Surge current prevention circuit, switching power supply module and surge current prevention method

Abstract

The invention provides an anti-surge current circuit, a switching power supply module and an anti-surge current method, the anti-surge current circuit comprises an electrical parameter detection unit, a driving unit and a switching unit which are connected in sequence, the switching unit is also connected with a power supply and a capacitive load, and the electrical parameter detection unit is also connected with the power supply; the electrical parameter detection unit is used for detecting power supply voltage output by the power supply and outputting the power supply voltage to the driving unit; the driving unit is used for outputting a driving signal to the switch unit when the phase of the power supply voltage is an integral multiple of a half cycle; the switch unit is used for conducting the connection between the power supply and the capacitive load when receiving the driving signal. According to the invention, when the phase of the power supply voltage is the integral multiple of the half cycle, the connection between the power supply and the capacitive load is conducted, so that the switching of the switching power supply is controlled under the condition of no voltage output, and the problem of surge current input is thoroughly solved.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and in particular to a surge current protection circuit, a switching power supply module and a surge current protection method. Background Art

[0002] At the moment the switching power supply is turned on, the power supply voltage output by the switching power supply is rectified and directly charges the filter capacitor or the load including the capacitor. At the moment of starting charging, the internal impedance of the capacitor is very small, which is equivalent to a short circuit. At this time, a large input impact current, namely input surge current, may be generated. The peak value of this surge current can reach hundreds of amperes or even larger. Surge current has a great harm to input fuses, rectification structures, and even filter capacitors and PCB traces.

[0003] In order to solve the harm of input surge current, the industry mainly adopts the method of adding negative temperature coefficient thermistors in the input circuit. When the switching power supply is turned on, due to the presence of negative temperature coefficient thermistors, the surge current is limited when passing through the negative temperature coefficient thermistors, so that the surge current is reduced. Although this method can reduce the surge current, the reliability of this method is low. For example, when the power supply is turned on at high temperature, the resistance of the negative temperature coefficient thermistor is relatively low, and the surge current is still relatively large; and the presence of the negative temperature coefficient thermistor will affect the conversion efficiency of the power supply. In order to solve the problem of power supply conversion efficiency, the industry can also adopt the method of adding thyristors or relays at both ends of the negative temperature coefficient thermistor and adding working timing logic: when the power supply is turned on, the surge current passes through the negative temperature coefficient thermistor, so that the surge current is reduced, and then the thyristors or relays at both ends of the negative temperature coefficient thermistor are closed, the negative temperature coefficient thermistor is short-circuited, and the switching power supply enters a long-term working state; although this solution can improve the conversion efficiency of the power supply, it will introduce additional device costs, and this solution also has low reliability and cannot completely solve the problem of surge current.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The main purpose of the present invention is to provide a surge current protection circuit, a switching power supply module and a surge current protection method, aiming to solve the technical problem that the surge current cannot be completely solved in the prior art.

[0006] To achieve the above object, the present invention provides an inrush current protection circuit, comprising: an electrical parameter detection unit, a drive unit and a switch unit connected in sequence, the switch unit is also connected to a power supply and a capacitive load respectively, and the electrical parameter detection unit is also connected to the power supply;

[0007] The electrical parameter detection unit is used to detect the power supply voltage output by the power supply and output the power supply voltage to the driving unit;

[0008] The driving unit is used to output a driving signal to the switching unit when the phase of the power supply voltage is an integer multiple of half a cycle;

[0009] The switch unit is used to conduct the connection between the power supply and the capacitive load when receiving the driving signal.

[0010] Optionally, the power supply includes: a power neutral line and a power live line, and the switch unit includes: a first sub-switch unit and a second sub-switch unit;

[0011] The first sub-switch unit is arranged in series in a negative voltage power supply circuit composed of the power supply neutral line and the capacitive load, and is used to control the on and off of the negative voltage power supply circuit;

[0012] The second sub-switch unit is arranged in series in a positive voltage power supply circuit composed of the live wire of the power supply and the capacitive load, and is used to control the on and off of the positive voltage power supply circuit.

