CN116317602A - Demagnetizing detection circuit, power supply system and electronic device - Google Patents

Demagnetizing detection circuit, power supply system and electronic device Download PDF

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Publication number
CN116317602A
CN116317602A CN202310251289.3A CN202310251289A CN116317602A CN 116317602 A CN116317602 A CN 116317602A CN 202310251289 A CN202310251289 A CN 202310251289A CN 116317602 A CN116317602 A CN 116317602A
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CN
China
Prior art keywords
voltage
demagnetization
power switch
transformer
comparator
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CN202310251289.3A
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Chinese (zh)
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请求不公布姓名
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Ensai Semiconductor Chengdu Co ltd
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Ensai Semiconductor Chengdu Co ltd
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Priority to CN202310251289.3A priority Critical patent/CN116317602A/en
Publication of CN116317602A publication Critical patent/CN116317602A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/12—Measuring magnetic properties of articles or specimens of solids or fluids
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • 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
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • 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
    • H02M3/33592—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 having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a demagnetizing detection circuit, a power supply system and an electronic device, wherein the demagnetizing detection circuit comprises: the auxiliary winding is provided with two ends, and the first end of the auxiliary winding is coupled with the first end of the input capacitor or is coupled with the first end of the input capacitor after passing through the capacitor; a detection module coupled to the second end of the auxiliary winding, at least comprising a second power switch, the detection module configured to detect a demagnetized state of the transformer; and the comparison module is coupled with the detection module, and is configured to compare the voltage of one node of the detection module and output a demagnetizing signal which indicates that the demagnetization of the transformer is finished. The demagnetizing detection circuit provided by the invention improves the reliability of detecting the demagnetizing state of the power supply system.

Description

Demagnetizing detection circuit, power supply system and electronic device
Technical Field
The invention relates to the technical field of power supply conversion, in particular to a demagnetization detection circuit, a power supply system and an electronic device.
Background
In order to output a preset voltage or current, a power supply system is generally required to detect the demagnetizing state of a transformer or an inductor, LC resonance is generated between the transformer or the inductor and parasitic capacitance of a power switch after demagnetization, and particularly when the power switch of the power supply system is disposed outside a driving chip of the power supply system, reliability of detecting the demagnetizing state of the transformer or the inductor is deteriorated due to interference caused by routing of a Printed Circuit Board (PCB), so that improvement is required.
Disclosure of Invention
The embodiment of the invention provides a demagnetization detection circuit, a power supply system and an electronic device.
In a first aspect, an embodiment of the present invention provides a demagnetization detecting circuit applied to a power supply system having a transformer, an input capacitor and an output capacitor, where the transformer has at least an auxiliary winding and a main winding, and the demagnetization detecting circuit includes:
the auxiliary winding is provided with two ends, and the first end of the auxiliary winding is coupled with the first end of the input capacitor or is coupled with the first end of the input capacitor after passing through the capacitor;
a detection module coupled to the second end of the auxiliary winding, at least comprising a second power switch, the detection module configured to detect a demagnetized state of the transformer;
and the comparison module is coupled with the detection module, and is configured to compare the voltage of one node of the detection module and output a demagnetizing signal which indicates that the demagnetization of the transformer is finished.
Preferably, the auxiliary winding and the main winding of the transformer have identical-name ends at the same position, the comparison module directly or indirectly compares the voltage of the first end of the second power switch with a first preset voltage during the demagnetization of the transformer, and when the voltage of the first end of the second power switch is lower than the first preset voltage, the comparison module outputs a demagnetization signal indicating that the demagnetization of the transformer is finished; or the comparison module compares the voltage of the control end of the second power switch with a second preset voltage in the demagnetizing period of the transformer, and when the voltage of the control end of the second power switch is lower than the second preset voltage, the comparison module outputs a demagnetizing signal indicating the end of the demagnetization of the transformer.
