Lithium battery charging and discharging management system

Abstract

The utility model provides a lithium battery charging and discharging management system. The lithium battery charging and discharging management system comprises an input unit, a DC-DC converter circuit, a charging protection circuit, a discharging protection circuit, a temperature and humidity monitoring module, an MCU processor and a dynamic load, the input unit is used for providing a power supply, the charging protection circuit is connected with the input unit, the discharging protection circuit is connected with the DC-DC converter circuit, the discharging protection circuit is further connected with the MCU processor, the DC-DC converter circuit is connected with the MCU processor, and the charging protection circuit is connected with the MCU processor. The working state of the lithium battery can be monitored in real time, and the charging and discharging processes of the battery are effectively managed through the charging protection circuit and the discharging protection circuit.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery management systems, and in particular relates to a lithium battery charge and discharge management system. Background Art

[0002] Lithium batteries are widely used in electric vehicles, smartphones, laptops, and other applications due to their high energy density, long cycle life, and environmentally friendly properties. However, their sensitivity to voltage, current, and temperature during charge and discharge exposes them to risks such as overcharge, overdischarge, and overheating. This not only affects battery performance and service life but can also lead to safety incidents. Therefore, developing effective lithium battery charge and discharge management systems is crucial.

[0003] In the prior art, lithium battery charge and discharge management typically relies on a battery management system (BMS). For example, the management system proposed by Wang Tianfu et al. in "Design and Implementation of an Intelligent Management System for Charging and Discharging Power Lithium Battery Packs" (Journal of the University of Electronic Science and Technology of China, Vol. 35, No. 9, 2011, pp. 1069-1071) primarily consists of a battery cell voltage detection circuit, a main controller (FPGA), a current detection circuit, a temperature detection circuit, and a charge and discharge balancing circuit. The voltage detection circuit uses the LTC6802 chip, which accurately measures the voltage of each cell and communicates with the main controller via an SPI interface. The current detection circuit monitors the battery pack current using a current sensor and an A / D converter, while the temperature detection uses a DS18B20 temperature sensor attached to the outer casing of each cell to monitor the battery temperature in real time. The charge and discharge balancing circuit uses a resistor shunt balancing method, controlling the balancing charge and discharge circuit via the MOSFETs within the LTC6802 to maintain voltage balance in the battery pack. By monitoring the battery voltage, temperature, and current, this system controls the charge and discharge process to prevent overcharging and over-discharging. Another related study, "Research and Design of a Lithium Battery Charging and Discharging System Based on STM32," was presented by Wei Lijun et al. This system uses the RT9545 chip for battery protection, the BQ24230 chip for charge and discharge path management, the BQ27410 chip for status information collection, and the LMR62421 chip for DC-DC boost.

[0004] The management system proposed by Wang Tianfu et al. in "Design and Implementation of an Intelligent Management System for Charging and Discharging Power Lithium-ion Battery Packs" (Journal of the University of Electronic Science and Technology of China, Vol. 35, No. 9, 2011, pp. 1069-1071) uses a resistor-shunting balancing method that results in power loss, potentially affecting overall energy efficiency. Furthermore, the LTC6802 chip's scalability may be limited in large-scale battery pack applications, resulting in insufficient versatility and flexibility in complex operating conditions.

[0005] The system proposed by Wei Lijun et al. in "Research and Design of a Lithium Battery Charging and Discharging System Based on STM32" achieves comprehensive management of lithium battery charging and discharging through multiple chips. However, its complex multi-chip design increases system cost and complexity. The coordination between the chips may be affected by differences in electrical characteristics, which may reduce system stability and reliability. Furthermore, the accuracy of battery status information collection needs to be further improved. Utility Model Content

[0006] In order to solve the above problems existing in the prior art, the utility model provides a lithium battery charge and discharge management system to achieve safer, more efficient and more cost-effective lithium battery charge and discharge management.