[0013] Optionally, the driving unit is further configured to output a cutoff signal to the first sub-switch unit and output the driving signal to the second sub-switch unit when the phase of the power supply voltage is an even multiple of a half cycle;

[0014] The driving unit is further configured to output a cutoff signal to the second sub-switch unit and output the driving signal to the first sub-switch unit when the phase of the power supply voltage is an odd multiple of a half cycle.

[0015] Optionally, there is a preset phase difference between the cutoff signal and the driving signal.

[0016] Optionally, the first sub-switch unit includes: a first switch tube; the second sub-switch unit includes: a second switch tube;

[0017] Among them, the control end of the first switch tube and the control end of the second switch tube are both connected to the output end of the driving unit, the input end of the first switch tube and the input end of the second switch tube are both connected to the ground end of the capacitive load, the output end of the first switch tube is connected to the live wire of the power supply, and the output end of the second switch tube is connected to the neutral wire of the power supply.

[0018] Optionally, the surge current protection circuit further includes: a first rectifying diode and a second rectifying diode;

[0019] Wherein, the anode of the first rectifier diode is connected to the power supply neutral line, and the cathode is connected to the input end of the capacitive load;

[0020] The anode of the second rectifier diode is connected to the live wire of the power supply, and the cathode is connected to the input end of the capacitive load.

[0021] In addition, to achieve the above-mentioned purpose, the present invention also provides a switching power supply module, and the switching power supply module includes the above-mentioned surge current protection circuit.

[0022] In addition, to achieve the above-mentioned purpose, the present invention also provides a surge current protection method, which is based on the switching power supply module;

[0023] The surge current protection method comprises:

[0024] Detect the power supply voltage output by the power supply;

[0025] The connection between the power supply and the capacitive load is turned on when the phase of the power supply voltage is an integral multiple of a half cycle.

[0026] Optionally, the step of conducting the connection between the power supply and the capacitive load when the phase of the power supply voltage is an integer multiple of a half cycle includes:

[0027] When the phase of the power supply voltage is an even multiple of a half cycle, disconnecting the negative voltage power supply circuit and connecting the positive voltage power supply circuit;

[0028] When the phase of the power supply voltage is an odd multiple of a half cycle, the positive voltage power supply loop is disconnected and the negative voltage power supply loop is turned on.

[0029] Optionally, when the phase of the power supply voltage is an even multiple of half a cycle, disconnecting the positive voltage power supply circuit and connecting the negative voltage power supply circuit comprises:

[0030] When the phase of the power supply voltage is an even multiple of a half cycle, disconnecting the negative voltage power supply loop;

[0031] Detecting a current phase of the cutoff signal, and turning on a positive voltage power supply circuit when the current phase is a preset phase;

[0032] Correspondingly, when the phase of the power supply voltage is an odd multiple of half a cycle, disconnecting the positive voltage power supply circuit and connecting the negative voltage power supply circuit comprises:

[0033] When the phase of the power supply voltage is an odd multiple of half a cycle, disconnecting the positive voltage power supply loop;

[0034] Detect the current phase of the cut-off signal and turn on the negative voltage power supply circuit when the current phase is the preset phase

[0035] The present invention provides an inrush current protection circuit, a switching power supply module and an inrush current protection method. The inrush current protection circuit includes: an electrical parameter detection unit, a driving unit and a switch unit connected in sequence, the switch unit is also connected to a power supply and a capacitive load respectively, and the electrical parameter detection unit is also connected to the power supply; the electrical parameter detection unit is used to detect the power supply voltage output by the power supply and output the power supply voltage to the driving unit; the driving unit is used to output a driving signal to the switch unit when the phase of the power supply voltage is an integer multiple of half a cycle; the switch unit is used to conduct the connection between the power supply and the capacitive load when receiving the driving signal. In the present invention, by conducting the connection between the power supply and the capacitive load when the phase of the power supply voltage is an integer multiple of half a cycle, the switch of the switching power supply is controlled in the absence of voltage output, and the problem of inrush current input is completely solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0037] Figure 1 A schematic structural diagram of a first embodiment of a surge current protection circuit proposed by the present invention;

