CN107800117A - A kind of protection circuit against input over-voltage with upper electric Inrush current restraining function - Google Patents

Abstract

The invention discloses an input overvoltage protection circuit with a power-on surge current suppression function, including a power supply circuit, a peak detection circuit, a peak voltage sampling comparison circuit, a switching tube current sampling comparison circuit at the moment of power-on, a discharge resistor, a low The on-resistance switch tube and the reference voltage source; the power supply circuit includes a first diode, a first capacitor and a voltage limiting bias circuit; the peak detection circuit includes a second diode and a second capacitor; the peak voltage sampling comparison circuit includes a first A comparator, a first resistor and a second resistor; the switching tube current sampling comparison circuit at the moment of power-on includes a second comparator, a third resistor and a fourth resistor. It can be seen that the overvoltage protection of the present application operates quickly and can suppress the power-on surge current; the overvoltage protection circuit and the power-on surge current suppression circuit are organically combined, and the power switch tube and the power supply circuit are shared, the number of components is small, and the cost is low. Therefore, the problem of input overvoltage protection is solved, and the power-on surge current can be suppressed.

Description

An input overvoltage protection circuit with power-on surge current suppression function

technical field

The invention relates to the technical field of switching power supplies, in particular to an input overvoltage protection circuit with a power-on surge current suppression function.

Background technique

At present, most DC-DC converter control chips provide overvoltage protection function. This function can force the converter to stop working when abnormal high voltage occurs in the power grid, but it cannot solve the problem of overvoltage of the input filter capacitor, nor can it solve the problem of the output of the APFC circuit. Filter capacitor overvoltage problem. For this reason, some converters add a mains detection circuit to trigger the relay action when the mains is abnormal, and disconnect the input circuit of the converter. However, the reliability of the electromagnetic relay is poor and the action is slow. The input filter capacitor still bears the instantaneous high voltage, which has not been completely solved. security risks.

In addition, the voltage at the terminal of the filter capacitor rises from zero at the moment of power-on. If it is just near the maximum value of the sinusoidal alternating current when the power is turned on, there will be a transient high current of up to hundreds of amperes at the moment of power-on, which will affect the power grid and the AC- Devices in the input channel of the DC converter, such as fuses, power frequency rectifier diodes, and filter capacitors, have caused severe high-current shocks. At present, in order to suppress the power-on surge current of the switching power supply, methods such as connecting an NTC thermistor in series before or after the power frequency rectification circuit of the converter, an AC zero-crossing trigger, or connecting a power resistor in parallel with a relay can be used. However, although the above measures can control the power-on surge current within a certain range, they all have certain defects. For example, the cost of connecting NTC thermistors in series is the lowest, but the AC input current always flows through the thermistors during normal operation, resulting in high power consumption of NTC resistors, high temperature and high current for a long time, and more seriously, power failure Finally, you must wait for the NTC resistor to cool down to normal temperature before powering on, otherwise the thermistor will lose its power-on surge current suppression function, reducing the reliability of the AC-DC converter; the AC zero-crossing trigger method requires a thyristor Rectifier, and additional auxiliary power supply, AC zero-crossing detection circuit, high cost, complicated circuit; although the parallel connection of power resistor and electromagnetic relay can better solve the power-on surge current and the current limit during the normal operation of the converter. The resistance power consumption is contradictory, but the relay pulls in a large current, the reliability of the mechanical contact is poor, and the volume is large.

Therefore, how to not only solve the problem of input overvoltage protection, but also suppress the power-on surge current is a problem to be solved in this field.

Contents of the invention

The object of the present invention is to provide an input overvoltage protection circuit with a power-on surge current suppression function, so as to solve the problem of input overvoltage protection and suppress the power-on surge current of the converter.

