells perform magnificently, but are rather un forgiving if operated outside a rather tight safety operating area (SOA), with consequences ranging from the annoying to the dangerous. Abusing Li-Ion cell in particular ways can be extremely dangerous and can result in physical damage (piercing, crushing) and/or overheating (from over-voltage, voltage over-current, or external heat). 8

9 案例 1: 直接短路 Li-Ion battery on the fire after a direct short circuit across it. 9

10 案例 1: 直接短路 The same battery after the fire. 10

11 案例 2: 著火 Remains of a Prius PHEV after its Li-Ion traction pack caught fire. 11

12 安全性 (Safety) No one got hurt in either event. In both cases, human error was at fault: poor mechanical design and bad manufacturing processes (no quality control and distractions ti present in the manufacturing area). In neither case was a BMS to blame. Those are extreme examples. However, unlikely l such events may be, let them serve as a warning of how dangerous large Li-Ion batteries can be. Be safe when working on such a battery. 12

13 安全性 (Safety) Think clearly, and categorically tell people nearby to be quiet chitchat and Li-Ion do not mix. Wear proper safety equipment: goggles and insulated gloves for working with batteries above 40 V. Do not place metal objects on a plane that is higher than unprotected cells as gravity will invariably cause those objects to fall on the cells. Design batteries properly, and build them according to the design, using tight quality control. Prepare a procedure to follow in case a battery should ignite, before you work on a battery, know that procedure by heart, and be prepared to complete it within 10 seconds of the starting event. 13

14 安全工作區 (SOA) The SOA of Li-Ion cells is bound by current, temperature, and voltage. Li-Ion cells will be quickly damaged and may burst into flames if overcharged above a certain voltage. Most Li-Ion cells will be damaged if allowed to be discharged below a certain voltage. The life time of Li-Ion cells will be drastically reduced if discharged outside a certain temperature range, or charged outside an even tighter temperature range. Li-Ion cells can experience a thermal runaway and ignite if allowed to exceed a safety temperature. 14

15 安全工作區 (SOA) Li-Ion cells lifetime will be reduced if discharged at too high h a current, or charged too fast. Li-Ion cells may be damaged if operated at high pulse current for more than a few seconds. These limits vary considerably with the chemistry of the cell. For examples, Li-Ion cells (LiC 2 ) will go into thermal runaway at a relatively low temperature. LiFePO4 cells are intrinsically immune to thermal runaway. These limits vary to a certain extend with the manufacturer. 15

16 安全工作區 (SOA) 16

17 效率 (Efficiency) Energy The resistance of a Li-Ion cells is quite low (especially in a so-called power cell), which means that little I 2 R power is waste in heat inside of them. M1 26,650 cells from A123 with a load at 1C (2.3 A) Waste: P = 2.32 * 10 mω = 53 mw Delivering: P = 2.3A * 3.2V = 7.6 W Efficiency: 99.3% (98.6% round trip when considering both charging g and discharging). g) At higher currents the energy efficiency of a cell goes down. Maximum power can be extracted from a cell when the load s resistance is equal to the cell s resistance. 17

18 效率 (Efficiency) An M1 26,650 cell from A123 can generate 150A and 500W this way, 250W of which is in heat inside the cells. This can only be sustained for a very short time (less than 10 seconds), as the heat in the cell will quickly degrade it and increase its temperature to dangerous levels. Still, this is something to consider for a race vehicle, for which breaking records is more important than saving life of the cells, and for which the occasional fire is acceptable. 18

19 效率 (Efficiency) Charge From a charge standpoint, Li-Ion cells are practically 100% efficient (as long as a charge and discharge cycle is completed within a time that t is short enough that self leakage is not an issue). The curves in specification sheet are at constant current, and stop when the cell voltage under load drops down to a certain level. At that point the cell is not yet fully discharged. 19

20 效率 (Efficiency) 20

21 Calendar Life 21

22 循環壽命 (Cycle Life) The capacity decreased linearly with the number of charge and discharge cycles. The resistance drops a little and then increases with the number of cycles. 22

