Commercial power start-up soft start circuit of high-frequency voltage stabilizer and UPS (Uninterrupted Power Supply)

Abstract

The utility model provides a mains supply start-up soft start circuit of a high-frequency voltage stabilizer and a UPS (Uninterrupted Power Supply). The mains supply start-up soft start circuit comprises a mains supply detection circuit, a main control IC (Integrated Circuit), a soft start control circuit, a BUS capacitor charging circuit, and a BUS voltage detection circuit and one or more BUS capacitors which are electrically connected with the BUS capacitor circuit, the mains supply detection circuit and the voltage detection circuit are electrically connected with the main control IC; the soft start control circuit is electrically connected between the mains supply detection circuit and the BUS capacitor charging circuit; the main control IC comprises a first control pin, a second control pin and a third control pin; the soft start control circuit comprises a first relay, a second relay electrically connected with the first relay, an electronic switch connected with the second relay, and a current-limiting resistor; the first relay is electrically connected to the first control pin, and the electronic switch is electrically connected to the second control pin; a current-limiting resistor and BUS capacitor charging circuit; and the first relay is also electrically connected with the BUS capacitor charging circuit. The UPS is applied to a mains supply soft start circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, in particular to a mains power soft start circuit of a high-frequency voltage stabilizer and a UPS power supply. Background Art

[0002] When a high-frequency voltage regulator is powered on from mains power, the sudden surge in input voltage often generates a large inrush current, potentially damaging internal circuit components. Therefore, a soft-start circuit is required to charge the bus capacitor when the high-frequency voltage regulator is powered on from mains power. Typical products use a control IC combined with a thyristor rectifier, or the control IC charges the bus capacitor via a DC / DC converter. Both of these startup methods require complex circuitry and utilize numerous components, resulting in higher product costs. Utility Model Content

[0003] In view of this, it is necessary to propose a mains power soft start circuit of a high frequency voltage stabilizer and a UPS power supply.

[0004] An embodiment of the utility model provides a mains power soft-start circuit for a high-frequency voltage regulator, which includes a mains power detection circuit, a main control IC, a soft-start control circuit, a BUS capacitor charging circuit, a BUS voltage detection circuit electrically connected to the BUS capacitor circuit, and one or more BUS capacitors; the BUS capacitor charging circuit is used to charge the BUS capacitor; the BUS voltage detection circuit is used to detect the BUS capacitor, the mains power detection circuit and the voltage detection circuit are both electrically connected to the main control IC, and the soft-start control circuit is electrically connected between the mains power detection circuit and the BUS capacitor charging circuit.

[0005] The main control IC includes a first control pin, a second control pin, and a third control pin;

[0006] The soft start control circuit includes a first relay, a second relay electrically connected to the first relay, an electronic switch connected to the second relay, and a current limiting resistor; the first relay is electrically connected to the first control pin, and the electronic switch is also electrically connected to the second control pin; the current limiting resistor is connected to the BUS capacitor charging circuit; the first relay is also electrically connected to the BUS capacitor charging circuit; when the main control IC receives the mains signal detected by the mains detection circuit, the first control pin outputs a first level to the first relay to electrically connect the first relay and the second relay, and the second control pin outputs a second level to the electronic switch to electrically connect the second relay to the current limiting resistor, so that the mains charges the BUS capacitor charging circuit; the main control IC detects through the BUS voltage detection circuit and when the BUS voltage detection circuit detects that the BUS capacitor is charged to a preset voltage, the second control pin outputs a third level and the first control pin outputs a fourth level, so that the first relay is directly connected to the BUS capacitor charging circuit for charging, and the second relay is disconnected from the circuit where the current limiting resistor is located.

[0007] Furthermore, the first level, the second level, the third level, and the fourth level are respectively a low level, a high level, a low level, and a high level.

[0008] Furthermore, the mains power soft start circuit of the high-frequency voltage regulator also includes a mains PFC boost circuit, which is electrically connected to the BUS capacitor charging circuit and the main control IC.

