TWI830546B - Battery pack and its current monitoring method - Google Patents

Abstract

A battery pack includes a set of battery cells, a current path switch and a current monitoring system. The current monitoring system includes a signal measurement unit, a logic unit and a current path control unit. The current path switch is coupled to the set of battery cells. The signal measurement unit is coupled to the set of battery cells and/or a positive terminal of the battery pack for detecting at least one impedance signal of the set of battery cells and/or the positive terminal of the battery pack. The logic unit is coupled to the signal measurement unit, for generating a calculation value from the impedance signal and generating a logic signal according to the calculation value. The current path control unit is coupled to the logic unit and the current path switch, for controlling the current path switch according to the logic signal.

Description

Battery pack and current monitoring method

The present invention relates to a battery pack, in particular to a battery pack and its current monitoring method.

Rechargeable battery packs are widely used in the consumer electronics market, covering mobile phones, laptops, game consoles, digital cameras, portable devices, etc. A battery pack refers to a finished product that is assembled by welding battery cells, protective plates, battery wires, battery nickel sheets, battery accessories, battery boxes, battery membranes, etc. In the field of consumer electronics, battery pack technology and market have matured and are growing. The smaller the internal resistance of the battery pack, the higher the output power. The output power of a battery refers to the battery's ability to output energy per unit time, calculated based on the discharge current and discharge voltage. At rated voltage, the output power of the battery increases with the increase of electrode surface area and operating temperature, and also decreases with the decrease of temperature.

A short circuit refers to the situation when two points with different potentials in a normal circuit are directly connected incorrectly or connected by a conductor with very small impedance (or resistance). The short-circuit current intensity is very large, and its current value is much greater than the rated current (ideal current when the electrical appliance is working), which often damages the rechargeable battery pack and even causes a fire. Generally, rechargeable battery packs are equipped with current detection resistors. According to Ohm's law, when current flows through a resistor, a voltage difference will occur across the resistor. Divide the voltage difference by the resistance value to get the current value through the resistor. If a resistor with a larger resistance is used to obtain a larger voltage difference, it is easy to cause the resistor to overheat. Therefore, a resistor with the smallest possible resistance should be used for detection. When a circuit failure causes the current intensity to exceed the normal range, the circuit's protection mechanism can detect the abnormal current through the voltage at both ends of the current detection resistor, and can cut off the current path and stop circuit operation to ensure safety. However, when the current detection resistor itself has a short circuit abnormality, it is impossible to monitor the voltage across the resistor to determine the current.

The embodiment provides a battery pack, including a set of 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 cells, and the signal detection unit is coupled to the set of cells and/or the positive terminal of the battery pack for detecting the set of cells and/or the positive terminal of the battery pack. at least one voltage signal. The logic judgment unit is coupled to the signal detection unit and used to generate a calculated value of one of the at least one voltage signal and generate a logic signal according to the calculated value. The current path control unit is coupled to the logic judgment unit and the current path switch, and is used to control the current path switch according to the logic signal.

The embodiment provides a current monitoring method for a battery pack. The battery pack contains a set of cells, current path switches and current monitoring systems. 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 group of cells, the signal detection unit is coupled to the group of cells and/or the positive terminal of the battery pack, the logic judgment unit is coupled to the signal detection unit, and the current path control The 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 of the group of cells and/or the positive terminal of the battery pack, and the logic judgment unit generating a calculated value of one of the at least one voltage signal and based on the calculation The value generates a logic signal, and the current path control unit controls the current path switch according to the logic signal.

100:battery pack

10:Battery core

20:Current path switch

30:Current monitoring system

32: Signal detection unit

34: Logical judgment unit

36:Current path control unit

60:Current detection resistor

P+: positive terminal of battery pack

P-: negative terminal of battery pack

VCn, VC1, VSS: cell voltage

Vpack: current path intermediate voltage

Vb: voltage

ΔVb: voltage difference

Vth: voltage threshold

S1: control signal

Ich: charging current

Idsg: discharge current

T0~T5: period

800:Method

S802~S806: steps

Figure 1 is a schematic diagram of a battery pack according to an embodiment of the present invention.

Figure 2 is a schematic diagram of charging the battery pack in Figure 1.

