A lithium battery pack charging equalization circuit and a charging equalization method

Abstract

The application discloses a lithium battery pack charging equalization circuit and a charging equalization method, which are composed of a lithium battery pack formed by connecting two or more lithium batteries in series, a main control module, a voltage acquisition module, a main charging loop, an auxiliary charging loop and a charging switching module. The voltage acquisition module is connected with the lithium battery pack, the data output end of the voltage acquisition module is connected with the main control module, the main charging loop and the auxiliary charging loop are respectively connected with the charging switching module, and the charging switching module is connected with the main control module. The main charging loop is used for charging the whole series-connected lithium battery pack, and the auxiliary charging loop is used for separately charging a single lithium battery. The application proposes a novel charging equalization circuit, the whole charging and single battery charging are switched by using the charging switching module, the voltage of the battery pack can be efficiently equalized, and the charging efficiency and the equalization of the lithium battery pack charging can be ensured.

Description

Technical Field

[0001] This invention discloses a lithium battery pack charging circuit, and more particularly a lithium battery pack charging equalization circuit and charging equalization method, belonging to the field of new energy application technology. Background Technology

[0002] With the rapid development of the new energy industry, lithium batteries, with their advantages of high energy density and long cycle life, have been widely used in various fields such as new energy vehicles, energy storage power stations, and portable electronic devices. In practical applications, to meet the voltage and capacity requirements of different scenarios, lithium batteries are usually used in the form of modules, that is, multiple cells are connected in series to form a lithium battery pack. During charging, lithium-ion batteries require voltage control to prevent overcharging and ensure safety. However, when charging multiple battery cells in a series, all cells operate on the same current circuit, making it impossible to control the voltage of each cell in a single series. Overcharging is prevented by detecting the total voltage or cutting off the overall charging circuit when each cell reaches its upper limit. Differences in lithium battery consistency lead to voltage variations, resulting in different states of charge and reduced battery life. To address this, passive voltage balancing using resistor discharge is commonly used. However, this method is inefficient and generates significant heat, negatively impacting battery pack temperature management and potentially causing safety issues. Summary of the Invention

[0003] To address the problem mentioned above that it is difficult to achieve balanced charging of each battery in the existing lithium battery pack, this invention provides a new lithium battery pack charging balancing circuit and charging balancing method. It uses a charging switching module to control the switching between overall charging and individual battery charging, thereby ensuring both charging efficiency and balanced charging of the lithium battery pack.

[0004] The technical solution adopted by this invention to solve its technical problem is: a lithium battery pack charging equalization circuit, which is used to charge a battery pack consisting of two or more lithium batteries connected in series. The charging equalization circuit includes a lithium battery pack consisting of two or more lithium batteries connected in series, a main control module, a voltage acquisition module, a main charging circuit, an auxiliary charging circuit, and a charging switching module. The voltage acquisition module is connected to the lithium battery pack, and the data output terminal of the voltage acquisition module is connected to the main control module. The main charging circuit and the auxiliary charging circuit are respectively connected to the charging switching module, and the charging switching module is connected to the main control module. The main charging circuit is used to charge the entire series-connected lithium battery pack, and the auxiliary charging circuit is used to charge a single lithium battery individually.

[0005] A charging equalization method, the method comprising the following steps: Step S1: Charge the battery pack using a power supply or charger. At the same time, the voltage sampling module samples the voltage in real time. Step S2: When the voltage of one or more batteries in the battery pack reaches the set voltage threshold, the main control module controls the main charging control module to shut down the main charging circuit. Step S3: The main control module controls the charging switching module to intelligently switch to the auxiliary charging circuit to charge individual batteries in the battery pack. Step S4: When all battery voltages reach the voltage threshold and cutoff current, turn off the auxiliary charging circuit. Step S5: Turn off the charging circuit. Charging is complete.