[0009] Furthermore, the relay includes two springs, one spring can be selectively coupled to the second relay to electrically connect the first relay and the second relay; the other spring can be selectively coupled to the BUS capacitor charging circuit.

[0010] Furthermore, the AC power soft start circuit of the high-frequency voltage regulator also includes a fuse and an inductor, one end of the fuse is selectively electrically connected to a spring of the second relay; one end of the inductor is connected to the other end of the fuse, and the other end is electrically connected to the BUS capacitor charging circuit.

[0011] Furthermore, the mains PFC boost circuit is electrically connected between the inductor and the BUS capacitor charging circuit.

[0012] Furthermore, the current limiting resistor includes a first resistor and a second resistor connected in series, an end of the first resistor not connected to the second resistor is electrically connected to a spring of the second relay, and an end of the second resistor not connected to the first resistor is coupled between the fuse and the first relay.

[0013] Furthermore, the electronic switch is a triode, the base of the triode is electrically connected to the second control pin, the collector of the triode is electrically connected to the second relay, and the emitter of the triode is grounded.

[0014] Furthermore, the AC power soft start circuit of the high-frequency voltage stabilizer further includes a diode, which is electrically connected to the collector and emitter of the transistor.

[0015] Furthermore, a UPS power supply is applied to a mains power soft start circuit of a high frequency voltage stabilizer.

[0016] The novel high-frequency voltage regulator startup circuit utilizes a switching relay and a current-limiting resistor, and is controlled by a main control IC to achieve the soft-start function of the BUS capacitor of the high-frequency voltage regulator when powered on by mains power, thereby saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 This is a schematic diagram of the mains-powered soft-start circuit framework for an embodiment of the utility model.

[0019] Figure 2 This is a mains power detection circuit diagram of an embodiment of the utility model.

[0020] Figure 3 This is a soft start control circuit diagram of an embodiment of the utility model.

[0021] Figure 4 This is a BUS capacitor charging circuit diagram of an embodiment of the utility model.

[0022] Figure 5 This is a BUS voltage detection circuit diagram of an embodiment of the utility model.

[0023] Figure 6 This is a PFC boost circuit diagram of an embodiment of the utility model.

[0024] Figure 7 This is a circuit diagram of a soft starter for a mains BUS power supply according to an embodiment of the utility model.

[0025] Figure 8 This is a working logic diagram of the first stage of the mains BUS soft start in an embodiment of the utility model.

[0026] Figure 9 This is a working logic diagram of the second stage of the mains BUS soft start in an embodiment of the utility model.

[0027] Figure 10 This is a working logic diagram of the mains boost stage provided by an embodiment of the utility model.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship described in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0031] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0032] To provide a clearer and more accurate understanding of the present invention, the following detailed description is provided with reference to the accompanying drawings. The accompanying drawings illustrate exemplary embodiments of the present invention, with like reference numerals representing like elements. It should be understood that the scales shown in the accompanying drawings are not those of the actual implementation of the present invention. These scales are for illustrative purposes only and are not drawn to scale.

[0033] Please see Figure 1 , which is a schematic diagram of the mains-powered soft-start circuit framework of an embodiment of the present application. The mains-powered soft-start circuit 1 includes a mains detection circuit 10, a main control IC 20, a soft-start control circuit 30, a bus capacitor charging circuit 40, a bus voltage detection circuit 50, and a PFC boost circuit 60. Furthermore, it includes one or more bus capacitors 70, and the bus capacitor charging circuit 40 is used to charge the bus capacitors 70.

[0034] The AC power detection circuit 10 and the BUS voltage detection circuit 50 are both electrically connected to the main control IC 20. The soft start control circuit 30 is electrically connected between the AC power detection circuit 10 and the BUS capacitor charging circuit 40. The AC power PFC boost circuit 60 is electrically connected between the BUS capacitor charging circuit 40 and the main control IC 20. The main control IC 20 is also provided with a voltage detection pin 200. The BUS voltage detection circuit 40 is configured with a voltage detection point BUS++, which is directly electrically connected to the voltage detection pin 200.

