CN216720940U

CN216720940U - Charging and discharging circuit, power supply and electric vehicle

Info

Publication number: CN216720940U
Application number: CN202121761013.2U
Authority: CN
Inventors: 曾龙贵; 刘金成; 刘建华
Original assignee: Ningbo Eve Chuang Energy Lithium Battery Co ltd
Current assignee: Ningbo Eve Chuang Energy Lithium Battery Co ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2022-06-10
Anticipated expiration: 2031-07-30

Abstract

The utility model discloses a charging and discharging circuit, a power supply and an electric vehicle. The charging and discharging circuit comprises a control unit, a secondary protection unit and a three-terminal fuse. The control unit is provided with a first voltage sampling end and a charge-discharge control end. The secondary protection unit is provided with a second voltage sampling end and a protection control end, and the three-end fuse is connected in the charge-discharge loop in series. The first voltage sampling end is used for collecting the voltage of the battery, the charging and discharging control end is connected with the control end of a charging and discharging MOS tube connected in series in the charging and discharging loop, and the control unit is used for adjusting the on-off state of the charging and discharging MOS tube according to the sampling value of the first voltage sampling end. The second voltage sampling end is used for collecting the voltage of the battery, and the secondary protection unit is used for outputting a signal for controlling the fusing of the three-terminal fuse through the protection control end according to the sampling value of the second voltage sampling end.

Description

Charging and discharging circuit, power supply and electric vehicle

Technical Field

The embodiment of the utility model relates to the technology of electric vehicles, in particular to a charging and discharging circuit, a power supply and an electric vehicle.

Background

The battery is a power source of the electric vehicle, and in order to ensure the use safety of the battery, a control circuit and a safety strategy are correspondingly configured to monitor the working state of the battery, and when the battery is abnormal in overcurrent, overvoltage and the like, the battery is prevented from being damaged, fired or exploded by executing the safety strategy.

In order to match with the marketing strategy of the electric vehicle, the battery is designed to meet the safety requirements of the selling destination while meeting the safety requirements. For example, if the electric vehicle is sold in Europe and America, the battery should be designed to conform to UL/IEC62133 and pass the UL/IEC62133 safety test.

In order to achieve the above purpose, in the prior art, a set of charging MOS transistors is additionally connected in series in the original charging and discharging loop, so that the whole battery pack conforms to the safety certification test. The circuit design method has the following defects: the safety control is realized only by controlling the charging and discharging MOS tube, and the secondary protection of the battery cannot be realized; for the electric vehicle which continuously discharges at 20A/30A and is in the same charge and discharge port, a group of charge and discharge MOS tubes with the same number are additionally connected in series, so that the whole vehicle cost is greatly increased.

SUMMERY OF THE UTILITY MODEL

The utility model provides a charging and discharging circuit, a power supply and an electric vehicle, which aim to effectively realize primary protection and secondary protection on a battery.

In a first aspect, an embodiment of the present invention provides a charge and discharge circuit, including a control unit, a secondary protection unit, and a three-terminal fuse;

the control unit is provided with a first voltage sampling end and a charge-discharge control end, the secondary protection unit is provided with a second voltage sampling end and a protection control end, and the three-terminal fuse is connected in series in the charge-discharge loop;

the first voltage sampling end is used for collecting the voltage of a battery, the charge and discharge control end is connected with the control end of a charge and discharge MOS tube connected in series in a charge and discharge loop, and the control unit is used for controlling the on-off of the charge and discharge MOS tube and adjusting the on-off state of the charge and discharge MOS tube according to the sampling value of the first voltage sampling end;

the second voltage sampling end is used for collecting the voltage of the battery, and the secondary protection unit is used for outputting and controlling a signal for fusing the three-terminal fuse through the protection control end according to the sampling value of the second voltage sampling end.

