Pre-charging device and electronic device

Abstract

This application provides a pre-charging device applied to an electronic device containing a capacitive load, comprising: a power supply unit; an output interface electrically connected to a load unit of the electronic device, the load unit including a capacitive load; a pre-charging branch containing a high-energy resistor, the pre-charging branch being electrically connected between the power supply unit and the output interface, used to connect the power supply unit and the output interface according to a first external control signal, so that the power supply unit performs current-limited pre-charging of the capacitive load through the pre-charging branch; and a main power supply branch electrically connected between the power supply unit and the output interface, connected in parallel with the pre-charging branch, used to connect the power supply unit and the output interface and bypass the pre-charging branch according to a second external control signal after the pre-charging branch has completed pre-charging of the capacitive load, so that the power supply unit supplies power to the load unit through the main power supply branch, avoiding the huge surge current generated by directly conducting the main power supply branch when the capacitor is not charged, and protecting downstream devices from current stress impact.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a pre-charging device and electronic device. Background Technology

[0002] High-power electronic devices, such as robotic equipment, typically feature high-power main control modules, motor drivers, and multiple articulated motors. Their power supply buses and articulated motor buses generally employ a capacitive load architecture with multiple large-capacity electrolytic capacitors connected in parallel, resulting in a large overall equivalent capacitance. Upon power-up, the uncharged electrolytic capacitors are nearly short-circuited, causing a sudden and dramatic change in the circuit current, with peak values ​​reaching 2 to 2.828 times the rated operating current, forming a starting inrush current. This inrush current can easily cause relay contact erosion, breakdown damage to downstream power electronic components, and accelerate the aging and degradation of various components, shortening the overall lifespan of the equipment. Therefore, the industry commonly uses resistive pre-charge circuits with short-term overload capability and high peak power tolerance to achieve smooth pre-charging of the capacitive load and suppress power-up inrush.

[0003] Current pre-charging solutions are mostly concentrated at the output end of the battery management system (BMS) or in series with a power resistor between the power supply and the back-end load. They rely on the battery's built-in pre-charging circuit to perform current-limiting pre-charging of the back-end circuit, thereby smoothing out power-on current spikes. However, this traditional pre-charging architecture has obvious limitations. It can only achieve pre-charging of local circuits and cannot cover core load branches such as motor drivers and articulated motors. This can easily cause the BMS pre-charging circuit to fail, resulting in a significant decrease in the overall pre-charging protection effect. It cannot effectively avoid impact damage to relays and switching devices, and it can also cause long-term overload heating of the power resistor, leading to resistor aging and burnout, and decreased circuit stability. It is difficult to meet the reliable power-on protection requirements of the robot's entire load chain. Summary of the Invention

[0004] The purpose of this application is to provide a pre-charging device and electronic device that can solve the above-mentioned problems.

[0005] One aspect of this application provides a pre-charging device applied to an electronic device containing a capacitive load, comprising: a power supply unit; an output interface electrically connected to a load unit of the electronic device, the load unit including the capacitive load; a pre-charging branch containing a high-energy resistor, the pre-charging branch being electrically connected between the power supply unit and the output interface, for connecting the power supply unit and the output interface according to a first external control signal, so that the power supply unit performs current-limited pre-charging of the capacitive load through the pre-charging branch; and a main power supply branch electrically connected between the power supply unit and the output interface, connected in parallel with the pre-charging branch, for connecting the power supply unit and the output interface and bypassing the pre-charging branch according to a second external control signal after the pre-charging branch has completed pre-charging of the capacitive load, so that the power supply unit supplies power to the load unit through the main power supply branch, wherein the first external control signal and the second external control signal are independent of each other, and the first external control signal and the second external control signal are enabled according to a preset timing rule.

[0006] Preferably, the preset timing rule is as follows: when the electronic device is powered on, the first external control signal is enabled first; after the pre-charging branch completes the pre-charging of the capacitive load, the second external control signal is enabled; when the electronic device is powered off, the second external control signal fails first or the first external control signal and the second external control signal fail simultaneously.

[0007] Preferably, the pre-charge branch includes: the high-energy resistor, one end of which is electrically connected to the power supply unit; a first electronic switch, including a first terminal, a second terminal, and a control terminal, wherein the first terminal of the first electronic switch is electrically connected to the other terminal of the high-energy resistor, and the second terminal of the first electronic switch is electrically connected to the output interface; a first voltage divider network, including a first resistor and a second resistor, wherein one end of the first resistor is electrically connected to the other terminal of the high-energy resistor, and the other end of the first resistor is electrically connected to the control terminal of the first electronic switch and one end of the second resistor; a second electronic switch, including a first terminal, a second terminal, and a control terminal, wherein the first terminal of the second electronic switch is grounded, and the second terminal of the second electronic switch is electrically connected to the other terminal of the second resistor; and a second voltage divider network, including a third resistor and a fourth resistor, wherein one end of the third resistor is electrically connected to the control terminal of the second electronic switch and one end of the fourth resistor, the other end of the third resistor is grounded, and the other end of the fourth resistor is connected to the first external control signal.

[0008] Preferably, when the first external control signal is enabled, the first external control signal controls the second electronic switch to be turned on; when the second electronic switch is turned on, the second resistor is grounded to enable the control terminal of the first electronic switch, and the first electronic switch is turned on; when the first electronic switch is turned on, the pre-charge branch is turned on, and the power supply unit performs current-limited charging of the capacitive load through the high-energy resistor.

[0009] Preferably, when the first external control signal is not enabled, both the second electronic switch and the first electronic switch are in the off state, and the precharge branch is automatically in the isolated off state; when the first external control signal is enabled and then fails, the control terminal of the second electronic switch is pulled down to ground through the third resistor, the second electronic switch is turned off, and then the first electronic switch is turned off, forcibly disconnecting the power supply unit from the load unit.

[0010] Preferably, the main power supply branch includes: a third electronic switch, including a first terminal, a second terminal, and a control terminal, wherein the first terminal of the third electronic switch is electrically connected to the power supply unit, and the second terminal of the third electronic switch is electrically connected to the output interface; a third voltage divider network, including a fifth resistor and a sixth resistor, wherein one end of the fifth resistor is electrically connected to the first terminal of the third electronic switch, and the other end of the fifth resistor is electrically connected to the control terminal of the third electronic switch and one end of the sixth resistor; a fourth electronic switch, including a first terminal, a second terminal, and a control terminal, wherein the first terminal of the fourth electronic switch is grounded, and the second terminal of the fourth electronic switch is electrically connected to the other end of the sixth resistor; and a fourth voltage divider network, including a seventh resistor and an eighth resistor, wherein one end of the seventh resistor is electrically connected to the control terminal of the fourth electronic switch and one end of the eighth resistor, the other end of the seventh resistor is grounded, and the other end of the eighth resistor is connected to the second external control signal.