[0035] Combined with reference Figure 2 The mains detection resistor circuit 10 is a key component in the high-frequency voltage regulator's startup circuit, responsible for detecting the mains input signal. It typically consists of a series of precision resistors that accurately measure the mains voltage level and transmit this information to the main control IC 20. For example, a metal film resistor can be used as the mains detection resistor. Auxiliary circuitry can also be added to compensate for voltage fluctuations caused by load changes.

[0036] The main control IC 20 is the core of the entire high-frequency voltage regulator startup circuit. It includes a first control pin 201, a second control pin 202, and a second control pin 203. Depending on the actual situation, it outputs a first level 2000, a second level 2001, a third level 2002, and a fourth level 2003 (low level, high level, low level, and high level, respectively). The main control IC is typically a microcontroller or dedicated control chip with precise control capabilities. In this embodiment, the main control IC is an MCU.

[0037] See Figure 3The soft start control circuit 30 includes a first relay RY1, a second relay RY2 electrically connected to the first relay RY1, an electronic switch 300 connected to the second relay RY2, a current-limiting resistor 301, a fuse F2, and an inductor L1. The current-limiting resistor 301 is composed of a first resistor R9 and a second resistor R10 connected in series. The relay includes two springs, one of which can selectively couple with the second relay RY2 to electrically connect the first relay RY1 and the second relay RY2, and the other spring can selectively couple with the BUS capacitor charging circuit 40. The end of the first resistor R9 not connected to the second resistor R10 is electrically connected to a spring of the second relay RY2, and the end of the second resistor R10 not connected to the first resistor R9 is coupled between the fuse F2 and the first relay RY1. One end of the fuse F2 is selectively electrically connected to a spring of the second relay RY2. One end of the inductor L1 is connected to the other end of the fuse F2, and the other end is electrically connected to the BUS capacitor charging circuit 40. Electronic switch 300 can be a transistor Q1, equipped with a suitable diode ZD1 to ensure consistent current flow. The base of transistor Q1 is electrically connected to second control pin 202, the collector is electrically connected to second relay RY2, and the emitter is grounded. Diode ZD1 is electrically connected to the collector and emitter of transistor Q1.

[0038] The first relay RY1 and the second relay RY2 each have distinct roles. The second relay RY2 is primarily used to limit current during the initial phase of mains power-up, while the first relay RY1 is used to switch circuits during normal power supply. The second relay RY2 is activated during the startup phase and, by connecting in series with the current-limiting resistor 301, effectively limits the current flowing into the line, preventing damage to the equipment due to excessive current. Once the BUS capacitor 70 charges to the set voltage, the main control IC 20 issues a command to close the second relay RY2 and connect the first relay RY1, placing the system in normal operating mode. To ensure relay reliability and durability, relays are typically designed with a latching function, meaning that only a single control signal is required to maintain the relay in the on or off state until the next opposing control signal is received.

[0039] Transistor Q1 acts as an electronic switch, controlled by a level signal from the main control IC 20, to control the on / off of the second relay RY2. When the base receives a high level signal, transistor Q1 turns on, energizing the coil of the second relay RY2, thereby controlling the on / off of the second relay RY2.

[0040] Current-limiting resistor 301 is connected in series after the second relay RY2. Its primary function is to limit current during the soft-start phase to prevent damage to the system due to sudden current fluctuations. The selection of current-limiting resistor 301 is crucial and should be determined based on the system's maximum allowable current and the expected startup time. For example, if the circuit needs to complete startup in a short time, a smaller resistance value should be selected; conversely, if a slower startup process is desired, a larger resistance value can be selected. Furthermore, current-limiting resistors are typically high-power, low-temperature-coefficient types to ensure good performance even under long operating times or with fluctuating ambient temperatures. By properly configuring the current-limiting resistor parameters, the peak current during startup can be effectively reduced without affecting normal circuit operation.

[0041] Fuse F2 mainly provides circuit protection to prevent overcurrent damage. Inductor F1 is mainly used for filtering to ensure circuit stability.