[0006] The technical solution adopted by the present invention to solve its technical problem further includes: The auxiliary charging circuit consists of two or more auxiliary charging modules. Each auxiliary charging module has the same circuit structure and connection method. Each auxiliary charging module includes a power controller U211, an inductor L1, and a battery charging management chip U212. The power input terminal of the power controller U211 is connected to the auxiliary charging interface of the charging control module. The ground terminal of the power controller U211 is connected to the negative input interface C-. The first and second pins of the inductor L1 are connected between the auxiliary input DC power supply VIN and the SW pin of the power controller U211. The third and fourth pins of the inductor L1 are connected to the battery charging management chip U212. The BAT pin of the battery charging management chip U212 is connected to the positive terminal of the battery B1.

[0007] The charging switching module includes transistor Q1, PMOS transistor QCA, and PMOS transistor QCB. The base of transistor Q1 is connected to the control pin of the main control module, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the gate of PMOS transistors QCA and QCB through a resistor, the drain of PMOS transistors QCA and QCB is connected, the source of PMOS transistor QCA is connected to the positive input terminal BN, and the source of PMOS transistor QCB is connected to the auxiliary input DC power supply VIN.

[0008] The main charging circuit adopts a main charging control module, which uses an NMOS transistor QC. The gate of the NMOS transistor QC is connected to a control pin of the main control module through a resistor. The source of the NMOS transistor QC is the input negative terminal C- interface. A Zener diode ZD2 is connected in parallel between the gate and the source of the NMOS transistor QC.

[0009] The voltage acquisition module uses one or more voltage acquisition chips, which are connected in a cascaded or independent manner. The signal output terminal of each voltage acquisition chip is directly or indirectly connected to the data terminal of the main control module. Each voltage acquisition chip acquires the voltage of one or more individual lithium batteries.

[0010] One or more of the voltage acquisition chips are connected to a temperature detection module. The temperature detection module includes a voltage divider resistor R54, a thermistor NTC1, a voltage divider resistor R56, a voltage divider resistor R53, a thermistor NTC2, and a voltage divider resistor R55. The voltage divider resistors R54, NTC1, and R56 are connected in series between the REG50 interface and GND of the voltage acquisition chip U1. The common terminal of the thermistor NTC1 and the voltage divider resistor R56 is connected to the TS2+ interface of the voltage acquisition chip U1. The voltage divider resistors R53, NTC2, and R55 are connected in series between the REG50 interface and GND of the voltage acquisition chip U1. The common terminal of the thermistor NTC2 and the voltage divider resistor R55 is connected to the TS1+ interface of the voltage acquisition chip U1.

[0011] The main control module is connected to an LCD display interface (LCD) on its data terminal, and / or an LED is connected to the data terminal of the main control module.

[0012] The main control module has a wired communication interface connected to its data terminal, and / or a wireless communication interface connected to its data terminal.

[0013] The main control module is connected to a positioning interface module, which includes a transistor Q2 and a positioning interface GPS. The base of transistor Q2 is connected to the control pin (PC7) of the main control module, the emitter of transistor Q2 is grounded, and the collector of transistor Q2 is connected to the positioning interface GPS.

[0014] The main control module is connected to a low-voltage switch S2.

[0015] The beneficial effects of this invention are: This invention proposes a brand-new charging equalization circuit, which uses a charging switching module to control the switching between overall charging and individual battery charging, which can efficiently balance the voltage of the battery pack. It is simple and easy to implement, which can ensure charging efficiency and balanced charging of lithium battery pack, minimize damage to battery life, and improve safety in use.

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Figure 1 This is a circuit block diagram of the present invention.

[0018] Figure 2 This is a circuit diagram of the main control module (including the reset switch) in this invention.

[0019] Figure 3 This is a schematic diagram of the battery voltage acquisition and battery pack circuit in this invention.

[0020] Figure 4 This is a partial circuit diagram of the first battery voltage acquisition module in this invention.

[0021] Figure 5 This is a circuit diagram of the last battery voltage acquisition module in this invention.

[0022] Figure 6 This is a circuit diagram of the single battery connection part in this invention.

