Detection circuit and detection method for a battery pack

Abstract

The application discloses a detection circuit and a detection method for a battery pack. The battery pack comprises a plurality of batteries connected in series. The detection circuit comprises a plurality of detection units corresponding to the plurality of batteries one by one. Each detection unit comprises a capacitor, a first sampling resistor, a second sampling resistor and a switching unit. The first end of the first sampling resistor is connected to the first end of the battery corresponding to the detection unit, and the second end of the first sampling resistor is connected to a first sampling port. The first end of the second sampling resistor is connected to the second end of the battery corresponding to the detection unit, and the second end of the second sampling resistor is connected to a second sampling port. The switching unit is used for switching the working mode of the detection unit. An adjusting unit is used for adjusting the resistance value of the resistance between the battery corresponding to the detection unit and the sampling port according to the working mode of the detection unit. A measuring unit is used for measuring the first voltage difference and the second voltage difference between the sampling ports when the detection unit works in the first working mode and the second working mode respectively. Whether the battery corresponding to the detection unit is disconnected or whether the battery corresponding to the detection unit is short-circuited is judged according to the first voltage difference and the second voltage difference, so that the disconnection detection and the short-circuit detection of the battery pack are simultaneously performed.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to a detection circuit and detection method for battery packs. Background Technology

[0002] With the continuous development of new energy technologies, batteries have been applied to all aspects of people's lives. In battery applications, battery packs, as key components, are typically composed of multiple batteries connected in series and equipped with a battery management system (BMS). The BMS manages the battery during use to improve battery performance and safety. Overcharging and over-discharging are two key indicators for measuring battery performance and safety. When a battery is overcharged, the electrolyte inside the battery decomposes, causing the battery to swell and potentially leading to safety issues. When a battery is over-discharged, sulfates inside the battery crystallize, leading to a decrease in battery capacity and potentially causing short circuits.

[0003] Existing battery management systems use an AFE (analog front end) chip to monitor the battery pack's overvoltage, undervoltage, and overcurrent conditions and execute protective actions when these conditions occur. Due to variations in battery pack installation and usage scenarios, the sampling line between the battery cell and the AFE chip can become disconnected, leading to overcharging. Furthermore, leakage at the sampling port can cause over-discharging of the battery.

[0004] Figure 1 A schematic diagram of a first detection circuit according to the prior art is shown. The detection circuit 100 is used to detect whether the battery pack is disconnected. See also... Figure 1 The detection circuit 100 includes an amplifier (AFE) and resistors R1-R8. The battery pack includes batteries B4-B0 connected in series from top to bottom. The detection circuit 100 detects whether the sampling line between batteries B0-B4 and the AFE is broken by using the parallel resistors at the ports. Assuming that the sampling line between the common node of batteries B1 and B2 and the sampling port C2 of the AFE is broken, the sampling value of battery B2 will be 0, and the sampling value of battery B1 will be B1+B2. Therefore, the sampling value of the battery can be used to determine whether the sampling line is broken.

[0005] The detection circuit 100 needs to place fixed resistors alternately at the sampling port, which will cause power consumption differences between individual units. In order to reduce this difference, the resistance value of the fixed resistor is generally large (above MΩ). Although it can detect the case of complete disconnection, it may not be able to detect the case of poor contact (contact impedance in KΩ).

[0006] Figure 2 A schematic diagram of a second detection circuit according to the prior art is shown. The detection circuit 200 is used to detect whether the sampling line is broken. See also... Figure 2The detection circuit 200 includes an amplifier circuit (AFE), and the battery pack includes batteries B1-B6 connected in series from bottom to top. Batteries B1-B6 are connected to sampling ports C0-C6 of the AFE. The AFE includes a pull-up constant current source S1 and a pull-down constant current source S2. When detecting a break in the connection of batteries B1-B6, the pull-up constant current source S1 is first enabled, and the pull-down constant current source S2 is disabled. Then, sampling ports C0-C5 are sequentially traversed. If the sampling line between sampling port Cx and the battery is broken, the sampled value of sampling port Cx will reach its maximum value. Then, the pull-up constant current source S1 is disabled, and the pull-down constant current source S2 is enabled. Sampling ports C1-C6 are sequentially traversed. If the sampling line between sampling port Cx and the battery is broken, the sampled value of sampling port Cx will become 0. The breakage of the sampling line can be determined by these two sampling values.

