A switching power supply circuit and control method for parallel low-voltage input capacitor

Abstract

The present invention discloses a switching power supply circuit and control method of a parallel low-voltage input capacitor, comprising: an input high-voltage capacitor, an input low-voltage capacitor, a first resistor, a second resistor, a third resistor, a voltage detection control module, a switch tube, a rectifier bridge and a transformer; the transformer is used to input AC voltage, the transformer is electrically connected to the rectifier bridge, the rectifier bridge is electrically connected to the first end of the input high-voltage capacitor, the switch tube, the voltage detection control module and the first end of the first resistor, the rectifier bridge is electrically connected to the second end of the input high-voltage capacitor, the first end of the input low-voltage capacitor and the first end of the second resistor, the second end of the input low-voltage capacitor is electrically connected to the switch tube, the switch tube is electrically connected to the voltage detection control module, the voltage detection control module is electrically connected to the second end of the first resistor and the first end of the third resistor, and the second end of the third resistor is electrically connected to the second end of the second resistor. The present invention can reduce the loss of the switching power supply, improve efficiency, and has a simple circuit and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of switch power supply control, and in particular to a switch power supply circuit with a parallel low-voltage input capacitor and a control method. Background Art

[0002] Traditional switching power supplies use smaller transformers by increasing the switching frequency, thereby reducing the size of the power supply. In addition, the electrolytic capacitors of traditional switching power supplies are relatively large, occupying a large part of the internal volume, and often limit the size selection of the adapter design, and the circuit is complex and expensive. Therefore, inventing a high-reliability switching power supply circuit with parallel low-voltage input capacitors has become an urgent problem to be solved by technicians in this field. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a switching power supply circuit and a control method with a parallel low-voltage input capacitor in view of the above-mentioned defects of the prior art.

[0004] In a first aspect, the present invention discloses a switching power supply circuit with a low-voltage input capacitor in parallel, comprising an input high-voltage capacitor, an input low-voltage capacitor, a first resistor, a second resistor, a third resistor, a voltage detection control module, a switch tube, a rectifier bridge and a transformer; the first end and the second end of the transformer are used to input AC voltage, the third end of the transformer is electrically connected to the first end of the rectifier bridge, the fourth end of the transformer is electrically connected to the second end of the rectifier bridge, the third end of the rectifier bridge is respectively electrically connected to the first end of the input high-voltage capacitor, the first end of the switch tube, the first end of the voltage detection control module and the first end of the first resistor, the fourth end of the rectifier bridge is respectively electrically connected to the second end of the input high-voltage capacitor, the first end of the input low-voltage capacitor and the first end of the second resistor, the second end of the input low-voltage capacitor is electrically connected to the second end of the switch tube, the third end of the switch tube is electrically connected to the second end of the voltage detection control module, the third end of the voltage detection control module is electrically connected to the input power supply, the fourth end of the voltage detection control module is respectively electrically connected to the second end of the first resistor and the first end of the third resistor, and the second end of the third resistor is electrically connected to the second end of the second resistor.

[0005] Preferably, the voltage detection control module is implemented by an operational amplifier.

[0006] Preferably, the voltage detection control module is implemented by a comparator.

[0007] Preferably, the voltage detection control module is implemented by an editable logic device.

[0008] Preferably, the switch tube is a metal oxide semiconductor field effect tube MOSFET or an insulated gate bipolar transistor IGBT.

[0009] In a second aspect, the present invention discloses a control method, including a switching power supply circuit with a low-voltage input capacitor in parallel as described in the first aspect, the control method comprising:

[0010] Preset detection foot voltage value;

[0011] Obtaining an input AC voltage value according to the detection pin voltage value;

[0012] Comparing the input AC voltage value with a standard voltage value;

[0013] If the input AC voltage value is lower than the standard voltage value, the switch tube is controlled to be turned on, and the power supply is controlled to distribute the stored energy to the input low-voltage capacitor;

[0014] If the input AC voltage value is higher than the standard voltage value, the switch tube is controlled to be turned off, and the control power supply distributes the stored energy to the input high-voltage capacitor.

[0015] Preferably, the formula for obtaining the input AC voltage value according to the detection foot voltage value includes:

[0016] Vac=Vin_sen*(R1+R2+R3) / R3 / 1.414

[0017] Among them, Vin_sen is the detection pin voltage value, and Vac is the input AC voltage value.

