CN115241950A

CN115241950A - Lithium battery management circuit based on MCU

Info

Publication number: CN115241950A
Application number: CN202210931740.1A
Authority: CN
Inventors: 杨明军; 郭海清; 蒋常杰
Original assignee: Ningbo Quanyi Electronic Technology Co ltd
Current assignee: Ningbo Quanyi Electronic Technology Co ltd
Priority date: 2022-08-04
Filing date: 2022-08-04
Publication date: 2022-10-25

Abstract

The application discloses lithium battery management circuit based on MCU includes: the MCU master control circuit comprises a master control chip and a peripheral circuit thereof; the ID resistor identification circuit is connected with the main control chip and used for detecting the resistance value of the ID resistor during the discharge of the lithium battery; the charging voltage electric measuring circuit is connected with the main control chip and is used for detecting a charging voltage value when the lithium battery is charged; the discharge control circuit is connected with the main control chip and controls the on/off of the discharge circuit; and the discharge current detection circuit is connected with the main control chip and the discharge control circuit and is used for collecting the current value passing through the load when the lithium battery discharges. The single MCU is adopted to realize the charge and discharge control of the lithium battery, so that an analog front end module is omitted, and the circuit cost is reduced.

Description

Lithium battery management circuit based on MCU

Technical Field

The application relates to a lithium battery management circuit, in particular to a lithium battery management circuit based on an MCU.

Background

Lithium batteries have the advantages of light weight, high energy density, small size, low self-leakage current, etc., and are increasingly used in electric tools. Batteries of low-voltage electric tools such as electric wrenches, electric screwdrivers, dust collectors, electric shears and the like on the market are mostly lithium batteries. A commonly used lithium battery pack is composed of a plurality of battery cells or single batteries connected in series. Generally, S represents the core number of the battery pack or the parallel number of the single batteries; for example, a common electric tool is 5S1P, which is formed by connecting 5 single lithium batteries in series.

In order to ensure the safe and reliable operation of the battery, the battery management system needs to have the functions of battery state monitoring and evaluation, charge and discharge control, battery equalization and the like: and (3) monitoring and acquiring state parameters (including but not limited to single battery voltage, battery pole temperature, battery loop current, battery pack terminal voltage, battery system insulation resistance and the like) of the battery in real time. When detecting the battery state (voltage and temperature), we need to use BMS AFE (battery management system analog front end chip), which is a monitoring chip of multi-sampling channel, and can monitor the cell voltage and temperature of the cells connected in series.

For example, the chinese patent application "a multi-cell series lithium battery pack equalization and protection system"; the application numbers are: cn201110242697.X; the method comprises the following steps: the lithium battery charging and discharging assembly is used for connecting an external charging power supply into the lithium battery pack for charging and supplying power to a load; the control module is communicated with the lithium battery charging and discharging assembly in an IIC mode to control the lithium battery charging and discharging assembly to be fully charged; the lithium battery charging and discharging assembly includes: the analog front-end circuit is used for acquiring voltage data of each lithium battery in the lithium battery pack and sending the acquired voltage data to the control module through the IIC bus so that the control module can generate a plurality of equalizing charge control signals for equalizing charge of each lithium battery; the equalizing driving circuit is used for generating a plurality of equalizing driving signals according to the equalizing charging control signals; and the equalizing circuit is used for controlling each lithium battery to be fully charged according to the plurality of equalizing driving signals.

The lithium battery is controlled and managed by adopting the analog front-end module, and the lithium battery management system has the advantages of simple control circuit and easiness in implementation. However, there are some disadvantages: the discharging circuit can not be designed differently, and the charging control loop can only be controlled by a single loop.

Disclosure of Invention

The technical problem that this application will be solved provides a lithium cell management circuit based on MCU, adopts single MCU to realize the charge-discharge control of lithium cell, has saved simulation front end module, reduces the circuit cost to realize the individualized design of product function.

The technical scheme adopted by the application is as follows: lithium battery management circuit based on MCU includes:

the MCU master control circuit comprises a master control chip and a peripheral circuit thereof;

the ID resistor identification circuit is connected with the main control chip and used for detecting the resistance value of the ID resistor during the discharge of the lithium battery;

the charging voltage electric measuring circuit is connected with the main control chip and is used for detecting a charging voltage value when the lithium battery is charged;

the discharge control circuit is connected with the main control chip and controls the on/off of the discharge circuit;

and the discharge current detection circuit is connected with the main control chip and the discharge control circuit and is used for collecting the current value passing through the load when the lithium battery discharges.