[0007] The pull-up constant current source S1 and pull-down constant current source S2 of the detection circuit 200 are connected to V+ and V- respectively. Similarly, in order to reduce the power consumption difference between individual units, the value of the constant current source is usually small, generally 100uA. Therefore, it cannot detect the open circuit impedance below 100KΩ.

[0008] Figure 3 A schematic diagram of a third detection circuit according to the prior art is shown. The detection circuit 300 is used to detect whether the battery in the battery pack is leaking current. See also... Figure 3 When detecting whether battery Bn is leaking current, it is necessary to obtain the voltage difference VC(n) between sampling port Cn-1 and Cn, and the voltage difference VS(n) between equalization port Sn-1 and Sn. If there is a leakage current I1 to ground at sampling port Cn, and assuming the filter resistor of the sampling circuit is R, then:

[0009] VS(n) = I1*R + VC(n)

[0010] From this, we can deduce that:

[0011]

[0012] When VS(n)-VC(n) is detected to be greater than the set threshold, it can be determined that the sampling port Cn is leaking current.

[0013] The detection circuit 300 requires the use of an equalization pin. For an AFE without an independent equalization pin, leakage current detection cannot be directly achieved.

[0014] In summary, the detection circuits of existing battery management systems cannot detect breaks in sampling lines with low open-circuit impedance, and cannot perform leakage current detection when the AFE lacks an independent balancing pin. Furthermore, leakage current detection and open-circuit detection require two separate detection circuits. Therefore, a new detection circuit for battery packs is needed to address these issues. Summary of the Invention

[0015] In view of the above problems, the purpose of this invention is to provide a detection circuit and detection method for battery packs, so as to simultaneously detect open circuits and leakage current in battery packs.

[0016] According to one aspect of the present invention, a detection circuit for a battery pack is provided, the battery pack comprising a plurality of batteries connected in series, the detection circuit comprising a plurality of detection units corresponding one-to-one with the plurality of batteries, each detection unit comprising a first sampling resistor, a second sampling resistor, a capacitor, an adjustment unit, a switching unit, and a measurement unit, wherein a first end of the first sampling resistor is connected to a first end of the battery corresponding to the detection unit, and a second end of the first sampling resistor is connected to a first sampling port; a first end of the second sampling resistor is connected to a second end of the battery corresponding to the detection unit, and a second end of the second sampling resistor is connected to a second sampling port; the switching unit is used to switch the operating mode of the detection unit; the adjustment unit is used to adjust the resistance value between the battery corresponding to the detection unit and the sampling port according to the operating mode of the detection unit; the measurement unit is used to measure a first voltage difference between the first sampling port and the second sampling port when the detection unit operates in a first operating mode, and a second voltage difference between the first sampling port and the second sampling port when the detection unit operates in a second operating mode, and to determine whether the battery corresponding to the detection unit is disconnected and whether it is leaking current based on the first voltage difference and the second voltage difference.

[0017] Optionally, the measuring unit is also used to calculate the disconnection resistance when the battery corresponding to the detection unit is disconnected, and to calculate the leakage current when the battery corresponding to the detection unit is leaking.

[0018] Optionally, the switching unit includes a first resistor and a switch connected between the first sampling port and the second sampling port, and the operating mode of the detection unit is achieved by switching the switch on and off.

[0019] Optionally, the adjustment unit is connected in parallel with the second sampling resistor; the first end of the capacitor is connected to the second end of the first sampling resistor, and the second end of the capacitor is connected to the second end of the second sampling resistor.

[0020] Optionally, the adjustment unit includes a switching transistor and a second resistor connected sequentially between the first and second ends of the second sampling resistor. The control terminal of the switching transistor is connected to the second end of the second sampling resistor, wherein the switching transistor's on and off states are synchronized with the on and off states of the switch.

[0021] Optionally, the adjustment unit is connected in parallel with the first sampling resistor; the first end of the capacitor is connected to the second end of the first sampling resistor, and the second end of the capacitor is grounded.

