Battery pack and current monitoring method thereof
By detecting the voltage signal of the battery pack through a current monitoring system, calculating the current value, and controlling the current path switch, the problem of battery pack protection when the current detection resistor is abnormal is solved, and the safety monitoring and protection of the battery pack is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- RICHTEK TECH
- Filing Date
- 2022-12-28
- Publication Date
- 2026-07-07
Smart Images
Figure CN117650300B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a battery pack, and more particularly to a battery pack and a method for monitoring its current. Background Technology
[0002] Rechargeable battery packs are widely used in the consumer electronics market, covering mobile phones, laptops, game consoles, digital cameras, portable devices, and more. A battery pack is a finished product assembled by welding together battery cells, protection boards, battery wires, nickel plates, auxiliary materials, battery boxes, and battery films. In the consumer electronics field, battery pack technology and the market are mature and growing rapidly. The lower the internal resistance of a battery pack, the higher its output power. Battery output power refers to the battery's ability to output energy per unit time, calculated based on discharge current and discharge voltage. At rated voltage, battery output power increases with increasing electrode surface area and operating temperature, and decreases with decreasing temperature.
[0003] A short circuit occurs when two points with different potentials are incorrectly connected directly or by a conductor with very low impedance (or resistance) in a normal circuit. The short-circuit current is very large, far exceeding the rated current (the ideal current for an appliance), often damaging rechargeable battery packs and even causing fires. Rechargeable battery packs typically have a current-sensing resistor. According to Ohm's law, when current flows through a resistor, a voltage difference is generated across it. Dividing this voltage difference by the resistance value gives the current flowing through the resistor. Using a resistor with a large resistance value to obtain a larger voltage difference can easily lead to overheating. Therefore, a resistor with the smallest possible resistance value should be used for sensing. When a circuit fault causes the current to exceed the normal range, the circuit's protection mechanism can detect the abnormal current by monitoring the voltage across the current-sensing resistor and can cut off the current path, stopping the circuit operation to ensure safety. However, when the current-sensing resistor itself is short-circuited, it is impossible to monitor the voltage across it for current determination. Summary of the Invention
[0004] An embodiment provides a battery pack including a set of battery cells, a current path switch, and a current monitoring system. The current monitoring system includes a signal detection unit, a logic judgment unit, and a current path control unit. The current path switch is coupled to the set of battery cells. The signal detection unit is coupled to the positive terminal of the set of battery cells and / or the battery pack, for detecting at least one voltage signal at the positive terminal of the set of battery cells and / or the battery pack. The logic judgment unit is coupled to the signal detection unit, for generating a calculated value of the at least one voltage signal and generating a logic signal based on the calculated value. The current path control unit is coupled to the logic judgment unit and the current path switch, for controlling the current path switch according to the logic signal.
[0005] An embodiment provides a current monitoring method for a battery pack. The battery pack includes a set of battery cells, a current path switch, and a current monitoring system. The current monitoring system includes a signal detection unit, a logic judgment unit, and a current path control unit. The current path switch is coupled to the set of battery cells, the signal detection unit is coupled to the positive terminal of the set of battery cells and / or the battery pack, the logic judgment unit is coupled to the signal detection unit, and the current path control unit is coupled to the logic judgment unit and the current path switch. The current monitoring method includes the signal detection unit detecting at least one voltage signal at the positive terminal of the set of battery cells and / or the battery pack, the logic judgment unit generating a calculated value of the at least one voltage signal and generating a logic signal based on the calculated value, and the current path control unit controlling the current path switch based on the logic signal. Attached Figure Description
[0006] Figure 1 This is a schematic diagram of the battery pack according to an embodiment of the present invention.
[0007] Figure 2 for Figure 1 A schematic diagram of the battery pack charging process.
[0008] Figure 3 for Figure 2 The signal diagram for charging the battery pack.
[0009] Figure 4 for Figure 1 A schematic diagram of the battery pack discharging.
[0010] Figure 5 for Figure 4 The signal diagram of the battery pack's discharge.
[0011] Figure 6 for Figure 1 Another schematic diagram of the battery pack discharging.
[0012] Figure 7 for Figure 6 The signal diagram of the battery pack's discharge.
[0013] Figure 8 for Figure 1 A flowchart of the current monitoring method for battery packs.