[0007] A lithium battery charge and discharge management system, comprising: an input unit, a DC-DC converter circuit, a charging protection circuit, a discharging protection circuit, a temperature and humidity monitoring module, an MCU processor, and a dynamic load; the input unit is used to provide power, the charging protection circuit is connected to the input unit, the discharging protection circuit is connected to the DC-DC converter circuit, the discharging protection circuit is also connected to the MCU processor, the DC-DC converter circuit is connected to the MCU processor, and the charging protection circuit is connected to the MCU processor;

[0008] The charging protection circuit is composed of a DC power supply DC, a voltage detection chip GC1, a TVS diode TVS1, a lithium battery BT, a capacitor C5, a capacitor C6, a capacitor C7, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a PMOS transistor Q1, an NMOS transistor Q2, an NMOS transistor Q3 and a diode TD1. The positive electrode of the DC power supply DC is connected to the source of the PMOS transistor Q1 through the diode TD1, the drain of the PMOS transistor Q1 is connected to the positive electrode of the lithium battery BT, the gate of the PMOS transistor Q1 is connected to the drain of the NMOS transistor Q2, the ground terminal of the voltage detection chip GC1 is connected to the negative electrode of the lithium battery BT, the output terminal of the voltage detection chip GC1 is connected to the gate of the NMOS transistor Q3 through the resistor R8, and the NMOS The transistor Q2 and the NMOS transistor Q3 together constitute a dual NMOS structure. The sources of the NMOS transistors Q2 and Q3 are both grounded. The TVS diode TVS1 is connected in parallel between the positive and negative electrodes of the lithium battery BT. The positive electrode of the TVS diode TVS1 is connected to the positive electrode of the lithium battery BT, and the negative electrode of the TVS diode TVS1 is connected to the negative electrode of the lithium battery BT. The resistor R5 is connected between the positive electrode of the input unit DC and the gate of the NMOS transistor Q2. The resistor R6 is connected between the positive electrode of the DC power supply DC and the drain of the NMOS transistor Q2. The resistor R7 is connected between the negative electrode of the DC power supply DC and the gate of the NMOS transistor Q3. The capacitors C5, C6, and C7 are connected in parallel between the positive and negative electrodes of the lithium battery BT. The negative electrode of the DC power supply DC is grounded.

[0009] Furthermore, the DC-DC converter circuit includes a DC-DC converter, resistors R1, R2, R3, R4, capacitors C1, C2, C3, C4, an inductor L1 and a lithium battery BT. The input terminal VIN of the DC-DC converter is connected to the positive electrode of the lithium battery BT, the negative electrode of the BT is grounded, one end of the capacitors C1, C2, C3, C4, R2 and R4 is grounded, the other ends of the capacitors C1 and C2 are connected to the input terminal VIN of the DC-DC converter, the other end of the resistor R2 is connected to the EN terminal of the DC-DC converter, one end of R1 is connected to the EN terminal of the DC-DC converter, the other ends of the capacitors C3 and C4 are connected to the output terminal VOUT of the DC-DC converter, the other end of the resistor R4 is connected to the FB terminal of the DC-DC converter, one end of the resistor R3 is connected to the FB terminal of the DC-DC converter, and the other end of the resistor R3 is connected to the output terminal VOUT of the DC-DC converter. The inductor L1 is connected between the LX1 pin and the LX2 pin of the DC-DC converter.

[0010] Furthermore, the discharge protection circuit includes a lithium battery BT, a voltage detection chip GC2, diodes TD2, TD3, resistors R9, R10, and a capacitor C8. The positive and negative electrodes of the lithium battery BT are respectively connected to the input end and the ground end of the voltage detection chip GC2, the positive electrode of the diode TD3 is connected to the output end of the voltage detection chip GC3, the negative electrode of the diode TD3 is connected to the negative electrode of the diode TD2, one end of the resistor R10 and the capacitor C8 are connected to the negative electrode of the lithium battery BT, the other end of the resistor R10 and the capacitor C8 are connected, one end of the resistor R9 is connected to the negative electrode of the diode TD2, and the other end of the resistor R9 is connected to the resistor R10.