[0022] Optionally, the adjustment unit includes a switching transistor and a third resistor connected sequentially between a first end and a second end of the first sampling resistor. The control terminal of the switching transistor is connected to the second end of the first sampling resistor, wherein the switching transistor's on and off states are synchronized with the on and off states of the switch.

[0023] Optionally, the switching unit includes a constant current source and a switch connected between the first sampling port and the second sampling port, and the operating mode of the detection unit is achieved by switching the switch on and off.

[0024] Optionally, the switching transistor includes two MOSFETs connected in sequence, wherein the MOSFETs are low-voltage MOSFETs.

[0025] According to another aspect of the present invention, a detection method for a battery pack is provided. The detection method is implemented using the detection circuit described above. The detection method includes switching the detection unit of the battery under test to a first operating mode and acquiring a first voltage difference between a first sampling port and a second sampling port in the first operating mode; switching the detection unit of the battery under test to a second operating mode and acquiring a second voltage difference between the first sampling port and the second sampling port in the second operating mode; determining whether the battery under test is leaking current and whether it is disconnected based on the first voltage difference and the second voltage difference; and calculating the disconnection resistance when the battery under test is disconnected and calculating the leakage current when the battery under test is leaking current.

[0026] The present invention provides a detection circuit and detection method for a battery pack. The detection circuit includes multiple detection units corresponding one-to-one with multiple batteries in the battery pack. Each detection unit includes a first sampling resistor, a second sampling resistor, a capacitor, an adjustment unit, a switching unit, and a measurement unit. The first end of the first sampling resistor is connected to the first end of the battery corresponding to the detection unit, and the second end of the first sampling resistor is connected to a first sampling port. The first end of the second sampling resistor is connected to the second end of the battery corresponding to the detection unit, and the second end of the second sampling resistor is connected to a second sampling port. When detecting the battery corresponding to the detection unit, it is only necessary to sample the first voltage difference between the first sampling port and the second sampling port when the detection unit is working in the first working mode, and the second voltage difference between the first sampling port and the second sampling port when the detection unit is working in the second working mode. The battery can be determined to be disconnected or leaking current based on the first voltage difference and the second voltage difference. This detection circuit can simultaneously detect disconnection and leakage of the battery, saving time and is not limited by the disconnection impedance or whether the AFE has a balancing pin. Attached Figure Description

[0027] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0028] Figure 1 A schematic diagram of a first detection circuit according to the prior art is shown;

[0029] Figure 2 A schematic diagram of a second detection circuit according to the prior art is shown;

[0030] Figure 3 A schematic diagram of a third detection circuit according to the prior art is shown;

[0031] Figure 4 A schematic diagram of the detection circuit according to a first embodiment of the present invention is shown;

[0032] Figure 5 It shows Figure 4 A schematic diagram of a detection unit in the detection circuit shown;

[0033] Figure 6 A schematic diagram of the detection circuit according to a second embodiment of the present invention is shown;

[0034] Figure 7 It shows Figure 6 A schematic diagram of a detection unit in the detection circuit shown;

[0035] Figure 8 A schematic diagram of the detection circuit according to a third embodiment of the present invention is shown. Detailed Implementation

[0036] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements or modules are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0037] It should be understood that, in the following description, "circuit" may include single or combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by the programmable circuit. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it may be directly coupled or connected to the other element, or there may be intermediate elements; the connection between elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0038] Furthermore, certain terms are used in this patent specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This patent specification and claims do not distinguish components based on differences in name, but rather on differences in function.

[0039] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] The detection circuit provided in this embodiment of the invention is used for a battery pack. Specifically, the detection circuit can perform open circuit detection and leakage detection on the battery pack. The battery pack includes n (n≥1) batteries connected in series, and the detection circuit includes multiple detection units corresponding to each battery. Each detection unit includes a first sampling resistor, a second sampling resistor, an adjustment unit, a capacitor, a switching unit, and a measurement unit. The first end of the first sampling resistor is connected to the first end (positive terminal) of its corresponding battery, and the second end of the first sampling resistor is connected to a first sampling port. The first end of the second sampling resistor is connected to the second end (negative terminal) of its corresponding battery, and the second end of the second sampling resistor is connected to a second sampling port. The sampling port is located at an Analog Front End (AFE). The resistance values ​​of the first and second sampling resistors are equal.