23 循環壽命 (Cycle Life) While a portion of the capacity loss is indeed due to a loss of active material inside the cell, the rest is not really lost, but is just simply unused; the cell is undercharged d and underdischarged di d due to the increase of resistance and the fixed cutoff voltages specified by the manufacturers. The portion of that capacity that is unavailable due to increased resistance can be recovered by raising the top cutoff voltage during charge and lowering the bottom cutoff voltage during discharge. 23

24 模型 (Modeling) Electrical equivalent model A chemist thinks of a cell in terms of its processes, while a electrical engineer finds it more useful to view a cell in terms an electrical circuit; that is called the electrical equivalent model. Simple R model The resistance results from the series combination of the effective resistance due to the chemical process and the bulk resistance in the current collectors and terminals. The voltage drop due to this resistance and the cell s current is what chemists call the polarization potential. 24

25 模型 (Modeling) Electrical equivalent models 25

26 模型 (Modeling) Relaxation RC model This allows the model to correctly emulate the actual behavior of a cell when suddenly loaded. A exponentially drop caused by R2C2 time constant (on the order of 1 minute). This is what chemists call relaxation. AC impedance RC model Cell manufacturers use the AC RC model, with an time constant (R3C3) on the order of 1 ms. Cell manufacturers measure this parameter at no load, on a brand new cell, and at 1 KHz, which is a set of conditions that is very different from how the cells are used in the real world. This impedance is pretty constant over the life of the cell, however, it is useless to the cell user. Both RC model 26

27 模型 (Modeling) The dynamic resistance R =Δ V / Δ I The dynamic resistance varies with the current, temperature, SOC, and the cycles. 27

28 電池的串聯電壓鉛酸電池 (lead acid starter battery) 的平衡與不平衡 The delta voltage among cells is perfectly acceptable; lead acid cells are much more tolerant to variances in their voltage. 28

29 電池的串聯電壓鋰聚合物電池 (Li-Po battery): 當串接二顆電池, 以 8.4 V 進行充電平衡時, 二顆電池跨壓皆為 4.2 V 不平衡時, 若有一顆電池為 33V, 3.3 則另一顆電池將充電翅 49V, 4.9 超過 Li-Po 電池之最大額定電壓 4.2 V 但仍然處在一安全範圍, 而不至於造成 Thermal runaway 和著火 29

30 電池的串聯電壓當電池芯 (cell) 串接組成一個高電壓之電池 (battery) 時, 發生電池芯 (cell) 之跨壓不平均之機會愈高這會發生在任何一種材料之充電電池鋰離子電池 (Li-Ion cell): 對於過充電之保護較為脆弱, 當電荷到達飽和, 便無法再承受多餘的電荷, 因此當串連時, 其他電池尚未到達飽和, 而有電流通過時, 該 Li-Ion 電池之電壓會急遽上升, 而到達危險的邊緣 30

31 電池的串聯電壓因此, 一個充電器 (CCCV charger, Constant current constant voltage charger) 依靠電池的總電壓來決定何時停止充電, 會產生安全性問題可能造成某些電池芯過充電 (Overcharging) 因此, 需要電池管理系統 (BMS) 對電池芯進行監控和平衡, 以平衡電池並使電池發揮最大之效能 31

32 電池的串聯電壓當四個串接之電池芯放電至最低電壓 12 V 時, 平衡時, 每個電池芯之跨壓皆為 3.0 V 不平衡時, 可能造成某一電池芯之電壓過低 Li-Ion 電池對於過放電 (Overdischarging) 之保護較差, 當電壓低於其額定電壓, 會造成不可逆之破壞因此, 需要電池管理系統 (BMS) 對電池芯進行監控和平衡, 以平衡電池並使電池發揮最大之效能 32

33 鋰離子電池管理系統 (Li-Ion BMS) 電池管理系統 (BMS, Battery management system) 之目的在於確保電池中之每一個電池芯皆處在安全工作區域 (SOA) 這對大的鋰離子電池尤其重要鋰離子電池相較於其他材質的電池, 鋰離子電池更不容許濫用 (abuse) 在大的電池中, 不管是充電狀態或是放電狀態, 串接之鋰離子電池芯更容易發生不平衡之現象 33