[0011] Furthermore, the input unit is an adapter, a power socket or solar power supply.

[0012] Furthermore, the lithium battery BT is a single-cell lithium battery, or a unit composed of multiple lithium battery cells.

[0013] Furthermore, the model of the voltage detection chip GC1 is BL8506-35CRM, and the model of the voltage monitoring chip GC2 is BL8506-30CRM.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] 1. This application can monitor the working status of lithium batteries in real time and effectively manage the charging and discharging process of the battery through charging protection and discharging protection circuits;

[0016] 2. The electronic devices used in the system design improve the system's response speed and reduce costs by selecting cost-effective domestically produced chips;

[0017] 3. The system's simple design makes the entire system more compact, reduces the number of chips required, improves reliability, and reduces the safety risks caused by battery failure;

[0018] 4. By precisely controlling the charge and discharge process, this application reduces damage to lithium batteries, extends battery life, reduces user maintenance costs, and achieves low-energy operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural block diagram of a lithium battery charge and discharge management system of the utility model;

[0020] Figure 2 This is a schematic diagram of the charging protection circuit of a lithium battery charging and discharging management system of the utility model;

[0021] Figure 3This is a schematic diagram of the DC-DC converter circuit of a lithium battery charge and discharge management system of the utility model;

[0022] Figure 4 This is a schematic diagram of a discharge protection circuit for a lithium battery charge and discharge management system of the present utility model. DETAILED DESCRIPTION

[0023] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 and 2 As shown, a lithium battery charge and discharge management system includes: an input unit, a DC-DC converter circuit, a charging protection circuit, a discharging protection circuit, a temperature and humidity monitoring module, an MCU processor, and a dynamic load; the input unit is used to provide power, the charging protection circuit is connected to the input unit, the discharging protection circuit is connected to the DC-DC converter circuit, the discharging protection circuit is also connected to the MCU processor, the DC-DC converter circuit is connected to the MCU processor, and the charging protection circuit is connected to the MCU processor;

[0025] The charging protection circuit is composed of a DC power supply DC, a voltage detection chip GC1, a TVS diode TVS1, a lithium battery BT, a capacitor C5, a capacitor C6, a capacitor C7, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a PMOS transistor Q1, an NMOS transistor Q2, an NMOS transistor Q3 and a diode TD1. The positive electrode of the DC power supply DC is connected to the source of the PMOS transistor Q1 through the diode TD1, the drain of the PMOS transistor Q1 is connected to the positive electrode of the lithium battery BT, the gate of the PMOS transistor Q1 is connected to the drain of the NMOS transistor Q2, the ground terminal of the voltage detection chip GC1 is connected to the negative electrode of the lithium battery BT, the output terminal of the voltage detection chip GC1 is connected to the gate of the NMOS transistor Q3 through the resistor R8, and the NMOS The transistor Q2 and the NMOS transistor Q3 together constitute a dual NMOS structure. The sources of the NMOS transistors Q2 and Q3 are both grounded. The TVS diode TVS1 is connected in parallel between the positive and negative electrodes of the lithium battery BT. The positive electrode of the TVS diode TVS1 is connected to the positive electrode of the lithium battery BT, and the negative electrode of the TVS diode TVS1 is connected to the negative electrode of the lithium battery BT. The resistor R5 is connected between the positive electrode of the input unit DC and the gate of the NMOS transistor Q2. The resistor R6 is connected between the positive electrode of the DC power supply DC and the drain of the NMOS transistor Q2. The resistor R7 is connected between the negative electrode of the DC power supply DC and the gate of the NMOS transistor Q3. The capacitors C5, C6, and C7 are connected in parallel between the positive and negative electrodes of the lithium battery BT. The negative electrode of the DC power supply DC is grounded.

[0026] The input unit provides power for charging the lithium battery, typically from an adapter, power outlet, or solar energy. It can also forward control commands from the user or other systems, such as charging start, stop, and discharge requests. The lithium battery BT can be a single-cell lithium battery or a unit composed of multiple lithium battery cells. It is responsible for storing electrical energy and providing power to the load when needed. The MCU processor, as the core of the system, is responsible for controlling and managing each module.

