A surge protection circuit and method for a power factor correction circuit

Abstract

The present invention relates to a surge protection circuit and method for a power factor correction circuit. A constant current charging module is provided to charge an energy storage capacitor so that the voltage of the energy storage capacitor reaches a first threshold value. After the voltage of the energy storage capacitor reaches the first threshold value, a control and comparison module is used to compare the capacitor voltage value and the value of an AC power supply signal in a falling interval of each AC cycle, and a first control signal in a pulse form is generated when the difference between the capacitor voltage value and the value of the AC power supply signal is less than or equal to a second threshold value. Therefore, a rectifier module performs periodic and step-by-step energy charging on the energy storage capacitor according to the first control signal until the voltage of the energy storage capacitor rises to the peak value of the AC power supply signal, and a second control signal is generated by the control and comparison module. The rectifier module drives the power factor correction circuit according to the second control signal. The present invention performs step-by-step energy charging on the energy storage capacitor in multiple stages to avoid the energy storage capacitor from directly bearing high voltage, thereby protecting the energy storage capacitor.

Description

Technical Field

[0001] The invention belongs to the field of protection circuits, and in particular relates to a surge protection circuit and method for a power factor correction circuit. Background Art

[0002] Electronic circuit ports are usually connected to large-capacity energy storage capacitors, especially in power factor correction situations. When power is turned on, the initial voltage of the energy storage capacitor is zero. When a surge occurs, the energy storage capacitor directly bears the high voltage, thereby generating a large impact current, which can easily cause device failure. Summary of the invention

[0003] The invention provides a surge protection circuit and method for a power factor correction circuit, so as to solve the technical problem in the prior art that energy storage capacitors are prone to failure due to surges.

[0004] A surge protection circuit and method for a power factor correction circuit, used for surge protection of a power correction circuit, wherein an energy storage capacitor is provided at the output end of the power correction circuit, comprising:

[0005] A constant current charging module, wherein the input end of the constant current charging module is connected to an external AC power supply, and the output end and the collection end of the constant current charging module are connected to the energy storage capacitor; the constant current charging module is used to perform constant current charging on the energy storage capacitor according to the AC power supply signal, and to collect the voltage value of the energy storage capacitor, and to compare the voltage value of the energy storage capacitor with a preset first threshold value, and when the voltage value of the energy storage capacitor rises to the first threshold value, stop charging the energy storage capacitor;

[0006] A control and comparison module, wherein a first acquisition terminal of the control and comparison module is connected to an external AC power supply, and a second acquisition terminal of the control and comparison module is connected to the energy storage capacitor; the control and comparison module is used to perform a difference operation on the value of the AC power signal and the voltage value of the energy storage capacitor when the voltage value of the energy storage capacitor rises to a first threshold value and the AC power signal is in a falling interval of any cycle, and generate a first control signal when the difference between the value of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value; the control and comparison module is also used to generate a second control signal when the energy storage capacitor rises to a peak value of the AC power signal;

[0007] A rectifier module, wherein the input end of the rectifier module is connected to an external AC power supply, the output end of the rectifier module is connected to the input end of the power factor correction circuit and the energy storage capacitor, and the control end of the rectifier module is connected to the control and comparison module; the rectifier module is used to rectify the AC power supply signal according to the first control signal to obtain a first DC signal, and charge the energy storage capacitor according to the first DC signal; the rectifier module is also used to rectify the AC power supply signal according to the second control signal to obtain a second DC signal, and drive the power factor correction circuit according to the second DC signal.

[0008] In one embodiment of the present invention, the power factor correction circuit has a first input terminal and a second input terminal, and the rectifier module includes a first diode, a second diode, a first thyristor and a second thyristor;

[0009] The anode of the first diode is connected to the first input terminal of the power factor correction circuit, the cathode of the first diode is connected to the anode of the first thyristor, and the cathode of the first thyristor is connected to the second input terminal of the power factor correction circuit;

[0010] The anode of the second diode is connected to the first input terminal of the power factor correction circuit, the cathode of the second diode is connected to the anode of the second thyristor, and the cathode of the second thyristor is connected to the second input terminal of the power factor correction circuit;

[0011] The gate of the first thyristor and the gate of the second thyristor are connected to the control and comparison module, one end of the external AC power supply is connected between the cathode of the first diode and the anode of the first thyristor, and the other end of the external AC power supply is connected between the cathode of the second diode and the anode of the second thyristor.