[0023] Figure 7 This is a circuit diagram of the auxiliary charging module in this invention.

[0024] Figure 8 This is a partial circuit diagram of a single auxiliary charging module in this invention.

[0025] Figure 9 This is a partial circuit diagram of the main charging control module and the discharging control module in this invention.

[0026] Figure 10 This is a circuit diagram of the charging switching module in this invention.

[0027] Figure 11 This is a circuit diagram of the step-down module in this invention.

[0028] Figure 12 This is a circuit diagram of the power supply module in this invention.

[0029] Figure 13 This is a circuit diagram of the reference voltage module in this invention.

[0030] Figure 14 This is a circuit diagram of the positioning interface module in this invention.

[0031] Figure 15 This is a circuit diagram of the LCD display interface module in this invention.

[0032] Figure 16 This is a circuit schematic diagram of the wired communication interface module in this invention.

[0033] Figure 17 This is a circuit schematic diagram of the wireless communication interface module in this invention.

[0034] Figure 18This is a circuit schematic diagram of the simulation debugging interface module in this invention.

[0035] Figure 19 This is a circuit diagram of the power display module in this invention.

[0036] Figure 20 This is a circuit schematic diagram of the data storage module in this invention.

[0037] Figure 21 This is a circuit diagram of the low-voltage switch section in this invention.

[0038] Figure 22 This is a circuit diagram of the temperature detection module in this invention.

[0039] Figure 23 This is a circuit diagram of the low-temperature heating module in this invention.

[0040] Figure 24 This is a flowchart of the balancing method in this invention. Detailed Implementation

[0041] This embodiment is a preferred embodiment of the present invention. All other embodiments that are the same as or similar to this embodiment in principle and basic structure are within the protection scope of the present invention.

[0042] Please refer to the appendix for details. Figure 1 To be continued Figure 23 This invention primarily protects a lithium battery pack charging equalization circuit. This circuit is used to charge a battery pack consisting of two or more lithium batteries connected in series. It comprises a lithium battery pack consisting of n (n≥2) lithium batteries connected in series, a main control module, a voltage acquisition module, a main charging circuit, an auxiliary charging circuit, and a charging switching module. The voltage acquisition module is connected to the lithium battery pack and is used to acquire the voltage of the lithium battery pack. The data output terminal of the voltage acquisition module is connected to the main control module and outputs the acquired voltage information to the main control module. The main charging circuit and the auxiliary charging circuit are respectively connected to the charging switching module. The charging switching module controls whether the main charging circuit or the auxiliary charging circuit charges the battery pack. The charging switching module is connected to the main control module and the main control module controls the charging switching module to switch charging modes. The main charging circuit is used to charge the entire series-connected lithium battery pack, and the auxiliary charging circuit is used to charge each individual lithium battery separately.

[0043] In this embodiment, the lithium battery pack consists of n lithium batteries connected in series, which are respectively defined as lithium battery B1, lithium battery B2 to lithium battery Bn.

[0044] In this embodiment, the voltage conversion and protection modules that supply power to the entire invention via the input positive electrode BN and the input negative electrode C- can be commonly used lithium battery pack power supply modules in the prior art.

[0045] In this embodiment, the main control module can be a microcontroller U3. A reset switch S1 is connected to the NRST interface of the microcontroller U3, which can perform manual forced reset. A crystal oscillator Y1 is connected to the OSC_IN interface and the OSC_OUT interface of the microcontroller U3.

