Pre-charging circuit and method based on peak current and fixed turn-off time

Abstract

The invention discloses a pre-charging circuit and method based on peak current and fixed turn-off time, and belongs to the technical field of charging. The pre-charging sampling current is obtained by performing current sampling on the charging module, and the turn-off signal is generated when the pre-charging sampling current is consistent with the preset peak current, so that the charging module stops receiving the external power supply signal, and pre-charging of the load by the external power supply signal is turned off; the safety current value of the charging module cannot be exceeded under any input and output voltage condition, and the risks of inductance saturation and load damage are avoided; and after the receiving of the external power supply signal is stopped and the fixed turn-off time is preset, the pre-charging of the load can be restarted, so that the turn-on time of the pre-charging circuit can be adaptively shortened or prolonged according to the actual voltage difference, and the charging module can apply the maximum peak current to charge the load. Therefore, the average charging current is improved, the pre-charging time is shortened, and the pre-charging efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of charging technology, and particularly relates to a pre-charging circuit and method based on peak current and fixed off time. Background Technology

[0002] In electronic devices, especially systems that rely on large-capacity capacitors for energy storage and release, such as motor drives, inverters, and uninterruptible power supplies (UPS), a massive instantaneous current, or surge current, will be generated if full voltage is directly applied at the moment of power-on. This peak current may far exceed the normal operating current of the equipment by several times or even tens of times, putting enormous stress on electronic loads. This can lead to shortened component lifespan or even damage to the load. Pre-charge circuits, as a key safety measure to protect power electronic devices and power systems from surge current impacts, are currently commonly used for load pre-charging.

[0003] Most current pre-charging circuits are implemented using a buck converter. This involves a controller detecting the voltage difference between the power supply and the load to calculate the turn-on time of the MOSFET in the buck converter. The MOSFET is repeatedly switched on and off with a fixed turn-on time. During this pre-charging process, the constant turn-on time results in a low average current and an excessively long pre-charging time. This fails to fully utilize the energy storage characteristics of the inductor, indirectly increasing the size of the inductor in the buck converter and reducing pre-charging efficiency. Furthermore, the fixed turn-on time can lead to inductor saturation when the inductance decreases, potentially causing load damage. Summary of the Invention

[0004] The present invention aims to provide a pre-charging circuit and method based on peak current and fixed off-time to solve the above-mentioned technical problems. By using a peak current control module and a fixed off-time control module, pre-charging control based on peak current and fixed off-time is realized, thereby improving the efficiency and safety of pre-charging.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a pre-charging circuit based on peak current and fixed off-time, comprising: a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module; The fixed off-time control module is used to receive a pre-charge enable signal and drive the charging module to start receiving external power supply signals based on the pre-charge enable signal. The charging module is used to receive external power supply signals to precharge a preset load; The pre-charge current sampling module is used to sample the current of the external power supply signal input to the charging module during the pre-charging process of the load to obtain the pre-charge sampling current. When the pre-charge sampling current is consistent with the preset peak current, the peak current control module generates a shutdown signal so that the fixed shutdown time control module drives the charging module to stop receiving external power supply signals based on the shutdown signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the preset initial current, the peak current control module generates an enable signal, so that the fixed off-time control module, based on the enable signal, drives the charging module to resume receiving external power supply signals after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

[0006] Understandably, this invention constructs a pre-charging circuit using a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module. The pre-charging sampling current is obtained by sampling the current of the charging module. When the pre-charging sampling current matches the preset peak current, a off-time signal is generated, causing the charging module to stop receiving external power supply signals and cutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions, but also avoids the risk of inductor saturation and load damage due to reduced inductance. Furthermore, the introduction of a fixed off-time allows the pre-charging circuit to restart pre-charging of the load after each preset fixed off-time period after stopping receiving external power supply signals. This allows the on-time of the pre-charging circuit to adaptively shorten or extend according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving pre-charging efficiency.

[0007] As a preferred embodiment, the peak current control module includes: a third resistor, a seventh resistor, a voltage comparator, and a fourth resistor; The second end of the third resistor is electrically connected to the first end of the seventh resistor; The first end of the third resistor is electrically connected to the first end of the fourth resistor; The second terminal of the fourth resistor is electrically connected to the output terminal of the voltage comparator. The first terminal of the seventh resistor is electrically connected to the non-inverting input terminal of the voltage comparator; The second terminal of the seventh resistor is grounded; The second end of the third resistor is used to receive a preset peak current; The inverting input of the voltage comparator serves as the pre-charge current input of the peak current control module, and is electrically connected to the pre-charge current output of the pre-charge current sampling module. The output terminal of the voltage comparator serves as the control signal output terminal of the peak current control module, and is electrically connected to the control signal input terminal of the fixed off-time control module. When the pre-charge sampling current is consistent with the preset peak current, the voltage comparator generates a turn-off signal so that the fixed turn-off time control module drives the charging module to stop receiving external power supply signals based on the turn-off signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the voltage comparator generates an enable signal, so that the fixed off-time control module, based on the enable signal, drives the charging module to resume receiving external power supply signals after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

[0008] In the above scheme, a voltage comparator compares the pre-charge sampling current with the peak current, and also compares the pre-charge sampling current with the initial current. When the pre-charge sampling current matches the preset peak current, the voltage comparator generates a turn-off signal, causing the charging module to stop receiving external power supply signals and cut off the pre-charging of the load by the external power supply signal. This not only ensures that the safe current value of the charging module will not be exceeded under any input or output voltage conditions, but also avoids the risk of inductor saturation and load damage due to the reduction of inductance. When the pre-charge sampling current matches the initial current, an on signal is generated, allowing the charging module to restart the pre-charging of the load after a preset fixed turn-off time each time it stops receiving external power supply signals. This allows the on-time of the pre-charge circuit to be adaptively shortened or extended according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving the pre-charging efficiency.

[0009] As a preferred embodiment, the peak current control module further includes: a peak current buffer unit; the peak current buffer unit includes: a sixth resistor and a sixth capacitor; The first end of the sixth resistor is electrically connected to the first end of the seventh resistor; The second terminal of the sixth resistor is electrically connected to the non-inverting input terminal of the voltage comparator. The second end of the sixth resistor is electrically connected to the first end of the sixth capacitor; The second terminal of the sixth capacitor is grounded.

