BMS current detection circuit and method

Abstract

The invention discloses a BMS current detection circuit and method, the BMS current detection circuit comprises a control module and a current sampling circuit module, and the control module and the current sampling circuit module are connected to the positive and negative ends of a battery respectively after being connected; the current sampling circuit module comprises a current sampler, a current detection unit, a discharge control unit and a charge control unit; the current detection unit, the load unit and the charging control unit are mutually connected; the current detection unit comprises one or more current detection sub-circuits, the discharge control unit comprises one or more discharge control sub-circuits, and the charge control unit comprises one or more charge control sub-circuits; the number of the current detection sub-circuits, the number of the discharge control sub-circuits and the number of the charge control sub-circuits are the same. The control module controls the conduction number of the current detection sub-circuit, the discharge control sub-circuit and the charge control sub-circuit.

Description

Technical Field

[0001] The present application belongs to the technical field of battery management systems, and specifically refers to a BMS current detection circuit and method. Background Art

[0002] In the vehicle field, when the current battery management system detects the battery current, the maximum current of the board to be detected is hundreds or thousands of amperes, while the minimum current is only tens of milliamperes. Therefore, the current detection ADC of the battery management system needs to have a high resolution. When the maximum current is ±1000A and the minimum current is ±10mA, the dynamic range of the current detection ADC needs to reach 1:100,000, so at least an 18-bit current detection ADC is required. If the linearity and drift of the current detection ADC are considered to affect the effective number of bits, the actual number of bits required for the current detection ADC will be higher, so the difficulty and cost of implementation are relatively high. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present application provides a BMS current detection circuit and method, which improves the current detection range by changing the number of sub-circuits connected to the detection circuit to change the actual equivalent current detection resistor.

[0004] The present invention provides a BMS current detection circuit, the BMS current detection circuit comprising a control module and a current sampling circuit module, the control module and the current sampling circuit module are connected to the positive and negative terminals of the battery respectively; The current sampling circuit module includes a current sampler, a current detection unit, a discharge control unit and a charging control unit; the first input end and the second input end of the current sampler are connected to the control module, the output end of the current sampler is connected to the current detection unit, the first input end of the current sampler is also connected to the discharge control unit, and the control module is connected to the charging control unit; the current detection unit, the discharge control unit and the charging control unit are connected to each other; Among them, the current detection unit includes one or more current detection sub-circuits, the discharge control unit includes one or more discharge control sub-circuits, and the charging control unit includes one or more charging control sub-circuits; the number of the current detection sub-circuits, the discharge control sub-circuits and the charging control sub-circuits is the same; the control module controls the number of the current detection sub-circuits, the discharge control sub-circuits and the charging control sub-circuits that are turned on according to the current size in the BMS current detection circuit; a certain number of the current detection sub-circuits and the discharge control sub-circuits remain in the turned-on state.

[0005] Furthermore, the control module includes a micro control unit or a battery sampling chip.

[0006] Furthermore, the control module at least includes a charging control terminal, a discharging control terminal, a pulse signal output terminal, a current sampling positive terminal and a current sampling negative terminal; Among them, the first input end of the current sampler is connected to the discharge control end, the second output end of the current sampler is connected to the pulse signal output end, the current detection unit is connected to the current sampling positive end and the current sampling negative end, and the charging control unit is connected to the charging control end. Furthermore, each current detection subcircuit in the current detection unit includes a current detection resistor, a positive-end current detection mixed resistor and a negative-end current detection mixed resistor, and the current detection resistor is respectively connected in series with the positive-end current detection mixed resistor and the negative-end current detection mixed resistor to form the current detection subcircuit; Wherein, at least two current detection sub-circuits in the current detection unit are connected in parallel to form a first current detection group, and all other current detection sub-circuits in the current detection unit are connected in parallel to form a second current detection group.

