CN116131219B - Overvoltage protection circuit and electronic device - Google Patents
Overvoltage protection circuit and electronic device Download PDFInfo
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- CN116131219B CN116131219B CN202310123412.3A CN202310123412A CN116131219B CN 116131219 B CN116131219 B CN 116131219B CN 202310123412 A CN202310123412 A CN 202310123412A CN 116131219 B CN116131219 B CN 116131219B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0064—Magnetic structures combining different functions, e.g. storage, filtering or transformation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/34—Snubber circuits
- H02M1/346—Passive non-dissipative snubbers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The invention discloses an overvoltage protection circuit and an electronic device, wherein the overvoltage protection circuit comprises: the detection module is configured to detect and output a detection voltage; the comparison module is coupled with the detection voltage and a preset reference voltage; determining whether the load voltage of the power supply system is overvoltage or not based on a comparison result of the detection voltage and a preset reference voltage; and if the detection voltage is greater than or equal to the preset reference voltage, determining that the load voltage of the power supply system is overvoltage. The overvoltage protection circuit provided by the invention has a simple structure and accurate detection result.
Description
Technical Field
The invention relates to the technical field of power supply conversion, in particular to an overvoltage protection circuit and an electronic device.
Background
The existing driving power supply basically has an overvoltage protection mechanism, and the load voltage does not exceed the withstand voltage of the output capacitor through the overvoltage protection mechanism, otherwise, the output capacitor is easy to burn out. For example, an overvoltage protection voltage threshold is typically set, and when the load voltage exceeds the overvoltage protection voltage threshold, the load voltage is considered to be overvoltage.
In existing driving power supplies, particularly for applications where the load floats relative to a reference zero voltage, it is often difficult to accurately detect and directly determine whether the load voltage is over-voltage, so improvements are needed.
Disclosure of Invention
In a first aspect, an embodiment of the present invention provides an overvoltage protection circuit applied to a power supply system having a transformer, where an auxiliary winding and a main winding of the transformer have identical terminals at the same position, the overvoltage protection circuit includes:
the detection module comprises the auxiliary winding and a second power switch which is coupled with the auxiliary winding in series, and is configured to detect and output a detection voltage;
the comparison module is coupled with the detection voltage and a preset reference voltage;
determining whether the load voltage of the power supply system is over-voltage or not based on a comparison result of the detection voltage and a preset reference voltage during the charging period of the main-stage winding; and if the detection voltage is greater than or equal to the preset reference voltage, determining that the load voltage of the power supply system is overvoltage.
Preferably, during charging of the primary winding, the detection module outputs the detection voltage at the common terminal of the auxiliary winding and the second power switch, the detection voltage being equal or approximately equal to the load voltage or a multiple of the load voltage.
Preferably, the comparison module of the overvoltage protection circuit outputs an enabled comparison result of a high level or a low level during charging of the main-stage winding; the comparison result output during the discharge of the primary winding is fixed to a low level or disabled.
Preferably, the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, an overvoltage protection circuit, a control module and a power stage, wherein the power stage comprises a main stage winding, a freewheel module and a first power switch; the first end of the output capacitor is coupled with the first end of the input capacitor and the same-name end of the auxiliary winding, the second end of the input capacitor is coupled with the ground, the second end of the output capacitor is coupled with the same-name end of the main-stage winding of the transformer, the non-same-name end of the main-stage winding is coupled with the first end of the first power switch and the first end of the follow current module, and the control end of the first power switch is coupled with the control module; the second end of the follow current module is coupled with the first end of the input capacitor; after the load voltage is over-voltage, the comparison result output by the over-voltage protection circuit enables the first power switch to be cut off through the control module.
Preferably, the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, an overvoltage protection circuit, a control module and a power stage, wherein the power stage comprises a main stage winding, a freewheel module and a first power switch; the second end of the output capacitor is coupled with the first end of the input capacitor and the same-name end of the main-stage winding, the second end of the input capacitor is coupled with the ground, the first end of the output capacitor is coupled with the second end of the freewheel module and the same-name end of the auxiliary winding, the first end of the freewheel module is coupled with the non-same-name end of the main-stage winding and the first end of the first power switch, and the control end of the first power switch is coupled with the control module; after the load voltage is over-voltage, the comparison result output by the over-voltage protection circuit enables the first power switch to be cut off through the control module.