Figure 3 shows the charging signal diagram of the battery pack in Figure 2.

Figure 4 is a schematic diagram of the discharge of the battery pack in Figure 1.

Figure 5 is a signal diagram of the discharge of the battery pack in Figure 4.

Figure 6 is a schematic diagram of another discharge of the battery pack in Figure 1.

Figure 7 is a signal diagram of the discharge of the battery pack in Figure 6.

Figure 8 is a flow chart of the current monitoring method of the battery pack in Figure 1.

What follows is intended to illustrate the principles of the invention but is not intended to limit the scope of the invention. The term "substantially" as used below includes the numerical value as well as the specific value determined by one of ordinary skill in the art within an acceptable deviation range, taking into account measurement problems and errors. For example, "substantially" can mean within one or more standard deviations. In addition, due to manufacturing process variations of electronic devices, the term "same" may also be interpreted as "approximately". In particular, the following invention content provides multiple different embodiments or examples to implement applications with different characteristics. Specific examples of components and arrangements are described below to simplify the disclosure. These descriptions are intended to provide examples only and are not intended to limit the scope of the invention. In addition, the present invention may use repeated reference numbers and/or letters in various examples. Repeated reference numbers and/or letters are used for simplicity and clarity of expression, and the numbers and/or letters themselves do not necessarily imply a relationship between the various embodiments and/or configurations discussed. Furthermore, in various embodiments of the present invention, the connection and/or coupling relationship formed between the characteristic components may include embodiments formed in the form of direct contact, and may also include those formed between the two. Embodiments formed indirectly by inserting additional features.

Figure 1 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 . Current path switch 20 coupler Connected to battery core 10. The signal detection unit 32 is coupled to the positive terminal P+ of the battery cell 10 and the battery pack, and is used to detect at least one voltage signal of the positive terminal P+ of the battery cell 10 and/or the battery pack 100 . That is to say, the signal detection unit 32 can detect the voltage signal of the battery cell 10 and can 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 at least one voltage signal and generate a logic signal based on the calculated value. Details of the calculated values are detailed 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. The current detection resistor 60 is coupled between the cell 10 and the negative terminal P- of the battery pack 100 , and both ends of the current detection resistor 60 are coupled to the signal detection unit 32 respectively. The negative terminal P- can be grounded. In addition, the battery cell 10 may be composed of a plurality of series-connected battery cells. Each cell in the cell 10 can be coupled to the signal detection unit 32 respectively, and each cell can measure a corresponding voltage, such as VCn, VC1...and so on. The voltage VCn represents the highest cell voltage of the cell 10, and VSS represents the ground voltage of the cell 10.

In practical applications, the signal detection unit 32 may be an analog-to-digital converter (ADC), the logic judgment unit 34 may be an arithmetic logic unit (ALU), and the current path control unit 36 may be Any circuit that generates a switch signal. The current path switch 20 may be a transistor, and is not limited to a single transistor, but may be a plurality of transistors connected in parallel. For example, two N-type metal oxide semiconductor field effect transistors (N-Metal-Oxide-Semiconductor, NMOS) are respectively provided in the charging path and the discharging path to control the charging and discharging conditions respectively. The above components are only examples, and other equal circuit components should fall within the scope of the present invention.

Figure 2 is a schematic diagram of charging the battery pack 100 in Figure 1 . When the battery pack 100 is charging, the charging current Ich flows from the positive terminal P+ of the battery pack to the negative terminal P-. Normally, the signal detection unit 32 can detect the voltage across the current detection resistor 60 to detect the short-circuit current. The maximum instantaneous value of short-circuit current can reach the rated current Several times the current may damage electronic components and cause malfunctions. However, when an abnormality occurs in the current detection resistor 60 , it is detected that the voltage across the current detection resistor 60 is 0. At this time, the current monitoring system 30 can replace the current detection resistor 60 to monitor the charging current on the current path and detect whether a short-circuit current occurs. The current path control unit 36 can send the control signal S1 according to the detection result to control the current path switch 20 . In addition, the signal detection unit 32 can set the measured voltage signal to the measured value of the highest cell voltage with respect to ground (Vb=VCn-VSS), hereinafter referred to as voltage Vb.