[0046] In this embodiment, the voltage acquisition module is implemented using a dedicated voltage acquisition chip. A single chip can simultaneously acquire voltage information from six groups of lithium batteries and can be cascaded. In this invention, m voltage acquisition chips are used, the specific number depending on the number of batteries in the lithium battery pack, but at least one chip. Please refer to the appendix for details. Figure 4 and attached Figure 5 , attached Figure 4 and attached Figure 5The diagram illustrates the connection methods of the first and last voltage acquisition chips in this invention. Several more voltage acquisition chips can be connected between the first and last chips. The CS_H, SDI_H, SDO_H, SCLK_H, FAULT_H, DRDY_H, and CONV_H pins of the first voltage acquisition chip U1 are connected to the data terminal of the main control module, transmitting the acquired voltage information to the main control module. The CS_H, SDI_H, SDO_H, SCLK_H, FAULT_H, DRDY_H, and CONV_H pins of the other voltage acquisition chips are all left floating. The CS_S, SDI_S, SDO_S, SCLK_S, FAULT_S, DRDY_S, and CONV_S pins of voltage acquisition chip U1 are grounded. The CS_S, SDI_S, SDO_S, SCLK_S, FAULT_S, DRDY_S, and CONV_S pins of the other voltage acquisition chips are grounded. The CS_S, SCLK_S, FAULT_S, DRDY_S, and CONV_S pins are respectively connected to the CS_N, SDI_N, SDO_N, SCLK_N, FAULT_N, DRDY_N, and CONV_N pins of the previous voltage acquisition chip. The CS_N, SDI_N, SDO_N, SCLK_N, FAULT_N, DRDY_N, and CONV_N pins of voltage acquisition chip U1 are then connected to the CS_S, SDI_S, SDO_S, SCLK_N, FAULT_N, DRDY_N, and CONV_N pins of the next voltage acquisition chip (voltage acquisition chip U2), and so on, forming a cascaded configuration until voltage acquisition chip UN / 6. The CS_N, SDI_S, SDO_S, SCLK_N, FAULT_N, DRDY_S, and CONV_S pins of the last voltage acquisition chip UN / 6 are connected to the next voltage acquisition chip. The _N, SDO_N, SCLK_N, FAULT_N, DRDY_N, and CONV_N pins are connected to the positive input terminal (BN in this embodiment). The VC1 pin of voltage acquisition chip U1 is connected to the positive terminal of lithium battery B1 through a series-connected current-limiting resistor R14, and is grounded through a filter capacitor C6. The VC2 pin of voltage acquisition chip U1 is connected to the positive terminal of lithium battery B2 through a series-connected current-limiting resistor R13, and is grounded through a filter capacitor C5. The VC3 pin of voltage acquisition chip U1 is connected to the positive terminal of lithium battery B3 through a series-connected current-limiting resistor R12, and is grounded through a filter capacitor C4. The VC4 pin of voltage acquisition chip U1 is connected to the positive terminal of lithium battery B4 through a series-connected current-limiting resistor R11, and is grounded through a filter capacitor C3.The VC5 pin of voltage acquisition chip U1 is connected to the positive terminal of lithium battery B5 through a series current-limiting resistor R10. The VC5 pin of voltage acquisition chip U1 is grounded through filter capacitor C2. The VC6 pin of voltage acquisition chip U1 is connected to the positive terminal of lithium battery B6 through a series current-limiting resistor R9. The VC6 pin of voltage acquisition chip U1 is grounded through filter capacitor C1. The connection methods of other voltage acquisition chips and lithium batteries in the battery pack are similar. The VSS6, VREF, LDOA, LDOD1, and LDOD2 pins of voltage acquisition chip U1 are grounded. The VSS6, VREF, LDOA, LDOD1, and LDOD2 pins of other voltage acquisition chips are connected to the positive terminal of the last lithium battery sampled by the previous chip. Specifically, the VSS6, VREF, LDOA, LDOD1, and LDOD2 pins of voltage acquisition chip U2 are connected to the positive terminal of battery B6; the VSS6, VREF, LDOA, LDOD1, and LDOD2 pins of voltage acquisition chip U3 are connected to the positive terminal of battery B12, and so on, until the last voltage acquisition chip UN / 6 has its VSS6, VREF, LDOA, LDOD1, and LDOD2 pins connected to the positive terminal of battery BN-6.

