CN216959356U - Protection circuit for charging and discharging of lithium battery and lithium battery management system - Google Patents
Protection circuit for charging and discharging of lithium battery and lithium battery management system Download PDFInfo
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- CN216959356U CN216959356U CN202123123650.XU CN202123123650U CN216959356U CN 216959356 U CN216959356 U CN 216959356U CN 202123123650 U CN202123123650 U CN 202123123650U CN 216959356 U CN216959356 U CN 216959356U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The application relates to the technical field of lithium batteries, and discloses a protection circuit for charging and discharging of a lithium battery, which comprises: a detection circuit; a switching circuit; the first protection device is connected with the detection circuit, the switching circuit and the lithium battery, and controls the switching circuit to switch on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit and the voltage of the lithium battery; and the second protection device is connected with the detection circuit, the switching circuit and the lithium battery, and controls the switching circuit to switch on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit and the voltage of the lithium battery. The detection circuit and the protection device detect the state of the lithium battery. When the state of the lithium battery is abnormal, the charging or discharging loop is cut off through the switch circuit, and the effect of protecting the lithium battery is achieved. When one protection device fails, the other protection device can normally cut off a loop, so that the reliability of the lithium battery charging and discharging protection circuit is improved. The application also discloses a lithium battery management system.
Description
Technical Field
The application relates to the technical field of lithium batteries, for example, to a protection circuit for charging and discharging lithium batteries and a lithium battery management system.
Background
At present, lithium batteries are increasingly widely applied to portable devices due to the advantages of large capacity, long service life, no pollution and the like. However, in the using process, the lithium battery may have problems of overcharge, overdischarge and the like, and the service life of the lithium battery is influenced.
Lithium battery protection systems in the prior art include: the intelligent charging System comprises a main control circuit, a charging control circuit, a discharging control circuit, a sampling module, an SMBUS (System Management Bus) communication pin port and a Bluetooth module, wherein the charging control circuit and the discharging control circuit are electrically connected with the main control circuit; sampling module, SMBUS communication pin mouth and bluetooth module all with master control circuit electric connection.
In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:
the technology adopts a single control circuit to solve the problems of overcharge, overdischarge and overcurrent of the lithium battery in the charging and discharging processes. However, when the control circuit fails, the charging/discharging circuit of the lithium battery cannot be shut off, and the reliability of the protection circuit is low.
SUMMERY OF THE UTILITY MODEL
The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview nor is intended to identify key/critical elements or to delineate the scope of such embodiments but rather as a prelude to the more detailed description that is presented later.
The embodiment of the disclosure provides a protection circuit for charging and discharging a lithium battery and a lithium battery management system, so as to improve the reliability of the protection circuit for charging and discharging the lithium battery.
In some embodiments, the protection circuit for charging and discharging a lithium battery includes: a detection circuit; a switching circuit; the first protection device is connected with the detection circuit, the switching circuit and the lithium battery, and controls the switching circuit to switch on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit and the voltage of the lithium battery; and the second protection device is connected with the detection circuit, the switching circuit and the lithium battery, and controls the switching circuit to switch on/off a charging or discharging loop of the lithium battery according to the signal of the detection circuit and the voltage of the lithium battery.
Optionally, the detection circuit comprises: one end of the first thermistor is connected with the first protection device, and the other end of the first thermistor is connected with the ground wire; one end of the second thermistor is connected with the second protection device, and the other end of the second thermistor is connected with the ground wire; and one end of the current sampling resistor is connected with the first protection device and the second protection device, and the other end of the current sampling resistor is connected with the ground wire, the first protection device and the second protection device.