In order to achieve the above purpose, the present invention provides an input overvoltage protection circuit with a power-on surge current suppression function, including a power supply circuit, a peak detection circuit, a peak voltage sampling comparison circuit, a switching tube current sampling comparison circuit at the moment of power-on, and a first Five resistors, low on-resistance switch tube and reference voltage source;

The power supply circuit includes a first diode, a first capacitor and a voltage limiting bias circuit; the peak detection circuit includes a second diode and a second capacitor; the peak voltage sampling comparison circuit includes a first comparator, The first resistor and the second resistor; the switching tube current sampling comparison circuit at the moment of power-on includes a second comparator, a third resistor and a fourth resistor;

The anode of the first diode is connected to the N terminal of the mains, and the cathode is respectively connected to the input terminal of the voltage limiting bias circuit and one end of the first capacitor; the other end of the first capacitor is connected to the rectifier circuit connected to the negative end of the second diode; the positive pole of the second diode is connected to the positive end of the rectifier circuit, and the negative pole is connected to one end of the second capacitor; the other end of the second capacitor is connected to the negative end of the rectifier circuit end connected;

One end of the first resistor is connected to the cathode of the second diode, and the other end is connected to the inverting input end of the first comparator; one end of the second resistor is connected to the negative end of the rectifier circuit connected, and the other end is connected to the non-inverting input end of the first comparator; one end of the fourth resistor is connected to the negative end of the rectifier circuit, and the other end is respectively connected to one end of the third resistor, the fifth One end of the resistor is connected to the first end of the low on-resistance switch tube; the other end of the third resistor is connected to the inverting input end of the second comparator;

The output terminal of the voltage limiting bias circuit is respectively connected to the output terminal of the first comparator, the output terminal of the second comparator, the other terminal of the fifth resistor and the low on-resistance switch tube. The second end is connected; the third end of the low on-resistance switch tube is connected to the post-stage converter; the input overvoltage protection circuit is connected to the negative end of the rectifier circuit and the primary side of the post-stage converter. Between potential reference points;

Wherein, the fifth resistor is a discharge resistor; the reference voltage source is used to provide a reference reference potential for the first comparator and the second comparator, and the first comparator and the second comparator The comparators share the same set of reference voltage sources or use independent reference voltage sources.

Optionally, the peak detection circuit is incorporated into the power supply circuit to obtain a peak detection power supply circuit; the peak detection power supply circuit includes the first diode, the second diode, the voltage limiting bias Set the circuit and the first capacitor;

The anode of the first diode is connected to the L terminal of the commercial power supply, and the cathode is respectively connected to the input end of the voltage limiting bias circuit, one end of the first capacitor, and the cathode of the second diode ; The anode of the second diode is connected to the N terminal of the mains.

Optionally, a sixth resistor is also included, one end of the sixth resistor is respectively connected to the inverting input end of the first comparator and the other end of the first resistor, and the other end is connected to the low on-resistance The third end of the switch tube is connected to each other.

Optionally, a seventh resistor connected in series before or after the second diode is also included.

Optionally, a lightning protection device is further included, and the two ends of the lightning protection device are respectively connected to the first end and the third end of the low on-resistance switch tube.

Optionally, the lightning protection device is a piezoresistor or a discharge tube.

Optionally, the low on-resistance switch tube is a low on-resistance N-channel power MOS tube or a low saturation voltage drop IGBT tube.

Optionally, the voltage limiting bias circuit is a passive circuit or an active circuit.

Optionally, when the post-stage converter is the APFC converter, the anode of the first diode is connected to the positive terminal of the rectification circuit.

Applying the above-mentioned technical solution, when the mains power is abnormally high, the low on-resistance switch tube can be turned off, so that the converter is in a suspended state, and the requirements for the withstand voltage of the switch tube inside the converter are low, and the overvoltage protection action is rapid, and The power-on surge current can be suppressed; the over-voltage protection circuit and the power-on surge current suppressing circuit are organically combined, and the power switch tube and the power supply circuit are shared, the number of components is small, and the cost is low. Therefore, the problem of input overvoltage protection is solved, and the power-on surge current can be suppressed.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

FIG. 1 is a schematic diagram of a specific implementation of an input overvoltage protection circuit with a power-on surge current suppression function provided by an embodiment of the present invention;

FIG. 2 is another schematic diagram of an input overvoltage protection circuit with a power-on surge current suppression function provided by an embodiment of the present invention;

3 is another schematic diagram of an input overvoltage protection circuit with a power-on surge current suppression function provided by an embodiment of the present invention;