[0047] In this embodiment, a temperature detection module is connected to the voltage acquisition chip U1. The temperature detection module includes a voltage divider resistor R54, a thermistor NTC1, a voltage divider resistor R56, a voltage divider resistor R53, a thermistor NTC2, and a voltage divider resistor R55. The voltage divider resistors R54, NTC1, and R56 are connected in series between the REG50 interface and GND of the voltage acquisition chip U1. The common terminal of the thermistor NTC1 and the voltage divider resistor R56 is connected to the TS2+ interface of the voltage acquisition chip U1. The voltage divider resistors R53, NTC2, and R55 are connected in series between the REG50 interface and GND of the voltage acquisition chip U1. The common terminal of the thermistor NTC2 and the voltage divider resistor R55 is connected to the TS1+ interface of the voltage acquisition chip U1.

[0048] In this embodiment, the auxiliary charging circuit, also known as the charging balance circuit, consists of two or more sets of auxiliary charging modules. Theoretically, one set of auxiliary charging modules is set for each group of lithium batteries, meaning the number of auxiliary charging modules is the same as the number of batteries in the battery pack. Since the circuit structure and connection method of each auxiliary charging module are the same, the first set is used as an example below, and the structure of the other auxiliary charging modules can be referenced from the structure of the first set of auxiliary charging modules. The first set of auxiliary charging modules adopts a combination circuit of isolated flyback switching power supply + battery charging management. Its main function is to convert the auxiliary input DC power supply (VIN) into an isolated DC voltage and then charge the lithium battery B1. The first set of auxiliary charging modules includes a power controller U211, an inductor L1, and a battery charging management chip U212. The power input terminal (i.e., the VIN interface) of the power controller U211 is connected to the auxiliary charging interface of the charging control module, and the ground terminal (i.e., GND) of the power controller U211 is connected to the negative input interface C-. A filter capacitor is connected in parallel between the VIN interface and the GND interface of the power controller U211. C25 and filter capacitor C26 are input filter capacitors used to filter out ripple in the input voltage. Resistors R58 and R57 are connected in series between the VIN and GND interfaces of the power controller U211. The voltage divider circuit formed by resistors R58 and R57 provides the enable voltage to the EN / UVLO pin of the power controller U211. When the negative input interface C- is low, the EN / UVLO pin receives sufficient voltage, and the power controller U211 starts working; when the negative input interface C- is high, the power controller U211 shuts down, and the entire power supply stops working.

[0049] The SW pin of the power controller U211 drives the internal power transistor, generating a high-frequency square wave pulse to drive the first and second pins (i.e., the primary side) of inductor L1. A Zener diode Z1 and a diode D1 are connected in series between the VIN interface and the SW pin of the power controller U211. A capacitor C30 is connected in parallel with the Zener diode Z1. Capacitor C30, Zener diode Z1, and diode D1 constitute a clamping protection circuit for the primary side, used to absorb the voltage spikes generated by the leakage inductance of inductor L1 and prevent the power controller U211 from being damaged. A resistor R59 is connected between the SW pin and the RFB pin of the power controller U211. The voltage of the primary winding is sampled through resistor R59 to achieve voltage regulation control, eliminating the need for optocoupler feedback and simplifying the circuit design.

[0050] The first and second pins of inductor L1 are connected between the auxiliary input DC power supply VIN and the SW pin of the power controller U211. Inductor L1 provides electrical isolation and voltage conversion, allowing the high-frequency square wave energy from the primary winding to be transferred to the secondary winding via magnetic coupling. The fourth pin of inductor L1 is grounded, and a diode D2 is connected in series with the third pin. Diode D2 rectifies the high-frequency pulse voltage of the secondary winding into unidirectional pulsating DC. Capacitors C27, C28, C29, and C31 are connected in parallel between the third and fourth pins of inductor L1. These capacitors act as output filter capacitors, smoothing the rectified voltage to obtain a stable DC output. A resistor R60 is connected between the third and fourth pins of inductor L1, acting as a dummy load resistor to maintain a stable output voltage under no-load conditions and prevent voltage drift.

