Soft start circuit, control method thereof and power supply device

Abstract

The application provides a slow start circuit, a control method thereof and a power supply device. The slow start circuit comprises a controller, a switching unit, a freewheeling unit, an energy storage unit and an energy release unit. The switching unit is coupled between a first end of a power module and the energy release unit. The energy release unit is coupled to a second end of the energy storage unit. A first end of the freewheeling unit is coupled to a second end of the power module and a first end of the energy storage unit. A second end of the freewheeling unit is coupled to a node between the switching unit and the energy release unit. In a first time period, the controller is configured to control the switching unit to be turned on, so that the power module charges the energy storage unit through the energy release unit. In a second time period, the controller is configured to control the switching unit to be turned off, so that the energy release unit discharges the energy storage unit through the freewheeling unit. The first time period and the second time period are one working cycle. The embodiment of the application can slow start, reduce the size and cost.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and in particular to a soft-start circuit, its control method, and a power supply device. Background Technology

[0002] Soft-start circuits can be applied to input ports that require hot-swapping or have capacitive loads. Because the capacitor short-circuits at the moment of power-on, the current in the input circuit can instantly increase to infinity, which may cause input device protection and switch arcing. In more serious cases, it may damage the components in the input circuit. Therefore, it is necessary to add a soft-start circuit to the input circuit.

[0003] Existing soft-start circuits use a capacitor connected in parallel with a Metal-Oxide-Semiconductor (MOS) transistor to achieve soft-start through the Miller plateau of the MOS transistor, thus achieving a current-limiting soft-start effect. However, this MOS transistor will operate in the linear region for a long time, requiring the selection of a device with a larger Safe Operating Area (SOA). Furthermore, MOS transistors with larger SOA also have larger package sizes, which undoubtedly increases the layout area and cost, thereby affecting the overall size of the soft-start circuit. Summary of the Invention

[0004] In view of this, this application provides a soft-start circuit, its control method, and a power supply device, which can achieve the function of soft start, and reduce the size and cost.

[0005] In a first aspect, embodiments of this application provide a soft-start circuit for start-up control during the power supply process of a power module to a load device. The soft-start circuit includes a controller, a switching unit, a freewheeling unit, an energy storage unit, an energy release unit, and a controller. The controller is coupled to the switching unit; the switching unit is coupled between a first terminal of the power module and the energy release unit, and the energy release unit is coupled to a second terminal of the energy storage unit; the first terminal of the freewheeling unit is coupled between the second terminal of the power module and the first terminal of the energy storage unit, and the second terminal of the freewheeling unit is coupled to a node between the switching unit and the energy release unit. In a first time period, the controller controls the switching unit to turn on, so that the power module charges the energy storage unit via the energy release unit. In a second time period, the controller controls the switching unit to turn off, so that the energy release unit discharges to the energy storage unit via the freewheeling unit. The first time period and the second time period constitute one operating cycle.

[0006] The soft-start circuit of the embodiment of this application reduces the requirements of the soft-start circuit for the switching unit. The switching unit can be selected with a smaller SOA, and the package size of the switch with a larger SOA is also smaller, thereby reducing the size of the switch, reducing the size of the circuit board, and thus reducing the volume of the entire soft-start circuit and the volume of the power supply equipment.

[0007] In one possible design, the controller is coupled to the energy storage unit to detect the voltage of the energy storage unit. Based on this design, the controller acquires the state of the energy storage unit in real time and can control the state of the switching unit according to the state of the energy storage unit, thereby achieving a slow start-up process of the power supply equipment supplying power to the load equipment and improving the safety performance of the power supply equipment.

[0008] In one possible design, when the difference between the voltage of the energy storage unit and the input voltage of the power module is less than a voltage threshold, the controller controls the switching unit to turn on, thereby controlling the power module to supply power to the load device. Based on this design, when the voltage of the energy storage unit approaches the input voltage of the power module, the controller can terminate the soft start of the power supply device and keep the switching unit in the on state. In this way, the power module can supply power to the load device.

[0009] In one possible design, the switching unit is any one of a field-effect transistor, a transistor, a triode, or a relay.

[0010] In one possible design, the energy storage unit is a capacitor and the energy release unit is an inductor.

[0011] In one possible design, the freewheeling unit includes a diode, the cathode of which is coupled to a second terminal of the power module and a first terminal of the energy storage unit, and the anode of which is coupled to a node between the switching unit and the energy release unit.

