Lithium battery battery replacement cabinet

Abstract

The application relates to the technical field of battery replacement cabinets, and provides a lithium battery replacement cabinet, which comprises a main power module, a backup battery and a charging switch control circuit, the main power module is used for connecting to commercial power and outputting a direct-current power supply voltage; the main power module supplies power to a lithium battery to be charged through a first switching device, and the backup battery supplies power to the lithium battery to be charged through a second switching device; the charging switch control circuit is electrically connected with the main power module, the first switching device and the second switching device; when the main power module is powered on, the charging switch control circuit controls the first switching device to be turned on and the second switching device to be turned off; when the main power module is powered off, the charging switch control circuit controls the first switching device to be turned off and the second switching device to be turned on. Based on the above, the power supply is switched by directly inverting the hardware level, the switching response speed is fast, and the operation reliability of the lithium battery replacement cabinet under the working conditions of commercial power fluctuation and instantaneous power failure is improved.

Description

Technical Field

[0001] This invention relates to the field of battery swapping cabinet technology, and in particular to a lithium battery swapping cabinet. Background Technology

[0002] Lithium battery swapping cabinets, as core equipment for centralized storage, charging, and self-service battery swapping of new energy batteries, are widely used in electric vehicle mobility scenarios. The cabinets feature multiple independent battery compartments, enabling lithium battery storage, constant-voltage charging, and automatic swapping. To ensure uninterrupted critical functions under abnormal mains power conditions, existing lithium battery swapping cabinets are generally equipped with a dual-power supply architecture. The main power module adapts to mains power supply, while a backup battery provides emergency power redundancy. This ensures continuous operation of core modules such as the main control unit, communication system, and door control, preventing equipment failure, data loss, and door jamming caused by power outages.

[0003] Most existing dual-power switching solutions employ a software switching mode using an MCU (Microcontroller Unit) in conjunction with an analog-to-digital sampling circuit. This solution uses the MCU's ADC (Analog-to-Digital Converter) to acquire the main power supply voltage signal in real time, relies on program algorithms and interrupt instructions to determine the power supply status, and then outputs control signals to complete the switching between the main power supply and the backup battery. However, this software switching architecture has inherent technical defects: on the one hand, voltage sampling, algorithm calculation, and instruction execution have millisecond-level response delays, which can easily lead to power supply switching interruptions under conditions such as instantaneous drops in mains power, voltage fluctuations, and instantaneous power outages, causing stability issues such as instantaneous device restarts, loss of operating data, and battery compartment door locking; on the other hand, intelligent switching solutions relying on MCUs are complex in structure, expensive, and susceptible to factors such as program lag, electromagnetic interference, and program error reports, resulting in low fault tolerance and poor hardware reliability and environmental adaptability. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium battery swapping cabinet, which aims to solve the technical problem of poor reliability in existing dual power supply switching schemes.

[0005] This application provides a lithium battery swapping cabinet, including a main power module, a backup battery and a charging switching control circuit. The main power module is used to connect to the mains power and output a DC power supply voltage. The main power module supplies power to the lithium battery to be charged through a first switching device, and the backup battery supplies power to the lithium battery to be charged through a second switching device. The charging switching control circuit is electrically connected to the main power module, the first switching device, and the second switching device, respectively. When the charging switching control circuit detects that the main power module is powered on, it controls the first switching device to be turned on and the second switching device to be turned off. When the charging switching control circuit detects that the main power module is powered off, it controls the first switching device to be turned off and the second switching device to be turned on.

[0006] In one embodiment, the charging switching control circuit includes a first NPN transistor and a second NPN transistor. The base of the first NPN transistor is electrically connected to the output terminal of the main power module, the emitter of the first NPN transistor is grounded, and the collector of the first NPN transistor is electrically connected to the first switching device to control the switching on and off of the first switching device.

[0007] In one embodiment, the base of the second NPN transistor is electrically connected to the output terminal of the main power module, the emitter of the second NPN transistor is grounded, and the collector of the second NPN transistor is electrically connected to the second switching device to control the switching on and off of the second switching device.

[0008] In one embodiment, the output terminal of the main power module is grounded via a first resistor and a second resistor connected in series, and the base of the first NPN transistor is electrically connected to the voltage divider node of the first resistor and the second resistor.

[0009] In one embodiment, the collector of the first NPN transistor is electrically connected to the first switching device through a third resistor.

[0010] In one embodiment, the base of the second NPN transistor is grounded through a first capacitor.