Preferably, the comparing module comprises a comparator, wherein the in-phase end of the comparator is coupled with a first preset voltage, the inverting end of the comparator is directly or indirectly coupled with the voltage of the first end of the second power switch through a voltage dividing resistor, and when the voltage of the inverting end of the comparator is lower than the voltage of the in-phase end, the comparator outputs a demagnetization signal indicating that demagnetization of the transformer is finished; or the comparison module comprises a comparator, the in-phase end of the comparator is coupled with a second preset voltage, the inverting end of the comparator is coupled with the voltage of the control end of the second power switch, and when the voltage of the inverting end of the comparator is lower than the voltage of the in-phase end, the comparator outputs a demagnetizing signal indicating that the demagnetization of the transformer is finished.
Preferably, the auxiliary winding and the main winding of the transformer have identical ends at different positions, the comparison module directly or indirectly compares the voltage of the first end of the second power switch with a first preset voltage during the demagnetization of the transformer, and when the voltage of the first end of the second power switch is higher than the first preset voltage, the comparison module outputs a demagnetization signal indicating that the demagnetization of the transformer is finished; or the comparison module compares the voltage of the control end of the second power switch with a second preset voltage in the demagnetizing period of the transformer, and when the voltage of the control end of the second power switch is higher than the second preset voltage, the comparison module outputs a demagnetizing signal indicating that the demagnetization of the transformer is finished.
Preferably, the comparing module comprises a comparator, wherein the in-phase end of the comparator is coupled with a first preset voltage, the inverting end of the comparator is directly or indirectly coupled with the voltage of the first end of the second power switch through a voltage dividing resistor, and when the voltage of the inverting end of the comparator is higher than the voltage of the in-phase end, the comparator outputs a demagnetization signal indicating that demagnetization of the transformer is finished; or the comparison module comprises a comparator, the in-phase end of the comparator is coupled with a second preset voltage, the inverting end of the comparator is coupled with the voltage of the control end of the second power switch, and when the voltage of the inverting end of the comparator is higher than the voltage of the in-phase end, the comparator outputs a demagnetizing signal indicating that the demagnetization of the transformer is finished.
In a second aspect, an embodiment of the present invention provides a power supply system, including the demagnetization detecting circuit according to any of the first aspects.
Preferably, the power supply system includes an input capacitor, an output capacitor coupled in parallel with a load, a demagnetization detection circuit, a control module, and a power stage including a main stage winding, a freewheel module, and a first power switch.
Preferably, the power supply system comprises an input capacitor, an output capacitor coupled in parallel with a load, a demagnetization detection 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 snubber circuit includes a snubber diode and a snubber capacitor.
Preferably, before the control module of the power supply system controls the first power switch to switch from the off state to the on state, the control module controls the second power switch in the demagnetization detection circuit to conduct for a pulse time to charge the auxiliary winding, and after the voltage across the two ends of the first power switch is reduced from the initial first potential to the lower second potential through the coupling relation of the transformer, the control module controls the first power switch to switch from the off state to the on state, so that the switching loss of the power supply system is lower.
Preferably, the power supply system comprises a driving chip, wherein the driving chip at least comprises a second power switch, a comparison module and a control module; the comparison module at least comprises a comparator, one input end of the comparator is directly or indirectly coupled with one node of the second power switch, and the comparator outputs a demagnetizing signal which indicates that demagnetization of the transformer is finished.
In a third aspect, an embodiment of the present invention provides an electronic device, including the demagnetization detecting circuit according to any of the first aspect.
The technology of the invention has the following advantages:
based on the demagnetization detection circuit, the auxiliary winding for reducing the switching loss of the power supply system is multiplexed, and the reliability of detection of the demagnetization state of the power supply system is improved through detection of the second power switch which is coupled with the auxiliary winding in series.
Drawings
FIG. 1 is a simplified block diagram of a demagnetization detection circuit according to an embodiment of the present invention;
FIGS. 2-4 illustrate a power supply system with a demagnetization detection circuit according to an embodiment of the present invention;
fig. 5a to 5b are simplified circuits of the demagnetization detecting module according to the embodiment of the present 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.