Figure 3 is a charging signal diagram of the battery pack 100 in Figure 2 . When the battery pack 100 is charging, the battery pack 100 is in a normal charging state during periods T0, T1, and T2. Each cycle can be on the order of nanosecond to picosecond. ΔVb in each cycle is the difference between the average values of the voltage Vb in the previous two cycles. Taking cycle T2 as an example, the charging current Ich is a normal flow rate and the voltage Vb is a normal level. The logic judgment unit 34 calculates the difference ΔVb between the average voltages of the two periods before period T2 (ΔVb=Vb _T1 -Vb _T0 , which is the above-mentioned calculated value). In particular, Vb _T1 can be the average value of the voltage Vb in the period T1, and Vb _T0 can be the average value of the voltage Vb in the period T0 to avoid short pulse interference (glitch) from affecting the judgment. The charging current Ich and voltage Vb of the first two periods of period T2 (ie, period T1 and period T0) are both normal values. The average voltage Vb of the period T1 minus the average voltage Vb of the period T0 will make the voltage difference ΔVb of the period T2 equal to 0. The logic judgment unit 34 determines that the voltage difference ΔVb is less than the voltage threshold Vth, and the current path control unit 36 continues to send the high-level control signal S1 to continue to turn on the current path switch 20 .

In period T3, a short-circuit current occurs, and the flow rate of the charging current Ich increases, causing the voltage Vb to also increase. The logic judgment unit 34 continues to calculate the difference ΔVb between the average voltages of the previous two cycles. At this time, the voltage difference ΔVb generated by subtracting the average voltage Vb of period T1 from the average voltage Vb of period T2 is still equivalent to 0. The logic judgment unit 34 judges that the voltage difference ΔVb is still less than the voltage threshold Vth, so the current path control unit 36 still sends the high-level control signal S1. At this time, the current path switch 20 continues to be turned on.

In the period T4, the logic judgment unit 34 determines that the voltage difference generated by subtracting the average voltage Vb of the period T2 from the average voltage Vb of the period T2 (i.e., the voltage difference ΔVb of the first two periods) is a high level. And is greater than the voltage threshold Vth. At this time, the low-level control signal S1 sent by the current path control unit 36 turns off the current path switch 20 to cut off the charging current Ich to prevent excessive current from damaging the battery pack 100, thereby achieving the function of protecting the battery pack 100. In the period T4, the current path switch 20 is turned off, the charging current Ich is substantially 0 (the flow rate of the charging current Ich in the period T4 is lower than the flow rate in the periods T0 to T2), and the voltage Vb drops back to a low level.

In the period T5, the logic judgment unit 34 will determine that the voltage difference generated by the average voltage Vb of the period T4 minus the average voltage Vb of the period T3 (the voltage difference ΔVb of the first two periods) drops to a negative value, less than Voltage threshold Vth. At this time, the current path control unit 36 sends a high-level control signal S1 to restore the current path switch 20 to turn on, causing the charging current Ich to return to the level before the current path switch 20 is turned off. In the period T5, the current path switch 20 is turned on, the charging current Ich returns to the normal flow rate in the period T0 to T2, and the voltage Vb is at a normal level. Specifically, the logic judgment unit 34 continues to calculate the difference ΔVb between the average voltages of the previous two periods, and the voltage difference ΔVb will remain negative until the end of period T5. The operating mode for the remaining cycles can be deduced in this way.

Figure 4 is a schematic diagram of the discharge of the battery pack 100 according to the embodiment. When the battery pack 100 is discharged, the discharge current Idsg flows from the negative terminal P- of the battery pack to the positive terminal P+. Normally, the signal detection unit 32 can detect the voltage across the current detection resistor 60 to detect the short-circuit current. The maximum instantaneous value of the short-circuit current can reach several times the rated current, which may damage electronic components and cause malfunctions. However, when an abnormality occurs in the current detection resistor 60 , it is detected that the voltage across the current detection resistor 60 is 0. At this time, the current monitoring system 30 can replace the current detection resistor 60 to monitor the discharge current on the current path and detect whether a short-circuit current occurs. Current path control The control unit 36 can send the control signal S1 to control the current path switch 20 according to the detection result. In addition, the signal detection unit 32 can set the measured voltage signal to the measured value of the highest cell voltage with respect to ground (Vb=VCn-VSS), hereinafter referred to as voltage Vb.

