PTC (Positive Temperature Coefficient) resistor current-limiting pre-discharge circuit and battery

Abstract

The utility model provides a PTC (Positive Temperature Coefficient) resistor current-limiting pre-discharge circuit and a battery, the PTC resistor current-limiting pre-discharge circuit comprises an enable circuit, an input circuit and an output circuit, the enable circuit comprises a first control tube, and a first resistor and a protective resistor which are connected in series, the input circuit comprises a second control tube and a second resistor, the output circuit comprises a protection diode and at least one PTC thermistor, the first end of the PTC thermistor is connected with the second end of the second control tube, the second end of the PTC thermistor is connected with the charging and discharging positive electrode through the positive electrode and the negative electrode of the protection diode in sequence, when the circuit is overloaded, the PTC thermistor responds rapidly, the resistance value is automatically adjusted to rapidly limit the current, and the charging and discharging time is shortened. When the circuit is in a high-temperature state, the resistance value of the PTC thermistor is increased along with the rise of the temperature so as to limit the current, the resistance value is recovered after the overload effect is relieved so as to enable the circuit to work normally, and the circuit can work stably when the circuit is applied to a pre-discharge circuit.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a PTC resistor current limiting pre-discharge circuit and a battery. Background Art

[0002] According to current technology, BMS pre-discharge is a technology used by the battery management system during the discharge process. It is mainly used to reduce the impact of discharge current, reduce the burden on the battery, and improve the performance and safety of the battery. The so-called pre-discharge is the pre-discharge of the battery to the outside.

[0003] At present, the common pre-discharge method is to limit the current through a conventional resistor, such as the Chinese patent publication number CN111817263B. The existing circuit diagram is as follows Figure 1 As shown, in order to reduce the reduction of battery safety performance due to excessive current, a conventional current limiting resistor R_Group is added at both ends of PRE_R_P and PRE_R_G for current limiting. Specifically, the current limiting resistor R_Group is a 2512 chip package resistor. In addition, this circuit is also provided with a thermal sensing switch DT1. When the resistance temperature reaches 90°C, the thermal sensing switch DT1 is triggered to perform a power-off operation to protect the battery from abnormal conditions such as thermal runaway. In the case of a large output capacitance, it is necessary to increase the resistance to ensure the output capacity. In the figure, there are multiple sub-resistors (greater than or equal to 10) in the resistor R_Group.

[0004] Since the resistance value of the resistor is affected by factors such as temperature, voltage and time, the effect of limiting current under different circuit conditions is unstable. When the current is abnormal, the dynamic response speed is slow and cannot quickly adapt to changes in the circuit load. When the resistor temperature does not reach 90°C and is at a high temperature for a long time, the resistor loss is large, which in turn affects the battery life.

[0005] In view of the above problems, there is an urgent need for a resistor current limiting pre-discharge circuit with effective overload protection and fast dynamic response speed. Utility Model Content

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a PTC resistor current limiting pre-discharge circuit and a battery with effective overload protection and fast dynamic response speed.

[0007] The purpose of this disclosure is achieved through the following technical solutions:

[0008] A PTC resistor current limiting pre-discharge circuit comprises an enabling circuit, an input circuit and an output circuit, wherein the enabling circuit is used to control the on-off state of the input circuit, the enabling circuit comprises a first control tube, a first resistor and a protection resistor connected in series, the control end of the first control tube is connected to a signal enabling end through the first resistor, the control end of the first control tube is connected to a second end of the first control tube through the protection resistor, the second end of the first control tube is connected to a digital ground, the input circuit comprises a second control tube and a second resistor, the control end of the second control tube is connected to a positive electrode of a battery through the second resistor, the control end of the second control tube is connected to a first end of the first control tube, the first end of the second control tube is connected to the positive electrode of the battery, the output circuit comprises a protection diode and at least one PTC thermistor, the first end of the PTC thermistor is connected to the second end of the second control tube, the second end of the PTC thermistor is connected to an anode of the protection diode, and the cathode of the protection diode is connected to a positive electrode of charging and discharging.

[0009] In one embodiment, the at least one PTC thermistor is a first thermistor and a second thermistor connected in parallel.

[0010] In one embodiment, the first thermistor and the second thermistor are both of model PTC25R_PPL11250A2C8.

[0011] In one embodiment, the input circuit further includes a third resistor, and the first end of the first control tube is connected to the control end of the second control tube through the third resistor.

[0012] In one embodiment, at least one of the first resistor and the protection resistor is an adjustable resistor, which is used to provide a turn-on voltage of the first control tube.

[0013] In one embodiment, the second resistor is an adjustable resistor.