Optionally, the switching circuit comprises: the grid of the first field effect transistor is connected with the first protection device; the grid of the second field effect transistor is connected with the second protection device, the drain electrode of the second field effect transistor is connected with the non-grounding end of the current sampling resistor, and the source electrode of the second field effect transistor is connected with the drain electrode of the first field effect transistor; the grid of the third field effect transistor is connected with the first protection device; and the grid electrode of the fourth field effect transistor is connected with the second protection device, the drain electrode of the fourth field effect transistor is connected with the source electrode of the third field effect transistor, and the source electrode of the fourth field effect transistor is connected with the drain electrode of the second field effect transistor.
Optionally, the power supply pin of the first protection device is connected to the power supply pin of the second protection device, and the ground pin of the first protection device and the ground pin of the second protection device are connected to the ground line.
Optionally, the method further comprises: a first fuse; a second fuse; and the cathode of the first diode is connected with power supply pins of the first protection device and the second protection device, and the anode of the first diode is connected with one end of the first fuse and one end of the second fuse.
Optionally, the method further comprises: and the communication circuit is connected with the first protection device and the second protection device and is used for sending the data of the lithium battery.
Optionally, the communication circuit comprises: the microcontroller is connected with the first protection device and the second protection device, and the grounding pin is connected with the ground wire; and the isolation transceiver is connected with the microcontroller.
Optionally, the method further comprises: the input pin of the direct current converter is connected with the cathode of the first diode, and the grounding pin of the direct current converter is connected with the ground wire; and the anode of the second diode is connected with an output pin of the direct current converter, and the cathode of the second diode is connected with a power supply pin of the microcontroller.
Optionally, the method further comprises: the head end of the primary side of the transformer is connected with an output pin of the direct current converter, the tail end of the primary side of the transformer is connected with a ground wire, the head end of the secondary side of the transformer is connected with a power supply pin of the isolation transceiver, and the tail end of the secondary side of the transformer is connected with a grounding pin of the isolation transceiver.
In some embodiments, the lithium battery management system comprises the protection circuit for charging and discharging the lithium battery.
The protection circuit for charging and discharging of the lithium battery and the lithium battery management system provided by the embodiment of the disclosure can realize the following technical effects:
the detection circuit detects the temperature and the current state of the lithium battery, and the protection device detects the voltage of each lithium battery. When the lithium battery is overcharged, overdischarged, overcurrent or abnormal in temperature, the charging or discharging loop is cut off through the switch circuit, and the lithium battery is protected. When one protection device fails and cannot abnormally work in the charging/discharging of the lithium battery, the other protection device can normally cut off a loop so as to improve the reliability of the charging/discharging protection circuit of the lithium battery.
The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the accompanying drawings and not in limitation thereof, in which elements having the same reference numeral designations are shown as like elements and not in limitation thereof, and wherein:
fig. 1 is a schematic structural diagram of a protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure;
fig. 6 is a schematic structural diagram of another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure.
Reference numerals:
1: a detection circuit; 2: a switching circuit; 3: a first protection device; 4: a second protection device; 5: a communication circuit; 6: a DC converter; 7: a display screen; 51: a microcontroller; 52: an isolation transceiver; RT 1: a first thermistor; RT 2: a second thermistor; RX 1: a current sampling resistor; q1: a first field effect transistor; q2: a second field effect transistor; q3: a third field effect transistor; q4: a fourth field effect transistor; f1: a first fuse; f2: a second fuse; d1: a first diode; d2: a second diode; t1: a transformer; b1: a first section of lithium battery; b2: a second lithium battery; b13: a thirteenth lithium battery; v1: a first voltage detection pin; v2: a second voltage detection pin; v13: a thirteenth voltage detection pin; VCC: a power supply pin; GND: a ground pin; GND 1: a ground wire; CHG: a charging control pin; a DSG: a discharge control pin; TS: a temperature detection pin; ISN: a negative current detection pin; ISP: a positive current detection pin; and (2) SCL: a serial clock pin; SDA: a serial data pin; TXD: a data transmission pin; RXD: receiving a data pin; TXDE: the isolated side sends a data pin; RXDE: the isolation side receives a data pin; IN: inputting a pin; OUT: and an output pin.
