Short-circuit protection circuit of battery and electric equipment

Abstract

The invention relates to the technical field of battery overcurrent protection, and discloses a short-circuit protection circuit of a battery and electric equipment. The short-circuit protection circuit is used for immediately disconnecting a battery discharge loop when the battery discharge loop is short-circuited, and comprises a self-locking module; the self-locking module comprises a short circuit signal locking unit provided with a switch tube K1, a short circuit response unit provided with a switch tube K2 and a loop closing unit provided with a switch tube K3. A hardware protection mode which is formed by combining a plurality of switch tubes and can realize signal self-locking is adopted, the response time is short, the power control switch tubes can be quickly closed when a load end is short-circuited, and thermal breakdown damage caused by continuous overload is avoided; and the circuit also has an unlocking function, so that the defect that the load end cannot be continuously used after short circuit is triggered by mistake is avoided, and the error tolerance rate of a user is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of short-circuit protection of batteries, and in particular to a short-circuit protection circuit of a battery and an electrical device. Background Art

[0002] In the field of new energy, users are gradually enriching the use environment and methods of products. Conventional battery protection solutions only detect and judge the short circuit of the battery itself, but lack short circuit detection and protection for newly added functional interfaces (such as motor drive, charger heating film, etc.); therefore, once the input source current is large, it is easy to cause thermal breakdown of the power control switch tube of the battery discharge circuit, so short circuit detection for use scenarios with large input source current is particularly important. The following solutions are generally used in current technology:

[0003] Solution 1: Increase the overcurrent capacity of the power control switch tube to withstand the high current impact at the moment of short circuit until the input source triggers the protection shutdown; this method is costly and has the risk of impact damage to the power control switch tube, and the input source protection time is also uncertain.

[0004] Solution 2: Adopt MCU (Microcontroller Unit) sampling method, use MCU to sample short-circuit current and shut down output for protection when short circuit is detected; however, since MCU sampling delay is slow, generally in milliseconds, when a short circuit occurs, the power control switch tube needs to be able to withstand milliseconds until the MCU starts protection action. This method has high requirements for the power control switch tube or requires multiple power control switch tubes to be connected in parallel to share the pressure, thereby increasing the circuit cost.

[0005] Solution 3: Use dual op amps for current and short-circuit detection. This method has high detection accuracy, but the corresponding cost is also relatively high. In addition, this solution does not take into account the recovery of working conditions after the short-circuit protection is triggered. For example, the positive and negative poles of the charger heating film are accidentally short-circuited by the user, but in fact the short-circuit phenomenon is not caused by the quality problem of the charger heating film itself, that is, the charger heating film can still be used normally. However, in the prior art, once the short-circuit phenomenon is triggered by the user's mistake, after the short-circuit protection is triggered, the charger heating film cannot be used again, even if the positive and negative poles of the charger heating film are no longer short-circuited (that is, the charger heating film can be used normally). Therefore, the user is required not to make mistakes, and the error tolerance rate is low.

[0006] In summary, there is an urgent need in the art for a short-circuit protection circuit that can quickly shut down the power control switch tube when a short circuit occurs at the load end, and can restore normal operation of the load end after the short-circuit protection function is triggered.

[0007] The above information is presented as background information only to assist with understanding the present disclosure and no determination or admission is made as to whether any of the above may be used as prior art with respect to the present disclosure. Summary of the invention

[0008] The object of the present invention is to provide a short-circuit protection circuit for a battery and an electrical device, so as to solve or at least partially solve the technical problems existing in the prior art.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a short-circuit protection circuit of a battery, which is used to immediately disconnect the battery discharge circuit when a short circuit occurs in the battery discharge circuit, and includes a self-locking module;

[0011] The self-locking module includes a short-circuit signal locking unit provided with a switch tube K1, a short-circuit response unit provided with a switch tube K2, and a loop closing unit provided with a switch tube K3; the output end of the short-circuit response unit is electrically connected to the input end of the loop closing unit and the input end of the short-circuit signal locking unit respectively, the output end of the loop closing unit is electrically connected to the control end of the power control switch tube, and the output end of the short-circuit signal locking unit is electrically connected to the input end of the short-circuit response unit;

[0012] When the battery discharge circuit works normally, the switch tube K1, the switch tube K2 and the switch tube K3 are all disconnected or not conducting; when a short circuit occurs in the battery discharge circuit, a low-level signal is connected to the input end of the short-circuit response unit, the switch tube K2 is turned on, and the output end of the short-circuit response unit outputs a high-level signal. Once a high-level signal is connected to the input end of the short-circuit signal locking unit, the switch tube K1 is turned on, and the output end of the short-circuit signal locking unit is pulled down to a low-level signal, thereby locking the switch state of the switch tube K2 to the conducting state; and when a high-level signal is connected to the input end of the loop closing unit, the switch tube K3 is turned on, and the control end of the power control switch tube is pulled down to a low-level signal, so that the control power control switch tube is disconnected or not conducting;

[0013] The self-locking module is also electrically connected to an unlocking module, which can be controlled to pull down the input end of the short-circuit signal locking unit to a low-level signal after a short circuit occurs in the battery discharge circuit, so that the switch tube K1 is disconnected or not turned on.