[0011] Preferably, the difference between the conduction response time of the second electronic switch and the conduction response time of the fourth electronic switch is less than a preset time.

[0012] Preferably, after the pre-charge branch completes the pre-charging of the capacitive load and the second external control signal is enabled, the second external control signal controls the fourth electronic switch to turn on; when the fourth electronic switch is turned on, the sixth resistor is grounded to enable the control terminal of the third electronic switch, and the third electronic switch turns on; when the third electronic switch is turned on, the main power supply branch is turned on, the pre-charge branch is bypassed, and the power supply unit supplies power to the load unit through the main power supply branch.

[0013] Preferably, when the second external control signal is not enabled, both the third and fourth electronic switches are in the off state, and the main power supply branch is automatically in the isolated off state; when the second external control signal fails after being enabled, the control terminal of the fourth electronic switch is pulled down to ground through the seventh resistor, the fourth electronic switch is disconnected, and then the third electronic switch is controlled to disconnect, forcibly disconnecting the power supply unit from the load unit.

[0014] One aspect of this application provides an electronic device, including: The pre-charging device described in any of the above claims; A controller is used to output a first external control signal and a second external control signal to the pre-charging device to control the pre-charging device.

[0015] Compared to existing technologies, the pre-charging device and electronic equipment proposed in this application include a pre-charging branch containing a high-energy resistor and a main power supply branch. The pre-charging branch containing the high-energy resistor is first turned on according to a first external control signal, thereby connecting the power supply unit and the output interface. This allows the power supply unit to perform current-limited pre-charging of the capacitive load electrically connected to the output interface through the pre-charging branch. After the pre-charging branch completes the pre-charging of the capacitive load, the main power supply branch is turned on according to a second external control signal to connect the power supply unit and the output interface, allowing the power supply unit to supply power to the load unit through the main power supply branch. Therefore, in the initial stage of power-on, the main power supply branch is in a turned-off state, and the only path for surge current is the pre-charging branch containing the high-energy resistor. The high-energy resistor preferentially carries and dissipates all the impact energy during the capacitor charging process. After pre-charging is completed, the main power supply branch is turned on to bypass the high-energy resistor. Thereafter, almost all the steady-state operating current flows through the main power supply branch, avoiding the huge surge current generated by directly turning on the main power supply branch when the capacitor is not charged, and protecting the downstream driver and related devices from current stress impact.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic diagram of a pre-charging device according to Embodiment 1 of this application is shown.

[0019] Figure 2 A circuit diagram of a pre-charging device according to Embodiment 2 of this application is shown schematically.

[0020] Explanation of key component symbols: Pre-charging device 1 Power supply unit 10 Output interface 20 Pre-charge branch 30 Main power supply branch 40 High-energy resistor Rr First external control signal CONCTRL1_SIGNAL Second external control signal CONCTRL2_SIGNAL First electronic switch - Fourth electronic switch Q1-Q4 First voltage divider network - Fourth voltage divider network V1-V4 First resistor - Eighth resistor R1-R8 Detailed Implementation The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this application more thorough and complete. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "connected," and "electrically connected" should be interpreted broadly. For example, it can refer to a direct connection or an indirect connection through an intermediate medium, or it can refer to the internal connection of two elements. It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element present.

[0023] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0024] Example 1 Figure 1 A schematic diagram of a pre-charging device 1 according to Embodiment 1 of this application is shown. This pre-charging device 1 is mainly used in high-power electronic devices, such as robots. Figure 1 As shown, the pre-charging device 1 includes a power supply unit 10, an output interface 20, a pre-charging branch 30, and a main power supply branch 40.

[0025] This embodiment applies a pre-charging device 1 based on a high-energy resistor Rr to a robot, with the power supply unit 10 described using a battery as an example. The output interface 20 is electrically connected to the load unit (not shown) of the electronic device. The load unit depends on the type of electronic device and may include, but is not limited to, a high-power main control module, a motor driver, and multiple articulated motors, as well as capacitive loads. The capacitive load can be a capacitive load architecture consisting of multiple large-capacity electrolytic capacitors connected in parallel on the articulated motor bus. The pre-charging branch 30, containing a high-energy resistor Rr, is electrically connected between the power supply unit 10 and the output interface 20. It is used to connect the power supply unit 10 and the output interface 20 according to the first external control signal CONCTRL1_SIGNAL. That is, the first external control signal CONCTRL1_SIGNAL controls the pre-charging branch 30 to conduct, allowing the power supply unit 10 to perform current-limited pre-charging of the capacitive load through the pre-charging branch 30. The main power supply branch 40 is electrically connected between the power supply unit 10 and the output interface 20. The main power supply branch 40 is connected in parallel with the pre-charge branch 30. After the pre-charge branch 30 completes pre-charging of the capacitive load, it connects the power supply unit 10 and the output interface 20 according to the second external control signal CONCTRL2_SIGNAL. The second external control signal CONCTRL2_SIGNAL controls the main power supply branch 40 to conduct, allowing the power supply unit 10 to supply power to the load unit through the main power supply branch 40. The first external control signal CONCTRL1_SIGNAL and the second external control signal CONCTRL2_SIGNAL are independent of each other and represent DC digital logic level signals output by an external controller, such as the main control unit of a robot.

[0026] In this application, the high-energy resistor Rr can be understood as a pulse-resistant resistor capable of withstanding pulse energy surges during the pre-charging process of a capacitive load. It can be matched with the capacitive load capacity through its resistance value, pulse energy tolerance value, packaging form, and heat dissipation conditions.

[0027] In this embodiment, the output interface 20 serves as a unified power output interface, converging the outputs of the pre-charge branch 30 and the main power supply branch 40 onto the same interface. This design allows the pre-charge device 1 based on the high-energy resistor Rr of this application to simultaneously provide current-limited pre-charge current and steady-state operating current to the load unit, i.e., multiple parallel joint motor drivers in the subsequent stage, through the output interface 20. This simplifies the wiring harness connection of the robot's electrical system, reduces the number of external terminals and the amount of on-site wiring work, and improves system integration and ease of installation.

