CN212849938U

CN212849938U - A charge-discharge protection circuit for BMS

Info

Publication number: CN212849938U
Application number: CN202021936110.6U
Authority: CN
Inventors: 魏巍; 潘文武
Original assignee: Shenzhen Times Energy Technology Co ltd
Current assignee: Shenzhen Times Energy Technology Co ltd
Priority date: 2020-09-04
Filing date: 2020-09-04
Publication date: 2021-03-30
Anticipated expiration: 2030-09-04

Abstract

A charge and discharge protection circuit for a BMS includes a charge and discharge management controller, a load switching circuit, a charge protection energy storage power supply, a secondary battery charging first unit, and a secondary battery charging second unit. The secondary battery charging first unit, the secondary battery charging second unit and the charging protection energy storage battery are sequentially connected in series between two input ends of an external charging power supply. The charging and discharging management controller is respectively connected with the load switching circuit, the secondary battery charging first unit and the secondary battery charging second unit and used for sending a first switching electric signal or a second switching electric signal to the load switching circuit, and the load switching circuit responds to the first switching electric signal or the second switching electric signal to connect the load with the secondary battery charging first unit or the secondary battery charging second unit, so that the BMS supports both the same-port-board charging mode and the different-port-board charging mode, and the switching control protection of the BMC system on the overvoltage or overcurrent of the battery in the charging and discharging process is realized.

Description

A charge-discharge protection circuit for BMS

Technical Field

The application relates to the technical field of power supplies, in particular to a charge and discharge protection circuit for BMS.

Background

The secondary battery is also called as a rechargeable battery, and the secondary battery utilizes the reversibility of chemical reaction to form a new battery. Namely, after a chemical reaction is converted into electric energy, the chemical system can be repaired by using the electric energy, then the electric energy is converted into the electric energy by using the chemical reaction, and the charge-discharge cycle of the secondary battery can reach thousands of times to tens of thousands of times, so the secondary battery is more economical and practical compared with a dry battery. Lithium batteries have the highest energy density ratio and power density ratio among all secondary batteries, and thus are most widely used. However, the inherent characteristics of lithium battery materials cause severe performance degradation and even safety problems when overcharged, overdischarged and over-warmed. Without effective management of the lithium battery pack, the performance of the battery pack will quickly decay, eventually rendering the battery pack unusable. A Battery Management System (BMS) manages charging and discharging of a secondary Battery in view of the disadvantages of a small energy storage capacity, a short life span, a problem of series-parallel connection (different types of batteries have different characteristics), poor safety, and difficulty in estimating the electric quantity of the Battery. The BMS mainly aims to improve the utilization rate of the secondary battery, prevent the battery from being overcharged or overdischarged, extend the service life of the battery, and monitor the state of the battery. As battery management systems have evolved, other functions may also be added.

The BMS comprises a charging and discharging circuit for charging and discharging management protection of the battery, the general charging and discharging circuit is divided into a same-port board circuit and a different-port board circuit, the same-port board circuit refers to the fact that charging and discharging share one interface, and charging and discharging are protected. The different-port plate circuit is characterized in that a charging wire and a discharging wire are separated, the charging port is protected from over-charging when only charging, and the discharging port is protected from over-discharging when discharging. In order to improve the compatibility of the BMS control board, it is required to design a battery management system supporting both the same board circuit and the different board circuit.

Disclosure of Invention

The application provides a charge-discharge protection circuit for BMS solves battery management system's not enough among the prior art.

According to a first aspect, an embodiment provides a charge and discharge protection circuit for a BMS, comprising a charge and discharge management controller, a load switching circuit, a charge protection energy storage power supply, a secondary battery charging first unit, a secondary battery charging second unit, a power supply first terminal and a power supply second terminal; the first end and the second end of the power supply are used for connecting an external charging power supply;

the charge and discharge management controller is connected with the secondary battery charging first unit, the secondary battery charging second unit and the load switching circuit and is used for respectively sending a first switching electric signal, a second switching electric signal, a first switching electric signal and a second switching electric signal to the secondary battery charging first unit, the secondary battery charging second unit and the load switching circuit;

