Load current-limiting constant-current control circuit for BMS (Battery Management System)

Abstract

The utility model discloses a load current-limiting constant-current control circuit used for a BMS, and relates to the technical field of circuit protection. According to the novel circuit, the transistor Q1 is used for performing constant current and current limiting control to control the conducting state of the transistor Q2; the transistor Q2 plays a role in controlling the switch and is used for controlling the conducting state of the main loop; the current detection resistor RS1 plays a current detection role and is used for detecting the current of a main loop; the resistor R1 plays a role in current limiting, and the resistor R2 plays a role in bias voltage division and the like and is used for protecting the switch tube. The Zener diode ZD1 plays a role in switching protection and is used for protecting the switching tube when the input control voltage exceeds the limit of the switching tube.

Description

Technical Field

[0001] This utility model discloses a load current limiting constant current control circuit for BMS, which relates to the field of circuit protection technology. Background Technology

[0002] Currently, common BMS systems in the industry often experience a large instantaneous current due to the capacitance of the load itself when a load is connected, which frequently causes arcing and burns out the connectors.

[0003] The commonly used pre-discharge circuit in the industry currently involves connecting a current-limiting resistor in series. However, the output current varies greatly under different charge and voltage conditions, and it is impossible to determine whether the output load is capacitive, resistive, or in a short-circuit state, which can easily lead to high current and overheating.

[0004] Therefore, a load current limiting constant current control circuit for BMS is proposed to solve the above problems. Utility Model Content

[0005] This utility model addresses the problems of existing technologies by providing a load current limiting and constant current control circuit for a BMS. The technical solution adopted is as follows:

[0006] In a first aspect, a load current limiting constant current control circuit for a BMS, the circuit comprising:

[0007] The PRE-DSG circuit is connected to the collector of transistor Q1 through resistor R1.

[0008] The current sensing resistor RS1 is connected between the emitter and base of the transistor Q1;

[0009] Terminal B- is connected to one end of resistor R2 and the positive terminal of Zener diode ZD1 in sequence through current sensing resistor RS1. The other end of resistor R2 and the negative terminal of Zener diode ZD1 are simultaneously connected to the collector of transistor Q1.

[0010] The Zener diode ZD1 is connected to both ends of transistor Q2, and one end of transistor Q2 is connected to the D- terminal.

[0011] In some implementations, the circuit further includes an output voltage status detection circuit;

[0012] The output voltage state detection circuit is connected between transistor Q2 and the D- terminal.

[0013] In some implementations, the output voltage state detection circuit specifically includes a B- terminal and a D-_INT signal terminal.

[0014] The B- terminal is connected to the emitter of transistor Q3, and the emitter and base of transistor Q3 are connected by resistor R6.

[0015] The base of transistor Q3 is connected between transistor Q2 and the D- terminal through resistor R7;

[0016] The D-_INT signal terminal is connected to the collector of transistor Q3.

[0017] In some implementations, the circuit further includes resistors R3, R4, and R5, and a current-sensing resistor RS2;

[0018] The resistor R3 is connected between the collector of transistor Q1 and the other end of the resistor R2;

[0019] The resistor R5 is connected between the emitter and base of the transistor Q1, and the resistor R4 is connected between one end of the resistor R5 and one end of the current sensing resistor RS1.

[0020] The current sensing resistor RS2 is connected between one end of the resistor R4 and one end of the resistor R2.

[0021] In some implementations, transistors Q1, Q2, and Q3 are replaced with MOSFETs Q1, Q2, and Q3 in the circuit.

[0022] One or more embodiments of this utility model can bring at least the following beneficial effects:

[0023] This novel circuit uses transistor Q1 for constant current limiting control, controlling the conduction state of transistor Q2; transistor Q2 acts as a switch, controlling the conduction state of the main circuit; current-sensing resistor RS1 detects the current in the main circuit; resistor R1 limits the current, and resistor R2 acts as a bias voltage divider, protecting the switching transistor. The Zener diode ZD1 provides switch protection, protecting the switching transistor when the input control voltage exceeds its limit. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a structural diagram of a load current limiting constant current control circuit for BMS provided in this embodiment of the present invention;

[0026] Figure 2This is another embodiment of the load current limiting constant current control circuit for BMS provided by this utility model.

[0027] Figure 3 This is a second embodiment of the load current limiting constant current control circuit for BMS provided by this utility model. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] Example 1:

[0030] Figure 1 A structural diagram of a load current limiting constant current control circuit for a BMS is shown, as follows: Figure 1 As shown, this embodiment provides a load current limiting constant current control circuit for a BMS, including:

[0031] The PRE-DSG circuit is connected to the collector of transistor Q1 through resistor R1.