Compared with the prior art, the application has the advantages that: in the technical scheme of this application, saved simulation front end module, only set up single chip promptly main control chip in MCU main control circuit, realized the charge-discharge control of lithium cell, reduced the cost of lithium cell control on the circuit by a wide margin. An ID resistance identification circuit is additionally arranged, and the ID resistance is used for adapting to the output capability of different electric equipment. The ID resistor identification circuit can detect the resistance value of the ID resistor, can adapt to different electric equipment, and achieves differentiation protection.

In the present application, the circuit composition of each part is mainly distinguished by the functions realized by each part of the circuit, but in an actual circuit, the circuit and the circuit are mixed together and cannot be completely distinguished.

In some embodiments of the present application, the main control chip is a chip with a model number FT62F 286A. Specific pin descriptions of the main control chip are given in the drawings of the specification and are not described herein again.

In some embodiments of the present application, the ID resistance recognition circuit includes a charging input positive terminal, a discharging output negative terminal, a fifth diode and a seventh diode, the positive terminal of the fifth diode is connected to the main control chip through a sixteenth resistor, the positive terminal of the seventh diode is connected to the negative terminal of the fifth diode, and a matching resistor is connected between the negative terminal of the seventh diode and the charging input negative terminal.

Specifically, the matching resistor may be a null resistor, or a resistor of 10k Ω, or a resistor of 15k Ω, or a resistor of 22k Ω, or a resistor of 33k Ω. And (4) if the matching resistor is empty, namely, the resistor is not installed at the position, and the empty processing is carried out.

Specifically, the negative electrode end of the seventh diode is grounded through the eighth capacitor, the twenty-second resistor and the twenty-seventh resistor

Specifically, the ID resistance identification circuit is connected to a P _ ID pin of the main control chip. That is, the sixteenth resistor is connected to the P _ ID pin of the main control chip.

In some embodiments of the present application, the charging voltage measuring circuit includes a tenth capacitor and a twenty-fifth resistor; the tenth capacitor is connected with the twenty-fifth resistor in parallel, one end of the twenty-fifth resistor is connected with the main control chip, and the other end of the twenty-fifth resistor is grounded.

And one end of the twenty-fifth resistor is connected with the cathode of the fifth diode through the nineteenth resistor.

Specifically, the charging voltage electrical measurement circuit is connected with a CHS _ IDV pin of the main control chip. Namely, one end of the twenty-fifth resistor is connected with the CHS _ IDV pin of the main control chip.

In the application, the ID resistance identification circuit and the charging voltage detection circuit are combined, so that the purposes of simplifying the circuit and simplifying the wiring of a peripheral circuit are achieved. The principle of combining the two circuits is as follows: the ID resistor is only needed when the lithium battery discharges, and the positive terminal of the charging input is only needed when the lithium battery charges, so that the ID resistor and the positive terminal are combined with each other, and the practical application of functions is not influenced.

The specific circuit is as follows: when the output of the P _ ID pin of the main control chip is high level and no charger is inserted, the voltage of the positive terminal of the charging input in the ID resistance identification circuit is directly controlled by the main control chip.

When the ID resistor is connected to the charging input positive terminal and the discharging output negative terminal, the CHS _ IDV pin of the main control chip can detect the resistance value of the ID resistor, so that the detection function of the ID resistor in the application is realized.

When the output of the P _ ID pin of the main control chip is low level, the CHS _ IDV pin of the main control chip directly reflects the input voltage of the DC charger, so that the charging voltage detection function is realized, and correct collection of the charging voltage cannot be influenced no matter whether an ID resistor is connected or not.

In the present application, the ID resistors are integrated into the terminals of the power tool, and different power tools are distinguished by different ID resistors to realize different protection currents. Therefore, the matching problem of the battery pack can be solved by identifying the resistors through different IDs.

In some embodiments of the present application, the discharge control circuit includes an eleventh triode, a twelfth triode, and a fet group, wherein a collector of the twelfth triode is connected to the controllable power supply, and a base of the twelfth triode is connected to the main control chip through a twenty-four resistor.

And the base electrode of the eleventh triode is connected with the collector electrode of the twelfth triode, the emitter electrode of the eleventh triode is connected with the emitter electrode of the twelfth triode, and the collector electrode of the eleventh triode is connected with the controllable power supply.

The collector electrode of the eleventh triode is connected with the grid electrode of the field effect tube group, the emitter electrode of the eleventh triode is connected with the source electrode of the field effect tube group, the grid electrode of the field effect tube group is connected with the discharge output cathode end, and the grid electrode of the field effect tube group is connected with the positive electrode end of the battery through the positive electrode of the fast recovery diode.

Specifically, the discharge control circuit is connected with a DSG pin of the main control chip. Namely, the twenty-fourth resistor is connected with the DSG pin of the main control chip.

