CN104660044B

CN104660044B - A kind of switching circuit, the method and device for controlling switching circuit

Info

Publication number: CN104660044B
Application number: CN201410829573.5A
Authority: CN
Inventors: 王再兴
Original assignee: Xian Huawei Technologies Co Ltd
Current assignee: Xian Huawei Technologies Co Ltd
Priority date: 2014-12-26
Filing date: 2014-12-26
Publication date: 2018-07-03
Anticipated expiration: 2034-12-26
Also published as: CN104660044A

Abstract

The embodiment of the present invention provides a kind of switching circuit, the method and device for controlling switching circuit, is related to circuit field, for improving the compatibility of Switching Power Supply.The circuit includes：It is connected in parallel on the first bridge arm, the second bridge arm and capacitive branch of both ends of power；First bridge arm includes the first switch and second switch of series connection, and the second bridge arm includes the third switch of series connection and the 4th switch, capacitive branch include the first capacitance and the second capacitance of series connection；5th switch；One end of 5th switch is connected between the first capacitance and the second capacitance, and the other end of the 5th switch is connected between first switch and second switch；Voltage regulating rectification circuit；The first input end of voltage regulating rectification circuit is connected between first switch and the second switch, and the second input terminal of voltage regulating rectification circuit is connected to third switch and the 4th switch room；When the 5th switch conduction, first switch and second switch disconnect, Switching Power Supply is operated in half-bridge mode；When the 5th switch disconnects, Switching Power Supply is operated in full-bridge mode.

Description

Switching circuit, method and device for controlling switching circuit

Technical Field

The present invention relates to the field of circuits, and in particular, to a switching circuit, a method and an apparatus for controlling the switching circuit.

Background

The circuit topology of the switching power supply has a plurality of structures, and the common circuit topology has the forms of push-pull, full bridge, half bridge, single-ended forward, single-ended flyback and the like. Among them, the switching power supply of the full-bridge topology is widely used with high cost performance.

The switching power supply of the full-bridge topology comprises a full-bridge circuit consisting of 4 electronic switching devices, and when the switching power supply of the full-bridge topology works, the 4 electronic switching devices are all alternately switched on, so that the switching power supply of the full-bridge topology works in a full-bridge mode.

The switching power supply of the half-bridge topology comprises a half-bridge point circuit consisting of 2 electronic switching devices, and when the switching power supply of the half-bridge topology works, the 2 electronic switching devices are alternately switched on, so that the switching power supply of the half-bridge topology works in a half-bridge mode.

However, the switching power supply of the full-bridge topology can only work in the full-bridge mode, and the switching power supply of the half-bridge topology can only work in the half-bridge mode; that is to say, the switching power supply of the full-bridge topology in the prior art cannot be compatible with the half-bridge mode, and the switching power supply of the half-bridge topology cannot be compatible with the full-bridge mode, so that the problem of poor compatibility of the switching power supply is caused.

Disclosure of Invention

The embodiment of the invention provides a switching circuit, a method and a device for controlling the switching circuit, which are used for improving the compatibility of a switching power supply.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

in a first aspect, an embodiment of the present invention provides a switching circuit, applied to a switching power supply, including: a power source; the first bridge arm, the second bridge arm and the capacitor branch are connected in parallel at two ends of the power supply; the first bridge arm comprises a first switch and a second switch which are connected in series, the second bridge arm comprises a third switch and a fourth switch which are connected in series, and the capacitor branch comprises a first capacitor and a second capacitor which are connected in series; a fifth switch; one end of the fifth switch is connected between the first capacitor and the second capacitor, and the other end of the fifth switch is connected between the first switch and the second switch; a voltage regulating rectification circuit; the first input end of the voltage-regulating rectification circuit is connected between the first switch and the second switch, and the second input end of the voltage-regulating rectification circuit is connected between the third switch and the fourth switch; the switching power supply operates in a half-bridge mode under the condition that the fifth switch is turned on and the first switch and the second switch are turned off; the switching power supply operates in a full-bridge mode with the fifth switch open.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the circuit further includes: a control circuit; the control circuit is respectively connected with the first switch, the second switch, the third switch, the fourth switch and the fifth switch; the control circuit is configured to turn on the fifth switch, turn off the first switch and the second switch, and control the switching power supply to operate in a half-bridge mode; the control circuit is further configured to turn off the fifth switch and control the switching power supply to operate in a full-bridge mode.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the control circuit is further configured to obtain voltages at two ends of the power supply and a voltage output by the voltage regulating and rectifying circuit, and determine a dc gain of the switching circuit according to the voltages at two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit; the current acquisition circuit is also used for acquiring the current at a preset position of the switching circuit; the preset position of the switch circuit comprises the power supply end or the output end of the voltage-regulating rectifying circuit; the control circuit is further configured to, when it is determined that the dc gain of the switching circuit is smaller than a first preset value and/or the current at a preset position of the switching circuit is smaller than a second preset value, turn on the fifth switch, turn off the first switch and the second switch, and control the switching power supply to operate in a half-bridge mode; and under the condition that the direct current gain of the switch circuit is determined to be larger than the first preset value and/or the current at the preset position of the switch circuit is determined to be larger than the second preset value, the fifth switch is switched off, and the switch power supply is controlled to work in a full-bridge mode.

With reference to the first aspect, or the first or second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the circuit further includes: a third capacitor; and the third capacitor is connected in series with a line connecting the first input end of the voltage-regulating rectification circuit and the third switch.

With reference to the first aspect or any one of the first to third possible implementation manners of the first aspect, in a fourth possible implementation manner of the first aspect, the voltage regulating and rectifying circuit includes: a transformer.

With reference to the first aspect or any one of the first to fourth possible implementation manners of the first aspect, in a fifth possible implementation manner of the first aspect, the voltage regulating and rectifying circuit includes: LLC resonant circuit.

In a second aspect, an embodiment of the present invention provides a method for controlling a switch circuit, where the method is applied to the switch circuit described in the above embodiment, and includes: switching on the fifth switch, switching off the first switch and the second switch, and controlling the switching power supply to work in a half-bridge mode; or, the fifth switch is turned off, and the switching power supply is controlled to work in a full-bridge mode.

With reference to the second aspect, in a first possible implementation manner of the second aspect, before turning on the fifth switch or before turning off the fifth switch, the method further includes: acquiring the voltage at two ends of a power supply and the voltage output by a voltage regulating and rectifying circuit, and determining the direct current gain of the switch circuit according to the voltage at two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit; and/or, obtaining a current at a preset position of the switching circuit; the preset position of the switch circuit comprises the power supply end or the output end of the voltage-regulating rectifying circuit; the turning on the fifth switch, turning off the first switch and the second switch, and controlling the switching power supply to operate in the half-bridge mode includes: under the condition that the direct current gain of the switching circuit is determined to be smaller than a first preset value and/or the current at a preset position of the switching circuit is determined to be smaller than a second preset value, the fifth switch is turned on, the first switch and the second switch are turned off, and the switching power supply is controlled to work in a half-bridge mode; the turning off the fifth switch and controlling the switching power supply to operate in a full-bridge mode includes: and when the direct current gain of the switch circuit is determined to be larger than the first preset value and/or the current at the preset position of the switch circuit is determined to be larger than the second preset value, the fifth switch is switched off, and the switch power supply is controlled to work in a full-bridge mode.