[0007] Furthermore, the current detection unit further comprises a positive-end current detection mixed signal switch and a negative-end current detection mixed signal switch; the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are connected to each current detection sub-circuit in the second current detection group; each current detection sub-circuit in the second current detection group is turned on according to the control of the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch; the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are connected to the output end of the current sampler, and the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are controlled by the current sampler; the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are also connected to the control module; Among them, the positive-end current detection mixed signal switch is connected to the positive-end current detection mixed resistor in each current detection sub-circuit in the second current detection group, and the negative-end current detection mixed signal switch is connected to the negative-end current detection mixed resistor in each current detection sub-circuit in the second current detection group; the current detection sub-circuits in the first current detection group are not connected to the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch. Further, the first current detection subcircuit and the second current detection subcircuit in the current detection unit are connected in parallel to form the first current detection group; the first current detection subcircuit and the second current detection subcircuit in the current detection unit are not connected to the first current detection mixed signal switch and the second current detection mixed signal switch, and the first current detection subcircuit and the second current detection subcircuit remain in a conducting state; The other current detection sub-circuits in the current detection unit are all connected to the first current detection mixed signal switch and the second current detection mixed signal switch, and the other current detection sub-circuits in the current detection unit are turned on according to the control of the positive end current detection mixed signal switch and the negative end current detection mixed signal switch. Further, each of the discharge control subcircuits in the discharge control unit includes a discharge control resistor and a discharge control switch, and the discharge control resistor is connected to the discharge control switch; each of the discharge control subcircuits is connected to the first input terminal of the current sampler; At least two of the discharge control subcircuits in the discharge control unit are connected in parallel to form a first discharge control circuit group, and all other discharge control subcircuits in the discharge control unit are connected in parallel to form a second discharge control circuit group. Furthermore, the first discharge control circuit group is connected to the first input end of the current sampler, and the second discharge control circuit group is connected to the output end of the current sampler; the first discharge control circuit group is connected to the first current detection group, and the second discharge control circuit group is connected to the second current detection group.

[0008] Further, each of the charging control subcircuits in the charging control unit includes a driving resistor and a charging control switch, and the driving resistor is connected to the charging control switch; each of the charging control subcircuits is connected to the control module; Wherein, each of the charging control subcircuits are connected in parallel with each other; and the charging control subcircuit and the discharging control subcircuit are connected with each other.

[0009] The present application also provides a current detection method based on the BMS current detection circuit provided in the present application, the current detection method comprising: The control module detects whether the current current value exceeds the threshold value. If the current current value does not exceed the threshold value, the current sampling circuit module enters the low current detection mode; if the current current value exceeds the threshold value, the current sampling circuit module enters the high current detection mode; When the current sampling circuit module is in the low current detection mode, only one or two current detection sub-circuits in the current detection unit of the current sampling circuit module are turned on, and only one or two discharge control sub-circuits or charging control sub-circuits in the discharge control unit package or the charging control unit of the current sampling circuit module are turned on; the current sampling circuit module performs current sampling of low current; When the current sampling circuit module is in the large current detection mode, the control module controls several current detection sub-circuits in the current detection unit to be turned on, and the control module controls several discharge control sub-circuits or charging control sub-circuits in the discharge control unit package or the charging control unit to be turned on; the current sampling circuit module performs current sampling of large currents.

[0010] The beneficial effects of the present invention are as follows: the present application provides a BMS current detection circuit and method, the BMS current detection circuit includes multiple current detection subcircuits, multiple discharge control subcircuits and multiple charging control subcircuits, and the number of multiple current detection subcircuits, multiple discharge control subcircuits and multiple charging control subcircuits connected to the current detection circuit is dynamically controlled according to the size of the discharge control current through the coordinated control of the control module. Thereby changing the size of the actual equivalent current detection resistor to improve the current detection range and the resolution and accuracy under low current. The method of the BMS current detection circuit is also relatively simple and efficient, and different current detection resistors are matched for different current sizes of discharge control. Thereby achieving different resolutions of current detection ADCs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0012] Figure 1 This is a schematic diagram of the structure of the BMS current detection circuit provided in this embodiment.

[0013] Figure 2 A schematic diagram of a BMS current detection circuit provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0015] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0016] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0017] The embodiments of the present application are now further described in conjunction with the accompanying drawings and specific implementation methods.