Figure 5 is a signal diagram of the discharge of the battery pack 100 in the embodiment of Figure 4. When the battery pack 100 is discharging, the battery pack 100 is in a normal discharge state during periods T0 to T2. Each cycle can be on the order of nanosecond to picosecond. ΔVb in each cycle is the difference between the average values of the voltage Vb in the previous two cycles. Taking cycle T2 as an example, the discharge current Idsg is the normal flow rate and the voltage Vb is the normal level. The logic judgment unit 34 calculates the difference ΔVb between the average voltages of the two periods before period T2 (ΔVb=Vb _T0 -Vb _T1 , which is the above-mentioned calculated value). Vb _T1 can be the average value of voltage Vb in period T1, and Vb _T0 can be the average value of voltage Vb in period T0 to avoid short-term pulse interference from affecting judgment. In particular, the calculation method of ΔVb in the embodiment in Figure 5 is opposite to that in the embodiment in Figure 3; ΔVb=Vb _T-2 -Vb _T-1 in the embodiment in Figure 5, and ΔVb=Vb _T-1 - in the embodiment in Figure 3. Vb _T-2 . The discharge current Idsg and voltage Vb of the first two periods of period T2 (ie, period T0 and period T1) are both normal values. The average value of voltage Vb of period T0 minus the average value of voltage Vb of period T1 will cause period T2 to occur. The voltage difference ΔVb is equivalent to 0. The logic judgment unit 34 determines that the voltage difference ΔVb is less than the voltage threshold Vth, and the current path control unit 36 continues to send a high-level control signal S1 to turn on the current path switch 20 .

In period T3, a short-circuit current occurs, and the flow rate of the discharge current Idsg increases, causing the voltage Vb to also decrease. The logic judgment unit 34 continues to calculate the difference ΔVb between the average voltages of the previous two cycles. At this time, the voltage difference ΔVb generated by subtracting the average voltage Vb of period T2 from the average voltage Vb of period T1 is still equivalent to 0. The logic judgment unit 34 judges that the voltage difference ΔVb is still less than the voltage threshold Vth, so the current path control unit 36 still sends the high-level control signal S1. At this time, the current path switch 20 continues to be turned on.

In period T4, the logic judgment unit 34 determines that the voltage difference generated by subtracting the average voltage Vb of period T3 from the average voltage Vb of period T3 (i.e., the voltage difference ΔVb of the first two periods) is a high level. And is greater than the voltage threshold Vth. At this time, the low-level control signal S1 sent by the current path control unit 36 turns off the current path switch 20 to cut off the discharge current Idsg to prevent excessive current from damaging the battery pack 100, thereby achieving the function of protecting the battery pack 100. In the period T4, the current path switch 20 is turned off, the discharge current Idsg is substantially 0 (the flow rate of the discharge current Idsg in the period T4 is lower than the flow rate in the periods T0 to T2), and the voltage Vb rises back to a high level.

In the period T5, the logic judgment unit 34 will determine that the voltage difference generated by the average voltage Vb of the period T3 minus the average voltage Vb of the period T4 (the voltage difference ΔVb of the first two periods) drops to a negative value, less than Voltage threshold Vth. At this time, the current path control unit 36 sends a high-level control signal S1 to restore the conduction of the current path switch 20, causing the discharge current Idsg to return to the level before the current path switch 20 is turned off. In the period T5, the current path switch 20 is turned on, the discharge current Idsg returns to the normal flow rate in the period T0 to T2, and the voltage Vb is at a normal level. Specifically, the logic judgment unit 34 continues to calculate the difference ΔVb between the average voltages of the previous two periods, and the voltage difference ΔVb will remain negative until the end of period T5. The operating mode for the remaining cycles can be deduced in this way.

