Intelligent lithium battery charging and discharging circuit

Abstract

The utility model relates to an intelligent lithium battery charging and discharging circuit. The battery is arranged between the charging power supply and the lithium battery; comprising a charging controllable switch, a load controllable switch, a power supply voltage detection circuit, a current limiting circuit, a battery voltage detection circuit and an MCU control unit. The current limiting circuit is located between the positive electrode of the charging power supply and the positive electrode of the lithium battery, the charging controllable switch is located between the charging power supply and the current limiting circuit, the load controllable switch is located between the positive electrode of the lithium battery and the load, the input end of the power supply voltage detection circuit is connected to the positive electrode of the charging power supply, and the output end is connected to the MCU. The input end of the battery voltage detection circuit is connected to the positive electrode of the lithium battery, the output end of the battery voltage detection circuit is connected to the MCU, and the control ends of the charging controllable switch and the load controllable switch are connected to the MCU. The MCU control unit controls on and off of the charging controllable switch and the load controllable switch according to detection voltage values of the power supply voltage detection circuit and the battery voltage detection circuit. According to the utility model, the charging and discharging processes of the lithium battery are intelligently managed, the problems of over-charging and over-discharging are avoided, and the lithium battery is protected.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium battery charging and discharging, and in particular relates to an intelligent lithium battery charging and discharging circuit. Background Art

[0002] With the development of battery technology, lithium batteries have been widely used in an increasing number of electrical products. Lithium batteries have the characteristics of high energy density, small size, and light weight. They are widely used in products ranging from general electronic products to large electric vehicles. For lithium batteries, the key technical content is the management of charge and discharge. A key part of lithium battery charge and discharge management is to prevent the battery from overcharging and over-discharging. Overcharging causes internal pressure to increase, which may cause the battery to swell, heat up, or even explode. Overcharging generates excessive heat and gas, causing the battery casing to deform or rupture due to unbearable conditions. Overdischarging can disrupt the battery's chemical balance, damage the active materials in the positive and negative electrodes, decompose the electrolyte, deposit lithium on the negative electrode, and increase the battery's internal resistance. The aforementioned damage is usually irreversible. Even after recharging, the battery capacity will be significantly reduced or even unusable.

[0003] In summary, it is necessary to develop and design a charge and discharge management circuit for lithium batteries to intelligently manage the charge and discharge process of lithium batteries, avoid overcharging and over-discharging problems, and provide protection for lithium batteries. Utility Model Content

[0004] The purpose of the utility model is to provide an intelligent lithium battery charging and discharging circuit, which can intelligently manage the charging and discharging process of the lithium battery, avoid overcharging and overdischarging problems, and provide protection for the lithium battery.

[0005] The technical solution adopted by the utility model is: an intelligent lithium battery charging and discharging circuit, located between a charging power supply and a lithium battery; including a charging controllable switch and a load controllable switch, and also including a power supply voltage detection circuit, a current limiting circuit and a battery voltage detection circuit and an MCU control unit; the current limiting circuit is located between the positive pole of the charging power supply and the positive pole of the lithium battery, the charging controllable switch is located between the charging power supply and the current limiting circuit, the load controllable switch is located between the positive pole of the lithium battery and the load, the input end of the power supply voltage detection circuit is connected to the positive pole of the charging power supply, and the output end is connected to the MCU control unit, the input end of the battery voltage detection circuit is connected to the positive pole of the lithium battery, and the output end is connected to the MCU control unit, the control ends of both the charging controllable switch and the load controllable switch are connected to the MCU control unit, and the MCU control unit controls the opening and closing of the charging controllable switch and the load controllable switch according to the detection voltage values ​​of the power supply voltage detection circuit and the battery voltage detection circuit.

[0006] Preferably, the power supply voltage detection circuit is a main power supply voltage divider circuit composed of resistors R5, R6, R13 and capacitor C1, which provides the voltage value required for AD detection of the MCU control unit. When the power supply voltage is normal, the voltage after resistor division is 2.36V.

[0007] Preferably, the current limiting circuit includes a current limiting circuit composed of three current limiting resistors, namely, resistor R77, resistor R78, and resistor R79, connected in parallel, to limit the maximum charging current to 960 mA.

[0008] Preferably, the battery voltage detection circuit is a backup power supply voltage divider circuit composed of resistors R8, R17, R14 and capacitor C3, which provides the voltage value required for AD detection of the MCU control unit. When the battery is fully charged, the voltage after resistor division is 2.32V.

[0009] Preferably, the charge controllable switch V3 is selected as a high-power MOS tube, and the MCU control unit controls the connection and disconnection of the MOS tube in various stages of charging; the load controllable switch V2 is a high-power MOS tube, and the MCU control unit controls the connection and disconnection of the MOS tube in various stages of discharging.