[0042] See Figure 4 The BUS capacitor charging circuit 40 includes a BUS capacitor 70 and rectifier diodes D1 and D2. The BUS capacitor 70 includes C1, C2, C3, and C7. The BUS capacitors C1 and C7 are connected in parallel between the output terminals of the rectifier diodes D1 and D2 and the load. C2 and C3 are used to store electrical energy and stabilize the output voltage.

[0043] See Figure 5 The BUS voltage detection circuit 50 includes multiple BUS detection resistors R4, R5, R6, R17, R18, and R19. The BUS detection resistors R4, R5, R6, R17, R18, and R19 are connected to the two ends of the BUS capacitors C2 and C3 to detect the voltage of the BUS capacitors C2 and C3 and transmit the voltage feedback signal to the main control IC 20.

[0044] See Figure 6 The PFC boost circuit 60 is electrically connected between the inductor L1 and the BUS capacitor charging circuit 40. The PFC boost circuit 60 includes a PFC control IC, a PFC switch 600, a current transformer CT1, an inductor L1, and a rectifier bridge REC1. The PFC switch 600 can be a field-effect transistor Q2. The output of the PFC control IC is electrically connected to the gate of Q2, the drain of Q2 is connected to the positive output of REC1, and the source of Q2 is connected to the current transformer. L1 is electrically connected to REC1.

[0045] See Figure 7 , is a circuit diagram of a mains powered soft starter in an embodiment of the utility model.

[0046] After the mains power is connected, the mains power detection circuit 10 detects the mains power signal and transmits it to the main control IC 20. After the main control IC 20 detects the mains power signal, the first control pin 201 outputs a first voltage level 2000 to the first relay RY1, electrically connecting RY1 to the second relay RY2. The second control pin 202 also outputs a second voltage level 2001 to the electronic switch, electrically connecting RY2 to the current-limiting resistor R9. This allows the mains power to charge the bus capacitors C2 and C3 via the bus capacitor charging circuit 40. When the bus voltage detection circuit detects that the bus capacitors have reached a preset voltage, the main control IC 20 outputs a third voltage level 2002 from the second control pin 202 and a fourth voltage level 2003 from the first control pin 201, directly connecting RY1 to the bus capacitor charging circuit for charging and disconnecting the circuit connecting RY2 to R9. The mains power then charges the bus capacitors C2 and C3 directly via RY1, fuse F2, inductor L1, and rectifier diodes D1 and D2. At this point, the PFC control IC begins operating, issuing a high-frequency PWM signal to control PFC switch Q2, regulating the input current waveform and improving the power factor. Rectifier bridges REC1 and CT1 work in conjunction with components RY1, F2, and L1 to ensure efficient rectification and filtering of the input current. The circuit enters a stable operating state, and bus capacitors C2 and C3 maintain a stable DC voltage output, providing power to the load. Main control IC 20 continuously monitors the bus capacitor voltage and status to ensure stable circuit operation.

[0047] In this embodiment, the relay utilizes a low internal resistance design, and its contacts are made of silver alloy to reduce contact resistance, lower energy loss, and thus improve the efficiency of the startup circuit. The current-limiting resistor is a metal film resistor with a low temperature coefficient and high heat resistance, enabling more precise current limiting during the soft-start phase and ensuring a smooth startup process. The transistor is a high-speed switching transistor, with a small resistor connected in series between its base and emitter to reduce radio frequency interference and ensure that the high-level signal from the main control IC can accurately control the transistor's conduction state. The fuse is a fast-acting fuse, and its rated current is precisely calculated to match the maximum operating current of the entire startup circuit. This allows for rapid circuit disconnection in the event of an overcurrent, protecting other components from damage. The inductor is wound around a ferrite core, exhibiting excellent high-frequency characteristics and effectively filtering out high-frequency noise while maintaining a low DC resistance, reducing energy loss and improving the overall efficiency of the startup circuit. The rectifier bridge uses ultra-fast recovery diodes to reduce reverse recovery time, lower switching losses, and improve rectification efficiency. Low-impedance copper busbars are used to connect the rectifier bridge and current transformer to minimize energy loss at the connection. The BUS capacitors utilize aluminum electrolytic capacitors with high ripple current tolerance. Multiple capacitors are connected in parallel to increase the total capacity, improving energy storage capacity and output voltage stability, ensuring stable operation of the high-frequency regulator.