[0051] The output of diode D2 is connected to the VCC interface of battery charging management chip U212 to power the chip. The PROG interface of battery charging management chip U212 is grounded through resistor R61, and the charging current is set through resistor R61. The BAT pin of battery charging management chip U212 is connected to the positive terminal of battery B1 to provide charging current to battery B1. A capacitor C32 is connected between the BAT pin of battery charging management chip U212 and ground. Capacitor C32 is a battery-side filter capacitor that can filter out the ripple at the output of battery charging management chip U212.

[0052] The first auxiliary charging module can charge the lithium battery B1 independently, and other auxiliary charging modules can also charge other lithium batteries independently.

[0053] In this embodiment, the charging switching module is used to control whether to switch between the main charging circuit and the auxiliary charging circuit to charge the lithium battery pack. The charging switching module adopts a bidirectional switching structure composed of PMOS transistors, mainly including transistor Q1, PMOS transistor QCA, and PMOS transistor QCB. The base of transistor Q1 is connected to the control pin of the main control module (in this embodiment, it is the PC14 interface of the microcontroller U3, which acts as CHFON and serves to output control signals; it is defined as the control pin in this invention) through resistor R145. The emitter of transistor Q1 is grounded, and the collector of transistor Q1 is connected to the gates of PMOS transistors QCA and QCB through resistor R144. Resistor R146 is connected between the base and emitter of transistor Q1. QCA and PMOS transistor QCB are connected in reverse parallel, meaning their drains are connected. The source of PMOS transistor QCA is connected to the positive input terminal BN, and the source of PMOS transistor QCB is connected to the auxiliary input DC power supply VIN to provide power to each auxiliary charging module. A resistor R142 is connected between the source and gate of PMOS transistor QCA, and a resistor R143 is connected between the source and gate of PMOS transistor QCB. Resistors R142 and R143 provide a voltage divider for the gate, ensuring reliable turn-on or turn-off of the PMOS transistors. When CHGON is high, transistor Q1 is turned on, and the gates of PMOS transistors QCA and QCB are pulled close to ground. At this time, the positive input BN provides power to the auxiliary input DC power supply VIN through PMOS transistors QCA and QCB, switching to auxiliary power supply mode, that is, charging individual lithium batteries through each auxiliary charging module. Conversely, when CHGON is low, transistor Q1 is not turned on, and the positive input BN does not provide power to the auxiliary input DC power supply VIN. Instead, the entire lithium battery pack is charged through the positive input BN.

[0054] In this embodiment, a main charging control module is also connected to the main control module. The main charging control module mainly uses an NMOS transistor QC. The gate of the NMOS transistor QC is connected to a control pin of the main control module (in this embodiment, it is the PC0 interface of the microcontroller U3, which is used to output control signals; it is defined as the control pin in this invention) through a current-limiting resistor R140. The source of the NMOS transistor QC is the negative input C- interface. A Zener diode ZD2 and a resistor R141 are connected in parallel between the gate and the source of the NMOS transistor QC. The Zener diode ZD2 is used to clamp the gate voltage of the NMOS transistor QC to prevent the NMOS transistor QC from being broken down by high voltage. The gate potential (CO) of the NMOS transistor QC is directly connected to a control pin (PC0) of the main control module through a resistor R140. When the data terminal of the main control module outputs a high level, the NMOS transistor QC is turned on; when the data terminal of the main control module outputs a low level, the NMOS transistor QC is turned off.

[0055] In this embodiment, the data terminals (PB8 and PB9) of the main control module are connected to an LCD display interface (LCD), and an LCD screen can be connected to the LCD display interface (LCD) to display the status information of the present invention.

[0056] In this embodiment, each of the data terminals (PB12, PB13, PB14, PB15 and PC6) of the main control module is connected to an LED, namely LED1, LED2, LED3, LED4 and LED5. The main control module directly drives LED1, LED2, LED3, LED4 and LED5 to light up, which serves as a power display module to display the power of the battery pack, so that users can clearly know how much power is left in the battery.