[0011] In one embodiment, the collector of the second NPN transistor is electrically connected to the second switching device through a fourth resistor.

[0012] In one embodiment, the charging switching control circuit further includes a third NPN transistor, the base of which is electrically connected to the output terminal of the main power module, the collector of which is electrically connected to the base of the second NPN transistor, and the emitter of which is grounded.

[0013] In one embodiment, the output of the main power module is grounded via a fifth and a sixth resistor connected in series, and the base of the third NPN transistor is electrically connected to the voltage divider node of the fifth and sixth resistors.

[0014] In one embodiment, the first switching device includes a first PMOS transistor, the source of which is electrically connected to the output terminal of the main power module, the drain of which is electrically connected to the lithium battery to be charged, and the gate of which is electrically connected to the charging switching control circuit.

[0015] In one embodiment, the second switching device includes a second PMOS transistor, the source of which is electrically connected to the positive terminal of the backup battery, the drain of which is electrically connected to the lithium battery to be charged, and the gate of which is electrically connected to the charging switching control circuit.

[0016] In one embodiment, the lithium battery swapping cabinet includes a first diode, the anode of the first diode being connected to the source of the second PMOS transistor, and the cathode of the first diode being electrically connected to the gate of the first PMOS transistor through a seventh resistor.

[0017] In one embodiment, the gate of the first PMOS transistor is electrically connected to the output of the main power module through an eighth resistor.

[0018] In one embodiment, the gate of the second PMOS transistor is electrically connected to the positive terminal of the backup battery through a ninth resistor.

[0019] In one embodiment, the lithium battery swapping cabinet further includes a resistor-capacitor absorption branch, which includes a second diode and a tenth resistor. The high-voltage input terminal of the second diode is connected to the positive terminal of the backup battery, the low-voltage discharge terminal of the second diode is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the negative terminal of the backup battery.

[0020] In one embodiment, the lithium battery swapping cabinet further includes a capacitor filter branch, which is connected in parallel with the resistor-capacitor absorption branch, and the capacitor filter branch includes at least two filter capacitors connected in series.

[0021] The beneficial effects of the lithium battery swapping cabinet provided by this invention are as follows: When the main power module is powered on, the charging switching control circuit directly controls the first switching device to be turned on and the second switching device to be turned off, so that the main power module supplies power to the lithium battery to be charged; when the main power module loses power due to an abnormality in the mains power, the charging switching control circuit directly triggers the logic flip by the change in hardware level, turns off the first switching device and turns on the second switching device, and quickly switches to the backup battery for power supply; the lithium battery swapping cabinet provided by this application uses discrete components to build pure hardware switching logic, eliminating the need for a microcontroller and its peripheral sampling circuit, simplifying the hardware architecture and reducing material costs; the power switching is completed by directly flipping the hardware level, the switching response speed is fast, and the operational reliability of the lithium battery swapping cabinet under the conditions of mains power fluctuation and instantaneous power failure is improved. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the principle of the lithium battery swapping cabinet provided in an embodiment of the present invention; Figure 2 This is a circuit diagram of a lithium battery swapping cabinet provided in an embodiment of the present invention.

[0024] The following are the labeling elements in the figure: 10. Lithium battery to be charged; 100. Main power module; 200. Backup battery; 300. Charging switching control circuit; Q1. First NPN transistor; Q2. Second NPN transistor; R1. First resistor; R2. Second resistor; R3. Third resistor; C1. First capacitor; R4. Fourth resistor; Q3. Third NPN transistor; R5. Fifth resistor; R6. Sixth resistor; 410. First switching device; Q4. First PMOS transistor; 420. Second switching device; Q5. Second PMOS transistor; D1. First diode; R7. Seventh resistor; R8. Eighth resistor; R9. Ninth resistor; R11. Eleventh resistor; R12. Twelfth resistor; 610. RC absorption branch; D2. Second diode; R10. Tenth resistor; 620. Capacitor filtering branch; C2. Filter capacitor. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] Throughout this specification, references to "an embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment" or "in some embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, particular features, structures, or characteristics may be combined in any suitable manner.

[0027] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0028] Please refer to Figure 1 and Figure 2 The lithium battery swapping cabinet provided in this application includes a main power module 100, a backup battery 200, and a charging switching control circuit 300. The main power module 100 is used to connect to mains power and output a DC power supply voltage Vin; the main power module 100 supplies power to the lithium battery 10 to be charged (i.e., ...) through a first switching device 410. Figure 2 The backup battery 200 supplies power to the lithium battery 10 to be charged via the second switching device 420 (i.e., the charging voltage Vout in the backup battery 200). Figure 2 The charging voltage Vout in the middle.