[0012] In one embodiment of the present invention, the rectifier module is connected to the energy storage capacitor through a third diode; the anode of the third diode is connected to the cathode of the first thyristor and the cathode of the second thyristor, and the cathode of the third diode is connected to one end of the energy storage capacitor.

[0013] In one embodiment of the present invention, the constant current charging module includes:

[0014] a first comparing unit, wherein a collecting end of the first comparing unit is connected to the energy storage capacitor, the first comparing unit is used to collect a voltage value of the energy storage capacitor, and to compare the voltage value of the energy storage capacitor with a preset first threshold value, and to generate a stop charging signal when the voltage value of the energy storage capacitor rises to the first threshold value;

[0015] A constant current charging unit, wherein the input end of the constant current charging unit is connected to an external power supply, the output end of the constant current charging unit is connected to the energy storage capacitor, and the control end of the constant current charging unit is connected to the output end of the comparison unit; the constant current charging unit is used to perform constant current charging on the energy storage capacitor according to an AC power supply signal; the constant current charging unit is also used to stop charging the energy storage capacitor according to the stop charging signal.

[0016] In one embodiment of the present invention, the control and comparison module includes:

[0017] a second comparing unit, wherein a first collecting end of the second comparing unit is connected to an external AC power supply, a second collecting end of the second comparing unit is connected to the energy storage capacitor, and the second comparing unit is used to perform a difference operation on the value of the AC power supply signal and the voltage value of the energy storage capacitor when the voltage value of the energy storage capacitor rises to a first threshold value and the AC power supply signal is in a falling interval of any cycle;

[0018] A control unit, the control unit is connected to the output end of the second comparison unit, the control unit is used to generate a first control signal when the difference between the peak value of the current cycle of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value; the control unit is also used to generate a second control signal when the energy storage capacitor rises to the peak value of the AC power signal.

[0019] In one embodiment of the present invention, the power factor correction circuit has a first output terminal and a second output terminal, one end of the energy storage capacitor is connected to the first output terminal of the power factor correction circuit, and the other end of the energy storage capacitor is connected to the second output terminal of the power factor correction circuit.

[0020] In an embodiment of the present invention, the duration of the first control signal is shorter than the period of the AC power signal.

[0021] The present invention also provides a surge protection method for a power factor correction circuit, comprising:

[0022] Performing constant current charging on the energy storage capacitor preset in the power factor correction circuit according to the AC power supply signal, collecting the voltage value of the energy storage capacitor, comparing the voltage value of the energy storage capacitor with a preset first threshold value, and stopping charging the energy storage capacitor when the voltage value of the energy storage capacitor rises to the first threshold value;

[0023] When the voltage value of the energy storage capacitor rises to a first threshold value and the AC power signal is in a falling interval of any cycle, a difference operation is performed on the value of the AC power signal and the voltage value of the energy storage capacitor, and when the difference between the value of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value, a first control signal is generated; the AC power signal is rectified according to the first control signal to obtain a first DC signal, and the energy storage capacitor is charged according to the first DC signal;

[0024] When the energy storage capacitor rises to the peak value of the AC power signal, a second control signal is generated; the AC power signal is rectified according to the second control signal to obtain a second DC signal, and the power factor correction circuit is driven according to the second DC signal.

[0025] The present invention provides a surge protection circuit and method for a power factor correction circuit, which have the following beneficial effects: a constant current charging module is set to charge an energy storage capacitor so that the voltage of the energy storage capacitor reaches a first threshold value; after the voltage of the energy storage capacitor reaches the first threshold value, a control and comparison module is used to compare the capacitor voltage value and the value of an AC power supply signal in a falling interval of each AC cycle, and a first control signal in a pulse form is generated when the difference between the capacitor voltage value and the value of the AC power supply signal is less than or equal to a second threshold value, and the first control signal is generated in each cycle, so that a rectifier module performs periodic and step-by-step charging of the energy storage capacitor according to the first control signal until the voltage of the energy storage capacitor rises to the peak value of the AC power supply signal, and a second control signal is generated by the control and comparison module, and the rectifier module drives the power factor correction circuit according to the second control signal; the present invention performs step-by-step charging of the energy storage capacitor through multiple stages to avoid the energy storage capacitor directly bearing high voltage, thereby protecting the energy storage capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is an exemplary structure diagram of a conventional series resistance method in an embodiment of the present invention;