In a third aspect, an embodiment of the present invention provides a method for controlling a switching circuit, which is applied to a switching power supply including the switching circuit, where the switching circuit includes: the power supply, a first bridge arm, a second bridge arm, a third capacitor and a voltage-regulating rectifying circuit are connected with the power supply in parallel; the first bridge arm comprises a first switch and a second switch which are connected in series; the second bridge arm comprises a third switch and a fourth switch which are connected in series; the first input end of the voltage-regulating rectification circuit is connected between the first switch and the second switch, and the second input end of the voltage-regulating rectification circuit is connected between the third switch and the fourth switch; the method comprises the following steps: controlling the switching power supply to work in a full-bridge mode; or, the third switch is turned off, the fourth switch is turned on, and the switching power supply is controlled to work in a half-bridge mode.

With reference to the third aspect, in a first possible implementation manner of the third aspect, before the controlling the switching power supply to operate in the full-bridge mode, or before the turning off the third switch, the method further includes: acquiring the voltage at two ends of a power supply and the voltage output by a voltage regulating and rectifying circuit, and determining the direct current gain of the switch circuit according to the voltage at two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit; and/or, obtaining a current at a preset position of the switching circuit; the preset position of the switch circuit comprises the power supply end or the output end of the voltage-regulating rectifying circuit; the turning off the third switch, turning on the fourth switch, and controlling the switching power supply to operate in the half-bridge mode includes: when the direct current gain of the switch circuit is determined to be smaller than the first preset value and/or the current at the preset position of the switch circuit is determined to be smaller than the second preset value, the third switch is turned off, the fourth switch is turned on, and the switch power supply is controlled to work in a half-bridge mode; the controlling the switching power supply to work in a full-bridge mode comprises: and controlling the switching power supply to work in a full-bridge mode when the direct-current gain of the switching circuit is determined to be larger than the first preset value and/or the current at the preset position of the switching circuit is determined to be larger than the second preset value.

In a fourth aspect, an embodiment of the present invention provides a switching power supply, including a filter circuit and the switching circuit described in the foregoing embodiment; the switch circuit is connected with the filter circuit; and the filter circuit is used for filtering the voltage output by the switch circuit.

The embodiment of the invention provides a switching circuit, a method and a device for controlling the switching circuit, wherein the switching circuit is applied to a switching power supply and comprises the following steps: the power supply, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the first capacitor, the second capacitor and the voltage-regulating rectification circuit, wherein under the condition that the fifth switch is conducted and the first switch and the second switch are disconnected, the switching power supply can work in a half-bridge mode at the moment as only the third switch and the fourth switch are arranged; under the condition that the fifth switch is disconnected, the switching power supply further comprises a first switch, a second switch, a third switch and a fourth switch, and the switching power supply can work in a full-bridge mode at the moment. Therefore, the switching power supply provided by the invention can work in a full-bridge mode and also can work in a half-bridge mode, so that the compatibility of the switching power supply is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a switching circuit according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of another switching circuit according to an embodiment of the present invention;

fig. 10 is a diagram illustrating an example of a switch circuit according to an embodiment of the present invention;

fig. 11 is a flowchart illustrating a method for controlling a switch circuit according to an embodiment of the present invention;

FIG. 12 is a schematic flow chart illustrating another method for controlling a switch circuit according to an embodiment of the present invention;

fig. 13 is a schematic flowchart of another method for controlling a switch circuit according to an embodiment of the present invention;

fig. 14 is a schematic flow chart illustrating another method for controlling a switch circuit according to an embodiment of the present invention;

FIG. 15 is a schematic flow chart illustrating another method for controlling a switch circuit according to an embodiment of the present invention;

fig. 16 is a schematic structural diagram of a switching power supply according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

An embodiment of the present invention provides a switching circuit, as shown in fig. 1, including: the power supply 101 is connected with a first bridge arm a, a second bridge arm b and a capacitor branch c at two ends of the power supply 101 in parallel; the first bridge arm a includes a first switch 102 and a second switch 103 connected in series, the second bridge arm b includes a third switch 104 and a fourth switch 105 connected in series, and the circuit further includes: a fifth switch 106, the capacitance branch c comprises a first capacitor 107 and a second capacitor 108 connected in series; one end of the fifth switch 106 is connected between the first capacitor 107 and the second capacitor 108, and the other end of the fifth switch 106 is connected between the first switch 102 and the second switch 103; further comprising: a voltage-regulating rectification circuit 109; the first input end of the voltage regulating rectifying circuit 109 is connected between the first switch 102 and the second switch 103, and the second input end of the voltage regulating rectifying circuit 109 is connected between the third switch 104 and the fourth switch 105.

When the fifth switch 106 is turned on and the first switch 102 and the second switch 103 are turned off, the switching power supply operates in a half-bridge mode; with the fifth switch 106 open, the switching power supply operates in full-bridge mode.

Specifically, when the fifth switch 106 is turned on and the first switch 102 and the second switch 103 are turned off, the circuit diagram shown in fig. 1 is equivalent to the circuit diagram shown in fig. 2, and it can be seen that the switches in fig. 2 include the third switch 104 and the fourth switch 105 connected in series on the second leg b, at this time, the third switch 104 and the fourth switch 105 are controlled according to the alternating on mode of the duty ratio a and the frequency f1, that is, when the third switch 104 is controlled to be turned on, the fourth switch 105 is controlled to be turned off; when the third switch 104 is controlled to be off, the fourth switch 105 is controlled to be on. The specific process of alternating conduction is as follows: the power supply 101 charges the first capacitor 107 and the second capacitor 108, that is, the voltage across the first capacitor 107 and the voltage across the second capacitor 108 are both half of the output voltage of the power supply 101, when the third switch 104 is turned on and the fourth switch 105 is turned off, the first capacitor 107 is used as the power supply, and the output direct current passes through the third switch 104 and the voltage regulating rectification circuit 109 in sequence, that is, the direction of the current flowing into the voltage regulating rectification circuit 109 is from the positive pole to the negative pole of the power supply 101 relative to the power supply 101; when the third switch 104 is turned off and the fourth switch 105 is turned on, the second capacitor 107 serves as a power supply, and the output direct current passes through the voltage-regulating rectifying circuit 109 and the third switch 104 in this order, that is, the direction of the current flowing into the voltage-regulating rectifying circuit 109 is from the negative electrode to the positive electrode of the power supply 101 with respect to the power supply 101, so that the alternating current is generated at the input end of the voltage-regulating rectifying circuit 109, and the alternating current is transformed and rectified and then output. Since the switching circuit in the switching power supply is alternately turned on by the third switch 104 and the fourth switch 105, the switching power supply operates in a half-bridge mode.

When the fifth switch 106 is turned on, the circuit diagram shown in fig. 1 is equivalent to the circuit diagram shown in fig. 3, and it can be seen that the circuit diagram shown in fig. 3 is a full bridge circuit in the prior art, and specifically, reference may be made to a method for controlling a full bridge circuit in the prior art, which is not repeated herein.