[0010] The advantages and positive effects of the utility model are:

[0011] The utility model provides an intelligent lithium battery charging and discharging circuit. By providing a power supply voltage detection circuit and a battery voltage detection circuit, voltage detection of the charging power supply and the lithium battery is achieved. By providing a charge-controlled switch and having the charge-controlled switch be switched on and off by an MCU control unit, the technical effect of disconnecting the charging path when the lithium battery is detected to have reached the charge cut-off voltage during the charging process is achieved to avoid overcharging. By providing a load-controlled switch and having the load-controlled switch be switched on and off by an MCU control unit, the technical effect of disconnecting the power path when the lithium battery is detected to have reached the discharge cut-off voltage during the discharge process is achieved to avoid over-discharge. By providing a current limiting circuit, a current limiting effect on the charging current is achieved during the charging process, achieving the technical effect of limiting the charging current.

[0012] Therefore, the intelligent lithium battery charging and discharging circuit of the present invention controls the charging controllable switch and the opening and closing of the charging controllable switch based on the detection voltage values ​​detected by the power supply voltage detection circuit and the battery voltage detection circuit received by the MCU control unit, thereby realizing intelligent and effective management of the charging and discharging processes of the lithium battery, avoiding the problems of overcharging and over-discharging of the lithium battery, and providing protection for the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural diagram of the utility model;

[0014] Figure 2It is a circuit diagram of a specific embodiment of the utility model. DETAILED DESCRIPTION

[0015] In order to further understand the content, features and effects of the present invention, the following embodiments are given to illustrate in detail.

[0016] See Figure 1 This intelligent lithium battery charging and discharging circuit is located between the charging power supply and the lithium battery, effectively managing the charging and discharging processes of the lithium battery. The charging power supply voltage depends on the lithium battery's charge cutoff voltage and can be set according to the lithium battery's voltage specifications.

[0017] The intelligent lithium battery charging and discharging circuit includes a charge-controlled switch and a load-controlled switch, as well as a power supply voltage detection circuit, a current limiting circuit, a battery voltage detection circuit, and an MCU control unit. The charge-controlled switch determines whether the charging circuit is on or off, while the load-controlled switch determines whether the discharge circuit (i.e., the load power circuit) is on or off. The power supply voltage detection circuit is used to detect the voltage of the charging power supply and determine whether the charging power supply is functioning properly by detecting the voltage of the charging power supply. The battery voltage detection circuit is used to detect the voltage of the lithium battery, including the charging cut-off voltage and the discharging cut-off voltage. The detected lithium battery voltage value serves as the basis for the MCU control unit to control the operation of the charge-controlled switch and the load-controlled switch.

[0018] The current limiting circuit is located between the positive electrode of the charging power supply and the positive electrode of the lithium battery, and is used to limit the charging current. The charging controllable switch is located between the charging power supply and the current limiting circuit. During the charging process, the charging controllable switch is closed to connect the charging circuit. After the lithium battery reaches the charging cut-off voltage, the charging controllable switch is turned off to disconnect the charging circuit to prevent overcharging. The load controllable switch is located between the positive electrode of the lithium battery and the load. During the discharge process, the load controllable switch is closed to connect the discharge circuit (that is, the power circuit), allowing the load to use electricity normally. After the lithium battery reaches the discharge cut-off voltage, the load controllable switch is turned off to disconnect the discharge circuit to prevent overdischarge.

[0019] The power supply voltage detection circuit has an input connected to the positive electrode of the charging power supply and an output connected to the MCU control unit. The voltage value detected by the power supply voltage detection circuit is sent to the MCU control unit, which uses this voltage value to determine whether the charging power supply is in normal condition. The charging process will only start when the charging power supply is in normal condition. The battery voltage detection circuit has an input connected to the positive electrode of the lithium battery and an output connected to the MCU control unit. The battery voltage detection circuit detects and sends the voltage value to the MCU control unit, which determines the status of the lithium battery based on the voltage and controls the charge controllable switch and the load controllable switch based on this determination. The control terminals of both the charge controllable switch and the load controllable switch are connected to the MCU control unit, and the MCU control unit controls the opening and closing of the charge controllable switch and the load controllable switch based on the voltage values ​​detected by the power supply voltage detection circuit and the battery voltage detection circuit.

[0020] Figure 2 This is the circuit diagram, combined with the attached Figure 2 A specific embodiment is given to illustrate the technical solution of the lithium battery charging and discharging circuit. In this embodiment, the rated voltage specification of the lithium battery is set to 24V, the charging cut-off voltage is 25.2V, and the discharging cut-off voltage is 16.5V.