[0014] In one embodiment, the third resistor is an adjustable resistor.

[0015] In one embodiment, the first control tube is an NPN transistor.

[0016] In one embodiment, the second control transistor is a P-channel MOS transistor.

[0017] A battery comprises the PTC resistor current limiting pre-discharge circuit described in any one of the above embodiments.

[0018] Compared with the prior art, the present invention has at least the following advantages:

[0019] When the signal enable terminal of the enable circuit triggers a high-level enable signal, due to the voltage drop of the protection resistor, the current is conducted from the positive electrode of the battery to the first control tube, and the current is grounded. Due to the voltage drop of the second resistor, the circuit conducts the second control tube, and further connects the input circuit and the output circuit. When the circuit is overloaded, the PTC thermistor responds quickly and automatically adjusts the resistance value to quickly limit the current and protect the components in the circuit, thereby achieving overload protection and rapid response effects. When the circuit is in a high temperature state, the resistance value of the PTC thermistor increases with the increase of temperature to limit the current. After the overload effect is released, the resistance value is restored to its normal value to allow the circuit to work normally. In this way, it can work stably when applied to the pre-discharge circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A circuit diagram of the prior art;

[0022] Figure 2 The present invention is a circuit diagram of a PTC resistor current limiting pre-discharge circuit according to an embodiment. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0026] A PTC resistor current limiting pre-discharge circuit comprises an enabling circuit, an input circuit and an output circuit, wherein the enabling circuit is used to control the on-off state of the input circuit, the enabling circuit comprises a first control tube, a first resistor and a protection resistor connected in series, the control end of the first control tube is connected to a signal enabling end through the first resistor, the control end of the first control tube is connected to a second end of the first control tube through the protection resistor, the second end of the first control tube is connected to a digital ground, the input circuit comprises a second control tube and a second resistor, the control end of the second control tube is connected to a positive electrode of a battery through the second resistor, the first end of the second control tube is connected to the positive electrode of the battery, the control end of the second control tube is connected to the first end of the first control tube, the output circuit comprises a protection diode and at least one PTC thermistor, the first end of the PTC thermistor is connected to the second end of the second control tube, the second end of the PTC thermistor is connected to the anode of the protection diode, and the cathode of the protection diode is connected to a positive electrode of charging and discharging.

[0027] When the signal enable terminal of the enable circuit triggers a high-level enable signal, due to the voltage drop of the protection resistor, the current is conducted from the positive electrode of the battery to the first control tube, and the current is grounded. Due to the voltage drop of the second resistor, the circuit conducts the second control tube, and further connects the input circuit and the output circuit. When the circuit is overloaded, the PTC thermistor responds quickly and automatically adjusts the resistance value to quickly limit the current and protect the components in the circuit, thereby achieving overload protection and rapid response effects. When the circuit is in a high temperature state, the resistance value of the PTC thermistor increases with the increase of temperature to limit the current. After the overload effect is released, the resistance value is restored to its normal value to allow the circuit to work normally. In this way, it can work stably when applied to the pre-discharge circuit.

[0028] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0029] like Figure 2As shown, a PTC resistor current limiting pre-discharge circuit 10 of an embodiment includes an enabling circuit 100, an input circuit 200 and an output circuit 300. The enabling circuit 100 is used to control the on-off state of the input circuit 200. The enabling circuit 100 includes a first control tube Q12, a first resistor R83 and a protection resistor R84 connected in series. The control end of the first control tube Q12 is connected to the signal enable end ON_OFF_P_DIS through the first resistor R83, the control end of the first control tube Q12 is connected to the second end of the first control tube Q12 through the protection resistor R84, and the second end of the first control tube Q12 is connected to the digital ground GNDD. The input circuit 200 includes a second control tube Q10 and a second resistor R75. The second control tube Q10 is connected to the digital ground GNDD. The control end of the control tube Q10 is connected to the positive electrode B++ of the battery through the second resistor R75, the control end of the second control tube Q10 is connected to the first end of the first control tube Q12, the first end of the second control tube Q10 is connected to the positive electrode B++ of the battery, the output circuit 300 includes a protection diode D15 and at least one PTC thermistor Rp, the first end of the PTC thermistor Rp is connected to the second end of the second control tube Q10, specifically, the PTC thermistor Rp is connected in series with the second control tube Q10, the second end of the PTC thermistor Rp is connected to the anode of the protection diode D15, the cathode of the protection diode D15 is connected to the charging and discharging positive electrode P+ / C+, specifically, the PTC thermistor Rp is connected in series with the protection diode D15.

