CN115842467A - Switch converter, AC-DC conversion circuit and control method - Google Patents
Switch converter, AC-DC conversion circuit and control method Download PDFInfo
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- CN115842467A CN115842467A CN202210986303.XA CN202210986303A CN115842467A CN 115842467 A CN115842467 A CN 115842467A CN 202210986303 A CN202210986303 A CN 202210986303A CN 115842467 A CN115842467 A CN 115842467A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
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Abstract
The invention provides a switch converter, an AC-DC conversion circuit and a control method, wherein a capacitance switch control circuit detects the voltage on a bus, and when the voltage on the bus is smaller than the bus voltage threshold value, the capacitance switch control circuit controls the conduction of a capacitance switch, so that a second bus capacitor is connected to a charge-discharge loop of the bus; when the voltage on the bus is larger than or equal to the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be switched off, so that the second bus capacitor is not connected to the charge-discharge loop of the bus. The invention can reduce harmonic wave and power consumption.
Description
Technical Field
The invention relates to the field of power supplies, in particular to a switching converter, an AC-DC conversion circuit and a control method.
Background
Currently, AC-DC conversion circuits are widely used in switching converters in various electronic devices. In the AC-DC conversion circuit, first, an alternating current voltage needs to be rectified into a direct current voltage by a rectifying circuit and output to a bus, and then, a DC-DC conversion unit converts a voltage on the bus into a desired target voltage.
The operating principle of the AC-DC conversion circuit determines that harmonics are easily generated on an AC circuit connected thereto, and in order to reduce the harmonics, chinese patent document CN 201490878U discloses a novel input current harmonic suppression circuit for a switching converter to suppress the harmonics, but the scheme is relatively complicated.
Disclosure of Invention
Research shows that many people move around the world by using the same switching converter, the alternating-current voltage of a power grid in each region is different, and harmonic waves caused by the same switching converter in the power grid under the input of the alternating-current voltages with different magnitudes are also different. In view of the above-mentioned situation, a main object of the present invention is to provide a switching converter, an AC-DC conversion circuit, and a control method, which can adaptively reduce both harmonic waves and power consumption in various regions with different AC voltages of a power grid.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
an AC-DC conversion circuit comprises a rectification circuit, a first bus capacitor and a DC-DC conversion unit, wherein the rectification circuit is used for rectifying input alternating-current voltage to obtain direct-current voltage and supplying the direct-current voltage to a bus, one end of the first bus capacitor is connected with the bus, the other end of the first bus capacitor is connected with the ground, the DC-DC conversion unit is used for converting the voltage on the bus into output target voltage, and the AC-DC conversion circuit further comprises a second bus capacitor, a capacitor switch and a capacitor switch control circuit; the second bus capacitor and the capacitor switch are connected in series between the bus and the ground; (ii) a The capacitance switch control circuit detects the voltage on the bus, and when the voltage on the bus is smaller than a bus voltage threshold value, the capacitance switch control circuit controls the capacitor switch to be conducted, so that the second bus capacitor is connected to a charge-discharge loop of the bus; when the voltage on the bus is larger than or equal to the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be switched off, so that the second bus capacitor is not connected to the charge-discharge loop of the bus.
Preferably, the capacitance switch control circuit comprises a first resistance voltage division circuit, a driving switch tube and a pull-up resistor; the first resistance voltage division circuit comprises a first voltage division resistor and a second voltage division resistor, the first voltage division resistor and the second voltage division resistor are connected between the bus and the ground in series, a common end of the first voltage division resistor and the second voltage division resistor is connected with a control end of the driving switch tube, the control end of the driving switch tube is grounded through the second voltage division resistor, a current inflow end of the driving switch tube is connected with the control end of the capacitance switch, a current outflow end of the driving switch tube is connected with the ground, and the control end of the capacitance switch is connected with a first voltage through the pull-up resistor; and satisfies the following conditions: vin0= Vth1 (R1 + R2)/R2, VCC > Vth2; vin0 is the bus voltage threshold, vth1 is the start voltage of the driving switch tube, vth2 is the start voltage of the capacitor switch, VCC is the magnitude of the first voltage, and R1 and R2 are the resistance value of the first divider resistor and the resistance value of the second divider resistor, respectively.