Detailed Description
So that the manner in which the features and advantages of the embodiments of the present disclosure can be understood in detail, a more particular description of the embodiments of the disclosure, briefly summarized above, may be had by reference to the appended drawings, which are included to illustrate, but are not intended to limit the embodiments of the disclosure. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may be practiced without these details. In other instances, well-known structures and devices may be shown in simplified form in order to simplify the drawing.
The terms "first," "second," and the like in the description and in the claims, and the above-described drawings of embodiments of the present disclosure, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged as appropriate for the embodiments of the disclosure described herein. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions.
In the embodiments of the present disclosure, terms "upper", "lower", "inner", "middle", "outer", "front", "rear", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings. These terms are used primarily to better describe the disclosed embodiments and their examples and are not intended to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation. Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meanings of these terms in the embodiments of the present disclosure can be understood by those of ordinary skill in the art as appropriate.
In addition, the terms "disposed," "connected," and "secured" are to be construed broadly. For example, "connected" may be a fixed connection, a detachable connection, or a unitary construction; may be a mechanical connection, or a connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. Specific meanings of the above terms in the disclosed embodiments can be understood by those of ordinary skill in the art according to specific situations.
The term "plurality" means two or more, unless otherwise specified.
In the embodiment of the present disclosure, the character "/" indicates that the preceding and following objects are in an or relationship. For example, A/B represents: a or B.
The term "and/or" is an associative relationship that describes objects, meaning that three relationships may exist. For example, a and/or B, represents: a or B, or A and B.
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other.
With reference to fig. 1, an embodiment of the present disclosure provides a protection circuit for charging and discharging a lithium battery, including a detection circuit 1, a switch circuit 2, a first protection device 3, and a second protection device 4. The first protection device 3 is connected to the detection circuit 1, the switch circuit 2, and the lithium battery, and controls the switch circuit 2 to turn on/off a charge or discharge circuit of the lithium battery according to a signal of the detection circuit 1 and a voltage of the lithium battery. The second protection device 4 is connected with the detection circuit 1, the switch circuit 2 and the lithium battery, and controls the switch circuit 2 to turn on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit 1 and a voltage of the lithium battery.
By adopting the protection circuit for charging and discharging of the lithium battery provided by the embodiment of the disclosure, the detection circuit detects the temperature and the current state of the lithium battery, and the protection device detects the voltage of each lithium battery. When the lithium battery is overcharged, overdischarged, overcurrent or abnormal in temperature, the charging or discharging loop is cut off through the switch circuit, and the lithium battery is protected. When one protection device fails and cannot abnormally work in the charging/discharging of the lithium battery, the other protection device can normally cut off a loop so as to improve the reliability of the charging/discharging protection circuit of the lithium battery.
The product model of the first protection device 3 may be OZ3714, or OZ 7714. The product model of the second protection device 4 may be OZ3714 or OZ 7714.
The protection circuit for charging and discharging of the lithium battery provided by the embodiment of the disclosure adopts 2 protection devices. For the protection circuit which comprises a plurality of protection devices and is used for charging and discharging of the lithium battery, the protection circuit can be realized only by connecting other protection devices with other circuits according to the connection mode of the first protection device 3 or the second protection device 4. The more protection devices are adopted, the higher the reliability of the lithium battery protection circuit is, and the higher the cost of the circuit is.
Referring to fig. 2, a plurality of voltage detection pins of the first protection device 3 are respectively connected to the positive electrode of each lithium battery, and a plurality of voltage detection pins of the second protection device 4 are respectively connected to the positive electrode of each lithium battery. The first protection device 3 and the second protection device 4 are switched to any one lithium battery by using an internal analog switch, and an analog signal of voltage is converted into a digital signal through analog-to-digital conversion, so that the voltage of each lithium battery is detected.
