CN214755651U

CN214755651U - Secondary overcharge protection circuit for lithium battery protection board after overcharge protection failure

Info

Publication number: CN214755651U
Application number: CN202120975508.9U
Authority: CN
Inventors: 王泽伟; 梁荣林; 刘亚东; 吴光辉; 韩玉秀
Original assignee: Chongqing Meishun Electronic Technology Co ltd
Current assignee: Chongqing Meishun Electronic Technology Co ltd
Priority date: 2021-05-08
Filing date: 2021-05-08
Publication date: 2021-11-16
Anticipated expiration: 2031-05-08

Abstract

The utility model discloses a lithium battery protection shield overcharge protection circuit of secondary after becoming invalid has added logic circuit and silicon controlled rectifier on original circuit basis, and silicon controlled rectifier is controlled by logic circuit, when logic circuit detects the battery and totally presses when exceeding the settlement voltage, at first closes N type MOS pipe that discharges, then opens silicon controlled rectifier, with the positive pole and the negative pole short circuit of charger, just so can prevent to form the return circuit between charger and the battery. At this moment, the output of the charger is short-circuited, the short-circuit protection of the charger is triggered, and the charging process is finished.

Description

Secondary overcharge protection circuit for lithium battery protection board after overcharge protection failure

Technical Field

The utility model relates to a lithium battery charging technology field especially relates to a secondary overcharge protection circuit after lithium battery protection board overcharge protection became invalid.

Background

With the strong support of the state on the new energy field and the continuous maturation of the technology in the new energy field. The market for various products using lithium batteries as power sources is rapidly growing, especially in the field of two-wheeled vehicles.

However, the problem is also caused by the fact that the power lithium battery has high energy density and various specifications, so that the situation that the electric vehicle is ignited and burnt frequently occurs in recent years, and most of the situation is caused by overcharge due to the fact that the power lithium battery cannot be effectively protected during charging. Therefore, the safety of charging is a crucial part for ensuring the safe use of the lithium battery. How to ensure the charging safety is that firstly, a user uses a charger special for a manufacturer when using the battery. And the lithium battery protection board is ensured not to fail. Charging safety can only be guaranteed if these two conditions are met simultaneously.

However, in practice, the user often uses the charger in a mess. For example, a battery of 48V originally for pursuing a charging speed is charged by an 84V charger. Such high-voltage charge/discharge is large in current and high in charge voltage. Therefore, the battery is abnormally aged, the lithium battery protection plate is possibly invalid, and the battery is overcharged or even explodes to cause fire once the protection plate is invalid.

At present, the main current overcharge protection in the market is only one-level overcharge protection, and the on-off is controlled by an MOS transistor completely, as shown in fig. 1, during charging, current flows into a battery from a positive electrode P + end of a charger P1 and then flows back to a charger-shaped P1 from a negative electrode P-end to form a charging loop, wherein a discharging N-type MOS transistor Q1 controls the discharging loop, and a charging N-type MOS transistor Q2 controls the charging loop. When overcharge occurs, the charging N-type MOS transistor Q2 is turned off, and the charging circuit is cut off to stop charging. However, if the charging N-type MOS transistor Q2 breaks down, the charging loop cannot be disconnected, which may cause the battery to be overcharged. And once an out-of-specification charger overcharge protection MOS tube is used, the over-charge protection MOS tube is easily broken down to cause charging protection failure, and the over-charge of the battery is also caused necessarily.

Therefore, the technical personnel in the field are dedicated to develop a secondary overcharge protection circuit with good protection effect after the overcharge protection of the lithium battery protection board fails.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention provides a method for manufacturing a semiconductor device.

In order to achieve the above object, the present invention provides a secondary overcharge protection circuit after overcharge protection failure of a lithium battery protection board, which comprises a lithium battery charging protection chip U1, a plurality of serially connected lithium batteries BT1, a resistor R12, a discharging N-type MOS transistor Q1, a charging N-type MOS transistor Q2 and a charger P1, wherein the lithium battery charging protection chip U1 is connected to the positive electrode of the lithium battery BT1, the two ends of the resistor R12, the gate of the discharging N-type MOS transistor Q1 and the gate of the charging N-type MOS transistor Q2, the positive electrode of the lithium battery BT1 is connected to the positive electrode of the charger P1, the negative electrode of the lithium battery BT1 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to the source of the discharging N-type MOS transistor Q1, the drain of the discharging N-type MOS transistor Q1 is connected to the drain of the charging N-type MOS transistor Q2, and the source of the charging N-type MOS transistor Q2 is connected to the negative electrode of the charger P1, the lithium battery charging protection circuit further comprises a logic circuit LC and a silicon controlled rectifier Q3, wherein one end of the logic circuit LC is connected with the lithium battery charging protection chip U1 and the grid electrode of the discharging N-type MOS tube Q1, and the other end of the logic circuit LC is connected with the control electrode of the silicon controlled rectifier Q3; the anode of the silicon controlled rectifier Q3 is connected with the anode of the charger P1, and the cathode of the silicon controlled rectifier Q3 is connected with the cathode of the charger P1.