[0014] [Symbol Explanation]
[0015] 100: Battery Pack
[0016] 10: Battery Cell
[0017] 20: Current path switch
[0018] 30: Current monitoring system
[0019] 32: Signal Detection Unit
[0020] 34: Logical Judgment Unit
[0021] 36: Current path control unit
[0022] 60: Current sensing resistor
[0023] P+: Positive terminal of battery pack
[0024] P-: Negative terminal of battery pack
[0025] VCn, VC1, VSS: Cell voltage
[0026] Vpack: Intermediate voltage of the current path
[0027] Vb: Voltage
[0028] ΔVb: Voltage difference
[0029] Vth: Voltage threshold
[0030] S1: Control signal
[0031] Ich: Charging current
[0032] Idsg: Discharge current
[0033] T0~T5: Period
[0034] 800: Method
[0035] S802~S806: Steps Detailed Implementation
[0036] The following description is intended to illustrate the principles of the invention and not to limit its scope. The term "substantially" as used herein includes the numerical values and specific values determined by those skilled in the art within acceptable deviations, taking into account measurement problems and errors. For example, "substantially" may mean within one or more standard deviations. Furthermore, due to variations in electronic device manufacturing processes, the term "same" may also be interpreted as "approximately". In particular, the following description of the invention provides several different embodiments or examples to implement applications with different characteristics. Specific examples of components and arrangements described below are intended to simplify the invention. These descriptions are merely illustrative and not intended to limit the scope of the invention. Additionally, the invention may use repeated reference numerals and / or letters in various examples. The use of repeated reference numerals and / or letters is for simplicity and clarity, and the numerals and / or letters themselves do not necessarily imply a relationship between the various embodiments and / or configurations discussed. Furthermore, in various embodiments of the invention, the connections and / or couplings formed between feature components may include embodiments formed in direct contact, and may also include embodiments formed indirectly by inserting additional features between them.
[0037] Figure 1 This is a schematic diagram of a battery pack 100 according to an embodiment of the present invention. The battery pack 100 includes a set of battery cells 10, a current path switch 20, and a current monitoring system 30. The current monitoring system 30 includes a signal detection unit 32, a logic judgment unit 34, a current path control unit 36, and a current detection resistor 60. The current path switch 20 is coupled to the battery cells 10. The signal detection unit 32 is coupled to the battery cells 10 and the positive terminal P+ of the battery pack, and is used to detect at least one voltage signal of the battery cells 10 and / or the positive terminal P+ of the battery pack 100. That is, the signal detection unit 32 can detect the voltage signal of the battery cells 10 and also detect the voltage signal of the positive terminal P+ of the battery pack 100. The logic judgment unit 34 is coupled to the signal detection unit 32, and is used to generate a calculated value of the voltage signal among the at least one voltage signal and generate a logic signal based on the calculated value. Details of the calculated value will be described in detail below. The current path control unit 36 is coupled to the logic judgment unit 34 and the current path switch 20, and is used to control the current path switch 20 according to the logic signal. A current sensing resistor 60 is coupled between the cell 10 and the negative terminal P- of the battery pack 10, and both ends of the current sensing resistor 60 are coupled to the signal detection unit 32. The negative terminal P- can be grounded. Furthermore, the cell 10 can be composed of multiple cells connected in series. Each cell in the cell 10 can be coupled to the signal detection unit 32, and a corresponding voltage can be measured for each cell, such as VCn, VC1, etc. Voltage VCn represents the highest cell voltage of the cell 10, and VSS represents the ground voltage of the cell 10.
[0038] In practical applications, the signal detection unit 32 can be an analog-to-digital converter (ADC), the logic judgment unit 34 can be an arithmetic logic unit (ALU), and the current path control unit 36 can be any circuit that generates a switch signal. The current path switch 20 can be a transistor, and is not limited to a single transistor; it can be multiple transistors connected in parallel. For example, two N-metal-oxide-semiconductor (NMOS) field-effect transistors can be respectively disposed in the charging path and the discharging path to control the charging and discharging states respectively. The above components are merely examples, and other equivalent circuit components should be included within the scope of this invention.