Each lithium battery is one of a first lithium battery B1, a second lithium battery B2 and a thirteenth lithium battery B13. The thirteen lithium batteries are only examples, and the number of the lithium batteries can be increased or decreased according to actual needs.
A plurality of voltage detection pins of the first protection device 3 are respectively connected with the anode of each lithium battery to represent the voltage, the first voltage detection pin to the nth voltage detection pin are respectively connected with the anodes of the first lithium battery to the nth lithium battery, wherein n represents the maximum number of lithium batteries in the current charging and discharging loop. For example, the first voltage detection pin V1 of the first protection device 3 is connected to the positive electrode of the first lithium battery B1, the second voltage detection pin V2 is connected to the positive electrode of the second lithium battery B2, and the thirteenth voltage detection pin V13 is connected to the positive electrode of the thirteenth lithium battery B13. The connection mode of the voltage detection pin of the second protection device 4 and the lithium battery is the same as that of the first protection device 3, and is not described again. The n lithium batteries are connected in series to form the lithium battery pack.
Specifically, in the lithium battery charging process, when the first protection device 3 and the second protection device 4 detect that at least one lithium battery has overvoltage or undervoltage, the first protection device 3 and the second protection device 4 send low level signals through the charging control pin CHG to cut off the switch circuit 2. When one of the protection devices, for example, the first protection device 3 is damaged, the switching circuit 2 cannot be normally cut off. At this time, the second protection device 4 can send a low level signal to cut off the switch circuit 2 through the charging control pin CHG, so that the reliability of the lithium battery charging and discharging protection circuit is improved.
Optionally, the detection circuit 1 comprises a first thermistor RT1, a second thermistor RT2 and a current sampling resistor RX 1. One end of the first thermistor RT1 is connected to the temperature detection pin TS of the first protection device 3, and the other end is connected to the ground GND 1. One end of the second thermistor RT2 is connected to the temperature detection pin TS of the second protection device 4, and the other end is connected to the ground GND 1. One end of the current sampling resistor RX1 is connected to the negative current detection pins ISN of the first and second protection devices 3 and 4, and the other end is connected to the ground GND1 and the positive current detection pins ISP of the first and second protection devices 3 and 4. Therefore, the temperature of the lithium battery is collected by the thermistor, the charging or discharging current of the lithium battery is collected by the sampling resistor, the accuracy of the temperature and the current can meet the requirements of a lithium battery charging and discharging protection circuit, and the detection circuit is simple in structure and low in cost.
According to the protection circuit for charging and discharging of the lithium battery, only one type of charging and discharging process exists at the same time, and the lithium battery cannot supply power to a load while the lithium battery is charged. I.e. no load in case of a charger being connected. In the case of a load, the charger is not connected. The charger and the load are drawn together in the figure to show only the connection relationship between the protection circuit for charging and discharging the lithium battery and the charger and the load during the charging or discharging process. When the charger and the load are connected at the same time, the charger supplies power to the load on one hand and charges the lithium battery on the other hand.
Optionally, the switching circuit 2 includes a first fet Q1, a second fet Q2, a third fet Q3 and a fourth fet Q4. The gate of the first fet Q1 is connected to the charge control pin CHG of the first protection device 3, and the source is connected to the negative electrode of the charger. The gate of the second fet Q2 is connected to the charge control pin CHG of the second protection device 4, the drain is connected to the non-ground terminal of the current sampling resistor RX1, and the source is connected to the drain of the first fet Q1. The gate of the third fet Q3 is connected to the discharge control pin DSG of the first protection device 3, and the drain is connected to the negative electrode of the load. The gate of the fourth fet Q4 is connected to the discharge control pin DSG of the second protection device 4, the drain is connected to the source of the third fet Q3, and the source is connected to the drain of the second fet Q2. Therefore, when the lithium battery is abnormal in charging and discharging, the charging or discharging loop of the lithium battery is cut off by turning off the field effect transistor, and the cutting-off speed is high. In the charging or discharging loop, two field effect transistors are connected in series in the loop. When one field effect transistor fails and cannot act, the other field effect transistor can cut off a loop, and the reliability of the lithium battery charging and discharging protection circuit is improved.