[0014] Optionally, the short-circuit signal locking unit further includes a resistor R7; the short-circuit response unit further includes a resistor R5, a resistor R14 and a resistor R9; the first end of the resistor R14 is the input end of the short-circuit response unit, and the first end of the resistor R9 is the output end of the short-circuit response unit; wherein the switch tube K1 is an NMOS tube or an NPN transistor, and the switch tube K2 is a PMOS tube or a PNP transistor;

[0015] A first end of the resistor R14 is electrically connected to the positive terminal of the switch tube K1, a second end of the resistor R14 is electrically connected to the control end of the switch tube K2, the positive terminal of the switch tube K2 is electrically connected to the working power supply VCC of the short-circuit protection circuit, the negative terminal of the switch tube K2 is electrically connected to the first end of the resistor R9, and the second end of the resistor R9 is grounded; a resistor R5 is also electrically connected between the positive terminal of the switch tube K2 and the control end of the switch tube K2;

[0016] The control end of the switch tube K1 is electrically connected to the first end of the resistor R7, the second end of the resistor R7 is electrically connected to the first end of the resistor R9, and the negative terminal of the switch tube K1 is grounded.

[0017] Optionally, the short-circuit response unit also includes a resistor R8 and a capacitor C5; the negative terminal of the switch tube K2 is electrically connected to the first end of the resistor R8, and the second end of the resistor R8 is electrically connected to the first end of the resistor R9; the positive electrode of the capacitor C5 is electrically connected to the first end of the resistor R9, and the negative electrode of the capacitor C5 is grounded.

[0018] Optionally, the loop closing unit includes a capacitor C6, a resistor R10 and a switch tube K3;

[0019] The first end of the resistor R10 is electrically connected to the first end of the resistor R9 and the positive electrode of the capacitor C6 respectively, the second end of the resistor R10 is electrically connected to the control end of the switch tube K3, the positive terminal of the switch tube K3 is electrically connected to the control end of the power control switch tube, and the negative electrode of C6 and the negative terminal of the switch tube K3 are both grounded;

[0020] The switch tube K3 is an NMOS tube or an NPN transistor.

[0021] Optionally, the short-circuit response unit is electrically connected to a short-circuit detection circuit;

[0022] The short-circuit detection circuit includes a current detection chip U2 for sampling the voltage drop across the current-sensing resistor in the battery discharge circuit, and amplifying the sampled voltage drop according to a preset amplification factor and then outputting it; the output end of the current detection chip U2 is electrically connected to a short-circuit identification unit circuit;

[0023] The short circuit identification unit circuit includes a resistor R3, a resistor R4, a capacitor C4 and a controllable precision voltage-stabilizing source U1; the output end of the current detection chip U2 is electrically connected to the first end of the resistor R4, the second end of R4 is grounded, the first end of the resistor R3 is electrically connected to the positive electrode of the capacitor C4 and the reference end of the controllable precision voltage-stabilizing source U1 respectively, the second end of the resistor R3 is electrically connected to the first end of the resistor R4, the positive electrode of the controllable precision voltage-stabilizing source U1 is electrically connected to the input end of the short circuit response unit, and the negative electrode of the controllable precision voltage-stabilizing source U1 is grounded;

[0024] When a short circuit occurs in the battery discharge circuit, the voltage output by the current detection chip U2 is greater than or equal to a preset threshold voltage, the controllable precision voltage regulator U1 is turned on, and the input end of the short circuit response unit is connected to a low level signal.

[0025] Optionally, the current detection chip U2 has a built-in differential amplifier and an NPN transistor;

[0026] The positive terminal of the current-sensing resistor is electrically connected to the first end of the resistor R1, and the negative terminal of the current-sensing resistor is electrically connected to the first end of the resistor R2, and the resistor R1 and the resistor R2 are resistors with the same resistance value; the second end of the resistor R1 is electrically connected to the positive input end of the differential amplifier and the positive electrode of the capacitor C1, respectively, and the second end of the resistor R2 is electrically connected to the negative input end of the differential amplifier and the negative electrode of the capacitor C1, respectively; the output end of the differential amplifier is electrically connected to the base of the NPN transistor, the collector of the NPN transistor is electrically connected to the positive input end of the differential amplifier, and the emitter of the NPN transistor is the output end of the current detection chip U2; the output end of the current detection chip U2 is also electrically connected to the positive electrode of the capacitor C3, and the negative electrode of the capacitor C3 is grounded;

[0027] The voltage output by the current detection chip U2 = (resistance value of R4 / resistance value of R2)*voltage difference between the two input terminals of the differential amplifier.