Preferably, the capacitance switch control circuit comprises a first resistance voltage division circuit, a driving switch tube and a second resistance voltage division circuit; the first resistance voltage division circuit comprises a first voltage division resistor and a second voltage division resistor, the first voltage division resistor and the second voltage division resistor are connected between the bus and the ground in series, the common end of the first voltage division resistor and the second voltage division resistor is connected with the control end of the driving switch tube, and the control end of the driving switch tube is grounded through the second voltage division resistor; the second resistance voltage division circuit comprises a third voltage division resistor and a fourth voltage division resistor, the third voltage division resistor and the fourth voltage division resistor are connected between a first voltage and the ground in series, a common end of the third voltage division resistor and a common end of the fourth voltage division resistor are connected with a control end of the capacitive switch, and the control end of the capacitive switch is grounded through the fourth voltage division resistor; the current inflow end of the driving switch tube is connected with the control end of the capacitance switch, and the current outflow end of the driving switch tube is connected with the ground; and satisfies the following conditions: vin0= Vth1 (R1 + R2)/R2, VCC R4/(R3 + R4) > Vth2; vin0 is the bus voltage threshold, vth1 is the start voltage of the driving switch tube, vth2 is the start voltage of the capacitor switch, VCC is the magnitude of the first voltage, and R1, R2, R3, and R4 are the resistance value of the first voltage dividing resistor, the resistance value of the second voltage dividing resistor, the resistance value of the third voltage dividing resistor, and the resistance value of the fourth voltage dividing resistor, respectively.
Preferably, the AC-DC conversion circuit further includes a stabilizing capacitor for preventing the second bus capacitor from being frequently connected to and disconnected from the charge-discharge loop of the bus, one end of the stabilizing capacitor is connected to the control end of the driving switch tube, and the other end of the stabilizing capacitor is grounded.
Preferably, the capacity of the second bus capacitor is greater than the capacity of the first bus capacitor.
Preferably, the DC-DC conversion unit is a flyback DC-DC conversion unit.
Preferably, the bus bar is grounded through the second bus bar capacitor and the capacitor switch in sequence.
The invention also provides a switching converter comprising any one of the AC-DC conversion circuits.
The invention also provides a control method of the AC-DC conversion circuit, wherein the capacitance switch control circuit detects the voltage on the bus; when the voltage on the bus is smaller than the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be conducted, so that the second bus capacitor is connected to a charge-discharge loop of the bus; when the voltage on the bus is larger than or equal to the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be switched off, so that the second bus capacitor is not connected to the charge-discharge loop of the bus.
Preferably, when the voltage on the bus is less than Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be turned off, and the voltage of the control terminal of the capacitive switch is pulled up to the first voltage, so that the capacitive switch is controlled to be turned on; when the voltage on the bus is greater than or equal to Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be on, the voltage of the control end of the capacitive switch is pulled down to zero, and the capacitive switch is controlled to be off.
Preferably, when the voltage on the bus is less than Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be turned off, and the voltage of the control terminal of the capacitive switch is maintained at the voltage of the fourth voltage dividing resistor, so that the capacitive switch is controlled to be turned on; when the voltage on the bus is greater than or equal to Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be on, the voltage of the control end of the capacitive switch is pulled down to zero, and the capacitive switch is controlled to be off.
[ PROBLEMS ] the present invention
When the voltage on the bus is smaller than the bus voltage threshold (namely the current accessed alternating voltage is smaller), the second bus capacitor is accessed to the charge-discharge loop of the bus by controlling the conduction of the capacitor switch, the second bus capacitor can also provide a part of discharge current, the first bus capacitor and the second bus capacitor only need to be charged and discharged with smaller amplitude on the whole, the ripple on the bus is relatively smaller, and the harmonic in the alternating current circuit connected with the rectifying circuit is less. When the voltage on the bus is greater than the bus voltage threshold (i.e. the currently accessed alternating voltage is greater), at this time, because the voltage on the bus is greater, in order to meet the output power requirement of the output end and maintain the requirement of the target voltage, only the bus capacitor is needed to provide a smaller discharging current, and the discharging current provided by the first bus capacitor does not cause a larger ripple on the bus, so that the second bus capacitor is not accessed to the charging and discharging loop of the bus by controlling the capacitor switch to be disconnected, thereby avoiding more devices such as the second bus capacitor and the capacitor switch to be accessed to the bus to cause more power consumption, and simultaneously, the ripple caused in the alternating current circuit because the bus ripple is smaller. The scheme can adaptively realize the reduction of harmonic waves and the reduction of power consumption in all areas with different alternating-current voltages by using a simple circuit structure.
