Charging non-discharging BMS application circuit and charging and discharging control method
The negative electrode control circuit, built with low-cost discrete components, solves the problems of malfunction and high cost in the charging process of traditional BMS application circuits, achieves 0V charging port voltage and improves safety, and is suitable for lithium battery management systems.
Patent Information
- Application Number
- CN202511216394.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2025-11-21
AI Technical Summary
Traditional BMS application circuits are prone to malfunctions during charging and discharging, and the negative control scheme cannot achieve 0V voltage at the charging port, resulting in safety hazards and high costs.
The negative electrode control circuit is constructed using low-cost discrete components. The control logic is built using transistors, diodes, and resistors to achieve the function of charging without discharging. The charging port voltage is isolated by MOSFETs and Zener diodes to prevent the discharge circuit from conducting during charging.
It achieves 0V voltage at the charging port during charging, avoiding malfunctions and electric shock risks, reducing hardware costs and complexity, and improving safety and production efficiency.
Smart Images
Figure CN120999836A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of charge and discharge control technology, specifically to a charging-non-discharging BMS application circuit and a charge and discharge control method. Background Technology
[0002] In the field of modern battery management systems (BMS) applications, the booming development of various electronic devices and new energy applications has placed extremely high demands on the safety, efficiency, and intelligence of battery charging and discharging management. Traditional BMS application circuits have revealed many shortcomings when dealing with the complex operating conditions during charging and discharging.
[0003] If the device discharges during charging, it may cause malfunctions and pose a danger; in addition, a live charging port can affect the charger's detection.
[0004] The current market solutions control the charging of the positive circuit. However, the cost of the positive control chip is high. Existing charging circuits control the negative circuit, making it impossible to achieve a 0V voltage at the charging port. Summary of the Invention
[0005] The purpose of this application is to provide a charging-non-discharging BMS application circuit and a charging-discharging control method to solve the problems mentioned in the background art.
[0006] To solve the above-mentioned technical problems, this application provides the following technical solution: The first aspect discloses a charging-non-discharging BMS application circuit, including a BMS control chip, which is configured with a CTLD pin, a discharge control pin, and a charging control pin. This includes a discharge MOSFET, whose drain is connected to the negative terminal of the discharge port, and whose source is connected to the negative terminal of the battery; the gate of the discharge MOSFET is connected to the discharge control pin, and is turned on or off by the signal from the discharge control pin. It includes a charging MOSFET, the drain of which is connected to the negative terminal of the battery, and the source of which is connected to the negative terminal of the charging port; the gate of the charging MOSFET is connected to the charging control pin and is turned on or off by the signal from the charging control pin.
[0007] The source of the discharge MOSFET is connected to the negative terminal of the battery, specifically: the source of the discharge MOSFET is connected to the negative terminal of the battery through the fifth resistor.
[0008] It includes a first transistor, the emitter of which is connected to one end of a first diode and one end of a second diode via a first resistor; the other end of the first diode is connected to the CTLD pin, and the other end of the second diode is connected to the discharge control pin.
[0009] The emitter of the first transistor is connected to the collector of the second transistor through the second resistor; the collector of the first transistor is connected to the base of the second transistor; the collector of the first transistor is connected to one end of the fourth resistor; the other end of the fourth resistor is connected to the negative terminal of the charging port.
[0010] The base of the second transistor is connected to the negative terminal of the battery through the third resistor, and the emitter of the second transistor is connected to the negative terminal of the charging port.
[0011] It includes a third diode, one end of which is connected to the negative terminal of the charging port, and the other end of which is connected to the source of the charging MOSFET to isolate the circuit.
[0012] It includes a first Zener diode, one end of which is connected to the CTLD pin and the other end of which is connected to the negative terminal of the battery. It also includes a second Zener diode, one end of which is connected to the discharge control pin and the other end of which is connected to the negative terminal of the battery.
