Converter and switched mode power supply

Abstract

The application provides a converter and a switching mode power supply, the converter comprising a rectifier circuit, a filter circuit, a voltage detection circuit, a control unit and a current conversion circuit, the filter circuit comprising a filter capacitor; an alternating current is connected to the input end of the rectifier circuit, the output end of the rectifier circuit is connected to the filter circuit, the filter circuit is connected to the current conversion circuit, the voltage detection circuit detects the output voltage between the two ends of the rectifier circuit, the control unit is connected to the voltage detection circuit and the filter circuit respectively, the control unit controls the on-off of the filter circuit according to the detection voltage of the voltage detection circuit, and the filter circuit is turned off when the voltage input into the filter circuit is too high; the voltage resistance of the converter is improved without changing the original filter capacitor of the converter, and then the size of the switching mode power supply using the converter is reduced, and the cost of the switching mode power supply is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a converter and a switching mode power supply. BACKGROUND

[0002] The switching mode power supply as a kind of power supply is widely used in charger circuit of mobile phone and digital camera, and the switching mode power supply includes a converter, which is converted into DC output after rectification and filtering of AC input.

[0003] However, in unstable power grid areas, it is easy to cause damage to the switching mode power supply, especially to the filter capacitor for rectification and filtering. In order to solve the above problems, the prior art usually uses high-voltage electrolytic capacitor for filtering, or uses a scheme of two capacitors in series to improve the high-voltage resistance.

[0004] However, the use of high-voltage electrolytic capacitor for filtering has high cost, and the use of two capacitors in series has large size and high cost. SUMMARY

[0005] The present application provides a converter and a switching mode power supply, which solves the problems of large size and high cost of the prior art switching mode power supply.

[0006] In a first aspect, the present application provides a converter, comprising:

[0007] a rectifier circuit, a filter circuit, a voltage detection circuit, a control unit and a current conversion circuit, the filter circuit comprising a filter capacitor;

[0008] The input end of the rectifier circuit is externally connected to AC power, the output end of the rectifier circuit is connected to the filter circuit, the filter circuit is connected to the current conversion circuit, the voltage detection circuit detects the output voltage across the rectifier circuit, the voltage detection circuit is connected to the control unit, the control unit is connected to the voltage detection circuit and the filter circuit respectively, and the control unit controls the on-off of the filter circuit according to the detection voltage of the voltage detection circuit.

[0009] The voltage detection circuit can detect the output voltage across the rectifier circuit, i.e. the voltage across the input filter circuit, and the control unit can control the on-off of the filter circuit based on the detection voltage of the voltage detection circuit, which can disconnect the filter circuit when the voltage across the input filter circuit is too high, thereby reducing the damage to the filter capacitor in the circuit, improving the voltage resistance of the converter without changing the original filter capacitor of the converter, and further reducing the size of the switching mode power supply using the converter and reducing the cost of the switching mode power supply.

[0010] Optionally, the control unit is further connected to the current conversion circuit, and the control unit controls the on-off of the current conversion circuit according to the detection voltage; the voltage detection circuit can detect the output voltage between the rectifier circuit, that is, the voltage between the input filter circuit and the voltage between the input current conversion circuit; the control unit can control the on-off of the filter circuit and the current conversion circuit through the voltage detection circuit; when the voltage of the input filter circuit is too high, the filter circuit and the current conversion circuit are disconnected, which reduces the damage of the filter capacitor and the current conversion circuit in the circuit, further prolongs the service life of the converter, and because the application uses a capacitor with low voltage resistance, a product with high voltage resistance can be realized, the volume and cost of the voltage capacitor are low, the product volume can be reduced, and the cost of the converter is also reduced.

[0011] Optionally, the electronic switch is further connected in series with the filter circuit; the control unit is connected to the electronic switch, and the control unit controls the on-off of the electronic switch according to the detection voltage; the control unit controls the on-off of the filter circuit through the electronic switch, thereby improving the accuracy of the control of the converter.

[0012] Optionally, the control unit controls the on-off of the filter circuit according to the detection voltage of the voltage detection circuit, and the method comprises: the control unit determines whether the detection voltage is higher than a first preset threshold; if the detection voltage is higher than the first preset threshold, the control unit controls the filter circuit to be disconnected.