[0012] Secondly, embodiments of this application provide a soft-start circuit for start-up control during the power supply process of a power module to a load device. The soft-start circuit includes a controller, a switching unit, a freewheeling unit, an energy storage unit, an energy release unit, and another controller. The controller is coupled to the switching unit; the switching unit is coupled between a first terminal of the power module and a first terminal of the energy storage unit; the first terminal of the energy release unit is coupled between a second terminal of the power module and a first terminal of the freewheeling unit; the second terminal of the energy release unit is coupled to a second terminal of the energy storage unit; and the second terminal of the freewheeling unit is coupled to a node between the switching unit and the first terminal of the energy storage unit. In a first time period, the controller controls the switching unit to turn on, so that the power module charges the energy storage unit via the energy release unit. In a second time period, the controller controls the switching unit to turn off, so that the energy release unit discharges to the energy storage unit via the freewheeling unit. The first time period and the second time period constitute one operating cycle.

[0013] The soft-start circuit of the embodiment of this application reduces the requirements of the soft-start circuit for the switching unit. The switching unit can be selected with a smaller SOA, and the package size of the switch with a larger SOA is also smaller, thereby reducing the size of the switch, reducing the size of the circuit board, and thus reducing the volume of the entire soft-start circuit and the volume of the power supply equipment.

[0014] Thirdly, embodiments of this application also provide a control method for a soft-start circuit, the soft-start circuit including a controller, a switching unit, a freewheeling unit, an energy storage unit, and an energy release unit; the control method for the soft-start circuit includes: controlling the switching unit to conduct during a first time period to control the power module to charge the energy storage unit; and controlling the switching unit to turn off during a second time period to control the energy release unit to discharge to the energy storage unit via the freewheeling unit. The first time period and the second time period constitute one operating cycle.

[0015] The control method employed in this application embodiment enables a slow start-up process from the power supply device to the load device, thereby improving the safety performance of the power supply device. Furthermore, the control method for the slow-start circuit in this application embodiment has the advantages of simple logic control and low cost.

[0016] In one possible design, the control method of the soft-start circuit further includes: detecting the voltage of the energy storage unit; if the voltage of the energy storage unit is equal to the input voltage of the power supply device, or if the voltage difference between the voltage of the energy storage unit and the input voltage of the power supply device is less than a preset threshold, controlling the switching unit to always operate in the on state.

[0017] Based on this design, the controller can keep the switching unit in the ON state, which will end the soft start of the power supply equipment by the soft start circuit, that is, the soft start process ends.

[0018] Thirdly, embodiments of this application also provide a power supply device, which includes a power module and the soft-start circuit described above.

[0019] The soft-start circuit, control method, and power supply device provided in this application embodiment can realize the slow start-up process of the power supply device to the load device, thereby improving the safety performance of the power supply device. In this application embodiment, the switching transistor can be a device with a smaller SOA, and the package size of MOS transistors with larger SOA is also smaller, thereby reducing the size of the switching transistor, the size of the circuit board, and thus the overall volume of the soft-start circuit, and also reducing the volume of the power supply device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the power supply equipment provided according to an embodiment of this application.

[0021] Figure 2 This is a circuit diagram of a soft-start circuit provided according to an embodiment of this application.

[0022] Figure 3 This is a voltage-time relationship diagram of an energy storage unit according to an embodiment of this application during charging.

[0023] Figure 4 This is a diagram showing the relationship between the state and time of a switching unit according to an embodiment of this application.

[0024] Figure 5 This is another circuit diagram of the soft-start circuit provided according to an embodiment of this application.

[0025] Figure 6 This is another circuit diagram of the soft-start circuit provided according to an embodiment of this application.

[0026] Figure 7 This is another circuit diagram of the soft-start circuit provided according to an embodiment of this application.

[0027] Figure 8 This is a diagram showing the relationship between the state and time of a switching unit according to an embodiment of this application.

[0028] Figure 9 This is a flowchart of a control method for a soft-start circuit provided according to an embodiment of this application.

[0029] Explanation of main component symbols

[0030] Power supply equipment 100 load device 200 Soft start circuit 10 Switching unit 11 Freewheeling unit 12 Energy storage unit 13 controller 14 Energy release unit 15 Current detection unit 16 Power module 20 Power conversion module 30 switch Q1 capacitance C1-C2 inductance L1 diode D1

[0031] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0032] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component that is centrally located.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] In communication systems, some load devices contain capacitors, such as power supplies, routers, and switches. When these load devices are powered on, the capacitors are prone to short-circuiting. Once a short circuit occurs, the current in the power supply circuit can surge instantaneously, potentially causing overload restarts of upstream circuits or even damage to components in the power supply circuit. Therefore, adding a soft-start circuit to the power supply circuit is crucial.

[0035] In one scenario, a soft-start circuit can employ a Metal Oxide Semiconductor (MOS) transistor connected in parallel with a capacitor, using the Miller plateau of the MOS transistor to achieve soft start, thereby realizing current limiting and soft start. However, in this approach, the MOS transistor operates in the linear region, placing very high demands on the MOS transistor itself. Specifically, a device with a large Safe Operating Area (SOA) is required, and MOS transistors with larger SOA also have larger package sizes. This undoubtedly increases the layout area and cost, thus affecting the overall size of the soft-start circuit.