[0028] Optionally, the unlocking module includes a resistor R13, a capacitor C7, a resistor R11 and a switch tube K5;

[0029] The first end of the resistor R13 is electrically connected to the unlocking signal output end of the MCU of the battery and the positive electrode of the capacitor C7, and the unlocking signal output end of the MCU is used to pull down the input end of the short-circuit signal locking unit to a low-level signal; the second end of the resistor R13 is electrically connected to the first end of the resistor R11 and the control end of the switch tube K5, the negative electrode of the capacitor C7 and the second end of the resistor R11 are grounded, the positive terminal of the switch tube K5 is electrically connected to the output end of the short-circuit response unit, and the negative terminal of the switch tube K5 is grounded;

[0030] The switch tube K5 is an NMOS tube or an NPN transistor.

[0031] Optionally, the self-locking module also short-circuits a notification unit circuit;

[0032] The short-circuit notification unit circuit includes a resistor R15, a switch tube K4, a resistor R16 and a resistor R12; the first end of the resistor R15 is electrically connected to the control end of the switch tube K3 and the control end of the switch tube K4, the second end of the resistor R15 and the negative terminal of the switch tube K4 are both grounded, the first end of the resistor R16 is electrically connected to the working power supply VCC, the second end of the resistor R16 is electrically connected to the positive terminal of the switch tube K4 and the first end of the resistor R12, and the second end of the resistor R12 is electrically connected to the short-circuit signal monitoring end of the MCU of the battery;

[0033] The switch tube K4 is an NMOS tube or an NPN transistor.

[0034] Optionally, the short-circuit response unit is electrically connected to a short-circuit detection circuit;

[0035] The short-circuit detection circuit includes a current detection chip U2 for sampling the voltage drop across the current-sensing resistor in the battery discharge circuit, and amplifying the sampled voltage drop according to a preset amplification factor and then outputting it; the output end of the current detection chip U2 is electrically connected to a short-circuit identification unit circuit;

[0036] The short circuit identification unit circuit includes a resistor R3, a resistor R4, a sliding resistor RU and a voltage comparator U1A; wherein the voltage comparator U1A adopts an LM311 voltage comparator;

[0037] The first pin of the voltage comparator U1A is grounded, the second pin of the voltage comparator U1A is electrically connected to the first end of the resistor R3, the third pin of the voltage comparator U1A is electrically connected to the sliding adjustment end of the sliding rheostat RU, the fourth pin of the voltage comparator U1A is grounded, the seventh pin of the voltage comparator U1A is electrically connected to the input end of the short-circuit response unit, and the eighth pin of the voltage comparator U1A is electrically connected to the working power supply VCC of the short-circuit protection circuit; the second end of the resistor R3 is electrically connected to the output end of the current detection chip U2 and the first end of the resistor R4, respectively, the second end of R4 is grounded, the first end of the sliding rheostat RU is electrically connected to the working power supply VCC, and the second end of the sliding rheostat RU is grounded;

[0038] When a short circuit occurs in the battery discharge circuit, the voltage output by the current detection chip U2 is greater than or equal to a preset threshold voltage, and the seventh pin of the voltage comparator U1A outputs a low level signal.

[0039] In a second aspect, the present invention further provides an electrical device, including a battery discharge circuit, wherein the battery discharge circuit is provided with a current sensing resistor and a power control switch tube for controlling the on / off of the battery discharge circuit, and also includes a battery short-circuit protection circuit as described above;

[0040] The input end of the short-circuit response unit is electrically connected to a short-circuit detection circuit for sampling a voltage drop across a current-sensing resistor; the short-circuit detection circuit is also used to output a low-level signal to the short-circuit response unit when a short circuit occurs in a battery discharge circuit.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The short-circuit protection circuit in the present invention adopts a hardware protection method that can realize signal self-locking formed by a combination of multiple switch tubes. There is no delay and the response time is fast. The power control switch tube can be quickly turned off when the load end is short-circuited to avoid thermal breakdown damage due to continuous overload, and there is no need to use a multi-channel operational amplifier circuit to increase costs; the circuit also has an additional unlocking function, so that it can more flexibly deal with various working conditions after triggering the short-circuit protection, especially avoiding the disadvantage that the load end cannot be used anymore after false triggering, thereby increasing the user's error tolerance rate.

[0043] The present invention has other features and advantages, which will be apparent from or will be described in detail in the accompanying drawings and the following detailed description incorporated herein, which together serve to explain the specific principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 The invention discloses a circuit structure schematic diagram of a short-circuit protection circuit for a battery.

[0046] Figure 2 yes Figure 1 Schematic diagram of the internal circuit structure of the current detection chip U2.

[0047] Figure 3 It is a circuit structure principle diagram of a short circuit detection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0049] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0050] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0051] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0052] In the present application, terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0053] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0054] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0055] In the description of the embodiments of the present application, space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the referred device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0056] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms such as "install", "connect", "connect", "fix", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For technicians in the technical field to which the present application belongs, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0057] Embodiment 1:

[0058] See also Figure 1 , Figure 1 It is a circuit structure principle diagram of a short-circuit protection circuit of a battery provided by an embodiment of the present invention. The short-circuit protection circuit is used to immediately disconnect the battery discharge circuit when a short circuit occurs in the battery discharge circuit.