Further, the secondary protection unit comprises a plurality of secondary protection modules;

the secondary protection unit comprises a plurality of secondary protection modules;

the secondary protection module is provided with a plurality of voltage sampling ends and an output end, the voltage sampling end of each secondary protection module is used as the second voltage sampling end, and the output end of each secondary protection module is used as the protection control end;

and the secondary protection module is used for independently collecting the voltage of a group of battery cells and independently outputting a signal for controlling the fusing of the three-terminal fuse when the detected voltage of the battery cells is abnormal.

Furthermore, one secondary protection module supplies power through one battery cell connected with the secondary protection module.

Furthermore, the battery is composed of 15 battery cores connected in series, and one secondary protection module is used for collecting the voltages of the 5 battery cores.

Further, the current detection device also comprises a current detection resistor, and the control unit is also provided with a current detection end;

the detection resistor is connected in series in the charge-discharge loop, and the control unit is connected with the current detection resistor through the current detection end.

Further, the device also comprises a temperature sensor, and the control unit is also provided with a temperature detection end;

the temperature sensor is connected with the temperature detection end and used for collecting the temperature of the battery.

Furthermore, the control unit is also provided with a pre-charging and discharging control end;

and the pre-charge and discharge control end is connected with a pre-charge and discharge MOS tube which is connected in series in the charge and discharge loop.

Further, the control unit adopts a model of BQ76952, and the secondary protection module adopts a model of SH 367215.

In a second aspect, an embodiment of the present invention further provides a power supply, including a battery and the charging and discharging circuit described in the embodiment of the present invention;

the charging and discharging circuit is used for charging and discharging control of the battery and charging and discharging protection in the charging and discharging process.

In a third aspect, an embodiment of the present invention further provides an electric vehicle, which is equipped with the power supply described in the embodiment of the present invention.

Compared with the prior art, the utility model has the beneficial effects that: the charging and discharging circuit provided by the utility model comprises a control unit, a secondary protection unit and a three-terminal fuse, wherein primary protection in the charging and discharging process is realized through the control unit, and secondary protection is realized through the secondary protection unit. In the charge and discharge circuit, the control unit and the secondary protection unit are arranged to detect the voltage of the battery respectively, when the secondary protection unit detects that the voltage of the battery exceeds a set value, the three-terminal fuse is immediately controlled to be fused, the process of realizing secondary protection by the secondary protection unit does not depend on the control unit, the control unit and the secondary protection unit respectively play different roles, and safety protection aiming at the whole charge and discharge circuit can be effectively realized.

Drawings

FIG. 1 is a block diagram of a charging and discharging circuit in the embodiment;

FIG. 2 is a schematic diagram of a charging and discharging circuit in the embodiment;

FIG. 3 is a circuit schematic of the voltage acquisition function in an embodiment;

FIG. 4 is a schematic circuit diagram of the current collection function in the embodiment;

FIG. 5 is a schematic diagram of an auxiliary function circuit in an embodiment;

FIG. 6 is a schematic circuit diagram of the charge and discharge function in the embodiment;

FIG. 7 is a circuit diagram of a fuse function in an embodiment;

FIG. 8 is a schematic circuit diagram of a secondary protection function in an embodiment;

FIG. 9 is a pin diagram of BQ76952 in an embodiment;

fig. 10 is a SH367215 pin diagram in an embodiment.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the utility model and are not to be construed as limiting the utility model. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Example one

Fig. 1 is a block diagram of a charging and discharging circuit in an embodiment, and referring to fig. 1, the charging and discharging circuit includes a control unit 100, a secondary protection unit 200, and a three-terminal fuse 300.

The control unit 100 is configured with a first voltage sampling end and a charging and discharging control end, the secondary protection unit 200 is configured with a second voltage sampling end and a protection control end, and the three-terminal fuse 300 is connected in series in the charging and discharging loop.