Specifically, in the discharging process of the lithium battery, the third field effect transistor Q3 has a fault and cannot be turned off. The first protection device 3 and the second protection device 4 detect that the current of the lithium battery is too high, and the problem of discharging overcurrent exists. The first protection device 3 sends a turn-off signal to the third fet Q3, and the third fet Q3 cannot turn off due to a fault. The second protection device 4 sends a turn-off signal to the fourth field effect transistor Q4, and the fourth field effect transistor Q4 cuts off a discharge loop, so that the lithium battery is protected.
Alternatively, the power supply pin VCC of the first protection device 3 and the power supply pin VCC of the second protection device 4 are connected, and the ground pin GND of the first protection device 3 and the ground pin GND of the second protection device 4 are connected to the ground GND 1. Therefore, the first protection device and the second protection device adopt the same power supply source, and the circuit structure is simple and the cost is low.
Optionally, the protection circuit for charging and discharging the lithium battery further includes a first fuse F1, a second fuse F2, and a first diode D1. The cathode of the first diode D1 is connected to the power supply pins VCC of the first protection device 3 and the second protection device 4, and the anode is connected to one end of the first fuse F1, one end of the second fuse F2, and the anode of the lithium battery pack. The other end of the first fuse F1 is connected to the positive electrode of the charger. The other end of the second fuse F2 is connected to the positive pole of the load. Therefore, the fuse can cut off a loop when the circuit is in overcurrent and the first protection device and the second protection device are both in fault, and the reliability of the lithium battery charging and discharging protection circuit is improved. When the circuit is under the serious condition of electromagnetic interference, the first diode can prevent the current from being output from the power supply pins of the first protection device and the second protection device, and the first protection device and the second protection device are prevented from being damaged.
Optionally, the negative electrode of the lithium battery pack is connected to ground GND 1.
With reference to fig. 3, another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure includes a detection circuit 1, a switch circuit 2, a first protection device 3, a second protection device 4, and a communication circuit 5. The first protection device 3 is connected to the detection circuit 1, the switch circuit 2, and the lithium battery, and controls the switch circuit 2 to turn on/off a charge or discharge circuit of the lithium battery according to a signal of the detection circuit 1 and a voltage of the lithium battery. The second protection device 4 is connected with the detection circuit 1, the switch circuit 2 and the lithium battery, and controls the switch circuit 2 to turn on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit 1 and a voltage of the lithium battery. The communication circuit 5 is connected with the first protection device 3 and the second protection device 4, and sends data of the lithium battery according to voltage, current and temperature signals of the lithium battery detected by the first protection device 3 and the second protection device 4.
By adopting the protection circuit for charging and discharging of the lithium battery provided by the embodiment of the disclosure, the detection circuit detects the temperature and the current state of the lithium battery, and the protection device detects the voltage of each lithium battery. When the lithium battery is overcharged, overdischarged, overcurrent or abnormal in temperature, the charging or discharging loop is cut off through the switch circuit, and the lithium battery is protected. When one protection device fails and cannot abnormally work in the charging/discharging of the lithium battery, the other protection device can normally cut off a loop so as to improve the reliability of the charging/discharging protection circuit of the lithium battery. The communication circuit can send the voltage, current and temperature data of the lithium battery to the user, and the user can know the state of the lithium battery in real time according to the data, so that the user can use the lithium battery at an expected time or charge the lithium battery conveniently.
Specifically, when the user knows that the charging capacity of the lithium battery has reached 85% according to the data, the user considers that the charging capacity is sufficient. The user manually disconnects the charger from the protection circuit and uses the lithium battery to power the load. When the user knows that the discharge capacity of the lithium battery has decreased to 25% according to the data, the lithium battery is worried about the life reduction due to the low capacity. The user manually disconnects the load from the protection circuit and charges the lithium battery using a charger.