[0018] Figure 1 This is a schematic diagram of the structure of the BMS current detection circuit provided in this embodiment.

[0019] like Figure 1 As shown, the BMS current detection circuit includes a control module and a current sampling circuit module. The control module and the current sampling circuit module are connected to the positive and negative ends of the battery respectively. The battery is composed of a number of battery packs, and the control module controls the battery to discharge the load or charge the battery with an external power supply. The current sampling circuit module detects the current size in the circuit.

[0020] In this embodiment, the current sampling circuit module includes a current sampler, a current detection unit, a discharge control unit and a charging control unit; the first input end and the second input end of the current sampler are connected to the control module, the output end of the current sampler is connected to the current detection unit, the first input end of the current sampler is also connected to the discharge control unit, and the control module is connected to the charging control unit; the current detection unit, the discharge control unit and the charging control unit are connected to each other.

[0021] Wherein, the current detection unit includes one or more current detection subcircuits, the discharge control unit includes one or more discharge control subcircuits, and the charge control unit includes one or more charge control subcircuits; the number of the current detection subcircuits, the discharge control subcircuits, and the charge control subcircuits is the same; the control module controls the number of the current detection subcircuits, the discharge control subcircuits, and the charge control subcircuits that are turned on according to the current size in the BMS current detection circuit. Moreover, a certain number of the current detection subcircuits and the discharge control subcircuits are set in the current detection unit and the discharge control unit in a normally on state.

[0022] Specifically, the current detection subcircuit and the discharge control subcircuit in the normally on state can collect the current when the BMS current detection circuit is in the low current mode. If the current in the BMS current detection circuit exceeds the current in the current low current mode, the control module dynamically controls the conduction number of the current detection subcircuit, the discharge control subcircuit and the charge control subcircuit according to the current in the BMS current detection circuit in the circuit, thereby changing the equivalent resistance of the current detection unit to improve the current detection range and the resolution and accuracy under different currents.

[0023] In one embodiment, the control module includes a micro control unit or a battery sampling chip. In this embodiment, the control module is described as a battery sampling chip (analog front end, referred to as AFE) as an example.

[0024] like Figure 2 As shown, the battery sampling chip (AFE) at least includes a charging control terminal (CHG), a discharging control terminal (DSG), a pulse signal output terminal (Hi-mode), a current sampling positive terminal (SRP) and a current sampling negative terminal (SRN); Among them, the first input end of the current sampler is connected to the discharge control end (DSG), the second output end of the current sampler is connected to the pulse signal output end (Hi-mode), the current detection unit is connected to the current sampling positive end (SRP) and the current sampling negative end (SRN), and the charging control unit is connected to the charging control end (CHG).

[0025] In one embodiment, each current detection sub-circuit in the current detection unit includes a current detection resistor, a positive-end current detection mixed resistor and a negative-end current detection mixed resistor, and the current detection resistor is respectively connected in series with the positive-end current detection mixed resistor and the negative-end current detection mixed resistor to form the current detection sub-circuit.

[0026] Wherein, at least two current detection sub-circuits in the current detection unit are connected in parallel to form a first current detection group, and all other current detection sub-circuits in the current detection unit are connected in parallel to form a second current detection group.

[0027] The current detection unit also includes a positive-end current detection mixed signal switch Qap and a negative-end current detection mixed signal switch Qan; the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are connected to each of the current detection sub-circuits in the second current detection group; each of the current detection sub-circuits in the second current detection group is turned on according to the control of the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan. The positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are connected to the output end of the current sampler, and the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are controlled by the current sampler. The positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are also connected to the control module.

[0028] The positive-end current-detection mixed signal switch Qap is connected to the positive-end current-detection mixed resistor in each current-detection sub-circuit in the second current-detection group, and the negative-end current-detection mixed signal switch Qan is connected to the negative-end current-detection mixed resistor in each current-detection sub-circuit in the second current-detection group. The current-detection sub-circuits in the first current-detection group are not connected to the positive-end current-detection mixed signal switch Qap and the negative-end current-detection mixed signal switch Qan.