[0032] The current sensing resistor RS1 is connected between the emitter and base of the transistor Q1;

[0033] Terminal B- is connected to one end of resistor R2 and the positive terminal of Zener diode ZD1 in sequence through current sensing resistor RS1. The other end of resistor R2 and the negative terminal of Zener diode ZD1 are simultaneously connected to the collector of transistor Q1.

[0034] The Zener diode ZD1 is connected to both ends of transistor Q2, and one end of transistor Q2 is connected to the D- terminal.

[0035] In this novel circuit, transistor Q1 plays a constant current limiting control role, used to control the conduction state of transistor Q2.

[0036] Among them, transistor Q2 acts as a control switch to control the conduction state of the main circuit; current sensing resistor RS1 acts as a current sensor to detect the current in the main circuit; resistor R1 acts as a current limiter; and resistor R2 acts as a bias voltage divider to protect the switching transistor.

[0037] The Zener diode ZD1 serves as a switch protection device, used to protect the switch when the input control voltage exceeds the limit of the switch.

[0038] When the new circuit is initially powered on, the current in the current sensing resistor RS1 is 0, and transistors Q1 and Q2 are in the off state. At this time, if the control circuit of the PRE-DSG circuit is input with an on-state voltage, after current limiting and voltage division by resistors R1 and R2, transistor Q2 is forced to turn on, so that the main circuit is in the on state.

[0039] When a load is connected to the system, the current flowing through the current sensing resistor RS1 causes the VBE voltage of transistor Q1 to gradually increase. When the current exceeds the current limiting setting value, transistor Q1 enters the amplification state from the cutoff state, and the conduction current also gradually increases. After being current-limited and voltage-divided by resistor R1, the control input voltage of transistor Q2 decreases, causing transistor Q2 to switch from the conduction state to the amplification state. The conduction current of transistor Q2 decreases, and finally, both transistors Q1 and Q2 are in the amplification state, so that the main circuit current is limited to the design value.

[0040] This novel design incorporates a current-sensing resistor in the discharge circuit, using the voltage drop across the current-sensing resistor to drive the transistor and control the main circuit switch's conduction state. This prevents the instantaneous high-current arcing phenomenon that occurs when the BMS and load are connected, allowing the transistor to operate in an amplification state to achieve constant current control.

[0041] The specific parameters of the components in this novel circuit can be adjusted according to actual needs and are not limited to the values ​​in the example. Furthermore, the components in this novel circuit are not limited to discrete devices or integrated into one or more ICs. Moreover, this novel circuit is not limited to placement at the positive terminal, negative terminal, or discharge control; it can also be used for current limiting in pre-charge circuits. This novel circuit can be used in all product applications involving fuzzy current control in all loops, and is not limited to consumer electronics products.

[0042] Example 2:

[0043] Figure 2 Another implementation diagram of a load current limiting constant current control circuit for a BMS is shown, as follows: Figure 2 As shown, this embodiment provides a load current limiting constant current control circuit for BMS, and based on Embodiment 1, it also includes an output voltage status detection circuit.

[0044] The output voltage state detection circuit is connected between transistor Q2 and the D- terminal.

[0045] The output voltage state detection circuit specifically includes a B- terminal and a D-_INT signal terminal.

[0046] The B- terminal is connected to the emitter of transistor Q3, and the emitter and base of transistor Q3 are connected by resistor R6.

[0047] The base of transistor Q3 is connected between transistor Q2 and the D- terminal via resistor R7;

[0048] The D-_INT signal terminal is connected to the collector of transistor Q3.

[0049] Initially, the PRE-DSG circuit receives an input turn-on voltage, causing transistor Q2 to conduct, the main circuit to be on, the voltage at the D- terminal to be 0, and the signal at the D-_INT terminal to be a floating pull-up high level. When a capacitive load is connected, because the voltage of the load capacitor cannot change abruptly, the voltage at the D- terminal changes instantaneously from 0V to V+. The voltage at the D- terminal is then divided by resistors R6 and R7, driving transistor Q3 to conduct, causing the signal at the D-_INT terminal to be a low level. As the load capacitor is charged by a constant current, its voltage gradually increases, meaning the voltage at the D- terminal gradually decreases. When the set threshold is reached, transistor Q3 is turned off, and the signal at the D-_INT terminal becomes a floating pull-up high level.

[0050] When this new circuit is working, the time of level change at the D-_INT terminal is recorded. The size of the load capacitance and whether the load is short-circuited can be calculated by the formula C=(I*dT) / dU.