FIG. 4 is a schematic diagram of a specific application of an input overvoltage protection circuit with a power-on surge current suppression function provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment one

Please refer to FIG. 1. FIG. 1 is a schematic diagram of a specific implementation of an input overvoltage protection circuit with a power-on surge current suppression function provided by an embodiment of the present invention. The input overvoltage protection circuit 1 includes a power supply circuit 11, a peak detection circuit, peak voltage sampling comparison circuit 12, switch tube current sampling comparison circuit 13 at the moment of power-on, fifth resistor 14, low on-resistance switch tube 15 and reference voltage source;

The power supply circuit 11 includes a first diode D1, a first capacitor C1 and a voltage limiting bias circuit; the peak detection circuit includes a second diode D2 and a second capacitor C2; the peak voltage sampling comparison circuit 12 includes a first comparator CP1 , the first resistor R1 and the second resistor R2; the switching tube current sampling comparison circuit 13 includes a second comparator CP2, a third resistor R3 and a fourth resistor R4 at the moment of power-on;

The anode of the first diode D1 is connected to the N terminal of the mains, and the cathode is respectively connected to the input terminal of the voltage limiting bias circuit and one end of the first capacitor C1; the other end of the first capacitor C1 is connected to the negative end of the rectifier circuit 2 ; The anode of the second diode D2 is connected to the positive end of the rectifier circuit 2, and the cathode is connected to one end of the second capacitor C2; the other end of the second capacitor C2 is connected to the negative end of the rectifier circuit 2;

One end of the first resistor R1 is connected to the negative pole of the second diode D2, and the other end is connected to the inverting input end of the first comparator CP1; one end of the second resistor R2 is connected to the negative end of the rectifier circuit 2, and the other end is connected to the negative end of the rectifier circuit 2. The non-inverting input terminal of the first comparator CP1 is connected; one terminal of the fourth resistor R4 is connected with the negative terminal of the rectifier circuit 2, and the other terminal is respectively connected with one terminal of the third resistor R3, one terminal of the fifth resistor R5, and the low on-resistance switching tube 15 is connected to the first end; the other end of the third resistor R3 is connected to the inverting input end of the second comparator CP2;

The output end of the voltage limiting bias circuit is respectively connected to the output end of the first comparator CP1, the output end of the second comparator CP2, the other end of the fifth resistor R5 and the second end of the low on-resistance switch tube 15; The third end of the on-resistance switch tube 15 is connected to the post-stage converter; the input overvoltage protection circuit is connected between the negative terminal A of the rectifier circuit 2 and the common potential reference point B on the primary side of the post-stage converter 3;

Among them, the fifth resistor is a discharge resistor; the reference voltage source is used to provide the reference reference potential for the first comparator and the second comparator, and the first comparator and the second comparator share the same set of reference voltage sources or use independent the reference voltage source. The negative terminal of the reference voltage source V _ref shown in the figure is connected to the negative terminal A of the rectification circuit 2 , and the positive terminal is connected to the non-inverting input terminal of the comparator.

It can be understood that the above-mentioned low on-resistance switch tube may be a low on-resistance N-channel power MOS tube, a low saturation voltage drop IGBT tube, or other devices with similar functions, which are not limited herein. And the first end of the above-mentioned low on-resistance switch tube may refer to the source of the N-channel power MOS transistor, the second end may refer to the gate of the N-channel power MOS transistor, and the third end may refer to the N-channel power MOS transistor. The drain of the power MOS tube.

The above-mentioned voltage limiting bias circuit may be a passive circuit or an active circuit. The above-mentioned rectification circuit may be but not limited to a rectification bridge.

The above-mentioned post-stage converter can be specifically an AC-DC converter with various topologies such as flyback, forward or APFC, for example, a DC-DC converter and an APFC converter with a Boost topology, and the post-stage converter can also be And connect an input filter capacitor 4.

The following will take FIG. 1 as an example to introduce the working process of the input overvoltage protection circuit with power-on surge current suppression function provided by the embodiment of the present invention.