[0027] Figure 2 is a structural diagram of an exemplary anti-surge protection circuit of a power factor correction circuit in an embodiment of the present invention;

[0028] Figure 3 is a structural schematic diagram of an exemplary constant current charging module in an embodiment of the present invention;

[0029] Figure 4 is a schematic structural diagram of an exemplary control and comparison module in an embodiment of the present invention;

[0030] Figure 5 is an implementation flow chart of an exemplary surge protection circuit of a power factor correction circuit in an embodiment of the present invention;

[0031] Figure 6 It is a waveform diagram of an implementation of an exemplary surge protection circuit of a power factor correction circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0034] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present invention; however, it is apparent to one skilled in the art that embodiments of the present invention may be practiced without these specific details.

[0035] First of all, it should be noted that the power factor correction circuit is also called FPC (Power Factor Correction) circuit. The power factor refers to the relationship between effective power and total power consumption (apparent power), that is, the ratio of effective power divided by total power consumption (apparent power). Basically, the power factor can measure the degree to which electricity is effectively used. The larger the power factor value, the higher the power utilization rate.

[0036] like Figure 1 As shown, the general power factor correction circuit adopts the series resistance method. In the traditional series resistance method structure, during the startup phase, the energy storage capacitor directly bears the high voltage, thereby generating a large impact current, which easily causes the capacitor device to fail.

[0037] In view of the above technical problems, the purpose of this application is to solve Figure 1The shortcomings of the existing technologies such as the traditional series resistance method shown in the figure are overcome, the loss of the surge suppression circuit is reduced, the circuit volume and weight are reduced, and the system integration is improved; through reasonable control logic, the energy storage capacitor is first charged through the constant current module when power is turned on, and the controllable rectifier module works in pulse mode after the voltage of the energy storage capacitor is charged to a certain level. The main circuit starts to work when the energy storage capacitor is charged to a level close to the peak value of the input AC voltage, thereby reducing the surge current at startup and improving the circuit efficiency and reliability.

[0038] like Figure 2 As shown, a surge protection circuit of a power factor correction circuit provided in the present invention is used to perform surge protection on the power correction circuit. The output end of the power correction circuit is provided with a storage capacitor Co, including:

[0039] A constant current charging module, wherein the input end of the constant current charging module is connected to an external AC power supply, and the output end and the collection end of the constant current charging module are connected to the energy storage capacitor Co; the constant current charging module is used to perform constant current charging on the energy storage capacitor Co according to the AC power supply signal Vac, and to collect the voltage value of the energy storage capacitor Co, and to compare the voltage value of the energy storage capacitor Co with a preset first threshold value, and when the voltage value of the energy storage capacitor Co rises to the first threshold value, stop charging the energy storage capacitor Co;

[0040] A control and comparison module, wherein a first acquisition terminal of the control and comparison module is connected to an external AC power supply, and a second acquisition terminal of the control and comparison module is connected to the energy storage capacitor Co; the control and comparison module is used to compare the peak value of the current cycle of the AC power signal Vac with the voltage value of the energy storage capacitor Co when the voltage value of the energy storage capacitor Co rises to a first threshold value and the AC power signal Vac is in a falling interval of any cycle, and generate a first control signal when the difference between the value of the AC power signal Vac and the voltage value of the energy storage capacitor Co is less than or equal to a second threshold value; the control and comparison module is also used to generate a second control signal when the energy storage capacitor Co rises to the peak value of the AC power signal Vac;

[0041] Specifically, the control and comparison modules can adopt a general-purpose digital controller, which integrates functional modules such as A / D conversion and general IO control, can realize state monitoring, integrate flexible control algorithms, and reduce the complexity of control circuit design.