[0036] To address the problems in the above scenarios, embodiments of this application provide a soft-start circuit and a power supply device. The soft-start circuit can be used for startup control during the power supply process from the power module to the load device, achieving a soft-start effect while reducing its size and cost.

[0037] Please see Figure 1 , Figure 1The diagram shown is a structural schematic of a power supply device 100 according to an embodiment of this application. The power supply device 100 in this embodiment can be coupled to the load device 200. In one possible scenario, the power supply device 100 can be used to supply power to the load device 200.

[0038] Specifically, the power supply device 100 may include a soft-start circuit 10 and a power module 20. The soft-start circuit 10 may be coupled between the power module 20 and the load device 200. It is understood that the soft-start circuit 10 can play a soft-start role during the process of the power module 20 supplying power to the load device 200, and the soft-start circuit 10 can reduce its size and the size of the circuit board, thereby reducing the overall size of the soft-start circuit and lowering costs.

[0039] It is understood that, in one possible implementation, the power supply device 100 may further include a power conversion module 30. The power conversion module 30 may be coupled between the soft-start circuit 10 and the load device 200. In one embodiment, the power conversion module 30 may be a voltage converter that transforms the input voltage and effectively outputs a fixed voltage. For example, the power conversion module 30 may be a DC-DC converter. For instance, the power supply device 100 may use the power conversion module 30 to convert the input power (e.g., -48V) into the required power, such as 5V, 3.3V, 2.5V, etc., thereby providing power to the load device 200. It is understood that, to reduce the current surge when the load device is plugged in, embodiments of this application may connect the soft-start circuit 10 before the power conversion module 30.

[0040] It is understandable that, due to the high voltage difference between the input and output voltages of the power supply device 100, and the presence of large capacitors in the circuit for filtering and preventing instantaneous power loss, which undergo charging and discharging, the insertion and power-on of the power module 20 may cause an impact on the -48V power supply. The instantaneous large current will cause the voltage of the -48V power supply to drop, potentially affecting the normal operation of other components. Simultaneously, due to the instantaneous large current, significant arcing will occur at the connectors when the board is inserted, causing electromagnetic interference and corrosion of the connectors. Therefore, to solve the above technical problems, it is necessary to control the power-on rate of the -48V power supply, i.e., to add the soft-start circuit 10. When hot-plugging occurs, the soft-start circuit 10 can slowly power on the power supply, thereby reducing the current surge to the power conversion module 30.

[0041] Please see Figure 2 , Figure 2The diagram shown is a schematic diagram of the circuit structure of a soft-start circuit 10 provided in one embodiment of this application.

[0042] The soft-start circuit 10 in this embodiment may include a switching unit 11, a freewheeling unit 12, an energy storage unit 13, a controller 14, an energy release unit 15, and a current detection unit 16.

[0043] It is understood that the power module 20 in this embodiment may include an output terminal VCC1 and an output terminal VCC2. It is also understood that the voltage at the output terminal VCC1 may be higher than the voltage at the output terminal VCC2. The embodiments of this application do not specifically limit the voltage level of the power supply, nor do they limit the positive or negative voltage; for example, it can be a positive voltage or a negative voltage. For example, in one implementation, when the power module 20 is a negative voltage power supply, the output terminal VCC1 can be 0V, and the output terminal VCC2 can be -48V.

[0044] The switching unit 11 can be coupled between the output terminal VCC2 and the first terminal of the energy release unit 15. The second terminal of the energy release unit 15 can be coupled to the second terminal of the energy storage unit 13 and the power conversion module 30. The first terminal of the freewheeling unit 12 can be coupled to the output terminal VCC1 and the first terminal of the energy storage unit 13. The second terminal of the freewheeling unit 12 can be coupled to the node between the switching unit 11 and the energy release unit 15.

[0045] The controller 14 can be coupled to the switching unit 11 to control the switching unit 11 to turn on and off. For example, when the switching unit 11 is on, the power module 20 can charge the energy storage unit 13. When the switching unit 11 is off, the energy release unit 15 can discharge the energy storage unit 13 via the freewheeling unit 12.

[0046] For example, in one embodiment, the switching unit 11 may include a switch Q1, and the freewheeling unit 12 may include a diode D1. The energy storage unit 13 may include a capacitor C1, and the energy release unit 15 may include an inductor L1. It is understood that in one possible implementation, the switch Q1 may be a semiconductor power device; for example, the switch Q1 may be any one of a field-effect transistor, a transistor, and a bipolar junction transistor (BJT). The field-effect transistor is a metal-oxide-semiconductor field-effect transistor (MOSFET), abbreviated as MOS transistor, and the type of MOS transistor may include PMOS and NMOS.

