Over-current protection circuit and system based on short-circuit protection

Abstract

The utility model provides an overcurrent protection circuit and system based on short-circuit protection. The emitter of a first triode is connected with a power supply; the first end of the first resistor is connected with the emitter of the first triode, and the second end is connected with the base of the first triode; the first end of the second resistor is connected with the emitter of the first triode; the second end of the second resistor is connected with the collector of the first triode; the input end of the voltage stabilizer is connected with the collector of the first triode, and the output end of the voltage stabilizer is connected with the second end of the first resistor and serves as the output end of the overcurrent protection circuit. Compared with a traditional software protection mechanism, a hardware short-circuit overcurrent protection circuit is established, operation of a certain time is not needed, response is fast, overcurrent abnormity is effectively limited in time, and the method is quite suitable for occasions with high sensitivity requirements.

Description

Technical Field

[0001] The utility model relates to the technical field of electric vehicles and circuit protection, and in particular to an overcurrent protection circuit and system based on short-circuit protection. Background Art

[0002] New energy vehicles will play a vital role in promoting the development of new energy. There are many reasons for the spontaneous combustion of new energy vehicles. In addition to the weather, the battery itself and the battery management system BMS are very important. One of the reasons for BMS damage or spontaneous combustion is the high current caused by a short circuit.

[0003] The current acquisition of the battery management system (BMS) generally converts the current signal into a voltage signal through a shunt or a Hall sensor, and then processes the voltage signal. It is usually processed using a front-end analog integrated IC or a dedicated current acquisition chip, and then the amplified signal is transmitted to the microcontroller unit MCU. The MCU compares the preset current parameters with the current parameters after acquisition and amplification, and makes corresponding control output protection signals to cut off the main circuit. This protection mechanism belongs to the software protection type. The operation requires a certain amount of time, the response is not fast enough, and the over-current anomaly cannot be effectively limited in a timely manner. It is not suitable for occasions with high sensitivity requirements. Utility Model Content

[0004] Based on the above records, the utility model provides an overcurrent protection circuit and system based on short-circuit protection, aiming to solve the technical problem in the prior art that the response to overcurrent abnormalities is not fast enough.

[0005] An overcurrent protection circuit based on short circuit protection, comprising:

[0006] A first triode, wherein the emitter of the first triode is connected to a power supply;

[0007] A first resistor, wherein a first end of the first resistor is connected to the emitter of the first transistor, and a second end of the first resistor is connected to the base of the first transistor;

[0008] a second resistor, wherein a first end of the second resistor is connected to the emitter of the first transistor, and a second end of the second resistor is connected to the collector of the first transistor;

[0009] A voltage stabilizer, wherein the input end of the voltage stabilizer is connected to the collector of the first triode, and the output end of the voltage stabilizer is connected to the second end of the first resistor and serves as the output end of the overcurrent protection circuit.

[0010] Furthermore, the output terminal of the voltage regulator and the second terminal of the first resistor are further connected:

[0011] a second triode, wherein the emitter of the second triode is connected to the second end of the first resistor, and the base of the second triode is connected to the collector of the first triode;

[0012] The output end of the voltage stabilizer is connected to the collector of the second transistor and serves as the output end of the overcurrent protection circuit.

[0013] Furthermore, the first transistor and the second transistor are both of PNP type.

[0014] Furthermore, the voltage regulator is a linear voltage regulator.

[0015] Furthermore, it also includes:

[0016] A first capacitor, wherein a first end of the first capacitor is connected to the input end of the voltage regulator, and a second end of the first capacitor is grounded.

[0017] Furthermore, it also includes:

[0018] A second capacitor, wherein a first end of the second capacitor is connected to the output end of the voltage regulator, and a second end of the second capacitor is grounded.

[0019] Furthermore, the voltage regulator further includes a ground terminal.

[0020] An overcurrent protection system based on short circuit protection comprises a battery management system and the above-mentioned overcurrent protection circuit based on short circuit protection, wherein the output end of the overcurrent protection circuit is connected to the battery management system.

[0021] Furthermore, the voltage of the power supply is 15 volts, and the resistance of the second resistor is 5 ohms.

[0022] Furthermore, the resistance of the first resistor is 0.1 ohm.