The first voltage sampling end is used for collecting the voltage of the battery 2000, the charge and discharge control end is connected with the control end of the charge and discharge MOS tube 1000 which is connected in series in the charge and discharge loop, and the control unit 100 is used for controlling the on-off of the charge and discharge MOS tube 1000 and adjusting the on-off state of the charge and discharge MOS tube 1000 according to the sampling value of the first voltage sampling end.

The second voltage sampling terminal is used for collecting the voltage of the battery 2000, and the secondary protection unit 200 is used for outputting a signal for controlling the fusing of the three-terminal fuse 300 through the protection control terminal according to the sampling value of the second voltage sampling terminal.

Illustratively, the P + end and the P-end are used as connecting ends of the battery pack and used for connecting a load or a charger.

Exemplarily, in the present embodiment, the control unit 100 is specifically used for charge and discharge control of the battery 2000 and primary protection of the battery 2000 during the charge and discharge control of the battery, and the secondary protection unit 200 is used for secondary protection of the battery 2000.

As an implementation scheme, in this embodiment, in order to facilitate charge and discharge control, the charge and discharge MOS transistor 1000 is specifically divided into a charge MOS transistor and a discharge MOS transistor, and the working process of the charge and discharge circuit includes:

when the battery 2000 needs to be charged, the control unit 100 controls the conduction of the charging MOS transistor and the disconnection of the discharging MOS transistor, and if the charging current exceeds a certain value, the conduction of the discharging MOS transistor can be controlled, so that the charging capability is improved;

the control unit 100 monitors the voltage of the battery 2000, and if the voltage exceeds a first overvoltage protection threshold, the control unit 100 controls the charging MOS transistor to be turned off;

if the voltage of the battery recovers to be below the set overvoltage recovery value, the control unit 100 controls the charging MOS tube to recover conduction;

the secondary protection unit 200 monitors the voltage of the battery 2000, and if the voltage exceeds a second overvoltage protection threshold (the second overvoltage protection threshold may be greater than the first overvoltage protection threshold), the secondary protection unit 200 controls the three-terminal fuse 300 to be blown;

when the battery 2000 needs to discharge, the control unit 100 controls the conduction of the discharging MOS transistor and the turn-off of the charging MOS transistor, and if the discharging current exceeds a certain value, the conduction of the charging MOS transistor can be controlled, so that the discharging capability is improved;

the control unit 100 monitors the voltage of the battery 2000, and if the voltage is lower than a first undervoltage protection threshold, the control unit 100 controls the discharge MOS transistor to be turned off;

if the battery voltage recovers to be above the set under-voltage recovery value, the control unit 100 controls the discharging MOS transistor to recover conduction.

The charging and discharging circuit provided by the embodiment comprises a control unit, a secondary protection unit and a three-terminal fuse, wherein primary protection in the charging and discharging process is realized through the control unit, and secondary protection is realized through the secondary protection unit. In the charge and discharge circuit, the control unit and the secondary protection unit are arranged to detect the voltage of the battery respectively, when the secondary protection unit detects that the voltage of the battery exceeds a set value, the three-terminal fuse is immediately controlled to be fused, the process of realizing secondary protection by the secondary protection unit does not depend on the control unit, the control unit and the secondary protection unit respectively play different roles, and safety protection aiming at the whole charge and discharge circuit can be effectively realized.

Example two

For example, in this embodiment, the battery may be 3 to 16 strings of lithium batteries, the types of the control unit 100 and the secondary protection unit 200 are selected according to the types of the batteries, and the peripheral circuits of the chips are designed accordingly.

As an implementation example, if the battery is 15 strings of lithium batteries, the control unit 100 may use a BQ76952 chip, and the secondary protection unit 200 may use an SH367215 chip.

Illustratively, the BQ76952 is a protection control chip for 3 to 16 strings of lithium batteries, the SH367215 chip is a secondary protection chip for 3 to 5 strings of lithium batteries, and one BQ76952 and a plurality of SH367215 can be configured in the charge and discharge protection circuit.