Other advantages of the present invention will be described in the detailed description, and those skilled in the art will understand the technical features and technical solutions presented in the description.
Drawings
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the figure:
FIG. 1 is a schematic diagram of an AC-DC converter circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an AC-DC converter circuit according to another embodiment of the present invention.
Detailed Description
The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in order to avoid obscuring the nature of the present invention, well-known methods, procedures, and components have not been described in detail.
Furthermore, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.
Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including but not limited to".
In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
Fig. 1 is an AC-DC conversion circuit according to an embodiment of the present invention, which includes a rectification circuit, a first bus capacitor C1, a second bus capacitor C2, a capacitor switch Q1, a capacitor switch control circuit, and a DC-DC conversion unit.
The input end of the rectifying circuit is used for inputting alternating-current voltage, and the rectifying circuit is used for rectifying the input alternating-current voltage to obtain direct-current voltage and supplying the direct-current voltage to the bus. The rectifying circuit may be a full-bridge rectifying circuit or a half-bridge rectifying circuit.
The input end of the DC-DC conversion unit inputs the voltage on the bus, and the DC-DC conversion unit is used to convert the voltage on the bus into an output target voltage, specifically, the DC-DC conversion unit is controlled to convert the voltage on the bus into the output target voltage, which can be set according to appropriate requirements, and for common consumer electronics, 5V, 12V, 24V, and the like are relatively common target voltages. The DC-DC conversion unit may be of various types, for example, may be an isolated type, i.e., a conversion unit with a transformer, such as a flyback conversion unit and a forward conversion unit, or may be a non-isolated type, e.g., a bulk circuit. The DC-DC conversion unit shown in fig. 1 belongs to an isolated flyback conversion unit, and includes a switching tube Q3, a transformer T, a rectifier diode D1 and a filter capacitor C4, a first end of a primary coil of the transformer T is connected to a bus, a second end is grounded through the switching tube Q3, a first end of a secondary coil of the transformer T is connected to an anode of the rectifier diode D1, two ends of the filter capacitor C4 are respectively connected to a cathode of the rectifier diode D1 and a second end of the secondary coil of the transformer T, a cathode end of the rectifier diode D1 is used as an output terminal Vout of the DC-DC conversion unit, that is, an output terminal Vout of an AC-DC conversion circuit, the output terminal Vout outputs a target voltage, and the voltage of the output terminal Vout can be stabilized at a set target voltage by adjusting a duty ratio of a control signal PWM of the switching tube Q3.
One end of a first bus capacitor C1 is connected with a bus, the other end of the first bus capacitor C1 is connected with the ground, a second bus capacitor C2 and a capacitor switch Q1 are connected between the bus and the ground in series, a capacitor switch control circuit detects the voltage on the bus, and when the voltage on the bus is smaller than a bus voltage threshold value, the capacitor switch control circuit controls the capacitor switch Q1 to be conducted, so that the second bus capacitor C2 is connected to a charge-discharge loop of the bus; when the voltage on the bus is greater than or equal to the bus voltage threshold, the capacitance switch control circuit controls the capacitance switch Q1 to be switched off, so that the second bus capacitor C2 is not connected to the charge-discharge loop of the bus. In some embodiments, the capacitive switch Q1 may be a MOS transistor, such as an N-channel MOS transistor.