[0029] The charging switching control circuit 300 is electrically connected to the main power module 100, the first switching device 410, and the second switching device 420. When the charging switching control circuit 300 detects that the main power module 100 is powered on, it controls the first switching device 410 to turn on and the second switching device 420 to turn off; when the charging switching control circuit 300 detects that the main power module 100 is powered off, it controls the first switching device 410 to turn off and the second switching device 420 to turn on.

[0030] Based on this, when the main power module 100 is powered on, the charging switching control circuit 300 directly controls the first switching device 410 to turn on and the second switching device 420 to turn off, so that the main power module 100 supplies power to the lithium battery 10 to be charged; when the main power module 100 loses power due to an abnormal mains power supply, the charging switching control circuit 300 directly triggers a logic flip based on the change in hardware level, turning off the first switching device 410 and turning on the second switching device 420, quickly switching to the backup battery 200 for power supply; the lithium battery swapping cabinet provided in this application uses discrete components to build pure hardware switching logic, eliminating the need for a microcontroller and its peripheral sampling circuits, simplifying the hardware architecture and reducing material costs; relying on direct hardware level flipping to complete power switching, the switching response speed is fast, improving the operational reliability of the lithium battery swapping cabinet under mains power fluctuations and instantaneous power outages. The pure hardware control link does not have the risk of software failures such as program crashes, deadlocks, or firmware corruption, and can still maintain a definite logic state even in environments with severe electromagnetic interference or extreme temperatures, significantly improving the operational reliability and safety of the swapping cabinet.

[0031] Specifically, the main power module 100 includes an AC-DC converter and its peripheral voltage regulator and filter circuit, which converts AC mains power into DC voltage suitable for charging the lithium battery. The backup battery 200 is an independently configured lithium iron phosphate or ternary lithium battery pack, which only needs to meet the requirements of rapid discharge and energy buffering. Specifically, the main power module 100 is electrically connected to the backup battery 200. When the backup battery 200's charge is lower than a preset charge and the backup battery 200 is not working (i.e., the second switching device 420 is off), the main power module 100 charges the backup battery 200.

[0032] Specifically, the input of the charging switching control circuit 300 is directly coupled to the DC output of the main power module 100 to acquire the bus voltage signal Vin in real time. The output of the charging switching control circuit 300 is connected to the control electrode (such as the gate of a MOSFET, the base of a bipolar transistor, or the coil drive terminal of an electromagnetic relay) of the first switching device 410 and the second switching device 420, respectively. The hardware of the charging switching control circuit 300 directly responds to the physical changes in the output voltage of the main power module 100. For example, when the output voltage of the main power module 100 rises from zero to above a preset threshold, the internal node potential of the circuit flips, causing the first switching device 410 to receive a conduction drive signal, while forcing the second switching device 420 to be in the off state; conversely, when the output voltage of the main power module 100 falls below the preset threshold, the potential flips again, causing the first switching device 410 to be in the off state, and the second switching device 420 to receive a conduction drive signal. This hardware direct-drive mechanism eliminates the millisecond-level or even longer latency caused by software sampling, calculation, and instruction execution, fundamentally ensuring the immediacy of switching actions.

[0033] In this application, the specific hardware structure of the charging switching control circuit 300 can include discrete components, analog integrated circuits, or dedicated power management chips, etc., as long as they can achieve the above-mentioned automatic mutual exclusion switching function based on hardware voltage sensing, they all fall within the protection scope of this application. Through this pure hardware-level automatic seamless switching architecture, it is ensured that in extreme conditions such as sudden power outages, the backup battery 200 can immediately take over the load, ensuring that the charging process of the lithium battery 10 to be charged is uninterrupted, significantly improving the operational reliability of the battery swapping cabinet and the user experience.

[0034] In some embodiments, combined with Figure 2 The charging switching control circuit 300 includes a first NPN transistor Q1 and a second NPN transistor Q2. The base of the first NPN transistor Q1 is electrically connected to the output terminal of the main power module 100, the emitter of the first NPN transistor Q1 is grounded, and the collector of the first NPN transistor Q1 is electrically connected to a first switching device 410 to control the switching on and off of the first switching device 410. The base of the second NPN transistor Q2 is electrically connected to the output terminal of the main power module 100, the emitter of the second NPN transistor Q2 is grounded, and the collector of the second NPN transistor Q2 is electrically connected to a second switching device 420 to control the switching on and off of the second switching device 420.

