Nickel-metal hydride battery charging overvoltage protection circuit

Abstract

The utility model is suitable for the technical field of nickel-metal hydride batteries, and relates to a nickel-metal hydride battery charging overvoltage protection circuit, which comprises a constant current charging circuit and an overvoltage protection circuit, the constant current charging circuit is electrically connected with the overvoltage protection circuit; the charging circuit is used for charging the nickel-metal hydride battery by using the system power supply; and the overvoltage protection circuit is used for preventing the charging voltage of the nickel-metal hydride battery from being higher than a rated value. The over-voltage protection circuit is simple in structure, convenient in process and low in cost, and solves the problems that an existing circuit is not accurate enough in voltage stabilization and poor in over-voltage protection effect.

Description

Technical Field

[0001] The utility model belongs to the technical field of nickel-hydrogen batteries, and in particular relates to a nickel-hydrogen battery charging overvoltage protection circuit. Background Art

[0002] As a backup power source, nickel-metal hydride batteries have been widely used in low-voltage power collection terminals. After the main power is lost, the terminal is required to continue to operate for a period of time under the power supply of the backup power supply, save important data and report abnormal events during this period. In addition, the relevant technical specifications of the industry have strict requirements on the working time of nickel-metal hydride batteries after the main power is lost. However, the terminal usually operates in an outdoor environment, which is difficult to maintain in real time, so the backup power supply is required to have good performance and life. Long-term overvoltage charging of nickel-metal hydride batteries will accelerate the attenuation of battery capacity and have an adverse effect on the performance and life of nickel-metal hydride batteries. There are restrictive measures for overvoltage charging of nickel-metal hydride batteries. At present, the design of parallel voltage regulator diodes is mostly used to prevent nickel-metal hydride batteries from overvoltage charging. However, the working voltage range of the voltage regulator diode is large, and it is difficult to maintain a relatively accurate voltage regulation value for batch products, resulting in poor overvoltage charging protection of existing products.

[0003] The patent with publication number CN203233154U provides a nickel-hydrogen battery overcharge protection circuit, including a main circuit and an external control circuit, wherein the main circuit includes a nickel-hydrogen battery, a voltage stabilizing diode TL431 and a lithium battery protection chip S8261, wherein the positive electrode of the nickel-hydrogen battery is connected to pin 5 of the lithium battery protection chip S8261 through the voltage stabilizing diode TL431 and the first resistor R1 in sequence; the positive electrode of the nickel-hydrogen battery is connected to the anode A of the voltage stabilizing diode TL431, and the cathode K of the voltage stabilizing diode TL431 is connected to the first resistor R1; the negative electrode of the nickel-hydrogen battery is directly connected to pin 6 of the lithium battery protection chip S8261; the pin 2 of the lithium battery protection chip S8261 is connected to the negative electrode of the nickel-hydrogen battery through the second resistor R2; the pin 3 of the lithium battery protection chip S8261 controls the on and off of the charger of the nickel-hydrogen battery through the external control circuit. Although this patent solves the problem of low precision of the prior art, its circuit structure is relatively complex and the cost is high, and there are still disadvantages.

[0004] Therefore, how to provide a circuit with accurate voltage stabilization value and good overvoltage protection effect is a problem that needs to be solved urgently by people in this technical field. Utility Model Content

[0005] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a nickel-hydrogen battery charging overvoltage protection circuit to solve the problems of low voltage stabilization value accuracy and poor overvoltage charging protection effect of the prior art total overvoltage protection circuit.