Preferably, the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, an overvoltage protection circuit, a control module, a power stage and an absorption circuit, wherein the power stage comprises a main stage winding and a secondary winding of a transformer, a freewheel module and a first power switch; the absorption circuit comprises an absorption diode and an absorption capacitor; the first end of the input capacitor is coupled with the homonymous end of the main-stage winding and the second end of the absorption capacitor, the second end of the input capacitor is coupled with the ground, the first end of the absorption capacitor is coupled with the homonymous end of the auxiliary winding and the cathode of the absorption diode, the non-homonymous end of the main-stage winding is coupled with the first end of the first power switch and the anode of the absorption diode, and the control end of the first power switch is coupled with the control module; the first end of the output capacitor is coupled with the second end of the follow current module, the first end of the follow current module is coupled with the non-homonymous end of the secondary winding, and the homonymous end of the secondary winding is coupled with the second end of the output capacitor; or the first end of the output capacitor is coupled with the non-homonymous end of the secondary winding, the second end of the output capacitor is coupled with the first end of the freewheel module, and the second end of the freewheel module is coupled with the homonymous end of the secondary winding; after the load voltage is over-voltage, the comparison result output by the over-voltage protection circuit enables the first power switch to be cut off through the control module. Preferably, the comparison module is further coupled to the control terminal of the first power switch, and the comparison module performs load overvoltage comparison and outputs a comparison result only during the period that the signal of the control terminal of the first power switch charges the main stage winding.
Preferably, before the control module controls the first power switch to be turned on, the control module controls the second power switch in the detection module to be turned on for a pulse time to charge the auxiliary winding, and after the voltage across the two ends of the first power switch is reduced to zero voltage or approximately zero voltage through the coupling relation of the transformer, the control module controls the first power switch to be turned on.
Preferably, the comparison module comprises a first switch, a second switch, a first inverter and a first comparator, wherein during the enabling period of the control end of the first power switch, the first switch is turned on, the second switch is turned off, the detection voltage is compared with the preset reference voltage through the first comparator, and the enabled comparison result of high level or low level is output; during the control end non-enabling period of the first power switch, the first switch is turned off, the second switch is turned on, and the comparison result output by the first comparator is fixed to be low level or not enabled.
In a second aspect, an embodiment of the present invention provides an electronic device, including an overvoltage protection circuit according to any one of the first aspects.
The technology of the invention has the following advantages:
according to the overvoltage protection circuit provided by the embodiment of the invention, the auxiliary winding for reducing the switching loss of the power supply system is multiplexed, and the reference voltage and the load voltage can be indirectly compared directly, so that the detection precision of the overvoltage protection circuit is improved, and the volume and the cost of the whole driving power supply are reduced.
The overvoltage protection circuit adopting the technology has smaller area, lower cost and higher precision.
Drawings
FIG. 1 is a simplified block diagram of an overvoltage protection circuit according to one embodiment of the present invention;
FIG. 2 is a power supply system with an overvoltage protection circuit according to an embodiment of the present invention;
FIG. 3 is a power supply system with an overvoltage protection circuit according to another embodiment of the present invention;
FIG. 4 is a power supply system with an overvoltage protection circuit according to yet another embodiment of the present invention;
fig. 5 is a simplified circuit of a comparison module according to an embodiment of the invention.
Various features and elements are not drawn to scale in accordance with conventional practice in the drawings in order to best illustrate the specific features and elements associated with the invention. In addition, like elements/components are referred to by the same or similar reference numerals among the different drawings.
