A constant current source based charging on and off bi-directional acceleration circuit
By using a bidirectional acceleration circuit for charging on and off based on a constant current source, and by utilizing the synergistic operation of components such as transistors and resistors, the problem of slow switching speed of the charging MOSFET is solved, thereby improving the lifespan of the charging MOSFET and the reliability of the battery management system.
Patent Information
- Application Number
- CN202522538748.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-11-03
- Estimated Expiration
- 2035-11-28
AI Technical Summary
In the charging and discharging drive of the battery management chip in BMS, the turn-on and turn-off times of the charging MOS are relatively long, which makes it prone to thermal damage or electrical breakdown under high current charging and discharging scenarios.
Design a bidirectional acceleration circuit for charging on and off based on a constant current source. By reasonably arranging components such as transistors Q38, Q15, Q43, diode D21, resistors R48, and R166, the constant current source driving characteristics work in conjunction with the components to achieve rapid on and off of the charging MOSFET.
It shortens the turn-on and turn-off time of the charging MOSFET, improves its service life and the operational reliability of the battery management system, and avoids thermal damage and electrical breakdown.
Smart Images
Figure CN224935425U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of battery charging, and in particular to a bidirectional acceleration circuit for charging on and off based on a constant current source. Background Technology
[0002] In the charging and discharging drive of the battery management chip in BMS, after discharge protection, the MOS and drive circuit of the charging section will be set high to the battery B+ potential through the equivalent resistance of the battery positive terminal and the load. In order to prevent high voltage from backflowing into the battery management chip and to reduce power consumption, the drive pin of the charging MOS is generally designed as an open-drain design or a constant current source design. However, this design will result in a relatively long rise and fall time for the MOS to turn on and off. In high current charging and discharging scenarios, the MOS is prone to thermal damage or electrical breakdown due to the slow switching and the stress of current and voltage. This needs to be solved urgently. Utility Model Content
[0003] To address the shortcomings of the prior art, this application provides a bidirectional acceleration circuit for charging on and off based on a constant current source.
[0004] The above-mentioned inventive objective of this application is achieved through the following technical solutions: A bidirectional acceleration circuit for charging on and off based on a constant current source includes a transistor Q15, the base of transistor Q15 is connected to a transistor Q38 and a resistor R166, the base of transistor Q15 is connected to the emitter of transistor Q38, the collector of transistor Q38 is connected to a diode D21, the diode D21 is connected to the battery B+, the base of transistor Q38 is connected to resistors R38 and R48, the other end of resistor R38 is connected to a diode D20, the diode D20 is connected to a microcontroller U4, and the second pin of resistor R166 is connected to a transistor Q43. The emitter of transistor Q15 is connected to a charging MOS element group for controlling the charging switch, and the collector of transistor Q43 and the other end of resistor R48 are both connected to the charging MOS element group.
[0005] Preferably, the collector of transistor Q15 is connected to resistor R50 and capacitor C20, the other end of resistor R50 is connected to diode D21, and capacitor C20 is connected to the charging MOS element group.
[0006] Preferably, the charging MOS element group includes a MOS transistor QC4, the gate of the MOS transistor QC4 is connected to a resistor R183 and a diode D17, the source of the MOS transistor QC4 is connected to the collector of a transistor Q43, and the drain of the MOS transistor QC4 is connected to a MOS transistor QC2 and connected to a microcontroller U4.
[0007] Preferably, the emitter of transistor Q15 is connected to the emitter of transistor Q43.
[0008] Preferably, the base of transistor Q43 is connected to the second pin of resistor R166.