[ reference numerals description ]
11: first power supply system
110: demagnetizing detection circuit
1101: detection module
1102: comparison module
11021: comparator with a comparator circuit
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
[ symbolic description ]
MP: first power switch
MA: second power switch
GP: first control signal
GA: second control signal
Vds: cross-over pressure
SWA: detecting voltage
ZXC: demagnetizing signal
Cgd: parasitic gate-drain capacitance
TS: transformer
Lp: main-stage winding
Ls: secondary winding
La: auxiliary winding
Nps: turns ratio
Dlp: absorption diode
Clp: absorption capacitor
VREF1: a first preset voltage
VREF2: a second preset voltage
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, an embodiment of the present invention provides a demagnetization detecting circuit.
In one embodiment, as shown in fig. 1, an embodiment of the present invention provides a demagnetization detecting circuit 110, which is applied to a first power supply system 11 having a transformer TS, an input capacitor CIN, and an output capacitor CO, where the transformer TS has at least an auxiliary winding La and a main winding Lp, and the demagnetization detecting circuit 110 includes: the auxiliary winding La is provided with two ends, wherein the first end is coupled with the input voltage VIN of the first end of the input capacitor CIN or is coupled with the input voltage VIN of the first end of the input capacitor CIN after passing through the capacitor; a detection module 1101 coupled to a second end of the auxiliary winding La, at least comprising a second power switch MA, the detection module 1101 being configured to detect a demagnetized state of the transformer TS; the comparing module 1102 is coupled to the detecting module 1101, and is configured to compare a node voltage of the detecting module 1101 and output a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is completed.
In a second aspect, an embodiment of the present invention provides a power supply system including the demagnetization detecting circuit of the first aspect.
In one embodiment, as shown in fig. 2 for the second power supply system 12, the auxiliary winding La and the main winding Lp of the transformer TS have identical ends in the same position; the second power supply system 12 includes an input capacitance CIN, an output capacitance CO coupled in parallel to a load, a demagnetization detection 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; 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 non-same-name end of the auxiliary winding La is coupled with the first end of the second power switch MA, and the control end of the second power switch MA is coupled with the second control signal GA output by the control module 112; the second end of the output capacitor CO is coupled with the homonymous end of the main stage winding Lp of the transformer TS, the non-homonymous 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 of the first power switch MP is coupled with the first control signal GP output by the control module 112; a second terminal of the freewheel module 121 is coupled to the first terminal of the input capacitance CIN; the control module 112 is coupled to the demagnetizing signal ZXC output by the demagnetizing detection circuit 110.
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, the freewheel module 121 is composed of diodes, and a power supply system including the diodes constitutes an asynchronous rectification structure.
In one embodiment, the freewheel module 121 is composed of a field effect transistor (MOSFET), and a power supply system including the field effect transistor forms a synchronous rectification structure.
In one embodiment, the power supply system further comprises a rectifier bridge, wherein an input end of the rectifier bridge is coupled with the alternating current, and an input capacitor CIN is coupled with an output end of the rectifier bridge and used for bypassing the high-frequency signal; in one embodiment, the input terminal of the power system is directly coupled to the dc input voltage VIN, and the input capacitor CIN is used for bypassing the high frequency signal of the input voltage VIN.