[0042] The rectifier module is composed of thyristors and diodes, which can achieve the function of controlling the charging time of AC voltage;

[0043] The constant current charging module provides constant current charging for the energy storage capacitor, reducing the voltage difference between the energy storage capacitor and the input voltage when the rectifier module starts working;

[0044] A rectifier module, wherein the input end of the rectifier module is connected to an external AC power supply, the output end of the rectifier module is connected to the input end of the power factor correction circuit and the energy storage capacitor Co, and the control end of the rectifier module is connected to the control and comparison module; the rectifier module is used to rectify the AC power signal Vac according to the first control signal to obtain a first DC signal, and charge the energy storage capacitor Co according to the first DC signal; the rectifier module is also used to rectify the AC power signal Vac according to the second control signal to obtain a second DC signal, and drive the power factor correction circuit according to the second DC signal.

[0045] Specifically, the power factor correction circuit can use a variety of topologies including boost circuit, buck circuit, flyback, etc., and can be flexibly configured according to the usage;

[0046] The implementation steps of this application are as follows:

[0047] Step 1: After the AC voltage is powered on, the rectifier module does not work, the constant current charging module charges the energy storage capacitor Co, and the control and comparison module detects the input AC voltage and the energy storage capacitor voltage;

[0048] Step 2: When the input voltage and the output voltage meet the conditions of the internal integrated algorithm of the control and comparison module, the control and comparison module controls the rectifier module to work in pulse mode. When the difference between the input AC voltage value and the voltage of the energy storage capacitor Co is small (less than or equal to the second threshold), the control and comparison module turns on the rectifier module for periodic rectification, thereby reducing the current amplitude of each cycle;

[0049] Step 3: When the rectifier module pulses to increase the voltage of the energy storage capacitor to the same level as the peak value of the AC voltage, the control and comparison module fully turns on the rectifier module according to the preset logic and enables the power factor correction circuit, and the circuit enters the main power working state.

[0050] The three steps correspond to the three stages of the work of this application. By charging the energy storage capacitor Co in stages, surge current is prevented from damaging the energy storage capacitor Co.

[0051] In one embodiment of the present invention, the power factor correction circuit has a first input terminal and a second input terminal, and the rectifier module includes a first diode D2, a second diode D3, a first thyristor D4 and a second thyristor D5;

[0052] The anode of the first diode D2 is connected to the first input terminal of the power factor correction circuit, the cathode of the first diode D2 is connected to the anode of the first thyristor D4, and the cathode of the first thyristor D4 is connected to the second input terminal of the power factor correction circuit;

[0053] The anode of the second diode D3 is connected to the first input terminal of the power factor correction circuit, the cathode of the second diode D3 is connected to the anode of the second thyristor D5, and the cathode of the second thyristor D5 is connected to the second input terminal of the power factor correction circuit;

[0054] The gate of the first thyristor D4 and the gate of the second thyristor D5 are connected to the control and comparison module, one end of the external AC power supply is connected between the cathode of the first diode D2 and the anode of the first thyristor D4, and the other end of the external AC power supply is connected between the cathode of the second diode D3 and the anode of the second thyristor D5.

[0055] Specifically, the AC power supply is connected to the midpoints A and B of the two bridge arms in the rectifier module through L1 and L2, and the cathode of the diode is connected to the anode connection point of the thyristor; the cathodes of the thyristors of the rectifier module are connected to each other and then connected to the positive input terminal of the power factor correction circuit, and are also connected to the anode of the diode D1; the anodes of the diodes of the rectifier module are connected to each other and then connected to the negative input terminal of the power factor correction circuit; the drive of the thyristor is initiated by digital control and then isolated and transmitted by a dedicated circuit; the positive output of the power factor correction circuit is connected to the positive terminal of the energy storage capacitor Co; the negative output of the power factor correction circuit is connected to the negative terminal of the energy storage capacitor and the cathode of the diode D1; the positive and negative terminals of the energy storage capacitor are connected to the positive and negative terminals of the subsequent load; the input AC input terminals L1 and L2 are connected to the input connection of the constant current charging circuit, and the output of the constant current charging circuit is connected to the positive terminal of the energy storage capacitor Co.