[0010] In the above scheme, the peak current buffer unit is formed by the sixth resistor and the sixth capacitor, which can prevent the peak current generated by the excessive voltage difference of the load and the delay of the circuit signal at the moment of power-on. In this way, the peak current can be controlled to rise smoothly from a low value to a preset stable value, effectively smoothing the peak current curve, eliminating the current overshoot at the moment of power-on, and improving the safety of pre-charging.

[0011] As a preferred embodiment, the fixed shutdown time control module includes: a fixed shutdown time control unit and a charging control unit; The first terminal of the fixed off-time control unit serves as the control signal input terminal of the fixed off-time control module, and is electrically connected to the output terminal of the voltage comparator. The second terminal of the fixed off-time control unit is grounded; The start / stop signal output terminal of the fixed off-time control unit is electrically connected to the start / stop signal input terminal of the charging control unit. The power supply control output terminal of the charging control unit is electrically connected to the power supply control input terminal of the charging module; When the pre-charge sampling current is consistent with the preset peak current, the fixed off-time control unit generates a charging off-time signal based on the off-time signal, so that the charging control unit drives the charging module to stop receiving external power supply signals based on the charging off-time signal, thereby adjusting the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the fixed off-time control unit generates a charging start signal based on the start signal, so that the charging control unit drives the charging module to start receiving external power supply signals again after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

[0012] In the above scheme, a fixed off-time control module is formed by a fixed off-time control unit and a charging control unit. When the pre-charging sampling current is consistent with the preset peak current, a charging off-time signal is generated, which causes the charging module to stop receiving external power supply signals and turn off the external power supply signals to pre-charge the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input and output voltage conditions, but also avoids the risk of inductor saturation and load damage caused by the reduction of inductance. Then, the fixed off-time is introduced so that the pre-charging circuit can restart the pre-charging of the load after each preset fixed off-time after stopping receiving external power supply signals. This allows the turn-on time of the pre-charging circuit to be adaptively shortened or extended according to the actual voltage difference, so that the charging module can apply the maximum peak current to charge the load, thereby improving the average charging current, shortening the pre-charging time, and improving the pre-charging efficiency.

[0013] As a preferred embodiment, the fixed off-time control unit includes: a second diode, an eighth resistor, and a fifth capacitor; The positive terminal of the second diode is electrically connected to the first terminal of the eighth resistor; The cathode of the second diode is electrically connected to the second terminal of the eighth resistor; The first terminal of the fifth capacitor is electrically connected to the second terminal of the eighth resistor; The second terminal of the fifth capacitor serves as the second terminal of the fixed off-time control unit, and the second terminal of the fifth capacitor is grounded. The first end of the eighth resistor serves as the control signal input terminal of the fixed off-time control module and is electrically connected to the output terminal of the voltage comparator. The first terminal of the fifth capacitor serves as the start / stop signal output terminal of the fixed off-time control unit, and is electrically connected to the start / stop signal input terminal of the charging control unit.

[0014] In the above scheme, an RC circuit is formed by the eighth resistor and the fifth capacitor, and its time constant determines the length of the fixed off-time. The second diode determines the discharge current flow of the fifth capacitor. When the voltage comparator outputs a turn-off signal, the second diode provides a very low-impedance discharge path for the fifth capacitor, causing the voltage of the fifth capacitor to be rapidly pulled down. This enables the fifth capacitor to generate a charging off-time signal, thereby causing the charging module to stop receiving external power supply signals and cut off the pre-charging of the load by the external power supply signal. This not only ensures that the safe current value of the charging module will not be exceeded under any input and output voltage conditions, but also avoids the risk of electrical overload. The reduced inductance leads to inductor saturation and load damage risks. When the pre-charge sampling current matches the initial current, the turn-on signal output by the voltage comparator charges the fifth capacitor through the eighth resistor. The voltage of the fifth capacitor continuously increases. After a fixed off time, the voltage of the fifth capacitor meets the requirements to generate a charging turn-on signal, allowing the pre-charging of the load to resume. This enables the turn-on time of the pre-charge circuit to be adaptively shortened or extended according to the actual voltage difference, allowing the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charge time, and improving pre-charge efficiency. By setting the parameters of the eighth resistor and the fifth capacitor, the length of the fixed off time can be controlled, further improving the flexibility and adaptability of the pre-charge circuit.

[0015] As a preferred embodiment, the charging control unit includes: an AND gate chip; The first terminal of the AND gate chip serves as the start / stop signal input terminal of the charging control unit, and it is electrically connected to the first terminal of the fifth capacitor. The output terminal of the AND gate chip serves as the power supply control output terminal of the charging control unit, and is electrically connected to the power supply control input terminal of the charging module. The second terminal of the AND gate chip is used to receive a pre-charge enable signal, so that the AND gate chip drives the charging module to start receiving external power supply signals based on the pre-charge enable signal.

[0016] In the above scheme, the charging control unit adopts an AND gate chip, which improves the accuracy and reliability of the charging module control through the logic control method of the AND gate chip itself. It can also take into account the charging start signal and the charging stop signal, ensuring the correct operation of the charging module and avoiding charging abnormalities in the pre-charging circuit.

[0017] As a preferred embodiment, the charging module includes: a first MOSFET, a first diode, and a first inductor; The drain of the first MOSFET is electrically connected to the anode of the first diode; The drain of the first MOSFET is electrically connected to the first terminal of the first inductor; The gate of the first MOS transistor is electrically connected as the power supply control input terminal of the charging module, and is also electrically connected to the output terminal of the AND gate chip. The source of the first MOSFET is connected to the negative terminal of an external power supply; the negative terminal of the first diode is connected to the positive terminal of an external power supply; both the source of the first MOSFET and the negative terminal of the first diode are used to receive external power supply signals. The negative terminal of the first diode is electrically connected to the first pre-charge port of the load; the second terminal of the first inductor is electrically connected to the second pre-charge port of the load.

[0018] In the above scheme, the charging module of the BUCK circuit is formed by the first MOSFET, the first diode and the first inductor. By controlling the conduction and cutoff of the first MOSFET, the charging module can receive external power supply signals. The first diode and the first inductor play a rectification and protection role, preventing the reverse current from damaging the circuit components. Thus, the pre-charging function can be effectively realized, ensuring the charging stability and accuracy of the pre-charging circuit.