[0039] Figure 2 for Figure 1 This is a schematic diagram of the charging process of the battery pack 100. When the battery pack 100 is charging, the charging current Ich flows from the positive terminal P+ to the negative terminal P-. Normally, the signal detection unit 32 can detect the voltage across the current sensing resistor 60 to detect the short-circuit current. The maximum instantaneous value of the short-circuit current can be several times the rated current, which may damage electronic components and cause malfunctions. However, when the current sensing resistor 60 malfunctions, the voltage across the current sensing resistor 60 is detected to be 0. At this time, the current monitoring system 30 can replace the current sensing resistor 60 to monitor the charging current in the current path and detect whether a short-circuit current has occurred. The current path control unit 36 can issue a control signal S1 to control the current path switch 20 based on the detection result. In addition, the signal detection unit 32 can set the measured voltage signal to be the measured value of the highest cell voltage to ground (Vb = VCn - VSS), hereinafter referred to as voltage Vb.
[0040] Figure 3 for Figure 2 The signal diagram for charging battery pack 100 is shown. During charging, battery pack 100 is in a normal charging state during cycles T0, T1, and T2. Each cycle can be on the order of nanoseconds to picoseconds. ΔVb within each cycle is the difference between the average voltage Vb of the previous two cycles. Taking cycle T2 as an example, the charging current Ich is at normal flow rate, and the voltage Vb is at normal level. The logic judgment unit 34 calculates the difference ΔVb between the average voltages of the two cycles preceding cycle T2 (ΔVb = Vb). T1 -Vb T0 (i.e., the calculated value mentioned above). Special note: Vb T1 It can be the average value of the voltage Vb within period T1, Vb T0The average voltage Vb within cycle T0 can be used to avoid the influence of brief pulse interference (glitch) on the judgment. The charging current Ich and voltage Vb of the first two cycles of cycle T2 (i.e., cycle T1 and cycle T0) are both normal values. Subtracting the average voltage Vb of cycle T0 from the average voltage Vb of cycle T1 will make the voltage difference ΔVb of cycle T2 equivalent to 0. The logic judgment unit 34 will determine that the voltage difference ΔVb is less than the voltage threshold Vth, and the current path control unit 36 will continuously send a high-level control signal S1 to continuously keep the current path switch 20 on.
[0041] During cycle T3, a short-circuit current occurs, increasing the charging current Ich and consequently raising the voltage Vb. The logic unit 34 continuously calculates the difference ΔVb between the average voltage values of the previous two cycles. At this time, the voltage difference ΔVb resulting from subtracting the average voltage value of Vb in cycle T1 from the average voltage value of Vb in cycle T2 is still equivalent to 0. The logic unit 34 determines that the voltage difference ΔVb is still less than the voltage threshold Vth, therefore the current path control unit 36 continues to issue a high-level control signal S1. At this time, the current path switch 20 remains on.
[0042] In cycle T4, the logic judgment unit 34 determines that the voltage difference between the average voltage Vb of cycle T3 and the average voltage Vb of cycle T2 (i.e., the voltage difference ΔVb between the previous two cycles) is high and greater than the voltage threshold Vth. At this time, the current path control unit 36 sends a low-level control signal S1 to cut off the current path switch 20 to interrupt the charging current Ich, preventing excessive current from damaging the battery pack 100, thus protecting the battery pack 100. In cycle T4, the current path switch 20 is off, the charging current Ich is essentially 0 (the flow rate of the charging current Ich in cycle T4 is lower than that in cycles T0 to T2), and the voltage Vb drops back to a low level.
[0043] In cycle T5, logic unit 34 determines that the voltage difference (ΔVb) between the average voltage Vb of cycle T4 and the average voltage Vb of cycle T3 (the voltage difference ΔVb of the previous two cycles) has dropped to a negative value, which is less than the voltage threshold Vth. At this time, current path control unit 36 sends a high-level control signal S1 to reactivate current path switch 20, restoring the charging current Ich to the level before current path switch 20 was deactivated. In cycle T5, current path switch 20 is activated, and the charging current Ich returns to the normal flow rate of cycles T0 to T2, with voltage Vb at a normal level. It is important to note that logic unit 34 continuously calculates the difference ΔVb between the average voltages of the previous two cycles, and this voltage difference ΔVb remains negative until the end of cycle T5. The operation mode for the remaining cycles follows the same pattern.