[0013] Optionally, the control unit controls the on-off of the filter circuit according to the detection voltage of the voltage detection circuit, and the method further comprises: the control unit determines whether the detection voltage is lower than a second preset threshold, and the first preset threshold is greater than the second preset threshold; if the detection voltage is lower than the second preset threshold, the control unit controls the filter circuit to be connected.

[0014] When the detection voltage of the detection circuit is too high, the filter circuit is disconnected to prevent damage caused by the high voltage to the filter circuit; when the detection voltage of the detection circuit is lower than a preset threshold, the filter circuit is disconnected to ensure the normal operation of the converter, further improve the voltage resistance of the converter, and reduce the cost.

[0015] Optionally, the rectifier circuit comprises a first diode, a second diode, a third diode and a fourth diode; the first diode and the second diode are connected in series, the third diode and the fourth diode are connected in series, the positive electrode of the first diode is connected to the positive electrode of the third diode, and one end of the filter circuit is connected; the negative electrode of the second diode is connected to the negative electrode of the fourth diode, and the other end of the filter circuit is connected. Here, four diodes are used to form the rectifier circuit, so that the rectification effect of the rectifier circuit is better, and the rectification effect of the converter is further improved.

[0016] Optionally, the voltage detection circuit comprises a first resistor and a second resistor; one end of the first resistor is connected to one end of the rectifier circuit, the other end of the first resistor is connected to one end of the second resistor and the control unit respectively, and the other end of the second resistor is connected to the other end of the rectifier circuit. Here, the voltage of the converter circuit is detected by the voltage division of the two resistors, which is simple in structure and low in component cost, further reducing the cost.

[0017] Optionally, the electronic switch is a field effect transistor, a thyristor, a bipolar junction transistor or an insulated gate bipolar transistor.

[0018] Optionally, the converter further comprises a third resistor.

[0019] One end of the third resistor is connected to the power supply, and the other end of the third resistor is connected to the control unit. The power supply supplies power to the control unit through the third resistor. Wherein, the power supply is supplied by the power supply of the converter itself, further saving resources and reducing costs.

[0020] Optionally, the converter is an AC-DC converter, and the control unit is further connected to a current conversion circuit, and the current conversion circuit supplies power to the control unit, further saving resources and reducing costs.

[0021] Optionally, the control unit controls the filter circuit to be disconnected when the detection voltage of the voltage detection circuit reaches a preset threshold, that is, when the detection voltage of the detection circuit is too high, the filter circuit is disconnected to prevent damage to the filter circuit caused by the voltage being too high, further improving the voltage resistance of the converter and reducing the cost.

[0022] Optionally, the current conversion circuit is a DC-DC converter.

[0023] In a second aspect, the application provides a converter control method, comprising: obtaining a detection voltage of a voltage detection circuit, wherein the voltage detection circuit detects an output voltage across the rectifier circuit, the input end of the rectifier circuit is externally connected to an alternating current, and the output end of the rectifier circuit is connected to a filter circuit; controlling the on-off of the filter circuit according to the detection voltage, wherein the filter circuit comprises a filter capacitor, and the filter circuit is connected to a current conversion circuit.

[0024] Optionally, it further comprises: controlling the on-off of the current conversion circuit according to the detection voltage.

[0025] Optionally, controlling the on-off of the filter circuit according to the detection voltage comprises: determining whether the detection voltage is higher than a first preset threshold; if the detection voltage is higher than the first preset threshold, controlling the filter circuit to be disconnected.

[0026] In a third aspect, the application provides a switching mode power supply, comprising a converter as described in the first aspect or the optional manner of the first aspect.