[0019] As a preferred embodiment, the pre-charge current sampling module includes: a first resistor, a fifth resistor, a ninth resistor, a third capacitor, a fourth capacitor, a second resistor, a tenth resistor, a seventh capacitor, and a differential operational amplifier; The first end of the first resistor is electrically connected to the negative terminal of the power supply. The second terminal of the first resistor is electrically connected to the source of the first MOS transistor; The first end of the fifth resistor is electrically connected to the second end of the first resistor; The second end of the fifth resistor is electrically connected to the non-inverting input terminal of the differential operational amplifier; The first end of the ninth resistor is electrically connected to the first end of the first resistor; The second terminal of the ninth resistor is electrically connected to the inverting input terminal of the differential operational amplifier; The first terminal of the fourth capacitor is electrically connected to the second terminal of the fifth resistor; The second terminal of the fourth capacitor is electrically connected to the second terminal of the ninth resistor; The second terminal of the third capacitor is electrically connected to the second terminal of the fifth resistor; The second terminal of the second resistor is electrically connected to the second terminal of the fifth resistor; The first terminal of the second resistor is grounded; the first terminal of the third capacitor is grounded. The first end of the tenth resistor is electrically connected to the second end of the ninth resistor; The second end of the tenth resistor is electrically connected to the output end of the differential operational amplifier; The first terminal of the seventh capacitor is electrically connected to the first terminal of the tenth resistor; The second terminal of the seventh capacitor is electrically connected to the second terminal of the tenth resistor; The first resistor is used to sample the current of the external power supply signal input to the first inductor during the pre-charging process of the load to obtain the initial sampling current; The output terminal of the differential operational amplifier serves as the pre-charge current output terminal of the pre-charge current sampling module, and is electrically connected to the inverting input terminal of the voltage comparator. The differential operational amplifier is used to amplify the initial sampling current to obtain the pre-charge sampling current.

[0020] In the above scheme, the initial sampling current is obtained by sampling the current through the first inductor; the remaining resistors and capacitors form a filtering and signal processing circuit to filter and adjust the initial sampling current and improve the quality of the sampling signal; then the initial sampling current is amplified by a differential operational amplifier, making the pre-charge sampling current more accurate and reliable, thereby improving the accuracy and control precision of the pre-charge circuit.

[0021] As a preferred embodiment, the pre-charging circuit further includes: a load pre-charging protection module; The load precharge protection module includes: a first capacitor; The first terminal of the first capacitor is electrically connected to the negative terminal of the first diode; The second terminal of the first capacitor is electrically connected to the second terminal of the first inductor.

[0022] In the above scheme, the first capacitor forms a load pre-charge protection module, which makes the voltage applied across the load more stable; avoids damage to the load caused by voltage fluctuations, provides a relatively stable pre-charge environment for the load, and further protects the safe and stable operation of the load during the pre-charge process.

[0023] Accordingly, embodiments of the present invention provide a pre-charging method based on peak current and fixed off-time, applicable to a pre-charging circuit based on peak current control and fixed off-time as described above; the pre-charging method includes: The system acquires a power supply, a load, and a pre-charging circuit based on peak current control and a fixed off-time as described above, and electrically connects the power supply, the load, and the pre-charging circuit; wherein the pre-charging circuit includes: a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module; A pre-charge enable signal is input to the fixed off-time control module, so that the fixed off-time control module drives the charging module to start receiving external power supply signals based on the pre-charge enable signal, thereby enabling the charging module to pre-charge the load. During the pre-charging process of the load, the pre-charging current sampling module samples the external power supply signal input to the charging module to obtain the pre-charging sampling current. When the pre-charge sampling current is consistent with the preset peak current, the peak current control module generates a shutdown signal so that the fixed shutdown time control module drives the charging module to stop receiving external power supply signals based on the shutdown signal, thereby adjusting the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the peak current control module generates an enable signal, so that the fixed off-time control module, based on the enable signal, drives the charging module to resume receiving external power supply signals after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

[0024] Understandably, this invention constructs a pre-charging circuit using a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module. The pre-charging sampling current is obtained by sampling the current of the charging module. When the pre-charging sampling current matches the preset peak current, a off-time signal is generated, causing the charging module to stop receiving external power supply signals and cutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions, but also avoids the risk of inductor saturation and load damage due to reduced inductance. Furthermore, the introduction of a fixed off-time allows the pre-charging circuit to restart pre-charging of the load after each preset fixed off-time period after stopping receiving external power supply signals. This allows the on-time of the pre-charging circuit to adaptively shorten or extend according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving pre-charging efficiency. Attached Figure Description

[0025] Figure 1 A schematic diagram of a pre-charging circuit based on peak current and fixed off time is provided for an embodiment of the present invention; Figure 2 A schematic diagram showing the specific connection of a pre-charging circuit based on peak current and fixed off time, provided for an embodiment of the present invention; Figure 3 A voltage and current diagram of the pre-charging process provided in an embodiment of the present invention; Figure 4 The flowchart illustrates the steps of a pre-charging method based on peak current and fixed off-time, as provided in an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 Please refer to Figure 1 and 2 , Figure 1 This is a schematic diagram of a pre-charging circuit based on peak current and fixed off time, provided in an embodiment of the present invention. Figure 2 A schematic diagram showing the specific connection of a pre-charging circuit based on peak current and fixed off time, provided for an embodiment of the present invention; The pre-charge circuit includes: a charging module 1, a peak current control module 3, a fixed off-time control module 4, and a pre-charge current sampling module 2; The fixed off-time control module 4 is used to receive the pre-charge enable signal and drive the charging module 1 to start receiving the external power supply signal based on the pre-charge enable signal. The charging module 1 is used to receive external power supply signals to precharge the preset load C2; The pre-charge current sampling module 2 is used to sample the external power supply signal input to the charging module 1 during the pre-charging process of the load C2 to obtain the pre-charge sampling current. When the pre-charge sampling current is consistent with the preset peak current, the peak current control module 3 generates a shutdown signal so that the fixed shutdown time control module 4 drives the charging module 1 to stop receiving external power supply signals based on the shutdown signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the preset initial current, the peak current control module 3 generates an enable signal, so that the fixed off-time control module 4, based on the enable signal, drives the charging module 1 to start receiving external power supply signals again after the charging module 1 stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load C2 is completed.