[ symbolic description ]
11: first power supply system
110: overvoltage protection circuit
1101: detection module
1102: comparison module
11021: first switch
11022: second switch
11023: first inverter
11024: first comparator
112: control module
12: second power supply system
120: second power stage
121: freewheel module
13: third power supply system
130: third power stage
14: fourth power supply system
140: fourth power stage
141: absorption circuit
MP: first power switch
MA: second power switch
GATE: control terminal
Vds: cross-over pressure
SWA: detecting voltage
T1: transformer
Lp: main-stage winding
Ls: secondary winding
La: auxiliary winding
Nps: turns ratio
Dlp: absorption diode
Clp: absorption capacitor
VREF: reference voltage
OVP: comparison result
CIN: input capacitance
CO: output capacitor
VIN: input voltage
VO: load voltage.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In a first aspect, as shown in fig. 1, an embodiment of the present invention provides a simplified structure diagram of an overvoltage protection circuit 110, applied to a first power supply system 11 having a transformer T1, where an auxiliary winding La and a main winding Lp of the transformer T1 have identical ends at the same position, the overvoltage protection circuit 110 includes: a detection module 1101, including an auxiliary winding La and a second power switch MA coupled in series with the auxiliary winding La, wherein the detection module 1101 is configured to detect and output a detection voltage SWA; a comparison module 1102 coupled to the detection voltage SWA and a predetermined reference voltage VREF; determining whether the load voltage of the first power supply system 11 is over-voltage based on a comparison result of the detection voltage SWA and a preset reference voltage VREF during charging of the main stage winding Lp; if the detected voltage SWA is equal to or greater than the preset reference voltage VREF, the load voltage overvoltage of the first power supply system 11 is determined.
The homonymous ends of the two windings of the transformer are defined as follows: when current flows into (or out of) two windings simultaneously from one end of each winding respectively, if magnetic fluxes generated by the two windings are aided, the two ends are called as homonymous ends of the transformer winding, and black dots "·" or asterisks are used for marking. The positions of the homonymous terminals can be defined by themselves, the inflow terminals can be called homonymous terminals, and the outflow terminals can be called homonymous terminals.
In one embodiment, during charging of the primary winding Lp, the detection module 1101 outputs a detection voltage SWA at the common terminal of the auxiliary winding La and the second power switch MA, which is equal or approximately equal to the load voltage VO or a multiple of the load voltage VO. By approximately equal, the first case is that during charging of the primary winding Lp, the conduction voltage drop of the first power switch MP is ignored, or the voltage drop of a current detection resistor possibly connected in series between the second end of the first power switch MP and the ground is ignored, then the voltage drop across the primary inductor Lp is approximately equal to VIN-VO, and under the coupling action of the transformer T1, the voltage drop across the auxiliary winding La is also approximately equal to VIN-VO, and the detection voltage SWA is approximately equal to VIN- (VIN-VO) =vo, under the condition that the number of turns of the primary winding Lp and the auxiliary winding La are the same; the second case is a case where the number of turns of the main winding Lp and the auxiliary winding La is approximately the same, for example, the deviation of the number of turns of the main winding Lp and the auxiliary winding La is about 1%, and the voltage on the auxiliary winding La is considered to be approximately equal to the voltage on the main winding Lp.
In order to make it possible to more clearly and simply describe the working principle of the present invention, the embodiments in this specification only exemplify the case that the number of turns of the main winding Lp and the auxiliary winding La of the transformer T1 is the same, and in the practical implementation process, the deviation of the number of turns of the main winding Lp and the auxiliary winding La of the transformer T1 is kept within the acceptable deviation range in engineering application, and does not affect the working principle of the present invention.
In one embodiment, as shown in fig. 2, the second power supply system 12 includes an input capacitance CIN, an output capacitance CO coupled in parallel with a load, an overvoltage protection circuit 110, a control module 112, and a second power stage 120, the second power stage 120 including a main stage winding Lp, a freewheel module 121, and a first power switch MP.
In one embodiment, the freewheel module 121 is composed of diodes, and the power stages including the diodes constitute an asynchronous rectification structure.
In one embodiment, the freewheel module 121 is composed of a field effect transistor (MOSFET), and the power stage including the field effect transistor constitutes a synchronous rectification structure.
In one embodiment, the comparison module 1102 is further coupled to the control terminal GATE of the first power switch MP, and the comparison module 1102 performs the load VO over-voltage comparison and outputs the comparison result OVP only during the period when the signal of the control terminal GATE of the first power switch MP charges the main winding Lp.