It should be noted that the first switch 102, the second switch 103, the third switch 104, the fourth switch 105 and the fifth switch 106 can be controlled to be turned on and off by the control circuit; the first switch 102, the second switch 103, the third switch 104, the fourth switch 105 and the fifth switch 106 may also be controlled to be turned on or off manually by a user, which is not limited in the present invention.

It should be noted that, the polarity of the two ends of the power supply 101 is not limited in the present invention, and one end of the first capacitor 107 in the capacitor branch c may be connected to the positive electrode of the power supply 101, and one end of the second capacitor 108 may be connected to the negative electrode of the power supply 101; one end of the first capacitor 107 may be connected to the negative electrode of the power source 101, and one end of the second capacitor 108 may be connected to the positive electrode of the power source 101. In the embodiments and the drawings of the present invention, one end of the first capacitor 107 in the capacitor branch c is connected to the positive electrode of the power supply 101, and one end of the second capacitor 108 is connected to the negative electrode of the power supply 101.

It should be noted that the connection manner of the first bridge arm a and the second bridge arm b is not limited in the present invention, and the first bridge arm a may be connected between the capacitive branch c and the second bridge arm b, as shown in fig. 1; the second arm b may be connected between the capacitive branch c and the first arm a.

In addition, the present invention does not limit the positional relationship between the first switch 102 and the second switch 103 connected in series in the first arm a, and the positional relationship between the third switch 104 and the fourth switch 105 connected in series in the second arm b. That is, one end of the first switch 102 and one end of the third switch 104 may be connected to the positive electrode of the power source 101; one end of the second switch 103 and one end of the fourth switch 105 may be connected to the positive electrode of the power supply 101; one end of the first switch 102 and one end of the fourth switch 105 may be connected to the positive electrode of the power supply 101; one end of the second switch 103 and one end of the third switch 104 may be connected to the positive electrode of the power source 101, and fig. 1 shows only one schematic diagram. The following examples and drawings are described by way of example of the connection shown in fig. 1.

It should be noted that the voltage regulating and rectifying circuit 109 includes a voltage regulating circuit and a rectifying circuit, and both the voltage regulating circuit and the rectifying circuit are those in the prior art.

The embodiment of the invention provides a switching circuit, which is applied to a switching power supply and comprises: the power supply, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the first capacitor, the second capacitor and the voltage-regulating rectification circuit, wherein under the condition that the fifth switch is conducted and the first switch and the second switch are disconnected, the switching power supply can work in a half-bridge mode at the moment as only the third switch and the fourth switch are arranged; under the condition that the fifth switch is disconnected, the switching power supply further comprises a first switch, a second switch, a third switch and a fourth switch, and the switching power supply can work in a full-bridge mode at the moment. Therefore, the switching power supply provided by the invention can work in a full-bridge mode and also can work in a half-bridge mode, so that the compatibility of the switching power supply is improved.

Further, as shown in fig. 4, the switching circuit further includes: a third capacitor 110.

The third capacitor 110 is connected in series to a line connecting the first input terminal of the voltage-regulating rectifying circuit 109 and the third switch 104.

Specifically, when the switch circuit includes the third capacitor 110, the first capacitor 107 and the second capacitor 108 having larger capacitance values may be selected.

Preferably, as shown in fig. 5, the switching circuit further includes: a control circuit 111.

The control circuit 111 is connected to the first switch 102, the second switch 103, the third switch 104, the fourth switch 105, and the fifth switch 106, respectively.

The control circuit 111 is configured to turn on the fifth switch 106, turn off the first switch 102 and the second switch 103, and control the switching power supply to operate in a half-bridge mode.

The control circuit 111 is further configured to turn off the fifth switch 106 and control the switching power supply to operate in a full-bridge mode.

Further, the control circuit 111 is further configured to obtain a voltage across the power supply 101 and a voltage output by the voltage regulating and rectifying circuit 109, and determine a dc gain of the switching circuit according to the voltage across the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109; and is also used to obtain the current at the preset position of the switching circuit.

The preset position of the switch circuit comprises a power supply 101 end or an output end of the voltage regulating rectification circuit 109.

As shown in fig. 6, the control circuit 111 includes: a voltage acquisition unit 1110, a current acquisition unit 1111, and a control unit 1112.

The input end of the voltage acquisition unit 1110 is respectively connected with the two ends of the power supply 101 and the output end of the voltage regulating rectification circuit 109; the input end of the current collection unit 1111 is connected with the two ends of the power supply 101 and the output end of the voltage regulation and rectification circuit 109 respectively; the control unit 1112 is connected to the output terminals of the voltage acquisition unit 1110 and the current acquisition unit 1111, respectively.

Specifically, the voltage collecting unit 1110 is configured to collect the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109; the current collecting unit 1111 is used for collecting input current of the power supply 101 or current output by the voltage regulating rectification circuit 109; the control unit 1112 is configured to receive the voltage across the power source 101 and the voltage output from the output of the voltage regulating and rectifying circuit 109 collected by the voltage collecting unit 1110, and the input current of the power source 101 or the current output from the output of the voltage regulating and rectifying circuit 109 collected by the current collecting unit 1111.

It should be noted that, the specific voltage collecting unit 1110 is composed of a voltage collecting circuit in the prior art, the current collecting unit 1111 is composed of a current collecting circuit in the prior art, and the control unit 1112 is composed of a control circuit in the prior art, which is not described herein again.

The control circuit 111 is further configured to, when it is determined that the dc gain of the switching circuit is smaller than a first preset value and/or the current at a preset position of the switching circuit is smaller than a second preset value, turn on the fifth switch 106, turn off the first switch 102 and the second switch 103, and control the switching power supply to operate in the half-bridge mode.

The first preset value is determined according to different decision-making factors, and when the decision-making factors are only the direct current gain of the switch circuit, the first preset value is a certain fixed value; when the decision-making factors include the input current of the switching circuit or the output current of the switching circuit in addition to the dc gain of the switching circuit, the determined first preset value is also a variation value that varies according to the input current or the output current of the switching circuit, since the dc gain of the switching circuit varies with the variation of the input current or the output current of the switching circuit. The second preset value is selected according to different preset positions, and the selected value is also different fixed values. And the basis for specifically determining the first preset value and the second preset value is determined according to the conversion efficiency of the switching power supply being optimal.

Preferably, as shown in fig. 7, the voltage regulating rectifier circuit 109 includes: and a transformer 109 a.

The first input end of the voltage regulating rectification circuit 109 is connected between the first switch 102 and the second switch 103, and the second input end of the voltage regulating rectification circuit 109 is connected between the third switch 104 and the fourth switch 105, and the voltage regulating rectification circuit comprises:

a first terminal of the primary winding of the transformer 109a is connected between the first switch 102 and the second switch 103, and a second terminal of the primary winding of the transformer 109a is connected between the third switch 104 and the fourth switch 105.

When the voltage regulating and rectifying circuit 109 includes the transformer 109a, components such as a capacitor may be connected in series to the transformer 109a, which is not limited in the present invention.