[0009] Compared with the prior art, the beneficial effects of this utility model are: This invention utilizes a bidirectional acceleration circuit constructed by rationally arranging transistors Q38, Q15, Q43, diode D21, and resistors R48 and R166. It cleverly leverages the constant current source's driving characteristics and the coordinated operation of these components to achieve bidirectional acceleration for the charging MOSFET's on / off states. Specifically, when the charger is connected, the constant current output from microcontroller U4 causes a voltage drop across resistor R48 via a related circuit, triggering transistors Q38 and Q15 to conduct sequentially. The battery's B+ component forms a low-resistance path through diode D21 and the conducted Q38 and Q15, rapidly providing the driving voltage to the charging MOSFET assembly and shortening the on / off time. When the battery overvoltage protection is activated, the microcontroller U4 stops constant current output, the voltage drop across R48 disappears, Q38 and Q15 are cut off, and the base of transistor Q43 is pulled down through resistor R48, quickly releasing the residual voltage of the input capacitor of the charging MOS element group and shortening the turn-off falling edge. This acceleration circuit design, based on the advantages of existing constant current source designs such as high voltage reverse current protection and low power consumption, can solve the technical pain points of slow switching speed of charging MOS transistors and easy thermal damage or electrical breakdown due to current or voltage stress in high current scenarios, significantly improving the service life of charging MOS transistors and the operational reliability of the battery management system. Attached Figure Description
[0010] Figure 1 This is a schematic diagram of the overall circuit of this application; Figure 2 This is a schematic diagram of an implementation circuit in one embodiment of this application. Detailed Implementation
[0011] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of this application, including various details to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.
[0012] It should be noted that the terms "first," "second," etc., used in this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with this disclosure.
[0013] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.
[0014] The following is a reference appendix. Figure 1 To be continued Figure 2 This application describes a bidirectional acceleration circuit for charging on and off based on a constant current source.
[0015] like Figure 1 and Figure 2 As shown, the bidirectional acceleration circuit for charging on and off based on a constant current source includes transistor Q15. The base of transistor Q15 is connected to transistor Q38 and resistor R166. The base of transistor Q15 is connected to the emitter of transistor Q38. The collector of transistor Q38 is connected to diode D21, which is connected to the battery B+. The base of transistor Q38 is connected to resistors R38 and R48. The other end of resistor R38 is connected to diode D20, which is connected to microcontroller U4. The second pin of resistor R166 is connected to transistor Q43. The emitter of transistor Q15 is connected to a charging MOS element group for controlling the charging switch. The collector of transistor Q43 and the other end of resistor R48 are both connected to the charging MOS element group. As an example, the microcontroller U4 can be an AMG8824A.
[0016] Furthermore, the collector of transistor Q15 is connected to resistor R50 and capacitor C20. The other end of resistor R50 is connected to diode D21, and capacitor C20 is connected to the charging MOS element group.
[0017] Furthermore, the emitter of transistor Q15 is connected to the emitter of transistor Q43.
[0018] Furthermore, the base of transistor Q43 is connected to the second pin of resistor R166.
[0019] Preferably, the charging MOS element group includes MOS transistor QC4, the gate of MOS transistor QC4 is connected to resistor R183 and diode D17, the source of MOS transistor QC4 is connected to the collector of transistor Q43, and the drain of MOS transistor QC4 is connected to MOS transistor QC2 and connected to microcontroller U4.
[0020] Circuit principle: When the charger is not connected, the CHG pin of the microcontroller U4 is powered by a constant current source, but because MOSFETs QC1 and QC3 are in the off state (see the location of MOSFETs QC1 and QC3 for details), Figure 2 Therefore, the CHG pin cannot form a constant current source circuit through resistors R38 and R48. Resistor R48 does not produce a voltage drop, so transistors Q38 and Q15 are both in the off state, transistor Q43 is also in the off state, and MOSFETs QC2 and QC4 have no driving voltage and are both in the off state. After the charger is connected, the CHG pin of the microcontroller U4 continuously powers on the constant current source. The C- pin forms a constant current source circuit through the charger. At this time, resistor R48 generates a voltage drop of about 12V, which turns on transistor Q38. The conduction of transistor Q38 further drives transistor Q15 to conduct, which in turn powers MOSFETs QC2 and QC4, enabling the charging MOSFETs to conduct and charge. Meanwhile, transistor Q43 is in the off state. The battery B+ voltage conducts through diode D21, transistor Q38, and transistor Q15 to power MOSFETs QC2 and QC4. Because the internal resistance of transistors Q38 and Q15 is low after conduction, MOSFETs QC2 and QC4 are powered on quickly, accelerating their rising edge. When the overvoltage protection is activated, the internal power supply of the CHG constant current source of the microcontroller U4 is disconnected. At this time, the voltage drop across resistor R48 disappears, transistor Q38 is cut off, transistor Q15 is cut off, and the drive voltage of MOSFETs QC2 and QC4 is disconnected. At the same time, the base of transistor Q43 is pulled down through resistor R48, causing transistor Q43 to conduct quickly, which rapidly discharges the residual voltage of the input capacitors of MOSFETs QC2 and QC4. This accelerates the turn-off of MOSFETs QC2 and QC4, and the falling edge decreases rapidly. Among them, resistor R50 is a current-limiting resistor, and resistor R166 is the bias resistor of the base of Q43.