As shown in connection with fig. 4, optionally, the communication circuit 5 comprises a microcontroller 51 and an isolation transceiver 52. The serial clock pin SCL of the microcontroller 51 is connected to the serial clock pin SCL of the first protection device 3 and the serial clock pin SCL of the second protection device 4, the serial data pin SDA is connected to the serial data pin SDA of the first protection device 3 and the serial data pin SDA of the second protection device 4, and the ground pin GND is connected to the ground GND 1. The transmit data pin TXD of the isolator transceiver 52 is connected to the receive data pin RXD of the microcontroller 51, and the receive data pin RXD is connected to the transmit data pin TXD of the microcontroller 51. Therefore, the microcontroller and the isolation transceiver are used as devices for lithium battery data transmission, the circuit structure is simple, and the cost is low.
The product model of the microcontroller 51 may be STM32F042F6P6, or may also be STM32F103C8T 6. The product model of the isolator transceiver 52 may be ISO1050, or, TDA51S485 HC.
The isolator transceiver 52 may be adapted to various bus interfaces of users, such as an RS485 (recommended Standard) bus, a CAN (Controller Area Network) bus, a wireless transceiver module, and the like. Therefore, the isolation transceiver has strong adaptability and wide application range.
Specifically, the microcontroller 51 obtains and converts the voltage data, the current data, and the temperature data of the lithium batteries of the first protection device 3 and the second protection device 4 through the serial data pin SDA and the serial clock pin SCL, and determines whether the first protection device 3 and the second protection device 4 have a fault. The microcontroller sends the data of the lithium battery to the isolation transceiver 52 through the data sending pin TXD and the data receiving pin RXD, the isolation transceiver 52 sends the data of the lithium battery to a user through a bus interface, and the user judges whether to perform manual control according to the voltage, the current and the temperature of the lithium battery and whether the first protection device 3 and the second protection device 4 are normal or not. For example, a user manually replaces a new protection device when one protection device fails. And when the two protection devices are in failure and the voltage, the current and/or the temperature of the lithium battery are abnormal, the user manually cuts off the loop.
Optionally, the protection circuit for charging and discharging the lithium battery further includes a dc converter 6 and a second diode D2. An input pin IN of the dc converter 6 is connected to a cathode of the first diode D1, and a ground pin GND is connected to a ground line GND 1. The anode of the second diode D2 is connected to the output terminal OUT of the dc converter 6, and the cathode is connected to the power supply terminal VCC of the microcontroller 51. Therefore, the direct current converter can convert the voltage of the lithium battery into 5V direct current voltage to stably supply power to the microcontroller. When the circuit is under the serious condition of electromagnetic interference, the second diode can prevent the current from being output from the power supply pin of the microcontroller, and the microcontroller is prevented from being damaged.
The model of the dc converter 6 may be LM5008, or SL 3036H.
Optionally, the protection circuit for charging and discharging the lithium battery further includes a transformer T1. The primary side of the transformer T1 has a head end connected to an output pin OUT of the dc converter 6, a tail end connected to a ground GND1, a head end connected to a power supply pin VCC of the isolation transceiver 52, and a tail end connected to a ground pin GND of the isolation transceiver 52. Therefore, the power supply of the isolation transceiver is isolated from the power supply of other devices through the transformer, and harmonic waves are prevented from interfering the isolation transceiver.
Wherein, the turn ratio of the primary side and the secondary side of the transformer T1 is 1: 1.