Fig. 2 is a schematic diagram of a charging and discharging circuit in an embodiment, referring to fig. 2, a control unit 100(BQ76952) and four secondary protection modules 200-1 to 200-4(SH367215) are disposed in the charging and discharging circuit.

Referring to fig. 2, the charge/discharge circuit includes a charge MOS transistor Q1, a discharge MOS transistor Q2, a pre-charge MOS transistor Q3, a pre-discharge MOS transistor Q4, and a three-terminal fuse 300.

Illustratively, the charging MOS transistor Q1 and the discharging MOS transistor Q2 are NMOS transistors, and the pre-charging MOS transistor Q3 and the pre-discharging MOS transistor Q4 are PMOS transistors.

The positive electrode of the battery BAT is connected with the P + end of the battery pack through the three-terminal fuse 300, the charging MOS tube Q1 and the discharging MOS tube Q2, and the negative electrode of the battery BAT is connected with the P-end of the battery pack;

the positive electrode of the battery BAT is connected with the P + end of the battery pack through a pre-charging MOS tube Q3 and a pre-discharging MOS tube Q4 after passing through the three-terminal fuse 300;

the charging MOS transistor Q1 and the discharging MOS transistor Q2 are respectively connected to a charging/discharging control terminal of the control unit 100, and the pre-charging MOS transistor Q3 and the pre-discharging MOS transistor Q4 are respectively connected to a pre-charging/discharging control terminal of the control unit 100.

The voltage sampling terminal of the control unit 100 is connected to each electric core in the battery BAT.

The voltage sampling end of each secondary protection module is respectively connected with the corresponding battery cell, and the output end of each secondary protection module is connected with the control end of the three-terminal fuse 300 through the MOS tube Q5.

Referring to fig. 2, the charging and discharging circuit further includes a temperature sensor U1, the temperature sensor U1 is used for collecting the temperature of the battery BAT, and the output end of the temperature sensor U1 is connected to the temperature detection end of the control unit 100.

Referring to fig. 2, the charge and discharge circuit further includes a current detection resistor R1, the current detection resistor R1 is connected in series in the charge and discharge circuit, and the current detection terminals of the control unit 100 are respectively connected to two terminals of the current detection resistor R1.

Illustratively, the operation process of the charging and discharging circuit shown in fig. 2 includes:

when the battery BAT needs to be charged, the control unit 100 first controls the pre-charge MOS transistor Q3 to be turned on, and after a set condition is reached, controls the pre-charge MOS transistor Q3 to turn off the charge MOS transistor Q1 to be turned on (the charging current charges the battery BAT through a diode in the MOS transistor Q2 and the MOS transistor Q1);

the control unit 100 monitors the voltage, the current and the temperature of the battery BAT, and if the voltage exceeds a first overvoltage protection threshold, the current exceeds a first overcurrent protection threshold or the temperature exceeds a first temperature protection threshold, the control unit 100 controls the charging MOS transistor Q1 to be turned off;

if the voltage, current and temperature of the battery are recovered to normal values, the control unit 100 controls the charging MOS transistor Q1 to recover conduction;

the secondary protection module monitors the voltage of each battery cell, and if the voltage of a certain battery cell exceeds a second overvoltage protection threshold (the second overvoltage protection threshold can be larger than the first overvoltage protection threshold), the corresponding secondary protection module outputs a control signal to fuse the three-terminal fuse 300;

when the battery BAT needs to discharge, the pre-discharge MOS transistor Q4 is controlled to be turned on first, and after a set condition is reached, the pre-discharge MOS transistor Q4 is controlled to turn off the discharge MOS transistor Q2 to be turned on (a discharge current is discharged outwards through a diode in the MOS transistor Q1 and the MOS transistor Q2);

the control unit 100 monitors the voltage, the current and the temperature of the battery BAT, and if the voltage is lower than a first undervoltage protection threshold, the current exceeds a first overcurrent protection threshold or the temperature exceeds a first temperature protection threshold, the control unit 100 controls the discharge MOS transistor Q2 to be turned off;

if the battery voltage, current and temperature are restored to normal values, the control unit 100 controls the discharge MOS transistor Q2 to restore conduction.