[0041] The switching unit is used to switch the working mode of the detection unit. The adjustment unit is used to adjust the resistance value between the battery corresponding to the detection unit and the sampling port according to the working mode of the detection unit. The measurement unit is configured to collect the first voltage difference between the first sampling port and the second sampling port when the detection unit is working in the first working mode, and the second voltage difference between the first sampling port and the second sampling port when the detection unit is working in the second working mode, and determine whether the battery corresponding to the detection unit is disconnected and whether it is leaking current based on the first voltage difference and the second voltage difference.

[0042] Figure 4 A schematic diagram of the detection circuit according to a first embodiment of the present invention is shown. Figure 5 It shows Figure 4 A schematic diagram of a detection unit in the detection circuit shown.

[0043] See Figure 4 The detection circuit 500 provided in the first embodiment of the present invention is used to detect the battery pack 400. The battery pack 400 includes multiple batteries B1-Bn connected in series from top to bottom. The detection unit 510 includes two sampling resistors Rf, a capacitor C, an adjustment unit 511, a switching unit 512, and a measurement unit 513. Adjacent batteries can share a single sampling resistor Rf; that is, the second sampling resistor Rf of the detection unit 510 corresponding to the upper battery can be used as the first sampling resistor Rf of the detection unit 510 corresponding to the lower battery. For example, sampling resistor Rf2 is both the second sampling resistor Rf of the detection unit 510 corresponding to battery B1 and the first sampling resistor Rf of the detection unit 510 corresponding to battery B2.

[0044] In the first embodiment of the present invention, the adjustment unit 511 of each detection unit 510 is connected in parallel with its second sampling resistor Rf, the capacitor C is connected in parallel with the switching unit 512, and the capacitor C is connected between the first sampling port and the second sampling port.

[0045] The adjustment unit 511 includes a switch Q and a resistor Rp connected sequentially between the first and second terminals of the second sampling resistor Rf. The control terminal of the switch Q is connected to the second terminal of the second sampling resistor Rf. The switching unit 512 includes a resistor Rd and a switch S connected sequentially between the first sampling port and the second sampling port. The resistor Rd can also be replaced by a constant current source.

[0046] When switch S is off, detection unit 510 operates in the first operating mode. In this mode, switch Q is off, and the resistance between the second terminal of the battery corresponding to detection unit 510 and the second sampling port is the value of the second sampling resistor Rf. When switch S is on, detection unit 510 operates in the second operating mode. In this mode, switch Q is on, and the resistance between the second terminal of the battery corresponding to detection unit 510 and the second sampling port is the value of the second sampling resistor Rf connected in parallel with resistor Rp.

[0047] Optionally, the detection units 510 corresponding to batteries B1-Bn can detect batteries B1-Bn simultaneously. In this case, the working modes of the detection units 510 corresponding to batteries B1-Bn are synchronized.

[0048] Optionally, the detection unit 510 corresponding to batteries B1-Bn can detect one of the batteries B1-Bn individually. In this case, the working modes of the detection units 510 corresponding to batteries B1-Bn are not synchronized.

[0049] The connection relationship of the components in detection unit 510 will be explained below using detection unit 510 corresponding to battery B1 as an example. (See below) Figure 5 The first terminal (positive) of battery B1 is connected to the first terminal of the first sampling resistor Rf1, and the second terminal of the first sampling resistor Rf1 is connected to the first sampling port A0 of the analog front end. The second terminal (negative) of battery B1 is connected to the first terminal of the second sampling resistor Rf2, and the second terminal of the sampling resistor Rf2 is connected to the second sampling port A1 of the analog front end. The adjustment unit 511 is connected in parallel with the second sampling resistor Rf2. The switch Q1 and the resistor Rp1 are connected in sequence between the first and second terminals of the second sampling resistor Rf2. The control terminal of the switch Q1 is connected to the second terminal of the second sampling resistor Rf2. The first terminal of capacitor C1 is connected to the second terminal of the first sampling resistor Rf1, and the second terminal of capacitor C1 is connected to the second terminal of the second sampling resistor Rf2. The switching unit 512 is connected in parallel with capacitor C1. A measurement unit 513 is also connected between the first sampling port A0 and the second sampling port A1. The measurement unit 513 is used to measure the voltage difference between the first sampling port A0 and the second sampling port A1, and to determine whether the battery is disconnected and whether it is leaking current based on the first voltage difference when the detection unit 510 is operating in the first operating mode and the second voltage difference when it is operating in the second operating mode. It also calculates the disconnection impedance of the battery when it is disconnected and the leakage current of the battery when it is leaking current.