[0018] A switching power supply circuit of a low-voltage input capacitor in parallel of the present invention has the following beneficial effects. A switching power supply circuit of a low-voltage input capacitor in parallel disclosed by the present invention comprises: an input high-voltage capacitor, an input low-voltage capacitor, a first resistor, a second resistor, a third resistor, a voltage detection control module, a switch tube, a rectifier bridge and a transformer; the first end and the second end of the transformer are used to input AC voltage, the third end of the transformer is electrically connected to the first end of the rectifier bridge, the fourth end of the transformer is electrically connected to the second end of the rectifier bridge, the third end of the rectifier bridge is respectively connected to the first end of the input high-voltage capacitor, the first end of the switch tube, the voltage detection control module, the third end of the rectifier bridge and the first end of the input low-voltage capacitor. The first end of the control module is electrically connected to the first end of the first resistor, the fourth end of the rectifier bridge is electrically connected to the second end of the input high-voltage capacitor, the first end of the input low-voltage capacitor and the first end of the second resistor, the second end of the input low-voltage capacitor is electrically connected to the second end of the switch tube, the third end of the switch tube is electrically connected to the second end of the voltage detection control module, the third end of the voltage detection control module is electrically connected to the input power supply, the fourth end of the voltage detection control module is electrically connected to the second end of the first resistor and the first end of the third resistor, respectively, and the second end of the third resistor is electrically connected to the second end of the second resistor. When the input AC voltage is lower than the preset AC voltage threshold, the switch tube is controlled to be turned on, and the power supply allocates most of the energy storage to the low-voltage capacitor, which minimizes the loss and improves the efficiency of the whole machine; when the input AC voltage is higher than the preset AC voltage threshold, the switch tube is controlled to be turned off, and the power supply allocates the energy storage to the input high-voltage capacitor, and the input high-voltage capacitor supports the output of the power supply. Therefore, the present invention can effectively reduce the loss of the switching power supply, improve efficiency, and has a simple circuit and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. 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 these drawings without creative work:

[0020] Figure 1 It is a circuit diagram of a switching power supply circuit with a low-voltage input capacitor in parallel according to a preferred embodiment of the present invention;

[0021] Figure 2 The present invention is a flow chart of a control method for a switching power supply circuit with a low-voltage input capacitor in parallel according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0023] Embodiment 1

[0024] The preferred embodiment of the present invention is as follows Figure 1 As shown, it includes an input high-voltage capacitor C1, an input low-voltage capacitor C2, a first resistor R3, a second resistor R1, a third resistor R2, a voltage detection control module U1, a switch tube Q1, a rectifier bridge BD1 and a transformer LF1; the first end and the second end of the transformer LF1 are used to input AC voltage, the third end of the transformer LF1 is electrically connected to the first end of the rectifier bridge BD1, the fourth end of the transformer LF1 is electrically connected to the second end of the rectifier bridge BD1, and the third end of the rectifier bridge BD1 is respectively connected to the first end of the input high-voltage capacitor C1, the first end of the switch tube Q1, the first end of the voltage detection control module U1 and the first end of the first resistor R3. The fourth end of the rectifier bridge BD1 is electrically connected to the second end of the input high-voltage capacitor C1, the first end of the input low-voltage capacitor C2 and the first end of the second resistor R1, the second end of the input low-voltage capacitor C2 is electrically connected to the second end of the switch tube Q1, the third end of the switch tube Q1 is electrically connected to the second end of the voltage detection control module U1, the third end of the voltage detection control module U1 is electrically connected to the input power supply, the fourth end of the voltage detection control module U1 is electrically connected to the second end of the first resistor R3 and the first end of the third resistor R2, respectively, and the second end of the third resistor R2 is electrically connected to the second end of the second resistor R1. When the input AC voltage is lower than the preset AC voltage threshold, the switch tube Q1 is controlled to be turned on, and the power supply allocates most of the energy storage to the low-voltage capacitor, which minimizes the loss and improves the efficiency of the whole machine; when the input AC voltage is higher than the preset AC voltage threshold, the switch tube Q1 is controlled to be turned off, and the power supply allocates the energy storage to the input high-voltage capacitor C1, and the input high-voltage capacitor C1 supports the output of the power supply. Therefore, the present invention can effectively reduce the loss of the switching power supply, improve the efficiency, and has a simple circuit and low cost.

[0025] Preferably, the voltage detection control module detects the input AC voltage, and controls the switch tube Q1 to turn on when the input AC voltage is lower than the preset AC voltage threshold; and controls the switch tube Q1 to turn off when the input AC voltage is higher than the preset AC voltage threshold. In this embodiment, the preset AC voltage threshold is 132Vac. In addition, the input high-voltage capacitor C1 capacity = output power * 0.5uF described in this embodiment; the input low-voltage capacitor C2 capacity = output power * 1.5uF. In an embodiment, the input high-voltage capacitor C1 capacity is 400V, and the input low-voltage capacitor C2 is 200V.

[0026] Preferably, the voltage detection control module U1 is implemented by an operational amplifier.

[0027] Preferably, the voltage detection control module U1 is implemented by a comparator.

[0028] Preferably, the voltage detection control module U1 is implemented by an editable logic device.