In one embodiment, the comparison module 1102 of the overvoltage protection circuit 110 outputs an enable comparison result OVP of high or low level during charging of the main stage winding Lp; the comparison result OVP output during discharge of the main stage winding Lp is fixed to a low level.
In one embodiment, as shown in fig. 2, the second power supply system 12 includes an input capacitance CIN, an output capacitance CO coupled in parallel to a load, an overvoltage protection circuit 110, a control module 112, and a second power stage 120, the second power stage 120 including a main stage winding Lp, a freewheel module 121, and a first power switch MP; before the control module 112 controls the first power switch MP to be turned on, the control module 112 controls the second power switch MA in the detection module 1101 to be turned on for a pulse time to charge the auxiliary winding La, and after the voltage across Vds at two ends of the first power switch MP is reduced to zero voltage or approximately zero voltage through the coupling relation of the transformer T1, the control module 112 controls the first power switch MP to be turned on; the first end of the output capacitor CO is coupled with the first end of the input capacitor CIN and the same-name end of the auxiliary winding La, the second end of the input capacitor CIN is coupled with the ground, the second end of the output capacitor CO is coupled with the same-name end of the main-stage winding Lp of the transformer T1, the non-same-name end of the main-stage winding Lp is coupled with the first end of the first power switch MP and the first end of the follow current module 121, and the control end GATE of the first power switch MP is coupled with the control module 112; a second terminal of the freewheel module 121 is coupled to the first terminal of the input capacitance CIN; the second power supply system 12 belongs to a step-down power supply system, when the first power switch MP is turned on, the input voltage VIN charges the main winding Lp through the load and the output capacitor CO, at this time, the voltage drop on the main winding Lp is approximately VIN-VO (neglecting the conduction voltage drop of the first power switch MP), and by the coupling relationship of the transformer T1, the voltage drop on the auxiliary winding La is also kept at VIN-VO or approximately equal to VIN-VO under the condition that the turns of the main winding Lp and the auxiliary winding La are the same or approximately the same; during charging of the main stage winding Lp, the voltage drop across the second power switch MA is VIN- (VIN-VO) =vo, so that the detection voltage SWA output by the auxiliary winding La and the common terminal of the second power switch MA is equal or approximately equal to the load voltage VO. The comparison module 1102 compares the detection voltage SWA with a preset reference voltage VREF, and when the detection voltage SWA is greater than or equal to the reference voltage VREF, which indicates that the load voltage VO is over-voltage, the comparison result OVP output by the over-voltage protection circuit 110 turns off the first power switch MP through the control module 112.
In one embodiment, as shown in fig. 3, the third power supply system 13 includes an input capacitor CIN, an output capacitor CO coupled in parallel to a load, an overvoltage protection circuit 110, a control module 112, and a third power stage 130, the third power stage 130 including a main stage winding Lp, a freewheel module 121, and a first power switch MP; before the control module 112 controls the first power switch MP to be turned on, the control module 112 controls the second power switch MA in the detection module 1101 to be turned on for a pulse time to charge the auxiliary winding La, and after the voltage across Vds at two ends of the first power switch MP is reduced to zero voltage or approximately zero voltage through the coupling relation of the transformer T1, the control module 112 controls the first power switch MP to be turned on; the second end of the output capacitor CO is coupled with the first end of the input capacitor CIN and the same-name end of the main-stage winding Lp, the second end of the input capacitor CIN is coupled with the ground, the first end of the output capacitor CO is coupled with the second end of the freewheel module 121 and the same-name end of the auxiliary winding La, the first end of the freewheel module 121 is coupled with the non-same-name end of the main-stage winding Lp and the first end of the first power switch MP, and the control end GATE of the first power switch MP is coupled with the control module 112; the third power supply system 13 belongs to a step-up/down power supply system, and when the first power switch MP is turned on, the input voltage VIN charges the main winding Lp, at this time, the voltage drop across the main winding Lp is approximately VIN (neglecting the on voltage drop of the first power switch MP), and by means of the coupling relationship of the transformer T1, the voltage drop across the auxiliary winding La is also kept at VIN or approximately VIN when the number of turns of the main winding Lp and the auxiliary winding La are the same or approximately the same; during charging of the main stage winding Lp, the voltage drop across the second power switch MA is (vin+vo) -vin=vo, so that the detection voltage SWA output by the auxiliary winding La and the common terminal of the second power switch MA is equal or approximately equal to the load voltage VO. The comparison module 1102 compares the detection voltage SWA with a preset reference voltage VREF, and when the detection voltage SWA is greater than or equal to the reference voltage VREF, which indicates that the load voltage VO is over-voltage, the comparison result OVP output by the over-voltage protection circuit 110 turns off the first power switch MP through the control module 112.