[0029] The positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch are both MOS tube switches, and the gates of the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are both connected to the output end of the current sampler, and the source and drain of the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are both connected to each of the current detection sub-circuits in the second current detection group. The output end of the current sampler controls the gates of the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan to be turned on, thereby turning on the source and drain of the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan. In this way, the number of current detection sub-circuits turned on is controlled.

[0030] Each of the discharge control subcircuits in the discharge control unit includes a discharge control resistor and a discharge control switch, and the discharge control resistor is connected to the discharge control switch; each of the discharge control subcircuits is connected to the first input end of the current sampler.

[0031] At least two of the discharge control subcircuits in the discharge control unit are connected in parallel to form a first discharge control circuit group, and all other discharge control subcircuits in the discharge control unit are connected in parallel to form a second discharge control circuit group.

[0032] The first discharge control circuit group is connected to the first input end of the current sampler, and the second discharge control circuit group is connected to the output end of the current sampler; the first discharge control circuit group is connected to the first current detection group, and the second discharge control circuit group is connected to the second current detection group.

[0033] Each charging control subcircuit in the charging control unit includes a driving resistor and a charging control switch, wherein the driving resistor is connected to the charging control switch; each charging control subcircuit is connected to the control module. Each charging control subcircuit is connected in parallel with each other; and the charging control subcircuit is connected to the discharge control subcircuit.

[0034] In another embodiment, Figure 2 As shown, the first current detection subcircuit and the second current detection subcircuit in the current detection unit are connected in parallel to form the first current detection group; the first current detection subcircuit and the second current detection subcircuit in the current detection unit are not connected to the first current detection mixed signal switch and the second current detection mixed signal switch, and the first current detection subcircuit and the second current detection subcircuit remain in a conducting state; The other current detection sub-circuits in the current detection unit are all connected to the first current detection mixed signal switch and the second current detection mixed signal switch, and the other current detection sub-circuits in the current detection unit are turned on according to the control of the positive end current detection mixed signal switch and the negative end current detection mixed signal switch.

[0035] Specifically, the first current detection subcircuit includes a first current detection resistor Rs1, a first positive-end current detection mixed resistor Rp1 and a first negative-end current detection mixed resistor Rn1, and the first positive-end current detection mixed resistor Rp1, the first current detection resistor Rs1 and the first negative-end current detection mixed resistor Rn1 are connected in series in sequence.

[0036] The second current detection subcircuit includes a second current detection resistor Rs2, a second positive-end current detection mixed resistor Rp2 and a second negative-end current detection mixed resistor Rn2, wherein the second positive-end current detection mixed resistor Rp2, the second current detection resistor Rs2 and the second negative-end current detection mixed resistor Rn2 are connected in series in sequence.

[0037] The third current detection subcircuit includes a third current detection resistor Rs3, a third positive-end current detection mixed resistor Rp3 and a third negative-end current detection mixed resistor Rn3, wherein the third positive-end current detection mixed resistor Rp3, the third current detection resistor Rs3 and the third negative-end current detection mixed resistor Rn3 are connected in series in sequence.

[0038] By analogy, the nth current detection subcircuit includes the nth current detection resistor Rs2, the nth positive-end current detection mixed resistor Rpn and the nth negative-end current detection mixed resistor Rnn, and the nth positive-end current detection mixed resistor Rpn, the nth current detection resistor Rsn and the nth negative-end current detection mixed resistor Rnn are connected in series in sequence.

[0039] The first current detection sub-circuit and the second current detection sub-circuit are connected in parallel, and the third current detection sub-circuit, ..., and the nth current detection sub-circuit are connected in parallel with each other.

[0040] The positive-end current-detecting mixed signal switch Qap and the negative-end current-detecting mixed signal switch Qan are both MOS tube switches, and the positive-end current-detecting mixed signal switch Qap and the negative-end current-detecting mixed signal switch Qan are NMOS tubes.

[0041] In this embodiment, the first current detection subcircuit and the second current detection subcircuit are not connected to the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan. The third current detection subcircuit to the nth current detection subcircuit are all connected to the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan. The first current detection subcircuit and the second current detection subcircuit are connected in parallel with each other. The third current detection subcircuit to the nth current detection subcircuit are connected in parallel with each other.