[0059] The short-circuit protection circuit specifically includes:

[0060] A short circuit detection circuit is used to sample the voltage drop across the current-sensing resistor in the battery discharge circuit; specifically, the short circuit detection circuit can identify whether a short circuit occurs in the battery discharge circuit based on the sampled voltage drop across the current-sensing resistor, and when a short circuit occurs in the battery discharge circuit, an output terminal of the short circuit detection circuit outputs a low-level signal;

[0061] A self-locking module, electrically connected to the output end of the short-circuit detection circuit, used to immediately disconnect or non-conduct the power control switch tube when a short circuit occurs in the battery discharge circuit;

[0062] Specifically, the self-locking module includes a short-circuit signal locking unit provided with a switch tube K1, a short-circuit response unit provided with a switch tube K2, and a circuit closing unit provided with a switch tube K3;

[0063] The output end of the short circuit response unit is electrically connected to the input end of the loop closing unit and the input end of the short circuit signal locking unit respectively, the output end of the loop closing unit is electrically connected to the control end of the power control switch tube, and the output end of the short circuit signal locking unit is electrically connected to the input end of the short circuit response unit;

[0064] When the battery discharge circuit works normally, the switch tube K1, the switch tube K2 and the switch tube K3 are all disconnected or not conducting;

[0065] When a short circuit occurs in the battery discharge circuit, a low-level signal is connected to the input end of the short-circuit response unit, the switch tube K2 is turned on, and the output end of the short-circuit response unit outputs a high-level signal. Once a high-level signal is connected to the input end of the short-circuit signal locking unit, the switch tube K1 is turned on, and the output end of the short-circuit signal locking unit is pulled down to a low-level signal, thereby locking the switch state of the switch tube K2 to the on state; and when a high-level signal is connected to the input end of the loop closing unit, the switch tube K3 is turned on, and the control end of the power control switch tube is pulled down to a low-level signal, so that the control power control switch tube is disconnected or not turned on.

[0066] The above short-circuit protection circuit adopts a hardware protection method that can realize signal self-locking formed by a combination of multiple switch tubes. It has no delay and fast response time. It can quickly turn off the power control switch tube when a short circuit occurs in the battery discharge circuit to avoid thermal breakdown damage due to continuous overload. There is no need to use a multi-channel operational amplifier circuit, which effectively reduces the cost.

[0067] In addition, the circuit also has an additional unlocking function, which can more flexibly deal with various working conditions after triggering the short-circuit protection, especially avoiding the disadvantage that the load end cannot be used after false triggering, and increasing the user's error tolerance rate.

[0068] Specifically, the self-locking module is also electrically connected to an unlocking module, which can be controlled to pull down the input end of the short-circuit signal locking unit to a low-level signal after a short circuit occurs in the battery discharge circuit, so that the switch tube K1 is disconnected or not turned on.

[0069] More specifically, the unlocking module includes a resistor R13, a capacitor C7, a resistor R11 and a switch tube K5;

[0070] The first end of the resistor R13 is electrically connected to the unlocking signal output end of the MCU of the battery and the positive electrode of the capacitor C7, and the unlocking signal output end of the MCU is used to pull down the input end of the short-circuit signal locking unit to a low-level signal; the second end of the resistor R13 is electrically connected to the first end of the resistor R11 and the control end of the switch tube K5, the negative electrode of the capacitor C7 and the second end of the resistor R11 are grounded, the positive terminal of the switch tube K5 is electrically connected to the output end of the short-circuit response unit, and the negative terminal of the switch tube K5 is grounded;

[0071] The switch tube K5 is an NMOS tube or an NPN transistor.

[0072] The short circuit protection circuit provided in this embodiment is protected by hardware and uses software to determine whether to recover; Figure 1 As shown, when a short circuit occurs in the battery discharge circuit, the short circuit response unit outputs a short circuit signal (i.e., a high level signal), the switch tube K3 is turned on, and the power control switch tube in the battery discharge circuit is turned off. At the same time, the short circuit signal is also sent to the MCU end through the short circuit notification unit circuit. In this embodiment, after the short circuit signal is connected to the short circuit notification unit circuit, the short circuit notification unit circuit will send a low level signal to the short circuit signal monitoring end of the MCU, so that the MCU knows that a short circuit has occurred in the battery discharge circuit.

[0073] Furthermore, the MCU determines whether the battery discharge circuit has reached the condition for releasing the short-circuit protection (i.e., the short-circuit phenomenon in the battery discharge circuit no longer exists and the battery discharge circuit is in a working condition capable of normal operation). When the condition is met, the MCU sends a clear signal to the switch tube K5 to release the self-locking module and restart a new round of detection.

[0074] Specifically, the low-level notification method used in this embodiment is to notify the MCU; the short-circuit notification unit circuit is implemented as follows:

[0075] The short-circuit notification unit circuit includes a resistor R15, a switch tube K4, a resistor R16 and a resistor R12; the first end of the resistor R15 is electrically connected to the control end of the switch tube K3 and the control end of the switch tube K4 respectively, the second end of the resistor R15 and the negative terminal of the switch tube K4 are both grounded, the first end of the resistor R16 is electrically connected to the working power supply VCC, the second end of the resistor R16 is electrically connected to the positive terminal of the switch tube K4 and the first end of the resistor R12 respectively, and the second end of the resistor R12 is electrically connected to the short-circuit signal monitoring end of the MCU of the battery;

[0076] The switch tube K4 is an NMOS tube or an NPN transistor.