[0028] In this embodiment, the pre-charging device 1 based on the high-energy resistor Rr automatically switches between standby mode, pre-charging mode, and pass-through mode through the combined control of the first external control signal CONCTRL1_SIGNAL and the second external control signal CONCTRL2_SIGNAL. The first external control signal CONCTRL1_SIGNAL and the second external control signal CONCTRL2_SIGNAL are enabled according to a preset timing rule. Specifically, when the electronic device is powered on, the first external control signal CONCTRL1_SIGNAL is enabled first. After the pre-charging branch 30 completes the pre-charging of the capacitive load, the second external control signal CONCTRL2_SIGNAL is enabled, and the main power supply branch 40 is turned on. When the electronic device is powered off, the second external control signal CONCTRL2_SIGNAL is deactivated first, or the first external control signal CONCTRL1_SIGNAL and the second external control signal CONCTRL2_SIGNAL are deactivated simultaneously, to prevent the high-energy resistor Rr from overheating due to prolonged power-on and to avoid incomplete power-off of the load unit. When neither the first external control signal CONCTRL1_SIGNAL nor the second external control signal CONCTRL2_SIGNAL is enabled, the pre-charging device 1 based on the high-energy resistor Rr is in standby mode. In standby mode, the power supply unit 10 is isolated from the load unit, achieving zero-power safe standby. When the first external control signal CONCTRL1_SIGNAL is enabled, the pre-charging branch 30 is turned on, and the pre-charging device 1 based on the high-energy resistor Rr enters pre-charging mode. In pre-charging mode, the high-energy resistor Rr is connected in series in the circuit to limit current charging, suppress surges, and protect the back-end circuits of the electronic device from surge impacts. After the pre-charging of the capacitive load is completed, when the second external control signal CONCTRL2_SIGNAL is enabled, the main power supply branch 40 is turned on, and the pre-charging device 1 based on the high-energy resistor Rr enters pass-through mode. In pass-through mode, the main power supply branch 40 bypasses the pre-charging branch 30, that is, bypasses the high-energy resistor Rr, to eliminate the extra power consumption during normal operation, and the power supply unit 10 provides low-loss power supply to the load unit.

[0029] In some embodiments, the pre-charge branch 30 completes the pre-charging of the capacitive load, which may include the voltage of the output interface 20 reaching a preset proportion of the output voltage of the power supply unit 10, or the pre-charge branch 30 being continuously conducted for a preset duration. The preset proportion may be 85% to 95%, and the preset duration may be determined based on the time constant formed by the high-energy resistor Rr and the capacitive load.

[0030] At the moment the robot is powered on, the bus capacitor of the robot's subsequent joint motors is effectively in a short-circuit state. If the capacitive load is not charged with current limiting through the pre-charge branch 30, but instead the main power supply branch 40 is directly connected, the circuit current can reach 2 to 2.828 times the rated value, which can easily burn out relay contacts or subsequent electronic components. In pre-charge mode, a high-energy resistor Rr is connected in series in the circuit. Its resistance characteristics suppress the peak charging current within a safe threshold, avoiding surge impact. Simultaneously, the high-energy resistor Rr dissipates the electrical energy during capacitor charging as Joule heat, causing the current to rise smoothly according to the RC exponential law, eliminating the instantaneous stress impact of sudden current changes on circuit components. The clear division of the three modes in this application makes the circuit behavior predictable and controllable, facilitating external controllers to perform state management and fault diagnosis of the pre-charge device 1 based on the high-energy resistor Rr. Furthermore, the power consumption and thermal characteristics of each mode are clearly defined, facilitating system-level thermal design.

[0031] In this embodiment, the resistance value of the high-energy resistor Rr ranges from 10Ω to 100Ω. The high-energy resistor Rr, in conjunction with the capacitive load, ensures that the pre-charge time constant τ = R × C falls between 0.1s and 1s, where R is the resistance value of the high-energy resistor Rr and C is the capacitance value of the capacitive load. This time constant ensures that the peak pre-charge current is effectively suppressed, while the lower limit prevents excessively long pre-charge times that could cause the robot to time out during power-on. A pulse energy tolerance value greater than 50J ensures that the high-energy resistor Rr can safely absorb the energy stored in the capacitor during a single pre-charge (e.g., approximately 1.15J of energy stored in a 48V / 1000μF system capacitor), and provides sufficient margin to handle the heat accumulation from repeated power-ons, preventing resistance drift or burnout due to thermal stress.

[0032] In one specific embodiment of this application, the high-energy resistor Rr can be a pulse-resistant resistor in an axially led cylindrical package, model 251AEC250KDS. The 251AEC250KDS model resistor is specifically designed for pulsed power applications, and its interface strength between the internal resistive paste and the ceramic substrate is optimized to withstand short-term high-temperature gradient changes without microcracks. The axially led cylindrical package provides a large surface area to volume ratio, which facilitates the rapid dissipation of heat generated during pre-charge to the surrounding environment through convection and radiation.

[0033] Example 2 Figure 2A schematic circuit diagram of a pre-charging device 1 according to Embodiment 1 of this application is shown. Based on Embodiment 1, in this embodiment, the pre-charging branch 30 includes a high-energy resistor Rr, a first electronic switch Q1, a first voltage divider network V1, a second electronic switch Q2, and a second voltage divider network V2.

[0034] One end of the high-energy resistor Rr is electrically connected to the power supply unit 10. The first electronic switch Q1 includes a first terminal, a second terminal, and a control terminal. The first terminal of the first electronic switch Q1 is electrically connected to the other end of the high-energy resistor Rr, and the second terminal of the first electronic switch Q1 is electrically connected to the output interface 20. The high-energy resistor Rr and the first terminal of the first electronic switch Q1 are connected by three parallel wires, which can effectively disperse the pulse current during the pre-charge stage, reduce the current density and temperature rise of a single wire, and improve the long-term operational reliability of the pre-charge branch 30. The first voltage divider network V1 includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is electrically connected to the other end of the high-energy resistor Rr, and the other end of the first resistor R1 is electrically connected to the control terminal of the first electronic switch Q1 and one end of the second resistor R2. The second electronic switch Q2 includes a first terminal, a second terminal, and a control terminal. The first terminal of the second electronic switch Q2 is grounded, and the second terminal of the second electronic switch Q2 is electrically connected to the other end of the second resistor R2. The second voltage divider network V2 includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is electrically connected to the control terminal of the second electronic switch Q2 and one end of the fourth resistor R4. The other end of the third resistor R3 is grounded, and the other end of the fourth resistor R4 is connected to the first external control signal CONCTRL1_SIGNAL.