[0038] Figure 2 It is a schematic diagram of a surge current protection circuit in the prior art;

[0039] Figure 3 A current curve diagram of a surge current protection circuit in the prior art;

[0040] Figure 4 A schematic structural diagram of a second embodiment of the surge current protection circuit proposed by the present invention;

[0041] Figure 5 A circuit schematic diagram of a switch unit in the surge current protection circuit proposed by the present invention;

[0042] Figure 6 A driving voltage curve diagram of the first switch tube and the second switch tube in the surge current protection circuit proposed by the present invention;

[0043] Figure 7 A schematic diagram of a flow chart of a first embodiment of a surge current protection method provided by the present invention;

[0044] Figure 8It is a flow chart of the second embodiment of the surge current protection method proposed by the present invention.

[0045] Description of Figure Numbers

[0046] Label name Label name 10 Electrical parameter acquisition unit 20 Drive unit 30 Switching unit 301 The first sub-switch unit 302 The second sub-switch unit R Negative Temperature Coefficient Thermistor L Power LiveWire N Power neutral line D1 The first rectifier diode D2 The second rectifier diode Q1 The first switch Q2 The second switch V Supply voltage V1 The first driving voltage V2 The second driving voltage GND Grounding I1 First surge current I2 Second surge current

[0047] 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

[0048] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0051] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] Reference Figure 1 , Figure 1 The present invention provides a first embodiment of a surge current protection circuit.

[0053] like Figure 1 As shown, in this embodiment, the surge current protection circuit includes: an electrical parameter detection unit 10, a drive unit 20 and a switch unit 30 connected in sequence, the switch unit 30 is also connected to the power supply 1 and the capacitive load 2 respectively, and the electrical parameter detection unit 10 is also connected to the power supply 1.

[0054] It should be understood that the input surge current generation mechanism in the switching power supply or the rectifier filter capacitive load is as follows: at the moment the switching power supply is turned on, the capacitive load without stored electrical energy is short-circuited and instantly charged with surge current. Among them, the capacitance of the capacitive load is: Q = i*t (Formula 1); Q = C*U (Formula 2);

[0055] Among them: Q is the amount of electricity, i is the current, t is the time, C is the capacitance, and U is the voltage; from formula 1 and formula 2, we can know that: C is a fixed value in the circuit, t can be considered as a quantitative value when the surge current is generated at the start-up, and U is the change determined by the circuit AC input. When U is a sine 90 degree or 270 degree input, the input voltage peak is the largest, so the corresponding current peak absolute value is the largest; when U is a sine 0 degree or 180 degree input, the input voltage is 0 volts, so the input current is 0 amperes at this time. The value of the surge current is between 0 amperes and this maximum value.

[0056] It is understandable that, referring to Figure 2 In the prior art, a negative temperature coefficient thermistor Rt is set in the voltage output circuit of the switching power supply. When the power is turned on, the surge current is limited when passing through the negative temperature coefficient thermistor Rt due to the presence of the negative temperature coefficient thermistor Rt in the circuit, so that the surge current is reduced. Figure 3 Under normal regulation, the first surge current I1 in the output circuit with the negative temperature coefficient thermistor Rt is significantly smaller than the second surge current I2 in the output circuit without the negative temperature coefficient thermistor Rt. However, at high temperatures, the current limiting effect of the negative temperature coefficient thermistor Rt is significantly reduced, and the surge current will still affect the device. In addition, Figure 3 In the output circuit of the negative temperature coefficient thermistor Rt, there is still a certain surge current. When the voltage value output by the switching unit is large, it may also cause damage to the device, and the problem of surge current cannot be completely solved.