[0006] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0007] The utility model provides a nickel-hydrogen battery charging overvoltage protection circuit, comprising:

[0008] An electrically connected constant current charging circuit and an overvoltage protection circuit;

[0009] The constant current charging circuit includes a power chip D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, an NPN transistor V1, an NMOS transistor V2 and a diode V3. One end of the resistor R1 and the resistor R2 are connected to the fast charge control state interface CHARGE, the other end of the resistor R2 is grounded, the other end of the resistor R1 is connected to the base of the NPN transistor V1, the collector of the NPN transistor V1 is connected to one end of the resistor R3 and the gate of the NMOS transistor V2, the emitter of the NPN transistor V1 is grounded, the drain of the NMOS transistor V2 is connected to one end of the resistor R4, the source of the NMOS transistor V2 and one end of the resistor R5 are connected to the first pin of the power chip D1, the cathode of the diode V3 is connected to the other end of the resistor R3 and the third pin of the voltage chip D1, and the anode of the diode V3 is connected to the main power supply V13P0;

[0010] The overvoltage protection circuit includes a voltage reference chip D2, a nickel-hydrogen battery BATTERY1, a resistor R6, a resistor R7 and a resistor R8. The other end of the resistor R4 is connected to the nickel-hydrogen battery BATTERY1, one end of the resistor R6 and one end of the resistor R8 respectively, and the other end of the nickel-hydrogen battery BATTERY1 is grounded. The other end of the resistor R5 is connected to the positive electrode of the nickel-hydrogen battery BATTERY1, one end of the resistor R6 and one end of the resistor R8 respectively. The other end of the resistor R6 is connected to the resistor R7 and the first pin of the voltage reference chip D2 respectively. One end of the resistor R8 is also connected to the second pin of the power chip D1. The other end of the resistor R8 is connected to the second pin of the voltage reference chip D2. The other end of the resistor R7 and the third pin of the voltage reference chip D2 are both grounded.

[0011] Furthermore, it also includes a capacitor C1, one end of which is connected to the cathode of the diode V3, one end of the resistor R3, and the third pin of the power chip D1 respectively.

[0012] Furthermore, the model of the NPN transistor V1 is LMBT4401LT1G.

[0013] Furthermore, the model of the NMOS tube V2 is IRLML6401.

[0014] Furthermore, the model of the diode V3 is 1N1D4148.

[0015] Furthermore, the signal of the voltage reference chip D2 is TLVH431IDBZR.

[0016] Furthermore, the resistance value of the resistor R1 is 3KΩ, the resistance value of the resistor R2 is 10KΩ, the resistance value of the resistor R3 is 100KΩ, the resistance value of the resistor R4 is 100Ω, the resistance value of the resistor R5 is 1KΩ, the resistance value of the resistor R6 is 6.2MΩ, the resistance value of the resistor R7 is 1.6MΩ, and the resistance value of the resistor R8 is 100Ω.

[0017] Furthermore, the capacitance of the capacitor C1 is 0.1 uF.

[0018] Compared with the prior art, the nickel-hydrogen battery charging overvoltage protection circuit provided by the utility model has at least the following beneficial effects:

[0019] At present, the design of parallel voltage stabilizing diodes is mostly used to prevent nickel-hydrogen batteries from overvoltage charging. However, the working voltage range of the voltage stabilizing diode is large, and it is difficult to maintain a relatively accurate voltage stabilizing value for batch products, resulting in poor overvoltage charging protection effect of existing products. The utility model has a simple structure, a convenient process, and a low cost. The designed constant current charging circuit is used to charge the nickel-hydrogen battery with the system power supply, and the designed overvoltage protection circuit is used to prevent the charging voltage of the nickel-hydrogen battery from being higher than the rated value, which solves the problem that the existing overvoltage protection circuit is not accurate enough in voltage stabilization and the overvoltage protection effect is poor. In addition, the utility model can more flexibly adjust the battery voltage limit, and has higher stability and faster response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the scheme of the utility model, a brief introduction is given below to the figures required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A circuit diagram of a nickel-hydrogen battery charging overvoltage protection circuit provided by an embodiment of the utility model;

[0022] Figure 2 A structural block diagram of a nickel-hydrogen battery charging overvoltage protection circuit provided by an embodiment of the utility model;

[0023] Figure 3 The present invention provides a working flow chart of a nickel-hydrogen battery charging overvoltage protection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as commonly understood by technicians in the technical field of the present invention; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the directions or positions indicated by terms such as "length", "width", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", and "outside" are based on the directions or positions shown in the drawings, which are only for the convenience of description and cannot be understood as limitations on the present technical solution.