[0057] In this embodiment, the main control module's data terminals (PA11 and PA12) are connected to a CAN interface J1, which can be used to connect to a CAN controller for CAN communication. As a wired communication interface, it is used to communicate with external devices and transmit relevant information about the battery pack to the external devices. In specific implementations, an RS-485 interface can also be used as a wired communication interface.

[0058] In this embodiment, the main control module's data terminals (PC10 and PC11) are connected to a Bluetooth interface J2, which can be used to connect to a Bluetooth controller for Bluetooth communication with clients (mobile phones, computers, etc.) as a wireless communication interface, so that users can intuitively understand and modify the relevant parameters of the battery pack. In specific implementations, a WiFi interface can also be used as a wireless communication interface.

[0059] In this embodiment, a positioning interface module is connected to the control pin of the main control module (in this embodiment, it is the PC7 interface of the microcontroller U3, which serves to output control signals; it is defined as the control pin in this invention). The positioning interface module includes a transistor Q2 and a positioning interface GPS. The base of transistor Q2 is connected to the data terminal (PC7) of the main control module through a current-limiting resistor R154. The emitter of transistor Q2 is grounded, and the collector of transistor Q2 is connected to the positioning interface GPS. A GPS module can be connected to the positioning interface GPS to locate the battery pack of this invention and prevent the battery pack from being lost or stolen. In specific implementation, Beidou or other positioning chips can also be used as the positioning module.

[0060] In this embodiment, a low-temperature heating module is connected to the control pin of the main control module (in this embodiment, it is the PC8 interface of the microcontroller U3, which is used to output control signals; it is defined as the control pin in this invention). The low-temperature heating module includes a transistor Q5 and a heating wire interface R. The base of transistor Q5 is connected to the data terminal (PC8) of the main control module through a current-limiting resistor R160. The emitter of transistor Q5 is grounded, and the collector of transistor Q5 is connected to the heating wire interface R. A heating wire can be connected to the heating wire interface R. The low-temperature heating module can solve the problem of heating the battery pack at low temperatures, protecting the battery pack when charging the battery, and extending the battery pack's service life.

[0061] In this embodiment, a data storage module is connected to the data terminals (PB10 and PB11) of the main control module. The data storage module adopts a data storage chip U6, and the data storage chip U6 is connected to the main control module through the IIC bus.

[0062] In this embodiment, a low-voltage switch S2 is connected to the data terminal (PB2) of the main control module. The low-voltage switch S2 is connected between the data terminal (PB2) of the main control module and ground, which can realize the main output voltage of the battery to be turned on or off with a small switch.

[0063] In this embodiment, the main control module's data terminals (PA13 and PA14) are connected to a simulation debugging interface J3, which is used to perform simulation debugging operations on the present invention.

[0064] In this invention, the power supply module includes a step-down module and a power supply module. The step-down module uses a DC-DC step-down chip U5 to reduce the input positive terminal voltage BN to VDD (+5V in this embodiment) for power supply. The power supply module uses a voltage regulator chip U2 to reduce the +5V power supply to +3.3V for power supply. In this embodiment, the power supply module also includes a reference module. The reference module uses a reference voltage source chip U4 to convert the +5V power supply into a reference voltage VREF, providing a reference voltage for this invention.

[0065] This invention also protects a charging equalization method; please refer to the appendix for details. Figure 23 The method mainly includes the following steps: Step S1: Charge the battery pack using a power supply or charger. At this time, the charging switching module controls the input positive terminal BN to charge the entire battery pack. Meanwhile, the voltage sampling module samples the voltage in real time. Step S2: When the voltage of one or more batteries in the battery pack reaches the set voltage threshold, the main control module controls the main charging control module to shut down the main charging circuit. Step S3: The main control module controls the charging switching module to intelligently switch to the auxiliary charging circuit to charge individual batteries in the battery pack. At this time, the charging switching module controls the input positive terminal BN to supply power to VIN. Step S4: When all battery voltages reach the voltage threshold and cutoff current, turn off the auxiliary charging circuit. Step S5: Turn off the charging circuit. Charging is complete.