During the period when the first control signal GP output by the control mode 112 is at a high level, the first power switch MP is turned on, the input voltage VIN charges the main winding Lp through the output capacitor CO and the load, the main winding current Ip on the main winding Lp increases linearly, at this time, the voltage drop on the main winding Lp is VIN-VO, and since the auxiliary winding La of the transformer TS and the main winding Lp have the same-name end at the same position, in one embodiment, the first end of the auxiliary winding La is the same-name end of the auxiliary winding La, and the second end of the auxiliary winding La is the non-same-name end; in one embodiment, when the number of turns of the main winding Lp and the auxiliary winding La is the same, the voltage drop across the auxiliary winding La is VIN-VO, during charging of the main winding Lp, the potential of the non-homonymous terminal of the auxiliary winding La is VIN- (VIN-VO) =vo, and the potential of the non-homonymous terminal of the main winding is approximately zero; after the first control signal GP output by the control module 112 changes from high level to low level, the first power switch MP is turned off, the primary winding current Ip on the primary winding Lp is linearly reduced by the freewheel module 121 to perform freewheel demagnetization, the voltage drop on the primary winding Lp is-VO, the voltage drop on the auxiliary winding La is-VO, during the demagnetization discharge of the primary winding Lp, the potential of the non-homonymous end of the auxiliary winding La is vin+vo, the potential of the non-homonymous end of the primary winding is approximately VIN (neglecting the conduction voltage drop of the freewheel module 121), after the discharge of the primary winding Lp is completed, the primary winding Lp resonates with the parasitic capacitor Coss at the first end of the first power switch MP, the potential of the non-homonymous end of the primary winding Lp is reduced from the resonance of the first potential VIN, and the potential of the non-homonymous end of the auxiliary winding La is also reduced from the resonance of vin+vo due to the coupling effect of the transformer TS. The first terminal of the second power switch MA in the detection module 1101 coupled to the auxiliary winding La is coupled to the non-homonymous terminal of the auxiliary winding La, so that the voltage at the non-homonymous terminal of the auxiliary winding La is also the voltage at the first terminal of the second power switch MA, which is also coupled to the control terminal of the second power switch MA through the parasitic gate-drain capacitance Cgd of the second power switch MA.
The comparison module 1102 coupled to the detection module 1101 directly compares the voltage SWA of the first end of the second power switch MA with the first preset voltage VREF1 during the demagnetization discharge of the transformer TS, and when the voltage SWA of the first end of the second power switch MA is lower than the first preset voltage VREF1, the comparison module 1102 outputs a demagnetization signal ZXC indicating that the demagnetization of the transformer TS is finished; in one embodiment, to avoid the high voltage at the first end of the second power switch MA, during the demagnetization discharge of the transformer TS, the voltage SWA at the first end of the second power switch MA is indirectly compared with the first preset voltage VREF1 through the resistor voltage division to realize the detection of the demagnetization signal ZXC of the transformer TS. In one embodiment, the comparing module 1102 compares the voltage of the control terminal of the second power switch MA with the second preset voltage VREF2 during the demagnetization of the transformer TS, and when the voltage of the control terminal of the second power switch MA is lower than the second preset voltage VREF2, the comparing module 1102 outputs the demagnetization signal ZXC indicating that the demagnetization of the transformer TS is completed.
In one embodiment, the comparing module 1102 includes a comparator 11021, as shown in fig. 5a, the non-inverting terminal of the comparator 11021 is coupled to the first preset voltage VREF1, the inverting terminal is directly or indirectly coupled to the voltage of the first terminal of the second power switch MA through a voltage dividing resistor, and when the voltage of the inverting terminal of the comparator 11021 is lower than the voltage of the non-inverting terminal, the comparator 11021 outputs a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is finished.
In one embodiment, the comparing module 1102 includes a comparator 11021, as shown in fig. 5b, the non-inverting terminal of the comparator 11021 is coupled to the second preset voltage VREF2, the inverting terminal is coupled to the voltage of the control terminal of the second power switch MA, and when the voltage of the inverting terminal of the comparator 11021 is lower than the voltage of the non-inverting terminal, the comparator 11021 outputs a demagnetizing signal ZXC indicating that the demagnetization of the transformer TS is finished.
In one embodiment, before the control module 112 controls the first power switch MP to switch from the off state to the on state, the second power switch MA in the demagnetization detecting circuit 110 is controlled by the second control signal GA to charge the auxiliary winding La by leading the second power switch MA to a pulse time, and after the voltage across Vds across the first power switch MP is reduced from the initial first potential VIN to the lower second potential (the second potential is lower than the first potential VIN, in one embodiment, the second potential is approximately zero), the control module 112 controls the first power switch MP to switch from the off state to the on state, so that the switching loss of the second power system 12 is lower.