[0035] Combination Figure 1 and Figure 2 At this time, the conduction signal of the first switching device 410 is low, and the conduction signal of the second switching device 420 is high. When the main power module 100 outputs a normal DC voltage, this voltage is applied to the bases of the first NPN transistor Q1 and the second NPN transistor Q2, causing them to enter a saturation conduction state. The collector potential is pulled down to near a low level, thus turning on the first switching device 410 and turning off the second switching device 420. Conversely, when the main power module 100 is powered off or the voltage drops below the turn-on threshold of the first NPN transistor Q1 and the second NPN transistor Q2, the first NPN transistor Q1 and the second NPN transistor Q2 automatically exit the conduction region and enter the cutoff state, with the collector exhibiting a high resistance state. Thus, the first switching device 410 turns off, and the second switching device 420 turns on. This direct response mechanism based on the physical characteristics of semiconductor PN junctions requires no software intervention or digital logic operations, fundamentally ensuring the real-time and deterministic nature of state detection and avoiding the risk of control failure due to processor malfunctions.

[0036] In one embodiment, combined with Figure 2The output terminal of the main power module 100 is grounded via a first resistor R1 and a second resistor R2 connected in series. The base of the first NPN transistor Q1 is electrically connected to the voltage divider node of the first resistor R1 and the second resistor R2. The resistor voltage divider network formed by the first resistor R1 and the second resistor R2 not only converts the high-voltage DC output from the main power module 100 into a safe bias voltage suitable for the base of the first NPN transistor Q1, but also allows for precise setting of the conduction threshold (typically about 0.7V) of the first NPN transistor Q1 by adjusting the resistance ratio of the first resistor R1 and the second resistor R2.

[0037] In one embodiment, combined with Figure 2 The collector of the first NPN transistor Q1 is electrically connected to the first switching device 410 through the third resistor R3. The third resistor R3 limits the peak discharge current of the first NPN transistor Q1 to the first switching device 410 at the moment of conduction, avoiding voltage spikes or oscillations caused by excessive current change rate. It also prevents the collector current of the first NPN transistor Q1 from exceeding its maximum allowable power dissipation, thus extending the device's lifespan.

[0038] In one embodiment, combined with Figure 2 The base of the second NPN transistor Q2 is grounded through the first capacitor C1. The first capacitor C1 suppresses potential voltage overshoot or high-frequency glitches that may occur when the main power module 100 is powered on. Specifically, in the initial stage of power-on, even if the voltage output by the main power module 100 momentarily exceeds the theoretical conduction threshold of the second NPN transistor Q2, the base potential of the second NPN transistor Q2 will be clamped at a lower level and slowly rise because the voltage across the first capacitor C1 cannot change abruptly. Only when the voltage output by the main power module 100 remains stable above the preset threshold will the second NPN transistor Q2 truly conduct, thereby effectively avoiding frequent accidental switching of the backup battery 200 due to grid fluctuations or power-on surges, ensuring power supply continuity.

[0039] Specifically, the base of the second NPN transistor Q2 is grounded through the eleventh resistor R11. The eleventh resistor R11 and the first capacitor C1 determine the delay window. The second NPN transistor Q2 will only turn on when the voltage output by the main power module 100 remains stable for a period of time exceeding this delay window.

[0040] In one embodiment, combined with Figure 2The collector of the second NPN transistor Q2 is electrically connected to the second switching device 420 through the fourth resistor R4. The fourth resistor R4 limits the peak discharge current of the second NPN transistor Q2 to the second switching device 420 at the moment of conduction, avoiding voltage spikes or oscillations caused by excessive current change rate. It also prevents the collector current of the second NPN transistor Q2 from exceeding its maximum allowable power dissipation, thus extending the device's lifespan.

[0041] In some embodiments, combined with Figure 2 In order to ensure that the conduction signals of the first switching device 410 and the second switching device 420 are both at a low level, the charging switching control circuit 300 also includes a third NPN transistor Q3. The base of the third NPN transistor Q3 is electrically connected to the output terminal of the main power module 100, the collector of the third NPN transistor Q3 is electrically connected to the base of the second NPN transistor Q2, and the emitter of the third NPN transistor Q3 is grounded.