In some embodiments of the present application, the discharge current detection circuit includes a twenty-third resistor, a twenty-eighth resistor and a ninth capacitor, one end of the ninth capacitor is grounded, the other end of the ninth capacitor is connected to the CIS pin of the main control chip, the CIS pin of the main control chip is connected to one end of the twenty-third resistor, the other end of the twenty-third resistor is connected to the P _ CIS pin of the main control chip, the CIS pin of the main control chip is connected to one end of the twenty-ninth resistor, and the other end of the twenty-ninth resistor is connected to the emitter of the eleventh triode.

In some embodiments of the present application, the discharge control circuit is connected to the ID resistor identification circuit through a degeneration resistor set. Specifically, a negative feedback resistor group is connected between the other end of the twenty-fifth resistor and an emitting electrode of the eleventh triode.

In the present application, the discharge current detection circuit is combined with a discharge control circuit, wherein a DSG pin of the main control chip is used for controlling the discharge control circuit. When the DSG pin of the main control chip outputs high level, the field effect tube group is in a conducting state. The lithium cell this moment lithium cell discharge backward flow does this moment: the device comprises a battery positive terminal, a discharge output positive terminal, a motor, a discharge output negative terminal, a field effect tube group, a negative feedback resistor group and a battery negative terminal.

When the DSG pin of the main control chip outputs a low level, the discharging negative loop of the lithium battery is in a disconnected state, so that the on-off of the discharging control circuit is controlled.

When the P _ CIS pin of the main control chip is at a low level, the CIS pin of the main control chip is used for collecting the current of the load of the lithium battery during discharging.

When the P _ CIS pin of the main control chip is at a high level, the CIS pin of the main control chip generates an offset voltage, which is about 0.455V in the embodiment of the present application. Considering that when the lithium battery is in a charging state, the current direction is from the battery cathode end to the battery anode end, at this moment, the CIS generates a negative signal smaller than 0, and the MCU cannot acquire the signal, so that the negative signal can be effectively detected by introducing an offset voltage.

In the present application, when the P _ CIS pin is at a low level, the detected current value is the charging current value, which constitutes the charging current detection circuit in the present application.

In some embodiments of the present application, the present application further includes a charge and discharge loop wake-up circuit.

Specifically, the discharge loop Wake-up circuit comprises a tenth field effect transistor, a drain of the tenth field effect transistor is connected with a Wake pin of the main control chip, a source of the tenth field effect transistor is grounded, and a gate of the tenth field effect transistor is connected with a discharge output negative electrode end through a twenty-first resistor and a seventh capacitor. For discharge wake-up.

Specifically, the charging loop wake-up circuit includes a seventh diode, an eighth capacitor, a twenty-second resistor, a twenty-seventh resistor and a tenth field effect transistor, and is used for realizing the wake-up by inserting the charger.

In this embodiment, the negative terminal of the discharge output is in an off state from the ground GND. When a load is connected between the discharge output positive terminal and the discharge output negative terminal, the discharge output positive terminal and the discharge output negative terminal are in an equipotential state. Therefore, the negative terminal of the discharge output can drive the tenth field effect transistor through the seventh capacitor to change the Wake pin of the main control chip from high level to low level. Thereby realizing the awakening function of the main control chip.

And the grid electrode of the tenth field effect transistor is connected with the cathode end of the seventh diode through the twelfth resistor and the eighth capacitor. Namely, when the positive terminal of the charging input is accessed by a DC charger, the tenth field effect transistor can be driven by the eighth capacitor to change the Wake pin of the main control chip from high level to low level. Thereby realizing the awakening function of the main control chip.

In some embodiments of the present application, the present application further includes a charge control circuit, the charge control circuit includes a sixth field effect transistor and a third field effect transistor, a gate of the sixth field effect transistor is connected to the CH1 pin of the main control chip, a source of the sixth field effect transistor is grounded, a drain of the sixth field effect transistor is connected to the gate of the third field effect transistor, and the source of the third field effect transistor is connected to the positive terminal of the battery through a diode group.

The charging control circuit further comprises a ninth field effect tube and a seventh field effect tube, wherein the grid electrode of the ninth field effect tube is connected with the CH2 pin of the main control chip, the source electrode of the ninth field effect tube is grounded, the drain electrode of the ninth field effect tube is connected with the grid electrode of the seventh field effect tube, the source electrode of the seventh field effect tube is connected with the drain electrode of the third field effect tube, and the drain electrode of the seventh field effect tube is connected with the positive terminal of the charging input.

In this embodiment, when the CH2 pin of the main control chip is at a high level, the ninth fet is in a conducting state, and at this time, a voltage drop is generated between the gate of the seventh fet and the positive terminal of the charging input, so that the seventh fet is in a conducting state; when the CH2 pin of the main control chip is at a low level, the seventh field effect transistor is in a disconnected state.