[0042] Specifically, the gate of the positive-end current-detecting mixed signal switch Qap is connected to the positive-end current-limiting resistor Ragp, and then connected to the output terminal Gdrv3 of the current sampler; the source of the positive-end current-detecting mixed signal switch Qap is connected to the parallel electrical node of the third current detection sub-circuit to the nth current detection sub-circuit; the drain of the positive-end current-detecting mixed signal switch Qap is connected to the parallel electrical node of the first current detection sub-circuit and the second current detection sub-circuit and the current sampling positive terminal (SRP) of the battery sampling chip.

[0043] The gate of the negative-end current-detecting mixed signal switch Qan is connected to the negative-end current-limiting resistor Ragn, and then connected to the output terminal Gdrv3 of the current sampler; the source of the negative-end current-detecting mixed signal switch Qan is connected to the third current detection subcircuit to another parallel electrical node of the nth current detection subcircuit; the drain of the negative-end current-detecting mixed signal switch Qan is connected to another parallel electrical node of the first current detection subcircuit and the second current detection subcircuit and the current sampling negative terminal (SRN) of the battery sampling chip.

[0044] In this embodiment, the positive-end current detection mixed signal switch Qap and the negative-end current detection mixed signal switch Qan are not connected to the first current detection subcircuit and the second current detection subcircuit after being connected in parallel. That is, the first current detection subcircuit and the second current detection subcircuit can remain normally on and always connected to the BMS current detection circuit. The first current detection resistor Rs1, the first positive-end current detection mixed resistor Rp1 and the first negative-end current detection mixed resistor Rn1 in the first current detection subcircuit, and the second current detection resistor Rs2, the second positive-end current detection mixed resistor Rp2 and the second negative-end current detection mixed resistor Rn2 in the second current detection subcircuit can directly constitute an equivalent current detection resistor for current sampling. At this time, the resistance value of the equivalent current detection resistor in the BMS current detection circuit is relatively large, so smaller current changes can be distinguished to sample small currents in the BMS current detection circuit.

[0045] like Figure 2As shown, in the discharge control unit, the first discharge control subcircuit includes a first discharge control resistor Rdg1 and a first discharge control switch Qd1; wherein the first discharge control switch Qd1 is a MOS tube switch.

[0046] The second discharge control subcircuit includes a second discharge control resistor Rdg2 and a second discharge control switch Qd2; wherein the second discharge control switch Qd2 is a MOS tube switch.

[0047] The third discharge control subcircuit includes a third discharge control resistor Rdg3 and a third discharge control switch Qd3; wherein the third discharge control switch Qd3 is a MOS tube switch.

[0048] By analogy, the nth discharge control subcircuit includes an nth discharge control resistor Rdgn and an nth discharge control switch Qdn; wherein the nth discharge control switch Qdn is a MOS tube switch.

[0049] The first discharge control subcircuit and the second discharge control subcircuit are connected in parallel, and the third discharge control subcircuit, ..., and the nth discharge control subcircuit are connected in parallel with each other.

[0050] In the charging control unit, the first charging control subcircuit includes a first driving resistor Rcg1 and a first charging control switch Qc1; wherein the first charging control switch Qc1 is a MOS tube switch.

[0051] The second charging control sub-circuit includes a second driving resistor Rcg2 and a second charging control switch Qc2; wherein the second charging control switch Qc2 is a MOS tube switch.

[0052] The third charging control sub-circuit includes a third driving resistor Rcg3 and a third charging control switch Qc3; wherein the third charging control switch Qc3 is a MOS tube switch.

[0053] By analogy, the nth charging control subcircuit includes an nth driving resistor Rcgn and an nth charging control switch Qcn; wherein the nth charging control switch Qcn is a MOS tube switch.

[0054] The first charging control subcircuit and the second charging control subcircuit are connected in parallel, and the third charging control subcircuit, ..., and the nth charging control subcircuit are connected in parallel with each other.