[0048] See Figure 8 , is a first-stage working logic diagram of the soft start control circuit of an embodiment of the present application. When the high-frequency voltage regulator is connected to the mains power, the mains power signal (usually AC power) enters the circuit through the input port INPUT-L1. The main control IC 20 detects the presence of the mains power and the possible voltage level by using a voltage divider network composed of capacitors (R4, R5, R6, R27, R18, R19) in the detection circuit. These resistor combinations are used to reduce the high-voltage mains power signal to a voltage range that can be safely read by the main control IC 20.

[0049] When the main control IC 20 detects the mains power signal, it sends a low-level signal to the MAN-RLY port. Since the MAN-RLY port is typically connected to the control terminal of a relay or similar switch, a low-level signal means the relay remains inactive (i.e., inactive). Therefore, the relay controlled by MAN-RLY remains open, unaffecting further transmission of the mains power signal. The mains power signal continues to flow through the circuit, passing through the first relay RY1. After RY1 closes, the mains power signal is transmitted to the input terminal of the second relay RY2. The main control IC 20 sends a high-level signal to the base of transistor Q1, turning on transistor Q1 and allowing current to flow through its collector and emitter. In this circuit, transistor Q1 acts as a switch. Its conduction causes the drive coil of RY2 to receive sufficient current to generate a magnetic field, which in turn attracts the spring of RY2, connecting the mains power signal to the current-limiting resistors (R9, R10). After passing through the current-limiting resistor 300, the mains power signal passes through F2 and L1 before entering the rectifier bridge formed by D1 and D2. The rectifier bridge converts AC power to DC power, which is then filtered and stored in bus capacitors C2 and C3. The voltage on the bus capacitors slowly rises during this process. The main control IC 20 detects the bus voltage via bus voltage detection circuit 50. Based on the detected voltage level, the main control IC 20 adjusts its control strategy to ensure output voltage stability and safety.

[0050] See Figure 9 , is the second-stage working logic diagram of the soft start control circuit of an embodiment of the present application. After the BUS capacitor is boosted in the first stage, the main control IC 20 detects that the voltage value of the BUS capacitors C2 and C3 reaches the first threshold value through BUS++, and the main control MCU sends a low-level signal to the I / P-RLY signal, causing the transistor Q1 to turn off. This action disconnects the charging path through RY2 and the current-limiting resistor 300. At the same time, the main control IC 20 sends a high-level signal to the coil of RY1, connecting the switch spring of RY1 to F2. In this way, a new charging path is formed, charging the BUS capacitors C2 and C3 through RY1, F2, D1 and D2. Under the new charging path, the BUS capacitors C2 and C3 continue to charge, and the voltage rises further. The main control IC 20 continues to monitor the voltage state of the BUS capacitor through the BUS++ line to ensure that it reaches the final operating voltage safely and effectively.

[0051] See Figure 10, is a logic diagram of the PFC boost circuit operation in an embodiment of the present application. The main control IC 20 first detects the voltage on the BUS capacitor. When the BUS capacitor voltage needs to be further increased, the main control IC 20 sends a signal to the PFC control IC. After receiving the signal from the main control IC 20, the PFC control IC generates a high-frequency PWM signal. This PWM signal is used to control the on and off state of the PFC switch Q2. By precisely controlling the switching state of Q2, power transmission can be effectively regulated, achieving power factor correction and boost functions. Mains power enters the circuit through RY1 and F2. The current then passes through inductor L1, is rectified by rectifier bridge REC1, and then passes through switch Q2. Under the control of Q2, the current is periodically switched on and off, forming a high-frequency pulse current. Current sensing element CT1 monitors the current through Q2, allowing the PFC control IC to adjust the duty cycle of the PWM signal based on current feedback, thereby precisely controlling the switching time of Q2.