The circuit principle at the CH1 pin of the main control chip is the same as described above.

When the CH1 pin and the CH2 pin of the main control chip are both at a high level, the charging voltage loop is: the negative feedback resistor group comprises a charging input positive terminal, a seventh field effect transistor, a third field effect transistor, a secondary tube group, a battery positive terminal, a battery negative terminal, a negative feedback resistor group, a field effect tube group and a discharging output negative terminal.

In some embodiments of the present application, the present application further includes a controllable power supply control circuit connected to the main control chip, the controllable power supply control circuit is connected to the positive terminal of the battery, and the controllable power supply control circuit outputs a controllable power supply.

The first control power supply control circuit can provide voltage for driving the field effect transistor. Secondly, the power consumption is reduced in the sleep mode. When the MOS _ GATE pin of the main control chip is at a high level, the controllable power supply VCC is about 15V. When the MOS _ GATE pin of the main control chip is at a low level, the controllable power supply VCC is 0V.

In some embodiments of the present application, the present application further includes a battery voltage detection circuit, where the battery voltage detection circuit is configured to detect a battery voltage of each lithium battery, and the battery voltage detection circuit is connected to the main control chip.

The battery voltage detection circuit is connected with a controllable power supply, and the controllable power supply supplies power to the battery voltage detection circuit. The controllable power source VCC is used for controlling the on-off of the battery voltage detection circuit.

The battery voltage detection circuit comprises a sampling resistor, and the sampling resistor is connected with the lithium battery. The sampling resistor requires a precision resistor of 1%.

When the controllable power supply VCC is at a high level, the battery voltage detection circuit is in a conducting state, and the battery voltage can be collected through the main control chip at the moment. When the controllable power supply VCC is at a low level, the battery voltage detection loop is in a disconnected state, and the self-consumption of the battery can be effectively reduced.

In some embodiments of the present application, the present application further comprises a battery temperature detection circuit, the battery temperature detection circuit comprising a thermistor, the thermistor being bonded together with the lithium battery through the thermally conductive silicone. The circuit is used for monitoring the battery temperature of the lithium battery in the charging and discharging process. When the temperature exceeds the design range of charge and discharge, the purpose of managing charge and discharge is achieved.

In some embodiments of the present application, the present application further comprises a key and an LED control circuit. The key is used for awakening the main control chip and indicating the electric quantity of the battery when the main control chip is in a dormant state. The LED is used for indicating the residual capacity in the discharging process; and also for indicating the amount of remaining charge during charging.

In some embodiments of the present application, the present application further includes a DC charger input detection circuit, the DC charger input detection circuit includes a charging connector, and the DC charger input detection circuit is connected to the main control chip. The DC charger input detection circuit is for detecting a charger insertion detection. The DC charging loop has no charging current detection function.

In some embodiments of the present application, the present application further includes a communication control circuit, and the communication control circuit connects the main control chip and the external output connector. This application can pass through communication control circuit and give the charger with information such as temperature, voltage through the mode of communication. And preconditions are made for the subsequent intelligent quick charging technology.

In some embodiments of the present application, the present application further comprises a power supply circuit outputting a power supply voltage of 5V. The power supply circuit supplies power for the MCU master control circuit and other circuits in the application.

The above embodiments may be combined arbitrarily, in accordance with common general knowledge in the art.

Drawings

The present application will be described in further detail below with reference to the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of illustrating the preferred embodiments and therefore should not be taken as limiting the scope of the present application. Furthermore, unless specifically stated otherwise, the drawings are merely schematic representations based on conceptual representations of elements or structures depicted and may contain exaggerated displays and are not necessarily drawn to scale.

FIG. 1 is a functional block diagram of the present application;

FIG. 2 is an MCU master control circuit of the present application;

fig. 3 is a charging control circuit and a power supply circuit of the present application;

FIG. 4 is a controllable power supply control circuit of the present application;

FIG. 5 is a DC charger input detection circuit of the present application;

fig. 6 shows a discharge control circuit, a discharge current detection circuit, a charge/discharge wake-up circuit, an ID identification circuit, and a charge voltage detection circuit according to the present application;

FIG. 7 is a battery voltage detection circuit of the present application;

FIG. 8 is a battery temperature detection circuit of the present application;

FIG. 9 is a communication control circuit of the present application;

fig. 10 is a key and LED control circuit of the present application.