[0030] Furthermore, voltage test terminals T76 and T77 are respectively provided at both ends of the PTC thermistor Rp. The test terminals T76 and T77 are used for testing and verification when the circuit is working, and for measuring the voltage of the PTC thermistor Rp. The two collection terminals PRE_R_P and PRE_R_G of the PTC thermistor Rp are connected to the voltage collection part of the microcontroller unit (MCU) for collecting voltage data of the PTC thermistor Rp. Some technologies for voltage collection of the PTC thermistor Rp have been disclosed and will not be elaborated here.

[0031] The specific implementation of the above-mentioned PTC resistor current limiting pre-discharge circuit 10 is as follows:

[0032] When there is no level signal or a low level signal input to the signal enable terminal ON_OFF_P_DIS, the first control tube Q12 and the second control tube Q10 are turned off, and the circuit is in a standby state. When the circuit receives a discharge command, the signal enable terminal ON_OFF_P_DIS triggers a high level enable signal for 1.5 seconds, and the current passes through the first resistor R83 and the protection resistor R84 in turn. The protection resistor R84 generates a voltage drop, so that a positive voltage is applied between the second end of the first control tube Q12 and the control end, and a negative voltage is applied between the first end of the first control tube Q12 and the control end, thereby The first control tube Q12 is turned on. At this time, the current flows from the positive electrode of the battery B++ through the second resistor R75 and the first control tube Q12 connected to the digital ground GNDD. The second resistor R75 generates a voltage drop, and the second control tube Q10 is turned on to start the pre-discharge circuit. Subsequently, the current is output from the second control tube Q10 through the PTC thermistor Rp and the protection diode D15 to the positive electrode of the power supply P+. The PTC thermistor Rp causes a change in resistance value as its own temperature changes, which plays a role in limiting the current. The protection diode D1 is used to prevent current backflow and avoid component damage caused by current backflow.

[0033] In this embodiment, the first control tube Q12 is an NPN transistor, the control end of the first controller Q12 is the base b, the first end of the first controller Q12 is the collector c, and the second end of the first controller Q12 is the emitter e; the second control tube Q10 is a PMOS tube, the control end of the second control tube Q10 is the gate G, the first end of the second control tube Q10 is the source S, and the second end of the second control tube Q10 is the drain D. The following embodiments can be explained.

[0034] Furthermore, the model of the first control tube Q12 is FMBT5551, the model of the second control tube Q10 is NCE15P25JK, and the model of the protection diode is 1N4007.

[0035] In one embodiment, at least one PTC thermistor Rp is a first thermistor RT_SS1 and a second thermistor RT_SS2 connected in parallel. It can be understood that the first thermistor RT_SS1 and the second thermistor RT_SS2 connected in parallel constitute the PTC thermistor Rp, which can limit the current. When the current is overloaded or the voltage is unstable, the battery temperature rises, and the first thermistor RT_SS1 and the second thermistor RT_SS2 respond quickly to adjust the resistance value. Specifically, when the battery temperature rises, the resistance values ​​of the first thermistor RT_SS1 and the second thermistor RT_SS2 increase with the temperature, thereby limiting the current and protecting the components in the circuit. In other embodiments, in the PTC thermistor Rp, the number of thermistors can be 1, 3, or more than 3, as long as it does not affect the protection effect of the components in the circuit.

[0036] In one embodiment, the models of the first thermistor RT_SS1 and the second thermistor RT_SS2 are both PTC 25R_PPL11250A2C8.

[0037] In one embodiment, the input circuit 200 further includes a third resistor R80 , and the first end of the first control transistor Q12 is connected to the control end of the second control transistor Q10 through the third resistor R80 .

[0038] Furthermore, the third resistor R80 is connected in series with the first control tube Q12, and the third resistor R80 is used to further protect the first control tube Q12, further preventing the current from being too large so that the voltage at the first end of the first control tube Q12 is too large, resulting in the breakdown of the first control tube Q12. Furthermore, the second resistor R75, the third resistor R80 and the first control tube Q12 are connected in series to divide the voltage, further reducing the voltage at the first end of the first control tube Q12, and ensuring the normal operation of the first control tube Q12.

[0039] In one embodiment, at least one of the first resistor R83 and the protection resistor R84 is an adjustable resistor, which is used to change the on-voltage of the first control tube Q12. Further, the first resistor R83 and the protection resistor R84 are connected in series to divide the voltage, so as to provide the on-voltage of the first control tube Q12, and adjust the resistance value of the first resistor R83 or the protection resistor R84 to adjust the on-voltage condition of the first control tube Q12.