[0028] In an alternative embodiment, such as Figure 2 As shown, grounding in this embodiment is represented using SGND.

[0029] In this embodiment, as Figure 2 As shown, the peak current control module 3 includes: a third resistor R3, a seventh resistor R7, a voltage comparator IC2, and a fourth resistor R4; The second end of the third resistor R3 is electrically connected to the first end of the seventh resistor R7; The first end of the third resistor R3 is electrically connected to the first end of the fourth resistor R4; The second terminal of the fourth resistor R4 is electrically connected to the output terminal of the voltage comparator IC2. The first terminal of the seventh resistor R7 is electrically connected to the non-inverting input terminal of the voltage comparator IC2; The second terminal of the seventh resistor R7 is grounded; The second end of the third resistor R3 is used to receive a preset peak current; The inverting input terminal of the voltage comparator IC2 serves as the pre-charge current input terminal of the peak current control module 3, and is electrically connected to the pre-charge current output terminal of the pre-charge current sampling module 2. The output terminal of the voltage comparator IC2 serves as the control signal output terminal of the peak current control module 3, and is electrically connected to the control signal input terminal of the fixed off-time control module 4. When the pre-charge sampling current is consistent with the preset peak current, the voltage comparator IC2 generates a turn-off signal so that the fixed turn-off time control module 4 drives the charging module 1 to stop receiving external power supply signals based on the turn-off signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the voltage comparator IC2 generates an enable signal, so that the fixed off-time control module 4, based on the enable signal, drives the charging module 1 to resume receiving the external power supply signal after the charging module 1 stops receiving the external power supply signal for a preset fixed off-time, until the pre-charging of the load C2 is completed.

[0030] This embodiment compares the pre-charge sampling current with the peak current and the initial current using a voltage comparator. When the pre-charge sampling current matches the preset peak current, the voltage comparator generates a shutdown signal, causing the charging module to stop receiving external power supply signals and shutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions, but also avoids the risk of inductor saturation and load damage due to reduced inductance. When the pre-charge sampling current matches the initial current, an on signal is generated, allowing the charging module to restart pre-charging the load after a preset fixed shutdown time each time it stops receiving external power supply signals. This allows the on-time of the pre-charge circuit to be adaptively shortened or extended according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving pre-charging efficiency.

[0031] In this embodiment, as Figure 2 As shown, the peak current control module 3 further includes: a peak current buffer unit; the peak current buffer unit includes: a sixth resistor R6 and a sixth capacitor C6; The first end of the sixth resistor R6 is electrically connected to the first end of the seventh resistor R7; The second terminal of the sixth resistor R6 is electrically connected to the non-inverting input terminal of the voltage comparator IC2; The second end of the sixth resistor R6 is electrically connected to the first end of the sixth capacitor C6; The second terminal of the sixth capacitor C6 is grounded.

[0032] This embodiment uses a sixth resistor and a sixth capacitor to form a peak current buffer unit, which can prevent the peak current generated by the excessive voltage difference of the load and the delay of the circuit signal at the moment of power-on. This allows the peak current to be controlled to rise smoothly from a lower value to a preset stable value, effectively smoothing the peak current curve, eliminating the current overshoot at the moment of power-on, and improving the safety of pre-charging.

[0033] In this embodiment, as Figure 1 As shown, the fixed shutdown time control module 4 includes: a fixed shutdown time control unit 41 and a charging control unit 42; The first terminal of the fixed off-time control unit 41 serves as the control signal input terminal of the fixed off-time control module 4, and is electrically connected to the output terminal of the voltage comparator IC2. The second terminal of the fixed off-time control unit 41 is grounded; The start / stop signal output terminal of the fixed off-time control unit 41 is electrically connected to the start / stop signal input terminal of the charging control unit 42. The power supply control output terminal of the charging control unit 42 is electrically connected to the power supply control input terminal of the charging module 1; When the pre-charge sampling current is consistent with the preset peak current, the fixed off-time control unit 41 generates a charging off-time signal based on the off-time signal, so that the charging control unit 42 drives the charging module 1 to stop receiving external power supply signals based on the charging off-time signal, thereby adjusting the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the fixed off-time control unit 41 generates a charging start signal based on the start signal, so that the charging control unit 42 drives the charging module 1 to start receiving external power supply signals again after the charging module 1 stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load C2 is completed.

[0034] This embodiment uses a fixed off-time control module composed of a fixed off-time control unit and a charging control unit. When the pre-charge sampling current matches the preset peak current, a charging off-time signal is generated, causing the charging module to stop receiving external power supply signals and shutting off the pre-charging of the load by the external power supply signal. This not only ensures that the safe current value of the charging module will not be exceeded under any input or output voltage conditions, but also avoids the risk of inductor saturation and load damage caused by the reduction of inductance. Subsequently, the introduction of a fixed off-time allows the pre-charging circuit to restart the pre-charging of the load after each preset fixed off-time after stopping the reception of external power supply signals. This allows the on-time of the pre-charging circuit to be adaptively shortened or extended according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving the pre-charging efficiency.

[0035] In this embodiment, as Figure 2 As shown, the fixed off-time control unit 41 includes: a second diode D2, an eighth resistor R8, and a fifth capacitor C5; The positive terminal of the second diode D2 is electrically connected to the first terminal of the eighth resistor R8; The cathode of the second diode D2 is electrically connected to the second terminal of the eighth resistor R8; The first terminal of the fifth capacitor C5 is electrically connected to the second terminal of the eighth resistor R8. The second terminal of the fifth capacitor C5 serves as the second terminal of the fixed off-time control unit 41, and the second terminal of the fifth capacitor C5 is grounded. The first end of the eighth resistor R8 serves as the control signal input terminal of the fixed off-time control module 4, and is electrically connected to the output terminal of the voltage comparator IC2. The first terminal of the fifth capacitor C5 serves as the start / stop signal output terminal of the fixed off-time control unit 41, and is electrically connected to the start / stop signal input terminal of the charging control unit 42.