[0013] The second aspect discloses a charging and discharging control method, including the following steps: When no external charger is connected, the negative terminal of the charging port is floating, and the voltage between the negative terminal of the charging port and the positive terminal of the discharge port is 0V. With the negative terminal of the charging port floating, the first and second transistors are not conducting, the CTLD signal is high, the discharge control pin is not pulled low, and the discharge MOSFET is conducting normally. The negative terminal of the battery and the negative terminal of the discharge port are connected together through the fifth resistor and the discharge MOSFET, allowing for external discharge. When a charger is connected, the voltage of the negative terminal of the battery is higher than the voltage of the negative terminal of the charging port. The second transistor conducts, the base of the first transistor is pulled low, and the CTLD or discharge control pin DSG is connected to the negative terminal of the charging port through the diode, the first resistor, the first transistor, and the second transistor. The signal is pulled to ground, and the discharge MOSFET is turned off, thus achieving the function of charging without discharging.
[0014] Furthermore, the steps include: when the charger is not removed after the battery is fully charged, there is no voltage difference between the negative terminal of the battery and the negative terminal of the charging port. The first resistor, the first transistor, the fourth resistor, and the negative terminal of the charging port form a circuit. The voltage applied to the fourth resistor turns on the second transistor, locking the signal of the CTLD / discharge control pin. The discharge MOSFET remains in the off state.
[0015] Furthermore, the steps include: when the charger is removed, the negative terminal of the charging port is left floating, the second transistor and the first transistor are turned off, the CTLD / discharge control pin signal is pulled high, and the discharge MOSFET enters the conduction state.
[0016] Compared with existing technologies, this application has the following advantages: the battery's charging port voltage is controlled to be 0V at the negative terminal, thus meeting the requirement of charging without discharging. In traditional solutions, if the discharge circuit is not shut off during charging, it may cause electrical appliances to malfunction (such as the device unexpectedly starting up while charging), leading to current fluctuations, component overload, or even fire hazards. This application achieves "charging without discharging" through precise charging and discharging control logic, fundamentally avoiding the conflict risk of simultaneous charging and discharging. When no charger is connected, the charging port (C-) maintains a voltage of 0V due to the isolation of the open circuit by diode D3; it also maintains 0V during charging, avoiding the risk of electric shock caused by users or devices coming into contact with the live interface, thus greatly improving safety.
[0017] In existing technologies, the "positive electrode control charging circuit" requires a high-cost dedicated control chip, while the traditional "negative electrode control scheme" cannot achieve a 0V voltage. This application, through an innovative negative electrode control circuit, uses low-cost discrete components (transistors Q1 and Q2, diodes D1-D3, resistors R1-R5, Zener diodes ZD1-ZD2, etc.) to construct the control logic, eliminating the need for a high-priced positive electrode control chip and significantly reducing hardware costs. The circuit structure is simple, reducing the number of components and wiring complexity, lowering production, debugging, and maintenance costs, and making it suitable for large-scale industrial production. Attached Figure Description
[0018] Figure 1 The schematic diagram of the charging-non-discharging BMS application circuit of this application is shown. Detailed Implementation
[0019] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0020] like Figure 1 The charging-non-discharging BMS application circuit of this application includes a BMS control chip, which is configured with a CTLD pin (discharge MOS control pin of lithium battery control chip), a discharge control pin DSG, and a charging control pin CHG. This includes a discharge MOSFET Q3, whose drain is connected to the negative terminal P- of the discharge port, and whose source is connected to the negative terminal B- of the battery through the fifth resistor R5; the gate of the discharge MOSFET Q3 is connected to the discharge control pin DSG, and is turned on or off by the signal of the discharge control pin DSG; when the discharge MOSFET Q3 is turned on, the negative terminal B- of the battery and the negative terminal P- of the discharge port are connected through the drain and source terminals of the discharge MOSFET Q3 and R5, forming a discharge circuit.