[0035] When the first external control signal CONCTRL1_SIGNAL is enabled, the first external control signal CONCTRL1_SIGNAL controls the second electronic switch Q2 to turn on; when the second electronic switch Q2 is turned on, the second resistor R2 is grounded to enable the control terminal of the first electronic switch Q1, and the first electronic switch Q1 is turned on; when the first electronic switch Q1 is turned on, the pre-charge branch 30 is turned on, and the power supply unit 10 performs current-limited charging on the capacitive load through the high-energy resistor Rr.

[0036] When the first external control signal CONCTRL1_SIGNAL is not enabled, both the second electronic switch Q2 and the first electronic switch Q1 are in the off state, and the precharge branch 30 is automatically in the isolated off state. When the first external control signal CONCTRL1_SIGNAL is enabled and then fails, the control terminal of the second electronic switch Q2 is pulled down to ground through the third resistor R3, the second electronic switch Q2 is turned off, and then the first electronic switch Q1 is turned off, forcibly disconnecting the power supply unit 10 and the output interface 20, that is, forcibly disconnecting the power supply unit 10 and the load unit.

[0037] In this embodiment, the first electronic switch Q1 is a P-type MOS transistor and the second electronic switch Q2 is an N-type MOS transistor, but this is not a limitation. The first terminal of the first electronic switch Q1 and the second electronic switch Q2 is the source, the second terminal is the drain, and the control terminal is the gate.

[0038] In this embodiment, when MOSFET Q1 is turned on, it is connected in series with the high-energy resistor Rr to form a pre-charge circuit, which together limits the charging current of the capacitive load and protects the downstream circuit from surge impact. When MOSFET Q2 is turned on, the second resistor R2 is grounded through MOSFET Q2, making the gate potential of MOSFET Q1 lower than its source potential, thereby turning on MOSFET Q1; when MOSFET Q2 is turned off, the gate of MOSFET Q1 is pulled to a potential close to its source through the first resistor R1, thereby turning off MOSFET Q1. This structure can reduce the risk of false turn-on or oscillation caused by a floating gate.

[0039] In this embodiment, the on-resistance of MOSFET Q1 is less than 50mΩ. Specifically, the current flowing through MOSFET Q1 during the pre-charge phase is the current after current limiting, and its peak value can still reach several amperes. Controlling the on-resistance of MOSFET Q1 below 50mΩ can significantly reduce the power consumption and heat generation of MOSFET Q1 itself during the pre-charge process, avoiding the junction temperature of MOSFET Q1 exceeding the limit or thermal failure due to overheating. At the same time, it reduces the total voltage drop of the pre-charge circuit, ensuring that the capacitive load can be charged to a higher level close to the battery voltage, creating favorable conditions for the safe switching of the subsequent main power supply branch 40.

[0040] The gate drive signal of MOSFET Q1 is not a steep square wave, but a slowly rising waveform shaped by an RC network formed by the first resistor R1 and its own gate parasitic capacitance. This waveform makes the transition process of the MOSFET Q1 channel from cutoff to conduction smoother, effectively suppressing the drain current rise rate, thereby reducing the amplitude of electromagnetic radiation and conducted interference generated by the precharge circuit at the moment of switching, and improving the electromagnetic compatibility of the circuit in the complex electromagnetic environment of the robot control cabinet.

[0041] In this embodiment, frequent start-stop cycles of the robot's load unit, such as articulated motors, can cause transient fluctuations in the battery bus voltage. If the gate-source voltage of MOSFET Q1 lacks clamping protection, it may exceed the breakdown voltage limit of the MOSFET's gate oxide layer. This application uses a first voltage divider network composed of a first resistor R1 and a second resistor R2 to limit the gate-source voltage of MOSFET Q1 within a safe range (not exceeding ±20V). Even under peak bus voltage conditions, this effectively protects the gate oxide layer from overvoltage stress damage, preventing gate oxide layer degradation or permanent breakdown, thereby extending the lifespan and reliability of MOSFET Q1 under frequent robot start-stop conditions. In practical applications, the resistance ratio of the first resistor R1 to the second resistor R2 is limited to between 3:1 and 10:1, so that the bus voltage drawn from the connection node between the high-energy resistor Rr and the source of MOSFET Q1, after voltage division, generates a driving voltage adapted to the gate of MOSFET Q1 at the common node of the first resistor R1 and the second resistor R2. This ratio range ensures that under battery voltage fluctuations (such as undervoltage or full charge), the gate-source voltage of MOSFET Q1 is both higher than the threshold voltage Vgs(th) to ensure full conduction and lower than the gate breakdown voltage limit to prevent overvoltage damage.

[0042] The design of the resistance ratio of the first resistor R1 to the second resistor R2 balances drive reliability and safety: at the lowest operating point of the battery voltage, the gate voltage after voltage division is still more than 1.5 times higher than the threshold voltage of MOSFET Q1, ensuring that MOSFET Q1 is fully turned on and the channel resistance is minimized, avoiding overheating and damage to MOSFET Q1 due to insufficient drive causing it to operate in the amplification region; at the highest operating point of the battery voltage, the gate voltage does not exceed the safety limit of ±20V, protecting the gate oxide layer from overvoltage stress. Simultaneously, when MOSFET Q1 switches from off to on, the gate charge is released to ground through R2 and the Q2 conduction channel; when Q1 switches from on to off, the gate returns to a potential close to the source through R1. The resistance value of the second resistor R2 directly determines the RC discharge time constant, thus affecting the turn-off response speed of MOSFET Q1, ensuring the controllability and consistency of the turn-off process. The first resistor R1 and the second resistor R2 are connected in a voltage divider configuration to directly draw power from the power supply unit 10 to generate the gate drive signal for the MOSFET Q1. The gate voltage amplitude is proportional to the battery voltage. This linear following characteristic allows the circuit to adapt to changes in battery voltage without the need for an additional regulated power supply or driver IC. When the battery enters an undervoltage state due to discharge or load fluctuations, although the gate voltage decreases accordingly, the reasonable design of the voltage divider ratio still maintains a drive margin of more than 1.5 times higher than the threshold voltage of the MOSFET Q1. This ensures that the MOSFET Q1 can still conduct reliably under low voltage conditions, avoiding pre-charge function failure or abnormal overheating of the MOSFET due to insufficient drive.