[0036] In this embodiment, an RC circuit is constructed using an eighth resistor and a fifth capacitor, the time constant of which determines the length of the fixed off-time. The second diode determines the discharge current flow direction of the fifth capacitor. When the voltage comparator outputs a turn-off signal, the second diode provides a very low-impedance discharge path for the fifth capacitor, rapidly pulling down its voltage. This allows the fifth capacitor to generate a charging off-time signal, causing the charging module to stop receiving external power supply signals and cutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions but also avoids the inductance-induced current surges. The reduced current introduces risks of inductor saturation and load damage. When the pre-charge sampling current matches the initial current, the turn-on signal output by the voltage comparator charges the fifth capacitor through the eighth resistor. The voltage of the fifth capacitor continuously increases. After a fixed off time, the voltage of the fifth capacitor meets the requirements to generate a charging turn-on signal, allowing the pre-charging of the load to resume. This enables the turn-on time of the pre-charge circuit to be adaptively shortened or extended according to the actual voltage difference, allowing the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charge time, and improving pre-charge efficiency. By setting the parameters of the eighth resistor and the fifth capacitor, the length of the fixed off time can be controlled, further improving the flexibility and adaptability of the pre-charge circuit.

[0037] In this embodiment, as Figure 2 As shown, the charging control unit 42 includes: an AND gate chip IC1; The first terminal A of the AND gate chip IC1 serves as the start / stop signal input terminal of the charging control unit 42, and is electrically connected to the first terminal of the fifth capacitor C5. The output terminal Y of the AND gate chip IC1 serves as the power supply control output terminal of the charging control unit 42, and is electrically connected to the power supply control input terminal of the charging module 1. The second terminal B of the AND gate chip IC1 is used to receive a pre-charge enable signal, so that the AND gate chip IC1 drives the charging module 1 to start receiving external power supply signals based on the pre-charge enable signal.

[0038] This embodiment uses an AND gate chip in the charging control unit. The AND gate chip's own logic control method improves the accuracy and reliability of the charging module control. It can also take into account both the charging start signal and the charging stop signal, ensuring the correct operation of the charging module and avoiding charging abnormalities in the pre-charging circuit.

[0039] As a preferred option, such as Figure 2 As shown, the charging module 1 includes: a first MOSFET Q1, a first diode D1, and a first inductor L1; The drain of the first MOSFET Q1 is electrically connected to the positive terminal of the first diode D1; The drain of the first MOSFET Q1 is electrically connected to the first terminal of the first inductor L1; The gate of the first MOS transistor Q1 is electrically connected as the power supply control input terminal of the charging module 1, and is electrically connected to the output terminal Y of the AND gate chip IC1. The source of the first MOSFET Q1 is connected to the negative terminal of the external power supply VI-; the negative terminal of the first diode D1 is connected to the positive terminal of the external power supply VI+; the source of the first MOSFET Q1 and the negative terminal of the first diode D1 are both used to receive external power supply signals. The negative terminal of the first diode D1 is electrically connected to the first pre-charge port VO+ of the load C2; the second terminal of the first inductor L1 is electrically connected to the second pre-charge port VO- of the load C2.

[0040] In this embodiment, a charging module for a BUCK circuit is constructed using a first MOSFET, a first diode, and a first inductor. By controlling the conduction and cutoff of the first MOSFET, the charging module's reception of external power supply signals is controlled. The first diode and the first inductor serve to rectify and protect the circuit components, preventing reverse current flow and damage. This effectively enables the pre-charging function and ensures the charging stability and accuracy of the pre-charging circuit.

[0041] In this embodiment, as Figure 2 As shown, the pre-charge current sampling module 2 includes: a first resistor R1, a fifth resistor R5, a ninth resistor R9, a third capacitor C3, a fourth capacitor C4, a second resistor R2, a tenth resistor R10, a seventh capacitor C7, and a differential operational amplifier IC3. The first terminal of the first resistor R1 is electrically connected to the negative terminal VI- of the power supply. The second end of the first resistor R1 is electrically connected to the source of the first MOSFET Q1; The first end of the fifth resistor R5 is electrically connected to the second end of the first resistor R1. The second end of the fifth resistor R5 is electrically connected to the non-inverting input terminal of the differential operational amplifier IC3; The first end of the ninth resistor R9 is electrically connected to the first end of the first resistor R1. The second terminal of the ninth resistor R9 is electrically connected to the inverting input terminal of the differential operational amplifier IC3; The first terminal of the fourth capacitor C4 is electrically connected to the second terminal of the fifth resistor R5; The second terminal of the fourth capacitor C4 is electrically connected to the second terminal of the ninth resistor R9; The second terminal of the third capacitor C3 is electrically connected to the second terminal of the fifth resistor R5; The second terminal of the second resistor R2 is electrically connected to the second terminal of the fifth resistor R5; The first terminal of the second resistor R2 is grounded; the first terminal of the third capacitor C3 is grounded. The first end of the tenth resistor R10 is electrically connected to the second end of the ninth resistor R9; The second terminal of the tenth resistor R10 is electrically connected to the output terminal of the differential operational amplifier IC3; The first terminal of the seventh capacitor C7 is electrically connected to the first terminal of the tenth resistor R10; The second terminal of the seventh capacitor C7 is electrically connected to the second terminal of the tenth resistor R10; The first resistor R1 is used to sample the current of the external power supply signal input to the first inductor L1 during the pre-charging process of the load C2 to obtain the initial sampling current. The output terminal of the differential operational amplifier IC3 serves as the pre-charge current output terminal of the pre-charge current sampling module 2, and is electrically connected to the inverting input terminal of the voltage comparator IC2. The differential operational amplifier IC3 is used to amplify the initial sampling current to obtain the pre-charge sampling current.

[0042] In this embodiment, the initial sampling current is obtained by sampling the current through the first inductor; the remaining resistors and capacitors form a filtering and signal processing circuit to filter and adjust the initial sampling current, thereby improving the quality of the sampling signal; then, the initial sampling current is amplified by a differential operational amplifier, making the pre-charge sampling current more accurate and reliable, thereby improving the accuracy and control precision of the pre-charge circuit.

[0043] In an optional embodiment, the pre-charging circuit is powered by 5V. Figure 2 The simplified representation is "5V". The power supply input of the differential operational amplifier IC3 is electrically connected to the power supply of the pre-charge circuit, and the ground terminal of the differential operational amplifier IC3 is grounded. The power supply input of the voltage comparator IC2 is electrically connected to the power supply of the pre-charge circuit, and the ground terminal of the voltage comparator IC2 is grounded. The power supply input of the AND gate chip is electrically connected to the power supply of the pre-charge circuit, and the ground terminal of the AND gate chip is grounded.