[0025] The terms "including" and "having" and any variations thereof in the specification and claims of the utility model and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the utility model or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In the specification and claims of the utility model and the above-mentioned drawings, when an element is referred to as "fixed to" or "mounted on" or "disposed on" or "connected to" another element, it may be directly or indirectly located on the other element. For example, when an element is referred to as "connected to" another element, it may be directly or indirectly connected to the other element.

[0026] In addition, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] The utility model provides a nickel-hydrogen battery charging overvoltage protection circuit, which is used to prevent the nickel-hydrogen battery from overvoltage during charging. The nickel-hydrogen battery charging overvoltage protection circuit includes:

[0028] A constant current charging circuit and an overvoltage protection circuit; the constant current charging circuit and the overvoltage protection circuit are electrically connected; the charging circuit is used to charge the nickel-hydrogen battery with the system power supply; the overvoltage protection circuit is used to prevent the charging voltage of the nickel-hydrogen battery from being higher than the rated value.

[0029] The utility model has the advantages of simple structure, convenient process and low cost, and solves the problems of inaccurate voltage stabilization and poor overvoltage protection effect of the existing circuit.

[0030] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiments of the utility model will be clearly and completely described below in conjunction with the accompanying drawings.

[0031] The utility model provides a nickel-hydrogen battery charging overvoltage protection circuit, which is used to prevent the nickel-hydrogen battery from overvoltage charging. Figures 1 to 3 In this embodiment, the nickel-hydrogen battery charging overvoltage protection circuit includes:

[0032] A constant current charging circuit and an overvoltage protection circuit electrically connected, the constant current charging circuit is used to charge the nickel-hydrogen battery with the system power supply, and the overvoltage protection circuit is used to prevent the charging voltage of the nickel-hydrogen battery from being higher than the rated value;

[0033] The constant current charging circuit includes a power chip D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, an NPN transistor V1, an NMOS tube V2 and a diode V3, wherein the constant current charging circuit includes a fast charging circuit and a slow charging circuit, one end of the resistor R1 and the resistor R2 are both connected to the fast charging control state interface CHARGE, the other end of the resistor R2 is grounded, the other end of the resistor R1 is connected to the base of the NPN transistor V1, the collector of the NPN transistor V1 is respectively connected to one end of the resistor R3 and the gate of the NMOS tube V2, the emitter of the NPN transistor V1 is grounded, the drain of the NMOS tube V2 is connected to one end of the resistor R4, the source of the NMOS tube V2 and one end of the resistor R5 are both connected to the first pin of the power chip D1, the cathode of the diode V3 is respectively connected to the other end of the resistor R3 and the third pin of the voltage chip D1, and the anode of the diode V3 is connected to the main power supply V13P0;

[0034] The overvoltage protection circuit includes a voltage reference chip D2, a nickel-hydrogen battery BATTERY1, a resistor R6, a resistor R7 and a resistor R8. The other end of the resistor R4 is connected to the nickel-hydrogen battery BATTERY1, one end of the resistor R6 and one end of the resistor R8 respectively. The other end of the nickel-hydrogen battery BATTERY1 is grounded. The other end of the resistor R5 is connected to the positive electrode of the nickel-hydrogen battery BATTERY1, one end of the resistor R6 and one end of the resistor R8 respectively. The other end of the resistor R6 is connected to the resistor R7 and the first pin of the voltage reference chip D2 respectively. One end of the resistor R8 is also connected to the second pin of the power chip D1. The other end of the resistor R8 is connected to the second pin of the voltage reference chip D2. The other end of the resistor R7 and the third pin of the voltage reference chip D2 are both grounded.

[0035] Furthermore, in this embodiment, the capacitor C1, one end of the capacitor C1 is connected to the cathode of the diode V3, one end of the resistor R3, and the third pin of the power chip D1 respectively.