In one embodiment, as shown in fig. 4, the fourth power supply system 14 includes an input capacitance CIN, an output capacitance CO coupled in parallel to a load, an overvoltage protection circuit 110, a control module 112, a fourth power stage 140, and an absorption circuit 141, the fourth power stage 140 including a primary winding Lp and a secondary winding Ls of a transformer T1, a freewheel module 121, and a first power switch MP; before the control module 112 controls the first power switch MP to be turned on, the control module 112 controls the second power switch MA in the detection module 1101 to be turned on for a pulse time to charge the auxiliary winding La, and after the voltage across Vds at two ends of the first power switch MP is reduced to zero voltage or approximately zero voltage through the coupling relation of the transformer T1, the control module 112 controls the first power switch MP to be turned on; the snubber circuit 141 includes a snubber diode Dlp and a snubber capacitor Clp; the first end of the input capacitor CIN is coupled with the same-name end of the main stage winding Lp and the second end of the absorption capacitor Clp, the second end of the input capacitor CIN is coupled with the ground, the non-same-name end of the main stage winding Lp is coupled with the first end of the first power switch MP and the anode of the absorption diode Dlp, the cathode of the absorption diode Dlp is coupled with the first end of the absorption capacitor Clp and the same-name end of the auxiliary winding La, and the control end GATE of the first power switch MP is coupled with the control module 112; the first end of the output capacitor CO is coupled with the second end of the follow current module 121, the first end of the follow current module 121 is coupled with the non-homonymous end of the secondary winding Ls, and the homonymous end of the secondary winding Ls is coupled with the second end of the output capacitor CO; or the first end of the output capacitor CO is coupled with the non-homonymous end of the secondary winding Ls, the second end of the output capacitor CO is coupled with the first end of the freewheel module 121, and the second end of the freewheel module 121 is coupled with the homonymous end of the secondary winding Ls; the fourth power supply system 14 belongs to a flyback power supply system, when the first power switch MP is turned on, the input voltage VIN charges the main winding Lp, at this time, the voltage drop across the main winding Lp is approximately VIN (neglecting the on-voltage drop of the first power switch MP), and by the coupling relationship of the transformer T1, the voltage drop across the auxiliary winding La is also kept at VIN or approximately VIN when the number of turns of the main winding Lp and the auxiliary winding La are the same or approximately the same; during charging of the primary winding Lp, the voltage drop across the second power switch MA is (vin+ Nps ×vo) -vin= Nps ×vo, (Nps is the turns ratio of the primary winding Lp to the secondary winding Ls), so the detection voltage SWA output by the common terminal of the auxiliary winding La and the second power switch MA is equal to or approximately equal to Nps times the load voltage VO. The comparison module 1102 compares the detection voltage SWA with a preset reference voltage VREF, and when the detection voltage SWA is greater than or equal to the reference voltage VREF, which indicates that the load voltage VO is over-voltage, the comparison result OVP output by the over-voltage protection circuit 110 turns off the first power switch MP through the control module 112. In one embodiment, the comparison module directly compares the detection voltage SWA with a lower reference voltage after the detection voltage SWA is scaled down by the voltage dividing circuit to determine whether the load voltage VO is over-voltage.
In one embodiment, the load voltage VO may be approximately obtained by setting a winding ratio relationship of the auxiliary winding La and the main winding Lp, so as to approximately determine whether the load voltage VO is over-voltage.
In one embodiment, the load voltage VO may be determined whether it is over-voltage by sampling the output detection voltage SWA and comparing it with a reference voltage.