[0077] The short-circuit protection circuit provided in this embodiment captures the instantaneous generation of the short-circuit signal and self-locks to complete stable protection; the specific circuit implementation is as follows:

[0078] The short-circuit signal locking unit further includes a resistor R7; the short-circuit response unit further includes a resistor R5, a resistor R14 and a resistor R9; the first end of the resistor R14 is the input end of the short-circuit response unit, and the first end of the resistor R9 is the output end of the short-circuit response unit; wherein the switch tube K1 is an NMOS tube or an NPN transistor, and the switch tube K2 is a PMOS tube or a PNP transistor;

[0079] A first end of the resistor R14 is electrically connected to the positive terminal of the switch tube K1, a second end of the resistor R14 is electrically connected to the control end of the switch tube K2, the positive terminal of the switch tube K2 is electrically connected to the working power supply VCC of the short-circuit protection circuit, the negative terminal of the switch tube K2 is electrically connected to the first end of the resistor R9, and the second end of the resistor R9 is grounded; a resistor R5 is also electrically connected between the positive terminal of the switch tube K2 and the control end of the switch tube K2;

[0080] The control end of the switch tube K1 is electrically connected to the first end of the resistor R7, the second end of the resistor R7 is electrically connected to the first end of the resistor R9, and the negative terminal of the switch tube K1 is grounded.

[0081] The short circuit response unit also includes a resistor R8 and a capacitor C5; the negative terminal of the switch tube K2 is electrically connected to the first end of the resistor R8, and the second end of the resistor R8 is electrically connected to the first end of the resistor R9; the positive electrode of the capacitor C5 is electrically connected to the first end of the resistor R9, and the negative electrode of the capacitor C5 is grounded.

[0082] The loop closing unit includes a capacitor C6, a resistor R10 and a switch tube K3;

[0083] The first end of the resistor R10 is electrically connected to the first end of the resistor R9 and the positive electrode of the capacitor C6 respectively, the second end of the resistor R10 is electrically connected to the control end of the switch tube K3, the positive terminal of the switch tube K3 is electrically connected to the control end of the power control switch tube, and the negative electrode of C6 and the negative terminal of the switch tube K3 are both grounded;

[0084] The switch tube K3 is an NMOS tube or an NPN transistor.

[0085] Specifically, the short-circuit detection circuit includes a current detection chip U2 for sampling the voltage drop across the current-sensing resistor in the battery discharge circuit, and amplifying the sampled voltage drop according to a preset amplification factor and then outputting it; the output end of the current detection chip U2 is electrically connected to a short-circuit identification unit circuit;

[0086] The short circuit identification unit circuit includes a resistor R3, a resistor R4, a capacitor C4 and a controllable precision voltage-stabilizing source U1; the output end of the current detection chip U2 is electrically connected to the first end of the resistor R4, the second end of R4 is grounded, the first end of the resistor R3 is electrically connected to the positive electrode of the capacitor C4 and the reference end of the controllable precision voltage-stabilizing source U1 respectively, the second end of the resistor R3 is electrically connected to the first end of the resistor R4, the positive electrode of the controllable precision voltage-stabilizing source U1 is electrically connected to the input end of the short circuit response unit, and the negative electrode of the controllable precision voltage-stabilizing source U1 is grounded;

[0087] When a short circuit occurs in the battery discharge circuit, the voltage output by the current detection chip U2 is greater than or equal to the preset threshold voltage, the controllable precision voltage regulator U1 is turned on, and the input end of the short circuit response unit is connected to a low level signal.

[0088] Exemplarily, the controllable precision voltage regulator U1 uses a transistor voltage regulator chip of model TL431;

[0089] Assuming that the current sensing resistor is 4mR, when the current threshold reaching the short-circuit protection condition is 2.5÷20÷0.004=31.25A, the controllable precision voltage regulator U1 is turned on, and the positive electrode of the controllable precision voltage regulator U1 ( Figure 1 Pin 1) in the short circuit response unit is pulled down to a low level, and the input end of the short circuit response unit is connected to a low level signal.