[0052] The rectified current flows through D1 and D2 to charge bus capacitors C2 and C3. The PFC control IC not only generates a PWM signal to control Q2 but also adjusts the PWM signal's duty cycle based on the bus voltage and CT1 current sensing feedback. This closed-loop control mechanism ensures that the voltage on the bus capacitors remains stable, meeting the requirements of the downstream DC / AC module. This control process maintains a stable voltage on bus capacitors C2 and C3, providing reliable power input to the downstream DC / AC module and ensuring the proper operation and efficient performance of the entire circuit system.

[0053] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present application. Thus, if such modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.

[0054] The above examples are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims

1. A mains-powered soft-start circuit for a high-frequency voltage stabilizer, characterized in that: The circuit includes a mains detection circuit, a main control IC, a soft start control circuit, a BUS capacitor charging circuit, a BUS voltage detection circuit electrically connected to the BUS capacitor circuit, and one or more BUS capacitors; The BUS capacitor charging circuit is used to charge the BUS capacitor; the BUS voltage detection circuit is used to detect the BUS capacitor, the mains detection circuit and the voltage detection circuit are both electrically connected to the main control IC, and the soft start control circuit is electrically connected between the mains detection circuit and the BUS capacitor charging circuit; The main control IC includes a first control pin, a second control pin, and a third control pin; The soft start control circuit includes a first relay, a second relay electrically connected to the first relay, an electronic switch connected to the second relay, and a current limiting resistor; the first relay is electrically connected to the first control pin, and the electronic switch is also electrically connected to the second control pin; the current limiting resistor is connected to the BUS capacitor charging circuit; the first relay is also electrically connected to the BUS capacitor charging circuit; when the main control IC receives a mains signal detected by the mains detection circuit, the first control pin outputs a first level to the first relay to electrically connect the first relay and the second relay, and the second control pin outputs a second level to the electronic switch to electrically connect the second relay to the current limiting resistor, so that the mains charges the BUS capacitor for the BUS capacitor charging circuit; the main control IC detects through the BUS voltage detection circuit that the BUS capacitor is charged to a preset voltage, the second control pin outputs a third level and the first control pin outputs a fourth level, so that the first relay is directly connected to the BUS capacitor charging circuit for charging, and the second relay is disconnected from the circuit where the current limiting resistor is located.

2. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 1, characterized in that: The first level, the second level, the third level, and the fourth level are respectively a low level, a high level, a low level, and a high level.

3. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 1, characterized in that: The mains power soft start circuit of the high-frequency voltage regulator further includes a mains PFC boost circuit, and the mains PFC boost circuit is electrically connected to the BUS capacitor charging circuit and the main control IC.

4. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 1, characterized in that: The relay includes two springs, one of which can be selectively coupled to the second relay to electrically connect the first relay and the second relay; and the other spring can be selectively coupled to the BUS capacitor charging circuit.

5. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 1, characterized in that: The AC power soft start circuit of the high-frequency voltage regulator also includes a fuse and an inductor, one end of the fuse is selectively electrically connected to a spring of the second relay; one end of the inductor is connected to the other end of the fuse, and the other end is electrically connected to the BUS capacitor charging circuit.

6. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 5, characterized in that: The mains PFC boost circuit is electrically connected between the inductor and the BUS capacitor charging circuit.

7. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 5, characterized in that: The current limiting resistor includes a first resistor and a second resistor connected in series, an end of the first resistor not connected to the second resistor is electrically connected to a spring of the second relay, and an end of the second resistor not connected to the first resistor is coupled between the fuse and the first relay.

8. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 1, characterized in that: The electronic switch is a triode, the base of the triode is electrically connected to the second control pin, the collector of the triode is electrically connected to the second relay, and the emitter of the triode is grounded.

9. The AC power soft start circuit of the high frequency voltage stabilizer according to claim 8, characterized in that: The mains power soft start circuit of the high-frequency voltage regulator further includes a diode, which is electrically connected to the collector and emitter of the transistor.

10. A UPS power supply, characterized in that: The UPS power supply uses a mains power soft start circuit of the high frequency voltage stabilizer as described in any one of claims 1-9.

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