[0036] Specifically, in this embodiment, the model of the NPN transistor V1 is LMBT4401LT1G, the model of the NMOS tube V2 is IRLML6401, the model of the diode V3 is 1N1D4148, the signal of the voltage reference chip D2 is TLVH431IDBZR, the resistance value of the resistor R1 is 3KΩ, the resistance value of the resistor R2 is 10KΩ, the resistance value of the resistor R3 is 100KΩ, the resistance value of the resistor R4 is 100Ω, the resistance value of the resistor R5 is 1KΩ, the resistance value of the resistor R6 is 6.2MΩ, the resistance value of the resistor R7 is 1.6MΩ, the resistance value of the resistor R8 is 100Ω, and the capacitance of the capacitor C1 is 0.1uF.

[0037] In this embodiment, the nickel-hydrogen battery charging overvoltage protection circuit includes a system power supply, a constant current charging circuit, an overvoltage protection circuit and a nickel-hydrogen battery pack; the system power supply is electrically connected to the constant current charging circuit, and the output of the constant current charging circuit is electrically connected to the overvoltage protection circuit and the positive electrode of the nickel-hydrogen battery pack. The system power supply and the constant current charging circuit are used to charge the nickel-hydrogen battery pack with the system power supply, and the overvoltage protection circuit is used to limit the voltage of the nickel-hydrogen battery pack to be lower than the rated value.

[0038] Specifically, the constant current charging circuit includes a power chip D1, and the first pin of the power chip D1 is connected to the constant current charging circuit. The constant current charging is divided into two parts: fast charging and slow charging. The fast charging circuit is composed of resistor R1, resistor R2, resistor R3, resistor R4, NPN transistor V1 and NMOS tube V2. CHARGE is the fast charging control state interface. In addition, the interface is connected to the base of NPN transistor V1 through current limiting resistor R1, and the collector of NPN transistor V1 is connected to the gate of NMOS tube V2 through the slow charging path through current limiting resistor R5 to power the nickel-hydrogen battery. The second pin of the power chip D1 is connected to the positive electrode of the nickel-hydrogen battery BATTERY1, and the third pin of the power chip D1 is connected to the main power supply through diode V3; the overvoltage protection circuit includes a voltage reference chip D2. The first pin of the voltage reference chip D2 is connected to resistor R6 and resistor R7, the second pin of the voltage reference chip D2 is connected to the positive electrode of the nickel-hydrogen battery BATTERY1 through resistor R8, and the third pin of the voltage reference chip D2 is connected to the reference ground.

[0039] In this embodiment, the battery charging voltage protection value is set to 6V.

[0040] Specifically, the voltage difference between the 1st and 2nd pins of the power chip D1 in the constant current charging circuit is 5V. For the fast charging circuit, when the CHARGE terminal is at a high level, the NPN transistor V1 is turned on, so that the gate voltage of the NMOS tube V2 is pulled down. At this time, the NMOS tube V2 is turned on, and the output current is theoretically 50mA through the current limiting resistor R4 with a resistance of 100Ω. For the slow charging circuit, the 5V voltage is directly across the current limiting resistor R5. At this time, the output current theoretical value is 5mA.

[0041] The reference terminal voltage of the 1st pin of the voltage reference chip D2 in the battery charging voltage protection circuit is divided by resistors R6 and R7. When the resistance values ​​of resistors R6 and R7 are 6.2MΩ and 1.6MΩ respectively, when the battery voltage is less than 6.045V, the output current of the constant current charging circuit supplies power to the nickel-hydrogen battery pack; when the battery voltage is greater than 6.045V, the 2nd and 3rd pins of the voltage reference chip D2 will be turned on. At this time, the output current of the constant current charging circuit will mainly pass through the conduction path of the voltage reference chip D2, thereby stopping powering the nickel-hydrogen battery pack.