[0090] For details, please refer to Figure 2 , Figure 2 yes Figure 1 The internal circuit structure schematic diagram of the current detection chip U2 in the embodiment; In the present embodiment, the current detection chip U2 adopts the current detection chip model WA142 provided by Taiwan Weibo Company, and the current detection chip has a built-in differential amplifier and an NPN transistor;

[0091] The positive terminal of the current-sense resistor is electrically connected to the first end of the resistor R1, and the negative terminal of the current-sense resistor is electrically connected to the first end of the resistor R2. The resistors R1 and R2 have the same resistance value. The second end of the resistor R1 is electrically connected to the positive input terminal ( Figure 1 The pin 3 of U2 in the circuit and the positive electrode of the capacitor C1, and the second end of the resistor R2 are electrically connected to the negative input terminal of the differential amplifier ( Figure 1 The output end of the differential amplifier is electrically connected to the base of the NPN transistor, the collector of the NPN transistor is electrically connected to the positive input end of the differential amplifier, and the emitter of the NPN transistor is the output end of the current detection chip U2 ( Figure 1 The output end of the current detection chip U2 is also electrically connected to the positive electrode of the capacitor C3, and the negative electrode of the capacitor C3 is grounded;

[0092] For the wiring method of other pins of the current detection chip U2, please refer to Figure 1 As shown; that is, pin 2 of the current detection chip U2 is a GND pin, which is grounded; pin 5 of the current detection chip U2 is a VCC pin, which is connected to a +3.3V power supply, and a capacitor C2 is also electrically connected between the VCC pin and the low signal;

[0093] The voltage output by the current detection chip U2 = (resistance value of R4 / resistance value of R2) * voltage difference between the two input terminals of the differential amplifier; therefore, the resistance ratio of resistor R4 and resistor R2 can be set accordingly according to the conduction condition of U1 to provide a corresponding voltage to the reference terminal of U1 to make U1 conduct.

[0094] As an optional implementation, the short circuit identification unit circuit can also be implemented by the following circuit structure, as follows:

[0095] Please refer to Figure 3 , Figure 3 is a circuit structure principle diagram of a short circuit detection circuit provided by an embodiment of the present invention;

[0096] The short circuit identification unit circuit includes a resistor R3, a resistor R4, a sliding rheostat RU and a voltage comparator U1A; wherein the voltage comparator U1A adopts an LM311 voltage comparator;

[0097] The first pin of the voltage comparator U1A is grounded, the second pin of the voltage comparator U1A is electrically connected to the first end of the resistor R3, the third pin of the voltage comparator U1A is electrically connected to the sliding adjustment end of the sliding rheostat RU, the fourth pin of the voltage comparator U1A is grounded, the seventh pin of the voltage comparator U1A is electrically connected to the input end of the short-circuit response unit, and the eighth pin of the voltage comparator U1A is electrically connected to the working power supply VCC of the short-circuit protection circuit; the second end of the resistor R3 is electrically connected to the output end of the current detection chip U2 and the first end of the resistor R4, respectively, the second end of R4 is grounded, the first end of the sliding rheostat RU is electrically connected to the working power supply VCC, and the second end of the sliding rheostat RU is grounded;

[0098] When a short circuit occurs in the battery discharge circuit, the voltage output by the current detection chip U2 is greater than or equal to a preset threshold voltage, and the seventh pin of the voltage comparator U1A outputs a low level signal.

[0099] For example, when the voltage output after amplification by the current detection chip U2 is applied to pin 2 of U1A, pin 2 is compared with pin 3. If pin 2 is greater than pin 3, a short-circuit signal is output immediately; pin 3 is an adjustable voltage comparison point, and the voltage entering pin 3 is adjusted by the sliding resistor RU.

[0100] like Figure 3 As shown, if the short-circuit identification unit circuit is implemented by a voltage comparator, the response speed of the short-circuit signal will be faster.

[0101] In summary, the short-circuit protection circuit provided in this embodiment can quickly shut down the power switch tube when the load end (battery discharge circuit) is short-circuited, so as to prevent it from being damaged by thermal breakdown due to continuous overload; moreover, the circuit does not need to add additional power tubes, the cost is low, and the circuit is simple; the hardware protection method is adopted, the response time is fast, and there is no need to use a multi-channel operational amplifier circuit to increase the cost;

[0102] This circuit also has an unlocking function, which is controlled by the MCU. It can more flexibly deal with various working conditions after protection, avoiding the disadvantage of being unusable due to false triggering. At the same time, it can more flexibly judge whether it can be used again after triggering a short circuit, increasing the user's error tolerance rate.

[0103] Embodiment 2:

[0104] Based on the same concept, this embodiment provides an electrical device, including a battery discharge circuit, in which a current sensing resistor and a power control switch tube for controlling the on / off of the battery discharge circuit are provided, and also includes a short-circuit protection circuit of a battery as described in Embodiment 1;

[0105] The input end of the short-circuit response unit is electrically connected to a short-circuit detection circuit for sampling the voltage drop across the current-sensing resistor; the short-circuit detection circuit is also used to output a low-level signal to the short-circuit response unit when a short circuit occurs in the battery discharge circuit.

[0106] Since the short-circuit protection circuit of the battery has been described in detail in the first embodiment, it will not be described again in this embodiment.

[0107] This electrical equipment can quickly shut down the power switch tube when a short circuit occurs at the load end, with a fast response time, thus avoiding thermal breakdown damage due to continuous overload. In addition, its short-circuit protection circuit is also equipped with an unlocking function controlled by the MCU, which can more flexibly cope with various working conditions after protection, avoiding the disadvantage of being unusable due to false triggering, and increasing the user's error tolerance rate.