[0021] like Figure 1 The charging-non-discharging BMS application circuit of this application includes a charging MOSFET Q4, the drain of the charging MOSFET Q4 is connected to the negative terminal B- of the battery, and the source of the charging MOSFET Q4 is connected to the negative terminal C- of the charging port; the gate of the charging MOSFET Q4 is connected to the charging control pin CHG and is turned on or off by the signal of the charging control pin CHG.
[0022] like Figure 1 In the charging-without-discharging BMS application circuit of this application, the emitter of the first transistor Q1 is connected to one end of the first diode D1 and one end of the second diode D2 through the first resistor R1; the other end of the first diode D1 is connected to the CTLD pin, and the other end of the second diode D2 is connected to the discharge control pin DSG.
[0023] like Figure 1 The emitter of the first transistor Q1 is connected to the collector of the second transistor Q2 through the second resistor R2; the collector of the first transistor Q1 is connected to the base of the second transistor Q2; the collector of the first transistor Q1 is connected to one end of the fourth resistor R4; the other end of the fourth resistor R4 is connected to the negative terminal C- of the charging port.
[0024] like Figure 1 The base of the second transistor Q2 is connected to the negative terminal B- of the battery through the third resistor R3, and the emitter of the second transistor Q2 is directly connected to the negative terminal C- of the charging port.
[0025] like Figure 1 One end of the third diode D3 is connected to the negative terminal C- of the charging port, and the other end of the third diode D3 is connected to the source of the charging MOSFET Q4 to isolate the circuit. One end of the first Zener diode ZD1 is connected to the CTLD pin, and the other end is connected to the negative terminal B- of the battery.
[0026] The implementation principle of this application is as follows: When no external charger is connected, the negative terminal C- of the charging port is floating. Due to the isolation of the discharge circuit by the third diode D3, the voltage across the negative terminal C- of the charging port and the positive terminal P+ of the discharge port is 0V. With the negative terminal C- of the charging port floating, the first transistor Q1 and the second transistor Q2 are not conducting, the CTLD signal is at a high level, the discharge control pin DSG is not pulled low, and the discharge MOSFET Q3 is normally conducting. The negative terminal B- of the battery and the negative terminal P- of the discharge port are connected together through the fifth resistor R5 and the discharge MOSFET Q3, allowing for external discharge.
[0027] When the charger is connected, the voltage at the negative terminal B- of the battery is higher than the voltage at the negative terminal C- of the charging port. The second transistor Q2 is turned on, and the base of the first transistor Q1 is pulled low. The CTLD or discharge control pin DSG is connected to the negative terminal C- of the charging port through a diode, the first resistor R1, the first transistor Q1, and the second transistor Q2. The signal is pulled to ground, and the discharge MOSFET Q3 is turned off, thus achieving the function of charging without discharging.
[0028] When the charger is not removed after the battery is fully charged, there is no voltage difference between the battery's negative terminal B- and the charging port's negative terminal C-. The first resistor R1, the first transistor Q1, the fourth resistor R4, and the charging port's negative terminal C- form a circuit. The voltage applied to the fourth resistor R4 turns on the second transistor Q2, locking the signal on the CTLD / discharge control pin DSG. The discharge MOSFET Q3 remains in the off state.
[0029] After the charger is removed, the negative terminal C- of the charging port is left floating, the second transistor Q2 and the first transistor Q1 are turned off, the DSG signal on the CTLD / discharge control pin is pulled high, and the discharge MOSFET Q3 enters the conducting state. The first Zener diode ZD1 and the second Zener diode ZD2 are used to prevent the BMS control chip from being damaged by excessive voltage difference between the charger and the negative terminal B- of the battery, thus playing a protective role.