[0057] It should be noted that the electrical parameter detection unit 10 is a structure for detecting parameters such as power supply voltage and current output by the power supply. The electrical parameter detection unit 10 can use specific detection devices such as detection resistors, voltmeters, ammeters, etc., and the specific structure of the electrical parameter detection unit is not limited here. The drive unit 20 is a structure for controlling the specific on-off state of the switch components in the switch unit 30. The drive module 20 can control the on-off or off-off of the switch components in the switch unit 30 by outputting a high level or a low level voltage. The switch unit 30 is a structure arranged between the load and the power supply to control the state of the power supply circuit between the two. The switch unit 30 can be composed of a switch tube and related auxiliary structures, and of course, it can also be composed of a relay and an auxiliary structure.

[0058] In a specific implementation, the electrical parameter detection unit 10 is connected to the power supply 1, and can directly detect the power supply voltage output by the power supply 1, and then output the power supply voltage to the drive unit 20; the drive unit 20 can determine the phase change of the power supply voltage when receiving the power supply voltage, and output a drive signal to the switch unit 30 when the phase of the power supply voltage is an integer multiple of half a cycle of the power supply voltage change; the switch unit 30 can conduct the connection between the power supply and the capacitive load when receiving the drive signal. Among them, the integer multiple of half a cycle can be determined according to the specific voltage output cycle, for example, if the power supply voltage is an AC voltage with a period of 2π, the half cycle is π. At the phase of an integer multiple of half a cycle, the amplitude of the power supply voltage is zero, and at the phase of a quarter cycle, the amplitude of the power supply voltage is the maximum voltage.

[0059] In the first embodiment, the driving unit 20 can use not only the phase of the power supply voltage as a parameter of the output driving signal, but also the amplitude of the power supply voltage as a parameter of the output driving signal. For example, when the driving unit 20 receives the power supply voltage, it determines the voltage amplitude change of the power supply voltage, and when the amplitude of the power supply voltage is at zero voltage, it outputs a driving signal to the switch unit 30 to control the switch power supply to start in the zero voltage state.

[0060] In the present embodiment, a surge current protection circuit is provided, and the surge current protection circuit includes: an electrical parameter detection unit, a driving unit and a switch unit connected in sequence, and the switch unit is also connected to the power supply and the capacitive load respectively, and the electrical parameter detection unit is also connected to the power supply. In the present embodiment, by turning on the connection between the power supply and the capacitive load when the phase of the power supply voltage is an integer multiple of half a cycle, the switch of the switching power supply is controlled in the absence of voltage output, and the problem of surge current input is completely solved. At the same time, since the problem of surge current input can be completely solved, the stability of the switching power supply output circuit can also be improved; in addition, it is not necessary to set a negative temperature coefficient thermistor Rt, which can also greatly improve the conversion efficiency of the power supply, and it is not necessary to set an additional device structure, thereby reducing the cost and volume of the switching power supply output circuit.

[0061] refer to Figure 4 , Figure 4 FIG. 4 is a schematic structural diagram of a second embodiment of a surge current protection circuit according to the present invention.

[0062] like Figure 4 As shown, in this embodiment, the power supply 1 includes: a power neutral line N and a power live line L, and the switch unit 30 includes: a first sub-switch unit 301 and a second sub-switch unit 302;

[0063] The first sub-switch unit 301 is arranged in series in the negative voltage power supply circuit composed of the power supply neutral line N and the capacitive load 2, and is connected to the driving unit 20, and is used to control the on and off of the negative voltage power supply circuit;

[0064] The second sub-switch unit 302 is arranged in series in the positive voltage power supply circuit composed of the power live wire L and the capacitive load 2, and is connected to the driving unit 20 to control the on and off of the positive voltage power supply circuit.

[0065] It can be understood that the power supply 1 is an AC power supply, and the power supply 1 includes a live power line L and a neutral power line N. The number of live power lines L can be one or more, and the number of neutral power lines N can be one. For example, single-phase electricity includes a live power line L and a first neutral power line N, and the input end of the electrical parameter detection unit 10 and the input end of the switch unit 30 can be directly connected to the live power line; while three-phase electricity includes three live power lines L and one neutral power line N. In this case, a live power line L is separately led out to form an output with the neutral power line N. At this time, the input end of the electrical parameter detection unit 10 and the input end of the switch unit 30 need to be connected to a live wire at the same time.