[0042] Based on this, when the main power module 100 is powered on and the voltage reaches the conduction threshold of the third NPN transistor Q3, the third NPN transistor Q3 enters the saturation conduction state preferentially or synchronously with the second NPN transistor Q2. At this time, the low-impedance path between the collector and emitter of the third NPN transistor Q3 will force the base of the second NPN transistor Q2 to be pulled down to near a low level. Since the base of the second NPN transistor Q2 is actively clamped by the third NPN transistor Q3, even if the main voltage meets the conduction condition of the second NPN transistor Q2, the second NPN transistor Q2 cannot obtain sufficient base drive current and is forced to remain in the off state, thereby ensuring that the second switching device 420 is absolutely turned off when the main power module 100 is normal. This hardware-level forced interlocking mechanism completely eliminates the risk of the first NPN transistor Q1 and the second NPN transistor Q2 being mistakenly turned on simultaneously due to device parameter discreteness, temperature drift, or transient interference at the physical level. Compared with relying solely on software logic judgment or single-transistor self-locking schemes, it has higher determinism and security.

[0043] In one embodiment, the output of the main power module 100 is grounded via a series connection of a fifth resistor R5 and a sixth resistor R6, and the base of the third NPN transistor Q3 is electrically connected to the voltage divider node of the fifth resistor R5 and the sixth resistor R6. The resistor divider network formed by the fifth resistor R5 and the sixth resistor R6 not only converts the high-voltage DC output from the main power module 100 into a safe bias voltage suitable for the base of the third NPN transistor Q3, but also allows for precise setting of the conduction threshold of the third NPN transistor Q3 by adjusting the resistance ratio of the fifth resistor R5 and the sixth resistor R6.

[0044] Specifically, the charging switching control circuit 300 also includes a twelfth resistor R12. One end of the twelfth resistor R12 is electrically connected to the positive terminal of the backup battery 200, and the other end is connected to the collector of the third NPN transistor Q3 and the base of the second NPN transistor Q2. When the main power module 100 is powered on and the third NPN transistor Q3 is saturated and conducting, the twelfth resistor R12 acts as a current limiter, limiting the current flowing from the positive terminal of the backup battery 200 into the collector of the third NPN transistor Q3, thus preventing the third NPN transistor Q3 from being damaged by overcurrent. When the main power module 100 is powered off and the third NPN transistor Q3 is turned off, the twelfth resistor R12 works in conjunction with the eleventh resistor R11 to provide a pull-up drive current to the base of the second NPN transistor Q2, preventing the base of the second NPN transistor Q2 from being in a floating state and ensuring that the second NPN transistor Q2 is reliably turned on.

[0045] In this application, the first switching device 410 and the second switching device 420 are power switching elements with electrically controlled switching capabilities. Specific devices can be any one or more combinations of power MOSFETs, IGBTs, solid-state relays, or electromagnetic relays. For example, in scenarios requiring extremely high switching speeds, a low-on-resistance power MOSFET is preferred to achieve microsecond-level response; while in cost-sensitive scenarios with lower switching frequencies, a high-capacity relay can also be used.

[0046] In some embodiments, combined with Figure 2 The first switching device 410 includes a first PMOS transistor Q4. The source of the first PMOS transistor Q4 is electrically connected to the output terminal of the main power module 100, the drain of the first PMOS transistor Q4 is electrically connected to the lithium battery 10 to be charged, and the gate of the first PMOS transistor Q4 is electrically connected to the charging switching control circuit 300. Based on this, when the first PMOS transistor Q4 is turned off, even if the voltage on the side of the lithium battery 10 to be charged or the backup battery 200 is higher than the output voltage of the main power module 100, the parasitic diode inside the first PMOS transistor Q4 is in a reverse cutoff state, effectively preventing current from flowing back into the main power module 100 and causing device damage.

[0047] In one embodiment, the second switching device 420 includes a second PMOS transistor Q5. The source of the second PMOS transistor Q5 is electrically connected to the positive terminal of the backup battery 200, the drain of the second PMOS transistor Q5 is electrically connected to the lithium battery 10 to be charged, and the gate of the second PMOS transistor Q5 is electrically connected to the charging switching control circuit 300. Therefore, when the second PMOS transistor Q5 is turned off, even if the voltage on the side of the lithium battery 10 to be charged or the backup battery 200 is lower than the output voltage of the main power module 100, the parasitic diode inside the second PMOS transistor Q5 is in a reverse cutoff state, effectively preventing current from flowing back into the backup battery 200 and causing device damage.