[0030] Therefore, this application also discloses a charging and discharging control method, including the following steps: When no external charger is connected, the negative terminal C- of the charging port is floating, and the voltage across the negative terminal C- of the charging port and the positive terminal P+ of the discharge port is 0V. With the negative terminal C- of the charging port floating, the first transistor Q1 and the second transistor Q2 are not conducting, the CTLD signal is high, the discharge control pin DSG is not pulled low, and the discharge MOSFET Q3 is conducting normally. The negative terminal B- of the battery and the negative terminal P- of the discharge port are connected together through the fifth resistor R5 and the discharge MOSFET Q3, allowing for external discharge. When the charger is connected, the voltage at the negative terminal B- of the battery is higher than the voltage at the negative terminal C- of the charging port. The second transistor Q2 is turned on, and the base of the first transistor Q1 is pulled low. The CTLD or discharge control pin DSG is connected to the negative terminal C- of the charging port through a diode, the first resistor R1, the first transistor Q1, and the second transistor Q2. The signal is pulled to ground, and the discharge MOSFET Q3 is turned off, thus achieving the function of charging without discharging.
[0031] Further steps include: when the charger is not removed after the battery is fully charged, there is no voltage difference between the negative terminal B- of the battery and the negative terminal C- of the charging port. The first resistor R1, the first transistor Q1, the fourth resistor R4, and the negative terminal C- of the charging port form a circuit. The voltage applied to the fourth resistor R4 turns on the second transistor Q2, locking the signal of the CTLD / discharge control pin DSG. The discharge MOSFET Q3 remains in the off state.
[0032] Further steps include: when the charger is removed, the negative terminal C- of the charging port is left floating, the second transistor Q2 and the first transistor Q1 are turned off, the DSG signal on the CTLD / discharge control pin is pulled high, and the discharge MOSFET Q3 enters the conducting state.
[0033] The lithium battery control chip models used in the charging-non-discharging circuit application scenarios of this application include: NXP Semiconductors' MC33771B / MC33771C series: These two chips are lithium-ion battery cell controller ICs for automotive and industrial applications, suitable for lithium-ion batteries, HEVs (Hybrid Electric Vehicles), EVs (Electric Vehicles), ESS (Energy Storage Systems), and UPS (Uninterruptible Power Supply) systems. They feature ADC conversion of differential battery voltage and current, coulomb counting, and temperature measurement, and also integrate balancing transistors and diagnostic functions. They support standard SPI and transformer-isolated daisy-chain communication (in conjunction with the MC33664) for data exchange with MCUs, meeting complex battery management needs. Although not explicitly mentioned in the documentation, in similar automotive and industrial battery management scenarios, it is speculated that pin functions such as CTLD, DSG, and CHG can be controlled through programming configuration to achieve functions such as charging without discharging.
[0034] MC33772B / MC33772C: Suitable for automotive electronics and industrial control applications such as 14V lithium batteries, HEVs, EVs, ESS, and UPS systems. They possess similar functionalities to the MC33771 series, such as voltage, current, and temperature measurement, as well as embedded balancing and diagnostic functions. Their overall functional architecture aligns well with application scenarios, and they also offer the potential to implement CTLD, DSG, and CHG pin function control, thus adapting to charging-without-discharging circuit designs.
[0035] Renesas Electronics Corporation's RAJ240090 / RAJ240100 series are lithium-ion battery fuel gauge integrated circuits that integrate MCU and AFE devices, powered by the Renesas RL78 CPU core, and feature multiple low-power modes. They support 3-8 cells (RAJ240090) or 3-10 cells (RAJ240100) of lithium-ion or lithium-polymer batteries connected in series, measuring battery voltage, current, and temperature, and performing remaining capacity estimation, overcurrent / voltage / temperature protection, and other operations. Their multi-functional processing capabilities and high level of integration in battery management allow for programmable control of the CTLD, DSG, and CHG pins to meet the requirements of charge-to-discharge circuits in terms of power monitoring and charge / discharge control, making them suitable for battery management in consumer electronics, portable devices, and other fields.