Alternatively, as shown in fig. 8, the voltage-regulating rectifier circuit 109 includes: the LLC resonant circuit 109 b. Wherein, the LLC resonant circuit 109b includes: a first inductor L1, a resonant inductor L2 and a fourth capacitor C1.

a first end of the first inductor L1 is connected between the first switch 102 and the second switch 103, and a second end of the first inductor L1 is connected with a first end of the fourth capacitor C1; a second end of the fourth capacitor C1 is connected with a first end of the resonant inductor L2; the second terminal of the resonant inductor L2 is connected between the third switch 104 and the fourth switch 105.

Preferably, the first capacitor 107 and the second capacitor 108 are capacitors with equal capacitance.

It should be noted that the voltage regulating and rectifying circuit 109 may also be composed of other resonant circuits and rectifying circuits, for example, a series resonant circuit, a parallel resonant circuit, or the like, which is not limited in the present invention.

Specifically, in the case where the voltage-regulating rectifying circuit 109 includes the transformer 109a, when the control circuit 111 receives only the voltage across the power source 101 and the voltage output from the voltage-regulating rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage across the power supply 101 is obtained to obtain the DC gain of the switching circuit, and comparing the obtained DC gain with a first preset value stored in advance, when the obtained DC gain is determined to be smaller than the first preset value, the voltage-regulating rectification circuit 109 controls the fifth switch 106 to be on, controls the first switch 102 and the second switch 103 to be off, and according to the voltage output by the voltage-regulating rectification circuit 109 and the voltage at the two ends of the power supply 101, the third switch 104 and the fourth switch 105 are controlled according to the pulse signal with the duty ratio of a and the frequency of f1, wherein when the third switch 104 is controlled to be turned on, the fourth switch 105 is controlled to be turned off; when the third switch 104 is controlled to be off, the fourth switch 105 is controlled to be on. The specific process of alternating conduction is as follows: the power supply 101 charges the first capacitor 107 and the second capacitor 108, that is, the voltage across the first capacitor 107 and the voltage across the second capacitor 108 are both half of the output voltage of the power supply 101, and when the third switch 104 is turned on and the fourth switch 105 is turned off, the first capacitor 107 is used as the power supply, and the output direct current passes through the third switch 104 in sequence, and the direction of the current flowing into the primary winding of the transformer 109a, that is, the primary winding of the transformer 109a, is from the positive electrode to the negative electrode of the power supply 101 with respect to the power supply 101; when the third switch 104 is turned off and the fourth switch 105 is turned on, the second capacitor 107 is used as a power supply to pass the output dc current through the primary winding of the transformer 109a in sequence, and the third switch 104, i.e., the direction of the current flowing into the primary winding of the transformer 109a, is from the negative pole to the positive pole of the power supply 101 with respect to the power supply 101, so that the ac current is generated in the primary winding of the transformer 109a, transformed by the transformer 109a, and then output from the secondary winding of the transformer 109 a.

When the control circuit 111 only receives the input current of the power supply 101 or the current output by the output end of the voltage regulating and rectifying circuit 109, the control circuit 111 determines whether the received input current of the power supply 101 or the current output by the output end of the voltage regulating and rectifying circuit 109 is smaller than a second pre-stored preset value, and if the determined current is smaller than the second pre-stored preset value, the specific process is the same as the process when only the dc gain is determined to be smaller than the first preset value, which is not repeated herein.

When the control circuit 111 receives the voltage at the two ends of the power supply 101 and the voltage output by the output end of the voltage regulating and rectifying circuit 109, and also receives the input current of the power supply 101, or the current output by the output end of the voltage regulating and rectifying circuit 109, when determining that the dc gain is smaller than the first preset value, the control circuit 111 needs to determine whether the received input current of the power supply 101, or the current output by the output end of the voltage regulating and rectifying circuit 109, is smaller than a second preset value stored in advance, and if determining that the dc gain is smaller than the second preset value stored in advance, the specific process is the same as the process when only determining that the dc gain is smaller than the first preset value, which is not repeated herein.

It should be noted that the value of the duty ratio a is usually less than 0.5, and the time interval for the control circuit 111 to control the third switch 104 and the fourth switch 105 to conduct alternately is 0.5-a.

Under the condition that the voltage regulating and rectifying circuit 109 comprises the LLC resonant circuit 109b, when the control circuit 111 only receives the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage at two ends of the power supply 101 is obtained, the direct current gain of the switch circuit is obtained, the obtained direct current gain is compared with a first preset value stored in advance, when the obtained direct current gain is determined to be smaller than the first preset value, the voltage regulating and rectifying circuit 109 controls the fifth switch 106 to be switched on, the first switch 102 and the second switch 103 to be switched off, the third switch 104 and the fourth switch 105 are controlled according to the alternating-on pulse signal with the duty ratio of b and the frequency of f2 and the voltage at two ends of the power supply 101, namely when the third switch 104 is controlled to be switched on, the fourth switch 105 is controlled to be switched off; when the third switch 104 is controlled to be off, the fourth switch 105 is controlled to be on. The specific process of alternating conduction is as follows: the power supply 101 charges the first capacitor 107 and the second capacitor 108, that is, the voltage across the first capacitor 107 and the voltage across the second capacitor 108 are both half of the output voltage of the power supply 101, when the third switch 104 is turned on and the fourth switch 105 is turned off, the first capacitor 107 is used as the power supply, and the output direct current passes through the third switch 104, the first inductor L1 of the LLC resonant circuit 109b, the fourth capacitor C1 and the resonant inductor L2, that is, the direction of the current flowing into the resonant inductor of the LLC resonant circuit 109b is from the positive pole to the negative pole of the power supply 101 relative to the power supply 101; when the third switch 104 is turned off and the fourth switch 105 is turned on, the second capacitor 107 serves as a power supply, and the output direct current passes through the resonant inductor L2 of the LLC resonant circuit 109b, the fourth capacitor C1, the first inductor L1, the third switch 104, that is, the direction of the current flowing through the resonant inductor L2 of the LLC resonant circuit 109b is from the negative electrode to the positive electrode of the power supply 101 with respect to the power supply 101, so that the resonant inductor L2 of the LLC resonant circuit 109b generates and outputs an alternating current.

It should be noted that, in the case that the voltage regulating and rectifying circuit 109 includes the LLC resonant circuit 109b, when the control circuit 111 only receives the input current of the power supply 101, or the current output by the output terminal of the voltage regulating and rectifying circuit 109, or when the control circuit 111 receives the voltage across the power supply and the voltage output by the output terminal of the voltage regulating and rectifying circuit 109, and also receives the input current of the power supply 101, or the current output by the output terminal of the voltage regulating and rectifying circuit 109, the specific process is the same as that in the case that the voltage regulating and rectifying circuit 109 includes the transformer 109a, and the description of the present invention is omitted here.

It should be noted that, theoretically, the value of the duty ratio b is usually 0.5, and in an actual circuit, in order to avoid that the third switch 104 and the fourth switch 105 are turned on or off simultaneously, the control circuit 111 controls the fourth switch 105 to be turned on after a dead time when controlling the third switch 104 to be turned off; when the fourth switch 105 is controlled to be turned off, the third switch 104 is controlled to be turned on after a dead time, so that the value of the duty ratio b is slightly smaller than 0.5.