Because the ac voltages of different areas and power grids are different, some of the ac voltages are different, for example, the ac voltage in china is 220V, while the ac voltage in the united states is 110V, which is different by one time, the voltages rectified and output by the rectifier circuit are also different, that is, the voltages on the bus voltages are different. When the output power requirement of the output end Vout is fixed, when the voltage on the bus is smaller than the bus voltage threshold (that is, the currently accessed alternating current voltage is smaller), at this time, since the voltage on the bus is smaller, in order to meet the output power requirement of the output end Vout, the bus capacitor is required to provide a larger discharge current, if only the first bus capacitor C1 provides the discharge current, the first bus capacitor C1 is caused to perform large-amplitude charging and discharging, so that a ripple wave appearing on the bus is large, further more harmonic waves appear in an alternating current circuit connected with the rectifying circuit, and the evaluation of the electromagnetic compatibility of the electronic device including the AC-DC conversion circuit can be reduced. Therefore, in order to reduce such an influence, when the voltage on the bus is smaller than the bus voltage threshold, the capacitor switch Q1 is controlled to be turned on to connect the second bus capacitor C2 to the bus charge-discharge circuit, and the second bus capacitor C2 can also provide a part of discharge current, so that the first bus capacitor C1 and the second bus capacitor C2 need only to be charged and discharged with a small amplitude as a whole, the ripple on the bus is relatively small, and the harmonics in the ac circuit connected to the rectifier circuit are less. When the voltage on the bus is greater than the bus voltage threshold (i.e., the currently accessed ac voltage is greater), at this time, because the voltage on the bus is greater, in order to meet the output power requirement of the output terminal Vout and maintain the requirement at the target voltage, only the bus capacitor C1 is needed to provide a smaller discharging current, and the discharging current provided by the first bus capacitor C1 does not cause a larger ripple on the bus, so that the second bus capacitor C2 is not accessed into the charging and discharging loop of the bus by controlling the capacitor switch Q1 to be switched off, thereby avoiding more devices such as the second bus capacitor C2 and the capacitor switch Q1 from being accessed into the bus to cause more power consumption, and simultaneously, the ripple caused in the ac circuit due to the smaller bus ripple can be smaller.
In summary, the capacitance switch control circuit respectively controls the second bus capacitor C2 to be connected to or not to be connected to the charge-discharge circuit of the bus under different conditions according to the magnitude relationship between the voltage on the bus and the bus voltage threshold, and can adaptively realize the reduction of the harmonic wave and the reduction of the power consumption in various regions with different ac voltages.
In addition, in some embodiments, the bus passes through second bus capacitor C2 and capacitor switch Q1 in order to be grounded, at this moment, because capacitor switch Q1 is connected with the bus through second bus capacitor C2, namely not directly connected with the bus, it directly adds on capacitor switch Q1 to have avoided the high pressure on the bus, therefore, capacitor switch Q1 can not be punctured by the high pressure of bus, from other angles, capacitor switch Q1 can choose for use withstand voltage less device to can save cost.
In some embodiments, the capacitive switch control circuit includes a first resistive voltage divider circuit, a driving switch Q2 (for example, a MOS transistor such as an N-channel MOS transistor), and a second resistive voltage divider circuit; the first resistor voltage division circuit comprises a first voltage division resistor R1 and a second voltage division resistor R2, the first voltage division resistor R1 and the second voltage division resistor R2 are connected between a bus and the ground in series, the common end of the first voltage division resistor R1 and the second voltage division resistor R2 is connected with the control end of the driving switch tube Q2, and the control end of the driving switch tube Q2 is grounded through the second voltage division resistor R2; the second resistor voltage division circuit comprises a third voltage division resistor R3 and a fourth voltage division resistor R4, the third voltage division resistor R3 and the fourth voltage division resistor R4 are connected between the first voltage and the ground in series, the common end of the third voltage division resistor R3 and the fourth voltage division resistor R4 is connected with the control end of the capacitor switch Q1, and the control end of the capacitor switch Q1 is grounded through the fourth voltage division resistor R4; the current inflow end of the driving switch tube Q2 is connected with the control end of the capacitance switch Q1, and the current outflow end is connected with the ground; and satisfies the following conditions: vin0= Vth1 (R1 + R2)/R2, VCC R4/(R3 + R4) > Vth2; vin0 is a bus voltage threshold, vth1 is a start voltage of the driving switch transistor Q2, vth2 is a start voltage of the capacitor switch Q1, VCC