[0047] The first terminal of switch Q1 can be coupled to the first terminal of inductor L1, the second terminal of switch Q1 can be coupled to the output terminal VCC2 of power module 20, and the third terminal of switch Q1 can also be coupled to the first pin 1 of controller 14. The third terminal of switch Q1 can serve as the control terminal for switch Q1. The first pin 1 of controller 14 can output a signal to switch Q1 to control its state.

[0048] The anode of diode D1 can be coupled to the node between the second terminal of switch Q1 and the first terminal of inductor L1, and the cathode of diode D1 can be coupled to the output terminal VCC1 of power module 20. The second terminal of inductor L1 can be coupled to the first terminal of capacitor C1 and power conversion module 30. The second terminal of capacitor C1 can be coupled to the output terminal VCC1 of power module 20 and power conversion module 30. In one possible implementation, the second pin 2 of controller 14 can be coupled to current detection unit 16, which can also be coupled between the second terminal of switch Q1 and the anode of diode D1. The third pin 3 of controller 14 can be coupled to the node between the first terminal of capacitor C1 and power conversion module 30. Based on this design, controller 14 can detect the voltage of capacitor C1 in real time and control the state of switch Q1 according to the voltage of capacitor C1. The first output terminal of the power conversion module 30 is coupled to the first terminal of the capacitor C2, and the second output terminal of the power conversion module 30 is coupled to the second terminal of the capacitor C2.

[0049] In the embodiments of this application, the capacitor C1 can be used for energy storage. The switch Q1 can be used to delay the charging of the capacitor C1, thereby preventing a large current from charging the capacitor C1 and thus achieving overcurrent protection.

[0050] The controller 14 can be used to control the state of the switch Q1. For example, the controller 14 can control the switch Q1 to be turned on or off.

[0051] like Figure 3 The diagram shows the charging process of capacitor C1. It can be seen that when the power supply device 100 is powered on, the soft-start circuit 10 periodically controls the switch Q1 to be in the on or off state, thereby charging capacitor C1, and the voltage of capacitor C1 gradually increases. When the voltage of capacitor C1 is equal to the input voltage of the power supply device 100, or when the voltage difference between the voltage of capacitor C1 and the input voltage of the power supply device 100 is less than a voltage threshold, the controller 14 can control the switch Q1 to remain in the on state.

[0052] Furthermore, the controller 14 can control the switch Q1 to be in the on state during a first time period, and then control the switch Q1 to be in the off state during a second time period. It can be understood that the first and second time periods can constitute a working cycle T. That is, the controller 14 can control the switch Q1 to operate in switching mode for multiple working cycles T.

[0053] Taking a work cycle T of 2 seconds as an example, for instance... Figure 4 As shown, the switching on for soft-start control can be divided into the following process: During the time period t1 (e.g., t1 can be a time period of 0.4s), the controller 14 can control the switch Q1 to turn on. During the time period t1, the current output by the power module 20 can flow through the output terminal VCC1, through the capacitor C1, the inductor L1, and the switch Q1. At this time, the current can charge the capacitor C1, and the current in the inductor L1 is also increasing, that is, the inductor L1 is in the process of storing energy.

[0054] During the time period t2 (e.g., t2 can be a time period of 1.6s), the controller 14 can also control the switch Q1 to turn off. During the time period t2, the power module 20 disconnects from the soft-start circuit 10, and the energy stored in the inductor L1 can form a freewheeling path through the diode D1, while charging the capacitor C1.

[0055] Next, during the time period t3 (for example, t3 can be a time period of 1.5s), the controller 14 controls the switch Q1 to be turned on. At this time, the current output by the power module 20 can flow through the output terminal VCC1, through the capacitor C1, the inductor L1, and the switch Q1, and the current can charge the capacitor C1.

[0056] During the time period t4 (for example, t4 can be a time period of 1.5s), the controller 14 can control the switch Q1 to turn off. At this time, the energy stored in the inductor L1 can form a freewheeling path through the diode D1 to charge the capacitor C1.

[0057] The controller 14 can control the switch Q1 to be turned on or off within multiple operating cycles T. During the on and off processes of the switch Q1, the power module 20 can charge the capacitor C1. When the voltage of the capacitor C1 is equal to the input voltage of the power supply device 100, or when the voltage difference between the voltage of the capacitor C1 and the input voltage of the power supply device 100 is less than a threshold, the controller 14 can control the switch Q1 to always operate in the on state.