[0027] The converter and the switching mode power supply provided by the embodiments of the present application, wherein the converter detects the output voltage across the rectifier circuit, i.e. the voltage across the input filter circuit, by the voltage detection circuit, so that the control unit controls the on-off of the filter circuit based on the detection voltage of the voltage detection circuit, and the filter circuit can be turned off when the voltage across the input filter circuit is too high, thereby reducing the damage of the filter capacitor in the circuit, improving the voltage resistance of the converter without changing the original filter capacitor of the converter, and further reducing the size of the switching mode power supply using the above converter, and the product can bear high voltage by using the capacitor with low voltage resistance, and the voltage capacitor is low in size and cost, thereby reducing the size of the product and the cost of the switching mode power supply. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0030] Figure 1 A circuit schematic diagram of a converter provided by an embodiment of the present application;

[0031] Figure 2 Another circuit schematic diagram of a converter provided by an embodiment of the present application;

[0032] Figure 3 Another circuit schematic diagram of a converter provided by an embodiment of the present application;

[0033] Figure 4 Another circuit schematic diagram of a converter provided by an embodiment of the present application;

[0034] Figure 5 Another circuit schematic diagram of a converter provided by an embodiment of the present application;

[0035] Figure 6 Another circuit schematic diagram of a converter provided by an embodiment of the present application;

[0036] Figure 7 Another circuit schematic diagram of a converter provided by an embodiment of the present application;

[0037] Figure 8A circuit schematic of yet another converter is provided for an embodiment of the present application.

[0038] The specific embodiments of the present disclosure have been shown by the above-described drawings, and will be described in more detail hereinafter. The drawings and the written description are not intended to restrict the scope of the present disclosure concept in any way, but to illustrate the present disclosure concept to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0039] In order to make the purposes, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings of the preferred embodiments of the present application. In the drawings, the same or similar notations represent the same or similar components or components having the same or similar functions throughout. The described embodiments are some of the embodiments of the present application, not all of the embodiments. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0040] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be a fixed connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] Switching mode power supply is widely used in chargers of electronic products such as mobile phones and digital cameras, which can convert the alternating current input during charging into direct current required during operation of electronic products. However, the switching mode power supply with general 100V-265V alternating current input often uses high-voltage electrolytic capacitor with withstand voltage of 400V as filter capacitor. When the input voltage is too high, the voltage on the filter capacitor is too high, which can easily cause the filter capacitor to burn out, resulting in damage to the entire current. The prior art usually increases the withstand voltage of the filter capacitor to 550V. However, the cost of high-voltage electrolytic capacitor is relatively high. Another solution is to use two capacitors in series, or to use two capacitors in series. However, the cost of using high-voltage electrolytic capacitor as filter is relatively high, and the volume of using two capacitors in series is relatively large, and the cost is also relatively high.

[0042] To solve the above problems, the embodiment of the present application provides a converter which can be applied to a switch mode power supply and other AC-DC conversion circuits, the converter comprises a voltage detection circuit for detecting the voltage of an input filter circuit, and a control unit for controlling the on-off of the filter circuit, thereby preventing the damage of a filter capacitor in the filter circuit caused by the excessively high voltage and reducing the size and cost of the converter.

[0043] The converter provided by the present application will be described in detail in combination with specific embodiments.

[0044] Figure 1 The circuit schematic diagram of the converter provided by the embodiment of the present application is shown in the figure. Figure 1 As shown in the figure, the converter of the embodiment of the present application comprises a rectifier circuit 31, a filter circuit 32, a voltage detection circuit 33, a control unit 34 and a current conversion circuit 35, and the filter circuit 32 comprises a filter capacitor 320.

[0045] The input end of the rectifier circuit 31 is connected with an AC power supply, the output end of the rectifier circuit 31 is connected with the filter circuit 32, the filter circuit 32 is connected with the current conversion circuit 35, the voltage detection circuit 33 detects the output voltage between the two ends of the rectifier circuit 31, the control unit 34 is connected with the voltage detection circuit 33 and the filter circuit 32 respectively, and the control unit 34 controls the on-off of the filter circuit 32 according to the detected voltage of the voltage detection circuit 33.