Wherein the reference numerals are specified as follows: u2, a main control chip; ID1, ID resistance; c +, charging input positive terminal; b +, the positive terminal of the battery; b-, the negative terminal of the battery; p +, positive terminal of discharge output; p-, a discharge output negative terminal; DC1, a charging connector; VCC, a controllable power supply; VDD, supply voltage;

d5, a fifth diode; d7, a seventh diode;

r16, sixteenth resistor; r19, nineteenth resistor; r21 and a twenty-first resistor; r22 and a twenty-second resistor; r23, a twenty-third resistor; r24, a twenty-fourth resistor; r25, a twenty-fifth resistor; r27 and a twenty-seventh resistor; r28, twenty-eighth resistor; r29 and a twenty-ninth resistor; RT1, a thermistor;

c7, a seventh capacitor; c8, an eighth capacitor; c9, ninth capacitor; c10, tenth capacitance;

q12 and a twelfth triode; q13 and an eleventh third-stage pipe;

q3, a third field effect transistor; q6, a sixth field effect tube; q7, a seventh field effect transistor; q9 and a ninth field effect transistor; q10 and a tenth field effect transistor.

Detailed Description

The present application will now be described in detail with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

A lithium battery management circuit based on MCU, as shown in fig. 1 to fig. 10: the charge and discharge control of the lithium battery is realized by adopting a single MCU, an analog front-end module is omitted, and the circuit cost is reduced.

the MCU master control circuit comprises a master control chip U2 and peripheral circuits thereof;

the ID resistor identification circuit is connected with the main control chip U2 and used for detecting the resistance value of the ID resistor during discharging of the lithium battery;

the charging voltage electric measuring circuit is connected with the main control chip U2 and is used for detecting a charging voltage value when the lithium battery is charged;

the discharge control circuit is connected with the main control chip U2 and controls the on/off of the discharge circuit;

and the discharge current detection circuit is connected with the main control chip U2 and the discharge control circuit and is used for collecting the current value of the lithium battery passing through the load during discharge.

In the technical scheme of this application, saved simulation front end module, only set up single chip in MCU master control circuit and be main control chip U2, realized the charge and discharge control of lithium cell, reduced the cost of lithium cell control on the circuit by a wide margin. An ID resistor identification circuit is additionally arranged, and the ID resistor is used for preventing the battery from being burnt due to overlarge instantaneous discharge current. The ID resistor identification circuit can detect the resistance of the ID resistor, can adapt to different lithium batteries, and achieves differentiation protection.

The main control chip U2 adopts a chip with the model number FT62F 286A. Specific pin descriptions of the main control chip U2 are given in the drawings of the specification, and are not described herein again.

The ID resistance identification circuit comprises a charging input positive end C +, a discharging output negative end P, a fifth diode D5 and a seventh diode D7, wherein the positive end of the fifth diode D5 is connected with the main control chip U2 through a sixteenth resistor R16, the positive end of the seventh diode D7 is connected with the negative end of the fifth diode D5, and a matching resistor ID1 is connected between the negative end of the seventh diode D7 and the charging input negative end.

Specifically, the matching resistor ID1 may be null, or a resistor of 10k Ω, or a resistor of 15k Ω, or a resistor of 22k Ω, or a resistor of 33k Ω. And (4) leaving the empty processing when the matching resistor ID1 is empty, namely, the resistor is not installed here.

Specifically, the negative terminal of the seventh diode D7 is grounded through an eighth capacitor C8, a twenty-second resistor R22 and a twenty-seventh resistor R27

Specifically, the ID resistor identification circuit is connected to a P _ ID pin of the main control chip U2. That is, the sixteenth resistor R16 is connected to the P _ ID pin of the main control chip U2.

The charging voltage electric measuring circuit comprises a tenth capacitor C10 and a twenty-fifth resistor R25; the tenth capacitor C10 is connected in parallel with the twenty-fifth resistor R25, one end of the twenty-fifth resistor R25 is connected with the main control chip U2, and the other end of the twenty-fifth resistor R25 is grounded.

One end of the twenty-fifth resistor R25 is connected to the cathode of the fifth diode D5 through a nineteenth resistor R19.

Specifically, the charging voltage measuring circuit is connected with a CHS _ IDV pin of the main control chip U2. That is, one end of the twenty-fifth resistor R25 is connected to the CHS _ IDV pin of the main control chip U2.

In the application, the ID resistance identification circuit and the charging voltage detection circuit are combined, so that the purposes of simplifying the circuit and simplifying the wiring of a peripheral circuit are achieved. The principle of combining the two circuits is as follows: the ID resistor is only needed when the lithium battery discharges, and the charging input positive terminal C + is only needed when the lithium battery charges, and the ID resistor and the charging input positive terminal C + are combined with each other, so that the practical application of functions is not influenced.