[0058] In one possible implementation, the controller 14 can set the soft-start time of the soft-start circuit 10 based on the capacitance of the capacitor C1. For example, the controller 14 can control the number of times the switch Q1 is turned on and off, as well as the on-time and off-time within each working cycle T. For instance, the controller 14 can control the switch Q1 as follows: The switch Q1 operates for four working cycles T, each cycle lasting 3 seconds. In the first working cycle T1, the switch Q1 can be in the on state for 0.5 seconds and in the off state for 2.5 seconds. In the second working cycle T2, the switch Q1 can be in the on state for 0.6 seconds and in the off state for 2.4 seconds. In the third working cycle T3, the switch Q1 can be in the on state for 0.7 seconds and in the off state for 2.3 seconds. In the fourth working cycle T4, the switch Q1 can be in the on state for 0.8 seconds and in the off state for 2.2 seconds. Next, after the fourth operating cycle T4, the voltage of capacitor C1 reaches the same level as the input voltage of power module 20, thus ending the slow start process of the power supply device via the slow start circuit 10. The controller 14 will then keep switch Q1 in the ON state, indicating the end of the slow start process. Based on this design, the embodiments of this application can achieve a slow start process for the power supply device to supply power to the load device, improving the safety performance of the power supply device. Furthermore, the slow start circuit in the embodiments of this application allows for setting the slow start time, offering advantages such as simple logic control, simple circuit structure, and low cost.

[0059] Compared to the prior art where the MOSFET operates in the linear region for a long time, in the embodiments of this application, the switch Q1 can operate in pulse width modulation (PWM) mode, which reduces the requirements of the soft start circuit on the MOSFET. In other words, the MOSFET in the embodiments of this application can be a device with a smaller SOA, and the package size of the MOSFET with a larger SOA is also smaller, thereby reducing the size of the MOSFET, reducing the size of the circuit board, and thus reducing the volume of the entire soft start circuit and the volume of the power supply equipment.

[0060] Based on the design of the embodiments of this application, the soft-start circuit 10 can not only play the role of soft start, but also reduce the size it occupies and reduce the cost.

[0061] Please see Figure 5 , Figure 5 The diagram shown is a schematic diagram of the circuit structure of a soft-start circuit 10 provided in another embodiment of this application.

[0062] and Figure 2The difference between the illustrated embodiments is that, in this embodiment, as Figure 5 As shown, the first terminal of switch Q1 can be coupled to the first terminal of power module 20, the second terminal of switch Q1 can be coupled to the first terminal of capacitor C1 and power conversion module 30, and the third terminal of switch Q1 can be coupled to the first pin 1 of controller 14, wherein the third terminal of switch Q1 is the control terminal of switch Q1. The cathode of diode D1 can be coupled to the second terminal of switch Q1, the anode of diode D1 can be coupled to the first terminal of inductor L1, and the second terminal of inductor L1 can be coupled to the second terminal of capacitor C1 and power conversion module 30. The second pin 2 of controller 14 can be coupled to current detection unit 16, the current detection unit 16 can be coupled between the anode of diode D1 and output terminal VCC2, and the third pin 3 of controller 14 can be coupled to the first terminal of capacitor C1 to detect the voltage of capacitor C1.

[0063] Understandable. Figure 5 The switch Q1 in the illustrated embodiment can also operate in pulse width modulation (PWM) mode, which can reduce the requirements of the soft-start circuit on the MOSFET, reduce the size of the MOSFET, reduce the size of the circuit board, thereby reducing the overall size of the soft-start circuit and the size of the power supply equipment.

[0064] Please see Figure 6 , Figure 6 The diagram shown is a schematic diagram of the circuit structure of a soft-start circuit 10 provided in another embodiment of this application.

[0065] and Figure 2 The difference between the illustrated embodiments is that, in this embodiment, as Figure 6As shown, the first end of the inductor L1 can be coupled to the output terminal VCC1 of the power module 20, the second end of the inductor L1 can be coupled to the first end of the capacitor C1 and the power conversion module 30, the cathode of the diode D1 can be coupled to the first end of the inductor L1, the anode of the diode D1 can be coupled to the second end of the switch Q1, the first end of the switch Q1 can be coupled to the output terminal VCC2 of the power module 20, and the third end of the switch Q1 can be coupled to the first pin 1 of the controller 14, wherein the third end of the switch Q1 can be the control terminal of the switch Q1, and the second end of the capacitor C1 can be coupled to the power conversion module 30. The second pin 2 of the controller 14 can be coupled to the current detection unit 16, and the current detection unit 16 can also be coupled between the anode of the diode D1 and the second end of the switch Q1. The third pin 3 of the controller 14 can be coupled to the first end of the capacitor C1.