[0044] In this embodiment, as Figure 2 As shown, the pre-charge circuit further includes: a load pre-charge protection module; the load pre-charge protection module includes: a first capacitor C1; The first terminal of the first capacitor C1 is electrically connected to the negative terminal of the first diode D1; The second terminal of the first capacitor C1 is electrically connected to the second terminal of the first inductor L1.

[0045] This embodiment uses a first capacitor to form a load pre-charge protection module, which makes the voltage applied across the load more stable; avoids damage to the load caused by voltage fluctuations, provides a relatively stable pre-charge environment for the load, and further protects the safe and stable operation of the load during the pre-charge process.

[0046] In an alternative embodiment, such as Figure 2 As shown, the working principle of the pre-charge circuit provided in this embodiment is described in detail. In order to prevent the peak current generated by the excessive voltage difference of the load at the moment of power-on and the delay of the circuit signal, so as to control the peak current to rise smoothly from a lower value to a preset stable value, the sixth resistor and the sixth capacitor constitute a peak current buffer unit, so that the voltage at the non-inverting input terminal of the voltage comparator IC2 rises slowly, thereby controlling the peak current of pre-charge to rise slowly. When the second terminal B of the AND gate chip IC1 receives the pre-charge enable signal, pre-charge begins. The AND gate chip IC1 drives the first MOS transistor Q1 to conduct, and the power supply (VI+ and VI-) charges the load C2 through the first inductor L1. The current of the first inductor L1 rises linearly. After being sampled by the first resistor R1, the initial sampling current is obtained. Then, it is amplified by the differential operational amplifier IC3 to obtain the pre-charge sampling current, and the pre-charge sampling current is input to the inverting input terminal of the voltage comparator IC2. The voltage at the non-inverting input terminal of the voltage comparator IC2 receives the preset peak current. The peak current is set below the saturation current of the first inductor L1. When the pre-charge sampling current reaches the peak current, the voltage comparator IC2 outputs a low level (i.e., a turn-off signal). At this time, after receiving the low level, the fifth capacitor C5 quickly discharges to the reference voltage value of D2 through the second diode D2, which is set to 0.5V in this embodiment. The high level value of the AND gate chip IC1 is set to 2.4V in this embodiment. At this time, the voltage of the fifth capacitor C5 is lower than the high level value of the AND gate chip IC1. Therefore, the fifth capacitor C5 will generate a 0.5V voltage signal (i.e., a charging turn-off signal) to the AND gate chip IC1. The AND gate chip IC1 then outputs a low level, turning off the first MOSFET Q1, thereby stopping the reception of external power supply signals. After stopping the reception of external power supply signals, the first inductor L1 will continue to charge the load C2 through the first diode D1. At this time, the current on the first inductor L1 is not 0, but since the reception of external power supply signals has stopped, the external power supply signals of the power supply will not flow to the first inductor L1. Because the first MOSFET Q1 is turned off, the current through the first resistor R1 becomes 0, meaning the initial sampling current and the pre-charge sampling current are both 0. In this embodiment, the initial current is set to 0. At this time, the pre-charge sampling current is the same as the initial current, and the voltage at the inverting input of voltage comparator IC2 is 0. At this time, voltage comparator IC2 outputs a high level (i.e., an enable signal, set to 5V in this embodiment), charging the fifth capacitor C5 through the eighth resistor R8. The voltage on the fifth capacitor C5 continues to rise. After a fixed turn-off time (i.e., the time it takes for the fifth capacitor C5 to rise from 0.5V to 2.4V; the fixed turn-off time specifically refers to the time it takes for the voltage on the fifth capacitor C5 to rise through the eighth resistor R8), the voltage across the fifth capacitor C5 continues to rise. (Determined by resistor R8), the voltage on the fifth capacitor C5 rises to 2.4V, thus generating a 2.4V voltage signal (i.e., the charging start signal). Since the 2.4V voltage signal is higher than the high level value of the AND gate chip IC1, the AND gate chip IC1 outputs a high level, turning on the first MOSFET Q1. At this time, the power supply (VI+ and VI-) charges the load C2 through the first inductor L1. The current of the first inductor L1 rises linearly, and this process repeats until the voltage of the load C2 is close to the voltage of the power supply (VI+ and VI-), completing the pre-charging of the load C2. At this time, the pre-charging sampling current is 0, and the first MOSFET Q1 remains normally open.

[0047] In one alternative embodiment, please refer to Figure 3 , Figure 3 This is a voltage and current diagram of the pre-charging process provided in an embodiment of the present invention; as shown below. Figure 3 As shown, where, Figure 3 The horizontal axis represents the on / off state of the first MOSFET Q1, where T1, T2, and T3 indicate that the first MOSFET Q1 is on, and Toff indicates that the first MOSFET Q1 is off. The "current" in the first diagram represents the current through the first inductor L1. The "voltage" in the middle diagram represents the power supply voltage (VIN) and the voltage across the load C2 (VO). Figure 3 It can be deduced that after the pre-charge enable signal is received, in time T1, when the first MOSFET Q1 is turned on, the current in the first inductor L1 rises from 0 to the peak current, and the voltage of the load C2 rises synchronously. When the current in the first inductor L1 rises to the peak current, the pre-charge sampling current is also the peak current. Therefore, the first MOSFET Q1 is turned off, and the current in the first inductor L1 begins to decrease. However, since the first inductor L1 will freewheel through the first diode D1, it continues to charge the load C2. At this time, the current in the first inductor L1 is not 0, and the voltage of the load C2 is still rising synchronously. This cycle repeats until the voltage of the load C2 is close to the voltage of the power supply, completing the pre-charge of the load C2.

[0048] This embodiment constructs a pre-charging circuit using a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module. The pre-charging sampling current is obtained by sampling the current of the charging module. When the pre-charging sampling current matches the preset peak current, a off-time signal is generated, causing the charging module to stop receiving external power supply signals and cutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions, but also avoids the risk of inductor saturation and load damage due to reduced inductance. A fixed off-time is then introduced, allowing the pre-charging circuit to restart pre-charging of the load after each preset fixed off-time period after stopping receiving external power supply signals. This allows the on-time of the pre-charging circuit to adaptively shorten or extend according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving pre-charging efficiency.