[0043] The first resistor R1 and the second resistor R2 form a voltage divider pair, and the relative accuracy of their resistance values ​​directly affects the accuracy of the voltage division ratio. In practical applications, selecting resistors from the same batch and with the same temperature coefficient ensures that the resistance drift direction and amplitude are consistent when the ambient temperature changes and the resistors themselves generate heat, thus maintaining the stability of the voltage division ratio across the entire temperature range. Symmetrical placement on the PCB layout ensures that the two resistors undergo the same thermal path during reflow soldering, reducing initial resistance differences caused by thermal gradients. This material selection and layout strategy effectively suppresses voltage division ratio drift caused by temperature effects and process deviations, improving the consistency and long-term reliability of the gate drive voltage across circuit boards in mass production. The resistance accuracy of the first resistor R1 and the second resistor R2, at ±1% or ±5%, ensures the consistency and repeatability of the voltage division ratio across circuit boards in mass production, avoiding excessive gate drive voltage dispersion due to individual resistor deviations.

[0044] In this embodiment, MOSFET Q2 serves only as a static enable switch for the pre-charge branch 30. The signal received by its gate is a DC logic level that changes during power-up, rather than a high-frequency PWM or communication signal. Therefore, MOSFET Q2 does not need to have high-speed switching capability, and a low-cost, general-purpose small-signal MOSFET can be selected. At the same time, the low-speed switching characteristic means that the gate drive circuit is not sensitive to parasitic parameters and has low signal integrity requirements, further simplifying the PCB layout and peripheral circuit design, and reducing the overall cost and complexity of the solution. The gate threshold voltage of MOSFET Q2 is limited to the range of 1V~2.5V, so that the first external control signal CONCTRL1_SIGNAL (3.3V or 5V logic level) output by the external controller can reliably drive MOSFET Q2 to conduct after being divided by the third resistor R3 and the fourth resistor R4 of the second voltage divider network V2. This threshold voltage range ensures sufficient conduction under standard logic high level (gate voltage greater than the threshold with margin) and reliable turn-off of MOSFET Q2 under logic low level or floating state (gate voltage lower than the threshold), achieving direct compatibility with the I / O levels of common robot main control units without the need for additional level conversion circuits.

[0045] When the first external control signal CONCTRL1_SIGNAL fails to enable (i.e., when CONCTRL1_SIGNAL is deactivated), causing MOSFET Q2 to turn off, the drain and source of MOSFET Q2 are in a high-resistance state, and the conduction path between the second resistor R2 and the ground terminal is broken. The gate of MOSFET Q1 is pulled to a potential close to the source of MOSFET Q1 through the first resistor R1, causing MOSFET Q1 to turn off, thereby forcibly disconnecting the power supply unit 10 and the output interface 20 (making the pre-charge branch in an open state). Thus, the conduction of MOSFET Q1 is indirectly controlled by the first external control signal CONCTRL1_SIGNAL in two stages. The first external control signal CONCTRL1_SIGNAL and the power circuit of the pre-charge branch 30 form an isolation buffer through MOSFET Q2, and the external controller only needs to provide a low-current logic level to reliably drive it. When the first external control signal CONCTRL1_SIGNAL is unexpectedly lost due to loose wiring, poor interface contact, or main controller failure, the gate of MOSFET Q2 is automatically turned off via the third resistor R3, which in turn turns off MOSFET Q1, and the pre-charge branch 30 is automatically cut off. This turn-off-priority fault protection mechanism requires no software intervention, and the response speed is determined purely by hardware, effectively preventing safety hazards caused by the continuous heating of the high-energy resistor Rr when the control signal is abnormal.

[0046] In practical applications, MOSFET Q2 is positioned close to the input interface of the first external control signal CONCTRL1_SIGNAL. This ensures that the first external control signal CONCTRL1_SIGNAL reaches the gate of MOSFET Q2 via the shortest path, with the trace length controlled within 10mm. The short trace significantly reduces the loop area of ​​the signal circuit, lowering the risk of the trace acting as an antenna to receive high-frequency electromagnetic interference from motors and drivers inside the robot's electrical control cabinet. This prevents interference signals from superimposing on the gate of MOSFET Q2, causing false triggering and ensuring the accuracy and immunity of the enable signal. The source of MOSFET Q1 is routed on the PCB with separate Kelvin traces for the power current path and the gate drive reference ground path. This layout avoids the voltage drop across the common ground impedance caused by the large current during the pre-charge phase, thus preventing this voltage drop from superimposing on the gate drive signal and causing gate-source voltage fluctuations or oscillations. Separate traces ensure the purity and stability of the gate drive signal, reducing the risk of false turn-on or switching oscillations caused by common impedance coupling in MOSFET Q1, and improving circuit reliability under high-current switching conditions.

[0047] In this embodiment, the resistance ratio of the third resistor R3 and the fourth resistor R4 in the second voltage divider network is limited to between 1:1 and 5:1. This ensures that the effective level (3.3V or 5V) of the first external control signal CONCTRL1_SIGNAL, after being divided, generates a drive voltage at the common node of the third resistor R3 and the fourth resistor R4 that is compatible with the gate of the MOSFET Q2. This ratio range ensures that the gate drive voltage is both higher than the threshold voltage Vgs(th) (1V~2.5V) of the MOSFET Q2 to achieve full conduction, and lower than the gate breakdown voltage limit of the MOSFET Q2 to protect the gate oxide layer. Simultaneously, the voltage divider ratio design avoids stringent requirements on the amplitude of the external signal level, making the circuit compatible with both 3.3V and 5V mainstream logic level standards. The third resistor R3 is connected at one end to the gate of MOSFET Q2 and at the other end to ground. This ensures that when the first external control signal CONCTRL1_SIGNAL is invalid (low level or signal line disconnected), the third resistor R3 reliably pulls the gate potential of MOSFET Q2 to ground, guaranteeing that the gate-source voltage of MOSFET Q2 is zero and MOSFET Q2 remains off. This pull-down resistor constitutes the circuit's default safety state: the pre-charge branch 30 automatically enters an isolated off state when no explicit enable signal is received. When the external signal line is accidentally opened due to vibration, interface oxidation, or controller failure, the third resistor R3 prevents the gate of MOSFET Q2 from being left floating and accidentally turned on due to electromagnetic interference coupling, thus preventing continuous battery discharge or resistor overheating, achieving purely hardware-based fault safety protection.

[0048] In practical applications, both the third resistor R3 and the fourth resistor R4 are surface-mount packages and positioned close to the gate pin of the MOSFET Q2, minimizing the trace length between the second voltage divider network V2 and the gate of the MOSFET Q2. Short traces reduce the parasitic inductance and loop area of ​​the gate drive circuit, lowering the risk of external electromagnetic interference coupled through the traces, and also reducing the potential resonance tendency caused by the gate input capacitance and parasitic inductance. The close proximity ensures the integrity and response speed of the gate drive signal, improving the reliability and consistency of the switching action of the MOSFET Q2.