[0066] It should be noted that the second sub-switch unit 302 is a structure for controlling the on-off between the live line L of the power supply and the capacitive load 2. The second sub-switch unit 302 can be set between the live line L of the power supply and the capacitive load 2, or between the capacitive load and the ground terminal, and can control the on-off between the live line L of the power supply and the capacitive load 2. Similarly, the first sub-switch unit 301 is a device for controlling the on-off between the neutral line N of the power supply and the capacitive load 2; the first sub-switch unit 301 can also be set between the neutral line N of the power supply and the capacitive load 2, or between the capacitive load 2 and the ground terminal. Both the first sub-switch unit 301 and the second sub-switch unit 302 are controlled by the driving unit 20. The second sub-switch unit 302 is turned on in the positive half cycle of the power supply voltage, and the first sub-switch unit 301 is turned on in the negative half cycle of the power supply voltage, so that the power supply 1 supplies power to the capacitive load 2 in a complete cycle.

[0067] In a specific implementation process, the driving unit 20 can output a cutoff signal to the first sub-switch unit 301 and output the driving signal to the second sub-switch unit 302 when the phase of the power supply voltage is an even multiple of half a cycle; the first sub-switch unit 301 can disconnect the negative voltage power supply circuit when receiving the cutoff signal; the second sub-switch unit 302 can turn on the positive voltage power supply circuit when receiving the driving signal; when the phase of the power supply voltage is an even multiple of half a cycle, the switching process between the negative voltage power supply circuit and the positive voltage power supply circuit is realized.

[0068] Of course, the driving unit 20 can also output a cutoff signal to the second sub-switch unit 302 and output the driving signal to the first sub-switch unit 301 when the phase of the power supply voltage is an odd multiple of half a cycle; the first sub-switch unit 301 can turn on the negative voltage power supply circuit when receiving the driving signal; the second sub-switch unit 302 can disconnect the positive voltage power supply circuit when receiving the cutoff signal; thereby switching the positive voltage power supply circuit and the negative voltage power supply circuit when the phase of the power supply voltage is an odd multiple of half a cycle.

[0069] Among them, a positive voltage power supply circuit needs to be used to power the capacitive load in the half cycle after the phase that is an even multiple of the half cycle; and a negative voltage power supply circuit needs to be used to power the capacitive load in the half cycle after the phase that is an odd multiple of the half cycle. Therefore, the power supply circuit needs to be switched every half cycle when the phase of the power supply voltage changes.

[0070] In the second embodiment, considering that when the power supply circuit is switched at an integer multiple of a half cycle, two power supply circuits may switch their states at the same time, resulting in both power supply circuits being in the on state at a certain moment, causing power supply abnormality of the switching power supply. Therefore, the driving unit 20 may first output a cutoff signal to a corresponding power supply circuit, and then output a driving signal to the other power supply circuit.

[0071] In a specific implementation, the driving unit 20 may detect the phase of the cutoff signal in real time when outputting the cutoff signal, and after the cutoff signal outputs a certain phase value, the driving unit 20 outputs the driving signal again.

[0072] At this time, there is a phase difference between the cutoff signal and the driving signal, and the phase difference can be a preset phase difference for controlling the interval between the cutoff signal and the driving signal. The preset phase difference can be selected within the dead zone at both ends of the switching phase, for example, a phase difference of 5 degrees is selected before or after the phase of an integer multiple of half a cycle as the preset phase difference.

[0073] Reference Figure 5 In this embodiment, the first sub-switch unit 301 includes: a first switch tube Q1; the second sub-switch unit 302 includes: a second switch tube Q2;

[0074] Among them, the control end of the first switch tube Q1 and the control end of the second switch tube Q2 are both connected to the output end of the driving unit 20, the input end of the first switch tube Q1 and the input end of the second switch tube Q2 are both connected to the ground end of the capacitive load 2, the output end of the first switch tube Q1 is connected to the live wire L of the power supply, and the output end of the second switch tube N is connected to the neutral wire N of the power supply.