With reference to fig. 5, another protection circuit for charging and discharging a lithium battery according to an embodiment of the present disclosure includes a detection circuit 1, a switch circuit 2, a first protection device 3, a second protection device 4, a communication circuit 5, and a display 7. The first protection device 3 is connected to the detection circuit 1, the switch circuit 2, and the lithium battery, and controls the switch circuit 2 to turn on/off a charge or discharge circuit of the lithium battery according to a signal of the detection circuit 1 and a voltage of the lithium battery. The second protection device 4 is connected with the detection circuit 1, the switch circuit 2 and the lithium battery, and controls the switch circuit 2 to turn on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit 1 and a voltage of the lithium battery. The communication circuit 5 is connected with the first protection device 3 and the second protection device 4, and sends data of the lithium battery according to the voltage, current and temperature signals of the lithium battery detected by the first protection device 3 and the second protection device 4. The display screen 7 is connected with the communication circuit 5 and used for displaying data of the lithium battery.
By adopting the protection circuit for charging and discharging of the lithium battery provided by the embodiment of the disclosure, the detection circuit detects the temperature and the current state of the lithium battery, and the protection device detects the voltage of each lithium battery. When the lithium battery is overcharged, overdischarged, overcurrent or abnormal in temperature, the charging or discharging loop is cut off through the switch circuit, and the lithium battery is protected. When one protection device fails and cannot abnormally work in the charging/discharging of the lithium battery, the other protection device can normally cut off a loop so as to improve the reliability of the charging/discharging protection circuit of the lithium battery. The communication circuit can transmit the voltage, the current and the temperature data of the lithium battery to the display screen, and a user can know the state of the lithium battery in real time according to the data of the display screen, so that the user can use the lithium battery at an expected time or charge the lithium battery conveniently.
The product model of the display screen 7 may be DC80480KM043_1111_0X (T/C), or DC80480M050_1111_0X (T/C/N).
As shown in fig. 6, optionally, the power supply pin VCC of the display 7 is connected to the load connection terminal of the second fuse F2, the ground pin GND is connected to the drain of the third fet Q3, the transmit data pin TXD is connected to the isolation-side receive data pin RXDE of the isolation transceiver 52, and the receive data pin RXD is connected to the isolation-side transmit data pin TXDE of the isolation transceiver 52. Therefore, the display screen is powered by the lithium battery or the charger, an additional power supply circuit is not needed, and the cost is low. And displaying the state of the lithium battery and the information whether the first protection device and the second protection device are normal or not by receiving the data of the isolation transceiver.
Specifically, during the charging process of the lithium battery, when the first protection device 3 fails, the microcontroller 51 transmits the failure information of the first protection device 3 to the display screen 7 through the isolation transceiver 52. The display screen 7 displays the current voltage, current and temperature of the lithium battery, and the information that the first protection device 3 is in failure and the second protection device 4 is normal. The user changes the first protection device 3 according to the information of the display screen 7, and the reliability of the lithium battery charging and discharging protection circuit is improved.
The embodiment of the disclosure provides a lithium battery management system, which comprises a protection circuit for charging and discharging of a lithium battery provided by any embodiment. The lithium battery management system can normally cut off a circuit through another protection device when one protection device fails and cannot play a role in protection, so that the reliability of the lithium battery charging and discharging protection circuit is improved. The lithium battery management system provided by the embodiment of the utility model comprises the lithium battery protection system used in the embodiment, so that the lithium battery management system provided by the embodiment of the utility model also has the beneficial effects described in the embodiment.
The above description and drawings sufficiently illustrate embodiments of the disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The embodiments of the present disclosure are not limited to the structures that have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.
Claims (10)
1. A protection circuit for charging and discharging a lithium battery, comprising:
a detection circuit (1);
a switching circuit (2);
the first protection device (3) is connected with the detection circuit (1), the switch circuit (2) and the lithium battery, and controls the switch circuit (2) to switch on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit (1) and the voltage of the lithium battery;
and the second protection device (4) is connected with the detection circuit (1), the switch circuit (2) and the lithium battery, and controls the switch circuit (2) to switch on/off a charging or discharging loop of the lithium battery according to a signal of the detection circuit (1) and the voltage of the lithium battery.