[0049] In this embodiment, the main power supply branch 40 includes a third electronic switch Q3, a third voltage divider network V3, a fourth electronic switch Q4, and a fourth voltage divider network V4. The third electronic switch Q3 includes a first terminal, a second terminal, and a control terminal. The first terminal of the third electronic switch Q3 is electrically connected to the power supply unit 10, and the second terminal of the third electronic switch Q3 is electrically connected to the output interface 20. The third voltage divider network V3 includes a fifth resistor R5 and a sixth resistor R6. One end of the fifth resistor R5 is electrically connected to the first terminal of the third electronic switch Q3, and the other end of the fifth resistor R5 is electrically connected to the control terminal of the third electronic switch Q3 and one end of the sixth resistor R6. The fourth electronic switch Q4 includes a first terminal, a second terminal, and a control terminal. The first terminal of the fourth electronic switch Q4 is grounded, and the second terminal of the fourth electronic switch Q4 is electrically connected to the other end of the sixth resistor R6. The fourth voltage divider network V4 includes a seventh resistor R7 and an eighth resistor R8. One end of the seventh resistor R7 is electrically connected to the control terminal of the fourth electronic switch Q4 and one end of the eighth resistor R8. The other end of the seventh resistor R7 is grounded, and the other end of the eighth resistor R8 is connected to the second external control signal CONCTRL2_SIGNAL. In other embodiments, the first external control signal CONCTRL1_SIGNAL and the second external control signal CONCTRL2_SIGNAL can be accessed through independent ports, which is not limited here.

[0050] After the pre-charge branch 30 completes the pre-charging of the capacitive load and the second external control signal CONCTRL2_SIGNAL is enabled, the second external control signal CONCTRL2_SIGNAL controls the fourth electronic switch Q4 to turn on; when the fourth electronic switch Q4 is turned on, the sixth resistor R6 is grounded to enable the control terminal of the third electronic switch Q3, and the third electronic switch Q3 is turned on; when the third electronic switch Q3 is turned on, the main power supply branch 40 is turned on, bypassing the pre-charge branch 30, and the power supply unit 10 supplies power to the load unit through the main power supply branch 40.

[0051] When the second external control signal CONCTRL2_SIGNAL is not enabled, both the third electronic switch Q3 and the fourth electronic switch Q4 are in the off state, and the main power supply branch 40 is automatically in the isolated off state; when the second external control signal CONCTRL2_SIGNAL is enabled and then fails, the control terminal of the fourth electronic switch Q4 is pulled down to ground through the seventh resistor R7, the fourth electronic switch Q4 is opened, and then the third electronic switch Q3 is opened, forcibly disconnecting the power supply unit 10 from the load unit (making the main power supply branch in the disconnected state).

[0052] In this embodiment, the third electronic switch Q3 is a P-type MOS transistor and the fourth electronic switch Q4 is an N-type MOS transistor, but this is not a limitation. The first terminal of the third electronic switch Q3 and the fourth electronic switch Q4 is the source, the second terminal is the drain, and the control terminal is the gate.

[0053] In this embodiment, after the pre-charge branch 30 completes charging of the capacitive load, the voltage of the capacitive load is close to the battery voltage. When the second external control signal CONCTRL2_SIGNAL is enabled, MOSFET Q3 turns on, short-circuiting the high-energy resistor Rr. Thereafter, almost all the steady-state operating current flows through the MOSFET Q3 with its extremely low on-resistance, and no longer flows through the high-energy resistor Rr. This bypass mechanism eliminates the continuous power consumption of the high-energy resistor Rr during normal operation, avoids unnecessary energy dissipation in the form of Joule heat, significantly reduces system power consumption and internal temperature rise of the electrical control cabinet during continuous robot operation, and improves overall energy efficiency. MOSFET Q3, as the main power switch, carries all the operating current of the robot's joint motors and other loads in direct-on mode. By controlling the on-resistance of MOSFET Q3 to below 10mΩ, even with a continuous current of tens of amperes, the on-voltage drop and power consumption of MOSFET Q3 remain at extremely low levels (for example, with 20A, the on-power consumption is about 4W, but the actual average current is small, so the static power consumption is less than 0.5W). Low on-resistance not only reduces energy loss and heat generation, but also reduces voltage drop in the main circuit, ensuring that the downstream motor driver receives a stable power supply close to the battery voltage, and ensuring that the motor output torque and response speed are not affected by the internal resistance of the power supply.

[0054] The conduction of MOSFET Q3 is controlled by a second external control signal, CONCTRL2_SIGNAL, independent of the pre-charge branch 30. The external controller can flexibly determine the closing timing of the main switch MOSFET Q3. Setting the conduction condition to the output interface 20 voltage reaching 85%~95% of the battery voltage (i.e., the pre-charge completion criterion) ensures that at the instant MOSFET Q3 closes, the voltage difference between its drain and source has decreased to within 5%~15% of the battery voltage. When MOSFET Q3 is closed at this time, the inrush current flowing through MOSFET Q3 has been sufficiently attenuated by the current limiting process of the high-energy resistor Rr, avoiding the surge current several times the rated value generated when the main switch MOSFET Q3 is closed directly without pre-charge, thus protecting MOSFET Q3 itself and the subsequent circuit from current stress impact.

[0055] In practical applications, placing MOSFET Q3 close to the output interface 20 shortens the current path from the source of MOSFET Q3 to the load cell, reducing PCB trace resistance and parasitic inductance. The main current path utilizes a large-area copper layer with a thickness of at least 2 oz (approximately 70 μm), further reducing the resistance of the current-carrying loop. Under continuous high-current conditions, the low-resistance trace effectively reduces the heat generation and voltage drop of the PCB itself, lowering the temperature rise inside the control cabinet while ensuring the stability of the power supply voltage at the load end. When the robot's joint motors operate under continuous heavy loads, MOSFET Q3 needs to carry a large operating current for extended periods. By selecting a MOSFET with low on-resistance and using a large-area PCB heatsink, the heat generated by MOSFET Q3 can be effectively conducted to the PCB copper foil through the bottom of the package, and then dissipated into the surrounding air through natural convection and radiation. This design ensures that the junction temperature of MOSFET Q3 does not exceed the safe upper limit of 125°C, meeting thermal reliability requirements without the need for an additional heatsink or forced air cooling. This simplifies the system structure, reduces costs, and ensures the long-term stable operation of the MOSFET under all robot operating conditions.