[0066] This invention proposes a novel charging equalization circuit that uses a charging switching module to control the switching between overall charging and individual battery charging. This can efficiently equalize the voltage of the battery pack, is simple and easy to implement, and can ensure both charging efficiency and balanced charging of the lithium battery pack, minimizing damage to battery life and improving safety in use.

Claims

1. A lithium battery pack charging equalization circuit, used for charging a battery pack consisting of two or more lithium batteries connected in series, characterized in that: The circuit comprises a lithium battery pack consisting of two or more lithium batteries connected in series, a main control module, a voltage acquisition module, a main charging circuit, an auxiliary charging circuit, and a charging switching module. The voltage acquisition module is connected to the lithium battery pack, and its data output terminal is connected to the main control module. The main charging circuit and the auxiliary charging circuit are respectively connected to the charging switching module, which is connected to the main control module. The main charging circuit is used to charge the entire series-connected lithium battery pack, and the auxiliary charging circuit is used to charge a single lithium battery individually.

2. The lithium battery pack charging equalization circuit according to claim 1, characterized in that: The auxiliary charging circuit consists of two or more auxiliary charging modules. Each auxiliary charging module has the same circuit structure and connection method. Each auxiliary charging module includes a power controller U211, an inductor L1, and a battery charging management chip U212. The power input terminal of the power controller U211 is connected to the auxiliary charging interface of the charging control module. The ground terminal of the power controller U211 is connected to the negative input interface C-. The first and second pins of the inductor L1 are connected between the auxiliary input DC power supply VIN and the SW pin of the power controller U211. The third and fourth pins of the inductor L1 are connected to the battery charging management chip U212. The BAT pin of the battery charging management chip U212 is connected to the positive terminal of the battery B1.

3. The lithium battery pack charging equalization circuit according to claim 1, characterized in that: The charging switching module includes transistor Q1, PMOS transistor QCA, and PMOS transistor QCB. The base of transistor Q1 is connected to the control pin of the main control module, the emitter of transistor Q1 is grounded, the collector of transistor Q1 is connected to the gate of PMOS transistors QCA and QCB through a resistor, the drain of PMOS transistors QCA and QCB is connected, the source of PMOS transistor QCA is connected to the positive input terminal BN, and the source of PMOS transistor QCB is connected to the auxiliary input DC power supply VIN.

4. The lithium battery pack charging equalization circuit according to claim 1, characterized in that: The main charging circuit adopts a main charging control module, which uses an NMOS transistor QC. The gate of the NMOS transistor QC is connected to a control pin of the main control module through a resistor. The source of the NMOS transistor QC is the input negative terminal C- interface. A Zener diode ZD2 is connected in parallel between the gate and the source of the NMOS transistor QC.

5. The lithium battery pack charging equalization circuit according to claim 1, characterized in that: The voltage acquisition module uses one or more voltage acquisition chips, which are connected in a cascaded or independent manner. The signal output terminal of each voltage acquisition chip is directly or indirectly connected to the data terminal of the main control module. Each voltage acquisition chip acquires the voltage of one or more individual lithium batteries.

6. A charging equalization method using the lithium battery pack charging equalization circuit as described in any one of claims 1 to 5, characterized in that: The method includes the following steps: Step S1: Charge the battery pack using a power supply or charger. At the same time, the voltage sampling module samples the voltage in real time. Step S2: When the voltage of one or more batteries in the battery pack reaches the set voltage threshold, the main control module controls the main charging control module to shut down the main charging circuit. Step S3: The main control module controls the charging switching module to intelligently switch to the auxiliary charging circuit to charge individual batteries in the battery pack. Step S4: When all battery voltages reach the voltage threshold and cutoff current, turn off the auxiliary charging circuit. Step S5: Turn off the charging circuit. Charging is complete.

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