The specific circuit is as follows: when the output of the P _ ID pin of the main control chip U2 is high level and no charger is inserted, the voltage of the positive terminal C + of the charging input in the ID resistance identification circuit is directly controlled by the main control chip U2.

When the ID resistor is connected with the charging input positive terminal C + and the discharging output negative terminal, the CHS _ IDV pin of the main control chip U2 can detect the resistance value of the ID resistor, so that the detection function of the ID resistor in the application is realized.

When the output of the P _ ID pin of the main control chip U2 is a low level, the CHS _ IDV pin of the main control chip U2 directly reflects the input voltage of the DC charger, thereby realizing the detection function of the charging voltage, and the correct collection of the charging voltage is not affected no matter whether the ID resistor is connected.

The discharging control circuit comprises an eleventh triode Q13, a twelfth triode Q12 and a field effect tube group, wherein a collector of the twelfth triode Q12 is connected with a controllable power supply VCC, and a base of the twelfth triode Q12 is connected with the main control chip U2 through a twenty-four resistor R24. The field effect tube group is formed by connecting three field effect tubes Q13, Q23 and Q14 in parallel.

And the base electrode of the eleventh triode is connected with the collector electrode of the twelfth triode Q12, the emitter electrode of the eleventh triode is connected with the emitter electrode of the twelfth triode Q12, and the collector electrode of the eleventh triode is connected with the controllable power supply VCC.

The collector of the eleventh triode is connected with the grid of the field-effect tube group, the emitter of the eleventh triode is connected with the source of the field-effect tube group, the grid of the field-effect tube group is connected with the negative end of the discharge output, and the grid of the field-effect tube group is connected with the positive end B + of the battery through the positive electrode of the fast recovery diode.

Specifically, the discharge control circuit is connected with a DSG pin of the main control chip U2. Namely, the twenty-fourth resistor R24 is connected to the DSG pin of the main control chip U2.

The discharging current detection circuit comprises a twenty-third resistor R23, a twenty-eighth resistor R28 and a ninth capacitor C9, one end of the ninth capacitor C9 is grounded, the other end of the ninth capacitor C9 is connected with the CIS pin of the main control chip U2, the CIS pin of the main control chip U2 is connected with one end of the twenty-third resistor R23, the other end of the twenty-third resistor R23 is connected with the P _ CIS pin of the main control chip U2, the CIS pin of the main control chip U2 is connected with one end of the twenty-ninth resistor R29, and the other end of the twenty-ninth resistor R29 is connected with the emitting electrode of the eleventh triode.

The discharge control circuit is connected with the ID resistance identification circuit through a negative feedback resistance group. Specifically, a negative feedback resistor group is connected between the other end of the twenty-fifth resistor R25 and an emitter of the eleventh triode. The negative feedback resistor group is formed by connecting two resistors RS1 and RS2 in parallel.

In the present application, the discharge current detection circuit is combined with a discharge control circuit, wherein the DSG pin of the main control chip U2 is used for controlling the discharge control circuit. When the DSG pin of the main control chip U2 outputs a high level, the field effect tube group is in a conducting state. The lithium battery discharge backflow at this time is as follows: the device comprises a battery positive terminal B +, a discharge output positive terminal P +, a motor, a discharge output negative terminal P-, a field effect tube group, a negative feedback resistor group and a battery negative terminal B.

When the DSG pin of the main control chip U2 outputs a low level, the discharging negative loop of the lithium battery is in a disconnected state, so that the on-off of the discharging control circuit is controlled.

When the P _ CIS pin of the main control chip U2 is at a low level, the CIS pin of the main control chip U2 is used for collecting the current of the load of the lithium battery during discharging.

When the P _ CIS pin of the main control chip U2 is at a high level, the CIS pin of the main control chip U2 generates an offset voltage, which is about 0.455V in the embodiment of the present application. Considering that when the lithium battery is in a charging state, the current direction is from the battery cathode end to the battery anode end B +, and at this time, the CIS generates a negative signal smaller than 0, and the MCU cannot acquire the signal, so that the negative signal can be effectively detected by introducing an offset voltage.

The charge and discharge circuit awakening circuit comprises a discharge circuit awakening circuit and a charge circuit awakening circuit.

Specifically, the discharge loop Wake-up circuit includes a tenth field effect transistor Q10, a drain of the tenth field effect transistor Q10 is connected to a Wake pin of the main control chip U2, a source of the tenth field effect transistor Q10 is grounded, and a gate of the tenth field effect transistor Q10 is connected to a discharge output cathode end P-through a twenty-first resistor R21 and a seventh capacitor C7, so as to achieve discharge Wake-up.

Specifically, the charging loop wake-up circuit includes a seventh diode D7, an eighth capacitor C8, a twenty-second resistor R22, a twenty-seventh resistor R27, and a tenth fet Q10, and is configured to implement a charger plug-in wake-up.