[0046] The function of the rectifier circuit 31 is to convert the input AC power into unidirectional pulsating DC power. The voltage after the rectifier circuit is not an AC voltage, but a mixed voltage containing DC voltage and AC voltage. The function of the filter circuit 32 is to reduce the AC component in the DC voltage as much as possible, retain the DC component, reduce the output voltage ripple coefficient and make the waveform smoother. In the embodiment, the AC input is converted into a mixed voltage of high-voltage DC power and a small amount of AC power after passing through the rectifier circuit 31, and then the AC voltage is filtered out by the filter circuit 32. The voltage detection circuit 33 detects the output voltage between the two ends of the rectifier circuit 31. If the output voltage between the two ends of the rectifier circuit 31 is too high, the voltage detection circuit 33 will feed back the signal to the control unit 34, and the control unit 34 can control the filter circuit 32 to be disconnected, thereby preventing the damage of the filter capacitor 302 caused by the excessively high voltage input to the filter circuit 32. Optionally, the rectifier circuit 31 can be a half-wave rectifier circuit, a full-wave rectifier circuit or a bridge rectifier circuit. The rectifier circuit 31 can be composed of only uncontrollable diodes, or composed of a mixture of controllable elements and diodes, or composed of all controllable elements. The present application does not make specific limitation in this regard.

[0047] Optionally, the voltage detection circuit 33 can detect through a voltage dividing resistor, through a voltage transformer, or through a voltage stabilizing chip, and the application does not make specific limitation on this.

[0048] Optionally, when the voltage detected by the voltage detection circuit 33 reaches the first preset threshold, the control unit 34 controls the filter circuit 32 to be disconnected, and when the voltage detected by the detection circuit is too high, the filter circuit 32 is disconnected to prevent damage to the filter circuit 32 caused by the voltage being too high.

[0049] Optionally, when the voltage detected by the voltage detection circuit 33 is lower than the second preset threshold, the control unit 34 controls the filter circuit 32 to be connected to ensure the normal operation of the converter. The second preset threshold is lower than the first preset threshold.

[0050] Optionally, the first preset threshold can be the rated voltage of the filter capacitor 320, or a voltage value lower than the preset threshold of the rated voltage of the filter capacitor 320.

[0051] Optionally, the current conversion circuit 35 is a direct current-direct current conversion circuit.

[0052] In the embodiment, the voltage detection circuit is added to detect the output voltage of the rectifier circuit, i.e. the voltage input to the filter circuit, and the control unit can control the connection and disconnection of the filter circuit according to the voltage detected by the voltage detection circuit, thereby preventing damage to the filter voltage caused by the voltage being too high. The voltage resistance of the converter is improved without changing the original filter capacitor of the converter, the size of the converter is reduced, and the product can withstand high voltage by using a capacitor with low voltage resistance, the size and cost of the voltage capacitor are low, the size of the product can be reduced, and the cost of the converter is also reduced.

[0053] Figure 2 Another circuit schematic diagram of a converter provided by an embodiment of the application is shown in FIG. 3. Figure 2 As shown in FIG. 3, Figure 2 on the basis of Figure 1 further,

[0054] The control unit 34 is also connected to the current conversion circuit 35, and the control unit 34 controls the connection and disconnection of the current conversion circuit 35 according to the detected voltage. The voltage detection circuit 33 can detect the output voltage between the two ends of the rectifier circuit 31.

[0055] The current conversion circuit 35 is an electric energy conversion circuit or an electromechanical device, which can convert a direct current power supply into a direct current power supply with different voltage. In the application, a high-voltage direct current is converted into a low-voltage direct current. The current conversion circuit 35 in the application can be an electronic conversion circuit, an electromechanical conversion circuit, and an electrochemical conversion circuit, and the application does not make specific limitation on this.

[0056] Optionally, the current conversion circuit 35 can be an electronic conversion circuit composed of an integrated circuit plus several parts, or a complete hybrid integrated circuit module that only needs to be assembled on a circuit board, and the present application does not make specific limitations on this.

[0057] In order to better protect the current conversion circuit 35, the control unit 34 connected with the voltage detection module 33 is further used to control the on-off of the current conversion circuit 35, and when the voltage detection module 33 detects that the output voltage of the rectifier circuit 31, i.e. the output voltage of the current conversion circuit 35, is too high, the control unit 34 controls to turn off the current conversion circuit 35.

[0058] Optionally, the control unit 34 controls the current conversion circuit 35 to turn off when the detection voltage of the voltage detection circuit 33 is higher than a third preset threshold, and the current conversion circuit 35 is turned off when the detection voltage of the detection circuit is too high, so as to prevent damage to the current conversion circuit 35 caused by the voltage being too high.