[0075] exist Figure 5 In the embodiment, a switch tube is used as a specific on-off control device, and the switch tube can be a switch device with a control end, such as a MOS tube, a thyristor, an IGBT, a magnetic switch, etc. The control end of the first switch tube Q1 is connected to the first output end of the drive unit 20, and the control end of the second switch tube Q2 is connected to the second output end of the drive unit 20.

[0076] Reference Figure 6 ,exist Figure 6 The power supply voltage V, the first driving voltage V1 of the first switch tube Q1, and the second driving voltage of the second switch tube Q2 are shown in FIG. The specific control logic of the first switch tube Q1 and the second switch tube Q2 is that the driving unit 20 outputs a cut-off signal to the second switch tube Q2 to control the second switch tube Q2 to be cut off when the phase of the power supply voltage is 180 degrees, and after a preset phase interval, outputs the driving signal to the first switch tube Q1 to control the first switch tube Q1 to turn on the negative voltage power supply circuit; of course, when the phase of the power supply voltage is 0 degrees, the driving unit 20 outputs a cut-off signal to the first switch tube Q1 to control the first switch tube Q1 to be cut off, and then after a preset phase interval, outputs the driving signal to the second switch tube Q2 to control the second switch tube Q2 to turn on the positive voltage power supply circuit. Among them, the first switch tube Q1 and the second switch tube Q2 are turned on alternately.

[0077] In addition, the surge current protection circuit further includes: a first rectifier diode D1 and a second rectifier diode D2;

[0078] Wherein, the anode of the first rectifier diode D1 is connected to the power supply neutral line N, and the cathode is connected to the input end of the capacitive load 2;

[0079] The anode of the second rectifier diode D2 is connected to the live wire L of the power supply, and the cathode is connected to the input end of the capacitive load 2 .

[0080] It should be understood that when the power supply 1 outputs the power supply voltage, the power supply voltage is an AC voltage, and the AC voltage will be directly grounded through the capacitor C in the capacitive load 2. Therefore, it is necessary to convert the power supply voltage into a DC voltage, and then use the DC voltage to power the capacitor C in the capacitive load 2.

[0081] In the second embodiment, a rectifier diode is used to rectify the power supply voltage. The first rectifier diode D1 is arranged in the negative voltage power supply circuit, and can rectify the power supply voltage in the negative half cycle, and then when the first switch tube Q1 is turned on, the rectified power supply voltage is used to supply power to the capacitive load 2; similarly, the second rectifier diode D2 can rectify the power supply voltage in the positive half cycle, and then when the second switch tube Q2 is turned on, the rectified power supply voltage is used to supply power to the capacitive load 2.

[0082] In the first half cycle of the power output, for example, 0-180 degrees, the second switch tube Q2 is turned on, and the current in the power supply circuit flows from the second rectifier diode D2 to the capacitive load 2 and then to the second switch tube Q2, and flows back to the current live wire L; in the second half cycle of the power output, for example, 180-360 degrees, the first switch tube Q1 is turned on, and the current in the power supply circuit flows from the first rectifier diode D1 to the capacitive load and then to the first switch tube Q1, and flows back to the power neutral line N.

[0083] In addition, an embodiment of the present invention further provides a switching power supply module, which includes the surge current protection circuit described in the above embodiments. The switching power supply module can also have the function of the surge current protection circuit.

[0084] In addition, to achieve the above-mentioned purpose, the present invention also proposes a surge current protection method, which is implemented based on the switching power supply module.

[0085] Reference Figure 7 , Figure 7 It is a flow chart of the first embodiment of the surge current protection method proposed by the present invention.

[0086] Reference Figure 7 In this embodiment, the surge current protection method includes:

[0087] Step S10: Detecting the power supply voltage output by the power supply;

[0088] Step S20: When the phase of the power supply voltage is an integer multiple of half a cycle, the connection between the power supply and the capacitive load is turned on.

[0089] It can be understood that the execution subject can be the switching power supply module in the above embodiment or the driving unit in the switching power supply module. The specific structure of the switching power supply module can refer to the above embodiment and is not specifically limited here. In this embodiment, the switching unit module is taken as the execution subject for explanation.