In the present embodiment, the negative terminal of the discharge output is in an off state from the ground GND. When a load is connected between the discharge output positive terminal P + and the discharge output negative terminal, the discharge output positive terminal P + and the discharge output negative terminal are in an equipotential state. Therefore, the negative terminal of the discharge output can drive the tenth fet Q10 through the seventh capacitor C7 to change the Wake pin of the main control chip U2 from high level to low level. Thereby realizing the awakening function of the main control chip U2.

The grid electrode of the tenth field effect transistor Q10 is connected with the cathode end of the seventh diode D7 through the twelfth resistor R22 and the eighth capacitor C8. That is, when the positive terminal C + of the charging input is accessed by a DC charger, the tenth fet Q10 is driven by the eighth capacitor C8, so that the Wake pin of the main control chip U2 changes from high level to low level. Thereby realizing the awakening function of the main control chip U2.

This application still includes the control circuit that charges, the control circuit that charges include sixth field effect transistor Q6 and third field effect transistor Q3, sixth field effect transistor Q6's grid be connected with main control chip U2's CH1 pin, sixth field effect transistor Q6's source ground connection, sixth field effect transistor Q6's drain electrode is connected with third field effect transistor Q3's grid, third field effect transistor Q3's source pass through diode group and be connected with battery positive terminal B +. The diode group is formed by connecting two diodes D2 and D3 in parallel.

The charging control circuit further comprises a ninth field-effect tube Q9 and a seventh field-effect tube Q7, the grid electrode of the ninth field-effect tube Q9 is connected with the CH2 pin of the main control chip U2, the source electrode of the ninth field-effect tube Q9 is grounded, the drain electrode of the ninth field-effect tube Q9 is connected with the grid electrode of the seventh field-effect tube Q7, the source electrode of the seventh field-effect tube Q7 is connected with the drain electrode of the third field-effect tube Q3, and the drain electrode of the seventh field-effect tube Q7 is connected with the charging input positive electrode end C +.

In this embodiment, when the CH2 pin of the main control chip U2 is at a high level, the ninth fet Q9 is in a conducting state, and at this time, a voltage drop is generated between the gate of the seventh fet Q7 and the positive charging input terminal C +, so that the seventh fet Q7 is in a conducting state; when the CH2 pin of the main control chip U2 is at a low level, the seventh field effect transistor Q7 is in an off state.

The circuit principle at the CH1 pin of the main control chip U2 is the same as described above.

When the CH1 pin and the CH2 pin of the main control chip U2 are both at a high level, the charging voltage loop is: a charging input positive terminal C +, a seventh field effect transistor Q7, a third field effect transistor Q3, a secondary tube group, a battery positive terminal B +, a battery negative terminal B-, a negative feedback resistor group, a field effect tube group and a discharging output negative terminal P-.

This application still includes the controllable power VCC control circuit who is connected with main control chip U2, and controllable power VCC control circuit connects battery positive terminal B +, controllable power VCC control circuit exports controllable power VCC.

The first power control circuit can provide voltage for the field effect transistor drive. Secondly, the power consumption is reduced in the sleep mode. When the MOS _ GATE pin of the main control chip U2 is at a high level, the controllable power supply VCC is about 15V. When the MOS _ GATE pin of the main control chip U2 is low, the controllable power VCC is 0V.

This application still includes battery voltage detection circuitry, and battery voltage detection circuitry is used for detecting the battery voltage of every section lithium cell, and battery voltage detection circuitry is connected with main control chip U2.

The battery voltage detection circuit is connected with a controllable power supply VCC, and the controllable power supply VCC supplies power to the battery voltage detection circuit. The controllable power source VCC is used for controlling the on-off of the battery voltage detection circuit.

The battery voltage detection circuit comprises a sampling resistor, and the sampling resistor is connected with the lithium battery. The sampling resistor requires 1% precision resistor R33/R34/R35/R36/R37.

When the controllable power source VCC is at a high level, the battery voltage detection circuit is in a conducting state, and the battery voltage can be collected through the main control chip U2. When the controllable power supply VCC is at a low level, the battery voltage detection loop is in a disconnected state, and the self-consumption of the battery can be effectively reduced at the moment.

This application still includes battery temperature detection circuitry, and battery temperature detection circuitry includes thermistor RT1, and thermistor RT1 is in the same place through heat conduction silica gel and lithium cell bonding. The circuit is used for monitoring the battery temperature of the lithium battery in the charging and discharging processes. When the temperature exceeds the design range of charging and discharging, the purpose of managing charging and discharging is achieved.