[0059] Optionally, the control unit 34 controls the current conversion circuit 35 to turn on when the detection voltage of the voltage detection circuit 33 is lower than a fourth preset threshold, and the current conversion circuit 35 is turned on when the detection voltage of the detection circuit is lower than the fourth preset threshold, so as to ensure the normal operation of the converter. The fourth preset threshold is lower than the third preset threshold.

[0060] Optionally, the third preset threshold can be the rated voltage of the current conversion circuit 35, or a voltage value lower than the preset threshold of the rated voltage of the current conversion circuit 35. The rated voltage is the minimum value of the rated voltage of the current conversion circuit 35 when the internal elements of the current conversion circuit 35 reach the rated voltage.

[0061] The control unit of the present embodiment not only controls the filter circuit, but also controls the current conversion circuit according to the detection voltage, so as to prevent damage to the current conversion circuit caused by overvoltage of the circuit, further prolong the service life of the converter, and reduce the cost.

[0062] Figure 3 Another circuit schematic diagram of a converter provided by an embodiment of the present application is shown in FIG. 4. Figure 3 As shown in FIG. 4, Figure 3 on the basis of the embodiment shown in FIG. 3, Figure 1 further,

[0063] the electronic switch 321 is further included, and the filter circuit 32 and the electronic switch 321 are connected in series; the control unit 34 is connected with the electronic switch 321, and the control unit 34 controls the on-off of the electronic switch 321 according to the detection current.

[0064] Optionally, the electronic switch 321 can be a thyristor, a transistor, a field effect transistor, a silicon controlled rectifier, a relay, a bipolar junction transistor or an insulated gate bipolar transistor, etc., which is not specifically limited in the present application.

[0065] Optionally, Figure 4 The present application provides another circuit schematic diagram of a transformer, Figure 4 on the basis of the embodiment shown in Figure 2 and Figure 3 Further, as shown in Figure 4 , the current conversion circuit 35 further comprises an electronic switch 351, and the control unit 34 is connected to the electronic switch 321, and the control unit 34 controls the on-off of the electronic switch 351.

[0066] The electronic switch refers to an operating unit for realizing the on-off of the circuit by using an electronic circuit and a power electronic device, at least comprising a controllable electronic driving device, having the characteristics of small size, high reliability, anti-interference and low cost, in the present embodiment, the electronic switch is used to control the on-off of the circuit, further reducing the size of the transformer, reducing the cost and improving the accuracy of controlling the transformer.

[0067] Figure 5 The present application provides another circuit schematic diagram of a transformer, Figure 5 on the basis of the embodiment shown in Figure 1 Further,

[0068] The rectifier circuit 31 comprises a first diode 311, a second diode 312, a third diode 313 and a fourth diode 314; the first diode 311 and the second diode 312 are connected in series, the third diode 313 and the fourth diode 314 are connected in series, the positive electrode of the first diode 311 is connected to the positive electrode of the third diode 313, and then connected to one end of the filter circuit, and the negative electrode of the second diode 312 is connected to the negative electrode of the fourth diode 314, and then connected to the other end of the filter circuit.

[0069] Optionally, the diode can be a fast recovery diode, a super-fast recovery diode and a Schottky diode, etc., which is not specifically limited in the present application.

[0070] The first diode 311, the second diode 312, the third diode 313 and the fourth diode 314 form a rectifier bridge, i.e. the rectifier circuit 31. Exemplarily, the input of the rectifier circuit 31 is a sine alternating current containing positive and negative periods. When the input voltage is in the positive half period, the first diode 311 and the third diode 313 are applied with a forward voltage, and the first diode 311 and the third diode 313 are turned on; the second diode 312 and the fourth diode 314 are applied with a reverse voltage, and the second diode 312 and the fourth diode 314 are turned off. The input voltage, the first diode 311, the third diode 313 and the subsequent circuit form a power circuit, and a half-wave rectified voltage with a positive upper and a negative lower is formed. When the input voltage is in the negative half period, the second diode 312 and the fourth diode 314 are applied with a forward voltage, and the second diode 312 and the fourth diode 314 are turned on; the first diode 311 and the third diode 313 are applied with a reverse voltage, and the first diode 311 and the third diode 313 are turned off. The input voltage, the second diode 312, the fourth diode 314 and the subsequent circuit form a power circuit, and another half-wave rectified voltage with a positive upper and a negative lower is formed. The process is repeated, and a full-wave rectified voltage is obtained, and the rectification of alternating current to direct current is realized.