[0055] Specifically, Figure 2As shown, the parallel structure of the first discharge control subcircuit and the second discharge control subcircuit is respectively connected to the parallel structure of the first current detection subcircuit and the second current detection subcircuit, and the parallel structure of the first charge control subcircuit and the second charge control subcircuit.

[0056] The gate of the first discharge control switch Qd1 in the first discharge control subcircuit is connected to one end of the first discharge control resistor Rdg1, and the other end of the first discharge control resistor Rdg1 is connected to the first input end Gdrv1 of the current sampler, and the first input end Gdrv1 of the current sampler is connected to the discharge control end (DSG) of the battery sampling chip. The source of the first discharge control switch Qd1 is connected to the parallel electrical node of the first current detection subcircuit and the second current detection subcircuit, and the drain of the first discharge control switch Qd1 is connected to the first charge control subcircuit.

[0057] The gate of the second discharge control switch Qd2 in the second discharge control subcircuit is connected to one end of the second discharge control resistor Rdg2, and the other end of the second discharge control resistor Rdg2 is connected to the first input end Gdrv1 of the current sampler, and the first input end Gdrv1 of the current sampler is connected to the discharge control end (DSG) of the battery sampling chip. The source of the second discharge control switch Qd2 is connected to the parallel electrical node of the first current detection subcircuit and the second current detection subcircuit, and the drain of the second discharge control switch Qd2 is connected to the second charge control subcircuit.

[0058] After the third discharge control subcircuit, ..., and the nth discharge control subcircuit are connected in parallel with each other, the gate of the discharge control switch in each discharge control subcircuit is connected to one end of the discharge control resistor of the circuit, and the other end of the discharge control resistor is connected to the output end Gdrv3 of the current sampler; the source of the discharge control switch in each discharge control subcircuit is connected to the parallel electrical node between the third current detection subcircuit, ..., and the nth current detection subcircuit; the drain of the discharge control switch in each discharge control subcircuit is connected to the parallel electrical node between the third charging control subcircuit, ..., and the nth charging control subcircuit.

[0059] The gate of the first charging control switch Qc1 in the first charging control subcircuit is connected to one end of the first driving resistor Rcg1, and the other end of the first driving resistor Rcg1 is connected to the charging control terminal (CHG) of the battery sampling chip. The source of the first charging control switch Qc1 is connected to the negative electrode of the battery, and the drain of the first charging control switch Qc1 is connected to the drain of the first discharge control switch Qd1.

[0060] The gate of the second charging control switch Qc2 in the second charging control subcircuit is connected to one end of the second driving resistor Rcg2, and the other end of the second driving resistor Rcg2 is connected to the charging control terminal (CHG) of the battery sampling chip. The source of the second charging control switch Qc2 is connected to the negative electrode of the battery, and the drain of the second charging control switch Qc2 is connected to the drain of the second discharge control switch Qd2.

[0061] By analogy, the gate of the nth charging control switch Qcn in the nth charging control subcircuit is connected to one end of the nth driving resistor Rcgn, and the other end of the nth driving resistor Rcgn is connected to the charging control terminal (CHG) of the battery sampling chip. The source of the nth charging control switch Qcn is connected to the negative electrode of the battery, and the drain of the nth charging control switch Qcn is connected to the drain of the nth discharge control switch Qdn.

[0062] like Figure 2 As shown, the BMS current detection circuit provided in this embodiment divides the current detection unit, the discharge control unit and the charge control unit into several sub-circuit units, and at least one sub-circuit unit is kept normally on. When the discharge control current in the circuit is a small current, only a small part of the current detection sub-circuit in the current detection unit has current flowing through it. At this time, the resistance value of the equivalent detection resistor in the circuit is relatively large, and smaller current changes can be distinguished. When the battery sampling chip detects that the discharge control current in the circuit exceeds the threshold value, the battery sampling chip enters the high current sampling mode, and controls the discharge control switch in the discharge control subcircuit of the discharge control unit to be closed, and simultaneously closes the positive terminal current detection mixed signal switch Qap and the negative terminal current detection mixed signal switch Qan. At this time, the number of current detection subcircuits connected to the circuit increases, and the resistance value of the equivalent detection resistor in the BMS current detection circuit becomes smaller. The current signal on the current detection resistor in each current detection subcircuit is linearly superimposed on the current differential signal line (i.e., the current sampling positive terminal (SRP) and the current sampling negative terminal (SRN)) through the positive terminal current detection mixed resistor Rp1~Rpn and the negative terminal current detection mixed resistor Rn1~Rnn. At this time, the BMS current detection circuit can detect a larger current signal.