[0056] In this embodiment, the working principle of the third voltage divider network V3 is similar to that of the first voltage divider network V1. The working principle of the fourth voltage divider network V4 is similar to that of the second voltage divider network V2, and will not be described again here.

[0057] In this embodiment, when the second external control signal CONCTRL2_SIGNAL is invalid, MOSFET Q4 is turned off, and the drain and source of MOSFET Q4 are in a high-impedance state, breaking the conduction path between the sixth resistor R6 and the ground terminal. The gate of MOSFET Q3 is pulled to a potential close to the source of MOSFET Q3 through the fifth resistor R5, causing MOSFET Q3 to turn off, thereby quickly isolating the main power supply branch 40. The gate threshold voltage of MOSFET Q4 is limited to the range of 1V to 2.5V, matching the drive voltage after the second external control signal CONCTRL2_SIGNAL (3.3V or 5V logic level) output by the external controller is divided by the seventh resistor R7 and the eighth resistor R8 in the fourth voltage divider network V4. This threshold range ensures reliable conduction under standard logic high level and reliable turn-off of MOSFET Q4 under logic low level or floating state. The direct level compatible design eliminates the need for a dedicated gate driver chip or level conversion circuit, reducing circuit complexity and material cost.

[0058] In this embodiment, the difference between the turn-on response time of MOSFET Q2 and the turn-on response time of MOSFET Q4 is less than a preset time. Specifically, limiting the difference between the turn-on response times of MOSFET Q2 and MOSFET Q4 to less than 10μs ensures that the control switch MOSFET Q2 of the pre-charge branch 30 and the control switch MOSFET Q4 of the main power supply branch 40 have similar hardware response speeds after receiving their respective enable signals. This timing matching helps reduce the risk of instantaneous logic conflicts caused by excessive differences in the action times of the two switches. For example, if the main power supply branch 40 turns on prematurely before the pre-charge branch 30 has completed pre-charging, causing a surge, or if the main power supply branch 40 has turned off but the pre-charge branch 30 is still conducting, causing the high-energy resistor Rr to remain energized.

[0059] The turn-on response time of the first external control signal CONCTRL1_SIGNAL is jointly determined by the third resistor R3, the fourth resistor R4, and the gate capacitance of MOSFET Q2. The turn-on response time of the second external control signal CONCTRL2_SIGNAL is jointly determined by the seventh resistor R7, the eighth resistor R8, and the gate capacitance of MOSFET Q4. By matching the third resistor R3, the fourth resistor R4, and the gate capacitance of MOSFET Q2; and by matching the seventh resistor R7, the eighth resistor R8, and the gate capacitance of MOSFET Q4, the response times of the two branches are made highly similar. The synchronicity of the response of the two control links ensures that the pre-charge branch 30 and the main power supply branch 40 can coordinate their actions when external signals change, avoiding instantaneous timing errors caused by excessively large differences in response time, and ensuring a smooth transition in the graded power-on process.

[0060] In this embodiment, the first external control signal CONCTRL1_SIGNAL is valid before the second external control signal CONCTRL2_SIGNAL. This ensures, from a system-level timing perspective, that the pre-charge branch 30 is turned on first to limit the current charging of the capacitive load, and the main power supply branch is turned on later to provide a low-impedance power supply path. During the initial power-on phase, the main switch MOSFET Q3 is in the off state, and the only path for the surge current is the pre-charge branch 30, where the high-energy resistor Rr is located. The high-energy resistor Rr preferentially carries and dissipates all the impact energy during capacitor charging. After pre-charging is completed, the main switch MOSFET Q3 turns on, bypassing the high-energy resistor Rr. Thereafter, almost all the steady-state operating current flows through the low on-resistance MOSFET Q3. This sequence avoids the huge surge current generated by directly closing the main switch when the capacitor is not charged, protecting the main switch MOSFET Q3, the power supply unit 10, and the subsequent driver from current stress impacts. The invalidation time of the first external control signal CONCTRL1_SIGNAL should be later than or equal to the invalidation time of the second external control signal CONCTRL2_SIGNAL to ensure that the main power supply branch 40 is turned off first, followed by the pre-charge branch 30 (or both are turned off simultaneously). This turn-off sequence avoids the abnormal state where the power supply unit 10 continuously discharges to the load unit through the high-energy resistor Rr when the main switch MOSFET Q3 is turned off but the MOSFET Q1 of the pre-charge branch is still conducting. This prevents the high-energy resistor Rr from overheating due to prolonged power supply, thus avoiding safety hazards, and also avoids incomplete power disconnection to the downstream load. When the robot is unexpectedly powered off and then powered on again, the external controller re-executes the complete sequence of the first external control signal CONCTRL1_SIGNAL first, followed by the second external control signal CONCTRL2_SIGNAL. This process ensures that even if the capacitive load is not fully discharged when power is restored, the pre-charge branch 30 will still intervene to limit the current, preventing the main switch MOSFET Q3 from directly closing on the residual voltage and generating an uncontrollable inrush current. This specification provides clear hardware behavior expectations for the abnormal recovery strategy of robot systems, ensuring equipment safety under repeated power-on conditions.

[0061] In this embodiment, the second external control signal CONCTRL2_SIGNAL of the main power supply branch 40 and the first external control signal CONCTRL1_SIGNAL of the precharge branch 30 are completely independent in hardware, with no hardware interlocking circuit consisting of resistors, capacitors, or logic gates between the two signals. The timing control of the two signals is completely delegated to an external controller (such as a robot main control unit) through software implementation, giving system integrators maximum flexibility: the precharge time and main switch closing timing can be dynamically adjusted according to different capacity loads, different battery voltages, or different operating conditions. At the same time, the absence of hardware interlocks simplifies the circuit structure, reduces the number of components and failure points, and improves the reliability of the circuit itself.

[0062] In this embodiment, the output interface 20 serves as a unified power output interface, integrating the precharge output and main power supply output onto the same terminal, and reserving unconnected terminals for functional expansion. Specifically, the output interface 20 has a first output terminal, a second output terminal, a third terminal, and a fourth terminal. The first output terminal is simultaneously connected to the drain of the first MOSFET Q1 in the precharge branch 30 and the drain of the MOSFET Q3 in the main power supply branch 40. The second output terminal is grounded, and the third and fourth terminals are in an unconnected state for functional expansion.