Illustratively, in the practical application process, peripheral circuits of BQ76952 and SH367215 are set according to requirements.

Fig. 3 is a schematic diagram of a voltage acquisition function circuit in an embodiment, fig. 9 is a diagram of a BQ76952 pin in the embodiment, referring to fig. 3 and fig. 9, ends B1 to B14 and an end B16 serve as voltage sampling ends, one sides of ends B1 to B14 and an end B16 are connected to anodes of respective battery cells, the other sides of ends B1 to B14 and an end B16 are connected to VC1 to VC14 and VC16 pins of the BQ76952 through filter resistors and filter capacitors, one side of an end B0 is connected to a cathode of one battery cell, and the other side of an end B0 is connected to a VC0 pin of the BQ 76952.

Referring to fig. 3, a resistor R17 to a resistor R2 serve as a filter resistor, a capacitor C16 to a capacitor C1 serve as a filter capacitor, and a voltage sampling terminal is connected to a voltage sampling pin of the BQ76952 through a filter resistor and a filter capacitor. For example, the terminal B16 is connected to the pin VC16 of BQ76952 through a resistor R17 and a capacitor C16.

In the scheme, for example, the VC16 pin of the BQ76952 is in short circuit with the VC15 pin, and the capacitor C15 is configured to be a 0-ohm capacitor, so that the BQ76952 is suitable for voltage collection of 15 strings of batteries.

Referring to fig. 3, the peripheral circuit of BQ76952 further includes a diode D1, a resistor R18, a capacitor C18, a capacitor C21, a capacitor C22, a capacitor C1, and a capacitor C17, which are conventional in the arrangement of BQ76952, and the connection manner and function of each device are not elaborated.

Fig. 4 is a schematic diagram of a current collection function circuit in the embodiment, and referring to fig. 4 and fig. 9, the peripheral circuit of the BQ76952 further includes a resistor RS4, a resistor RS3, a resistor RS2, a resistor RS1, a resistor R19, a resistor R20, a capacitor C19, and a capacitor C20.

The resistor RS4, the resistor RS3, the resistor RS2 and the resistor RS1 are connected in parallel and then are connected in series in the charge-discharge circuit to serve as a current detection resistor. The resistor R19 and the resistor R20 are used as filter resistors, the capacitor C19 and the capacitor C20 are used as filter capacitors, one end of the current detection resistor is connected with the SRP pin of the BQ76952 through the resistor R19 and the capacitor C19, and the other end of the current detection resistor is connected with the SRN pin of the BQ76952 through the resistor R20 and the capacitor C20.

Fig. 5 is a schematic diagram of an auxiliary function circuit in an embodiment, and referring to fig. 5, the peripheral circuit of BQ76952 further includes a resistor R29; resistor R35, resistor R34, resistor R41, resistor R42, diode ZD3 and interface J2; resistance R27, resistance R26, resistance R30, resistance R28, electric capacity C26.

Referring to fig. 5, the interface J2 serves as a burning interface, the rest devices in fig. 5 are in the conventional arrangement of BQ76952, and the connection mode and function of each device are not described in detail.

Fig. 6 is a schematic diagram of a charge and discharge function circuit in an embodiment, referring to fig. 6, a MOS transistor Q7 is used as a precharge MOS transistor, and a precharge control terminal PCHG of BQ76952 is connected to a control terminal of a MOS transistor Q7 through a resistor R36. The resistor RS8, the resistor RS7 and the resistor RS5 are connected in parallel and then are connected in series with the drain electrode of the MOS transistor Q7, and the resistor RS8, the resistor RS7 and the resistor RS5 are used as current-limiting resistors of the MOS transistor Q7;

the MOS tube Q9 is used as a pre-discharge MOS tube, and the pre-discharge control end PDSG of the BQ76952 is connected with the control end of the MOS tube Q9 through a resistor R47. The resistor RS11, the resistor RS10 and the resistor RS9 are connected in parallel and then are connected in series with the drain of the MOS transistor Q9, and the resistor RS11, the resistor RS10 and the resistor RS9 are used as the current-limiting resistor of the MOS transistor Q9.