Further, the control circuit 111 is further configured to turn off the fifth switch 106 and control the switching power supply to operate in a full-bridge mode when it is determined that the dc gain of the switching circuit is greater than the first preset value and/or the current at the preset position of the switching circuit is greater than the second preset value.

Specifically, in the case that the voltage regulating and rectifying circuit 109 includes the transformer 109a, when the control circuit 111 receives only the voltage across the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage across the power supply 101 is obtained, the dc gain of the switching circuit is obtained, the obtained dc gain is compared with a first preset value stored in advance, when it is determined that the obtained dc gain is greater than the first preset value, the fifth switch 106 is controlled to be turned off, and the first switch 102 and the fourth switch 105, the second switch 103 and the third switch 104 are controlled to be turned off according to the pulse signal with the duty ratio of c and the frequency of f3, that is, when the first switch 102 and the fourth switch 105 are controlled to be turned on, the second switch 103 and the third switch 104 are controlled to be turned off; when the first switch 102 and the fourth switch 105 are controlled to be turned off, the second switch 103 and the third switch 104 are controlled to be turned on. The specific process of the alternate conduction is the same as the process of the alternate conduction of the full bridge circuit using the transformer 109a in the prior art, and the description of the present invention is omitted here.

It should be noted that the value of the duty ratio c is usually less than 0.5, and the time interval for the control circuit 111 to control the third switch 104 and the fourth switch 105 to conduct alternately is 0.5-c.

Under the condition that the voltage regulating and rectifying circuit 109 comprises the LLC resonant circuit 109b, when the control circuit 111 only receives the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage at two ends of the power supply 101 is obtained, the direct current gain of the switching circuit is obtained, the obtained direct current gain is compared with a first preset value stored in advance, when the obtained direct current gain is determined to be greater than the first preset value, the fifth switch 106 is controlled to be switched off, the first switch 102 and the fourth switch 105 are controlled according to a pulse signal with the duty ratio of d and the frequency of f4, and the second switch 103 and the third switch 104 are controlled to be switched off, namely when the first switch 102 and the fourth switch 105 are controlled to be switched on, the second switch 103 and the third switch 104 are controlled to be switched; when the first switch 102 and the fourth switch 105 are controlled to be turned off, the second switch 103 and the third switch 104 are controlled to be turned on. The specific process of the alternate conduction is the same as the process of the alternate conduction of the full bridge circuit using the LLC resonant circuit 109b in the prior art, and the description of the present invention is omitted here.

It should be noted that, theoretically, the value of the duty ratio d is usually 0.5, and in an actual circuit, in order to avoid that the first switch 102, the second switch 103, the third switch 104 and the fourth switch 105 are turned on or turned off simultaneously, the control circuit 111 controls the second switch 103 and the third switch 104 to be turned on after a dead time when controlling the first switch 102 and the fourth switch 105 to be turned off; when the first switch 102 and the fourth switch 105 are controlled to be turned off, the second switch 103 and the third switch 104 are controlled to be turned on after a dead time, so that the value of the duty ratio d is slightly smaller than 0.5.

It should be noted that, in a case where the voltage regulating rectification circuit 109 includes the transformer 109a, or in a case where the voltage regulating rectification circuit 109 includes the LLC resonant circuit 109b, when the control circuit 111 receives only the input current of the switch circuit, or the output current of the switch circuit, or when the control circuit 111 receives the input voltage and the output voltage of the switch circuit, and also receives the input current of the switch circuit, or the output current of the switch circuit, a specific process is similar to that when the control circuit 111 determines that the dc gain is greater than the first preset value, a process when the control circuit 111 determines that the dc gain is greater than the first preset value may be referred to, and the present invention is not repeated herein.

It should be noted that, in the case that the voltage regulating and rectifying circuit 109 includes the transformer 109a, the preset position of the switching circuit may further include an input end of the transformer 109a, or an output end of the transformer 109a, and the present invention is not limited thereto.

It should be noted that, in addition to the voltage regulating circuit, the voltage regulating rectifier circuit 109 according to the embodiment of the present invention further includes, as shown in fig. 9: the rectifying circuit 109c is configured to rectify the ac power output by the voltage regulating circuit and output the rectified ac power to a load, where the voltage regulating circuit in fig. 9 takes the transformer 109a as an example, and components specifically included in the rectifying circuit 109c are components included in the rectifying circuit in the prior art, which is not described herein again.

It should be noted that the selection types of the first switch 102, the second switch 103, the third switch 104, the fourth switch 105 and the fifth switch 106 are not limited in the present invention, and may be a Semiconductor device, such as a MOSFET (Metal-Oxide-Semiconductor-Field Effect Transistor); it may be a mechanical switch capable of performing automatic control, such as a relay or the like.

As shown in fig. 10, which is an example of a switch circuit according to an embodiment of the present invention, wherein the first switch 102, the second switch 103, the third switch 104, the fourth switch 105, and the fifth switch 106 all use NMOS (N-Metal-Oxide-Semiconductor-Field Effect Transistor), the voltage-regulating rectification circuit 109 includes a transformer 109a and a rectification circuit shown in fig. 9, and a specific operation principle is similar to the above description, and is not repeated herein.

The embodiment of the invention provides a switching circuit, which is applied to a switching power supply and comprises: the power supply, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the first capacitor, the second capacitor and the voltage-regulating rectification circuit, wherein under the condition that the fifth switch is conducted and the first switch and the second switch are disconnected, the switching power supply can work in a half-bridge mode at the moment as only the third switch and the fourth switch are arranged; under the condition that the fifth switch is disconnected, the switching power supply further comprises a first switch, a second switch, a third switch and a fourth switch, and the switching power supply can work in a full-bridge mode at the moment. Therefore, the switching power supply provided by the invention can work in a full-bridge mode and also can work in a half-bridge mode, so that the compatibility of the switching power supply is improved. Furthermore, under the condition that the voltage regulating and rectifying circuit comprises a transformer, when the switching circuit works in a half-bridge mode, the direct current gain of the switching circuit is reduced, so that in order to obtain the required direct current gain, the duty ratio needs to be adjusted to be twice of that in a full-bridge mode, and the filter inductor connected with the secondary winding of the transformer can select an inductor with smaller inductance, so that the power loss of the filter inductor is reduced, and the conversion efficiency of the switching power supply is improved; when the voltage regulating and rectifying circuit comprises the LLC resonant circuit, the working frequency of the third switch and the fourth switch needs to be reduced to obtain the required dc gain, so that the working frequency of the third switch and the fourth switch approaches the resonant frequency, thereby improving the conversion efficiency of the switching power supply.

An embodiment of the present invention provides a method for controlling a switch circuit, which is applied to the switch circuit described in the foregoing embodiment, as shown in fig. 11, and includes:

1101. and turning on the fifth switch 106, turning off the first switch 102 and the second switch 103, and controlling the switching power supply to operate in a half-bridge mode.

Alternatively, the fifth switch 106 is turned off, and the switching power supply is controlled to operate in the full-bridge mode.