[0049] Please refer to Figure 4 , Figure 4 A flowchart of a pre-charging method based on peak current and fixed off time provided for an embodiment of the present invention includes steps S501 to S505. Step S501: Obtain a power supply, a load, and a pre-charging circuit based on peak current control and a fixed off-time, and electrically connect the power supply, the load, and the pre-charging circuit; wherein, the pre-charging circuit includes: a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module.

[0050] Step S502: Input a pre-charge enable signal to the fixed off-time control module, so that the fixed off-time control module drives the charging module to start receiving external power supply signals based on the pre-charge enable signal, thereby enabling the charging module to pre-charge the load.

[0051] Step S503: During the pre-charging process of the load, the external power supply signal input to the charging module is sampled based on the pre-charging current sampling module to obtain the pre-charging sampling current.

[0052] Step S504: When the pre-charge sampling current is consistent with the preset peak current, a turn-off signal is generated based on the peak current control module, so that the fixed turn-off time control module drives the charging module to stop receiving external power supply signals based on the turn-off signal, so as to adjust the pre-charge sampling current to the preset initial current.

[0053] Step S505: When the pre-charge sampling current is consistent with the initial current, the peak current control module generates an enable signal so that the fixed off-time control module, based on the enable signal, drives the charging module to restart receiving the external power supply signal after the charging module stops receiving the external power supply signal for a preset fixed off-time, until the pre-charging of the load is completed.

[0054] This embodiment constructs a pre-charging circuit using a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module. The pre-charging sampling current is obtained by sampling the current of the charging module. When the pre-charging sampling current matches the preset peak current, a off-time signal is generated, causing the charging module to stop receiving external power supply signals and cutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions, but also avoids the risk of inductor saturation and load damage due to reduced inductance. A fixed off-time is then introduced, allowing the pre-charging circuit to restart pre-charging of the load after each preset fixed off-time period after stopping receiving external power supply signals. This allows the on-time of the pre-charging circuit to adaptively shorten or extend according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving pre-charging efficiency.

[0055] In summary, this embodiment of the invention constructs a pre-charging circuit using a charging module, a peak current control module, a fixed off-time control module, and a pre-charging current sampling module. The pre-charging sampling current is obtained by sampling the current of the charging module. When the pre-charging sampling current matches the preset peak current, a off-time signal is generated, causing the charging module to stop receiving external power supply signals and cutting off the pre-charging of the load. This not only ensures that the safe current value of the charging module will not be exceeded under any input / output voltage conditions, but also avoids the risk of inductor saturation and load damage due to reduced inductance. Furthermore, the introduction of a fixed off-time allows the pre-charging circuit to restart pre-charging of the load after each preset fixed off-time period after stopping receiving external power supply signals. This allows the on-time of the pre-charging circuit to adaptively shorten or extend according to the actual voltage difference, enabling the charging module to apply the maximum peak current to charge the load, thereby increasing the average charging current, shortening the pre-charging time, and improving pre-charging efficiency.

[0056] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A pre-charge circuit based on peak current and fixed off-time, characterized in that, include: Charging module, peak current control module, fixed off-time control module and pre-charge current sampling module; The fixed off-time control module is used to receive a pre-charge enable signal and drive the charging module to start receiving external power supply signals based on the pre-charge enable signal. The charging module is used to receive external power supply signals to precharge a preset load; The pre-charge current sampling module is used to sample the current of the external power supply signal input to the charging module during the pre-charging process of the load to obtain the pre-charge sampling current. When the pre-charge sampling current is consistent with the preset peak current, the peak current control module generates a shutdown signal so that the fixed shutdown time control module drives the charging module to stop receiving external power supply signals based on the shutdown signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the preset initial current, the peak current control module generates an enable signal, so that the fixed off-time control module, based on the enable signal, drives the charging module to resume receiving external power supply signals after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

2. The pre-charging circuit based on peak current and fixed off-time as described in claim 1, characterized in that, The peak current control module includes: a third resistor, a seventh resistor, a voltage comparator, and a fourth resistor; The second end of the third resistor is electrically connected to the first end of the seventh resistor; The first end of the third resistor is electrically connected to the first end of the fourth resistor; The second terminal of the fourth resistor is electrically connected to the output terminal of the voltage comparator. The first terminal of the seventh resistor is electrically connected to the non-inverting input terminal of the voltage comparator; The second terminal of the seventh resistor is grounded; The second end of the third resistor is used to receive a preset peak current; The inverting input of the voltage comparator serves as the pre-charge current input of the peak current control module, and is electrically connected to the pre-charge current output of the pre-charge current sampling module. The output terminal of the voltage comparator serves as the control signal output terminal of the peak current control module, and is electrically connected to the control signal input terminal of the fixed off-time control module. When the pre-charge sampling current is consistent with the preset peak current, the voltage comparator generates a turn-off signal so that the fixed turn-off time control module drives the charging module to stop receiving external power supply signals based on the turn-off signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the voltage comparator generates an enable signal, so that the fixed off-time control module, based on the enable signal, drives the charging module to resume receiving external power supply signals after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

3. The pre-charging circuit based on peak current and fixed off-time as described in claim 2, characterized in that, The peak current control module further includes: a peak current buffer unit; the peak current buffer unit includes: a sixth resistor and a sixth capacitor; The first end of the sixth resistor is electrically connected to the first end of the seventh resistor; The second terminal of the sixth resistor is electrically connected to the non-inverting input terminal of the voltage comparator. The second end of the sixth resistor is electrically connected to the first end of the sixth capacitor; The second terminal of the sixth capacitor is grounded.