In one embodiment, before the control module 112 controls the first power switch MP to be turned on, the control module 112 controls the second power switch MA in the detection module 1101 to be turned on for a pulse time to charge the auxiliary winding La, so that the voltage across Vds of the two ends of the first power switch MP is reduced to zero voltage or approximately zero voltage through the coupling relationship of the transformer T1, and then the control module 112 controls the first power switch MP to be turned on, so as to realize that the first power switch MP works in the zero voltage state.
In one embodiment, as shown in fig. 5, the comparison module 1102 includes a first switch 11021, a second switch 11022, a first inverter 11023 and a first comparator 11024, wherein during a control end GATE enable period of the first power switch MP, the first switch 11021 is turned on, the second switch 11022 is turned off, the detection voltage SWA is compared with a preset reference voltage VREF through the first comparator 11024, and a comparison result OVP of a high level or a low level is output; during the period when the control terminal GATE of the first power switch MP is not enabled, the first switch 11021 is turned off, the second switch 11022 is turned on, and the output result of the first comparator 11024 is fixed to be low level.
In a second aspect, an embodiment of the present invention further provides an electronic device, including an overvoltage protection circuit according to any one of the first aspects.
From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:
1) According to the overvoltage protection circuit, during charging of the main-stage winding Lp, the load voltage VO is indirectly detected at the detection voltage SWA of the common end of the second power switch MA and the auxiliary winding La, and overvoltage judgment of the auxiliary voltage is accurately achieved through direct comparison between the detection voltage SWA and the reference voltage VREF.
2) According to the electronic device, during the charging period of the main-stage winding Lp, the load voltage VO is indirectly detected at the detection voltage SWA of the common end of the second power switch MA and the auxiliary winding La, and the overvoltage judgment of the auxiliary voltage is accurately realized through direct comparison between the detection voltage SWA and the reference voltage VREF.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.
It should also be noted that, in this document, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements to be referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Moreover, relational terms such as "first" and "second" may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions, or order, and without necessarily being construed as indicating or implying any relative importance. "and/or" means either or both of which may be selected. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or terminal device comprising the element.
The foregoing has outlined rather broadly the more detailed description of the invention in order that the detailed description of the invention that follows may be better understood, and in order that the present contribution to the art may be better appreciated. While various modifications of the embodiments and applications of the invention will occur to those skilled in the art, it is not necessary and not intended to be exhaustive of all embodiments, and obvious modifications or variations of the invention are within the scope of the invention.
Claims (10)
1. An overvoltage protection circuit for use in a power supply system having a transformer with auxiliary windings and primary windings having identical ends in identical positions, the overvoltage protection circuit comprising:
the detection module comprises an auxiliary winding and a second power switch coupled in series with the auxiliary winding, and is configured to detect and output a detection voltage at a common end of the auxiliary winding and the second power switch during charging of the main winding;
the same-name end of the auxiliary winding is coupled with the first end of the input capacitor, the same-name end of the main-stage winding is coupled with the first end of the input capacitor through the output capacitor, and the load is coupled with the output capacitor in parallel; or (b)
The same-name end of the auxiliary winding is coupled with the first end of the input capacitor through the output capacitor, the load is coupled with the output capacitor in parallel, and the same-name end of the main-stage winding is coupled with the first end of the input capacitor; or (b)
The same-name end of the auxiliary winding is coupled with the first end of the input capacitor through the absorption capacitor, the load is coupled with the output capacitor in parallel, the same-name end of the main-stage winding is coupled with the first end of the input capacitor, and the non-same-name end of the main-stage winding is coupled with the first end of the input capacitor sequentially through the absorption diode and the absorption capacitor;
the comparison module is coupled with the detection voltage and a preset reference voltage;
determining whether the load voltage of the power supply system is over-voltage or not based on a comparison result of the detection voltage and a preset reference voltage during the charging period of the main-stage winding; and if the detection voltage is greater than or equal to the preset reference voltage, determining that the load voltage of the power supply system is overvoltage.
2. The overvoltage protection circuit according to claim 1, wherein the detection voltage is equal or approximately equal to the load voltage or a multiple of the load voltage.
3. The overvoltage protection circuit of claim 1, wherein the comparison module of the overvoltage protection circuit outputs a comparison of high or low level enabling during charging of the primary winding; the comparison result output during the discharge of the primary winding is fixed to a low level or disabled.