[0056] In this embodiment, a rectifier bridge is formed by thyristors and diodes, and the thyristor is turned on when the AC voltage value is in a decreasing range. The thyristor turn-off characteristic is utilized, which can greatly reduce the pulse current threshold.

[0057] In one embodiment of the present invention, the rectifier module is connected to the energy storage capacitor Co via a third diode D1; the anode of the third diode D1 is connected to the cathode of the first thyristor D4 and the cathode of the second thyristor D5, and the cathode of the third diode D1 is connected to the energy storage capacitor Co. In this embodiment, when the voltage Vo of the energy storage capacitor Co rises to the peak value of the AC power signal Vac, the potentials at both ends of the bypass (the branch where the third diode D1 is located) are the same, and the short-circuit effect of the bypass fails. At this time, when the control and comparison module controls the rectifier module to continue working, the DC signal obtained by rectification can be directly applied to the power factor correction circuit.

[0058] like Figure 3 As shown, in one embodiment of the present invention, the constant current charging module includes:

[0059] a first comparing unit, wherein the collecting end of the first comparing unit is connected to the energy storage capacitor Co, and the first comparing unit is used to collect the voltage value of the energy storage capacitor Co, and to compare the voltage value of the energy storage capacitor Co with a preset first threshold value, and to generate a stop charging signal when the voltage value of the energy storage capacitor Co rises to the first threshold value;

[0060] A constant current charging unit, wherein the input end of the constant current charging unit is connected to an external power supply, the output end of the constant current charging unit is connected to the energy storage capacitor Co, and the control end of the constant current charging unit is connected to the output end of the comparison unit; the constant current charging unit is used to perform constant current charging on the energy storage capacitor Co according to the AC power supply signal Vac; the constant current charging unit is also used to stop charging the energy storage capacitor Co according to the stop charging signal.

[0061] like Figure 4 As shown, in one embodiment of the present invention, the control and comparison module includes:

[0062] a second comparing unit, wherein a first collecting end of the second comparing unit is connected to an external AC power supply, a second collecting end of the second comparing unit is connected to the energy storage capacitor Co, and the second comparing unit is used to compare a peak value of a current cycle of the AC power signal Vac with the voltage value of the energy storage capacitor Co when the voltage value of the energy storage capacitor Co rises to a first threshold value and the AC power signal Vac is in a falling interval of any cycle;

[0063] A control unit, the control unit is connected to the output end of the second comparison unit, the control unit is used to generate a first control signal when the difference between the peak value of the current cycle of the AC power signal Vac and the voltage value of the energy storage capacitor Co is less than or equal to a second threshold value; the control unit is also used to generate a second control signal when the energy storage capacitor Co rises to the peak value of the AC power signal Vac.

[0064] In one embodiment of the present invention, the power factor correction circuit has a first output terminal and a second output terminal, one end of the energy storage capacitor Co is connected to the first output terminal of the power factor correction circuit, and the other end of the energy storage capacitor Co is connected to the second output terminal of the power factor correction circuit.

[0065] In an embodiment of the present invention, the duration of the first control signal is shorter than the period of the AC power signal Vac.

[0066] In some embodiments, a specific selection of a surge protection circuit for a power factor correction circuit is as follows:

[0067] Control and comparison module: ADP32F035QP64S, and peripheral circuits necessary for digital controller;

[0068] Thyristor: BT151D-800R;

[0069] Diode: S10M;

[0070] Capacitor Co: 1000μF (can be changed according to actual working conditions);

[0071] The current value of the constant current module is flexibly configured according to the energy storage capacitor value to adjust the charging time.

[0072] Through the surge suppression circuit and control algorithm proposed in the present invention, the startup timing of the power factor corrector can be well controlled, the problem of startup impact current can be effectively solved, and the reliability of the main circuit can be improved; at the same time, the circuit can smoothly realize the switching between the constant current source circuit and the main circuit, and has good dynamic and steady-state performance.

[0073] like Figure 5-Figure 6 As shown, the specific implementation process of a surge protection circuit of a power factor correction circuit of the present invention includes:

[0074] Vac is the input voltage, D1 is a surge current bypass diode to protect the main power tube of the power factor correction circuit, Co is the output energy storage capacitor, i1 is the output current of the constant current charging circuit, i2 is the current flowing through the bypass diode D1, and Vo is the voltage across the output capacitor Co.