[0027] like Figure 2 As shown, the DC power supply DC provides power, its positive electrode connected to the source of the PMOS transistor Q1 through the diode TD1. The drain of the PMOS transistor Q1 is connected to the positive electrode of the lithium battery BT, allowing current to flow into the lithium battery for charging. The gate of the PMOS transistor Q1 is connected to the drain of the NMOS transistor Q2 and receives a control signal from the voltage detection chip GC1 to regulate the charging process. The voltage detection chip GC1 monitors the voltage level of the lithium battery BT in real time to ensure that the charging voltage does not exceed the safety limit. The three connection ports of the voltage detection chip GC1 are the input terminal, the ground terminal, and the output terminal. The input terminal receives the voltage signal from the lithium battery BT, the ground terminal is connected to the negative electrode of the lithium battery BT, and the output terminal provides a monitoring signal of the lithium battery voltage.

[0028] TVS diode TVS1 is connected in parallel between the positive and negative poles of the lithium battery BT, with its positive pole connected to the positive pole of the battery and its negative pole connected to the negative pole of the battery. It is used to absorb transient high energy generated by electrostatic discharge or power surges to protect the circuit from damage; capacitors C5, C6 and C7 are connected in parallel between the positive and negative poles of the lithium battery BT to smooth the voltage fluctuations output by the lithium battery and filter out noise.

[0029] The diode TD1 is used to prevent reverse current flow and protect the circuit from damage. When the PMOS transistor Q1 is in the off state, it blocks current from flowing from the power supply to the battery. When the PMOS transistor Q1 is turned on, current can flow into the lithium battery BT for charging.

[0030] During normal charging, when the voltage detection chip GC1 detects that the lithium battery voltage is below the charging safety threshold, its output terminal outputs a low level. This low-level signal passes through resistor R8 to the gate of NMOS transistor Q3, turning off NMOS transistor Q3. The gate of NMOS transistor Q2 is pulled up by resistor R5 to a high level, turning on NMOS transistor Q2 and pulling down PMOS transistor Q1 to a low level. PMOS transistor Q1 then conducts, allowing current to flow into the lithium battery BT1 through diode TD1 and PMOS transistor Q1. As the lithium battery BT charges, its voltage gradually increases, and the voltage detection chip GC1 monitors this voltage in real time. When the lithium battery BT voltage reaches the charging safety threshold, the voltage detection chip GC1 outputs a high level, turning on NMOS transistor Q3, pulling the gate of NMOS transistor Q2 low, turning off NMOS transistor Q2, and pulling the gate of PMOS transistor Q1 high. PMOS transistor Q1 is turned off, thus cutting off the charging path and completing a charging cycle. Throughout this process, TVS diode TVS1 and capacitors C5, C6, and C7 ensure charging safety and voltage stability of the lithium battery BT.

[0031] The charging protection circuit provided in this application uses the switching action of PMOS and NMOS transistors to cut off the charging power supply when the lithium battery voltage exceeds a preset safety value. In addition, a TVS diode is connected in parallel with the circuit to protect the circuit from transient overvoltage phenomena such as electrostatic discharge (ESD) and power surges.

[0032] Further, such as Figure 3 As shown, the DC-DC converter circuit includes a DC-DC converter, resistors R1, R2, R3, R4, capacitors C1, C2, C3, C4, an inductor L1 and a lithium battery BT. The input terminal VIN of the DC-DC converter is connected to the positive electrode of the lithium battery BT, the negative electrode of the BT is grounded, one end of the capacitors C1, C2, C3, C4, R2 and R4 is grounded, the other ends of the capacitors C1 and C2 are connected to the input terminal VIN of the DC-DC converter, the other end of the resistor R2 is connected to the EN terminal of the DC-DC converter, one end of R1 is connected to the EN terminal of the DC-DC converter, the other ends of the capacitors C3 and C4 are connected to the output terminal VOUT of the DC-DC converter, the other end of the resistor R4 is connected to the FB terminal of the DC-DC converter, one end of the resistor R3 is connected to the FB terminal of the DC-DC converter, and the other end of the resistor R3 is connected to the output terminal VOUT of the DC-DC converter. The inductor L1 is connected between the LX1 pin and the LX2 pin of the DC-DC converter.