[0044] Figure 4This is a schematic diagram of the discharge of the battery pack 100 in this embodiment. When the battery pack 100 discharges, the discharge current Idsg flows from the negative terminal P- to the positive terminal P+. Normally, the signal detection unit 32 can detect the voltage across the current sensing resistor 60 to detect the short-circuit current. The maximum instantaneous value of the short-circuit current can be several times the rated current, which may damage electronic components and cause malfunctions. However, when the current sensing resistor 60 malfunctions, the voltage across the current sensing resistor 60 is detected to be 0. At this time, the current monitoring system 30 can replace the current sensing resistor 60 to monitor the discharge current in the current path and detect whether a short-circuit current has occurred. The current path control unit 36 can issue a control signal S1 to control the current path switch 20 based on the detection result. In addition, the signal detection unit 32 can set the measured voltage signal to be the measured value of the highest cell voltage to ground (Vb = VCn - VSS), hereinafter referred to as voltage Vb.
[0045] Figure 5 for Figure 4 The example illustrates the signal diagram of battery pack 100 during discharge. During discharge, battery pack 100 operates in a normal discharge state from period T0 to T2. Each period is on the order of nanoseconds to picoseconds. ΔVb within each period is the difference between the average values of voltage Vb from the previous two periods. Taking period T2 as an example, the discharge current Idsg is at normal flow rate, and the voltage Vb is at normal level. The logic judgment unit 34 calculates the difference ΔVb between the average values of voltage from the two periods preceding period T2 (ΔVb = Vb). T0 -Vb T1 (i.e., the calculated value mentioned above). Vb T1 It can be the average value of the voltage Vb within period T1, Vb T0 This can be the average value of the voltage Vb within period T0 to avoid the influence of brief pulse interference on the judgment. Special note: Figure 5 and Figure 3 The calculation method for ΔVb in the embodiment is the opposite; Figure 5 In the example, ΔVb=Vb T-2 -Vb T-1 , Figure 3 In the example, ΔVb=Vb T-1 -Vb T-2 The discharge current Idsg and voltage Vb of the first two cycles of period T2 (i.e., periods T0 and T1) are both within normal ranges. The average voltage Vb of period T0 minus the average voltage Vb of period T1 will make the voltage difference ΔVb generated in period T2 equivalent to 0. The logic judgment unit 34 will determine that the voltage difference ΔVb is less than the voltage threshold Vth, and the current path control unit 36 will continuously send a high-level control signal S1 to turn on the current path switch 20.
[0046] During cycle T3, a short-circuit current occurs, increasing the discharge current Idsg and causing a decrease in voltage Vb. The logic unit 34 continuously calculates the difference ΔVb between the average voltage values of the previous two cycles. At this time, the voltage difference ΔVb resulting from subtracting the average voltage value of Vb in cycle T2 from the average voltage value of Vb in cycle T1 is still equivalent to 0. The logic unit 34 determines that the voltage difference ΔVb is still less than the voltage threshold Vth, therefore the current path control unit 36 continues to issue a high-level control signal S1. At this time, the current path switch 20 remains on.
[0047] In cycle T4, the logic judgment unit 34 determines that the voltage difference between the average voltage Vb of cycle T2 and the average voltage Vb of cycle T3 (i.e., the voltage difference ΔVb between the previous two cycles) is high and greater than the voltage threshold Vth. At this time, the current path control unit 36 sends a low-level control signal S1 to cut off the current path switch 20 to interrupt the discharge current Idsg, preventing excessive current from damaging the battery pack 100, thus protecting the battery pack 100. In cycle T4, the current path switch 20 is off, the discharge current Idsg is essentially 0 (the discharge current Idsg in cycle T4 is lower than the discharge current from cycle T0 to T2), and the voltage Vb rises back to high.
[0048] In cycle T5, logic unit 34 determines that the voltage difference (ΔVb) between the average voltage Vb of cycle T3 and the average voltage Vb of cycle T4 has dropped to a negative value, less than the voltage threshold Vth. At this time, current path control unit 36 sends a high-level control signal S1 to reactivate current path switch 20, restoring the discharge current Idsg to its level before current path switch 20 was deactivated. In cycle T5, current path switch 20 is activated, and the discharge current Idsg returns to the normal flow rate of cycles T0 to T2, with voltage Vb at a normal level. It is important to note that logic unit 34 continuously calculates the difference ΔVb between the average voltages of the previous two cycles, and this voltage difference ΔVb remains negative until the end of cycle T5. The operating mode for the remaining cycles follows the same principle.