the first secondary battery charging unit comprises a first shell capable of accommodating a secondary battery, and the first shell is provided with a first connecting end, a second connecting end and a charging and discharging control signal connecting end; the secondary battery charging first unit is used for charging or discharging the received secondary battery in response to the first switching electric signal; the first connection end of the secondary battery charging first unit is connected with the first connection end of the power supply, the second connection end of the secondary battery charging first unit is connected with the secondary battery charging second unit, and the charge-discharge control signal connection end of the secondary battery charging first unit is connected with the charge-discharge management controller;

the secondary battery charging second unit comprises a second shell capable of accommodating a secondary battery, and the second shell is provided with a first connecting end, a second connecting end and a charging and discharging control signal connecting end; the secondary battery charging second unit is used for charging or discharging the received secondary battery in response to the second switching electric signal; the first connecting end of the secondary battery charging second unit is connected with the second connecting end of the secondary battery charging first unit, the second connecting end of the secondary battery charging second unit is connected with the charging protection energy storage power supply, and the charging and discharging control signal connecting end of the secondary battery charging second unit is connected with the charging and discharging management controller; the load comprises a first connecting end and a second connecting end and is used as a load; the first connecting end of the load is connected with the second end of the power supply, and the second connecting end of the load is connected with the load switching circuit; the load switching circuit comprises a first connecting end, a second connecting end, a third connecting end and a switching signal receiving end; the first connecting end of the load switching circuit is connected with the second connecting end of the load, the second connecting end of the load switching circuit is connected with the first connecting end of the secondary battery charging first unit, the third connecting end of the load switching circuit is connected with the second connecting end of the secondary battery charging second unit, and the switching signal receiving end of the load switching circuit is connected with the charge and discharge management controller; the load switching circuit is used for responding to the first switching electric signal or the second switching electric signal to connect the second connecting end of the load with the first connecting end of the secondary battery charging first unit or the second connecting end of the secondary battery charging second unit.

Further, the first secondary battery charging unit further comprises a first charging and discharging switch circuit and a first secondary battery pack connecting device which are respectively arranged on the first shell; the secondary battery pack first connecting means for housing the secondary battery to charge or discharge the housed secondary battery; the first connecting device of the secondary battery pack comprises a first connecting end and a second connecting end, the first connecting end of the first connecting device of the secondary battery pack is connected with the first charge-discharge switch circuit, and the second connecting end of the first connecting device of the secondary battery pack is connected with the second connecting end of the first shell;

the first charging and discharging switch circuit comprises a first connecting end, a second connecting end and a third connecting end, the first connecting end of the first charging and discharging switch circuit is connected with the first connecting end of the first shell, the second connecting end of the first charging and discharging switch circuit is connected with the charging and discharging control signal connecting end of the first shell, and the third connecting end of the first charging and discharging switch circuit is connected with the first connecting end of the first connecting device of the secondary battery pack; the first charge-discharge switch circuit is used for responding to the first switching electric signal and connecting the first connecting end and the third connecting end of the first charge-discharge switch circuit so as to connect the first connecting end of the first connecting device of the secondary battery pack with the first connecting end of the first shell.

Further, the first shell is also provided with a current monitoring connecting end which is connected with the charge and discharge management controller; the secondary battery charging first unit further comprises a first current monitoring circuit arranged on the first shell; the first current monitoring circuit comprises a first connecting end, a second connecting end and a third connecting end; the first connection end of the first current monitoring circuit is connected with the third connection end of the first charge-discharge switch circuit, the second connection end of the first current monitoring circuit is connected with the current monitoring connection end of the first shell, and the third connection end of the first current monitoring circuit is connected with the first connection end of the first connection device of the secondary battery pack; the first current monitoring circuit is used for monitoring the charging current of the first charging unit of the secondary battery and sending a monitoring electric signal of the charging current obtained through monitoring to the charging and discharging management controller.

Further, the first current monitoring circuit includes a charging alloy resistor.