[0075] When the AC voltage Vac is powered on, the constant current charging circuit works first to charge the energy storage capacitor Co, and the constant current charging module is provided with a first comparison unit. When the energy storage capacitor voltage Vo reaches a first threshold, the constant current charging module stops working, thereby preventing the output voltage from overshooting;

[0076] The control and comparison module detects the Vac and Vo values. When Vo reaches the first threshold value, and Vac is in the decreasing region, and the difference between the energy storage capacitor voltage Vo and the peak value of the AC voltage signal is less than or equal to the second threshold value, the control and comparison module controls the rectifier module to work in pulses. In order to reduce the pulse current i2, the thyristor is turned on when the AC voltage value is in the decreasing range. The thyristor turn-off characteristics are used, which can greatly reduce the pulse current threshold.

[0077] After a certain period of pulse charging of the rectifier module, the output voltage Vo rises to close to the peak value of the AC voltage. At this time, the control and comparison module completely turns on the rectifier module, and the rectifier module shapes the AC voltage into a double half-wave DC voltage to provide output for the power factor correction circuit. At this time, the digital controller enables the power factor correction circuit and the main power starts working.

[0078] In addition, the first threshold value can be adjusted according to actual needs, so as to increase or decrease the startup time of the power factor correction circuit.

[0079] The present invention discloses a surge protection circuit for a power factor correction circuit, which controls the charging current of the energy storage capacitor, solves the impact problem during the circuit startup process, and improves the reliability of the power device. By adopting a digital control method, rapid detection of the input current is achieved, and the current limiting protection function is realized. The control method circuit and method are simple. The rectifier module adopts a combination of thyristors and diodes. Due to the characteristics of the thyristors themselves, the main circuit has low requirements for control signals when working and high reliability. It is implemented using a general digital controller, which simplifies the circuit structure and reduces the design complexity. The invention has good practical value, high circuit integration, good consistency, and is easy to mass produce.

[0080] The present invention designs a controllable rectifier module, a constant current charging module and a control and comparison module, uses a digital controller to monitor the input and output states, and controls the rectifier bridge working logic through a built-in digital control algorithm, ultimately greatly reducing the surge current, reducing the current stress of the power device, and improving the circuit reliability. The constant current charging module is used to charge the energy storage capacitor and increase the initial voltage of the energy storage capacitor; the controllable rectifier bridge is one of the main power structures of the power factor circuit, which realizes the conversion of the AC voltage into a double half-wave DC voltage. Compared with the traditional uncontrolled rectifier bridge, it can realize the control of the switching moment, realize pulse charging, and reduce the surge current; the control and comparison module is the core of the surge current control, which can integrate a flexible control algorithm to control the circuit working timing, and can conveniently realize overvoltage, overcurrent and other protection functions.

[0081] The present invention provides a surge protection circuit for a power factor correction circuit. A constant current charging module is provided to charge an energy storage capacitor so that the voltage of the energy storage capacitor reaches a first threshold value. After the voltage of the energy storage capacitor reaches the first threshold value, a control and comparison module is used to compare the capacitor voltage value and the value of an AC power supply signal in a falling interval of each AC cycle, and a first control signal in a pulse form is generated when the difference between the capacitor voltage value and the value of the AC power supply signal is less than or equal to a second threshold value. The first control signal is generated in each cycle, so that a rectifier module performs periodic and step-by-step energy charging on the energy storage capacitor according to the first control signal until the voltage of the energy storage capacitor rises to the peak value of the AC power supply signal, and a second control signal is generated by the control and comparison module. The rectifier module drives the power factor correction circuit according to the second control signal. The present invention performs step-by-step energy charging on the energy storage capacitor in multiple stages to prevent the energy storage capacitor from directly bearing high voltage, thereby protecting the energy storage capacitor.