[0090] It should be understood that the integer multiple of the half cycle can be determined according to the specific voltage output cycle. At the phase of the integer multiple of the half cycle, the amplitude of the power supply voltage is zero, and at this time, the connection between the power supply and the capacitive load is turned on, and there will be no surge current.

[0091] In a specific implementation, an electrical parameter detection unit in a switching power supply module can be used to directly detect the power supply voltage of the power supply 1, and then the power supply voltage is sent to a driving unit in the switching power supply module; the driving unit can detect the phase change of the power supply voltage when receiving the power supply voltage, and when the phase of the power supply voltage is an integer multiple of half a cycle of the power supply voltage change, output a driving signal to control the switching unit to turn on the connection between the power supply and the capacitive load.

[0092] A surge current protection method is provided in this embodiment. The method switches on the power supply and the capacitive load when the phase of the power supply voltage is an integer multiple of half a cycle, thereby controlling the switching power supply switch in the absence of voltage output, thereby completely solving the surge current input problem.

[0093] In addition, this method can completely solve the problem of surge current input and improve the stability of the switching power supply output circuit; this method does not require the setting of a negative temperature coefficient thermistor, and can also greatly improve the conversion efficiency of the power supply and reduce the cost and volume of the switching power supply output circuit.

[0094] Based on the first embodiment of the surge current protection method described above, a second embodiment of the surge current protection method of the present invention is proposed.

[0095] In the second embodiment, the step S20 specifically includes:

[0096] Reference Figure 8 When the phase of the power supply voltage is an even multiple of a half cycle, the negative voltage power supply circuit is disconnected and the positive voltage power supply circuit is turned on; when the phase of the power supply voltage is an odd multiple of a half cycle, the negative voltage power supply circuit is turned on and the positive voltage power supply circuit is disconnected. When the phase of the power supply voltage is in the first half cycle, the positive voltage power supply circuit can be kept turned on and the negative voltage power supply circuit can be turned off; when the phase of the power supply voltage is in the second half cycle, the negative voltage power supply circuit can be kept turned on and the positive voltage power supply circuit can be turned off.

[0097] Considering that when the power supply circuit is switched, two power supply circuits may be switched at the same time, causing both power supply circuits to be in the on state at a certain moment, resulting in power supply abnormality of the switching power supply. In order to avoid power supply abnormality, the on-off control process of the power supply circuit also includes:

[0098] When the phase of the power supply voltage is an even multiple of a half cycle, the negative voltage power supply loop is disconnected first, then the current phase of the cutoff signal is detected, and when the current phase is a preset phase, the positive voltage power supply loop is turned on.

[0099] Alternatively, when the phase of the power supply voltage is an odd multiple of a half cycle, the positive voltage power supply circuit is disconnected first; then, the current phase of the cutoff signal is detected, and when the current phase is a preset phase, the negative voltage power supply circuit is turned on.

[0100] Among them, the current phase is the phase value of the cutoff signal at the current moment, and the phase value of the current phase will change with time. The preset phase is a pre-set phase used to control a certain phase difference between the cutoff signal and the drive signal. When the cutoff signal is in the preset phase, the drive signal starts to be output, which can ensure that there is a preset phase difference between the cutoff signal and the drive signal, thereby avoiding power supply anomalies caused by the simultaneous conduction of two power supply circuits.

[0101] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

[0102] It is worth noting that in the actual application of the present invention, software programs will inevitably be applied, but the applicant hereby declares that the software programs used in the specific implementation of the technical solution are all prior art. In this application, it does not involve the modification and protection of software programs, but only the protection of the hardware architecture designed to achieve the purpose of the invention.