[0033] like Figure 3As shown, the DC-DC converter circuit is responsible for converting the output voltage of the lithium battery into an operating voltage suitable for the MCU processor and other loads. Capacitors C1 and C2 are connected in parallel with the lithium battery BT and serve as the DC-DC converter's input filter capacitors. The enable terminal EN is connected to the output terminal of the discharge protection circuit. Under the control of the discharge protection circuit, the enable terminal EN remains high, allowing the DC-DC converter to operate. Inductor L1 is used to store energy and ensure smooth current flow. The output terminal VOUT of the DC-DC converter (VOUT = VFB (R3 / R4 + 1)) is connected to the DC-DC converter's feedback pin FB through voltage-divider resistors R3 and R4. The converter adjusts its operation based on the feedback voltage to maintain a stable output voltage. Capacitors C3 and C4 are connected in parallel in the circuit and serve as the DC-DC converter's output filter capacitors. The negative terminal of the BT, one end of capacitors C1, C2, C3, C4, R2, and R4 are connected to a common ground point GND1, forming a parallel relationship to ensure smooth current return. Through these connections, the DC-DC converter circuit can effectively convert the input voltage into a stable output voltage to meet the load requirements and ensure the safe charging and discharging of the battery.

[0034] The DC-DC converter circuit provided in this application can provide an output voltage that is smaller than or greater than the input voltage to a load.

[0035] Optionally, the DC-DC converter may be a TPS63900DSKR chip.

[0036] Further, such as Figure 4 As shown, the discharge protection circuit includes a lithium battery BT, a voltage detection chip GC2, diodes TD2, TD3, resistors R9, R10, and a capacitor C8. The positive and negative electrodes of the lithium battery BT are respectively connected to the input end and the ground end of the voltage detection chip GC2, the positive electrode of the diode TD3 is connected to the output end of the voltage detection chip GC2, the negative electrode of the diode TD3 is connected to the negative electrode of the diode TD2, one end of the resistor R10 and the capacitor C8 are connected to the negative electrode of the lithium battery BT, the other end of the resistor R10 and the capacitor C8 are connected, one end of the resistor R9 is connected to the negative electrode of the diode TD2, and the other end of the resistor R9 is connected to the resistor R10.

[0037] like Figure 4As shown, the voltage detection chip GC2 monitors the lithium battery voltage and implements dual-path control via the MCU processor pins. When the battery voltage falls below the safe discharge threshold, the discharge path is shut off. The voltage detection chip GC2 has three terminals: input, ground, and output. The input receives the voltage signal from the lithium battery (BT), the ground terminal is connected to the negative terminal of the lithium battery, and the output terminal is connected to the anode of diode TD3. The cathode of diode TD3 is connected to the enable terminal EN of the DC-DC converter through resistors R9 and R1, respectively. This is the first discharge control path. The MCU processor pin POW_EN is connected to the anode of diode TD2, and the cathode of diode TD2 is connected to the enable terminal EN of the DC-DC converter through resistors R9 and R1, respectively. This is the second discharge control path. Resistor R10 is connected in parallel with capacitor C8. One terminal of capacitor C8 is connected between resistor R1 and the enable terminal EN of the DC-DC converter, and the other terminal is connected to the negative terminal of the lithium battery. This stabilizes the voltage on the enable pin and reduces circuit noise.