[0049] Figure 6This is a schematic diagram of the discharge of battery pack 100 according to another embodiment. When battery pack 100 discharges, the discharge current Idsg flows from the negative terminal P- to the positive terminal P+. Normally, signal detection unit 32 can detect the voltage across current sensing resistor 60 to detect short-circuit current. The maximum instantaneous value of short-circuit current can be several times the rated current, which may damage electronic components and cause malfunction. However, when current sensing resistor 60 malfunctions, the voltage across current sensing resistor 60 is detected to be 0. At this time, current monitoring system 30 can replace current sensing resistor 60 to monitor the discharge current in the current path and detect whether a short-circuit current has occurred. Current path control unit 36 can issue control signal S1 to control current path switch 20 according to the detection result. In addition, signal detection unit 32 can set the measured voltage signal to be the measured value of the highest cell voltage across the intermediate voltage of the current path (Vb = VCn - Vpack), hereinafter referred to as voltage Vb. In addition, voltage Vpack represents the intermediate voltage of the current path.
[0050] Figure 7 for Figure 6 The example illustrates the signal diagram of battery pack 100 during discharge. During discharge, battery pack 100 operates in a normal discharge state from period T0 to T2. Each period is on the order of nanoseconds to picoseconds. ΔVb within each period is the difference between the average values of voltage Vb from the previous two periods. Taking period T2 as an example, the discharge current Idsg is at normal flow rate, and the voltage Vb is at normal level. The logic judgment unit 34 calculates the difference ΔVb between the average values of voltage from the two periods preceding period T2 (ΔVb = Vb1 - Vb). T0 (i.e., the calculated value mentioned above). Special note: Vb T1 It can be the average value of the voltage Vb within period T1, Vb T0 The average voltage Vb within period T0 can be used to avoid the influence of brief pulse interference on the judgment. The discharge current Idsg and voltage Vb of the first two periods of period T2 (i.e., period T0 and period T1) are both normal values. The average voltage Vb of period T1 minus the average voltage Vb of period T0 will make the voltage difference ΔVb generated in period T2 equivalent to 0. The logic judgment unit 34 will determine that the voltage difference ΔVb is less than the voltage threshold Vth, and the current path control unit 36 will continuously send a high-level control signal S1 to continuously keep the current path switch 20 on.
[0051] During cycle T3, a short-circuit current occurs, increasing the discharge current Idsg and consequently raising the voltage Vb. The logic unit 34 continuously calculates the difference ΔVb between the average voltage values of the previous two cycles. At this time, the voltage difference ΔVb resulting from subtracting the average voltage value of Vb from the average voltage value of Vb in cycle T1 is still equivalent to 0. The logic unit 34 determines that the voltage difference ΔVb is still less than the voltage threshold Vth, therefore the current path control unit 36 continues to issue a high-level control signal S1. At this time, the current path switch 20 remains on.
[0052] In cycle T4, logic unit 34 determines that the voltage difference between the average voltage Vb of cycle T3 and the average voltage Vb of cycle T2 (i.e., the difference ΔVb between the average voltages of the previous two cycles) is high and greater than the voltage threshold Vth. At this time, the current path control unit 36 sends a low-level control signal S1 to cut off the current path switch 20 to interrupt the discharge current Idsg, preventing excessive current from damaging the battery pack 100, thus protecting the battery pack 100. In cycle T4, the current path switch 20 is off, the discharge current Idsg is essentially 0 (the discharge current Idsg in cycle T4 is lower than the discharge current from cycle T0 to T2), and the voltage Vb rises back to high.
[0053] In cycle T5, logic unit 34 determines that the voltage difference (ΔVb, the difference between the average voltages of the previous two cycles) generated by subtracting the average voltage of the previous cycle Vb from the average voltage of the previous cycle T3 has dropped to a negative value, which is less than the voltage threshold Vth. At this time, current path control unit 36 sends a high-level control signal S1 to reactivate current path switch 20, restoring the discharge current Idsg to the level before current path switch 20 was deactivated. In cycle T5, current path switch 20 is activated, and the discharge current Idsg returns to the normal flow rate of cycles T0 to T2, with voltage Vb at a normal level. It is important to note that logic unit 34 continuously calculates the difference ΔVb between the average voltages of the previous two cycles, and this voltage difference ΔVb remains negative until the end of cycle T5. The operation mode for the remaining cycles follows the same pattern.