Further, the secondary battery charging second unit further comprises a second charging and discharging switch circuit and a second connecting device of a secondary battery pack, which are respectively arranged on the second shell; the second connecting device of the secondary battery pack is used for accommodating the secondary battery so as to charge or discharge the accommodated secondary battery; the second connecting device of the secondary battery pack comprises a first connecting end and a second connecting end, the first connecting end of the second connecting device of the secondary battery pack is connected with the second charge-discharge switch circuit, and the second connecting end of the second connecting device of the secondary battery pack is connected with the second connecting end of the second shell;

the second charge-discharge switch circuit comprises a first connecting end, a second connecting end and a third connecting end, the first connecting end of the second charge-discharge switch circuit is connected with the first connecting end of the second shell, the second connecting end of the second charge-discharge switch circuit is connected with the charge-discharge control signal connecting end of the second shell, and the third connecting end of the second charge-discharge switch circuit is connected with the first connecting end of the second connecting device of the secondary battery pack; the second charge-discharge switch circuit is used for responding to the second switching electric signal and connecting the first connecting end and the third connecting end of the second charge-discharge switch circuit so as to connect the first connecting end of the second connecting device of the secondary battery pack with the first connecting end of the second shell.

Further, the second shell is also provided with a current monitoring connecting end which is connected with the charge and discharge management controller; the secondary battery charging second unit further comprises a second current monitoring circuit arranged on the second shell; the second current monitoring circuit comprises a first connecting end, a second connecting end and a third connecting end; the first connecting end of the second current monitoring circuit is connected with the third connecting end of the second charge-discharge switch circuit, the second connecting end of the second current monitoring circuit is connected with the current monitoring connecting end of the second shell, and the third connecting end of the second current monitoring circuit is connected with the first connecting end of the second connecting device of the secondary battery pack; the second current monitoring circuit is used for monitoring the charging current of the secondary battery charging second unit and sending a monitoring electric signal of the charging current obtained through monitoring to the charging and discharging management controller.

Further, the second current monitoring circuit includes a charging alloy resistance.

Further, the charge and discharge management controller is further configured to obtain the monitoring electrical signal sent by the first current monitoring circuit or the second current monitoring circuit;

the charge and discharge management controller is further configured to send a third switching signal to the first charge and discharge switch circuit when the obtained monitoring signal sent by the first current monitoring circuit is greater than a first preset value, and the first charge and discharge switch circuit is further configured to disconnect a first connection end and a third connection end of the first charge and discharge switch circuit in response to the third switching signal;

the charge and discharge management controller is further configured to send a fourth switching electrical signal to the second charge and discharge switching circuit when the obtained monitoring electrical signal sent by the second current monitoring circuit is greater than a second preset value, and the second charge and discharge switching circuit is further configured to disconnect a first connection end and a third connection end of the second charge and discharge switching circuit in response to the fourth switching electrical signal.

Further, the charge and discharge management controller is also used for responding to a same-port charge and discharge signal and sending a first switching signal to the load switching circuit;

and/or the charge and discharge management controller is also used for responding to a different port charge and discharge signal and sending a second switching signal to the load switching circuit.

Further, the charging protection energy storage power supply comprises a lithium iron phosphate battery.

A charge and discharge protection circuit for a BMS according to the above-described embodiments includes a charge and discharge management controller, a load switching circuit, a charge protection energy storage power source, a secondary battery charging first unit, and a secondary battery charging second unit. The secondary battery charging first unit, the secondary battery charging second unit and the charging protection energy storage battery are sequentially connected in series between two input ends of an external charging power supply. The load is connected between the load switching circuit and one input end of the external charging power supply. The load switching circuit is connected with the secondary battery charging first unit, the secondary battery charging second unit and the load respectively. The charging and discharging management controller is respectively connected with the load switching circuit, the secondary battery charging first unit and the secondary battery charging second unit and used for sending a first switching electric signal or a second switching electric signal to the load switching circuit, and the BMS supports both the same-port-board charging mode and the different-port-board charging mode as the load switching circuit responds to the first switching electric signal or the second switching electric signal to connect the load with the secondary battery charging first unit or the secondary battery charging second unit.

Drawings

FIG. 1 is a schematic diagram illustrating a structural connection of a charge/discharge protection circuit according to an embodiment;

fig. 2 is a connection diagram of a charge/discharge protection circuit structure in an embodiment.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.

Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.

The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).