[0048] In one embodiment, combined with Figure 2 The lithium battery swapping cabinet includes a first diode D1. The anode of the first diode D1 is connected to the source of the second PMOS transistor Q5, and the cathode of the first diode D1 is electrically connected to the gate of the first PMOS transistor Q4 through a seventh resistor R7. When the main power module 100 is normally powered, the voltage output by the main power module 100 is usually higher than or equal to the voltage output by the backup battery 200. The first diode D1 is cut off because the anode potential is lower than the cathode potential, and it does not affect the normal drive logic. However, when the main power module 100 experiences a power outage or voltage drop, and the voltage of the backup battery 200 is higher than the residual voltage of the main power module 100, the first diode D1 is forward-biased, coupling the high potential of the backup battery 200 to the gate of the first PMOS transistor Q4 through the seventh resistor R7. Since the turn-off condition of the PMOS transistor is that the gate-source voltage is close to zero or positive, this coupling action can quickly raise the gate potential of the first PMOS transistor Q4, forcibly eliminate the residual negative charge on the gate capacitor, thereby significantly shortening the turn-off delay time of the first PMOS transistor Q4. It cleverly utilizes the energy of the backup battery 200 itself to accelerate the turn-off of the main circuit switch, ensuring the speed and smoothness of the switching process.

[0049] In one embodiment, the gate of the first PMOS transistor Q4 is electrically connected to the output terminal of the main power module 100 through an eighth resistor R8. During the power-on initialization phase of the main power module 100, when the charging switching control circuit 300 is not yet operating stably, or in extreme cases where a failure of the charging switching control circuit 300 leads to the loss of the drive signal, the eighth resistor R8 clamps the gate of the first PMOS transistor Q4 to the output terminal of the main power module 100, so that the first PMOS transistor Q4 naturally remains in the off state. This fundamentally eliminates the risk of a short circuit and explosion caused by the simultaneous charging of the main power module 100 and the backup battery 200 due to control failure, ensuring that a safe electrical isolation state can be maintained under any abnormal conditions, greatly improving the robustness of the lithium battery swapping cabinet in long-term operation.

[0050] In one embodiment, the gate of the second PMOS transistor Q5 is electrically connected to the positive terminal of the backup battery 200 via the ninth resistor R9. Similarly, in the extreme case where a failure of the charging switching control circuit 300 causes the drive signal to be lost, the ninth resistor R9 will clamp the gate of the second PMOS transistor Q5 to the output terminal of the backup battery 200, so that the second PMOS transistor Q5 naturally remains in the off state.

[0051] In one embodiment, the lithium battery swapping cabinet further includes a resistor-capacitor (RC) absorption branch 610. The RC absorption branch 610 includes a second diode D2 and a tenth resistor R10. The high-voltage input terminal of the second diode D2 is connected to the positive terminal of the backup battery 200, the low-voltage discharge terminal of the second diode D2 is connected to one end of the tenth resistor R10, and the other end of the tenth resistor R10 is connected to the negative terminal of the backup battery 200. The RC absorption branch 610 is connected in parallel across the two ends of the backup battery 200 to suppress transient overvoltages caused by parasitic inductance in the circuit or sudden load changes. During steady-state operation, since the terminal voltage of the backup battery 200 is lower than the reverse breakdown voltage or forward conduction threshold of the second diode D2 (depending on whether it is a Zener diode or a rectifier diode), this branch is in a high-impedance cutoff state and will not generate additional static power consumption. Only when the voltage spike generated at the moment of switching exceeds the preset safety threshold will the second diode D2 quickly conduct, guiding the transient high voltage to the tenth resistor R10 for energy dissipation, thereby clamping the voltage of the positive terminal of the backup battery 200 to ground within a safe range, effectively preventing the second PMOS transistor Q5 from being damaged due to drain-source overvoltage.

[0052] In one embodiment, the lithium battery swapping cabinet further includes a capacitor filter branch 620, which is connected in parallel with the RC absorption branch 610. The capacitor filter branch 620 includes at least two filter capacitors C2 connected in series. On the one hand, the series connection makes the total withstand voltage equal to the sum of the withstand voltages of each individual capacitor, which can effectively share the high voltage stress on the DC bus and avoid the risk of a single filter capacitor C2 experiencing lifespan degradation or breakdown failure due to long-term exposure to near-limit voltage, thus significantly improving the reliability of devices in high-voltage application scenarios. On the other hand, the equivalent series resistance (ESR) and equivalent series inductance (ESL) characteristics change after multiple filter capacitors C2 are connected in series. Combined with the aforementioned RC absorption branch 610, a wider bandwidth noise filtering network can be formed, which not only filters out low-frequency ripple but also absorbs high-frequency switching noise.