34 電池管理系統的定義電池管理系統 (BMS, Battery management system): 電池管理系統並沒有一個學理上明確之定義, 因此有部分類似之名稱, 如 VMS (Voltage management system) 和 PCM (Protection circuit module) 本書稱以任何方法對於電池進行保護之技術或產品, 稱之為電池管理系統電池管理系統包含以下功能監控電池 (To monitor the battery) 保護電池 (To protect the battery) 計算電池狀態 (To estimate the battery s state) 讓電池之效能 (Performance) 發揮到最大對使用者或外部元件, 報告 (Report) 電池狀態 34

35 Li-Ion BMS 的功能為了安全性, 一個鋰離子電池保護系統必須至少包含以下功能, 重要性由高至低排列 : 藉由關閉充電電流或命令 (request) 其關閉, 以避免任何電池芯之跨壓超過其額定電壓藉由關閉充電電流命令其關閉或啟動冷卻機制 (Cooling), 避免任何電池芯超過其額定溫度藉由關閉放電電流或命令其關閉, 以避免任何電池芯之跨壓低於其額定電壓藉由直接關閉充電電流或命令其關閉, 以避免充電電流超過其額定值 ( 充電電流之大小會因電壓溫度或先前之電流值而異 ) 藉由直接關閉放電電流或命令其關閉, 以避免放電電流低於其額定值 35

36 Li-Ion BMS 的功能 BMS 在電池充電時之保護機制 : 任意一個電池芯到達其額定電壓時, 必須關掉充電器, 等待電池電壓下降後, 再繼續充電 36

37 Li-Ion BMS 的功能 BMS 在電池放電時之保護機制 : 任意一個電池芯低於其額定電壓時, 必須關掉負載 37

38 客製化或現成產品克制化 : 獨有可完全掌控現成產品 : 快速簡單便宜需要客製化的對象 : 需要完全掌控產品特性之大型製造公司想要強化產品線之大型電子公司想要增加價值之公司想要學習經驗之有興趣的人需要現成產品之對象 : 設計 EV PHEV HEV 汽車之公司電池芯製造商和電池整合公司 EV 轉換器 38

39 客製化或現成產品使用客製化或現成產品之利弊 39

40 鋰離子電池 (Li-Ion Batteries) 電荷狀態 (SOC, State of charge): 電荷狀態係用來計算電池之容量的參數其定義為可獲得之電荷除以充飽時之總電荷之比值單位為 %, 由 100% ~ 0% 在電動車 (EV) 中,SOC 可視為傳統之油表的角色放電深度 (DOD, Depth of discharge) 放電深度係計算電池或電池芯流失的電荷量之參數單位為安時 (Ah, Amp-hour) 鉛酸電池 (Lead Acid batteries) 常以 % 為 DOD 之單位 40

41 鋰離子電池 (Li-Ion Batteries) 使用 % 為 SOC 之單位, 搭配 Ah 為單位之 DOD, 可以提供使用者更完整之資訊假設一容量為 100 Ah 之電池芯, 實際上具有 105 Ah 之電量當完全放電時,SOC 為 0%, 而 DOD 可表示為 100% 或 100 Ah 但實際上為 105 Ah 41

42 鋰離子電池 (Li-Ion Batteries) 乍看之下,SOC 似乎與 DOD 呈現反比之關係, 但其實不然完全放電時,DOD 無法計算 42

43 鋰離子電池 (Li-Ion Batteries) 當一個容量 (Capacity) 為 100 Ah 之電池芯, 容量降低為 50 Ah 時, 使用 SOC(%) 和 DOD(Ah) 可看出電池之狀態正常的容量, 是由製造商提供之數據 43

44 容量 (Capacity) 有效的電池芯容量 (Capacity), 係由何時停止充電何時停止放電所決定電池製造商為了電池的安全性, 規定了電池的正常使用電壓及電流之範圍, 使用者依照此規定範圍去使用該電池, 決定了該電池之有效容量 44

45 容量 (Capacity) 電池芯之充電電流和放電電流會影響有效的電池容量當使用微小之放電電流時, 電池芯之端電壓 (Terminal voltage) 等於電池之內電壓或開路電壓 (OCV, Open circuit it voltage) 因此, 當電池芯達到其低截止電壓 (low cutoff voltage) 時, 該電池芯處於完全放電 (Fully discharged) 當使用大的放電電流時, 電池芯之端電壓會提前達到其低截止電壓, 此時該電池尚未完全放電, 造成電池芯容量在高放電率 (High discharge rate) 時會降低電池芯之實際容量並未改變, 但其有效容量卻因高的放電電流而變小 45