[0108] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A short-circuit protection circuit for a battery, used to immediately disconnect the battery discharge circuit when a short circuit occurs in the battery discharge circuit, characterized in that: Including self-locking module; The self-locking module includes a short-circuit signal locking unit provided with a switch tube K1, a short-circuit response unit provided with a switch tube K2, and a loop closing unit provided with a switch tube K3; the output end of the short-circuit response unit is electrically connected to the input end of the loop closing unit and the input end of the short-circuit signal locking unit respectively, the output end of the loop closing unit is electrically connected to the control end of the power control switch tube, and the output end of the short-circuit signal locking unit is electrically connected to the input end of the short-circuit response unit; When the battery discharge circuit works normally, the switch tube K1, the switch tube K2 and the switch tube K3 are all disconnected or not conducting; when a short circuit occurs in the battery discharge circuit, a low-level signal is connected to the input end of the short-circuit response unit, the switch tube K2 is turned on, and the output end of the short-circuit response unit outputs a high-level signal. Once a high-level signal is connected to the input end of the short-circuit signal locking unit, the switch tube K1 is turned on, and the output end of the short-circuit signal locking unit is pulled down to a low-level signal, thereby locking the switch state of the switch tube K2 to the conducting state; and when a high-level signal is connected to the input end of the loop closing unit, the switch tube K3 is turned on, and the control end of the power control switch tube is pulled down to a low-level signal, so that the control power control switch tube is disconnected or not conducting; The self-locking module is also electrically connected to an unlocking module, which can be controlled to pull down the input end of the short-circuit signal locking unit to a low-level signal after a short circuit occurs in the battery discharge circuit, so that the switch tube K1 is disconnected or not turned on.

2. A short circuit protection circuit for a battery according to claim 1, characterized in that: The short-circuit signal locking unit further includes a resistor R7; the short-circuit response unit further includes a resistor R5, a resistor R14 and a resistor R9; the first end of the resistor R14 is the input end of the short-circuit response unit, and the first end of the resistor R9 is the output end of the short-circuit response unit; wherein the switch tube K1 is an NMOS tube or an NPN transistor, and the switch tube K2 is a PMOS tube or a PNP transistor; A first end of the resistor R14 is electrically connected to the positive terminal of the switch tube K1, a second end of the resistor R14 is electrically connected to the control end of the switch tube K2, the positive terminal of the switch tube K2 is electrically connected to the working power supply VCC of the short-circuit protection circuit, the negative terminal of the switch tube K2 is electrically connected to the first end of the resistor R9, and the second end of the resistor R9 is grounded; a resistor R5 is also electrically connected between the positive terminal of the switch tube K2 and the control end of the switch tube K2; The control end of the switch tube K1 is electrically connected to the first end of the resistor R7, the second end of the resistor R7 is electrically connected to the first end of the resistor R9, and the negative terminal of the switch tube K1 is grounded.

3. A short circuit protection circuit for a battery according to claim 2, characterized in that: The short circuit response unit also includes a resistor R8 and a capacitor C5; the negative terminal of the switch tube K2 is electrically connected to the first end of the resistor R8, and the second end of the resistor R8 is electrically connected to the first end of the resistor R9; the positive electrode of the capacitor C5 is electrically connected to the first end of the resistor R9, and the negative electrode of the capacitor C5 is grounded.

4. A short circuit protection circuit for a battery according to claim 2, characterized in that: The loop closing unit includes a capacitor C6, a resistor R10 and a switch tube K3; The first end of the resistor R10 is electrically connected to the first end of the resistor R9 and the positive electrode of the capacitor C6 respectively, the second end of the resistor R10 is electrically connected to the control end of the switch tube K3, the positive terminal of the switch tube K3 is electrically connected to the control end of the power control switch tube, and the negative electrode of C6 and the negative terminal of the switch tube K3 are both grounded; The switch tube K3 is an NMOS tube or an NPN transistor.

5. A short circuit protection circuit for a battery according to claim 1, characterized in that: The short circuit response unit is electrically connected to a short circuit detection circuit; The short-circuit detection circuit includes a current detection chip U2 for sampling the voltage drop across the current-sensing resistor in the battery discharge circuit, and amplifying the sampled voltage drop according to a preset amplification factor and then outputting it; the output end of the current detection chip U2 is electrically connected to a short-circuit identification unit circuit; The short circuit identification unit circuit includes a resistor R3, a resistor R4, a capacitor C4 and a controllable precision voltage-stabilizing source U1; the output end of the current detection chip U2 is electrically connected to the first end of the resistor R4, the second end of R4 is grounded, the first end of the resistor R3 is electrically connected to the positive electrode of the capacitor C4 and the reference end of the controllable precision voltage-stabilizing source U1 respectively, the second end of the resistor R3 is electrically connected to the first end of the resistor R4, the positive electrode of the controllable precision voltage-stabilizing source U1 is electrically connected to the input end of the short circuit response unit, and the negative electrode of the controllable precision voltage-stabilizing source U1 is grounded; When a short circuit occurs in the battery discharge circuit, the voltage output by the current detection chip U2 is greater than or equal to a preset threshold voltage, the controllable precision voltage regulator U1 is turned on, and the input end of the short circuit response unit is connected to a low level signal.