In an embodiment of the present invention, the disclosed charge and discharge protection circuit for a BMS includes a load switching circuit connected to a secondary battery charging first unit, a secondary battery charging second unit, and a load, respectively, such that the BMS supports both a same-port board charging mode and a different-port board charging mode since the load switching circuit connects the load to the secondary battery charging first unit or the secondary battery charging second unit in response to a first switching electric signal or a second switching electric signal from a charge and discharge management controller.

Example one

Referring to fig. 1, a schematic connection diagram of a charge and discharge protection circuit structure in an embodiment includes a charge and discharge management controller 7, a load 2, a load switching circuit 3, a charge protection energy storage power source 4, a first secondary battery charging unit 5, a second secondary battery charging unit 6, a first power source end, and a second power source end, where the first power source end and the second power source end are used to connect to an external charging power source. In one embodiment, the external charging power source includes a charger 1. The charge and discharge management controller 7 is connected to the secondary battery charging first unit 5, the secondary battery charging second unit 6, and the load switching circuit 3, and configured to send a first switching electrical signal, a second switching electrical signal, a first switching electrical signal, and a second switching electrical signal to the secondary battery charging first unit 5, the secondary battery charging second unit 6, and the load switching circuit 3, respectively. The secondary battery charging first unit 5 includes a first case capable of accommodating the secondary battery, the first case being provided with a first connection terminal, a second connection terminal, and a charge-discharge control signal connection terminal. The secondary battery charging first unit 5 is for charging or discharging the accommodated secondary battery in response to the first switching electric signal. The first connection end of the secondary battery charging first unit 5 is connected with the first connection end of the power supply, the second connection end of the secondary battery charging first unit 5 is connected with the secondary battery charging second unit 6, and the charge and discharge control signal connection end of the secondary battery charging first unit 5 is connected with the charge and discharge management controller 7. The secondary battery charging second unit 6 includes a second case capable of accommodating the secondary battery, the second case being provided with a first connection terminal, a second connection terminal, and a charge-discharge control signal connection terminal. The secondary battery charging second unit 6 is for charging or discharging the received secondary battery in response to a second switching electric signal. The first connecting end of the secondary battery charging second unit 6 is connected with the second connecting end of the secondary battery charging first unit 5, the second connecting end of the secondary battery charging second unit 6 is connected with the charging protection energy storage power supply 4, and the charging and discharging control signal connecting end of the secondary battery charging second unit 6 is connected with the charging and discharging management controller 7. The load 2 includes a first connection terminal and a second connection terminal for serving as a load of a charge and discharge protection circuit of the BMS. The first connection end of the load 2 is connected with the second end of the power supply, and the second connection end of the load 2 is connected with the load switching circuit 3. The load switching circuit 3 comprises a first connecting end, a second connecting end, a third connecting end and a switching signal receiving end, the first connecting end of the load switching circuit 3 is connected with the second connecting end of the load 2, the second connecting end of the load switching circuit 3 is connected with the first connecting end of the secondary battery charging first unit 5, the third connecting end of the load switching circuit 3 is connected with the second connecting end of the secondary battery charging second unit 6, and the switching signal receiving end of the load switching circuit 3 is connected with the charge-discharge management controller 7. The load switching circuit 3 is configured to connect the second connection terminal of the load 2 to the first connection terminal of the first secondary battery charging unit 5 or the second connection terminal of the second secondary battery charging unit 6 in response to the first switching electric signal or the second switching electric signal.