[0053] In one specific embodiment, combined with Figure 2 The specific circuit structure shown provides a detailed explanation of the seamless switching timing when the main power module 100 experiences a power outage.

[0054] During the steady-state phase of normal power supply of the main power module 100, the output voltage of the main power module 100 remains above the preset threshold. At this time, both the first NPN transistor Q1 and the third NPN transistor Q3 are in a deep saturation conduction state. The conduction of the first NPN transistor Q1 pulls the gate potential of the first PMOS transistor Q4 down to near ground potential, so that its gate-source voltage meets the conduction condition, and the power supply path of the main power module 100 is unobstructed; at the same time, the conduction of the third NPN transistor Q3 forces the base of the second NPN transistor Q2 to be clamped at a low level, so that the second NPN transistor Q2 is reliably turned off, thereby ensuring that the gate of the second PMOS transistor Q5 is pulled up to the positive potential of the backup battery 200 by the ninth resistor R9 and remains off. In this state, the lithium battery 10 to be charged is completely powered by the main power module 100, the backup battery 200 is in standby state, the circuit power consumption is extremely low and there is no risk of circulating current.

[0055] When the main power module 100 experiences an unexpected power outage or a sudden voltage drop, the current flowing through the first resistor R1 and the fifth resistor R5 decreases as the output voltage of the main power module 100 drops. This results in insufficient base drive current for the first NPN transistor Q1 and the third NPN transistor Q3, causing them to gradually exit the saturation region. Due to the pull-up effect of the eighth resistor R8, the gate potential of the first PMOS transistor Q4 begins to rise with the main voltage. The first PMOS transistor Q4 then enters the linear region and eventually turns off, cutting off the power supply path of the main power module 100. At the same time, although the clamping effect of the third NPN transistor Q3 on the base of the second NPN transistor Q2 weakens as the third NPN transistor Q3 exits saturation, the first capacitor C1 is connected in parallel with the base of the second NPN transistor Q2. The voltage across the first capacitor C1 cannot change abruptly, and its charging process forms an inherent delay window. This means that in the initial stage of the output voltage drop of the main power module 100, the base potential of the second NPN transistor Q2 will not immediately rise to the conduction threshold, thereby effectively avoiding the second NPN transistor Q2 from being mis-turned on due to voltage ripple or transient interference.

[0056] As the output voltage of the main power module 100 further drops below the preset threshold and the first capacitor C1 completes charging, the base potential of the second NPN transistor Q2 reaches the conduction threshold. The second NPN transistor Q2 quickly saturates and conducts, pulling the gate of the second PMOS transistor Q5 low. The second PMOS transistor Q5 then conducts, and the backup battery 200 officially takes over the load power supply. It should be noted that at the instant between the turn-off of the first PMOS transistor Q4 and the turn-on of the second PMOS transistor Q5, if the voltage of the backup battery 200 is higher than the residual voltage of the main power module 100, the unidirectional coupling branch formed by the first diode D1 and the seventh resistor R7 will automatically engage. This branch utilizes the high potential of the backup battery 200 to conduct forward through the first diode D1, injecting charge into the gate of the first PMOS transistor Q4 via the seventh resistor R7. This accelerates the elimination of the residual negative voltage on the gate-source capacitance of the first PMOS transistor Q4, forcing the first PMOS transistor Q4 to turn off completely with a steeper slope. This not only shortens the switching dead time but also fundamentally eliminates the phenomenon of brief shoot-through or current reverse flow between the main power module 100 and the backup battery 200 caused by the tailing of the first PMOS transistor Q4's turn-off, thus ensuring the safety of the power devices.

