A large inrush current impact suppression circuit for a high-power switching power supply
By using a surge current suppression circuit with a current-limiting resistor and an inductor, combined with a relay bypass design, the problem of surge current impact at the moment of power-on of high-power switching power supplies is solved, achieving fast response, low power consumption and high reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- DONGGUAN CITY YOHOO ELECTRONIC TECH CO LTD
- Filing Date
- 2025-07-10
- Publication Date
- 2026-07-21
AI Technical Summary
The surge current generated during the power-on of existing high-power switching power supplies can damage devices. Existing suppression methods suffer from high power consumption, slow response, and design contradictions.
By using a current-limiting resistor and an inductor to limit the rate of current rise, and by bypassing the current-limiting resistor through a relay, the relay is controlled by the power supply's own voltage, simplifying the control process and achieving a fast response.
It effectively suppresses surge current at startup, reduces component heating and power consumption, and improves system safety and reliability.
Smart Images
Figure CN224538050U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a circuit, specifically a surge current suppression circuit for high-power switching power supplies. Background Technology
[0002] With social development and the improvement of industrial automation, high-power switching power supplies have been widely used in various power electronic devices, industrial equipment, communication equipment, and new energy fields. High-power switching power supplies typically have advantages such as high power rating, stable output, small size, and high efficiency. However, because they generally contain large-capacity electrolytic capacitors, transformers, and other inductive components, a large surge current impact will occur at the moment the switching power supply is turned on due to capacitor charging and the current build-up process of inductive components.
[0003] In existing technologies, a current-limiting resistor is often connected in series at the power input to suppress inrush current, thereby limiting the rate of rise of the initial current. However, this approach has the following drawbacks: if the current-limiting resistor is kept energized for a long time, it will lead to significant power consumption and cause the resistor element to overheat or even be damaged; furthermore, the surge suppression effect is often closely related to the choice of resistor value. If the resistance value is too large, it will affect the normal startup of the power supply, while if the resistance value is too small, it will not effectively suppress the inrush current, resulting in a design contradiction.
[0004] To address these issues, some existing technologies introduce relays or electronic switches to bypass the current-limiting resistor. This involves using the current-limiting resistor to limit inrush current during the initial power-on phase, and then short-circuiting the resistor via the relay or electronic switch once the power supply voltage is established. However, existing bypass circuit control methods are relatively complex, some relying on external control circuits or involving lengthy monitoring times. Bypassing may only be completed after the instantaneous inrush current has already damaged some components, resulting in problems such as untimely protection and slow response speed. Utility Model Content
[0005] To address the aforementioned issues, this invention provides a surge current suppression circuit for high-power switching power supplies. This circuit effectively suppresses surge current during startup while reducing circuit power consumption and component heating, thereby enhancing the reliability and safety of the switching power supply.
[0006] This utility model is achieved through the following technical solution: a surge current suppression circuit for high-power switching power supplies, comprising:
[0007] The input terminal is used to connect to the AC power input;
[0008] Fuse F1 is connected in series between the input terminal and the inside of the circuit;
[0009] A surge suppression unit, comprising a metal oxide varistor MOV1 and an X capacitor CX1 connected in parallel with the MOV1;
[0010] The current limiting unit is activated, which includes a current limiting resistor R1 and an inductor LF1 connected in series, to limit the rate of current rise at the moment of power-on.
[0011] The bypass switching unit includes a relay K1 and a switching transistor Q2 that controls the on and off of the relay K1. The control terminal of the Q2 is connected to the power supply voltage VCC and is connected to VCC through a resistor R3. The conduction of the Q2 causes the relay K1 to close, thereby bypassing the current limiting resistor R1.
[0012] The rectifier bridge ABM410 is connected to the output terminal of the current limiting unit and is used to convert AC power into DC power.
[0013] The high-voltage filter capacitor CE1 is connected to the output terminal of the rectifier bridge ABM410;
[0014] The main switching circuit, including the switching device Q1 and its driving circuit, is used to control the energy transfer of the subsequent transformer TRINS-1.
[0015] The output rectifier and filter circuit includes a rectifier diode D2 and a filter capacitor CE3, which is used to output DC voltage.
[0016] As a preferred technical solution, the current-limiting resistor R1 has a resistance value of 1Ω to 20Ω, which is used to limit the peak value of the surge current at the moment of power-on.
[0017] As a preferred technical solution, the relay K1 closes with a delay after the circuit is energized, so as to ensure that the surge current is completely attenuated before bypassing the current limiting resistor R1.