[0023] The beneficial technical effect of the utility model is: by establishing a hardware short-circuit overcurrent protection circuit, when the circuit is short-circuited, the large current is controlled in an ideal current state, and the protection will not be lost due to excessive current. Compared with the traditional software protection mechanism, it does not require a certain amount of time for calculation, has a fast response, and can effectively limit overcurrent anomalies in a timely manner. It is very suitable for occasions with high sensitivity requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The utility model is a circuit structure of an overcurrent protection circuit based on short-circuit protection;

[0025] Figure 2 This is a short-circuit simulation circuit for a specific application of an overcurrent protection circuit based on short-circuit protection of the utility model;

[0026] Figure 3 The utility model discloses a simulation circuit when there is no short circuit in a specific application of an overcurrent protection circuit based on short circuit protection. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0029] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0030] See also Figure 1 The utility model provides an overcurrent protection circuit based on short circuit protection, comprising:

[0031] A first transistor (Q1), wherein an emitter of the first transistor (Q1) is connected to a power supply (VCC);

[0032] A first resistor (R1), wherein a first end of the first resistor (R1) is connected to an emitter of a first transistor (Q1), and a second end of the first resistor (R1) is connected to a base of the first transistor (Q1);

[0033] a second resistor (R2), wherein a first end of the second resistor (R2) is connected to the emitter of the first transistor (Q1), and a second end of the second resistor (R2) is connected to the collector of the first transistor (Q1);

[0034] A voltage stabilizer (U1) is provided, wherein the input end of the voltage stabilizer (U1) is connected to the collector of the first transistor (Q1), and the output end of the voltage stabilizer (U1) is connected to the second end of the first resistor (R1) and serves as the output end of the overcurrent protection circuit.

[0035] The output terminal of the overcurrent protection circuit of the utility model is connected to the target system to be protected, for example, the battery management system BMS, and provides an overcurrent protection circuit in case of short circuit by means of pure hardware circuit. When the circuit is not short-circuited, the normal output voltage is output. When short-circuited, the current is limited, and the output voltage is reduced at this time, protecting the target system from overcurrent and protecting the BMS.

[0036] The second resistor (R2) provides an excitation current to the voltage regulator (U1) to enable it to operate normally.

[0037] The first transistor (Q1) generates a voltage drop to provide a voltage to the first resistor (R1). The maximum current allowed to pass through the voltage regulator (U1) is provided by calculating the resistance value of the first resistor (R1). When short-circuited, the current is limited to the maximum current.

[0038] The voltage regulator plays a voltage stabilizing role in the circuit, providing high-quality, low-ripple stable output voltage.

[0039] By establishing a hardware short-circuit overcurrent protection circuit, when the circuit is short-circuited, the large current will be controlled at an ideal current state, and the protection will not be lost due to excessive current. Compared with the traditional software protection mechanism, it does not require a certain amount of time for calculation, has a fast response, and can effectively limit overcurrent anomalies in a timely manner. It is very suitable for occasions with high sensitivity requirements.

[0040] Furthermore, the output terminal of the voltage regulator (U1) and the second terminal of the first resistor (R1) are further connected:

[0041] a second triode (Q2), wherein the emitter of the second triode (Q2) is connected to the second end of the first resistor (R1), and the base of the second triode (Q2) is connected to the collector of the first triode (Q1);

[0042] The output end of the voltage regulator (U1) is connected to the collector of the second transistor (Q2) and serves as the output end of the overcurrent protection circuit.

[0043] The second transistor (Q2) plays a role in expanding the current and thus increasing the load capacity of the circuit.

[0044] Furthermore, the first transistor (Q1) and the second transistor (Q2) are both of PNP type.

[0045] Furthermore, the voltage regulator (U1) is a linear voltage regulator.

[0046] For example, the linear regulator MC78L12ACP.

[0047] Furthermore, it also includes:

[0048] A first capacitor (C1), wherein a first end of the first capacitor (C1) is connected to an input end of the voltage regulator (U1), and a second end of the first capacitor (C1) is grounded.

[0049] Furthermore, it also includes:

[0050] A second capacitor (C2), wherein a first end of the second capacitor (C2) is connected to the output end of the voltage regulator (U1), and a second end of the second capacitor (C2) is grounded.

[0051] Furthermore, the voltage regulator (U1) also includes a ground terminal.

[0052] The voltage stabilizer is a three-terminal voltage stabilizer, one end is input, one end is output, and one end is grounded.

[0053] The utility model also provides an overcurrent protection system based on short-circuit protection, comprising a battery management system and an overcurrent protection circuit based on short-circuit protection as claimed in claims 1-7, wherein the output end of the overcurrent protection circuit is connected to the battery management system.