[0063] This embodiment also provides a current detection method based on the BMS current detection circuit provided in this application, and the current detection method includes: The control module detects whether the current current value exceeds the threshold value. If the current current value does not exceed the threshold value, the current sampling circuit module enters the low current detection mode; if the current current value exceeds the threshold value, the current sampling circuit module enters the high current detection mode; When the current sampling circuit module is in the low current detection mode, only one or two current detection sub-circuits in the current detection unit of the current sampling circuit module are turned on, and only one or two discharge control sub-circuits or charging control sub-circuits in the discharge control unit package or the charging control unit of the current sampling circuit module are turned on; the current sampling circuit module performs current sampling of low current; When the current sampling circuit module is in the large current detection mode, the control module controls several current detection sub-circuits in the current detection unit to be turned on, and the control module controls several discharge control sub-circuits or charging control sub-circuits in the discharge control unit package or the charging control unit to be turned on; the current sampling circuit module performs current sampling of large currents.

[0064] The present application provides a BMS current detection circuit and method, wherein the BMS current detection circuit includes multiple current detection subcircuits, multiple discharge control subcircuits, and multiple charging control subcircuits. Through the coordinated control of the control module, the number of multiple current detection subcircuits, multiple discharge control subcircuits, and multiple charging control subcircuits connected to the current detection circuit is dynamically controlled according to the size of the discharge control current. Thereby changing the size of the actual equivalent current detection resistor to improve the current detection range and the resolution and accuracy under low current. The method of the BMS current detection circuit is also relatively simple and efficient, and different current detection resistors are matched for different current sizes of the discharge control. Thereby achieving different resolutions of the current detection ADC.

[0065] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention. Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0066] The BMS current detection circuit and method provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A BMS current detection circuit, characterized in that: The BMS current detection circuit includes a control module and a current sampling circuit module, and the control module and the current sampling circuit module are connected to the positive and negative terminals of the battery respectively after being connected; The current sampling circuit module includes a current sampler, a current detection unit, a discharge control unit and a charging control unit; the first input end and the second input end of the current sampler are connected to the control module, the output end of the current sampler is connected to the current detection unit, the first input end of the current sampler is also connected to the discharge control unit, and the control module is connected to the charging control unit; the current detection unit, the discharge control unit and the charging control unit are connected to each other; Among them, the current detection unit includes one or more current detection sub-circuits, the discharge control unit includes one or more discharge control sub-circuits, and the charging control unit includes one or more charging control sub-circuits; the number of the current detection sub-circuits, the discharge control sub-circuits and the charging control sub-circuits is the same; the control module controls the number of the current detection sub-circuits, the discharge control sub-circuits and the charging control sub-circuits that are turned on according to the current size in the BMS current detection circuit; a certain number of the current detection sub-circuits and the discharge control sub-circuits remain in the turned-on state.

2. The BMS current detection circuit according to claim 1, characterized in that: The control module includes a micro control unit or a battery sampling chip.

3. The BMS current detection circuit according to claim 2, characterized in that: The control module at least includes a charging control terminal, a discharging control terminal, a pulse signal output terminal, a current sampling positive terminal and a current sampling negative terminal; Among them, the first input end of the current sampler is connected to the discharge control end, the second output end of the current sampler is connected to the pulse signal output end, the current detection unit is connected to the current sampling positive end and the current sampling negative end, and the charging control unit is connected to the charging control end.