Referring to fig. 6 and 9, a MOS transistor Q4, a MOS transistor Q3, a MOS transistor Q6, and a MOS transistor Q5 are used as charging MOS transistors, a MOS transistor Q4, a MOS transistor Q3, a MOS transistor Q6, and a MOS transistor Q5 are connected in parallel and then connected in series in a charging and discharging loop, a charging control terminal CHG of the BQ76952 is connected with a control terminal of the MOS transistor Q5 through a resistor R37 after passing through a resistor R32 and a diode D3, is connected with a control terminal of the MOS transistor Q6 through a resistor R38, is connected with a control terminal of the MOS transistor Q3 through a resistor R39, and is connected with a control terminal of the MOS transistor Q4 through a resistor R40. The diode D3 is used for ensuring the unidirectional transmission of the charging control signal, and the resistor R37-resistor R40 are used as driving resistors;

referring to fig. 6, the source of the charging MOS transistor is further configured with a zener diode ZD2, and the zener diode ZD2 is used for voltage stabilization to prevent breakdown of the gate and source of the charging MOS transistor by high voltage.

Referring to fig. 6, a transistor Q2, a resistor R31, and a resistor R33 are also provided. The collector of the triode Q2 is connected with the charge-discharge loop through a resistor R31, the base of the triode Q2 is connected with the charging control end CHG of the BQ76952, and the emitter of the triode Q2 is connected with the source of the charging MOS tube through a resistor R33;

illustratively, when the charging MOS transistor is turned off, the transistor Q2 is turned on, and the charging MOS transistor discharges rapidly through the resistor R33 and the resistor R31.

Referring to fig. 6 and 9, a MOS transistor Q13, a MOS transistor Q12, a MOS transistor Q11, and a MOS transistor Q10 are used as discharge MOS transistors, a MOS transistor Q13, a MOS transistor Q12, a MOS transistor Q11, and a MOS transistor Q10 are connected in parallel and then connected in series in a charge-discharge loop, a discharge control terminal DSG of BQ76952 is connected to a control terminal of a MOS transistor Q10 through a resistor R43 after passing through a resistor R50, a resistor R51, and a diode D7, is connected to a control terminal of a MOS transistor Q11 through a resistor R44, is connected to a control terminal of a MOS transistor Q12 through a resistor R45, and is connected to a control terminal of a MOS transistor Q13 through a resistor R46;

referring to fig. 6, a zener diode ZD4 is disposed at the source of the discharge MOS transistor.

Referring to fig. 6, a transistor Q14, a diode D6, a resistor R48, a resistor R52, and a resistor R49 are also provided.

The discharge control end DSG of the BQ76952 is connected with the base electrode of a triode Q14 through a diode D6 and a resistor R48, the emitter electrode of the triode Q14 is connected with the source electrode of a discharge MOS tube through a resistor R49, and the collector electrode of the triode Q14 is connected with a charge-discharge loop through the resistor R52.

Illustratively, when the discharge MOS transistor is turned off, the transistor Q14 is turned on, and the discharge MOS transistor discharges rapidly through the resistor R49 and the resistor R52.

Referring to fig. 5 and 6, the drain of the charging MOS transistor, the drain of the discharging MOS transistor, and the source of the pre-charging MOS transistor and the pre-discharging MOS transistor are further connected to the collector of a transistor Q8 through a diode D4 and a resistor RS6, the base of the transistor Q8 is connected to the BERG end of BQ7695, and the emitter of the transistor Q8 is grounded through a capacitor C28; one end of the capacitor C30 is connected to the collector of the transistor Q8, and the other end is grounded.