2. A circuit according to claim 1, characterized in that the detection circuit (1) comprises:
a first thermistor (RT1) having one end connected to the first protection device (3) and the other end connected to a ground (GND 1);
a second thermistor (RT2), one end of which is connected to the second protection device (4) and the other end of which is connected to the ground (GND 1);
and one end of the current sampling resistor (RX1) is connected with the first protection device (3) and the second protection device (4), and the other end of the current sampling resistor is connected with the ground wire (GND1), the first protection device (3) and the second protection device (4).
3. A circuit according to claim 2, characterized in that the switching circuit (2) comprises:
a first field effect transistor (Q1) having a gate connected to the first protection device (3);
a second field effect transistor (Q2), wherein the grid electrode is connected with the second protection device (4), the drain electrode is connected with the non-grounding end of the current sampling resistor (RX1), and the source electrode is connected with the drain electrode of the first field effect transistor (Q1);
a third field effect transistor (Q3) having a gate connected to the first protection device (3);
and the grid of the fourth field effect transistor (Q4) is connected with the second protection device (4), the drain of the fourth field effect transistor is connected with the source electrode of the third field effect transistor (Q3), and the source electrode of the fourth field effect transistor is connected with the drain electrode of the second field effect transistor (Q2).
4. The circuit according to claim 1, characterized in that the supply pin (VCC) of the first protection device (3) and the supply pin (VCC) of the second protection device (4) are connected, and the ground pin (GND) of the first protection device (3) and the ground pin (GND) of the second protection device (4) are connected to the ground line (GND 1).
5. The circuit of any of claims 1 to 4, further comprising:
a first fuse (F1);
a second fuse (F2);
and the cathode of the first diode (D1) is connected with the power supply pin (VCC) of the first protection device (3) and the second protection device (4), and the anode of the first diode (D1) is connected with one end of the first fuse (F1) and one end of the second fuse (F2).
6. The circuit of claim 5, further comprising:
and the communication circuit (5) is connected with the first protection device (3) and the second protection device (4) and is used for transmitting the data of the lithium battery.
7. The circuit according to claim 6, characterized in that the communication circuit (5) comprises:
the microcontroller (51) is connected with the first protection device (3) and the second protection device (4), and the grounding pin (GND) is connected with the ground wire (GND 1);
and an isolation transceiver (52) connected to the microcontroller (51).
8. The circuit of claim 7, further comprising:
a DC converter (6) having an input pin (IN) connected to the cathode of the first diode (D1), and a ground pin (GND) connected to a ground line (GND 1);
and a second diode (D2), the anode of which is connected with the output pin (OUT) of the direct current converter (6), and the cathode of which is connected with the power supply pin (VCC) of the microcontroller (51).
9. The circuit of claim 8, further comprising:
and the head end of the primary side of the transformer (T1) is connected with an output pin (OUT) of the direct current converter (6), the tail end of the transformer is connected with a ground wire (GND1), the head end of the secondary side of the transformer is connected with a power supply pin (VCC) of the isolation transceiver (52), and the tail end of the transformer is connected with a ground pin (GND) of the isolation transceiver (52).
10. A lithium battery management system comprising the protection circuit for charging and discharging a lithium battery according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123123650.XU CN216959356U (en) | 2021-12-13 | 2021-12-13 | Protection circuit for charging and discharging of lithium battery and lithium battery management system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202123123650.XU CN216959356U (en) | 2021-12-13 | 2021-12-13 | Protection circuit for charging and discharging of lithium battery and lithium battery management system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115954987A (en) * | 2023-02-03 | 2023-04-11 | 深圳市凌鑫电子有限公司 | Lithium battery charging secondary protection circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115954987A (en) * | 2023-02-03 | 2023-04-11 | 深圳市凌鑫电子有限公司 | Lithium battery charging secondary protection circuit |
| CN115954987B (en) * | 2023-02-03 | 2023-11-03 | 深圳市凌鑫电子有限公司 | Secondary protection circuit for lithium battery charging |
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