[0066] Understandable. Figure 6 The switch Q1 in the illustrated embodiment can also operate in pulse width modulation (PWM) mode, which can reduce the requirements of the soft-start circuit on the MOSFET, reduce the size of the MOSFET, reduce the size of the circuit board, thereby reducing the overall size of the soft-start circuit and the size of the power supply equipment.

[0067] Please see Figure 7 , Figure 7 The diagram shown is a schematic diagram of the circuit structure of a soft-start circuit 10 provided in another embodiment of this application.

[0068] and Figure 2 The difference between the illustrated embodiments is that, in this embodiment, as Figure 7 As shown, the first terminal of switch Q1 can be coupled to the output terminal VCC1 of the power module 20, the second terminal of switch Q1 can be coupled to the first terminal of inductor L1, the third terminal of switch Q1 can be coupled to the first pin 1 of controller 14, the second terminal of inductor L1 can be coupled to the power conversion module 30, the first terminal of inductor L1 can also be coupled to the first terminal of capacitor C1, the cathode of diode D1 can be coupled to the node between the second terminal of switch Q1 and the first terminal of inductor L1, and the anode of diode D1 can be coupled to the output terminal VCC2 of power module 20 and the second terminal of capacitor C1. The second pin 2 of controller 14 can be coupled to the current detection unit 16, the current detection unit 16 can be coupled between the anode of diode D1 and the output terminal VCC2, and the third pin 3 of controller 14 can be coupled to the first terminal of capacitor C1 to detect the voltage of capacitor C1.

[0069] In one possible implementation, the controller 14 can control the state of the switch Q1 based on the detected voltage of the capacitor C1. When the voltage difference between the input voltage of the power module 20 and the voltage of the capacitor C1 is less than a voltage threshold, the soft start of the power supply device can be terminated. For example, taking a voltage threshold of 1V as an example, if the input voltage of the power module 20 is 48V and the voltage of the capacitor C1 is 46V, then the voltage difference between the input voltage and the voltage of the capacitor C1 is 2V, which is greater than the voltage threshold. At this time, the power supply device 100 has not yet completed the circuit soft start, and the controller 14 controls the switch Q1 to PWM control mode. If the input voltage of the power module 20 is 48V and the voltage of capacitor C1 is 47.5V, then the voltage difference between the input voltage and the voltage of capacitor C1 is 0.5V, which is less than the voltage threshold. In this case, the power supply device 100 can complete the circuit's soft start, and the controller 14 controls the switch Q1 to remain continuously on. Based on this design, the soft start circuit in this embodiment can terminate the soft start when it detects that the voltage difference between the input voltage and the voltage of capacitor C1 has reached the voltage threshold, demonstrating strong adaptability.

[0070] In another possible implementation, the controller 14 can control the switch Q1 at different time periods. For example, Figure 8 As shown, during time period t1, the controller 14 controls the switch Q1 to operate in PWM mode, thereby charging the capacitor C1 until its voltage reaches a certain value. During time period t2, the controller 14 can detect the current of the power supply device through the current detection unit 16 and control the state of the switch Q1 based on the detected current. For example, if the detected current reaches 1A, the switch Q1 is turned off. At this time, the capacitor C1 is still charging until the voltage difference between the input voltage and the voltage of the capacitor C1 is less than the voltage threshold, at which point the soft start ends, and the switch Q1 is kept in a continuously conducting state.

[0071] Based on the above embodiments, the embodiments of this application can realize the slow start-up process of the power supply device to the load device, thereby improving the safety performance of the power supply device. In the embodiments of this application, the MOSFET can be a device with a smaller SOA, and the package size of the MOSFET with a larger SOA is also smaller, thereby reducing the size of the MOSFET, the size of the circuit board, and thus the volume of the entire soft-start circuit, and also reducing the size of the power supply device.

[0072] Please see Figure 9 The figure is a flowchart of a control method for a soft-start circuit according to an embodiment of this application. The control method for the soft-start circuit may include the following steps:

[0073] Step S91: The control switch unit is turned on during the first time period, thereby controlling the power module to charge the energy storage unit.

[0074] by Figure 2 Taking the soft-start circuit 10 as an example, the controller 14 can control the switching unit 11 to be in the conducting state during a first time period. For example, during the time period t1 (e.g., t1 can be a time period of 0.4s), the controller 14 can control the switch Q1 to be turned on. During the time period t1, the current output by the power module 20 can flow through the output terminal VCC1 through the energy storage unit 13, the energy release unit 15, and the switching unit 11. At this time, the current can charge the energy storage unit 13, and the current of the energy release unit 15 is also increasing, that is, the inductor L1 is in the process of energy storage.

[0075] Step S92: The control switch unit is turned off during the second time period, thereby controlling the energy release unit to discharge to the energy storage unit via the freewheeling unit. The first time period and the second time period constitute one operating cycle.