Referring to fig. 2, which is a schematic connection diagram of a charging and discharging protection circuit in an embodiment, the first unit 5 for charging a secondary battery further includes a first charging and discharging switch circuit 51 and a first connection device 53 for a secondary battery pack, which are respectively disposed on the first case 50. The secondary battery pack first connecting means is for receiving a secondary battery to charge or discharge the received secondary battery. The first secondary battery pack connecting device 53 includes a first connecting terminal and a second connecting terminal, the first connecting terminal of the first secondary battery pack connecting device 53 is connected to the first charge/discharge switch circuit 51, and the second connecting terminal of the first secondary battery pack connecting device 53 is connected to the second connecting terminal of the first housing 50. The first charge and discharge switch circuit 51 comprises a first connection end, a second connection end and a third connection end, the first connection end of the first charge and discharge switch circuit 51 is connected with the first connection end of the first shell 50, the second connection end of the first charge and discharge switch circuit 51 is connected with the charge and discharge control signal connection end of the first shell 50, and the third connection end of the first charge and discharge switch circuit 51 is connected with the first connection end of the secondary battery pack first connection device 53. The first charge and discharge switch circuit 51 is used for connecting the first connection terminal and the third connection terminal of the first charge and discharge switch circuit 51 in response to the first switching electrical signal to connect the first connection terminal of the secondary battery pack first connection device 53 with the first connection terminal of the first case 50. Further, the first housing 50 is further provided with a current monitoring connection terminal connected to the charge and discharge management controller 7. The secondary battery charging first unit 5 further includes a first current monitoring circuit 52 provided on the first housing 50. The first current monitoring circuit 52 includes a first connection end, a second connection end and a third connection end, the first connection end of the first current monitoring circuit 52 is connected with the third connection end of the first charge-discharge switch circuit 51, the second connection end of the first current monitoring circuit 52 is connected with the current monitoring connection end of the first casing 50, and the third connection end of the first current monitoring circuit 52 is connected with the first connection end of the secondary battery pack first connection device 53. The first current monitoring circuit 52 is configured to monitor a charging current of the secondary battery charging first unit 5, and send a monitoring electrical signal for monitoring the obtained charging current to the charge and discharge management controller 7. Further, the first current monitoring circuit 52 includes a charging alloy resistor connected in series between the third connection terminal of the first charge-discharge switch circuit 51 and the first connection terminal of the secondary battery pack first connection device 53.

In one embodiment, the second secondary battery charging unit 6 further includes a second charging/discharging switch circuit 61 and a second secondary battery pack connecting device 63, which are respectively disposed on the second housing 60. The secondary battery pack second connecting means 63 is for receiving a secondary battery to charge or discharge the received secondary battery. The second connection device 63 of the secondary battery pack includes a first connection end and a second connection end, the first connection end of the second connection device 63 of the secondary battery pack is connected with the second charge and discharge switch circuit 61, and the second connection end of the second connection device 63 of the secondary battery pack is connected with the second connection end of the second housing 60. The second charge and discharge switch circuit 61 comprises a first connection end, a second connection end and a third connection end, the first connection end of the second charge and discharge switch circuit 61 is connected with the first connection end of the second shell 60, the second connection end of the second charge and discharge switch circuit 61 is connected with the charge and discharge control signal connection end of the second shell 60, and the third connection end of the second charge and discharge switch circuit 61 is connected with the first connection end of the secondary battery pack second connection device 63. The second charge and discharge switch circuit 61 is used for responding to the second switching electrical signal to connect the first connection end and the third connection end of the second charge and discharge switch circuit 61 so as to connect the first connection end of the second connection device 63 of the secondary battery pack with the first connection end of the second casing 60. In one embodiment, the second housing 60 is further provided with a current monitoring connection terminal connected to the charge and discharge management controller 7, and the secondary battery charging second unit 6 further includes a second current monitoring circuit 62 disposed on the second housing 60. The second current monitoring circuit 62 includes a first connection end, a second connection end and a third connection end, the first connection end of the second current monitoring circuit 62 is connected with the third connection end of the second charge-discharge switch circuit 61, the second connection end of the second current monitoring circuit 62 is connected with the current monitoring connection end of the second casing 60, and the third connection end of the second current monitoring circuit 62 is connected with the first connection end of the second connection device 63 of the secondary battery pack. The second current monitoring circuit 62 is configured to monitor a charging current of the secondary battery charging second unit 6, and send a monitoring electrical signal for monitoring the obtained charging current to the charge and discharge management controller 7. In one embodiment, the second current monitoring circuit 62 includes a charging alloy resistor connected in series between the third connection terminal of the second charging/discharging switch circuit 61 and the first connection terminal of the second connection device 63 of the secondary battery pack.