[0021] This invention utilizes a bidirectional acceleration circuit constructed by rationally arranging transistors Q38, Q15, Q43, diode D21, and resistors R48 and R166. It cleverly leverages the constant current source's driving characteristics and the coordinated operation of these components to achieve bidirectional acceleration for the charging MOSFET's on / off states. Specifically, when the charger is connected, the constant current output from microcontroller U4 causes a voltage drop across resistor R48 via a related circuit, triggering transistors Q38 and Q15 to conduct sequentially. The battery's B+ component forms a low-resistance path through diode D21 and the conducted Q38 and Q15, rapidly providing the driving voltage to the charging MOSFET assembly and shortening the on / off time. When the battery overvoltage protection is activated, the microcontroller U4 stops constant current output, the voltage drop across R48 disappears, Q38 and Q15 are cut off, and the base of transistor Q43 is pulled down through resistor R48, quickly releasing the residual voltage of the input capacitor of the charging MOS element group and shortening the turn-off falling edge. This acceleration circuit design, based on the advantages of existing constant current source designs such as high voltage reverse current protection and low power consumption, can solve the technical pain points of slow switching speed of charging MOS transistors and easy thermal damage or electrical breakdown due to current or voltage stress in high current scenarios, significantly improving the service life of charging MOS transistors and the operational reliability of the battery management system.
[0022] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A bidirectional acceleration circuit for charging on and off based on a constant current source, characterized in that, The system includes transistor Q15, whose base is connected to transistor Q38 and resistor R166. The base of transistor Q15 is connected to the emitter of transistor Q38. The collector of transistor Q38 is connected to diode D21, which is connected to battery B+. The base of transistor Q38 is connected to resistors R38 and R48. The other end of resistor R38 is connected to diode D20, which is connected to microcontroller U4. The second pin of resistor R166 is connected to transistor Q43. The emitter of transistor Q15 is connected to a charging MOS element group for controlling the charging switch, and the collector of transistor Q43 and the other end of resistor R48 are both connected to the charging MOS element group.
2. The bidirectional acceleration circuit for charging on and off based on a constant current source as described in claim 1, characterized in that, The collector of transistor Q15 is connected to resistor R50 and capacitor C20. The other end of resistor R50 is connected to diode D21, and capacitor C20 is connected to the charging MOS element group.
3. The bidirectional acceleration circuit for charging on and off based on a constant current source as described in claim 1, characterized in that, The charging MOS component group includes MOS transistor QC4. The gate of MOS transistor QC4 is connected to resistor R183 and diode D17. The source of MOS transistor QC4 is connected to the collector of transistor Q43. The drain of MOS transistor QC4 is connected to MOS transistor QC2 and is connected to microcontroller U4.
4. The bidirectional acceleration circuit for charging on and off based on a constant current source as described in claim 1, characterized in that, The emitter of transistor Q15 is connected to the emitter of transistor Q43.
5. The bidirectional acceleration circuit for charging on and off based on a constant current source as described in claim 1, characterized in that, The base of transistor Q43 is connected to the second pin of resistor R166.