[0057] When the main power module 100 resumes normal power supply, due to the independent design of the bias network of the third NPN transistor Q3 and its typically high sensitivity, the third NPN transistor Q3 will resume conduction before the first NPN transistor Q1. Once the third NPN transistor Q3 conducts, it immediately pulls the base of the second NPN transistor Q2 down to ground potential, forcing the second NPN transistor Q2 to turn off and turning off the second PMOS transistor Q5. Subsequently, as the voltage of the main power module 100 stabilizes, the first NPN transistor Q1 turns on again and drives the first PMOS transistor Q4 to turn on. This interlocking timing, naturally formed by the hardware topology, ensures that there is no risk of a short circuit due to simultaneous conduction of both power supplies under any recovery condition. Throughout the switching process, thanks to the microsecond-level response speed of the pure hardware circuitry and the precise matching of the RC parameters at each node, the voltage drop at the output terminal Vout was controlled within a very small range, and the duration of the drop was far less than the undervoltage reset threshold of the battery management system (BMS) inside the lithium battery 10 to be charged. The switching process was smooth and imperceptible, without any observable power interruption or significant surge current impact.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium battery swapping cabinet, characterized in that, It includes a main power module, a backup battery, and a charging switching control circuit. The main power module is used to connect to the mains power and output a DC power supply voltage. The main power module supplies power to the lithium battery to be charged through a first switching device, and the backup battery supplies power to the lithium battery to be charged through a second switching device. The charging switching control circuit is electrically connected to the main power module, the first switching device, and the second switching device, respectively. When the charging switching control circuit detects that the main power module is powered on, it controls the first switching device to be turned on and the second switching device to be turned off. When the charging switching control circuit detects that the main power module is powered off, it controls the first switching device to be turned off and the second switching device to be turned on.

2. The lithium battery swapping cabinet according to claim 1, characterized in that: The charging switching control circuit includes a first NPN transistor and a second NPN transistor. The base of the first NPN transistor is electrically connected to the output terminal of the main power module, the emitter of the first NPN transistor is grounded, and the collector of the first NPN transistor is electrically connected to the first switching device to control the switching on and off of the first switching device. The base of the second NPN transistor is electrically connected to the output terminal of the main power module, the emitter of the second NPN transistor is grounded, and the collector of the second NPN transistor is electrically connected to the second switching device to control the on / off state of the second switching device.

3. The lithium battery swapping cabinet according to claim 2, characterized in that: The output terminal of the main power module is grounded through a first resistor and a second resistor connected in series, and the base of the first NPN transistor is electrically connected to the voltage divider node of the first resistor and the second resistor. The collector of the first NPN transistor is electrically connected to the first switching device through a third resistor; The base of the second NPN transistor is grounded through the first capacitor; The collector of the second NPN transistor is electrically connected to the second switching device through the fourth resistor.

4. The lithium battery swapping cabinet according to claim 2, characterized in that: The charging switching control circuit also includes a third NPN transistor, the base of which is electrically connected to the output terminal of the main power module, the collector of which is electrically connected to the base of the second NPN transistor, and the emitter of which is grounded.

5. The lithium battery swapping cabinet according to claim 4, characterized in that: The output terminal of the main power module is grounded via a fifth and a sixth resistor connected in series, and the base of the third NPN transistor is electrically connected to the voltage divider node of the fifth and the sixth resistors.

6. The lithium battery swapping cabinet according to claim 1, characterized in that: The first switching device includes a first PMOS transistor, the source of which is electrically connected to the output terminal of the main power module, the drain of which is electrically connected to the lithium battery to be charged, and the gate of which is electrically connected to the charging switching control circuit. The second switching device includes a second PMOS transistor, the source of which is electrically connected to the positive terminal of the backup battery, the drain of which is electrically connected to the lithium battery to be charged, and the gate of which is electrically connected to the charging switching control circuit.

7. The lithium battery swapping cabinet according to claim 6, characterized in that: The lithium battery swapping cabinet includes a first diode, the anode of the first diode is connected to the source of the second PMOS transistor, and the cathode of the first diode is electrically connected to the gate of the first PMOS transistor through a seventh resistor.

8. The lithium battery swapping cabinet according to claim 6, characterized in that: The gate of the first PMOS transistor is electrically connected to the output terminal of the main power module through an eighth resistor. The gate of the second PMOS transistor is electrically connected to the positive terminal of the backup battery through the ninth resistor.

9. The lithium battery swapping cabinet according to any one of claims 1 to 8, characterized in that: The lithium battery swapping cabinet also includes a resistor-capacitor absorption branch, which includes a second diode and a tenth resistor. The high-voltage input terminal of the second diode is connected to the positive terminal of the backup battery, the low-voltage discharge terminal of the second diode is connected to one end of the tenth resistor, and the other end of the tenth resistor is connected to the negative terminal of the backup battery.

10. The lithium battery swapping cabinet according to claim 9, characterized in that: The lithium battery swapping cabinet also includes a capacitor filter branch, which is connected in parallel with the resistor-capacitor absorption branch, and the capacitor filter branch includes at least two filter capacitors connected in series.

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