In an embodiment, the charge and discharge management controller 7 is further configured to obtain the monitoring electrical signal sent by the first current monitoring circuit 52 or the second current monitoring circuit 62, the charge and discharge management controller 7 is further configured to send a third switching electrical signal to the first charge and discharge switch circuit 51 when the obtained monitoring electrical signal sent by the first current monitoring circuit 52 is greater than a first preset value, and the first charge and discharge switch circuit 51 is further configured to disconnect the first connection end and the third connection end of the first charge and discharge switch circuit 51 in response to the third switching electrical signal. The charge and discharge management controller 7 is further configured to send a fourth switching electrical signal to the second charge and discharge switching circuit 61 when the obtained monitoring electrical signal sent by the second current monitoring circuit 62 is greater than a second preset value, and the second charge and discharge switching circuit 61 is further configured to disconnect the first connection end and the third connection end of the second charge and discharge switching circuit 61 in response to the fourth switching electrical signal. In one embodiment, the charge and discharge management controller 7 is further configured to send a first switching signal to the load switching circuit 3 in response to a port charge and discharge signal. And/or the charge and discharge management controller 7 is further configured to send a second switching electrical signal to the load switching circuit 3 in response to a different port charge and discharge signal. In an embodiment, the charge and discharge management controller 7 includes an MCU control unit, and is configured to process an acquired monitoring electrical signal sent by the first current monitoring circuit or the second current monitoring circuit, and output a third switching electrical signal and a fourth switching electrical signal control signal. In one embodiment, the MCU control unit of the BMS uses Freescale' S MCUMC9S08PA as a main control chip, communicates with an Intersil lithium battery management chip ISL94212, monitors the voltage, battery temperature and charge-discharge current of the secondary battery contained in the first connection device of the secondary battery pack and the second connection device of the secondary battery pack, and performs intelligent balance management, thereby protecting the secondary battery and prolonging the service life of the secondary battery. Meanwhile, the SOC and the abnormal running state of the electric quantity are recorded, and the system adopts a modular design mode. The first current monitoring circuit and the second current monitoring circuit at the charging and discharging access position detect charging and discharging currents through alloy resistors, and voltage signals are obtained through operational amplification and output and sent to the MCU control unit. When the monitoring electric signal reaches a preset first preset threshold value or a preset second threshold value, the first charge-discharge switch circuit or the second charge-discharge switch circuit is controlled to be disconnected, the voltage output to the first connecting device of the secondary battery pack or the second connecting device of the secondary battery pack is closed, and the first charge-discharge switch circuit or the second charge-discharge switch circuit can be controlled to be connected through the MCU control unit.

In one embodiment, the charge protection energy storage power source 4 comprises a lithium iron phosphate battery.

In the embodiment of the application, a charging and discharging protection circuit for a BMS is disclosed, wherein a connection output mode on a control board and a connection mode between a charging power supply and a charging load are determined by adopting a cascade mode according to a same-port charging and discharging mode or a different-port charging and discharging mode of a user. The charging and discharging protection device comprises a charging and discharging management controller, a load switching circuit, a charging protection energy storage power supply, a secondary battery charging first unit and a secondary battery charging second unit. The secondary battery charging first unit, the secondary battery charging second unit and the charging protection energy storage battery are sequentially connected in series between two input ends of an external charging power supply. The load is connected between the load switching circuit and one input end of the external charging power supply. The load switching circuit is connected with the secondary battery charging first unit, the secondary battery charging second unit and the load respectively. The charging and discharging management controller is respectively connected with the load switching circuit, the secondary battery charging first unit and the secondary battery charging second unit and used for sending a first switching electric signal or a second switching electric signal to the load switching circuit, and the load switching circuit responds to the first switching electric signal or the second switching electric signal to connect the load with the secondary battery charging first unit or the secondary battery charging second unit, so that the BMS supports both the same-port-board charging mode and the different-port-board charging mode, and the switching control protection of the BMC system on the overvoltage or overcurrent of the battery in the charging and discharging process is realized.