Claims
1. A charging-without-discharging BMS application circuit, characterized in that, Includes a BMS control chip, which is configured with CTLD pin, discharge control pin, and charge control pin; This includes a discharge MOSFET, whose drain is connected to the negative terminal of the discharge port, and whose source is connected to the negative terminal of the battery; the gate of the discharge MOSFET is connected to the discharge control pin, and is turned on or off by the signal from the discharge control pin. It includes a charging MOSFET, the drain of which is connected to the negative terminal of the battery, and the source of which is connected to the negative terminal of the charging port; the gate of the charging MOSFET is connected to the charging control pin and is turned on or off by the signal from the charging control pin.
2. The BMS application circuit for charging without discharging according to claim 1, characterized in that, The source of the discharge MOSFET is connected to the negative terminal of the battery, specifically: the source of the discharge MOSFET is connected to the negative terminal of the battery through the fifth resistor.
3. The BMS application circuit for charging without discharging according to claim 2, characterized in that, It includes a first transistor, the emitter of which is connected to one end of a first diode and one end of a second diode via a first resistor; the other end of the first diode is connected to the CTLD pin, and the other end of the second diode is connected to the discharge control pin.
4. The BMS application circuit for charging without discharging according to claim 3, characterized in that, The emitter of the first transistor is connected to the collector of the second transistor through the second resistor; the collector of the first transistor is connected to the base of the second transistor; the collector of the first transistor is connected to one end of the fourth resistor; the other end of the fourth resistor is connected to the negative terminal of the charging port.
5. The BMS application circuit for charging without discharging according to claim 4, characterized in that, The base of the second transistor is connected to the negative terminal of the battery through the third resistor, and the emitter of the second transistor is connected to the negative terminal of the charging port.
6. The BMS application circuit for charging without discharging according to claim 5, characterized in that, It includes a third diode, one end of which is connected to the negative terminal of the charging port, and the other end of which is connected to the source of the charging MOSFET to isolate the circuit.
7. The BMS application circuit for charging without discharging according to claim 6, characterized in that, It includes a first Zener diode, one end of which is connected to the CTLD pin and the other end of which is connected to the negative terminal of the battery. It also includes a second Zener diode, one end of which is connected to the discharge control pin and the other end of which is connected to the negative terminal of the battery.
8. A charging and discharging control method, characterized in that, Including the following steps: When no external charger is connected, the negative terminal of the charging port is floating, and the voltage between the negative terminal of the charging port and the positive terminal of the discharge port is 0V. With the negative terminal of the charging port floating, the first and second transistors are not conducting, the CTLD signal is high, the discharge control pin is not pulled low, and the discharge MOSFET is conducting normally. The negative terminal of the battery and the negative terminal of the discharge port are connected together through the fifth resistor and the discharge MOSFET, allowing for external discharge. When a charger is connected, the voltage of the negative terminal of the battery is higher than the voltage of the negative terminal of the charging port. The second transistor conducts, the base of the first transistor is pulled low, and the CTLD or discharge control pin DSG is connected to the negative terminal of the charging port through the diode, the first resistor, the first transistor, and the second transistor. The signal is pulled to ground, and the discharge MOSFET is turned off, thus achieving the function of charging without discharging.
9. The charging and discharging control method according to claim 8, characterized in that, The steps include: when the charger is not removed after the battery is fully charged, there is no voltage difference between the negative terminal of the battery and the negative terminal of the charging port. The first resistor, the first transistor, the fourth resistor, and the negative terminal of the charging port form a circuit. The voltage is applied to the fourth resistor to turn on the second transistor, locking the signal on the CTLD / discharge control pin. The discharge MOSFET is still in the off state.
10. The charging and discharging control method according to claim 8, characterized in that, The steps include: When the charger is removed, the negative terminal of the charging port is left floating, the second transistor and the first transistor are turned off, the CTLD / discharge control pin signal is pulled high, and the discharge MOSFET enters the conduction state.