[0076] The controller 14 can control the switching unit 11 to be in an off state during a second time period. For example, during the time period t2 (e.g., t2 can be a time period of 1.6s), the controller 14 can also control the switching unit 11 to be turned off. During the time period t2, the power module 20 disconnects from the soft-start circuit 10, and the energy stored in the energy release unit 15 can form a freewheeling path through the freewheeling unit 12, while simultaneously charging the energy storage unit 13.

[0077] It can be understood that the first time period and the second time period can be a working cycle T. That is, the controller 14 can control the switching unit to operate in on and off modes within multiple working cycles T. Taking a working cycle T of 2s as an example, the first time period can be a time period of 0.4s and the second time period can be a time period of 1.6s. Alternatively, the first time period can be a time period of 0.3s and the second time period can be a time period of 1.7s.

[0078] Step S93: Detect the voltage of the energy storage unit.

[0079] by Figure 2Taking the soft-start circuit 10 shown as an example, the third pin 3 of the controller 14 can be coupled to the node between the first end of the energy storage unit 13 and the power conversion module 30. Therefore, the controller 14 can detect the voltage of the energy storage unit 13 in real time and control the state of the switching unit 11 according to the voltage of the energy storage unit 13.

[0080] Step S94: If the voltage of the energy storage unit is equal to the input voltage of the power supply device, or if the voltage difference between the voltage of the energy storage unit and the input voltage of the power supply device is less than a preset threshold, then control the switching unit to always work in the on state.

[0081] It is understood that in this embodiment, the controller 14 can control the switching unit 11 to be turned on or off within multiple operating cycles T. During the on and off processes of the switching unit 11, the power module 20 can charge the energy storage unit 13. When the voltage of the energy storage unit 13 is equal to the input voltage of the power supply device 100, or when the voltage difference between the voltage of the energy storage unit 13 and the input voltage of the power supply device 100 is less than a threshold, the controller 14 can control the switching unit 11 to always be in the on state, thus ending the slow start of the power supply device by the slow start circuit 10. The controller 14 will then control the switch Q1 to always be in the on state, i.e., the slow start process ends. Based on this design, the embodiments of this application can realize the slow start process of the power supply device supplying power to the load device, improving the safety performance of the power supply device. In addition, the control method of the slow start circuit in the embodiments of this application has the advantages of simple logic control and low cost.

[0082] Compared to the prior art where MOSFETs operate in the linear region for extended periods, the switching unit in this application can operate in pulse width modulation mode. This reduces the requirements of the soft-start circuit on the MOSFET. In other words, the MOSFETs in this application can be devices with smaller SOA, and MOSFETs with larger SOA also have smaller package sizes, thereby reducing the size of the MOSFET, the size of the circuit board, and thus the volume of the entire soft-start circuit and the power supply equipment.

[0083] Based on the design of the embodiments of this application, the soft-start circuit 10 can not only play the role of soft start, but also reduce the size it occupies and reduce the cost.

[0084] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although the preferred embodiment has been disclosed above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A soft-start circuit, characterized in that, The soft-start circuit is used for start-up control during the process of the power module supplying power to the load device. The soft-start circuit includes a controller, a switching unit, a freewheeling unit, a current detection unit, an energy storage unit, and an energy release unit. The controller is coupled to the switching unit and the current detection unit; the switching unit is coupled between the first end of the power module and the energy release unit, and the energy release unit is coupled to the second end of the energy storage unit; the first end of the freewheeling unit is coupled to the second end of the power module and the first end of the energy storage unit, and the second end of the freewheeling unit is coupled to the node between the switching unit and the energy release unit; The current detection unit is coupled between the freewheeling unit and the switching unit; When the difference between the voltage of the energy storage unit and the input voltage of the power supply module is greater than the voltage threshold, During a first time period, the controller controls the switching unit to operate in PWM mode; wherein, during the first time period, the controller controls the switching unit to be turned on so that the power module charges the energy storage unit via the energy release unit; during a second time period, the controller controls the switching unit to be turned off so that the energy release unit discharges the energy storage unit via the freewheeling unit; the first time period and the second time period constitute one working cycle within the first time period, and the first time period in the latter working cycle is longer than the first time period in the former working cycle; During the second time period following the first time period, the controller detects the current through the current detection unit and controls the on / off state of the switching unit based on the detected current until the difference between the voltage of the energy storage unit and the input voltage of the power module is less than the voltage threshold. When the difference between the voltage of the energy storage unit and the input voltage of the power module is less than the voltage threshold, the controller controls the switching unit to turn on, so as to control the power module to supply power to the load device.

2. The soft-start circuit as described in claim 1, characterized in that, The controller is coupled to the energy storage unit to detect the voltage of the energy storage unit.