[0029] Preferably, the switch tube Q1 is a metal oxide semiconductor field effect tube MOSFET or an insulated gate bipolar transistor IGBT.

[0030] Embodiment 2

[0031] The present invention discloses a control method, please refer to Figure 2 , including a switching power supply circuit with a low-voltage input capacitor in parallel as described in Embodiment 1, the control method includes:

[0032] S1, preset detection foot voltage value;

[0033] S2, obtaining an input AC voltage value according to the detection foot voltage value;

[0034] S3, comparing the input AC voltage value with the standard voltage value;

[0035] S4. If the input AC voltage value is lower than the standard voltage value, the switch tube is controlled to be turned on, and the power supply is controlled to distribute the stored energy to the input low-voltage capacitor;

[0036] S5. If the input AC voltage value is higher than the standard voltage value, the switch tube is controlled to be turned off, and the power supply is controlled to distribute the stored energy to the input high-voltage capacitor.

[0037] Preferably, the formula for obtaining the input AC voltage value according to the detection foot voltage value includes:

[0038] Vac=Vin_sen*(R1+R2+R3) / R3 / 1.414

[0039] Among them, Vin_sen is the detection pin voltage value, and Vac is the input AC voltage value.

[0040] In summary, the switching power supply circuit of a parallel low-voltage input capacitor provided by the present invention includes an input high-voltage capacitor C1, an input low-voltage capacitor C2, a first resistor R3, a second resistor R1, a third resistor R2, a voltage detection control module U1, a switch tube Q1, a rectifier bridge BD1 and a transformer LF1; when the input AC voltage is lower than the preset AC voltage threshold, the switch tube Q1 is controlled to be turned on, and the power supply allocates most of the energy storage to the low-voltage capacitor, which minimizes the loss and improves the efficiency of the whole machine; when the input AC voltage is higher than the preset AC voltage threshold, the switch tube Q1 is controlled to be turned off, and the power supply allocates the energy storage to the input high-voltage capacitor C1, and the input high-voltage capacitor C1 supports the output of the power supply. Therefore, the present invention can effectively reduce the loss of the switching power supply, improve efficiency, and has a simple circuit and low cost.

[0041] The above is a detailed introduction to a switching power supply circuit and control method of a parallel low-voltage input capacitor provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present invention; at the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification is only the implementation method of the present invention, and does not limit the patent scope of the present invention. All equivalent structures or equivalent process changes made by using the contents of the present invention specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present invention. It should not be understood as a limitation of the present invention.

Claims

1. A switching power supply circuit with a low voltage input capacitor in parallel, characterized in that: include: An input high-voltage capacitor, an input low-voltage capacitor, a first resistor, a second resistor, a third resistor, a voltage detection control module, a switch tube, a rectifier bridge and a transformer; the first end and the second end of the transformer are used to input AC voltage, the third end of the transformer is electrically connected to the first end of the rectifier bridge, the fourth end of the transformer is electrically connected to the second end of the rectifier bridge, the third end of the rectifier bridge is respectively electrically connected to the first end of the input high-voltage capacitor, the first end of the switch tube, the first end of the voltage detection control module and the first end of the first resistor, the fourth end of the rectifier bridge is respectively electrically connected to the second end of the input high-voltage capacitor, the first end of the input low-voltage capacitor and the first end of the second resistor, the input low The second end of the voltage capacitor is electrically connected to the second end of the switch tube, the third end of the switch tube is electrically connected to the second end of the voltage detection control module, the third end of the voltage detection control module is electrically connected to the input power supply, the fourth end of the voltage detection control module is electrically connected to the second end of the first resistor and the first end of the third resistor respectively, and the second end of the third resistor is electrically connected to the second end of the second resistor; the voltage detection control module is implemented by an operational amplifier, or the voltage detection control module is implemented by a comparator, or the voltage detection control module is implemented by an editable logic device; the switch tube is a metal oxide semiconductor field effect tube MOSFET or an insulated gate bipolar transistor IGBT.

2. A control method, comprising the switching power supply circuit of claim 1 with a low-voltage input capacitor in parallel, the method comprising: Preset detection foot voltage value; Obtaining an input AC voltage value according to the detection pin voltage value; Comparing the input AC voltage value with a standard voltage value; If the input AC voltage value is lower than the standard voltage value, the switch tube is controlled to be turned on, and the power supply is controlled to distribute the stored energy to the input low-voltage capacitor; If the input AC voltage value is higher than the standard voltage value, the switch tube is controlled to be turned off, and the control power supply distributes the stored energy to the input high-voltage capacitor.

3. The control method according to claim 2, characterized in that: The formula for obtaining the input AC voltage value according to the detection foot voltage value includes: Vac=Vin_sen*(R1+R2+R3) / R3 / 1.414 Among them, Vin_sen is the detection pin voltage value, and Vac is the input AC voltage value.

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