4. The overvoltage protection circuit of claim 1, wherein the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, an overvoltage protection circuit, a control module, and a power stage comprising a primary winding, a freewheel module, and a first power switch; the first end of the output capacitor is coupled with the first end of the input capacitor and the same-name end of the auxiliary winding, the second end of the output capacitor is coupled with the same-name end of the main-stage winding of the transformer, the non-same-name end of the main-stage winding is coupled with the first end of the first power switch and the first end of the follow current module, and the control end of the first power switch is coupled with the control module; the second end of the follow current module is coupled with the first end of the input capacitor; after the load voltage is over-voltage, the comparison result output by the over-voltage protection circuit enables the first power switch to be cut off through the control module.
5. The overvoltage protection circuit of claim 1, wherein the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, an overvoltage protection circuit, a control module, and a power stage comprising a primary winding, a freewheel module, and a first power switch; the second end of the output capacitor is coupled with the first end of the input capacitor and the same-name end of the main-stage winding, the first end of the output capacitor is coupled with the second end of the follow current module and the same-name end of the auxiliary winding, the first end of the follow current module is coupled with the non-same-name end of the main-stage winding and the first end of the first power switch, and the control end of the first power switch is coupled with the control module; after the load voltage is over-voltage, the comparison result output by the over-voltage protection circuit enables the first power switch to be cut off through the control module.
6. The overvoltage protection circuit of claim 1, wherein the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, an overvoltage protection circuit, a control module, a power stage and an absorption circuit, the power stage comprising a primary and secondary winding of a transformer, a freewheel module and a first power switch; the absorption circuit comprises an absorption diode and an absorption capacitor; the first end of the input capacitor is coupled with the homonymous end of the main-stage winding and the second end of the absorption capacitor, the first end of the absorption capacitor is coupled with the homonymous end of the auxiliary winding and the cathode of the absorption diode, the non-homonymous end of the main-stage winding is coupled with the first end of the first power switch and the anode of the absorption diode, and the control end of the first power switch is coupled with the control module; the first end of the output capacitor is coupled with the second end of the follow current module, the first end of the follow current module is coupled with the non-homonymous end of the secondary winding, and the homonymous end of the secondary winding is coupled with the second end of the output capacitor; or the first end of the output capacitor is coupled with the non-homonymous end of the secondary winding, the second end of the output capacitor is coupled with the first end of the freewheel module, and the second end of the freewheel module is coupled with the homonymous end of the secondary winding; after the load voltage is over-voltage, the comparison result output by the over-voltage protection circuit enables the first power switch to be cut off through the control module.
7. The overvoltage protection circuit according to any one of claims 4 to 6, wherein the comparison module is further coupled to the control terminal of the first power switch, and wherein the comparison module performs the load overvoltage comparison and outputs the comparison result only during the period when the signal of the control terminal of the first power switch causes the main stage winding to charge.
8. The overvoltage protection circuit according to any one of claims 4 to 6, wherein the control module controls the second power switch in the detection module to conduct for a pulse time to charge the auxiliary winding before the first power switch is controlled to conduct, and controls the first power switch to conduct after the voltage across the first power switch is reduced to zero or approximately zero voltage through the coupling relationship of the transformer.
9. The overvoltage protection circuit according to claim 1, wherein the comparison module comprises a first switch, a second switch, a first inverter and a first comparator, the first switch is turned on and the second switch is turned off during the enabling period of the control end of the first power switch, and the detection voltage is compared with the preset reference voltage through the first comparator, so that the enabling comparison result of high level or low level is output; during the control end non-enabling period of the first power switch, the first switch is turned off, the second switch is turned on, and the comparison result output by the first comparator is fixed to be low level or not enabled.
10. An electronic device comprising the overvoltage protection circuit of any one of claims 1 to 9.
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| CN202310123412.3A CN116131219B (en) | 2023-02-16 | 2023-02-16 | Overvoltage protection circuit and electronic device |
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| CN202310123412.3A CN116131219B (en) | 2023-02-16 | 2023-02-16 | Overvoltage protection circuit and electronic device |
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