[0050] Taking battery B1 as an example, when detecting battery B1, assume that the absorption current at the sampling port is I.

[0051] If battery B1 is disconnected, and the disconnection resistance is Ropen, then when the detection unit 510 corresponding to battery B1 is operating in the first operating mode, the first voltage difference measured by the measurement unit 513 is:

[0052] V1 = V cell -(Ropen+2Rf)*I (1)

[0053] Among them, V cell Ropen represents the voltage value of battery B1, Ropen represents the open circuit resistance value of battery B1, I represents the absorption current of the sampling port during sampling, and Rf represents the resistance values ​​of the first sampling resistor Rf1 and the second sampling resistor Rf2.

[0054] Then, the corresponding detection unit 510 is set to operate in the second operating mode. At this time, the second voltage difference measured by the measurement unit 513 is:

[0055]

[0056] Among them, V cellRopen represents the voltage value of battery B1, Ropen represents the open circuit resistance value of battery B1, I represents the absorption current of the sampling port during sampling, Rf represents the resistance value of the first sampling resistor Rf1 and the second sampling resistor Rf2, Rp represents the resistance value of resistor Rp, and Rd represents the resistance value of resistor Rd.

[0057]

[0058] Therefore, we can conclude that:

[0059]

[0060] Set Ropen = 1KΩ, V cell =3.3V, Rf=Rd=1KΩ, Rp=3KΩ, I=1uA, C=10nF. Substituting these values ​​into formulas (1) and (2), we can obtain V1=3.297V and V2=0.879V.

[0061] V cell =3.3V, Rf=Rd=1KΩ, Rp=3KΩ, I=1uA, C=10nF. Inputting the simulation circuit, the first voltage difference V1=3.295V and the second voltage difference V2=0.892V can be obtained through simulation. Substituting these values ​​into formula (4) yields...

[0062]

[0063] Therefore, it can be seen that the detection circuit 500 provided in the first embodiment of the present invention has a very small error in the measured disconnection impedance Ropen when detecting the disconnection of battery B1.

[0064] If battery B1 leaks current, and the leakage current is I1, then when the detection unit 510 corresponding to battery B1 is operating in the first operating mode, the first voltage difference measured by the measurement unit 513 is:

[0065] V3 = V cell -2Rf*(I+I1)(5)

[0066] Among them, V cell I represents the voltage value of battery B1, I1 represents the leakage current, I represents the absorption current of the sampling port during sampling, and Rf represents the resistance value of the first sampling resistor Rf1 and the second sampling resistor Rf2.

[0067] When the detection unit 510 corresponding to battery B1 is operating in the second operating mode, the second voltage difference measured by the measurement unit 513 is:

[0068]

[0069] Among them, V cellThe voltage value of battery B1 is represented by I1, the leakage current is represented by I, the current absorbed by the sampling port during sampling is represented by I, the resistance value of the first sampling resistor Rf1 and the second sampling resistor Rf2 is represented by Rp, and the resistance value of resistor Rd is represented by Rd.

[0070]

[0071] This leads to the conclusion that

[0072]

[0073] Similarly, V is set. cell =3.3V, Rf=Rd=1KΩ, Rp=3KΩ, I=1uA, I1=100uA, C=10nF. Substituting these values ​​into formulas (5) and (6), we can obtain V3=3.098V and V4=1.136V.

[0074] V cell =3.3V, Rf=Rd=1KΩ, Rp=3KΩ, I=1uA, C=10nF. Inputting the simulation circuit, the first voltage difference V3=3.098V and the second voltage difference V4=1.189V can be obtained through simulation. Substituting these values ​​into equation (8) yields...

[0075]

[0076] Therefore, it can be seen that the detection circuit 500 provided in the first embodiment of the present invention has a very small error in the measured leakage current I1 when performing leakage detection on battery B1.