[0038] During normal discharge, the voltage detection chip GC2 and the MCU jointly monitor the lithium battery voltage. The voltage detection chip GC2 outputs a high level, turning on diode TD3. Simultaneously, the MCU's POW_EN outputs a high level, turning on diode TD2. These two control paths act together on the DC-DC converter enable terminal EN, which first passes through voltage divider resistors R9 and R10, and then through voltage divider resistors R1 and R2 to output a high level, enabling the DC-DC converter. When the lithium battery voltage drops below the discharge safety threshold, the voltage detection chip GC2 outputs a low level, turning off diode TD3. Simultaneously, the MCU also detects the voltage drop, causing POW_EN to output a low level, turning off diode TD2. These two control paths act together on the DC-DC converter enable terminal EN, causing resistor R2 to pull EN down to a low level, ensuring the DC-DC converter is turned off, cutting off the discharge path, and preventing over-discharge of the battery.

[0039] The discharge protection circuit of the present application adopts dual-path control of lithium battery and MCU processor. When the lithium battery voltage is lower than the discharge safety threshold, the MCU processor control pin is forced to output a low level, cutting off the discharge path.

[0040] Furthermore, the model of the voltage detection chip GC1 is BL8506-35CRM, and the model of the voltage detection chip GC2 is BL8506-30CRM.

[0041] The temperature and humidity monitoring module monitors the temperature and ambient humidity of the lithium battery BT in real time and transmits this data to the MCU processor. The MCU processor controls the output of the DC-DC converter according to the load demand and adjusts the charging and discharging strategy based on the feedback from the charging and discharging protection circuit to ensure the safe and efficient operation of the system.

[0042] The load, the system's actual power consumer, draws power from the DC-DC converter circuit. The MCU adjusts power output in real time based on the load's dynamic changes, ensuring the load receives the required power under different operating conditions. Through the coordinated operation of various modules, the entire lithium battery charge and discharge management system achieves efficient and safe battery management, ensuring stable system operation and providing reliable power support for the load.

[0043] In specific implementation, during the charging process, the system first provides a constant charging current to the battery through a charger. At the same time, the charging protection circuit starts working, and the voltage detection circuit and the temperature and humidity monitoring module monitor the charging status of the lithium battery in real time until the battery voltage reaches the preset charging threshold. The charging protection circuit will immediately cut off the charging; the output voltage of the lithium battery energy storage unit is then sent to the DC-DC converter to convert the battery output voltage into an operating voltage suitable for the MCU processor and the load; at the same time, the discharge protection circuit starts working, and the voltage detection circuit and the temperature and humidity monitoring module monitor the discharge status of the lithium battery in real time, and control the discharge path through the MCU processor pin to achieve dual-path control of the lithium battery and the MCU processor; when the battery voltage is lower than the discharge safety threshold, the discharge path will be cut off.

[0044] This application can monitor the working status of lithium batteries in real time and effectively manage the battery's charging and discharging process through charging protection and discharging protection circuits. The electronic devices used in the system design improve the system's response speed and reduce costs by selecting cost-effective domestic chips. The simple design of the system makes the entire system more compact, reduces the number of required chips, improves reliability, and reduces the safety risks caused by battery failure. By precisely controlling the charging and discharging process, this application reduces damage to lithium batteries, extends battery life, reduces user maintenance costs, and achieves low-energy operation.

[0045] The above embodiments are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or substitutions made by those skilled in the art based on the technical features of the present invention fall within the scope of protection of the present invention.