[0021] In this embodiment, the power supply voltage detection circuit is a main power supply voltage divider circuit composed of resistors R5, R6, and R13, and capacitor C1. It provides the voltage required for AD detection by the MCU control unit. When the power supply voltage is normal, the resistor-divided voltage is 2.36V. The MCU control unit calculates the power supply voltage based on this voltage value to determine whether the power supply voltage is normal.

[0022] In this embodiment, the current limiting circuit includes a current limiting circuit composed of three current limiting resistors, namely, resistor R77, resistor R78, and resistor R79, connected in parallel, which limits the maximum charging current to 960 mA.

[0023] In this embodiment, the battery voltage detection circuit is a backup power supply voltage divider circuit composed of resistors R8, R17, and R14, and capacitor C3. This circuit provides the voltage required for AD detection by the MCU control unit. When the battery is fully charged, the resistor-divided voltage is 2.32V. The MCU control unit calculates the battery voltage based on this voltage value to determine whether the battery voltage is normal.

[0024] In this embodiment, the charge controllable switch V3 is selected as a high-power MOS tube, and the MCU control unit controls the connection and disconnection of the MOS tube in various stages of charging; the load controllable switch V2 is a high-power MOS tube, and the MCU control unit controls the connection and disconnection of the MOS tube in various stages of discharging.

[0025] Working process:

[0026] (1) Charging process: When the charging power is turned on, the MCU control unit detects the presence of charging voltage through the power supply voltage detection circuit and detects that the lithium battery voltage is between 16.5 and 24V through the battery voltage detection circuit, the charging controllable switch is turned on for charging, and the charging current is limited to about 1A by the current limiting circuit; when the MCU control unit detects that the lithium battery voltage reaches 25.2V, the charging controllable switch is turned off to prevent overcharging, and charging is completed.

[0027] (2) Discharge process: The lithium battery is discharged through the load. When the MCU control unit detects that the voltage of the lithium battery is lower than 17.5V through the battery voltage detection circuit, it cuts off the load controllable switch and disconnects the lithium battery from the load to prevent the lithium battery from over-discharging. The discharge is completed.

[0028] (3) If the MCU control unit detects that the battery voltage is 0V through the battery voltage detection circuit after the charging power is turned on, it indicates that the lithium battery does not exist or the lithium battery is damaged. In this case, the charging controllable switch is cut off and the charging process is not carried out.

Claims

1. An intelligent lithium battery charging and discharging circuit, located between a charging power source and a lithium battery; characterized by: It includes a charging controllable switch and a load controllable switch, as well as a power supply voltage detection circuit, a current limiting circuit, a battery voltage detection circuit and an MCU control unit; the current limiting circuit is located between the positive pole of the charging power supply and the positive pole of the lithium battery, the charging controllable switch is located between the charging power supply and the current limiting circuit, the load controllable switch is located between the positive pole of the lithium battery and the load, the input end of the power supply voltage detection circuit is connected to the positive pole of the charging power supply, and the output end is connected to the MCU control unit, the input end of the battery voltage detection circuit is connected to the positive pole of the lithium battery, and the output end is connected to the MCU control unit, the control ends of both the charging controllable switch and the load controllable switch are connected to the MCU control unit, and the MCU control unit controls the opening and closing of the charging controllable switch and the load controllable switch according to the detection voltage values ​​of the power supply voltage detection circuit and the battery voltage detection circuit.

2. The intelligent lithium battery charging and discharging circuit according to claim 1, wherein: The power supply voltage detection circuit is a main power supply voltage divider circuit composed of resistors R5, R6, R13 and capacitor C1, which provides the voltage value required for AD detection of the MCU control unit. When the power supply voltage is normal, the resistor voltage is 2.36V after voltage division.

3. The intelligent lithium battery charging and discharging circuit according to claim 2, wherein: The current limiting circuit includes a current limiting circuit composed of three current limiting resistors R77, R78 and R79 connected in parallel, which limits the maximum charging current to 960mA.

4. The intelligent lithium battery charging and discharging circuit according to claim 3, wherein: The battery voltage detection circuit is a backup power supply voltage divider circuit composed of resistors R8, R17, R14 and capacitor C3, which provides the voltage value required for AD detection of the MCU control unit. When the battery is fully charged, the resistor voltage is 2.32V after voltage division.

5. The intelligent lithium battery charging and discharging circuit according to claim 4, wherein: The charge controllable switch V3 is selected as a high-power MOS tube, and the MCU control unit controls the connection and disconnection of the MOS tube in various stages of charging; the load controllable switch V2 is a high-power MOS tube, and the MCU control unit controls the connection and disconnection of the MOS tube in various stages of discharging.

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