[0077] Figure 6 A schematic diagram of the detection circuit according to a second embodiment of the present invention is shown. Figure 7 It shows Figure 6 A schematic diagram of a detection unit in the detection circuit shown.

[0078] See Figure 6 The detection circuit 600 provided in the second embodiment of the present invention is used to detect the battery pack 400. The battery pack 400 includes multiple batteries B1-Bn connected in series from top to bottom. The detection unit 610 includes two sampling resistors Rf, a capacitor C, an adjustment unit 611, a switching unit 612, and a measurement unit 613. Adjacent batteries can share a single sampling resistor Rf; that is, the second sampling resistor Rf of the detection unit 610 corresponding to the upper battery can be used as the first sampling resistor Rf of the detection unit 610 corresponding to the lower battery. For example, sampling resistor Rf2 is both the second sampling resistor Rf of the detection unit 610 corresponding to battery B1 and the first sampling resistor Rf of the detection unit 610 corresponding to battery B2.

[0079] In the second embodiment of the present invention, the adjustment unit 611 of each detection unit 610 is connected in parallel with its first sampling resistor Rf, the first end of the capacitor C is connected to the second end of the first sampling resistor Rf, and the second end of the capacitor C is grounded. The switching unit 612 is connected between the first sampling port and the second sampling port.

[0080] The adjustment unit 611 includes a switch Q and a resistor Rp connected sequentially between the first and second terminals of the first sampling resistor Rf. The control terminal of the switch Q is connected to the second terminal of the first sampling resistor Rf. The switching unit 612 includes a resistor Rd and a switch S connected sequentially between the first sampling port and the second sampling port. The resistor Rd can also be replaced by a constant current source.

[0081] When switch S is off, detection unit 610 operates in the first operating mode. In this mode, switch Q is off, and the resistance between the second terminal of the battery corresponding to detection unit 610 and the first sampling port is the value of the first sampling resistor Rf. When switch S is on, detection unit 610 operates in the second operating mode. In this mode, switch Q is on, and the resistance between the second terminal of the battery corresponding to detection unit 610 and the first sampling port is the value of the first sampling resistor Rf connected in parallel with resistor Rp.

[0082] Optionally, the detection units 610 corresponding to batteries B1-Bn can detect batteries B1-Bn simultaneously. In this case, the working modes of the detection units 610 corresponding to batteries B1-Bn are synchronized.

[0083] Optionally, the detection unit 610 corresponding to batteries B1-Bn can detect one of the batteries B1-Bn individually. In this case, the working modes of the detection units 610 corresponding to batteries B1-Bn are not synchronized.

[0084] The connection relationship of the components in detection unit 610 will be explained below using detection unit 610 corresponding to battery B1 as an example. (See below) Figure 7The first terminal (positive terminal) of battery B1 is connected to the first terminal of the first sampling resistor Rf1, the second terminal of the first sampling resistor Rf1 is connected to the first sampling port A0 of the analog front end, the second terminal (negative terminal) of battery B1 is connected to the first terminal of the second sampling resistor Rf2, and the second terminal of the second sampling resistor Rf2 is connected to the second sampling port A1 of the analog front end; the adjustment unit 611 is connected in parallel with the first sampling resistor Rf1, the switch Q1 and the resistor Rp1 are connected sequentially between the first terminal and the second terminal of the first sampling resistor Rf1, the control terminal of the switch Q1 is connected to the second terminal of the first sampling resistor Rf1; the first terminal of capacitor C1 is connected to the second terminal of the first sampling resistor Rf1, and the second terminal of capacitor C1 is grounded; the switching unit 612 is connected between the first sampling port A0 and the second sampling port A1; a measurement unit 613 is also connected between the first sampling port A0 and the second sampling port A1. The measurement unit 613 is used to measure the voltage difference between the first sampling port A0 and the second sampling port A1, and to determine whether the battery is disconnected and whether it is leaking current based on the first voltage difference when the detection unit 610 is operating in the first operating mode and the second voltage difference when it is operating in the second operating mode. It also calculates the disconnection impedance of the battery when it is disconnected and the leakage current of the battery when it is leaking current.