The embodiment of the present invention provides a method for controlling a switch circuit, which is applied to the switch circuit described in the above embodiment, and when a fifth switch is turned on and a first switch and a second switch are turned off, because only a third switch and a fourth switch are provided, the switch power supply can be controlled to operate in a half-bridge mode at this time; under the condition that the fifth switch is disconnected, the switching power supply further comprises a first switch, a second switch, a third switch and a fourth switch, and the switching power supply can be controlled to work in a full-bridge mode at the moment. Therefore, the switching power supply can work in a full-bridge mode and can also work in a half-bridge mode, and therefore compatibility of the switching power supply is improved.

Further, before step 1101, as shown in fig. 12, a step 1100 is further included.

1100. The method comprises the steps of obtaining the voltage at two ends of a power supply 101 and the voltage output by a voltage regulating and rectifying circuit 109, and determining the direct current gain of the switch circuit according to the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109.

And/or obtaining the current at the preset position of the switch circuit.

The preset position of the switch circuit comprises the power supply 101 end or the output end of the voltage regulating rectification circuit 109.

Correspondingly, after step 1100 is executed, step 1110 specifically includes:

and under the condition that the direct current gain of the switching circuit is determined to be smaller than a first preset value and/or the current at the preset position of the switching circuit is determined to be smaller than a second preset value, the fifth switch 106 is turned on, the first switch 102 and the second switch 103 are turned off, and the switching power supply is controlled to work in a half-bridge mode.

And when the direct current gain of the switch circuit is determined to be greater than the first preset value and/or the current at the preset position of the switch circuit is determined to be greater than the second preset value, turning off the fifth switch 106 and controlling the switch power supply to work in a full-bridge mode.

Further, in the method for controlling the switching circuit according to the embodiment of the present invention, when the voltage regulation and rectification circuit includes a transformer, since the dc gain of the switching circuit is reduced when the switching circuit operates in the half-bridge mode, in order to obtain the required dc gain, the duty ratio needs to be adjusted to be twice that in the full-bridge mode, so that the filter inductor connected to the secondary winding of the transformer can select an inductor with a smaller inductance, thereby reducing the power loss of the filter inductor and improving the conversion efficiency of the switching power supply; when the voltage regulating and rectifying circuit comprises the LLC resonant circuit, the working frequency of the third switch and the fourth switch needs to be reduced to obtain the required dc gain, so that the working frequency of the third switch and the fourth switch approaches the resonant frequency, thereby improving the conversion efficiency of the switching power supply.

An embodiment of the present invention provides a method for controlling a switching circuit, which is applied to a switching power supply including the switching circuit, as shown in fig. 13, where the switching circuit includes: the power supply 101 comprises a first bridge arm a, a second bridge arm b, a fifth capacitor 113 and a voltage-regulating rectifying circuit 109, wherein the first bridge arm a, the second bridge arm b and the fifth capacitor 113 are connected with the power supply in parallel; the first bridge arm a comprises a first switch 102 and a second switch 103 which are connected in series; the second bridge arm b comprises a third switch 104 and a fourth switch 105 which are connected in series; a first input end of the voltage regulating rectifying circuit 109 is connected between the first switch 102 and the second switch 103, and a second input end of the voltage regulating rectifying circuit 109 is connected between the third switch 104 and the fourth switch 105.

The specific method, as shown in fig. 14, includes:

1401. and controlling the switching power supply to work in a full-bridge mode.

Or, the third switch 104 is turned off, the fourth switch 105 is turned on, and the switching power supply is controlled to operate in a half-bridge mode.

Specifically, since the switch circuit shown in fig. 13 is a full-bridge circuit in the prior art, the control circuit can control the switch power supply to operate in the full-bridge mode according to a method for controlling the full-bridge circuit in the prior art, which can specifically refer to the method for controlling the full-bridge circuit in the prior art, and the details of the present invention are not repeated herein.

Or, the control circuit turns off the third switch 104 and turns on the fourth switch 105, then the switches in the switch circuit shown in fig. 13 are equivalent and only have the first switch 102 and the second switch 103, at this time, the control circuit controls the first switch 102 and the second switch 103 according to the alternating on mode of the duty ratio a and the frequency f1, that is, when the first switch 102 is controlled to be on, the second switch 103 is controlled to be off; when the first switch 102 is controlled to be off, the second switch 103 is controlled to be on. The switching power supply operates in a half-bridge mode.

It should be noted that the value of the duty ratio a is usually less than 0.5, and the time interval for the control circuit to control the first switch 102 and the second switch 103 to conduct alternately is 0.5-a.

Note that the control circuit that controls the switch circuit shown in fig. 13 is different from the control circuit 111 in fig. 5 described above.

The embodiment of the invention provides a method for controlling a switch circuit, which is applied to a switch power supply comprising the switch circuit, and under the condition that a third switch is disconnected and a fourth switch is connected, the switch power supply can be controlled to work in a half-bridge mode at the moment as only a first switch and a second switch are arranged; when the first switch, the second switch, the third switch and the fourth switch are all involved in working, the switching power supply can be controlled to work in a full-bridge mode, so that the switching power supply can work in the full-bridge mode and can also work in a half-bridge mode, and therefore the compatibility of the switching power supply is improved.

Further, before step 1401, as shown in fig. 15, step 1400 is further included.

1400. The method comprises the steps of obtaining the voltage at two ends of a power supply 101 and the voltage output by a voltage regulating and rectifying circuit 109, and determining the direct current gain of the switch circuit according to the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109. And/or obtaining the current at the preset position of the switch circuit.

The preset position of the switch circuit comprises the power supply end or the output end of the voltage regulating and rectifying circuit.

Correspondingly, after step 1400 is executed, step 1401 specifically includes:

and when the direct current gain of the switch circuit is determined to be smaller than the first preset value and/or the current at the preset position of the switch circuit is determined to be smaller than the second preset value, the third switch 104 is turned off, the fourth switch 105 is turned on, and the switch power supply is controlled to work in a half-bridge mode.

That is, in the case where the voltage regulating and rectifying circuit 109 includes the transformer 109a, when the control circuit receives only the voltage across the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage across the power supply 101 is obtained to obtain the dc gain of the switching circuit, and the obtained dc gain is compared with the first preset value stored in advance, and when the control circuit determines that the obtained dc gain is smaller than the first preset value, the control circuit controls the third switch 104 to be turned off, controls the fourth switch 105 to be turned on, and controls the first switch 102 and the second switch 103 according to the alternately-on pulse signal having the duty ratio of a and the frequency of f1, that is, controls the second switch 103 to be turned off when the first switch 102 is controlled to be turned on, according to the voltage output by the voltage regulating and rectifying circuit 109 and the voltage across the power supply 101; when the first switch 102 is controlled to be off, the second switch 103 is controlled to be on. The specific process of alternating conduction is as follows: when the first switch 102 is turned on and the second switch 103 is turned off, the power supply 101 charges the fifth capacitor 113 by passing the output dc current through the first switch 102, the primary winding of the transformer 109a, and the fifth capacitor 113 in this order, and the direction of the current flowing into the primary winding of the transformer 109a is from the negative electrode to the positive electrode of the power supply 101 with respect to the power supply 101; when the first switch 102 is turned off and the second switch 103 is turned on, the fifth capacitor 113 serves as a power supply and outputs a direct current sequentially through the primary winding of the transformer 109a, and the second switch 103 causes the current flowing through the primary winding of the transformer 109a to flow in a direction from the positive pole to the negative pole of the power supply 101 with respect to the power supply 101, so that an alternating current is generated in the primary winding of the transformer 109a, and the alternating current is transformed by the transformer 109a and then output from the secondary winding of the transformer 109 a.