4. A pre-charging circuit based on peak current and fixed off-time as described in claim 2, characterized in that, The fixed shutdown time control module includes: a fixed shutdown time control unit and a charging control unit; The first terminal of the fixed off-time control unit serves as the control signal input terminal of the fixed off-time control module, and is electrically connected to the output terminal of the voltage comparator. The second terminal of the fixed off-time control unit is grounded; The start / stop signal output terminal of the fixed off-time control unit is electrically connected to the start / stop signal input terminal of the charging control unit. The power supply control output terminal of the charging control unit is electrically connected to the power supply control input terminal of the charging module; When the pre-charge sampling current is consistent with the preset peak current, the fixed off-time control unit generates a charging off-time signal based on the off-time signal, so that the charging control unit drives the charging module to stop receiving external power supply signals based on the charging off-time signal, thereby adjusting the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the fixed off-time control unit generates a charging start signal based on the start signal, so that the charging control unit drives the charging module to start receiving external power supply signals again after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

5. A pre-charging circuit based on peak current and fixed off-time as described in claim 4, characterized in that, The fixed off-time control unit includes: a second diode, an eighth resistor, and a fifth capacitor; The positive terminal of the second diode is electrically connected to the first terminal of the eighth resistor; The cathode of the second diode is electrically connected to the second terminal of the eighth resistor; The first terminal of the fifth capacitor is electrically connected to the second terminal of the eighth resistor; The second terminal of the fifth capacitor serves as the second terminal of the fixed off-time control unit, and the second terminal of the fifth capacitor is grounded. The first end of the eighth resistor serves as the control signal input terminal of the fixed off-time control module and is electrically connected to the output terminal of the voltage comparator. The first terminal of the fifth capacitor serves as the start / stop signal output terminal of the fixed off-time control unit, and is electrically connected to the start / stop signal input terminal of the charging control unit.

6. A pre-charging circuit based on peak current and fixed off-time as described in claim 5, characterized in that, The charging control unit includes: an AND gate chip; The first terminal of the AND gate chip serves as the start / stop signal input terminal of the charging control unit, and it is electrically connected to the first terminal of the fifth capacitor. The output terminal of the AND gate chip serves as the power supply control output terminal of the charging control unit, and is electrically connected to the power supply control input terminal of the charging module. The second terminal of the AND gate chip is used to receive a pre-charge enable signal, so that the AND gate chip drives the charging module to start receiving external power supply signals based on the pre-charge enable signal.

7. A pre-charging circuit based on peak current and fixed off-time as described in claim 6, characterized in that, The charging module includes: a first MOSFET, a first diode, and a first inductor; The drain of the first MOSFET is electrically connected to the anode of the first diode; The drain of the first MOSFET is electrically connected to the first terminal of the first inductor; The gate of the first MOS transistor is electrically connected as the power supply control input terminal of the charging module, and is also electrically connected to the output terminal of the AND gate chip. The source of the first MOSFET is connected to the negative terminal of an external power supply; the negative terminal of the first diode is connected to the positive terminal of an external power supply; both the source of the first MOSFET and the negative terminal of the first diode are used to receive external power supply signals. The negative terminal of the first diode is electrically connected to the first pre-charge port of the load; the second terminal of the first inductor is electrically connected to the second pre-charge port of the load.

8. A pre-charging circuit based on peak current and fixed off-time as described in claim 7, characterized in that, The pre-charge current sampling module includes: a first resistor, a fifth resistor, a ninth resistor, a third capacitor, a fourth capacitor, a second resistor, a tenth resistor, a seventh capacitor, and a differential operational amplifier; The first end of the first resistor is electrically connected to the negative terminal of the power supply. The second terminal of the first resistor is electrically connected to the source of the first MOS transistor; The first end of the fifth resistor is electrically connected to the second end of the first resistor; The second end of the fifth resistor is electrically connected to the non-inverting input terminal of the differential operational amplifier; The first end of the ninth resistor is electrically connected to the first end of the first resistor; The second terminal of the ninth resistor is electrically connected to the inverting input terminal of the differential operational amplifier; The first terminal of the fourth capacitor is electrically connected to the second terminal of the fifth resistor; The second terminal of the fourth capacitor is electrically connected to the second terminal of the ninth resistor; The second terminal of the third capacitor is electrically connected to the second terminal of the fifth resistor; The second terminal of the second resistor is electrically connected to the second terminal of the fifth resistor; The first terminal of the second resistor is grounded; the first terminal of the third capacitor is grounded. The first end of the tenth resistor is electrically connected to the second end of the ninth resistor; The second end of the tenth resistor is electrically connected to the output end of the differential operational amplifier; The first terminal of the seventh capacitor is electrically connected to the first terminal of the tenth resistor; The second terminal of the seventh capacitor is electrically connected to the second terminal of the tenth resistor; The first resistor is used to sample the current of the external power supply signal input to the first inductor during the pre-charging process of the load to obtain the initial sampling current; The output terminal of the differential operational amplifier serves as the pre-charge current output terminal of the pre-charge current sampling module, and is electrically connected to the inverting input terminal of the voltage comparator. The differential operational amplifier is used to amplify the initial sampling current to obtain the pre-charge sampling current.

9. A pre-charging circuit based on peak current and fixed off-time as described in claim 7, characterized in that, It also includes: a load precharge protection module; The load precharge protection module includes: a first capacitor; The first terminal of the first capacitor is electrically connected to the negative terminal of the first diode; The second terminal of the first capacitor is electrically connected to the second terminal of the first inductor.

10. A pre-charging method based on peak current and fixed off-time, applicable to a pre-charging circuit based on peak current control and fixed off-time as described in any one of claims 1 to 9; characterized in that, The pre-charging method includes: The system acquires a power supply, a load, and a pre-charging circuit based on peak current control and fixed off time as described in any one of claims 1 to 9, and electrically connects the power supply, the load, and the pre-charging circuit; wherein the pre-charging circuit includes: a charging module, a peak current control module, a fixed off time control module, and a pre-charging current sampling module; A pre-charge enable signal is input to the fixed off-time control module, so that the fixed off-time control module drives the charging module to start receiving external power supply signals based on the pre-charge enable signal, thereby enabling the charging module to pre-charge the load. During the pre-charging process of the load, the pre-charging current sampling module samples the external power supply signal input to the charging module to obtain the pre-charging sampling current. When the pre-charge sampling current is consistent with the preset peak current, a shutdown signal is generated based on the peak current control module, so that the fixed shutdown time control module drives the charging module to stop receiving external power supply signals based on the shutdown signal, so as to adjust the pre-charge sampling current to the preset initial current. When the pre-charge sampling current is consistent with the initial current, the peak current control module generates an enable signal, so that the fixed off-time control module, based on the enable signal, drives the charging module to resume receiving external power supply signals after the charging module stops receiving external power supply signals for a preset fixed off-time, until the pre-charging of the load is completed.

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