[0054] The output end of the overcurrent protection circuit of the utility model can be connected to a battery management system BMS, for example, and a short-circuit overcurrent protection circuit is provided to the battery management system (BMS) in a pure hardware circuit manner. When the circuit is not short-circuited, the normal output voltage is output, and when short-circuited, the current is limited, and the output voltage is reduced at this time, protecting the BMS from overcurrent and protecting the BMS.

[0055] Furthermore, the voltage of the power supply (VCC) is 15 volts, and the resistance of the second resistor (R2) is 5 ohms.

[0056] Furthermore, the resistance of the first resistor (R1) is 0.1 ohm.

[0057] Furthermore, the capacity of the first capacitor (C1) is 0.33 microfarads.

[0058] Furthermore, the capacity of the second capacitor (C2) may be 0.1 microfarad.

[0059] In actual applications, the output current of the three-terminal regulator is required to exceed 1A. In this case, a second transistor (Q2) is added in front of the three-terminal regulator to achieve the dual functions of expanding the output current and setting the protection current size. When the current in the circuit increases, the voltage drop across the first resistor (R1) will also increase. When the voltage V R1 >V BE (V BE is the conduction voltage of the first transistor (Q1), the first transistor (Q1) is turned on to limit the emitter and collector currents of the second transistor (Q2) to continue to increase, thereby protecting Q2 from being burned by the large current. When the load or the voltage stabilizing circuit itself is accidentally short-circuited due to design or device reasons, the circuit of the utility model adopts a first resistor with a resistance of 0.1 ohm, a second resistor with a resistance of 5 ohm, and a power supply voltage VCC of 15 volts, the maximum current is limited to I R1 =(V BE ) / R1≈0.7V / 0.1=7A, so the maximum current of the circuit is limited to about 7A. Figure 2-3 As shown, use ammeter U1 to measure the output current, the circuit equivalent resistance is RL, and voltmeter U2 to measure the output voltage. When the power supply voltage VCC is 15 volts, when the circuit is not short-circuited, the normal output voltage is about 12V. When short-circuited, the current is limited to about 7A. At this time, the output voltage is reduced to protect the BMS from overcurrent.

[0060] The above are only preferred embodiments of the present invention, and do not limit the implementation mode and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An overcurrent protection circuit based on short circuit protection, characterized in that: include: A first triode, wherein the emitter of the first triode is connected to a power supply; a first resistor, wherein a first end of the first resistor is connected to the emitter of the first transistor, and a second end of the first resistor is connected to the base of the first transistor; a second resistor, wherein a first end of the second resistor is connected to the emitter of the first transistor, and a second end of the second resistor is connected to the collector of the first transistor; A voltage stabilizer, wherein the input end of the voltage stabilizer is connected to the collector of the first transistor, and the output end of the voltage stabilizer is connected to the second end of the first resistor and serves as the output end of the overcurrent protection circuit.

2. An overcurrent protection circuit based on short circuit protection as claimed in claim 1, characterized in that: The output end of the voltage regulator and the second end of the first resistor are further connected: a second triode, wherein the emitter of the second triode is connected to the second end of the first resistor, and the base of the second triode is connected to the collector of the first triode; The output end of the voltage stabilizer is connected to the collector of the second transistor and serves as the output end of the overcurrent protection circuit.

3. An overcurrent protection circuit based on short circuit protection as claimed in claim 2, characterized in that: The first transistor and the second transistor are both of PNP type.

4. An overcurrent protection circuit based on short circuit protection as claimed in claim 1, characterized in that: The voltage regulator is a linear voltage regulator.

5. An overcurrent protection circuit based on short circuit protection as claimed in claim 1, characterized in that: Also includes: A first capacitor, wherein a first end of the first capacitor is connected to the input end of the voltage regulator, and a second end of the first capacitor is grounded.

6. An overcurrent protection circuit based on short circuit protection as claimed in claim 1, characterized in that: Also includes: A second capacitor, wherein a first end of the second capacitor is connected to the output end of the voltage regulator, and a second end of the second capacitor is grounded.

7. An overcurrent protection circuit based on short circuit protection as claimed in claim 1, characterized in that: The voltage regulator also includes a ground terminal.

8. An overcurrent protection system based on short circuit protection, characterized in that: It comprises a battery management system and an overcurrent protection circuit based on short-circuit protection as described in claims 1-7, wherein the output end of the overcurrent protection circuit is connected to the battery management system.

9. An overcurrent protection system based on short circuit protection as claimed in claim 8, characterized in that: The voltage of the power supply is 15 volts, and the resistance of the second resistor is 5 ohms.

10. An overcurrent protection system based on short circuit protection as claimed in claim 9, characterized in that: The resistance of the first resistor is 0.1 ohm.

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