[0018] As a preferred technical solution, the switching transistor Q2 is an NPN bipolar transistor or an N-channel MOSFET.
[0019] As a preferred technical solution, the rectifier bridge ABM410 is a single-phase rectifier bridge composed of four diodes.
[0020] As a preferred technical solution, the inductance value of the inductor LF1 is 0.1mH to 10mH.
[0021] As a preferred technical solution, the MOV1 is a metal oxide varistor with a varistor voltage range of 270V to 470V.
[0022] As a preferred technical solution, the main switching circuit uses PWM control to control the energy of the transformer TRINS-1.
[0023] The beneficial effects of this invention are: at the moment of power-on, this circuit limits the rise rate of the input current through the cooperation of the current-limiting resistor and the inductor, avoiding excessive surge current generated when the large-capacity capacitor is charging, thereby reducing the impact on the subsequent rectifier bridge and switching devices, and helping to extend the service life of the devices.
[0024] This circuit is designed with a bypass switching unit, which controls the transistor to drive the relay to short-circuit the current-limiting resistor. After the power supply is working normally, the current-limiting resistor is removed from the circuit to avoid power consumption and heat generation caused by continuous high current, thereby improving the power supply efficiency.
[0025] This circuit uses the VCC voltage generated by the power supply itself as a drive signal to control the transistor to turn on or off, thereby controlling the relay to close or open. It has a simple structure, fast response speed, and reliable control, avoiding complex external detection or delay circuits.
[0026] This circuit ensures rapid establishment of normal operating current while effectively avoiding current surges during power-on of high-power switching power supplies, thus contributing to improved overall system safety and reliability. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation
[0029] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.
[0030] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.
[0031] like Figure 1 As shown, this utility model provides a surge current suppression circuit for high-power switching power supplies. In this specific embodiment, the structure and working principle of the circuit will be described in detail with reference to the accompanying drawings.
[0032] This surge current suppression circuit includes an input terminal for connecting to an AC power input, which in a specific implementation can be a mains power input terminal. The input terminal has two ends connected to the live wire (L) and the neutral wire (N), respectively. A fuse F1 is connected in series between the input terminal and the internal circuitry to cut off the power supply in the event of a short circuit or overcurrent fault, protecting the safety of subsequent circuit components.
[0033] The surge suppression unit is located at the rear end of fuse F1 and includes a metal oxide varistor (MOV1) and an X capacitor (CX1) connected in parallel with MOV1. Under normal circuit operation, MOV1 is in a high-impedance state. When an overvoltage occurs at the input terminal, MOV1 quickly conducts, absorbing and releasing the surge energy, thereby protecting subsequent circuits from high-voltage impacts. CX1 is used to absorb high-frequency interference signals, reducing the impact of electromagnetic interference on circuit performance. Furthermore, the MOV1 is selected as a metal oxide varistor with a varistor voltage range of 270V to 470V, which can be selected according to the voltage level of the actual application scenario to meet the surge protection requirements of different power grid environments.
[0034] The startup current limiting unit is connected after the surge suppression unit and includes a current limiting resistor R1 and an inductor LF1 connected in series. At startup, due to the charging or establishment of a current magnetic field by the large-capacity electrolytic capacitors and inductive devices, a large surge current is generated. At this time, the current first passes through the current limiting resistor R1 and the inductor LF1, which suppresses the rate of current rise and prevents damage to downstream circuit components due to the instantaneous large current surge. Specifically, the resistance value of the current limiting resistor R1 is preferably 1Ω to 20Ω to suppress the peak value of the surge current while ensuring normal power supply startup. The inductance value of the inductor LF1 is preferably 0.1mH to 10mH, which provides effective current change rate limitation without causing excessive voltage drop to the normal power frequency operating current.
[0035] To reduce circuit power consumption and heat generation from the current-limiting resistor during normal power supply operation, this circuit incorporates a bypass switching unit. This unit includes a relay K1 and a switching transistor Q2 that controls the on / off state of K1. The control terminal of Q2 is connected to the power supply voltage VCC via a resistor R3. During the initial power-on phase, before a stable VCC voltage is established, Q2 is off, relay K1 remains open, and current flows through the current-limiting resistor R1 and inductor LF1, achieving current limiting. As the VCC voltage gradually builds up, VCC provides base current or gate drive voltage to Q2 through resistor R3, turning Q2 on. This causes relay K1 to close, bypassing the current-limiting resistor R1. This design effectively prevents prolonged high current flow through the current-limiting resistor R1, avoiding overheating or even damage, thus improving circuit efficiency and reliability. Furthermore, relay K1 preferably closes after a certain delay following circuit power-on to ensure the surge current has completely decayed before bypassing the current-limiting resistor R1, thereby avoiding the risk of inrush current from premature bypassing. In a specific implementation, the switching transistor Q2 can be an NPN bipolar transistor or an N-channel MOSFET. Different device types can be selected according to design requirements to match the control current or voltage requirements.