Claims

1. A lithium battery charge and discharge management system, characterized in that: include: An input unit, a DC-DC converter circuit, a charging protection circuit, a discharging protection circuit, a temperature and humidity monitoring module, an MCU processor, and a dynamic load; the input unit is used to provide power, the charging protection circuit is connected to the input unit, the discharging protection circuit is connected to the DC-DC converter circuit, the discharging protection circuit is also connected to the MCU processor, the DC-DC converter circuit is connected to the MCU processor, and the charging protection circuit is connected to the MCU processor; The charging protection circuit is composed of a DC power supply DC, a voltage detection chip GC1, a TVS diode TVS1, a lithium battery BT, a capacitor C5, a capacitor C6, a capacitor C7, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a PMOS transistor Q1, an NMOS transistor Q2, an NMOS transistor Q3 and a diode TD1. The positive electrode of the DC power supply DC is connected to the source of the PMOS transistor Q1 through the diode TD1, the drain of the PMOS transistor Q1 is connected to the positive electrode of the lithium battery BT, the gate of the PMOS transistor Q1 is connected to the drain of the NMOS transistor Q2, the ground terminal of the voltage detection chip GC1 is connected to the negative electrode of the lithium battery BT, the output terminal of the voltage detection chip GC1 is connected to the gate of the NMOS transistor Q3 through the resistor R8, and the NMOS The transistor Q2 and the NMOS transistor Q3 together constitute a dual NMOS structure. The sources of the NMOS transistors Q2 and Q3 are both grounded. The TVS diode TVS1 is connected in parallel between the positive and negative electrodes of the lithium battery BT. The positive electrode of the TVS diode TVS1 is connected to the positive electrode of the lithium battery BT, and the negative electrode of the TVS diode TVS1 is connected to the negative electrode of the lithium battery BT. The resistor R5 is connected between the positive electrode of the input unit DC and the gate of the NMOS transistor Q2. The resistor R6 is connected between the positive electrode of the DC power supply DC and the drain of the NMOS transistor Q2. The resistor R7 is connected between the negative electrode of the DC power supply DC and the gate of the NMOS transistor Q3. The capacitors C5, C6, and C7 are connected in parallel between the positive and negative electrodes of the lithium battery BT. The negative electrode of the DC power supply DC is grounded.

2. A lithium battery charge and discharge management system according to claim 1, characterized in that: The DC-DC converter circuit includes a DC-DC converter, resistors R1, R2, R3, R4, capacitors C1, C2, C3, C4, an inductor L1 and a lithium battery BT. The input terminal VIN of the DC-DC converter is connected to the positive electrode of the lithium battery BT, the negative electrode of the BT is grounded, one end of the capacitors C1, C2, C3, C4, R2 and R4 is grounded, the other ends of the capacitors C1 and C2 are connected to the input terminal VIN of the DC-DC converter, the other end of the resistor R2 is connected to the EN terminal of the DC-DC converter, one end of R1 is connected to the EN terminal of the DC-DC converter, the other ends of the capacitors C3 and C4 are connected to the output terminal VOUT of the DC-DC converter, the other end of the resistor R4 is connected to the FB terminal of the DC-DC converter, one end of the resistor R3 is connected to the FB terminal of the DC-DC converter, and the other end of the resistor R3 is connected to the output terminal VOUT of the DC-DC converter. The inductor L1 is connected between the LX1 pin and the LX2 pin of the DC-DC converter.

3. A lithium battery charge and discharge management system as claimed in claim 2, characterized in that: The discharge protection circuit includes a lithium battery BT, a voltage detection chip GC2, diodes TD2, TD3, resistors R9, R10, and a capacitor C8. The positive and negative electrodes of the lithium battery BT are respectively connected to the input end and the ground end of the voltage detection chip GC2, the positive electrode of the diode TD3 is connected to the output end of the voltage detection chip GC3, the negative electrode of the diode TD3 is connected to the negative electrode of the diode TD2, one end of the resistor R10 and the capacitor C8 are connected to the negative electrode of the lithium battery BT, the other end of the resistor R10 and the capacitor C8 are connected, one end of the resistor R9 is connected to the negative electrode of the diode TD2, and the other end of the resistor R9 is connected to the resistor R10.

4. A lithium battery charge and discharge management system according to any one of claims 1 to 3, characterized in that: The input unit is an adapter, a power socket or solar power supply.

5. A lithium battery charge and discharge management system according to any one of claims 1 to 3, characterized in that: The lithium battery BT is a single-cell lithium battery, or a unit composed of multiple lithium battery cells.

6. A lithium battery charge and discharge management system as claimed in claim 3, characterized in that: The model of the voltage detection chip GC1 is BL8506-35CRM, and the model of the voltage monitoring chip GC2 is BL8506-30CRM.

Images