At the moment of power-on, the terminal voltage of the filter capacitor C1 is zero, which ensures that the switch tube 15 is in a cut-off state at the moment of power-on. If the input voltage, the terminal voltage of the input filter capacitor 4, the current of the switch tube 15, the terminal voltage of the switch tube 15, and the reference voltage connected to the non-inverting input terminals of the comparators CP1 and CP2 are respectively V _IN , i _DS , V _C3 , V _BA , V _ref , at the moment of power-on, if the input voltage V _IN is large, because the input filter capacitor 4 is not charged or the residual charge is small, its terminal voltage V _C3 is small, so that the voltage V _BA between BA is large, when i _DS × R ₄ When ≥V _ref , the comparator CP2 outputs a low level, and the current forced to flow through the switch tube 15 is limited to , thereby suppressing the power-up current. In this way, the maximum current i _DS of the switching tube at the moment of power-on can be limited by selecting the resistor R4 and the reference voltage V _ref . For example, V _ref is taken as 1.25V, R4 is taken as 0.13Ω, In order to ensure the normal operation of the converter, the instantaneous suppression current i _DS is taken as 1.5 times of the peak value of the maximum operating current when the power is turned on.

After the switch tube 15 is turned on, it is always in the conduction state. Since the switch tube 15 has a small conduction internal resistance, it does not affect the operation of the subsequent DC-DC converter.

At the moment of power-on, if the input voltage V _IN is high, the switch tube 15 will not conduct, and the converter input filter capacitor C3 and the DC-DC converter itself will obviously not bear the risk of overvoltage; during normal operation, if the input voltage V The sudden abnormal high voltage of _IN is detected by the input mains peak detection circuit, then the comparator CP1 will output a low level, forcing the switching tube 15 to turn off quickly, and the input high voltage will be applied to both ends of the switching tube 15, avoiding the abnormal high voltage Applied to the input filter capacitor C3 and the DC-DC converter to realize the input overvoltage protection function. Obviously, the input overvoltage protection voltage value is determined by the ratio of resistors R1 and R2 OK, that is, when the input voltage The switch tube 15 is turned off quickly, and is in an overvoltage protection state, and the DC-DC converter does not work. After the overvoltage disappears, the potential of the output terminal of the input mains peak detection circuit gradually decreases. When the potential of the inverting terminal of the comparator CP1 is lower than the potential of the non-inverting terminal, the comparator CP1 outputs a high level, triggering the switch tube 15 to conduct, thereby realizing overvoltage recovery operation.

After power off, the AC input voltage V _IN disappears, no current flows through the rectifier diode, and the filter capacitor C1 discharges. As long as the circuit parameters are properly selected, it can ensure that the switch tube 15 enters the cut-off state quickly after power off, so the power-on time short. For example, as long as the size of the bleeder resistor R5 is moderate, it can ensure that the switch tube enters the cut-off state within 100 ms after power off.

In this embodiment, the circuit can turn off the low on-resistance switch tube when the mains power is abnormally high, so that the converter is in a suspended state, and the requirements for the withstand voltage of the switch tube inside the converter are low, and the overvoltage protection action is rapid , and can suppress the power-on surge current; the overvoltage protection circuit and the power-on surge current suppression circuit are organically combined, and the power switch tube and the power supply circuit are shared, the number of components is small, and the cost is low. Therefore, the problem of input overvoltage protection is solved, and the power-on surge current can be suppressed.

Embodiment two

Based on the first embodiment above, referring to another schematic diagram of the input overvoltage protection circuit with power-on surge current suppression function shown in FIG. 2 , in this embodiment, the peak detection circuit is incorporated into the power supply circuit to obtain a peak detection power supply circuit; The power supply circuit includes a first diode D1, a second diode D2, a voltage limiting bias circuit and a first capacitor C1; the anode of the first diode D1 is connected to the L terminal of the mains, and the negative pole is respectively connected to the voltage limiting bias The input end of the circuit, one end of the first capacitor C1, and the cathode of the second diode D2 are connected; the anode of the second diode D2 is connected to the N terminal of the mains.

That is to say, compared with the first embodiment, the difference of this embodiment is that two rectifier diodes are provided in the power supply circuit 11, which are D1 and D2 respectively, and D1 and D2 form a full-wave rectification, and the filter can be appropriately increased. The capacity of capacitor C1. In this way, it can be understood that the peak detection circuit is incorporated into the power supply circuit, so that the peak voltage holding capacitor C2 can be saved, so that the input overvoltage protection circuit has fewer components, lower cost, and simpler structure.