[0071] The four diodes in the embodiment form a rectifier circuit, and a full-wave rectifier circuit is formed. The rectification effect is just right, the efficiency is higher, the resources are saved, the rectification effect of the converter is further improved, and the cost is reduced.

[0072] Figure 6 Another circuit schematic diagram of a converter is provided in the embodiment of the present application, Figure 6 is Figure 1 based on the embodiment shown in the embodiment, further,

[0073] The voltage detection circuit 33 includes a first resistor 331 and a second resistor 332. One end of the first resistor 331 is connected to one end of the rectifier circuit 31, and the other end of the first resistor 331 is connected to one end of the second resistor 332 and the control unit 34, respectively. The other end of the second resistor 332 is connected to the other end of the rectifier circuit 31.

[0074] It can be understood that the parameters and materials of the first resistor 331 and the second resistor 332 are not specifically limited in the present application. In order to save cost, a resistor with good stability and low power can be selected.

[0075] The series circuit resistance divides the voltage, and the voltage detection can be realized by the voltage division of the first resistor 331 and the second resistor 332. According to the percentage of the voltage division of each resistor in the total resistance, the voltage detection value can be obtained by simple calculation. The voltage detection circuit is composed of two simple resistors in series, and the implementation and structure are simple. Further, the size of the converter is reduced, and the cost of the converter is saved.

[0076] Figure 7 Fig. 3 is a circuit schematic diagram of another transformer according to an embodiment of the present application, Figure 7 is based on Figure 1 Further, based on the embodiment shown in Fig. 3, the transformer further comprises:

[0077] a third resistor 37, one end of the third resistor 37 is connected to the power supply, and the other end of the third resistor 37 is connected to the control unit 34, and the power supply supplies power to the control unit 34 through the third resistor 37.

[0078] The control unit can be connected to the power supply of the transformer through the third resistor 37, so that the transformer itself can supply power to the control unit 34, thereby saving the cost of the transformer.

[0079] Optionally, the control unit 34 is further connected to the current conversion circuit 35, and the current conversion circuit 35 supplies power to the control unit 34.

[0080] As shown in Figure 8 , Figure 8 Fig. 4 is a circuit schematic diagram of another transformer according to an embodiment of the present application, by connecting the control unit to the current conversion circuit 35 of the transformer, so that the current conversion circuit of the transformer can supply power to the control unit 34, thereby saving the cost of the transformer.

[0081] The embodiment of the present application further provides a transformer control method, comprising:

[0082] obtaining a detection voltage of a voltage detection circuit, wherein the voltage detection circuit detects an output voltage between two ends of a rectifier circuit, an input end of the rectifier circuit is externally connected to an alternating current, and an output end of the rectifier circuit is connected to a filter circuit; and controlling on-off of the filter circuit according to the detection voltage, wherein the filter circuit comprises a filter capacitor, and the filter circuit is connected to a current conversion circuit.

[0083] Optionally, the method further comprises: controlling on-off of the current conversion circuit according to the detection voltage.

[0084] Optionally, the controlling on-off of the filter circuit according to the detection voltage specifically comprises: judging whether the detection voltage is higher than a first preset threshold; and if the detection voltage is higher than the first preset threshold, controlling the filter circuit to be disconnected.

[0085] The control unit can control on-off of the filter circuit based on the detection voltage of the voltage detection circuit, so that the filter circuit can be disconnected when the voltage input to the filter circuit is too high, thereby reducing damage to the filter capacitor in the circuit, improving the voltage resistance of the transformer without changing the original filter capacitor of the transformer, and further reducing the size of the switch mode power supply using the above-mentioned transformer and reducing the cost of the switch mode power supply.

[0086] The embodiment of the present application further provides a switching mode power supply, which comprises the converter of any one of the above-mentioned embodiments, and the switching of the filter circuit is controlled by the control unit inside the converter, so that the filter capacitor in the filter circuit is prevented from being damaged by overhigh voltage, the volume of the switching mode power supply is reduced, and the cost of the switching mode power supply is lowered.

[0087] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0088] It should be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is indicated only by the appended claims.