[0085] Taking battery B1 as an example again, when performing a wire breakage detection on battery B1, the detection method of detection circuit 600 and the calculation method of wire breakage impedance Ropen are the same as those of detection circuit 500, and will not be repeated here.

[0086] When performing leakage current detection on battery B1, although the detection method of detection circuit 600 is the same as that of detection circuit 500, the calculation method of leakage current I1 is different.

[0087] Specifically, if battery B1 leaks current, when the detection unit 610 corresponding to battery B1 is operating in the first working mode, the first voltage difference measured by the measurement unit 613 is:

[0088] V5 = V cell -Rf*(I+I1)-Rf*I(9)

[0089] Among them, V cell I represents the voltage value of battery B1, I1 represents the leakage current, I represents the absorption current of the sampling port during sampling, and Rf represents the resistance value of the first sampling resistor Rf1 and the second sampling resistor Rf2.

[0090] When the detection unit 610 corresponding to battery B1 is operating in the second operating mode, the second voltage difference measured by the measurement unit 613 is:

[0091]

[0092] Among them, V cellThe voltage value of battery B1 is represented by I1, the leakage current is represented by I, the current absorbed by the sampling port during sampling is represented by I, the resistance value of the first sampling resistor Rf1 and the second sampling resistor Rf2 is represented by Rp, and the resistance value of resistor Rd is represented by Rd.

[0093]

[0094] Therefore, we can conclude that:

[0095]

[0096] Set Ropen = 1KΩ, V cell =3.3V, Rf=Rd=1KΩ, Rp=3KΩ, I=1uA, C=10nF. Substituting these values ​​into formulas (1) and (2), we can obtain V5=3.198V and V6=1.712V.

[0097] V cell =3.3V, Rf=Rd=1KΩ, Rp=3KΩ, I=1uA, C=10nF. Inputting the simulation circuit, the first voltage difference V5=3.098V and the second voltage difference V6=1.189V can be obtained through simulation. Substituting these values ​​into formula (12) yields...

[0098]

[0099] Therefore, it can be seen that the detection circuit 600 provided in the second embodiment of the present invention has a very small error in the measured leakage current I1 when performing leakage detection on battery B1.

[0100] Figure 8 A schematic diagram of the detection circuit according to a third embodiment of the present invention is shown. See also Figure 8 The power transistor Q can be set as two MOSFETs connected in series, and both MOSFETs can be set as low-voltage NMOS transistors.

[0101] Optionally, the detection circuit provided by the present invention can adapt to different disconnection resistance values ​​by setting the resistance ratio of sampling resistor Rf, resistor Rd and resistor Rp, which is suitable for cases where the disconnection resistance value is small.

[0102] The detection circuit for a battery pack provided in this embodiment of the invention includes multiple detection units corresponding one-to-one with multiple batteries in the battery pack. Each detection unit includes a first sampling resistor, a second sampling resistor, a capacitor, an adjustment unit, a switching unit, and a measurement unit. The first end of the first sampling resistor is connected to the first end of the battery corresponding to the detection unit, and the second end of the first sampling resistor is connected to a first sampling port. The first end of the second sampling resistor is connected to the second end of the battery corresponding to the detection unit, and the second end of the second sampling resistor is connected to a second sampling port. When detecting the battery corresponding to the detection unit, it is only necessary to sample the first voltage difference between the first sampling port and the second sampling port when the detection unit is working in the first working mode, and the second voltage difference between the first sampling port and the second sampling port when the detection unit is working in the second working mode. Based on the first voltage difference and the second voltage difference, it is possible to determine whether the battery is disconnected and whether it is leaking current. When the battery is disconnected, the disconnection impedance of the battery is calculated, and when the battery is leaking current, the leakage current of the battery is calculated. This detection circuit can simultaneously detect disconnection and leakage current of the battery, saving time and is not limited by disconnection impedance or whether the AFE has a balancing pin.

[0103] The present invention also provides a detection method for a battery pack, the detection method being implemented using the detection circuit described above, comprising:

[0104] Switch the detection unit of the battery to be tested to the first working mode, and obtain the first voltage difference between the first sampling port and the second sampling port when the first working mode is used;

[0105] Switch the detection unit of the battery under test to the second working mode, and obtain the second voltage difference between the first sampling port and the second sampling port when the second working mode is used;

[0106] Based on the first voltage difference and the second voltage difference, determine whether the battery under test is leaking current and whether it is disconnected; and

[0107] Calculate the disconnection resistance when the battery under test is disconnected, and calculate the leakage current when the battery under test is leaking.