is a first voltage, and R1, R2, R3, and R4 are a resistance value of the first voltage dividing resistor R1, a resistance value of the second voltage dividing resistor R2, a resistance value of the third voltage dividing resistor R3, and a resistance value of the fourth voltage dividing resistor R4, respectively. When the voltage on the bus is greater than the bus voltage threshold Vin0, the voltage on the control end of the driving switch tube Q2 (i.e. the voltage of the second voltage-dividing resistor R2) is greater than the starting voltage Vth1 of the driving switch tube Q2, the driving switch tube Q2 is controlled to be switched on, the voltage on the control end of the capacitor switch Q1 is pulled down and is less than the starting voltage Vth2 of the capacitor switch Q1, so that the capacitor switch Q1 is switched off, and the second bus capacitor C2 is not connected to the charge-discharge loop of the bus; when the voltage on the bus is smaller than the bus voltage threshold Vin0, the voltage on the control end of the driving switch tube Q2 (i.e. the voltage of the second voltage-dividing resistor R2) is smaller than the starting voltage Vth1 of the driving switch tube Q2, the driving switch tube Q2 is controlled to be turned off, the voltage on the control end of the capacitor switch Q1 is maintained to be greater than the starting voltage Vth2 of the capacitor switch Q1 by the first resistor voltage-dividing circuit, the capacitor switch Q1 is turned on, and therefore the second bus capacitor C2 is connected to the charge-discharge loop of the bus.
In some embodiments, in order to prevent the voltage on the bus from shaking to cause the driving switch tube Q2 to be frequently switched on and off, and further cause the second bus capacitor C2 to be frequently switched in and out of the charge and discharge loop of the bus, the DC-DC conversion circuit further includes a stabilizing capacitor C3 for preventing the second bus capacitor C2 from being frequently switched in and out of the charge and discharge loop of the bus, wherein one end of the stabilizing capacitor C3 is connected to the control end of the driving switch tube Q2, and the other end of the stabilizing capacitor C3 is grounded. At a certain moment, the voltage on the bus bar suddenly changes (for example, spikes), and due to the existence of the stabilizing capacitor C3, the voltage on the fourth voltage-dividing resistor R4 does not suddenly change, but starts to rise slowly, so the driving switch tube Q2 still maintains the state at the certain moment (for example, is turned on), and then the sudden change on the bus bar disappears, the voltage on the fourth voltage-dividing resistor R4 starts to recover slowly again, and the driving switch tube Q2 still maintains the state at the certain moment.
As shown in fig. 2, in some embodiments, the capacitive switch control circuit includes a first resistor divider circuit, a driving switch Q2, and a pull-up resistor R5; the first resistor voltage division circuit comprises a first voltage division resistor R1 and a second voltage division resistor R2, the first voltage division resistor R1 and the second voltage division resistor R2 are connected between a bus and the ground in series, the common end of the first voltage division resistor R1 and the second voltage division resistor R2 is connected with the control end of a driving switch tube Q2, the control end of the driving switch tube Q2 is grounded through the second voltage division resistor R2, the current inflow end of the driving switch tube Q2 is connected with the control end of a capacitor switch Q1, the current outflow end of the driving switch tube Q2 is connected with the ground, and the control end of the capacitor switch Q1 is connected with a first voltage through a pull-up resistor R5; and satisfies the following conditions: vin0= Vth1 (R1 + R2)/R2, VCC > Vth2; vin0 is a bus voltage threshold, vth1 is a start voltage of the driving switch Q2, vth2 is a start voltage of the capacitor switch Q1, VCC is a first voltage, and R1 and R2 are respectively a resistance value of the first voltage-dividing resistor R1 and a resistance value of the second voltage-dividing resistor R2. When the voltage on the bus is greater than the bus voltage threshold Vin0, the voltage on the control end of the driving switch tube Q2 (i.e. the voltage of the second voltage-dividing resistor R2) is greater than the starting voltage Vth1 of the driving switch tube Q2, the driving switch tube Q2 is controlled to be switched on, the voltage on the control end of the capacitor switch Q1 is pulled down and is less than the starting voltage Vth2 of the capacitor switch Q1, so that the capacitor switch Q1 is switched off, and the second bus capacitor C2 is not connected to the charge-discharge loop of the bus; when the voltage on the bus is smaller than the bus voltage threshold Vin0, the voltage on the control end of the driving switch tube Q2 (i.e. the voltage of the second voltage-dividing resistor R2) is smaller than the starting voltage Vth1 of the driving switch tube Q2, the driving switch tube Q2 is controlled to be turned off, the voltage on the control end of the capacitor switch Q1 is pulled up to a first voltage by the pull-up resistor R5, and the first voltage is greater than the starting voltage Vth2 of the capacitor switch Q1, so that the capacitor switch Q1 is turned on, and the second bus capacitor C2 is connected to the charge-discharge loop of the bus.