FIG. 6 is a schematic diagram of the discharge of the battery pack 100 in another embodiment. When the battery pack 100 is discharged, the discharge current Idsg flows from the negative terminal P- of the battery pack to the positive terminal P+. Normally, the signal detection unit 32 can detect the voltage across the current detection resistor 60 to detect the short-circuit current. The maximum instantaneous value of the short-circuit current can reach several times the rated current, which may damage electronic components and cause malfunctions. However, when an abnormality occurs in the current detection resistor 60 , it is detected that the voltage across the current detection resistor 60 is 0. At this time, the current monitoring system 30 can replace the current detection resistor 60 to monitor the discharge current on the current path and detect whether a short-circuit current occurs. The current path control unit 36 can send the control signal S1 according to the detection result to control the current path switch 20 . Other In addition, the signal detection unit 32 can set the measured voltage signal to be the measured value of the highest cell voltage versus the middle cross-voltage of the current path (Vb=VCn-Vpack), hereinafter referred to as the voltage Vb. In addition, the voltage Vpack represents the current path intermediate voltage.

Figure 7 is a signal diagram of the discharge of the battery pack 100 in the embodiment of Figure 6. When the battery pack 100 is discharging, the battery pack 100 is in a normal discharge state during periods T0 to T2. Each cycle can be on the order of nanosecond to picosecond. ΔVb in each cycle is the difference between the average values of the voltage Vb in the previous two cycles. Taking cycle T2 as an example, the discharge current Idsg is the normal flow rate and the voltage Vb is the normal level. The logic judgment unit 34 will calculate the difference ΔVb between the average voltages of the two periods before period T2 (ΔVb=Vb ₁ -Vb _T0 , which is the above-mentioned calculated value). In particular, Vb _T1 can be the average value of voltage Vb in period T1, and Vb _T0 can be the average value of voltage Vb in period T0 to avoid short-term pulse interference from affecting judgment. The discharge current Idsg and voltage Vb of the first two periods of period T2 (ie, period T0 and period T1) are both normal values. The average value of voltage Vb of period T1 minus the average value of voltage Vb of period T0 will cause period T2 to occur. The voltage difference ΔVb is equivalent to 0. The logic judgment unit 34 determines that the voltage difference ΔVb is less than the voltage threshold Vth, and the current path control unit 36 continues to send the high-level control signal S1 to continue to turn on the current path switch 20 .

In period T3, a short-circuit current occurs, and the flow rate of the discharge current Idsg increases, causing the voltage Vb to also increase. The logic judgment unit 34 continues to calculate the difference ΔVb between the average values of the voltages of the previous two cycles. At this time, the voltage difference ΔVb generated by subtracting the average voltage Vb of period T1 from the average voltage Vb of period T2 is still equivalent to 0. The logic judgment unit 34 judges that the voltage difference ΔVb is still less than the voltage threshold Vth, so the current path control unit 36 still sends the high-level control signal S1. At this time, the current path switch 20 continues to be turned on.

In the period T4, the logic judgment unit 34 will determine the voltage difference generated by subtracting the average value of the voltage Vb of the period T2 from the average value of the voltage Vb of the period T3 (that is, the difference between the average values of the voltages of the previous two periods). ΔVb) is a high level and is greater than the voltage threshold Vth. At this time, the low-level control signal S1 sent by the current path control unit 36 turns off the current path switch 20 to cut off the discharge current Idsg to prevent excessive current from damaging the battery pack 100, thereby achieving the function of protecting the battery pack 100. In the period T4, the current path switch 20 is turned off, the discharge current Idsg is substantially 0 (the flow rate of the discharge current Idsg in the period T4 is lower than the flow rate in the periods T0 to T2), and the voltage Vb rises back to a high level.

In the period T5, the logic judgment unit 34 will determine that the voltage difference generated by subtracting the average voltage Vb of the period T3 from the average voltage Vb of the period T4 (the difference ΔVb between the average voltages of the previous two periods) decreases to Negative value, less than the voltage threshold Vth. At this time, the current path control unit 36 sends a high-level control signal S1 to restore the conduction of the current path switch 20, causing the discharge current Idsg to return to the level before the current path switch 20 is turned off. In the period T5, the current path switch 20 is turned on, the discharge current Idsg returns to the normal flow rate in the period T0 to T2, and the voltage Vb is at a normal level. Specifically, the logic judgment unit 34 continues to calculate the difference ΔVb between the average voltages of the previous two periods, and the voltage difference ΔVb will remain negative until the end of period T5. The operating mode for the remaining cycles can be deduced in this way.