The charge-discharge protection circuit is a new charge-discharge protection circuit which is designed on the basis of the existing independent same-port charge-discharge mode and different-port charge-discharge mode and can be compatible with each other, two connection wires are led out during the same-port control, and three connection wires are led out during the different-port control and are respectively connected with a charge power supply, a load and a secondary battery. When a user selects a same-port charging and discharging mode to charge and discharge the secondary battery, the load switching circuit responds to the first switching signal to connect the second connecting end of the load with the first connecting end of the secondary battery charging first unit. The first end of the power supply of the charge-discharge protection circuit is connected with the positive pole of the charging power supply, the second end of the power supply of the charge-discharge protection circuit is connected with the negative pole of the charging power supply, the BMC connects the positive pole of the charging power supply, the positive pole of the load and the total positive pole of the charge protection energy storage power supply together, and the negative pole of the charging power supply is directly connected with the negative pole of the load. When the BMC system performs charging operation, the charging current flows through the charging protection energy storage power supply, the secondary battery charging second unit, the secondary battery charging first unit, the load switching circuit and the negative electrode of the load current backflow charging power supply along the positive end of the charging power supply. The charging and discharging management controller controls the first charging and discharging switch circuit and the second charging and discharging switch circuit to be conducted, when charging current flows through the first current monitoring circuit and the second current monitoring circuit, certain voltage drop is generated on alloy resistors of the first current monitoring circuit and the second current monitoring circuit, the voltage drop electric signals are amplified through an operational amplifier circuit of the current monitoring circuit to obtain monitoring electric signals, the monitoring electric signals are output to the charging and discharging management controller, and when the voltage drop electric signals are larger than a first preset value, the charging and discharging management controller sends third switching electric signals and fourth switching electric signals to the first charging and discharging switch circuit and the second charging and discharging switch circuit to be disconnected. When the charging power supply in the BMC system is powered off, the secondary battery supplies power to the load to perform corresponding discharging work, discharging current flows through the anode of the secondary battery, the load switching circuit, the load and the charging protection energy storage power supply, and when the charging current is smaller than a preset value, the charging and discharging management controller controls the first charging and discharging switch circuit and the second charging and discharging switch circuit to be disconnected so as to play a role in discharging protection.

When a user selects a different-port charging and discharging mode to charge and discharge the secondary battery, the load switching circuit responds to the second switching electric signal to connect the load with the secondary battery charging second unit. When the BMC system performs charging work, the charging current is divided into two branches, one branch of the charging current flows back to the negative electrode of the charging power supply along the load, the load switching circuit, the negative electrode of the secondary battery, the positive electrode of the secondary battery, the first current monitoring circuit and the first charging and discharging switching circuit, and the other branch of the charging current flows back to the negative electrode of the charging power supply along the charging protection energy storage power supply, the second charging and discharging switching circuit, the second current monitoring circuit, the negative electrode of the secondary battery, the positive electrode of the secondary battery and the load, so that the charging current of the charging and discharging protection circuit of the BMC is equal to. When the charging power supply is disconnected, the secondary battery supplies power to the load, the charging and discharging management controller obtains monitoring electric signals according to the first current monitoring circuit and the second current monitoring circuit, compares the monitoring electric signals with a preset value, and controls the first charging and discharging switch circuit and the second charging and discharging switch circuit to be disconnected or connected according to a comparison result so as to achieve discharging protection.

The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.

Claims

1. A charge and discharge protection circuit for a BMS (battery management system) is characterized by comprising a charge and discharge management controller, a load switching circuit, a charge protection energy storage power supply, a secondary battery charging first unit, a secondary battery charging second unit, a power supply first end and a power supply second end; the first end and the second end of the power supply are used for connecting an external charging power supply;

the secondary battery charging second unit comprises a second shell capable of accommodating a secondary battery, and the second shell is provided with a first connecting end, a second connecting end and a charging and discharging control signal connecting end; the secondary battery charging second unit is used for charging or discharging the received secondary battery in response to the second switching electric signal; the first connecting end of the secondary battery charging second unit is connected with the second connecting end of the secondary battery charging first unit, the second connecting end of the secondary battery charging second unit is connected with the charging protection energy storage power supply, and the charging and discharging control signal connecting end of the secondary battery charging second unit is connected with the charging and discharging management controller;

the load comprises a first connecting end and a second connecting end and is used as a load; the first connecting end of the load is connected with the second end of the power supply, and the second connecting end of the load is connected with the load switching circuit;