6. A short-circuit protection circuit for a battery according to claim 5, characterized in that: The current detection chip U2 has a built-in differential amplifier and NPN transistor; The positive terminal of the current-sensing resistor is electrically connected to the first end of the resistor R1, and the negative terminal of the current-sensing resistor is electrically connected to the first end of the resistor R2, and the resistor R1 and the resistor R2 are resistors with the same resistance value; the second end of the resistor R1 is electrically connected to the positive input end of the differential amplifier and the positive electrode of the capacitor C1, respectively, and the second end of the resistor R2 is electrically connected to the negative input end of the differential amplifier and the negative electrode of the capacitor C1, respectively; the output end of the differential amplifier is electrically connected to the base of the NPN transistor, the collector of the NPN transistor is electrically connected to the positive input end of the differential amplifier, and the emitter of the NPN transistor is the output end of the current detection chip U2; the output end of the current detection chip U2 is also electrically connected to the positive electrode of the capacitor C3, and the negative electrode of the capacitor C3 is grounded; The voltage output by the current detection chip U2 = (resistance value of R4 / resistance value of R2)*voltage difference between the two input terminals of the differential amplifier.

7. A short-circuit protection circuit for a battery according to claim 1, characterized in that: The unlocking module includes a resistor R13, a capacitor C7, a resistor R11 and a switch tube K5; The first end of the resistor R13 is electrically connected to the unlocking signal output end of the MCU of the battery and the positive electrode of the capacitor C7, and the unlocking signal output end of the MCU is used to pull down the input end of the short-circuit signal locking unit to a low-level signal; the second end of the resistor R13 is electrically connected to the first end of the resistor R11 and the control end of the switch tube K5, the negative electrode of the capacitor C7 and the second end of the resistor R11 are grounded, the positive terminal of the switch tube K5 is electrically connected to the output end of the short-circuit response unit, and the negative terminal of the switch tube K5 is grounded; The switch tube K5 is an NMOS tube or an NPN transistor.

8. A short circuit protection circuit for a battery according to claim 4, characterized in that: The self-locking module also short-circuits the notification unit circuit; The short-circuit notification unit circuit includes a resistor R15, a switch tube K4, a resistor R16 and a resistor R12; the first end of the resistor R15 is electrically connected to the control end of the switch tube K3 and the control end of the switch tube K4, the second end of the resistor R15 and the negative terminal of the switch tube K4 are both grounded, the first end of the resistor R16 is electrically connected to the working power supply VCC, the second end of the resistor R16 is electrically connected to the positive terminal of the switch tube K4 and the first end of the resistor R12, and the second end of the resistor R12 is electrically connected to the short-circuit signal monitoring end of the MCU of the battery; The switch tube K4 is an NMOS tube or an NPN transistor.

9. A short circuit protection circuit for a battery according to claim 1, characterized in that: The short circuit response unit is electrically connected to a short circuit detection circuit; The short-circuit detection circuit includes a current detection chip U2 for sampling the voltage drop across the current-sensing resistor in the battery discharge circuit, and amplifying the sampled voltage drop according to a preset amplification factor and then outputting it; the output end of the current detection chip U2 is electrically connected to a short-circuit identification unit circuit; The short circuit identification unit circuit includes a resistor R3, a resistor R4, a sliding resistor RU and a voltage comparator U1A; wherein the voltage comparator U1A adopts an LM311 voltage comparator; The first pin of the voltage comparator U1A is grounded, the second pin of the voltage comparator U1A is electrically connected to the first end of the resistor R3, the third pin of the voltage comparator U1A is electrically connected to the sliding adjustment end of the sliding rheostat RU, the fourth pin of the voltage comparator U1A is grounded, the seventh pin of the voltage comparator U1A is electrically connected to the input end of the short-circuit response unit, and the eighth pin of the voltage comparator U1A is electrically connected to the working power supply VCC of the short-circuit protection circuit; the second end of the resistor R3 is electrically connected to the output end of the current detection chip U2 and the first end of the resistor R4, respectively, the second end of R4 is grounded, the first end of the sliding rheostat RU is electrically connected to the working power supply VCC, and the second end of the sliding rheostat RU is grounded; When a short circuit occurs in the battery discharge circuit, the voltage output by the current detection chip U2 is greater than or equal to a preset threshold voltage, and the seventh pin of the voltage comparator U1A outputs a low level signal.

10. An electrical device, comprising a battery discharge circuit, wherein a current sensing resistor and a power control switch tube for controlling the on / off of the battery discharge circuit are provided in the battery discharge circuit, characterized in that: Also includes a short circuit protection circuit of a battery as described in any one of claims 1 to 9; The input end of the short-circuit response unit is electrically connected to a short-circuit detection circuit for sampling a voltage drop across a current-sensing resistor; the short-circuit detection circuit is also used to output a low-level signal to the short-circuit response unit when a short circuit occurs in a battery discharge circuit.

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