Diode D4, resistance RS6, triode Q8, capacitor C28, and capacitor C30 are conventional arrangements of BQ76952, and the functions of each device will not be elaborated.

Referring to fig. 6, a capacitor C27, a capacitor C29, a resistor R53, a zener diode ZD5, a resistor R54, a diode D8, a MOS transistor Q15, a resistor R56, a resistor R55, a diode D9, a resistor R58, a resistor R57, a diode D10, a capacitor C32, a capacitor C31, and a diode TVS1 are further configured. The devices belong to the conventional arrangement of BQ76952, and the connection mode and functions of the devices are not explained in detail.

Referring to fig. 6, a diode D5 is further provided, the anode of the diode D5 is grounded, the cathode of the diode D5 is connected to the discharge control terminal DSG of the BQ76952, and the diode D5 is used to ensure that the discharge control terminal DSG is at a normal operating potential when the P + and P-terminals are reversely connected.

Fig. 7 is a schematic diagram of a fuse function circuit in the embodiment, referring to fig. 7, in the present embodiment, two three-terminal fuses F1 and F2 are used, and the three-terminal fuse F1 and the three-terminal fuse F2 are connected in parallel and then connected in series in a charge-discharge loop. One end of the three-terminal fuse is connected with the anode B + of the battery, and the other end of the three-terminal fuse is connected with the source electrode of the charging MOS tube;

referring to fig. 7 and 8, the output end of each secondary protection module is connected to the gate of the MOS transistor Q1 through the FUSE end, the drain of the MOS transistor Q1 is connected to the control ends of the three-terminal FUSE F1 and the three-terminal FUSE F2, and the source of the MOS transistor Q1 is grounded;

referring to fig. 7, a zener diode ZD1, a resistor R23 and a capacitor C24 are further connected in parallel between the gate and the source of the MOS transistor Q1, the zener diode ZD1 is used for stabilizing voltage, and the resistor R23 and the capacitor C24 are used for improving the on-off performance of the MOS transistor Q1;

referring to fig. 7, the battery further includes a light emitting diode D2, the positive electrode B + of the battery is connected to the drain of the MOS transistor Q1 through the light emitting diode D2, the resistor R25, and the resistor R24, the light emitting diode D2 is used to indicate whether the three-terminal fuse is blown, and the resistor R25 and the resistor R24 are used as current limiting resistors.

Fig. 8 is a schematic diagram of a secondary protection function circuit in an embodiment, referring to fig. 8, in this scheme, three secondary protection modules U2 to U4 are used, one secondary protection module is configured to acquire voltages of 5 battery cells, each secondary protection module is respectively and correspondingly configured with a plurality of filter resistors (R76 to R71, or R70 to R65, or R64 to R59), a plurality of filter capacitors (C44 to C41, C47, or C40 to C37, C45, or C36 to C33, or C46), and a triode (Q18, which simultaneously includes resistors R79, R82, and diode D13 or Q17, and simultaneously includes resistors R78, R81, diode D12, or Q16, and simultaneously includes resistors R77, R80, and diode D11).

Fig. 10 is a diagram of SH367215 pins in an embodiment, and referring to fig. 8 and 10, the peripheral circuits of each secondary protection module are configured in the same manner, taking a secondary protection module U3 as an example, one end of each of B6 to B10 is connected to the positive electrode of a corresponding battery cell, and the other end of each of B6 to B10 is connected to VC5 to VC1 pins of SH367215 through a filter resistor and a filter capacitor;

the positive electrode (B10) of the 10 th cell in series is connected with the VDD pin of SH367215, and the positive electrode (B5) of the 5 th cell in series is connected with the GND pin of SH 367215;

the OUT pin of SH367215 is connected with the emitter of a triode Q17, the anode (B5) of the 5 th electric core in series is connected with the base of a triode Q17 through a resistor R78, and the collector of a triode Q17 is connected with the FUSE end through a resistor R81 and a diode D12.