[0054] Figure 8 for Figure 1 A flowchart of a current monitoring method 800 for a battery pack 100. The current monitoring method 800 includes the following steps:
[0055] S802: Signal detection unit 32 detects the voltage signal at the positive terminal of cell 10 and / or battery pack 100;
[0056] S804: Logic judgment unit 34 generates a calculated value of the voltage signal and generates a logic signal based on the calculated value; and
[0057] S806: The current path control unit 36 sends a control signal S1 to control the current path switch 20 based on the logic signal.
[0058] The details of the current monitoring method 800 have been described above and will not be discussed again here.
[0059] In summary, the battery pack and its current monitoring method according to the various embodiments of the present invention can use a current monitoring system to monitor the charging or discharging current in the current path when the current sensing resistor malfunctions, and detect whether a short-circuit current has occurred. Furthermore, the current path control unit can issue a control signal based on the detection results to control the current path switch, preventing excessive current from damaging the battery pack and thus achieving the function of protecting the battery pack.
[0060] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall be within the scope of the present invention.
Claims
1. A battery pack, comprising: A set of battery cells; A current path switch is coupled to this group of cells; A current sensing resistor is coupled between the negative terminal of the cell group and the battery pack to measure the current flowing through the current sensing resistor. and A current monitoring system, comprising: A signal detection unit, coupled to the positive terminal of the group of cells and / or the battery pack, is used to detect at least one voltage signal at the positive terminal of the group of cells and / or the battery pack when the current detection resistor experiences a short circuit abnormality. A logic judgment unit, coupled to the signal detection unit, is used to generate a calculated value of the voltage signal of the at least one voltage signal and generate a logic signal based on the calculated value. and A current path control unit, coupled to the logic judgment unit and the current path switch, is used to control the current path switch according to the logic signal.
2. The battery pack of claim 1, wherein the calculated value of the voltage signal is the difference between the average value of the voltage signal over a first unit time and the average value of the voltage signal over a second unit time.
3. The battery pack as claimed in claim 2, wherein when the logic judgment unit determines that the difference is higher than the threshold, the current path control unit turns off the current path switch.
4. The battery pack as claimed in claim 2, wherein when the logic judgment unit determines that the difference is lower than a threshold, the current path control unit turns on the current path switch.
5. The battery pack as claimed in claim 1, wherein the voltage signal is the highest voltage of the cells in the pack.
6. The battery pack of claim 1, wherein the voltage signal is the voltage of the positive terminal of the battery pack.
7. The battery pack of claim 1, wherein the voltage signal is the voltage difference between the highest voltage terminal of the battery cell and the positive terminal of the battery pack.
8. The battery pack of claim 1, wherein the battery pack comprises a plurality of cells connected in series.
9. The battery pack of claim 1, wherein each cell in the battery pack is coupled to the signal detection unit.
10. A current monitoring method for a battery pack, the battery pack comprising a group of battery cells, a current sensing resistor, a current path switch, and a current monitoring system, the current monitoring system comprising a signal detection unit, a logic judgment unit, and a current path control unit, the current sensing resistor being coupled between the group of battery cells and the negative terminal of the battery pack, the current path switch being coupled to the group of battery cells, the signal detection unit being coupled to the positive terminal of the group of battery cells and / or the battery pack, the logic judgment unit being coupled to the signal detection unit, and the current path control unit being coupled to the logic judgment unit and the current path switch, the method comprising: This current sensing resistor measures the current flowing through it; When a short circuit occurs in the current sensing resistor, the signal detection unit detects at least one voltage signal at the positive terminal of the cell group and / or the battery pack. The logic judgment unit generates a calculated value of the voltage signal of the at least one voltage signal and generates a logic signal based on the calculated value; and The current path control unit controls the current path switch according to the logic signal.
11. The current monitoring method of claim 10, wherein the calculated value of the voltage signal is the difference between the average value of the voltage signal in a first unit time and the average value of the voltage signal in a second unit time.
12. The current monitoring method as described in claim 11, wherein when the logic judgment unit determines that the difference is higher than a threshold, the current path control unit turns off the current path switch.
13. The current monitoring method as described in claim 11, wherein when the logic judgment unit determines that the difference is lower than a threshold, the current path control unit turns on the current path switch.
14. The current monitoring method as described in claim 10, wherein the voltage signal is the highest voltage of the group of cells.
15. The current monitoring method of claim 10, wherein the voltage signal is the voltage of the positive terminal of the battery pack.
16. The current monitoring method as described in claim 10, wherein the voltage signal is the voltage difference between the highest voltage terminal of the battery cell and the positive terminal of the battery pack.