[0040] Furthermore, the resistance value of the first resistor R83 is 300 kΩ, and the allowable error ratio is ±1%; the resistance value of the protection resistor R84 is 510 kΩ, and the allowable error ratio is ±1%.

[0041] In one embodiment, the second resistor R75 is an adjustable resistor. Further, by adjusting the resistance value of the second resistor R75, the conduction condition of the second control tube Q10 is adjusted, so that when the first control tube Q12 is turned on, the first terminal voltage of the second control tube Q10 is greater than the control terminal voltage and then turned on. Furthermore, the resistance value of the second resistor R75 is 300kΩ, and the allowable error ratio is ±1%.

[0042] In one embodiment, the third resistor R80 is an adjustable resistor. Further, the resistance value of the third resistor R80 is 300 kΩ, and the allowable error ratio is ±1%.

[0043] In one embodiment, the first control tube Q12 is an NPN transistor, which will not be described in detail here.

[0044] In one embodiment, the second control transistor Q10 is a P-channel MOS transistor, which will not be described in detail here.

[0045] The present disclosure further provides a battery, comprising the PTC resistor current limiting pre-discharge circuit 10 of any of the above embodiments.

[0046] Compared with the prior art, the present invention has at least the following advantages:

[0047] When the signal enable terminal ON_OFF_P_DIS of the enable circuit 100 triggers a high-level enable signal, the first resistor R83 and the protection resistor R84 are connected in series to divide the voltage, and the protection resistor R84 generates a voltage drop. The current flows from the positive electrode B++ of the battery through the second resistor R75 to turn on the first control tube Q12 to ground. Since the second resistor R75 generates a voltage drop, the circuit turns on the second control tube Q10, and further connects the input circuit 200 and the output circuit 300. When the circuit is overloaded, the PTC thermistor Rp responds quickly and automatically adjusts the resistance value to quickly limit the current and protect the components in the circuit, thereby achieving overload protection and rapid response effects. When the circuit is in a high temperature state, the resistance value of the PTC thermistor Rp increases with the increase of temperature to limit the current. After the overload effect is released, the resistance value is restored to its normal value to allow the circuit to work normally. In this way, it can work stably when applied to the pre-discharge circuit.

[0048] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A PTC resistor current limiting pre-discharge circuit, comprising an enabling circuit and an input circuit, wherein the enabling circuit is used to control the on / off state of the input circuit, wherein the enabling circuit comprises a first control tube, a first resistor and a protection resistor connected in series, wherein the control end of the first control tube is connected to the signal enabling end through the first resistor, the control end of the first control tube is connected to the second end of the first control tube through the protection resistor, the second end of the first control tube is connected to a digital ground, the input circuit comprises a second control tube and a second resistor, the control end of the second control tube is connected to the positive electrode of a battery through the second resistor, the control end of the second control tube is connected to the first end of the first control tube, and the first end of the second control tube is connected to the positive electrode of the battery, characterized in that: The PTC resistor current limiting pre-discharge circuit also includes an output circuit, which includes a protection diode and at least one PTC thermistor, wherein the first end of the PTC thermistor is connected to the second end of the second control tube, the second end of the PTC thermistor is connected to the anode of the protection diode, and the cathode of the protection diode is connected to the charging and discharging positive electrode.

2. The PTC resistor current limiting pre-discharge circuit according to claim 1, characterized in that: The at least one PTC thermistor is a first thermistor and a second thermistor connected in parallel.

3. The PTC resistor current limiting pre-discharge circuit according to claim 2, characterized in that: Models of the first thermistor and the second thermistor are both PTC 25R_PPL11250A2C8.

4. The PTC resistor current limiting pre-discharge circuit according to claim 1, characterized in that: The input circuit further includes a third resistor, and the first end of the first control tube is connected to the control end of the second control tube through the third resistor.

5. The PTC resistor current limiting pre-discharge circuit according to claim 1, characterized in that: At least one of the first resistor and the protection resistor is an adjustable resistor, which is used to provide a turn-on voltage of the first control tube.

6. The PTC resistor current limiting pre-discharge circuit according to claim 1, characterized in that: The second resistor is an adjustable resistor.

7. The PTC resistor current limiting pre-discharge circuit according to claim 4, characterized in that: The third resistor is an adjustable resistor.

8. The PTC resistor current limiting pre-discharge circuit according to claim 1, characterized in that: The first control tube is an NPN type transistor.

9. The PTC resistor current limiting pre-discharge circuit according to claim 1, characterized in that: The second control tube is a P-channel MOS tube.

10. A battery, characterized in that: It comprises the PTC resistor current limiting pre-discharge circuit as described in any one of claims 1 to 9.

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