The secondary protection module monitors the voltage of each battery cell, if the voltage of a certain battery cell exceeds a second overvoltage protection threshold value, the output end (OUT end) of the corresponding secondary protection module outputs a control signal, so that the corresponding triode is conducted, the triode drives the MOS tube Q1 to be conducted, and then the three-terminal fuse F1 and the three-terminal fuse F2 are fused.

Referring to fig. 8, in the present solution, the process of acquiring the cell voltage and outputting the control signal by one secondary protection module does not depend on other secondary protection modules, and secondary protection for the whole charging and discharging circuit can be effectively implemented.

EXAMPLE III

The embodiment provides a power supply, which includes a battery and a charging and discharging circuit, wherein the charging and discharging circuit is used for charging and discharging control of the battery and charging and discharging protection in a charging and discharging process.

The charge/discharge circuit may be any one of the charge/discharge circuits described in the first and second embodiments.

Example four

The present embodiment provides an electric vehicle equipped with the power supply of the third embodiment.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the utility model. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A charge and discharge circuit is characterized by comprising a control unit, a secondary protection unit and a three-terminal fuse;

the secondary protection unit is provided with a second voltage sampling end and a protection control end, and the three-end fuse is connected in a charge-discharge loop in series;

the first voltage sampling end is used for collecting the voltage of a battery, the charging control end is connected with the control end of a charging MOS (metal oxide semiconductor) tube connected in series in a charging and discharging loop, and the discharging control end is connected with the control end of a discharging MOS tube connected in series in the charging and discharging loop;

the control unit is used for adjusting the on-off state of the charge and discharge MOS tube according to the sampling value of the first voltage sampling end;

the secondary protection unit is used for outputting a signal for controlling the fusing of the three-terminal fuse through the protection control end according to a sampling value of the second voltage sampling end;

the charging circuit further comprises a triode Q2, a resistor R31 and a resistor R33, wherein a collector of the triode Q2 is connected with the charging and discharging loop through a resistor R31, a base of the triode Q2 is connected with the charging control end, and an emitter of the triode Q2 is connected with a source of the charging MOS tube through a resistor R33;

the discharging control circuit further comprises a triode Q14, a diode D6, a resistor R48, a resistor R52 and a resistor R49, the discharging control end is connected with the base electrode of the triode Q14 through the diode D6 and the resistor R48, the emitter electrode of the triode Q14 is connected with the source electrode of the discharging MOS tube through the resistor R49, and the collector electrode of the triode Q14 is connected with the charging and discharging loop through the resistor R52.

2. The charge and discharge circuit according to claim 1, wherein the secondary protection unit comprises a plurality of secondary protection modules;

3. The charging and discharging circuit of claim 2, wherein one of the secondary protection modules is powered by one of the cells connected thereto.

4. The charge and discharge circuit according to claim 1, further comprising a current detection resistor, wherein the control unit is further provided with a current detection terminal;

the current detection resistor is connected in series in the charge-discharge loop, and the control unit is connected with the current detection resistor through the current detection end.

5. The charge and discharge circuit according to claim 1, further comprising a temperature sensor, wherein the control unit is further provided with a temperature detection terminal;

6. The charging and discharging circuit according to claim 1, wherein the control unit is further configured with a pre-charge and discharge control terminal;

7. The charging and discharging circuit according to claim 1, wherein the control unit is of type BQ76952, and the secondary protection module is of type SH 367215.

8. A power supply comprising a battery, the charging and discharging circuit of any one of claims 1 to 7;

the charge and discharge circuit is used for charge and discharge control of the battery and charge and discharge protection in the charge and discharge process.

9. An electric vehicle equipped with the power supply according to claim 8.