The invention also provides a switching converter comprising any one of the AC-DC conversion circuits.
The invention also provides a control method of the AC-DC conversion circuit, the capacitance switch control circuit detects the voltage on the bus; when the voltage on the bus is smaller than the bus voltage threshold value, the capacitance switch control circuit controls the conduction of the capacitance switch, so that the second bus capacitor is connected to a charge-discharge loop of the bus; when the voltage on the bus is larger than or equal to the bus voltage threshold value, the capacitor switch control circuit controls the capacitor switch to be switched off, so that the second bus capacitor is not connected to the charge-discharge loop of the bus.
It will be appreciated by those skilled in the art that the above-described preferred embodiments may be freely combined, superimposed, without conflict.
It will be understood that the embodiments described above are illustrative only and not restrictive, and that various obvious or equivalent modifications and substitutions for details shown and described herein may be made by those skilled in the art without departing from the basic principles of the present invention.
Claims (11)
1. An AC-DC conversion circuit comprises a rectification circuit, a first bus capacitor and a DC-DC conversion unit, wherein the rectification circuit is used for rectifying input alternating current voltage to obtain direct current voltage and supplying the direct current voltage to a bus, one end of the first bus capacitor is connected with the bus, the other end of the first bus capacitor is connected with the ground, and the DC-DC conversion unit is used for converting the voltage on the bus into output target voltage;
the second bus capacitor and the capacitor switch are connected in series between the bus and the ground;
the capacitance switch control circuit detects the voltage on the bus, and when the voltage on the bus is smaller than a bus voltage threshold value, the capacitance switch control circuit controls the capacitor switch to be conducted, so that the second bus capacitor is connected to a charge-discharge loop of the bus; when the voltage on the bus is larger than or equal to the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be switched off, so that the second bus capacitor is not connected to the charge-discharge loop of the bus.
2. The AC-DC conversion circuit according to claim 1,
the capacitance switch control circuit comprises a first resistance voltage division circuit, a driving switch tube and a pull-up resistor;
the first resistance voltage division circuit comprises a first voltage division resistor and a second voltage division resistor, the first voltage division resistor and the second voltage division resistor are connected between the bus and the ground in series, a common end of the first voltage division resistor and the second voltage division resistor is connected with a control end of the driving switch tube, the control end of the driving switch tube is grounded through the second voltage division resistor, a current inflow end of the driving switch tube is connected with the control end of the capacitance switch, a current outflow end of the driving switch tube is connected with the ground, and the control end of the capacitance switch is connected with a first voltage through the pull-up resistor;
and satisfies: vin0= Vth1 (R1 + R2)/R2, VCC > Vth2;
vin0 is the bus voltage threshold, vth1 is the start voltage of the driving switch tube, vth2 is the start voltage of the capacitor switch, VCC is the magnitude of the first voltage, and R1 and R2 are the resistance value of the first divider resistor and the resistance value of the second divider resistor, respectively.