4. The BMS current detection circuit according to claim 1, characterized in that: Each current detection subcircuit in the current detection unit includes a current detection resistor, a positive-end current detection mixed resistor and a negative-end current detection mixed resistor, and the current detection resistor is connected in series with the positive-end current detection mixed resistor and the negative-end current detection mixed resistor to form the current detection subcircuit; Wherein, at least two current detection sub-circuits in the current detection unit are connected in parallel to form a first current detection group, and all other current detection sub-circuits in the current detection unit are connected in parallel to form a second current detection group.

5. The BMS current detection circuit according to claim 4, characterized in that: The current detection unit further comprises a positive-end current detection mixed signal switch and a negative-end current detection mixed signal switch; the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are connected to each current detection sub-circuit in the second current detection group; each current detection sub-circuit in the second current detection group is turned on according to the control of the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch; the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are connected to the output end of the current sampler, and the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are controlled by the current sampler; the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch are also connected to the control module; Among them, the positive-end current detection mixed signal switch is connected to the positive-end current detection mixed resistor in each current detection sub-circuit in the second current detection group, and the negative-end current detection mixed signal switch is connected to the negative-end current detection mixed resistor in each current detection sub-circuit in the second current detection group; the current detection sub-circuits in the first current detection group are not connected to the positive-end current detection mixed signal switch and the negative-end current detection mixed signal switch.

6. The BMS current detection circuit according to claim 5, characterized in that: The first current detection subcircuit and the second current detection subcircuit in the current detection unit are connected in parallel to form the first current detection group; The first current detection subcircuit and the second current detection subcircuit in the current detection unit are not connected to the first current detection mixed signal switch and the second current detection mixed signal switch, and the first current detection subcircuit and the second current detection subcircuit remain in a conducting state; The other current detection sub-circuits in the current detection unit are all connected to the first current detection mixed signal switch and the second current detection mixed signal switch, and the other current detection sub-circuits in the current detection unit are turned on according to the control of the positive end current detection mixed signal switch and the negative end current detection mixed signal switch.

7. The BMS current detection circuit according to claim 1, characterized in that: Each of the discharge control subcircuits in the discharge control unit includes a discharge control resistor and a discharge control switch, and the discharge control resistor is connected to the discharge control switch; each of the discharge control subcircuits is connected to the first input terminal of the current sampler; At least two of the discharge control subcircuits in the discharge control unit are connected in parallel to form a first discharge control circuit group, and all other discharge control subcircuits in the discharge control unit are connected in parallel to form a second discharge control circuit group.

8. The BMS current detection circuit according to claim 7, characterized in that: The first discharge control circuit group is connected to the first input end of the current sampler, and the second discharge control circuit group is connected to the output end of the current sampler; the first discharge control circuit group is connected to the first current detection group, and the second discharge control circuit group is connected to the second current detection group.

9. The BMS current detection circuit according to claim 1, characterized in that: Each of the charging control subcircuits in the charging control unit includes a driving resistor and a charging control switch, and the driving resistor is connected to the charging control switch; each of the charging control subcircuits is connected to the control module; Wherein, each of the charging control subcircuits are connected in parallel with each other; and the charging control subcircuit and the discharging control subcircuit are connected with each other.

10. A current detection method based on the BMS current detection circuit according to any one of claims 1 to 9, characterized in that: The current detection method comprises: The control module detects whether the current current value exceeds the threshold value. If the current current value does not exceed the threshold value, the current sampling circuit module enters the low current detection mode; if the current current value exceeds the threshold value, the current sampling circuit module enters the high current detection mode; When the current sampling circuit module is in the low current detection mode, only one or two current detection sub-circuits in the current detection unit of the current sampling circuit module are turned on, and only one or two discharge control sub-circuits or charging control sub-circuits in the discharge control unit package or the charging control unit of the current sampling circuit module are turned on; the current sampling circuit module performs current sampling of low current; When the current sampling circuit module is in the large current detection mode, the control module controls several current detection sub-circuits in the current detection unit to be turned on, and the control module controls several discharge control sub-circuits or charging control sub-circuits in the discharge control unit package or the charging control unit to be turned on; the current sampling circuit module performs current sampling of large currents.

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