[0042] Compared with the prior art, the nickel-hydrogen battery charging overvoltage protection circuit described in the above embodiment currently adopts the design of parallel voltage stabilizing diodes to prevent nickel-hydrogen battery overvoltage charging. However, the working voltage range of the voltage stabilizing diode is large, and it is difficult to maintain a relatively accurate voltage stabilizing value for batch products, resulting in poor overvoltage charging protection effect of existing products. The utility model has a simple structure, a convenient process, and a low cost. The designed constant current charging circuit is used to charge the nickel-hydrogen battery with the system power supply, and the designed overvoltage protection circuit is used to prevent the charging voltage of the nickel-hydrogen battery from being higher than the rated value, which solves the problem that the existing overvoltage protection circuit is not accurate enough in voltage stabilization and the overvoltage protection effect is poor. In addition, the utility model can more flexibly adjust the battery voltage limit, and has higher stability and faster response speed.

[0043] Obviously, the embodiments described above are only preferred embodiments of the utility model, rather than all embodiments. The preferred embodiments of the utility model are given in the accompanying drawings, but they do not limit the patent scope of the utility model. The utility model can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the utility model more thorough and comprehensive. Although the utility model is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to replace some of the technical features therein with equivalents. Any equivalent structure made using the contents of the utility model specification and the accompanying drawings, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the utility model.

Claims

1. A nickel-hydrogen battery charging overvoltage protection circuit, characterized in that: include: An electrically connected constant current charging circuit and an overvoltage protection circuit; The constant current charging circuit includes a power chip D1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, an NPN transistor V1, an NMOS transistor V2 and a diode V3. One end of the resistor R1 and the resistor R2 are connected to the fast charge control state interface CHARGE, the other end of the resistor R2 is grounded, the other end of the resistor R1 is connected to the base of the NPN transistor V1, the collector of the NPN transistor V1 is connected to one end of the resistor R3 and the gate of the NMOS transistor V2, the emitter of the NPN transistor V1 is grounded, the drain of the NMOS transistor V2 is connected to one end of the resistor R4, the source of the NMOS transistor V2 and one end of the resistor R5 are connected to the first pin of the power chip D1, the cathode of the diode V3 is connected to the other end of the resistor R3 and the third pin of the voltage chip D1, and the anode of the diode V3 is connected to the main power supply V13P0; The overvoltage protection circuit includes a voltage reference chip D2, a nickel-hydrogen battery BATTERY1, a resistor R6, a resistor R7 and a resistor R8. The other end of the resistor R4 is connected to the nickel-hydrogen battery BATTERY1, one end of the resistor R6 and one end of the resistor R8 respectively, and the other end of the nickel-hydrogen battery BATTERY1 is grounded. The other end of the resistor R5 is connected to the positive electrode of the nickel-hydrogen battery BATTERY1, one end of the resistor R6 and one end of the resistor R8 respectively. The other end of the resistor R6 is connected to the resistor R7 and the first pin of the voltage reference chip D2 respectively. One end of the resistor R8 is also connected to the second pin of the power chip D1. The other end of the resistor R8 is connected to the second pin of the voltage reference chip D2. The other end of the resistor R7 and the third pin of the voltage reference chip D2 are both grounded.

2. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 1, characterized in that: It also includes a capacitor C1, one end of which is connected to the cathode of the diode V3, one end of the resistor R3, and the third pin of the power chip D1 respectively.

3. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 1, characterized in that: The model of the NPN transistor V1 is LMBT4401LT1G.

4. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 1, characterized in that: The model of the NMOS tube V2 is IRLML6401.

5. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 1, characterized in that: The model of the diode V3 is 1N1D4148.

6. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 1, characterized in that: The signal of the voltage reference chip D2 is TLVH431IDBZR.

7. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 1, characterized in that: The resistance value of the resistor R1 is 3KΩ, the resistance value of the resistor R2 is 10KΩ, the resistance value of the resistor R3 is 100KΩ, the resistance value of the resistor R4 is 100Ω, the resistance value of the resistor R5 is 1KΩ, the resistance value of the resistor R6 is 6.2MΩ, the resistance value of the resistor R7 is 1.6MΩ, and the resistance value of the resistor R8 is 100Ω.

8. A nickel-hydrogen battery charging overvoltage protection circuit according to claim 2, characterized in that: The capacitance of the capacitor C1 is 0.1uF.

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