[0082] The present invention also provides a surge protection method for a power factor correction circuit, comprising the steps of:

[0083] S1, charging the energy storage capacitor preset in the power factor correction circuit with a constant current according to the AC power supply signal, collecting the voltage value of the energy storage capacitor, comparing the voltage value of the energy storage capacitor with a preset first threshold value, and stopping charging the energy storage capacitor when the voltage value of the energy storage capacitor rises to the first threshold value;

[0084] S2. When the voltage value of the energy storage capacitor rises to a first threshold value and the AC power signal is in a falling interval of any cycle, a difference operation is performed on the value of the AC power signal and the voltage value of the energy storage capacitor, and when the difference between the value of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value, a first control signal is generated; the AC power signal is rectified according to the first control signal to obtain a first DC signal, and the energy storage capacitor is charged according to the first DC signal;

[0085] S3. When the energy storage capacitor rises to the peak value of the AC power signal, a second control signal is generated; the AC power signal is rectified according to the second control signal to obtain a second DC signal, and the power factor correction circuit is driven according to the second DC signal.

[0086] The present invention provides a surge protection method for a power factor correction circuit, wherein a constant current charging module is provided to charge an energy storage capacitor so that the voltage of the energy storage capacitor reaches a first threshold value; after the voltage of the energy storage capacitor reaches the first threshold value, a control and comparison module is used to compare the capacitor voltage value and the value of an AC power supply signal in a falling interval of each AC cycle, and a first control signal in a pulse form is generated when the difference between the capacitor voltage value and the value of the AC power supply signal is less than or equal to a second threshold value, and the first control signal is generated in each cycle, so that a rectifier module performs periodic and step-by-step energy charging on the energy storage capacitor according to the first control signal until the voltage of the energy storage capacitor rises to the peak value of the AC power supply signal, and a second control signal is generated by the control and comparison module, and the rectifier module drives the power factor correction circuit according to the second control signal; the present invention performs step-by-step energy charging on the energy storage capacitor through multiple stages to avoid the energy storage capacitor directly bearing high voltage, thereby protecting the energy storage capacitor.

[0087] In the above-mentioned embodiments, although the present invention has been described in conjunction with the specific embodiments of the present invention, many replacements, modifications and variations of these embodiments will be apparent to those of ordinary skill in the art based on the foregoing description. The embodiments of the present invention are intended to cover all such replacements, modifications and variations falling within the broad scope of the appended claims.

[0088] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A surge protection circuit for a power factor correction circuit, characterized in that: Used to provide surge protection for a power correction circuit, wherein an energy storage capacitor is provided at the output end of the power correction circuit, including: A constant current charging module, wherein the input end of the constant current charging module is connected to an external AC power supply, and the output end and the collection end of the constant current charging module are connected to the energy storage capacitor; the constant current charging module is used to perform constant current charging on the energy storage capacitor according to the AC power supply signal, and to collect the voltage value of the energy storage capacitor, and to compare the voltage value of the energy storage capacitor with a preset first threshold value, and when the voltage value of the energy storage capacitor rises to the first threshold value, stop charging the energy storage capacitor; A control and comparison module, wherein a first acquisition terminal of the control and comparison module is connected to an external AC power supply, and a second acquisition terminal of the control and comparison module is connected to the energy storage capacitor; the control and comparison module is used to perform a difference operation on the value of the AC power signal and the voltage value of the energy storage capacitor when the voltage value of the energy storage capacitor rises to a first threshold value and the AC power signal is in a falling interval of any cycle, and generate a first control signal when the difference between the value of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value; the control and comparison module is also used to generate a second control signal when the voltage of the energy storage capacitor rises to a peak value of the AC power signal; A rectifier module, wherein the input end of the rectifier module is connected to an external AC power supply, the output end of the rectifier module is connected to the input end of the power factor correction circuit and the energy storage capacitor, and the control end of the rectifier module is connected to the control and comparison module; the rectifier module is used to rectify the AC power supply signal according to the first control signal to obtain a first DC signal, and charge the energy storage capacitor according to the first DC signal; the rectifier module is also used to rectify the AC power supply signal according to the second control signal to obtain a second DC signal, and drive the power factor correction circuit according to the second DC signal.