the load switching circuit comprises a first connecting end, a second connecting end, a third connecting end and a switching signal receiving end; the first connecting end of the load switching circuit is connected with the second connecting end of the load, the second connecting end of the load switching circuit is connected with the first connecting end of the secondary battery charging first unit, the third connecting end of the load switching circuit is connected with the second connecting end of the secondary battery charging second unit, and the switching signal receiving end of the load switching circuit is connected with the charge and discharge management controller; the load switching circuit is used for responding to the first switching electric signal or the second switching electric signal to connect the second connecting end of the load with the first connecting end of the secondary battery charging first unit or the second connecting end of the secondary battery charging second unit.

2. The charge and discharge protection circuit according to claim 1, wherein the first unit for charging the secondary battery further comprises a first charge and discharge switch circuit and a first connection device for the secondary battery pack, respectively disposed on the first housing; the secondary battery pack first connecting means for housing the secondary battery to charge or discharge the housed secondary battery; the first connecting device of the secondary battery pack comprises a first connecting end and a second connecting end, the first connecting end of the first connecting device of the secondary battery pack is connected with the first charge-discharge switch circuit, and the second connecting end of the first connecting device of the secondary battery pack is connected with the second connecting end of the first shell;

3. The charge and discharge protection circuit according to claim 2, wherein the first housing is further provided with a current monitoring connection terminal connected to the charge and discharge management controller; the secondary battery charging first unit further comprises a first current monitoring circuit arranged on the first shell; the first current monitoring circuit comprises a first connecting end, a second connecting end and a third connecting end; the first connection end of the first current monitoring circuit is connected with the third connection end of the first charge-discharge switch circuit, the second connection end of the first current monitoring circuit is connected with the current monitoring connection end of the first shell, and the third connection end of the first current monitoring circuit is connected with the first connection end of the first connection device of the secondary battery pack; the first current monitoring circuit is used for monitoring the charging current of the first charging unit of the secondary battery and sending a monitoring electric signal of the charging current obtained through monitoring to the charging and discharging management controller.

4. The charge and discharge protection circuit of claim 3, wherein the first current monitoring circuit comprises a charging alloy resistor.

5. The charge and discharge protection circuit according to claim 3, wherein said secondary battery charging second unit further comprises a second charge and discharge switch circuit and a secondary battery pack second connecting means respectively provided on said second case; the second connecting device of the secondary battery pack is used for accommodating the secondary battery so as to charge or discharge the accommodated secondary battery; the second connecting device of the secondary battery pack comprises a first connecting end and a second connecting end, the first connecting end of the second connecting device of the secondary battery pack is connected with the second charge-discharge switch circuit, and the second connecting end of the second connecting device of the secondary battery pack is connected with the second connecting end of the second shell;

6. The charge and discharge protection circuit according to claim 5, wherein the second housing is further provided with a current monitoring connection terminal connected to the charge and discharge management controller; the secondary battery charging second unit further comprises a second current monitoring circuit arranged on the second shell; the second current monitoring circuit comprises a first connecting end, a second connecting end and a third connecting end; the first connecting end of the second current monitoring circuit is connected with the third connecting end of the second charge-discharge switch circuit, the second connecting end of the second current monitoring circuit is connected with the current monitoring connecting end of the second shell, and the third connecting end of the second current monitoring circuit is connected with the first connecting end of the second connecting device of the secondary battery pack; the second current monitoring circuit is used for monitoring the charging current of the secondary battery charging second unit and sending a monitoring electric signal of the charging current obtained through monitoring to the charging and discharging management controller.

7. The charge and discharge protection circuit of claim 6 wherein said second current monitoring circuit comprises a charging alloy resistor.

8. The charging and discharging protection circuit of claim 6, wherein the charging and discharging management controller is further configured to obtain the monitoring electrical signal sent by the first current monitoring circuit or the second current monitoring circuit;

9. The charge and discharge protection circuit of claim 6 wherein the charge and discharge management controller is further configured to send a first switching signal to the load switching circuit in response to a port charge and discharge signal;

10. The charge-discharge protection circuit according to any of claims 1 to 9, wherein said charge-protection energy storage power source comprises a lithium iron phosphate battery.