3. The soft-start circuit as described in claim 1 or 2, characterized in that, The switching unit is a transistor or a relay.

4. The soft-start circuit as described in claim 1 or 2, characterized in that, The energy storage unit is a capacitor, and the energy release unit is an inductor.

5. The soft-start circuit as described in claim 1 or 2, characterized in that, The freewheeling unit includes a diode, the cathode of which is coupled to the second terminal of the power module and the first terminal of the energy storage unit, and the anode of which is coupled to the node between the switching unit and the energy release unit.

6. A soft-start circuit, characterized in that, The soft-start circuit is used for start-up control during the process of the power module supplying power to the load device. The soft-start circuit includes a controller, a switching unit, a freewheeling unit, a current detection unit, an energy storage unit, and an energy release unit. The controller is coupled to the switching unit and the current detection unit; the switching unit is coupled between the first terminal of the power module and the first terminal of the energy storage unit; the first terminal of the energy release unit is coupled to the second terminal of the power module and the first terminal of the freewheeling unit; the second terminal of the energy release unit is coupled to the second terminal of the energy storage unit; the second terminal of the freewheeling unit is coupled to the node between the switching unit and the first terminal of the energy storage unit; the current detection unit is coupled between the freewheeling unit and the second terminal of the power module. When the difference between the voltage of the energy storage unit and the input voltage of the power supply module is greater than the voltage threshold, During a first time period, the controller controls the switching unit to operate in PWM mode; wherein, during the first time period, the controller controls the switching unit to be turned on so that the power module charges the energy storage unit via the energy release unit; during a second time period, the controller controls the switching unit to be turned off so that the energy release unit discharges the energy storage unit via the freewheeling unit; the first time period and the second time period constitute one working cycle within the first time period, and the first time period in the latter working cycle is longer than the first time period in the former working cycle; During the second time period following the first time period, the controller detects the current through the current detection unit and controls the on / off state of the switching unit based on the detected current until the difference between the voltage of the energy storage unit and the input voltage of the power module is less than the voltage threshold. When the difference between the voltage of the energy storage unit and the input voltage of the power module is less than the voltage threshold, the controller controls the switching unit to turn on, so as to control the power module to supply power to the load device.

7. A control method for a soft-start circuit, characterized in that, The soft-start circuit includes a controller, a switching unit, a freewheeling unit, a current detection unit, an energy storage unit, and an energy release unit; Wherein, the controller is coupled to the switching unit and the current detection unit; the switching unit is coupled between a first terminal of the power module and the energy release unit, and the energy release unit is coupled to a second terminal of the energy storage unit; the first terminal of the freewheeling unit is coupled to a second terminal of the power module and a first terminal of the energy storage unit, and the second terminal of the freewheeling unit is coupled to a node between the switching unit and the energy release unit; the current detection unit is coupled between the freewheeling unit and the switching unit; or... The controller is coupled to the switching unit and the current detection unit; the switching unit is coupled between the first terminal of the power module and the first terminal of the energy storage unit; the first terminal of the energy release unit is coupled to the second terminal of the power module and the first terminal of the freewheeling unit; the second terminal of the energy release unit is coupled to the second terminal of the energy storage unit; the second terminal of the freewheeling unit is coupled to the node between the switching unit and the first terminal of the energy storage unit; the current detection unit is coupled between the freewheeling unit and the second terminal of the power module. The control method for the soft-start circuit includes: When the difference between the voltage of the energy storage unit and the input voltage of the power supply module is greater than the voltage threshold, During the first time period, the switching unit is controlled to operate in PWM mode; wherein, during the first time period, the switching unit is controlled to be turned on to control the power module to charge the energy storage unit; during the second time period, the switching unit is controlled to be turned off to control the energy release unit to discharge the energy storage unit through the freewheeling unit; wherein, the first time period and the second time period constitute one working cycle within the first time period, and the first time period in the later working cycle is longer than the first time period in the earlier working cycle; During the second time period following the first time period, the controller detects the current through the current detection unit and controls the on / off state of the switching unit based on the detected current until the difference between the voltage of the energy storage unit and the input voltage of the power module is less than the voltage threshold. When the difference between the voltage of the energy storage unit and the input voltage of the power module is less than the voltage threshold, the switching unit is controlled to turn on, so as to control the power module to supply power to the load device.

8. The control method for the soft-start circuit as described in claim 7, characterized in that, Also includes: Detect the voltage of the energy storage unit; If the voltage of the energy storage unit is equal to the input voltage of the power supply device, or if the voltage difference between the voltage of the energy storage unit and the input voltage of the power supply device is less than a preset threshold, the switching unit is controlled to always operate in the on state.

9. A power supply device, characterized in that, The power supply equipment includes a power module and a soft-start circuit as described in any one of claims 1-6.

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