The application also comprises a key and an LED control circuit. The key is used for waking up the main control chip U2 and indicating the function of the battery power when the main control chip is in a dormant state. The LED is used for indicating the residual capacity in the discharging process; and also for indicating the amount of remaining charge during charging.

The application further comprises a DC charger input detection circuit, wherein the DC charger input detection circuit comprises a charging connector DC1, and the DC charger input detection circuit is connected with the main control chip U2. The DC charger input detection circuit is used to detect charger insertion detection. The DC charging loop has no charging current detection function.

This application still includes communication control circuit, and communication control circuit connects main control chip U2 and outside output to connect. This application can pass through communication control circuit and give the charger with information such as temperature, voltage through the mode of communication. And preconditions are made for the subsequent intelligent quick charging technology.

The power supply circuit is used for outputting a 5V power supply voltage VDD. The power supply circuit supplies power for the MCU master control circuit and other circuits in the application.

The present application has been described in detail, and the principles and embodiments of the present application have been described herein using specific examples, which are provided only to help understand the present application and its core concept. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.

Claims

1. Lithium battery management circuit based on MCU includes:

the ID resistor identification circuit is connected with the main control chip and is used for detecting the resistance value of the ID resistor when the lithium battery discharges;

2. The MCU based lithium battery management circuit of claim 1, wherein the master control chip is FT62F 286A.

3. The MCU based lithium battery management circuit according to claim 1, wherein the ID resistance recognition circuit comprises a charging input positive terminal, a discharging output negative terminal, a fifth diode and a seventh diode, the positive terminal of the fifth diode is connected with the main control chip through a sixteenth resistor, the positive terminal of the seventh diode is connected with the negative terminal of the fifth diode, and an ID resistor is connected between the negative terminal of the seventh diode and the charging input negative terminal.

4. The MCU based lithium battery management circuit of claim 1 or 3, wherein the charging voltage electrical measurement circuit comprises a tenth capacitor and a twenty-fifth resistor; the tenth capacitor is connected with the twenty-fifth resistor in parallel, one end of the twenty-fifth resistor is connected with the main control chip, and the other end of the twenty-fifth resistor is grounded; and one end of the twenty-fifth resistor is connected with the cathode of the fifth diode through the nineteenth resistor.

5. The MCU-based lithium battery management circuit according to claim 1, wherein the discharge control circuit comprises an eleventh triode, a twelfth triode and a field effect tube group, wherein a collector of the twelfth triode is connected with the controllable power supply, and a base of the twelfth triode is connected with the main control chip through a twenty-fourth resistor; and the base electrode of the eleventh triode is connected with the collector electrode of the twelfth triode, the emitter electrode of the eleventh triode is connected with the emitter electrode of the twelfth triode, and the collector electrode of the eleventh triode is connected with the controllable power supply.

6. An MCU based lithium battery management circuit according to claim 5, wherein the collector of the eleventh transistor is connected to the gate of the field effect transistor bank, the emitter of the eleventh transistor is connected to the source of the field effect transistor bank, the gate of the field effect transistor bank is connected to the negative terminal of the discharge output, and the gate of the field effect transistor bank is connected to the positive terminal of the battery through the positive terminal of the fast recovery diode.

7. The MCU-based lithium battery management circuit according to claim 1, wherein the discharge current detection circuit comprises a twenty-third resistor, a twenty-eighth resistor and a ninth capacitor, one end of the ninth capacitor is grounded, the other end of the ninth capacitor is connected with a CIS pin of the main control chip, the CIS pin of the main control chip is connected with one end of the twenty-third resistor, the other end of the twenty-third resistor is connected with a P _ CIS pin of the main control chip, the CIS pin of the main control chip is connected with one end of the twenty-ninth resistor, and the other end of the twenty-ninth resistor is connected with an emitter of an eleventh triode.

8. The MCU-based lithium battery management circuit according to claim 4, wherein the discharge control circuit is connected with the ID resistance identification circuit through a negative feedback resistor group; and a negative feedback resistor group is connected between the other end of the twenty-fifth resistor and the emitting electrode of the eleventh triode.

9. The MCU-based lithium battery management circuit according to claim 1, further comprising a charge-discharge loop Wake-up circuit, wherein the charge-discharge loop Wake-up circuit comprises a tenth field effect transistor, a drain of the tenth field effect transistor is connected to a Wake pin of the main control chip, a source of the tenth field effect transistor is grounded, and a gate of the tenth field effect transistor is connected to the negative terminal of the discharge output through a twenty-first resistor and a seventh capacitor.

10. An MCU-based lithium battery management circuit as defined in claim 9, wherein the gate of the tenth fet is connected to the cathode of the seventh diode via a twelfth resistor and an eighth capacitor.