[0063] Compared to existing technologies, the pre-charging device and electronic device proposed in this application include a pre-charging branch containing a high-energy resistor and a main power supply branch. The pre-charging branch containing the high-energy resistor is first turned on according to a first external control signal, thereby connecting the power supply unit and the output interface. This allows the power supply unit to perform current-limited pre-charging of the capacitive load electrically connected to the output interface through the pre-charging branch. After the pre-charging branch completes the pre-charging of the capacitive load, the main power supply branch is turned on according to a second external control signal to connect the power supply unit and the output interface, allowing the power supply unit to supply power to the load unit through the main power supply branch. Therefore, in the initial stage of power-on, the main power supply branch is in a turned-off state, and the only path for surge current is the pre-charging branch containing the high-energy resistor. The high-energy resistor preferentially carries and dissipates all the impact energy during the capacitor charging process. After pre-charging is completed, the main power supply branch is turned on to bypass the high-energy resistor. Thereafter, almost all the steady-state operating current flows through the main power supply branch, avoiding the huge surge current generated by directly turning on the main power supply branch when the capacitor is not charged, and protecting the downstream driver and related devices from current stress impact. Once pre-charging is complete, the pre-charging time can be determined by either the output interface voltage reaching a preset ratio of the power supply output voltage, or by the pre-charging branch remaining continuously conducting for a preset duration.

[0064] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A pre-charge device applied to an electronic device including a capacitive load, characterized by, include: Power supply unit; An output interface is electrically connected to the load unit of the electronic device, the load unit including the capacitive load; The pre-charge branch contains a high-energy resistor and is electrically connected between the power supply unit and the output interface. It is used to connect the power supply unit and the output interface according to a first external control signal, so that the power supply unit performs current-limited pre-charging on the capacitive load through the pre-charge branch. The main power supply branch is electrically connected between the power supply unit and the output interface, and is connected in parallel with the pre-charge branch. When the pre-charge branch completes the pre-charging of the capacitive load, it connects the power supply unit and the output interface according to the second external control signal and bypasses the pre-charge branch, so that the power supply unit supplies power to the load unit through the main power supply branch. The first external control signal and the second external control signal are independent of each other, and the first external control signal and the second external control signal are enabled according to a preset timing rule.

2. The pre-charging device according to claim 1, characterized in that, The preset timing rule is as follows: When the electronic device is powered on, the first external control signal is enabled first, and the second external control signal is enabled after the pre-charge branch completes the pre-charging of the capacitive load. When the electronic device is powered off, the second external control signal fails first or the first external control signal and the second external control signal fail simultaneously.

3. The pre-charging device according to claim 1, characterized in that, The pre-charge branch includes: One end of the high-energy resistor is electrically connected to the power supply unit; A first electronic switch includes a first terminal, a second terminal, and a control terminal. The first terminal of the first electronic switch is electrically connected to the other end of the high-energy resistor, and the second terminal of the first electronic switch is electrically connected to the output interface. The first voltage divider network includes a first resistor and a second resistor. One end of the first resistor is electrically connected to the other end of the high-energy resistor, and the other end of the first resistor is electrically connected to the control terminal of the first electronic switch and one end of the second resistor. The second electronic switch includes a first terminal, a second terminal, and a control terminal. The first terminal of the second electronic switch is grounded, and the second terminal of the second electronic switch is electrically connected to the other end of the second resistor. The second voltage divider network includes a third resistor and a fourth resistor. One end of the third resistor is electrically connected to the control terminal of the second electronic switch and one end of the fourth resistor. The other end of the third resistor is grounded, and the other end of the fourth resistor is connected to the first external control signal.

4. The pre-charging device according to claim 3, characterized in that: When the first external control signal is enabled, the first external control signal controls the second electronic switch to turn on; When the second electronic switch is turned on, the second resistor is grounded, enabling the control terminal of the first electronic switch, and the first electronic switch is turned on. When the first electronic switch is turned on, the pre-charge branch is turned on, and the power supply unit performs current-limited charging of the capacitive load through the high-energy resistor.

5. The pre-charging device according to claim 3, characterized in that: When the first external control signal is not enabled, both the second electronic switch and the first electronic switch are in the off state, and the precharge branch is automatically in the isolated off state. When the first external control signal is enabled and then fails, the control terminal of the second electronic switch is pulled down to ground through the third resistor, the second electronic switch is turned off, and then the first electronic switch is turned off, forcibly disconnecting the power supply unit from the load unit.

6. The pre-charging device of claim 1, wherein, The main power supply branch includes: The third electronic switch includes a first terminal, a second terminal, and a control terminal. The first terminal of the third electronic switch is electrically connected to the power supply unit, and the second terminal of the third electronic switch is electrically connected to the output interface. The third voltage divider network includes a fifth resistor and a sixth resistor. One end of the fifth resistor is electrically connected to the first terminal of the third electronic switch, and the other end of the fifth resistor is electrically connected to the control terminal of the third electronic switch and one end of the sixth resistor. The fourth electronic switch includes a first terminal, a second terminal, and a control terminal. The first terminal of the fourth electronic switch is grounded, and the second terminal of the fourth electronic switch is electrically connected to the other end of the sixth resistor. The fourth voltage divider network includes a seventh resistor and an eighth resistor. One end of the seventh resistor is electrically connected to the control terminal of the fourth electronic switch and one end of the eighth resistor. The other end of the seventh resistor is grounded, and the other end of the eighth resistor is connected to the second external control signal.

7. The pre-charging device according to claim 6, characterized in that: The difference between the conduction response time of the second electronic switch and the conduction response time of the fourth electronic switch is less than a preset time.

8. The pre-charging device according to claim 6, characterized in that: When the pre-charge branch completes the pre-charge of the capacitive load and the second external control signal is enabled, the second external control signal controls the fourth electronic switch to turn on. When the fourth electronic switch is turned on, the sixth resistor is grounded to enable the control terminal of the third electronic switch, and the third electronic switch is turned on. When the third electronic switch is turned on, the main power supply branch is turned on, the pre-charge branch is bypassed, and the power supply unit supplies power to the load unit through the main power supply branch.

9. The pre-charging device according to claim 8, characterized in that: When the second external control signal is not enabled, both the third and fourth electronic switches are in the off state, and the main power supply branch is automatically in the isolated off state. When the second external control signal fails to enable, the control terminal of the fourth electronic switch is pulled down to ground through the seventh resistor, the fourth electronic switch is disconnected, and then the third electronic switch is disconnected, forcibly disconnecting the power supply unit from the load unit.

10. An electronic device, comprising: The pre-charging device as described in any one of claims 1 to 9; A controller is used to output a first external control signal and a second external control signal to the pre-charging device to control the pre-charging device.

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