3. The AC-DC conversion circuit of claim 1,
the capacitance switch control circuit comprises a first resistance voltage division circuit, a driving switch tube and a second resistance voltage division circuit;
the first resistance voltage division circuit comprises a first voltage division resistor and a second voltage division resistor, the first voltage division resistor and the second voltage division resistor are connected between the bus and the ground in series, the common end of the first voltage division resistor and the second voltage division resistor is connected with the control end of the driving switch tube, and the control end of the driving switch tube is grounded through the second voltage division resistor;
the second resistance voltage division circuit comprises a third voltage division resistor and a fourth voltage division resistor, the third voltage division resistor and the fourth voltage division resistor are connected between a first voltage and the ground in series, a common end of the third voltage division resistor and a common end of the fourth voltage division resistor are connected with a control end of the capacitive switch, and the control end of the capacitive switch is grounded through the fourth voltage division resistor;
the current inflow end of the driving switch tube is connected with the control end of the capacitance switch, and the current outflow end of the driving switch tube is connected with the ground;
and satisfies the following conditions: vin0= Vth1 (R1 + R2)/R2, VCC R4/(R3 + R4) > Vth2;
vin0 is the bus voltage threshold, vth1 is the start voltage of the driving switch tube, vth2 is the start voltage of the capacitor switch, VCC is the magnitude of the first voltage, and R1, R2, R3, and R4 are the resistance value of the first voltage dividing resistor, the resistance value of the second voltage dividing resistor, the resistance value of the third voltage dividing resistor, and the resistance value of the fourth voltage dividing resistor, respectively.
4. The AC-DC conversion circuit of claim 1,
the driving switch tube is connected with the first bus capacitor, the driving switch tube is connected with the second bus capacitor, and the driving switch tube is connected with the second bus capacitor.
5. The AC-DC conversion circuit according to claim 1,
the capacity of the second bus capacitor is greater than the capacity of the first bus capacitor.
6. The AC-DC conversion circuit according to claim 1,
the DC-DC conversion unit is a flyback DC-DC conversion unit.
7. The AC-DC conversion circuit according to claim 1,
the bus is grounded through the second bus capacitor and the capacitor switch in sequence.
8. A switching converter comprising an AC-DC conversion circuit according to any one of claims 1 to 7.
9. A control method of an AC-DC conversion circuit according to claim 1,
the capacitance switch control circuit detects the voltage on the bus;
when the voltage on the bus is smaller than the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be conducted, so that the second bus capacitor is connected to a charge-discharge loop of the bus;
when the voltage on the bus is larger than or equal to the bus voltage threshold value, the capacitance switch control circuit controls the capacitance switch to be switched off, so that the second bus capacitor is not connected to the charge-discharge loop of the bus.
10. The control method according to claim 9, wherein the AC-DC conversion circuit according to claim 2 is employed,
when the voltage on the bus is less than Vth1 (R1 + R2)/R2, the driving switch tube is controlled to be switched off, the voltage of the control end of the capacitance switch is pulled up to the first voltage, and the capacitance switch is controlled to be switched on;
when the voltage on the bus is greater than or equal to Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be on, the voltage of the control end of the capacitive switch is pulled down to zero, and the capacitive switch is controlled to be off.
11. The control method according to claim 9, wherein the AC-DC conversion circuit according to claim 3 is employed,
when the voltage on the bus is less than Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be switched off, and the voltage of the control end of the capacitive switch is maintained at the voltage of the fourth voltage dividing resistor, so that the capacitive switch is controlled to be switched on;
when the voltage on the bus is greater than or equal to Vth1 × (R1 + R2)/R2, the driving switch tube is controlled to be on, the voltage of the control end of the capacitive switch is pulled down to zero, and the capacitive switch is controlled to be off.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210986303.XA CN115842467A (en) | 2022-08-17 | 2022-08-17 | Switch converter, AC-DC conversion circuit and control method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202210986303.XA CN115842467A (en) | 2022-08-17 | 2022-08-17 | Switch converter, AC-DC conversion circuit and control method |
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| Publication Number | Publication Date |
|---|---|
| CN115842467A true CN115842467A (en) | 2023-03-24 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210986303.XA Pending CN115842467A (en) | 2022-08-17 | 2022-08-17 | Switch converter, AC-DC conversion circuit and control method |
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| Country | Link |
|---|---|
| CN (1) | CN115842467A (en) |
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2022
- 2022-08-17 CN CN202210986303.XA patent/CN115842467A/en active Pending
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