Embodiment Three

Based on any of the above-mentioned embodiments, referring to another schematic diagram of an input overvoltage protection circuit with a power-on surge current suppression function shown in FIG. One terminal of R1 is respectively connected to the inverting input terminal of the first comparator CP1 and the other terminal of the first resistor R1, and the other terminal is connected to the third terminal of the low on-resistance switch tube 15.

The inverting input terminal of the comparator CP1 is connected to the third terminal of the low on-resistance switch tube 15 to form a positive feedback path, which can prevent the low-on-resistance switch tube 15 from operating when the input voltage V _IN is near the overvoltage protection point. Possible opening and closing phenomena. For example, when the input voltage V _IN is just equal to the overvoltage protection voltage, the comparator CP1 outputs a low level, causing the switch tube Q to be turned off, and the potential of point B rises, which is applied to the inverting terminal of the comparator CP1 through the resistor R6 to make the comparator The potential of the inverting terminal of the device CP1 is further increased, so that even if the peak voltage of the peak detection circuit peak voltage holding capacitor C2 terminal voltage drops slightly, the switch tube Q will not enter the conduction state.

Further, the input overvoltage protection circuit may further include a seventh resistor R7 connected in series before or after the second diode D2. That is, one end of the seventh resistor R7 can be connected to the input end, and the other end can be connected to the anode of the second diode D2, or one end can be connected to the cathode of the second diode D2, and the other end can be connected to one end of the capacitor C2.

Under the impact of lightning voltage, the output voltage of the peak detection circuit rises sharply, causing the MOS tube to fail to enter the conduction state quickly after the lightning impact voltage pulse. Therefore, the current limiting resistor R7 is connected in series before or after the peak detection diode D2 to limit the peak detection circuit. increase in output voltage.

Further, the input overvoltage protection circuit may further include a lightning protection device, and the two ends of the lightning protection device are respectively connected to the first end and the third end of the low on-resistance switch tube. Furthermore, the lightning protection device is a piezoresistor VR or a discharge tube.

For example, as shown in Figure 3, in order to avoid overvoltage damage to the MOS tube under the impact of the lightning strike voltage and to provide a lightning strike current path, the varistor VR is connected in parallel between the drain D of the MOS tube and the negative terminal of the rectifier bridge 2 . In this way, under the impact of the lightning voltage, the current flowing through the switch tube rises rapidly. When i _DS × R ₄ ≥ V _ref , the comparator CP2 outputs a low level, and the voltage of the DS pole of the MOS tube rises rapidly. When the V _BA voltage exceeds When the varistor VR clamps the voltage, the varistor VR is quickly turned on, providing a path for the lightning surge current.

Embodiment Four

Based on any of the above embodiments, referring to the specific application schematic diagram of the input overvoltage protection circuit with power-on surge current suppression function shown in FIG. 4, the input overvoltage circuit may also include a filter capacitor C3, one end of the filter capacitor C3 The positive end of the rectifier circuit 2 is connected, and the other end is connected with the third end of the low on-resistance switch tube 15;

The post-stage converter 3 is connected to both ends of the filter capacitor 4 in parallel; the post-stage converter is a DC-DC converter or an APFC converter with Boost topology; when the post-stage converter is an APFC converter, the first diode The positive terminal of the rectifier is connected to the positive terminal of the rectifier circuit.

As shown in Figure 4, it is an APFC converter with the input overvoltage circuit applied to Boost topology. In the figure, the anode of the rectifier diode D1 is connected to the positive end of the rectifier bridge 2. At this time, the rectifier diode D1 has dual functions of isolation and detection, preventing the discharge of the filter capacitor C1 through the DC-DC converter. In other embodiments, the anode of the rectifier diode D1 may also be connected to the N terminal or the L terminal of the AC input line.