The utility model has the advantages that: the utility model discloses a lithium battery protection board overcharge protection circuit after becoming invalid secondary has added logic circuit and silicon controlled rectifier on original circuit basis, and silicon controlled rectifier is controlled by logic circuit, when logic circuit detected the battery and totally pressed when exceeding the settlement voltage, at first closed discharge N type MOS pipe, then opened silicon controlled rectifier, with the positive pole and the negative pole short circuit of charger, just so can prevent to form the return circuit between charger and the battery. At this moment, the output of the charger is short-circuited, the short-circuit protection of the charger is triggered, and the charging process is finished.

Drawings

FIG. 1 is a schematic diagram of a prior art lithium battery charging circuit;

fig. 2 is a schematic circuit diagram of the present invention.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and examples, wherein it is noted that, in the description of the invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular manner, and therefore should not be construed as limiting the present invention. The terms "discharge," "charge," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

As shown in fig. 2, a secondary overcharge protection circuit after overcharge protection failure of a lithium battery protection board comprises a lithium battery charging protection chip U1, a plurality of lithium batteries BT1 connected in series, a resistor R12, a discharging N-type MOS transistor Q1, a charging N-type MOS transistor Q2 and a charger P1, wherein the lithium battery charging protection chip U1 is connected with the positive electrode and the negative electrode of the lithium battery BT1, both ends of the resistor R12, the gate of the discharging N-type MOS transistor Q1 and the gate of the charging N-type MOS transistor Q2 respectively, the positive electrode of the lithium battery BT1 is connected with the positive electrode P + end of the charger P1, the negative electrode of the lithium battery BT1 is connected with one end of the resistor R12, the other end of the resistor R12 is connected with the source of the discharging N-type MOS transistor Q1, the drain of the discharging N-type MOS transistor Q1 is connected with the drain of the charging N-type MOS transistor Q2, the drain of the charging N-type MOS transistor Q2 is connected with the negative electrode P-terminal of the charger P1, a logic circuit and a silicon controlled rectifier LC 3, one end of the logic circuit LC is connected with the lithium battery charging protection chip U1 and the grid electrode of the discharging N-type MOS tube Q1, and the other end of the logic circuit LC is connected with the control electrode of the silicon controlled rectifier Q3; the anode of the silicon controlled rectifier Q3 is connected with the positive pole P + end of the charger P1, and the cathode of the silicon controlled rectifier Q3 is connected with the negative pole P-end of the charger P1.

The secondary overcharge protection circuit is characterized in that a logic circuit LC and a silicon controlled rectifier Q3 are added on the basis of an original circuit, a silicon controlled rectifier Q3 is controlled by the logic circuit LC, when the logic circuit LC detects that the total pressure of a plurality of lithium batteries BT1 exceeds a set voltage [4.5V (ternary lithium batteries) x string number ] or [3.9V (lithium iron phosphate batteries) x string number ], a discharging N-type MOS (metal oxide semiconductor) tube is closed at first, then the silicon controlled rectifier Q3 is opened, and the positive electrode and the negative electrode of a charger P1 are short-circuited, so that a loop can be prevented from being formed between the charger P1 and the lithium batteries BT 1. At this time, the output of the charger P1 is short-circuited, the short-circuit protection of the charger is triggered, the charging process is finished, and then the charging N-type MOS transistor Q2 is failed and needs to be returned to a factory for treatment.

The foregoing has described in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions that can be obtained by a person skilled in the art through logic analysis, reasoning or limited experiments based on the prior art according to the concepts of the present invention should be within the scope of protection defined by the claims.

Claims

1. The secondary overcharge protection circuit after the overcharge protection failure of the lithium battery protection board comprises a lithium battery charging protection chip U1, a plurality of lithium batteries BT1 connected in series, a resistor R12, a discharging N-type MOS tube Q1, a charging N-type MOS tube Q2 and a charger P1, the lithium battery charging protection chip U1 is respectively connected with the positive electrode and the negative electrode of the lithium battery BT1, two ends of the resistor R12, the grid electrode of the discharging N-type MOS tube Q1 and the grid electrode of the charging N-type MOS tube Q2, the positive electrode of the lithium battery BT1 is connected with the positive electrode of the charger P1, the negative electrode of the lithium battery BT1 is connected with one end of the resistor R12, the other end of the resistor R12 is connected with the source electrode of the discharging N-type MOS tube Q1, the drain electrode of the discharging N-type MOS tube Q1 is connected with the drain electrode of the charging N-type MOS tube Q2, the source electrode of the charging N-type MOS tube Q2 is connected with the negative electrode of the charger P1, and the charging N-type MOS tube charging device is characterized in that: the lithium battery charging protection circuit further comprises a logic circuit LC and a silicon controlled rectifier Q3, wherein one end of the logic circuit LC is connected with the lithium battery charging protection chip U1 and the grid electrode of the discharging N-type MOS tube Q1, and the other end of the logic circuit LC is connected with the control electrode of the silicon controlled rectifier Q3; the anode of the silicon controlled rectifier Q3 is connected with the anode of the charger P1, and the cathode of the silicon controlled rectifier Q3 is connected with the cathode of the charger P1.