Under the condition that the voltage regulating and rectifying circuit 109 comprises the LLC resonant circuit 109b, when the control circuit only receives the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage at two ends of the power supply 101 is obtained, the direct current gain of the switching circuit is obtained, the obtained direct current gain is compared with a first preset value stored in advance, when the obtained direct current gain is determined to be smaller than the first preset value, the control circuit controls the third switch 104 to be switched off, controls the fourth switch 105 to be switched on, and controls the first switch 102 and the second switch 103 according to the alternately-on pulse signal with the duty ratio of b and the frequency of f2 according to the voltage output by the voltage regulating and rectifying circuit 109 and the voltage at two ends of the power supply 101, namely controls the second switch 103 to be switched off when the first switch; when the first switch 102 is controlled to be off, the second switch 103 is controlled to be on. The specific process of alternating conduction is as follows: when the first switch 102 is turned on and the second switch 103 is turned off, the power supply 101 charges the fifth capacitor 113 by passing the output dc current through the first switch 102, the resonant inductor L2 of the LLC resonant circuit 109b, the fourth capacitor C1, the first inductor L1, and the fifth capacitor 113 in this order, and the direction of the current flowing into the resonant inductor L2 of the LLC resonant circuit 109b is from the negative electrode to the positive electrode of the power supply 101 with respect to the power supply 101; when the first switch 102 is turned off and the second switch 103 is turned on, the fifth capacitor 113 serves as a power supply, and the output direct current passes through the first inductor L1, the fourth capacitor C1, the resonant inductor L2, and the second switch 103 in sequence, i.e., the direction of the current flowing into the resonant inductor L2 of the LLC resonant circuit 109b is from the positive pole to the negative pole of the power supply 101 with respect to the power supply 101, so that the resonant inductor L2 of the LLC resonant circuit 109b generates and outputs an alternating current.

It should be noted that, when the voltage regulating and rectifying circuit 109 includes the transformer 109a, or when the voltage regulating and rectifying circuit 109 includes the LLC resonant circuit 109b, and when the control circuit receives only the input current of the power supply 101, or the current output by the voltage regulating and rectifying circuit 109, or when the control circuit receives the voltage across the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, and also receives the input current of the power supply 101, or the current output by the voltage regulating and rectifying circuit 109, the specific process is similar to that when the control circuit determines that the dc gain is smaller than the first preset value in the switch circuit, the process of the switch circuit can be referred to, and the description of the present invention is omitted here.

And controlling the switching power supply to work in a full-bridge mode when the direct-current gain of the switching circuit is determined to be larger than the first preset value and/or the current at the preset position of the switching circuit is determined to be larger than the second preset value.

That is, in the case where the voltage regulating and rectifying circuit 109 includes the transformer 109a, when the control circuit receives only the voltage across the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage across the power supply 101 is obtained, the dc gain of the switching circuit is obtained, the obtained dc gain is compared with the first preset value stored in advance, and when it is determined that the obtained dc gain is greater than the first preset value, the first switch 102 and the fourth switch 105, the second switch 103 and the third switch 104 are controlled according to the pulse signal with the duty ratio of c and the frequency of f3 that are alternately turned on, that is, when the first switch 102 and the fourth switch 105 are controlled to be turned on, the second switch 103 and the third switch 104 are controlled to be turned off; when the first switch 102 and the fourth switch 105 are controlled to be turned off, the second switch 103 and the third switch 104 are controlled to be turned on. The specific process of the alternate conduction is the same as the process of the alternate conduction of the full bridge circuit using the transformer 109a in the prior art, and the description of the present invention is omitted here.

Under the condition that the voltage regulating and rectifying circuit 109 comprises the LLC resonant circuit 109b, when the control circuit only receives the voltage at two ends of the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, the ratio of the voltage output by the voltage regulating and rectifying circuit 109 to the voltage at two ends of the power supply 101 is obtained, the direct current gain of the switching circuit is obtained, the obtained direct current gain is compared with a first preset value stored in advance, when the obtained direct current gain is determined to be greater than the first preset value, the first switch 102 and the fourth switch 105, the second switch 103 and the third switch 104 are controlled according to the pulse signal with the duty ratio of d and the frequency of f4, wherein when the first switch 102 and the fourth switch 105 are controlled to be switched on, the second switch 103 and the third switch 104 are controlled to be switched off; when the first switch 102 and the fourth switch 105 are controlled to be turned off, the second switch 103 and the third switch 104 are controlled to be turned on. The specific process of the alternate conduction is the same as the process of the alternate conduction of the full bridge circuit using the LLC resonant circuit 109b in the prior art, and the description of the present invention is omitted here.

It should be noted that, when the voltage regulating and rectifying circuit 109 includes the transformer 109a, or when the voltage regulating and rectifying circuit 109 includes the LLC resonant circuit 109b, and when the control circuit receives only the input current of the power supply 101, or the current output by the voltage regulating and rectifying circuit 109, or when the control circuit receives the voltage across the power supply 101 and the voltage output by the voltage regulating and rectifying circuit 109, and also receives the input current of the power supply 101, or the current output by the voltage regulating and rectifying circuit 109, the specific process is similar to that when the control circuit determines that the dc gain is greater than the first preset value in the switch circuit, and the process of the switch circuit can be referred to, which is not described herein again.

The embodiment of the invention provides a method for controlling a switch circuit, which is applied to a switch power supply comprising the switch circuit, and under the condition that a third switch is disconnected and a fourth switch is connected, the switch power supply can be controlled to work in a half-bridge mode at the moment as only a first switch and a second switch are arranged; when the first switch, the second switch, the third switch and the fourth switch are all involved in working, the switching power supply can be controlled to work in a full-bridge mode, so that the switching power supply can work in the full-bridge mode and can also work in a half-bridge mode, and therefore the compatibility of the switching power supply is improved. Furthermore, under the condition that the voltage regulating and rectifying circuit comprises a transformer, when the switching circuit works in a half-bridge mode, the direct current gain of the switching circuit is reduced, so that in order to obtain the required direct current gain, the duty ratio needs to be adjusted to be twice of that in a full-bridge mode, and the filter inductor connected with the secondary winding of the transformer can select an inductor with smaller inductance, so that the power loss of the filter inductor is reduced, and the conversion efficiency of the switching power supply is improved; under the condition that the voltage regulating rectification circuit comprises the LLC resonant circuit, the working frequency of the first switch and the second switch needs to be reduced to obtain the required direct current gain, so that the working frequency of the first switch and the second switch is closer to the resonant frequency, and the conversion efficiency of the switching power supply is improved.

An embodiment of the present invention provides a switching power supply, as shown in fig. 16, including: a filter circuit 1601 and the switch circuit 1602 described in the above embodiments.

The switch circuit 1602 is connected to the filter circuit 1601.