46 容量 (Capacity) 藉由量測電池芯之電阻值 (Resistance), 可使用 IR 補償端電壓與開路電壓之間之差異, 延遲停止放電之時機, 以獲取電池之最大容量但在低截止電壓為 1/2 OCV 甚至更低時, 此方法不可行 46

47 容量 (Capacity) 在充電時, 製造商建議電池芯使用定電流充電直到高截止電壓 (Top cutoff voltage) 後, 改為使用定電壓方式, 可繼續充電直到充電電流降到一特定值後停止使用上述方法進行充電時, 考量 IR 壓降之限制, 在定電流模式下充電, 因為 IR 壓降, 使得端電壓提早到達高截止電壓使得定電流模式提前結束轉為定電壓模式時, 由於充電電流極小,IR 壓降可視為 0, 因此 IR 所導致之容量誤差亦可視為 0 因此, 當充電器停止充電時, 電池芯之 OCV 幾乎等於高截止電壓, 此時, 電池可視為完全充電 (Fully charged) 47

48 容量 (Capacity) 在充電時, 偵測電池芯之電阻值, 透過 IR 補償, 可延後定電流模式停止之時機, 而節省充電所需的時間 48

49 平衡 (Balance and Balancing) 由於個體之差異性, 和經歷的充電歷史不同, 不同的電池芯會在下列四個參數出現不平衡 (Unbalanced) 的現象 : 電荷狀態 (SOC) 漏電流 (Leakage or Self-discharge current) 電阻值 (Resistance) 容量 (Capacity) 通常, 平衡 (Balance) 一詞可用來指上述四個參數, 在不同的電池芯之間達到匹配但在此, 平衡主要用來指 SOC 的匹配 49

50 平衡 (Balance and Balancing) 平衡 (Balancing): 平衡 (Balancing) 係指讓電池中的電池芯之間的 SOC 值取得一致性的過程, 使電池的容量達到最大此平衡的過程主要的對象是前述之第一個參數 SOC 然而, 在平衡 SOC 的過程中, 必須補償電池芯之間 (Cell-to-cell) ll) 的漏電流之差異性, 也就是前述之第二個參數 Leakage 此外, 也必須解決電池芯之電阻值不同的問題, 也就是前述之第三個參數 Resistance 平衡唯一沒有關心的參數是容量 (Capacity) 的匹配, 這必須由另一項技術來完成, 也就是重新分配 (Redistribution) 50

51 平衡 (Balance and Balancing) 有一個常見的錯誤觀念 : 平衡是為了處理電池芯的電阻值之差異性這是錯誤的假設有一個由理想的完全充電之電池芯所組成的電池, 其電池芯之間具有不同的內電阻值當其放在架上未使用時, 電池芯永遠具有 100% 之 SOC, 沒有電流流過其內電阻, 因此, 內電阻之差異不會影響平衡假設上述之電池, 其電池芯之間具有相同的漏電流此時, 所有的電池芯會以極慢的速度放電, 而 SOC 值仍是在原來的狀態由於相較於隔離膜 (Separator) 之大電阻值, 內電阻的變化相對來得小, 因此影響不大 51

52 平衡 (Balance and Balancing) 假設上述之電池進行放電在放電過程, 其電池芯之端電壓會由於 IR 壓降而產生差異, 但當放電電流停止, 其開路電壓 OCV 仍會完全匹配, 只要經過充電, 仍會回到 100% 的 SOC 值, 不需要平衡另一個錯誤的觀念 : 平衡會使電池的所有電荷都能被使用事實是 : 當電池完全放電時, 有部分電池芯仍具有可用之電荷當電池完全充電時, 有部分電池芯仍可接受電荷因此, 電池平衡僅是在充放電過程的某個時刻, 使電池芯具有相同的 SOC 值 52