Each embodiment in the description is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The input overvoltage protection circuit with power-on surge current suppression function provided by the present invention has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (9)

1. An input overvoltage protection circuit with a power-on surge current suppression function, characterized in that it includes a power supply circuit, a peak detection circuit, a peak voltage sampling comparison circuit, a switching tube current sampling comparison circuit at the moment of power-on, and a fifth resistor , low on-resistance switching tube and reference voltage source; The power supply circuit includes a first diode, a first capacitor and a voltage limiting bias circuit; the peak detection circuit includes a second diode and a second capacitor; the peak voltage sampling comparison circuit includes a first comparator, The first resistor and the second resistor; the switching tube current sampling comparison circuit at the moment of power-on includes a second comparator, a third resistor and a fourth resistor; The anode of the first diode is connected to the N terminal of the mains, and the cathode is respectively connected to the input terminal of the voltage limiting bias circuit and one end of the first capacitor; the other end of the first capacitor is connected to the rectifier circuit connected to the negative end of the second diode; the positive pole of the second diode is connected to the positive end of the rectifier circuit, and the negative pole is connected to one end of the second capacitor; the other end of the second capacitor is connected to the negative end of the rectifier circuit end connected; One end of the first resistor is connected to the cathode of the second diode, and the other end is connected to the inverting input end of the first comparator; one end of the second resistor is connected to the negative end of the rectifier circuit connected, and the other end is connected to the non-inverting input end of the first comparator; one end of the fourth resistor is connected to the negative end of the rectifier circuit, and the other end is respectively connected to one end of the third resistor, the fifth One end of the resistor is connected to the first end of the low on-resistance switch tube; the other end of the third resistor is connected to the inverting input end of the second comparator; The output terminal of the voltage limiting bias circuit is respectively connected to the output terminal of the first comparator, the output terminal of the second comparator, the other terminal of the fifth resistor and the low on-resistance switch tube. The second end is connected; the third end of the low on-resistance switch tube is connected to the post-stage converter; the input overvoltage protection circuit is connected to the negative end of the rectifier circuit and the primary side of the post-stage converter. Between potential reference points; Wherein, the fifth resistor is a discharge resistor; the reference voltage source is used to provide a reference reference potential for the first comparator and the second comparator, and the first comparator and the second comparator The comparators share the same set of reference voltage sources or use independent reference voltage sources. 2. The input overvoltage protection circuit with power-on surge current suppression function according to claim 1, characterized in that, the peak detection circuit is incorporated into the power supply circuit to obtain a peak detection power supply circuit; the peak detection circuit The power supply circuit includes the first diode, the second diode, the voltage limiting bias circuit and the first capacitor; The anode of the first diode is connected to the L terminal of the commercial power supply, and the cathode is respectively connected to the input end of the voltage limiting bias circuit, one end of the first capacitor, and the cathode of the second diode ; The anode of the second diode is connected to the N terminal of the mains. 3. The input overvoltage protection circuit with power-on surge current suppression function according to claim 1, further comprising a sixth resistor, one end of the sixth resistor is respectively connected to the first comparator The inverting input end is connected to the other end of the first resistor, and the other end is connected to the third end of the low on-resistance switch tube. 4. The input overvoltage protection circuit with power-on surge current suppression function according to claim 1, further comprising a seventh resistor connected in series before or after the second diode. 5. The input overvoltage protection circuit with power-on surge current suppression function according to claim 1, further comprising a lightning protection device, the two ends of the lightning protection device are respectively connected to the low conduction resistance The first end of the switch tube is connected to the third end. 6 . The input overvoltage protection circuit with power-on surge current suppression function according to claim 5 , wherein the lightning protection device is a piezoresistor or a discharge tube. 7. The input overvoltage protection circuit with a power-on surge current suppression function according to any one of claims 1 to 6, wherein the low on-resistance switching tube is a low on-resistance N-channel power MOS tube or low saturation pressure drop IGBT tube. 8. The input overvoltage protection circuit with power-on surge current suppression function according to claim 7, wherein the voltage limiting bias circuit is a passive circuit or an active circuit. 9. The input overvoltage protection circuit with power-on surge current suppression function according to claim 7, characterized in that, when the subsequent stage converter is the APFC converter, the first diode The positive pole of is connected with the positive terminal of the rectification circuit.