[0051] Furthermore, the detection range of the voltage at the D- terminal can be adjusted by adjusting the resistance values ​​of resistors R6 and R7.

[0052] The implementation of this novel circuit can be applied to different scenarios requiring load preload and load short-circuit detection, such as BMS systems, mobile power systems, consumer electronics products, etc., as needed.

[0053] Example 3:

[0054] Figure 3 Another implementation diagram of a load current limiting constant current control circuit for a BMS is shown, as follows: Figure 3 As shown, this embodiment provides a load current limiting constant current control circuit for BMS. Based on embodiment two, the circuit further includes resistors R3, R4, R5 and current sensing resistor RS2.

[0055] The resistor R3 is connected between the collector of transistor Q1 and the other end of the resistor R2;

[0056] The resistor R5 is connected between the emitter and base of the transistor Q1, and the resistor R4 is connected between one end of the resistor R5 and one end of the current sensing resistor RS1.

[0057] The current sensing resistor RS2 is connected between one end of the resistor R4 and one end of the resistor R2.

[0058] In the circuit described above, transistors Q1, Q2, and Q3 can be replaced with MOSFETs Q1, Q2, and Q3.

[0059] In this embodiment, resistors R3, R4, R5, and current sensing resistor RS2 are added as current-limiting voltage divider resistors to better protect the switching transistor.

[0060] When the system enters the constant current amplification state, if transistor Q1 fails and cannot control transistor Q2 to maintain the amplification state, the current flowing through current sensing resistors RS1 and RS2 will continue to increase until a certain threshold is reached, at which point the gate-source voltage of transistor Q2 will be unable to turn on transistor Q2 or maintain transistor Q2 in an amplification state range.

[0061] If the fault amplifies and transistor Q2 fails and shoots through, this new circuit can be regarded as a resistor current-limiting circuit, which can protect the system safety to a certain extent.

[0062] The circuit in this embodiment is designed to be fault-tolerant, reducing system safety failures when some hardware is damaged.

[0063] In the several embodiments provided in this utility model, it should be understood that the disclosed system and method can also be implemented in other ways. The system and method embodiments described above are merely illustrative.

[0064] It should be noted that, in this document, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. 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.

[0065] Although the embodiments disclosed in this utility model are as described above, the content described is merely for the purpose of facilitating understanding of this utility model and is not intended to limit this utility model. Any person skilled in the art to which this utility model pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this utility model, but the patent protection scope of this utility model shall still be determined by the scope defined in the appended claims.

Claims

1. A load current limiting constant current control circuit for a BMS, characterized in that, The circuit includes: The PRE-DSG circuit is connected to the collector of transistor Q1 through resistor R1. The current sensing resistor RS1 is connected between the emitter and base of the transistor Q1; Terminal B- is connected to one end of resistor R2 and the positive terminal of Zener diode ZD1 in sequence through current sensing resistor RS1. The other end of resistor R2 and the negative terminal of Zener diode ZD1 are simultaneously connected to the collector of transistor Q1. The Zener diode ZD1 is connected to both ends of transistor Q2, and one end of transistor Q2 is connected to the D- terminal.

2. The load current limiting constant current control circuit for BMS according to claim 1, characterized in that, The circuit also includes an output voltage status detection circuit; The output voltage state detection circuit is connected between transistor Q2 and the D- terminal.

3. The load current limiting constant current control circuit for BMS according to claim 2, characterized in that, The output voltage state detection circuit specifically includes a B- terminal and a D-_INT signal terminal. The B- terminal is connected to the emitter of transistor Q3, and the emitter and base of transistor Q3 are connected by resistor R6. The base of transistor Q3 is connected between transistor Q2 and the D- terminal through resistor R7; The D-_INT signal terminal is connected to the collector of transistor Q3.

4. The load current limiting constant current control circuit for BMS according to claim 3, characterized in that, The circuit also includes resistors R3, R4, and R5, and a current-sensing resistor RS2; The resistor R3 is connected between the collector of transistor Q1 and the other end of the resistor R2; The resistor R5 is connected between the emitter and base of the transistor Q1, and the resistor R4 is connected between one end of the resistor R5 and one end of the current sensing resistor RS1. The current sensing resistor RS2 is connected between one end of the resistor R4 and one end of the resistor R2.

5. The load current limiting constant current control circuit for BMS according to claim 3, characterized in that, In the circuit described, transistors Q1, Q2, and Q3 are replaced with MOSFETs Q1, Q2, and Q3.

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