Claims

1. A converter, characterized in that, include: The circuit includes a rectifier circuit, a filter circuit, a voltage detection circuit, a control unit, and a current conversion circuit, wherein the filter circuit includes a filter capacitor; The input terminal of the rectifier circuit is connected to an external AC power source, the output terminal of the rectifier circuit is connected to the filter circuit, the filter circuit is connected to the current conversion circuit, the voltage detection circuit detects the output voltage across the rectifier circuit, the control unit is connected to the voltage detection circuit and the filter circuit respectively, and the control unit controls the switching on and off of the filter circuit according to the voltage detected by the voltage detection circuit. The control unit is also connected to the current conversion circuit. The control unit controls the on / off state of the current conversion circuit according to the detected voltage. The current conversion circuit supplies power to the control unit. The current conversion circuit is a DC-DC converter. The control unit controls the switching on and off of the filter circuit based on the detected voltage of the voltage detection circuit, including: The control unit determines whether the detected voltage is higher than a first preset threshold. If the detected voltage is higher than the first preset threshold, the filter circuit is controlled to disconnect. The control unit determines whether the detected voltage is lower than a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; If the detected voltage is lower than the second preset threshold, the filter circuit is turned on. The control unit controls the on / off state of the current conversion circuit based on the detected voltage, including: When the voltage detected by the voltage detection circuit is higher than a third preset threshold, the control unit controls the current conversion circuit to disconnect. When the voltage detected by the voltage detection circuit is lower than a fourth preset threshold, the control unit controls the current conversion circuit to connect. The fourth preset threshold is lower than the third preset threshold.

2. The converter according to claim 1, characterized in that, It also includes an electronic switch, and the filter circuit and the electronic switch are connected in series; The control unit is connected to the electronic switch, and the control unit controls the on / off state of the electronic switch according to the detected voltage.

3. The converter according to claim 1, characterized in that, The rectifier circuit includes a first diode, a second diode, a third diode, and a fourth diode; The first diode and the second diode are connected in series, and the third diode and the fourth diode are connected in series. The positive terminal of the first diode is connected to the positive terminal of the third diode and then connected to one end of the filter circuit. The negative terminal of the second diode is connected to the negative terminal of the fourth diode and then connected to the other end of the filter circuit.

4. The converter according to claim 1, characterized in that, The voltage detection circuit includes a first resistor and a second resistor; One end of the first resistor is connected to one end of the rectifier circuit, and the other end of the first resistor is connected to one end of the second resistor and the control unit, respectively. The other end of the second resistor is connected to the other end of the rectifier circuit.

5. The converter according to claim 2, characterized in that, The electronic switch is a field-effect transistor, thyristor, bipolar junction transistor, or insulated gate bipolar transistor.

6. The converter according to claim 1, characterized in that, Also includes: Third resistor; One end of the third resistor is connected to the power supply, and the other end of the third resistor is connected to the control unit.

7. A converter control method, characterized in that, include: The voltage detection circuit detects the output voltage across the rectifier circuit. The input terminal of the rectifier circuit is connected to an external AC power supply, and the output terminal of the rectifier circuit is connected to a filter circuit. The on / off state of the filter circuit is controlled according to the detected voltage, wherein the filter circuit includes a filter capacitor and is connected to a current conversion circuit; The on / off state of the current conversion circuit is controlled according to the detected voltage. The current conversion circuit supplies power to the control unit. The current conversion circuit is a DC-DC converter. The step of controlling the on / off state of the filter circuit based on the detected voltage specifically includes: Determine whether the detected voltage is higher than a first preset threshold; If the detected voltage is higher than the first preset threshold, the filter circuit is controlled to disconnect. Determine whether the detected voltage is lower than a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; If the detected voltage is lower than the second preset threshold, the filter circuit is turned on. Controlling the on / off state of the current conversion circuit based on the detected voltage specifically includes: If the detected voltage is higher than the third preset threshold, the current conversion circuit is controlled to disconnect. If the detected voltage is lower than the fourth preset threshold, the current conversion circuit is turned on, wherein the fourth preset threshold is lower than the third preset threshold.

8. A switch-mode power supply, characterized in that, Includes the converter as described in any one of claims 1 to 6.

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