53 經過一段時間之不平衡由於電池芯間的漏電流之差異,( 不是因為具有漏電流, 也不是因為內電阻的原因 ), 隨著時間的流逝, 電池芯會產生不平衡假設一個電池芯因為漏電流而損失 2Ah 電量而另一個電池芯因為漏電流而損失 3 Ah 電量, 平衡 (Balancing) 所要做的事情, 便是設法將第一個電池芯移出 1 Ah 的電量因此, 平衡並非在補償漏電流, 而是在補償漏電流的差異 53

54 經過一段時間之不平衡理想的電池, 初始為平衡狀態 54

55 經過一段時間之不平衡具有相同漏電流之理想電池, 初始為平衡狀態 55

56 經過一段時間之不平衡具有不同漏電流之電池, 初始為平衡狀態 56

57 起始之不平衡多數時候, 電池在初始的時候便不處於平衡狀態, 而由於漏電流之差異, 造成電池芯之間持續處於不平衡狀態要補償起始之不平衡, 需要移動大量之電荷 57

58 電池 SOC 與電池芯 SOC 充電時, 電池接受電荷之能力取決於第一個達到完全充電之電池芯放電時, 電池釋放電荷之能力取決於第一個達到完全放電之電池芯在電池達到平衡之前, 限制充電之電池芯和限制放電之電池芯是不同的 58

59 電池 SOC 與電池芯 SOC 藉由平衡可以拉開限制充電和放電之極限, 以增加電池的容量當電池處於平衡狀態時, 限制電池充電和放電之極限來自於同一個電池芯 59

60 電池 SOC 與電池芯 SOC 假設有一理想之電池芯所組成之電池, 當電池處於 100% SOC 時, 電池芯也是處於 100% SOC 而電池 0% SOC 的時候, 電池芯也處於 0% SOC 60

61 電池 SOC 與電池芯 SOC 假設有一理想之電池芯所組成之電池處於不平衡狀態, 電池芯 4 率先達到完全充電, 導致電池不能達到 100% SOC 放電時, 電池芯 1 率先達到完全放電, 而電池芯 4 尚有 45% SOC 61

62 電池 SOC 與電池芯 SOC 對於真實的電池, 每一個電池芯的容量是不同的, (Cell 4 的容量最大, 而 Cell 1 的容量最小 ) 因此, 只要有充電或放電的行為, 電池的 SOC 便會處於不平衡狀態 62

63 電池 SOC 與電池芯 SOC 電池平衡於 50% SOC ( 所有電池芯同時處於 50% SOC ) 63

64 電池 SOC 與電池芯 SOC 電池平衡於 0% SOC ( 所有電池芯同時處於 0% SOC ) 64

65 電池 SOC 與電池芯 SOC 電池芯之充放電斜率 ( 和電池芯的容量有關 ) 和之前相同, 但電池容量減少將近一半 65

66 電池 SOC 與電池芯 SOC 極端的例子, 電池嚴重地不平衡, 使得電池無法使用 66

67 健康狀態 (SOH) 健康狀態 (SOH, State of health): 健康狀態是指電池包 (Battery pack) 之實際條件和正常調見之比例, 單位為 % 當健康狀態為 100% 時, 表示電池符合規格 (Specifications) 之條件不同的製造商定義之健康狀態會有不同健康狀態可用來表示一個電池目前的條件是否足夠應付其應用也可以用來計算在這個應用當中, 其有效的壽命健康狀態的計算方式是不固定的, 因為並非測量特定的物理量一個 BMS 計算 SOH 的公式, 通常是他的商業機密 67

68 健康狀態 (SOH) 二個或數個未滿足某特定規格之電池或電池芯, 並聯後滿足該特定規格, 則此並聯之電池或電池芯為 100% SOH 68

Microsoft Word - Lenovo_L15M3PB2 (Winbook)_3S1P_UN38.3 Test Report_SLEU

Microsoft Word - Lenovo_L15M3PB2 (Winbook)_3S1P_UN38.3 Test Report_SLEU Lithium-ion Battery UN38.3 Test Report Recommendations on the TRANSPORT OF DANGEROUS GOODS (Manual of Tests and Criteria, Fifth revised edition, Amend.2) Customer: Lenovo Model: L15M3PB2 Rating: 11.25V,