2. The surge protection circuit of a power factor correction circuit according to claim 1, characterized in that: The power factor correction circuit has a first input terminal and a second input terminal, and the rectification module includes a first diode, a second diode, a first thyristor and a second thyristor; The anode of the first diode is connected to the first input terminal of the power factor correction circuit, the cathode of the first diode is connected to the anode of the first thyristor, and the cathode of the first thyristor is connected to the second input terminal of the power factor correction circuit; The anode of the second diode is connected to the first input terminal of the power factor correction circuit, the cathode of the second diode is connected to the anode of the second thyristor, and the cathode of the second thyristor is connected to the second input terminal of the power factor correction circuit; The gate of the first thyristor and the gate of the second thyristor are connected to the control and comparison module, one end of the external AC power supply is connected between the cathode of the first diode and the anode of the first thyristor, and the other end of the external AC power supply is connected between the cathode of the second diode and the anode of the second thyristor.

3. The surge protection circuit of a power factor correction circuit according to claim 2, characterized in that: The rectifier module is connected to the energy storage capacitor through a third diode; the anode of the third diode is connected to the cathode of the first thyristor and the cathode of the second thyristor, and the cathode of the third diode is connected to one end of the energy storage capacitor.

4. The surge protection circuit of a power factor correction circuit according to claim 1, characterized in that: The constant current charging module comprises: a first comparing unit, wherein a collecting end of the first comparing unit is connected to the energy storage capacitor, the first comparing unit is used to collect a voltage value of the energy storage capacitor, and to compare the voltage value of the energy storage capacitor with a preset first threshold value, and to generate a stop charging signal when the voltage value of the energy storage capacitor rises to the first threshold value; A constant current charging unit, wherein the input end of the constant current charging unit is connected to an external power supply, the output end of the constant current charging unit is connected to the energy storage capacitor, and the control end of the constant current charging unit is connected to the output end of the comparison unit; the constant current charging unit is used to perform constant current charging on the energy storage capacitor according to an AC power supply signal; the constant current charging unit is also used to stop charging the energy storage capacitor according to the stop charging signal.

5. The surge protection circuit of a power factor correction circuit according to claim 1, characterized in that: The control and comparison modules include: a second comparing unit, wherein a first collecting end of the second comparing unit is connected to an external AC power supply, a second collecting end of the second comparing unit is connected to the energy storage capacitor, and the second comparing unit is used to perform a difference operation on the value of the AC power supply signal and the voltage value of the energy storage capacitor when the voltage value of the energy storage capacitor rises to a first threshold value and the AC power supply signal is in a falling interval of any cycle; A control unit, wherein the control unit is connected to the output end of the second comparison unit, and the control unit is used to generate a first control signal when the difference between the peak value of the current cycle of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value; the control unit is also used to generate a second control signal when the voltage of the energy storage capacitor rises to the peak value of the AC power signal.

6. The surge protection circuit of a power factor correction circuit according to claim 1, characterized in that: The power factor correction circuit has a first output terminal and a second output terminal. One end of the energy storage capacitor is connected to the first output terminal of the power factor correction circuit, and the other end of the energy storage capacitor is connected to the second output terminal of the power factor correction circuit.

7. The surge protection circuit of a power factor correction circuit according to claim 1, characterized in that: The duration of the first control signal is shorter than the period of the AC power signal.

8. A surge protection method for a power factor correction circuit, applied to the surge protection circuit for the power factor correction circuit according to any one of claims 1 to 7, characterized in that: The surge protection method comprises: Performing constant current charging on the energy storage capacitor preset in the power factor correction circuit according to the AC power supply signal, collecting the voltage value of the energy storage capacitor, comparing the voltage value of the energy storage capacitor with a preset first threshold value, and stopping charging the energy storage capacitor when the voltage value of the energy storage capacitor rises to the first threshold value; When the voltage value of the energy storage capacitor rises to a first threshold value and the AC power signal is in a falling interval of any cycle, a difference operation is performed on the value of the AC power signal and the voltage value of the energy storage capacitor, and when the difference between the value of the AC power signal and the voltage value of the energy storage capacitor is less than or equal to a second threshold value, a first control signal is generated; the AC power signal is rectified according to the first control signal to obtain a first DC signal, and the energy storage capacitor is charged according to the first DC signal; When the voltage of the energy storage capacitor rises to the peak value of the AC power signal, a second control signal is generated; the AC power signal is rectified according to the second control signal to obtain a second DC signal, and the power factor correction circuit is driven according to the second DC signal.

Images