[0108] As described above, these embodiments of the present invention do not exhaustively describe all details, nor do they limit the invention to specific embodiments. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The scope of protection of this invention should be determined by the scope defined in the claims and their equivalents.

Claims

1. A detection circuit for a battery pack, the battery pack comprising a plurality of batteries connected in series, the detection circuit comprising: Multiple detection units, each corresponding to one of the multiple batteries, each detection unit includes a first sampling resistor, a second sampling resistor, a capacitor, an adjustment unit, a switching unit, and a measurement unit. Wherein, the first end of the first sampling resistor is connected to the first end of the battery corresponding to the detection unit, and the second end of the first sampling resistor is connected to the first sampling port; The first end of the second sampling resistor is connected to the second end of the battery corresponding to the detection unit, and the second end of the second sampling resistor is connected to the second sampling port; The switching unit is used to switch the working mode of the detection unit; The adjustment unit is used to adjust the resistance value between the corresponding battery of the detection unit and the first sampling port or the second sampling port according to the working mode of the detection unit. The measuring unit is used to measure a first voltage difference between the first sampling port and the second sampling port when the detection unit operates in a first operating mode, and a second voltage difference between the first sampling port and the second sampling port when the detection unit operates in a second operating mode, and to determine whether the battery corresponding to the detection unit is disconnected and whether it is leaking current based on the first voltage difference and the second voltage difference. The switching unit includes a first resistor and a switch connected between the first sampling port and the second sampling port, or it includes a constant current source and a switch connected between the first sampling port and the second sampling port. The operating mode of the detection unit is achieved by switching the switch on and off.

2. The detection circuit according to claim 1, wherein, The measuring unit is also used to calculate the disconnection resistance when the battery corresponding to the detection unit is disconnected, and to calculate the leakage current when the battery corresponding to the detection unit is leaking.

3. The detection circuit according to claim 2, wherein, The adjustment unit is connected in parallel with the second sampling resistor; The first end of the capacitor is connected to the second end of the first sampling resistor, and the second end of the capacitor is connected to the second end of the second sampling resistor.

4. The detection circuit according to claim 3, wherein, The adjustment unit includes: A switching transistor and a second resistor are sequentially connected between the first and second terminals of the second sampling resistor, with the control terminal of the switching transistor connected to the second terminal of the second sampling resistor. The switching on and off of the switching transistor is synchronized with the switching on and off of the switch.

5. The detection circuit according to claim 2, wherein, The adjustment unit is connected in parallel with the first sampling resistor; The first terminal of the capacitor is connected to the second terminal of the first sampling resistor, and the second terminal of the capacitor is grounded.

6. The detection circuit according to claim 5, wherein, The adjustment unit includes: A switching transistor and a third resistor are sequentially connected between the first and second terminals of the first sampling resistor, with the control terminal of the switching transistor connected to the second terminal of the first sampling resistor. The switching on and off of the switching transistor is synchronized with the switching on and off of the switch.

7. The detection circuit according to claim 4 or 6, wherein, The switching transistor includes two MOSFETs connected in sequence, and the MOSFETs are low-voltage MOSFETs.

8. A detection method for a battery pack, the detection method being implemented using the detection circuit as described in any one of claims 1-7, the detection method comprising: By turning off the switch in the switching unit, the detection unit of the battery to be tested is switched to the first working mode. At this time, the switch in the adjustment unit is turned off, and the first voltage difference between the first sampling port and the second sampling port is obtained in the first working mode. By turning on the switch in the switching unit, the detection unit of the battery to be tested is switched to the second working mode. At this time, the switch in the adjustment unit is turned on, and the second voltage difference between the first sampling port and the second sampling port in the second working mode is obtained. Based on the first voltage difference and the second voltage difference, determine whether the battery under test is leaking current and whether it is disconnected; as well as Calculate the disconnection resistance when the battery under test is disconnected, and calculate the leakage current when the battery under test is leaking.

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