The filtering circuit 1601 is configured to filter a voltage output by the switching circuit 1602.

It should be noted that the filter circuit 1601 is any one of filter circuits in the prior art, and the present invention is not described herein again.

The embodiment of the invention provides a switching power supply, which comprises a filter circuit and a switching circuit, wherein the switching circuit comprises a power supply, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a first capacitor, a second capacitor and a voltage-regulating rectification circuit; under the condition that the fifth switch is disconnected, the switching power supply further comprises a first switch, a second switch, a third switch and a fourth switch, and the switching power supply can work in a full-bridge mode at the moment. Therefore, the switching power supply provided by the invention can work in a full-bridge mode and also can work in a half-bridge mode, so that the compatibility of the switching power supply is improved.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be physically included alone, or two or more units may be integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.

The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute some steps of the methods according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A switching circuit, applied to a switching power supply, includes:

a power source;

the first bridge arm, the second bridge arm and the capacitor branch are connected in parallel at two ends of the power supply; the first bridge arm comprises a first switch and a second switch which are connected in series, the second bridge arm comprises a third switch and a fourth switch which are connected in series, and the capacitor branch comprises a first capacitor and a second capacitor which are connected in series;

a fifth switch; one end of the fifth switch is connected between the first capacitor and the second capacitor, and the other end of the fifth switch is connected between the first switch and the second switch;

a voltage regulating rectification circuit; the first input end of the voltage-regulating rectification circuit is connected between the first switch and the second switch, and the second input end of the voltage-regulating rectification circuit is connected between the third switch and the fourth switch;

the switching power supply operates in a half-bridge mode under the condition that the fifth switch is turned on and the first switch and the second switch are turned off; when the fifth switch is turned off, the switching power supply operates in a full-bridge mode;

a control circuit;

the control circuit is respectively connected with the first switch, the second switch, the third switch, the fourth switch and the fifth switch;

the control circuit is configured to turn on the fifth switch, turn off the first switch and the second switch, and control the switching power supply to operate in a half-bridge mode;

the control circuit is further configured to disconnect the fifth switch and control the switching power supply to operate in a full-bridge mode;

the control circuit is also used for acquiring the voltage at the two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit, and determining the direct current gain of the switch circuit according to the voltage at the two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit; the current acquisition circuit is also used for acquiring the current at a preset position of the switching circuit; the preset position of the switch circuit comprises the power supply end or the output end of the voltage-regulating rectifying circuit;

the control circuit is further configured to, when it is determined that the dc gain of the switching circuit is smaller than a first preset value and/or the current at a preset position of the switching circuit is smaller than a second preset value, turn on the fifth switch, turn off the first switch and the second switch, and control the switching power supply to operate in a half-bridge mode;

under the condition that the direct current gain of the switch circuit is determined to be larger than the first preset value and/or the current at the preset position of the switch circuit is determined to be larger than the second preset value, the fifth switch is switched off, and the switch power supply is controlled to work in a full-bridge mode;

the second preset value is a fixed value corresponding to the current at the preset position of the switch circuit; when the control circuit judges according to the direct current gain of the switch circuit, the first preset value is a fixed value; when the control circuit judges according to the direct current gain of the switch circuit and the current at the preset position of the switch circuit, the first preset value is a change value.

2. The switching circuit of claim 1, further comprising: a third capacitor;

and the third capacitor is connected in series with a line connecting the first input end of the voltage-regulating rectification circuit and the third switch.

3. The switching circuit according to any one of claims 1 to 2, wherein the voltage regulating and rectifying circuit comprises: a transformer.

4. The switching circuit according to any one of claims 1 to 2, wherein the voltage regulating and rectifying circuit comprises: LLC resonant circuit.

5. A method for controlling a switching circuit, applied to the switching circuit according to any one of claims 1 to 4, comprising:

switching on the fifth switch, switching off the first switch and the second switch, and controlling the switching power supply to work in a half-bridge mode; or,

disconnecting the fifth switch and controlling the switching power supply to work in a full-bridge mode;

before the fifth switch is turned on or before the fifth switch is turned off, the method further includes:

acquiring the voltage at two ends of a power supply and the voltage output by a voltage regulating and rectifying circuit, and determining the direct current gain of the switch circuit according to the voltage at two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit; and/or the presence of a gas in the gas,

obtaining current at a preset position of the switching circuit; the preset position of the switch circuit comprises the power supply end or the output end of the voltage-regulating rectifying circuit;

the turning on the fifth switch, turning off the first switch and the second switch, and controlling the switching power supply to operate in the half-bridge mode includes:

under the condition that the direct current gain of the switching circuit is determined to be smaller than a first preset value and/or the current at a preset position of the switching circuit is determined to be smaller than a second preset value, the fifth switch is turned on, the first switch and the second switch are turned off, and the switching power supply is controlled to work in a half-bridge mode;

the turning off the fifth switch and controlling the switching power supply to operate in a full-bridge mode includes:

when the direct current gain of the switch circuit is determined to be larger than the first preset value and/or the current at the preset position of the switch circuit is determined to be larger than the second preset value, the fifth switch is switched off, and the switch power supply is controlled to work in a full-bridge mode;

6. A method of controlling a switching circuit, for use in a switching power supply including a switching circuit, the switching circuit comprising: the power supply, a first bridge arm, a second bridge arm, a third capacitor and a voltage-regulating rectifying circuit are connected with the power supply in parallel; the first bridge arm comprises a first switch and a second switch which are connected in series; the second bridge arm comprises a third switch and a fourth switch which are connected in series; the first input end of the voltage-regulating rectification circuit is connected between the first switch and the second switch, and the second input end of the voltage-regulating rectification circuit is connected between the third switch and the fourth switch; characterized in that the method comprises:

controlling the switching power supply to work in a full-bridge mode; or,

turning off the third switch, turning on the fourth switch, and controlling the switching power supply to work in a half-bridge mode;

before the controlling the switching power supply to operate in the full-bridge mode, or before the turning off the third switch, further comprising:

acquiring the voltage at two ends of a power supply and the voltage output by a voltage regulating and rectifying circuit, and determining the direct current gain of the switch circuit according to the voltage at two ends of the power supply and the voltage output by the voltage regulating and rectifying circuit; and/or, obtaining a current at a preset position of the switching circuit; the preset position of the switch circuit comprises the power supply end or the output end of the voltage-regulating rectifying circuit;

the turning off the third switch, turning on the fourth switch, and controlling the switching power supply to operate in the half-bridge mode includes:

when the direct current gain of the switch circuit is determined to be smaller than a first preset value and/or the current at a preset position of the switch circuit is determined to be smaller than a second preset value, the third switch is turned off, the fourth switch is turned on, and the switch power supply is controlled to work in a half-bridge mode;

the controlling the switching power supply to work in a full-bridge mode comprises:

when the direct current gain of the switch circuit is determined to be larger than the first preset value and/or the current at the preset position of the switch circuit is determined to be larger than the second preset value, controlling the switch power supply to work in a full-bridge mode;

7. A switching power supply, comprising: a filter circuit and the switching circuit of any one of claims 1-4;

the switch circuit is connected with the filter circuit;

and the filter circuit is used for filtering the voltage output by the switch circuit.