Claims

1. A surge current protection circuit, characterized in that: The surge current protection circuit comprises: an electrical parameter detection unit, a driving unit and a switch unit connected in sequence, the switch unit is also connected to a power supply and a capacitive load respectively, and the electrical parameter detection unit is also connected to the power supply; The electrical parameter detection unit is used to detect the power supply voltage output by the power supply and output the power supply voltage to the driving unit; The driving unit is used to output a driving signal to the switching unit when the phase of the power supply voltage is an integer multiple of half a cycle; The switch unit is used to conduct the connection between the power supply and the capacitive load when receiving the driving signal.

2. The surge current protection circuit according to claim 1, characterized in that: The power supply includes: a power neutral line and a power live line, and the switch unit includes: a first sub-switch unit and a second sub-switch unit; The first sub-switch unit is arranged in series in a negative voltage power supply circuit composed of the power supply neutral line and the capacitive load, and is connected to the driving unit, and is used to control the on and off of the negative voltage power supply circuit; The second sub-switch unit is arranged in series in a positive voltage power supply circuit composed of the live wire of the power supply and the capacitive load, and is connected to the driving unit to control the on and off of the positive voltage power supply circuit.

3. The surge current protection circuit according to claim 2, characterized in that: The driving unit is further configured to output a cutoff signal to the first sub-switch unit and output the driving signal to the second sub-switch unit when the phase of the power supply voltage is an even multiple of a half cycle; The driving unit is further configured to output a cutoff signal to the second sub-switch unit and output the driving signal to the first sub-switch unit when the phase of the power supply voltage is an odd multiple of a half cycle.

4. The surge current protection circuit according to claim 3, characterized in that: There is a preset phase difference between the cutoff signal and the driving signal.

5. The surge current protection circuit according to claim 2, characterized in that: The first sub-switch unit includes: a first switch tube; the second sub-switch unit includes: a second switch tube; Among them, the control end of the first switch tube and the control end of the second switch tube are both connected to the output end of the driving unit, the input end of the first switch tube and the input end of the second switch tube are both connected to the ground end of the capacitive load, the output end of the first switch tube is connected to the live wire of the power supply, and the output end of the second switch tube is connected to the neutral wire of the power supply.

6. The surge current protection circuit according to claim 5, characterized in that: The surge current protection circuit further includes: a first rectifying diode and a second rectifying diode; Wherein, the anode of the first rectifier diode is connected to the power supply neutral line, and the cathode is connected to the input end of the capacitive load; The anode of the second rectifier diode is connected to the live wire of the power supply, and the cathode is connected to the input end of the capacitive load.

7. A switching power supply module, characterized in that: The switching power supply module includes the surge current protection circuit described in any one of claims 1-6.

8. A method for preventing surge current, characterized in that: The surge current protection method is based on the switching power supply module according to claim 7; The surge current protection method comprises: Detect the power supply voltage output by the power supply; The connection between the power supply and the capacitive load is turned on when the phase of the power supply voltage is an integral multiple of a half cycle.

9. The surge current protection method according to claim 8, characterized in that: The step of conducting the connection between the power supply and the capacitive load when the phase of the power supply voltage is an integer multiple of a half cycle comprises: When the phase of the power supply voltage is an even multiple of a half cycle, disconnecting the negative voltage power supply circuit and connecting the positive voltage power supply circuit; When the phase of the power supply voltage is an odd multiple of a half cycle, the positive voltage power supply loop is disconnected and the negative voltage power supply loop is turned on.

10. The surge current protection method according to claim 9, characterized in that: When the phase of the power supply voltage is an even multiple of half a cycle, the positive voltage power supply circuit is disconnected and the negative voltage power supply circuit is turned on: comprising When the phase of the power supply voltage is an even multiple of a half cycle, disconnecting the negative voltage power supply loop; Detecting a current phase of the cutoff signal, and turning on a positive voltage power supply circuit when the current phase is a preset phase; Correspondingly, when the phase of the power supply voltage is an odd multiple of half a cycle, disconnecting the positive voltage power supply circuit and connecting the negative voltage power supply circuit comprises: When the phase of the power supply voltage is an odd multiple of a half cycle, disconnecting the positive voltage power supply loop; The current phase of the cut-off signal is detected, and when the current phase is a preset phase, the negative voltage power supply loop is turned on.

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