FIG. 8 is a flow chart of the current monitoring method 800 of the battery pack 100 in FIG. 1 . The current monitoring method 800 includes the following steps: S802: The signal detection unit 32 detects the voltage signal of the positive terminal of the cell 10 and/or the battery pack 100; S804: The logic judgment unit 34 generates a calculated value of the voltage signal and generates a logic signal according to the calculated value; And S806: the current path control unit 36 sends the control signal S1 according to the logic signal to control the current path switch 20.

The details of the current monitoring method 800 have been described above and will not be discussed further here.

In summary, the battery pack and its current monitoring method according to various embodiments of the present invention can use the current monitoring system to replace the current detection resistor to monitor the charging or discharging current on the current path when an abnormality occurs in the current detection resistor, and detect whether an abnormality occurs. short circuit current. Moreover, the current path control unit can send a control signal according to the detection result to control the current path switch to prevent excessive current from damaging the battery pack, thereby achieving the function of protecting the battery pack.

The above are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the patentable scope of the present invention shall fall within the scope of the present invention.

100:battery pack

10:Battery core

20:Current path switch

30:Current monitoring system

32: Signal detection unit

34: Logical judgment unit

36:Current path control unit

60:Current detection resistor

P+: positive terminal of battery pack

P-: negative terminal of battery pack

VCn, VC1, VSS: cell voltage

Claims (11)

A battery pack, including: a group of cells; a current path switch, coupled to the group of cells; a current monitoring system, including: a signal detection unit, coupled to the group of cells and/or a positive terminal of the battery pack, used to detect at least one voltage signal (impedance signal) of the battery cell and/or the positive terminal of the battery pack; a logic judgment unit coupled to the signal detection unit , used to generate a calculated value of one of the at least one voltage signal and generate a logic signal according to the calculated value; and a current path control unit coupled to the logic judgment unit and the current path switch, used to generate a logic signal according to the calculated value. The logic signal controls the current path switch; wherein: the calculated value of the voltage signal is the sum of an average value of the voltage signal in a first unit time and an average value of the voltage signal in a second unit time. a difference; when the logic judgment unit judges that the difference is higher than a threshold, the current path control unit turns off the current path switch; and when the logic judgment unit judges that the difference is lower than the threshold, the current The path control unit conducts the current path switch. The battery pack according to claim 1 further includes a current detection resistor coupled between the battery cell and a negative terminal of the battery pack, and both ends of the current detection resistor are coupled to the signal detection resistor respectively. unit. The battery pack as claimed in claim 1, wherein the voltage signal is a highest voltage of the cells of the set. The battery pack as claimed in claim 1, wherein the voltage signal is a voltage of the positive terminal of the battery pack. The battery pack as claimed in claim 1, wherein the voltage signal is a cross voltage between a highest voltage terminal of the battery cells and the positive terminal of the battery pack. The battery pack as claimed in claim 1, wherein the set of cells includes a plurality of cells connected in series. The battery pack according to claim 1, wherein each cell in the group of cells is coupled to the signal detection unit respectively. A current monitoring method for a battery pack. The battery pack includes a set of 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 group of cells, the signal detection unit is coupled to the group of cells and/or a positive terminal of the battery pack, the logic judgment unit is coupled to the signal detection unit, and the current path The control unit is coupled to the logic judgment unit and the current path switch. The method includes: the signal detection unit detects at least one voltage signal of the group of cells and/or the positive terminal of the battery pack; the logic judgment unit generates the A calculated value of the voltage signal of at least one voltage signal and generating a logic signal based on the calculated value, wherein the calculated value of the voltage signal is the voltage signal A difference between an average value of the voltage signal in a first unit time and an average value of the voltage signal in a second unit time; and the current path control unit controls the current path switch according to the logic signal, wherein when the When the logic judgment unit judges that the difference is higher than a threshold, the current path control unit turns off the current path switch, and when the logic judgment unit judges that the difference is lower than the threshold, the current path control unit turns on the current. Path switch. The current monitoring method as described in claim 8, wherein the voltage signal is a highest voltage of the group of cells. The current monitoring method of claim 8, wherein the voltage signal is a voltage of the positive terminal of the battery pack. The current monitoring method as described in claim 8, wherein the voltage signal is a cross-voltage between a highest voltage terminal of the group of cells and the positive terminal of the battery group.

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