[0036] Following the bypass switching unit, the circuit includes a rectifier bridge ABM410, whose input is connected to the output of the current limiting unit, used to convert AC to DC. In this embodiment, the rectifier bridge ABM410 is a single-phase rectifier bridge composed of four diodes. By rectifying the positive and negative half-cycles of the AC voltage separately, a pulsating DC voltage is obtained for use by subsequent circuits. A high-voltage filter capacitor CE1 is connected to the output of the rectifier bridge. CE1 is used to filter out voltage fluctuations in the rectified output, making the DC voltage more stable.
[0037] Furthermore, the circuit includes a main switching circuit, comprising a switching device Q1 and its driving circuit. The switching device Q1 is preferably a high-voltage power MOSFET or IGBT, used for high-frequency switching on and off, thereby enabling controlled energy transfer between the primary side and the transformer TRINS-1. The main switching circuit employs PWM control to control the energy of the transformer TRINS-1, adjusting the output voltage or power by changing the duty cycle of the PWM wave to meet different load requirements.
[0038] On the secondary side of transformer TRINS-1, the circuit includes an output rectifier and filter circuit, which comprises a rectifier diode D2 and a filter capacitor CE3. D2 rectifies the induced voltage on the transformer's secondary side, while CE3 filters the rectified voltage to output a stable DC voltage for the load.
[0039] With the above structure, the surge current suppression circuit of this utility model can effectively suppress surge current at the moment of power-on, avoid damage to the device caused by transient surge current generated when charging a large-capacity capacitor, and at the same time, after the power supply is working normally, the current-limiting resistor is bypassed through the relay, reducing energy loss and heat generation of the resistive element, thereby improving the working efficiency and safety and reliability of the entire switching power supply system. It is particularly suitable for high-power switching power supply application scenarios.
[0040] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope defined in the claims.
Claims
1. A surge current suppression circuit for high-power switching power supplies, characterized in that, include: The input terminal is used to connect to the AC power input; Fuse F1 is connected in series between the input terminal and the inside of the circuit; A surge suppression unit, comprising a metal oxide varistor MOV1 and an X capacitor CX1 connected in parallel with the MOV1; The current limiting unit is activated, which includes a current limiting resistor R1 and an inductor LF1 connected in series, to limit the rate of current rise at the moment of power-on. The bypass switching unit includes a relay K1 and a switching transistor Q2 that controls the on and off of the relay K1. The control terminal of the Q2 is connected to the power supply voltage VCC and is connected to VCC through a resistor R3. The conduction of the Q2 causes the relay K1 to close, thereby bypassing the current limiting resistor R1. The rectifier bridge ABM410 is connected to the output terminal of the current limiting unit and is used to convert AC power into DC power. The high-voltage filter capacitor CE1 is connected to the output terminal of the rectifier bridge ABM410; The main switching circuit, including the switching device Q1 and its driving circuit, is used to control the energy transfer of the subsequent transformer TRINS-1. The output rectifier and filter circuit includes a rectifier diode D2 and a filter capacitor CE3, which is used to output DC voltage.
2. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The current-limiting resistor R1 has a resistance of 1Ω to 20Ω and is used to limit the peak surge current at the moment of power-on.
3. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The relay K1 closes with a delay after the circuit is powered on, so as to ensure that the surge current is completely attenuated before bypassing the current limiting resistor R1.
4. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The switching transistor Q2 is an NPN bipolar transistor or an N-channel MOSFET.
5. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The rectifier bridge ABM410 is a single-phase rectifier bridge composed of four diodes.
6. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The inductance value of the inductor LF1 is from 0.1mH to 10mH.
7. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The MOV1 is a metal oxide varistor with a varistor voltage range of 270V to 470V.
8. The surge current suppression circuit for high-power switching power supplies according to claim 1, characterized in that: The main switching circuit uses PWM control to control the energy of the transformer TRINS-1.