In one embodiment, the second power system 12 includes a driver chip including at least a second power switch MA, a comparison module 1102, and a control module 112; the comparison module 1102 at least includes a comparator 11021, an input terminal of the comparator 11021 is directly or indirectly coupled to a node of the second power switch MA, and the comparator 11021 outputs a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is finished.
In one embodiment, as shown in the third power supply system 13 of fig. 3, the auxiliary winding La and the main winding Lp of the transformer TS have identical terminals at different positions; the third power supply system 13 comprises an input capacitor CIN, an output capacitor CO coupled in parallel to a load, a demagnetization detection circuit 110, a control module 112 and a third power stage 130, the third power stage 130 comprising a main stage winding Lp, a freewheel module 121 and a first power switch MP; 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 non-same-name end of the auxiliary winding La is coupled with the first end of the second power switch MA, and the control end of the second power switch MA is coupled with the second control signal GA output by the control module 112; the second end of the output capacitor CO is coupled with a non-homonymous end of the main stage winding Lp of the transformer TS, the homonymous end of the main stage winding Lp is coupled with a first end of the first power switch MP and a first end of the follow current module 121, and a control end of the first power switch MP is coupled with a first control signal GP output by the control module 112; a second terminal of the freewheel module 121 is coupled to the first terminal of the input capacitance CIN; the control module 112 is coupled to the demagnetizing signal ZXC output by the demagnetizing detection circuit 110.
The main difference of the third power supply system 13 compared to the second power supply system 12 shown in fig. 2 is that the auxiliary winding La and the main stage winding Lp of the transformer TS in the third power supply system 13 have the same name ends in different positions.
During the period when the first control signal GP output by the control mode 112 is at a high level, the first power switch MP is turned on, the input voltage VIN charges the primary winding Lp through the output capacitor CO, the primary winding current Ip on the primary winding Lp increases linearly, at this time, the voltage drop on the primary winding Lp is VIN-VO, the auxiliary winding La of the transformer TS and the primary winding Lp have opposite-position homonymous ends, in one embodiment, the first end of the auxiliary winding La is the homonymous end of the auxiliary winding La, and the second end of the auxiliary winding La is the non-homonymous end; in one embodiment, when the number of turns of the main winding Lp and the auxiliary winding La is the same, the voltage drop across the auxiliary winding La is- (VIN-VO), during charging of the main winding Lp, the potential of the non-homonymous terminal of the auxiliary winding La is vin+ (VIN-VO) =2vin-VO, and the potential of the non-homonymous terminal of the main winding is approximately zero; after the first control signal GP output by the control module 112 changes from high level to low level, the first power switch MP is turned off, the primary winding current Ip on the primary winding Lp linearly decreases by the freewheel module 121 performing the freewheel demagnetization discharge, the voltage drop on the primary winding Lp is-VO, and the voltage drop on the auxiliary winding La is VO, so that during the period of the main winding Lp demagnetization discharge, the potential of the non-homonymous end of the auxiliary winding La is VIN-VO, the potential of the homonymous end of the primary winding is approximately VIN (ignoring the conduction voltage drop of the freewheel module 121), after the discharge of the primary winding Lp is completed, the potential of the homonymous end of the primary winding Lp decreases from the first potential VIN resonance, and the potential of the non-homonymous end of the auxiliary winding La increases from the first potential VIN-VO resonance due to the coupling effect of the transformer TS. The first terminal of the second power switch MA in the detection module 1101 coupled to the auxiliary winding La is coupled to the non-homonymous terminal of the auxiliary winding La, so that the voltage at the non-homonymous terminal of the auxiliary winding La is also the voltage at the first terminal of the second power switch MA, which is also coupled to the control terminal of the second power switch MA through the parasitic gate-drain capacitance Cgd of the second power switch MA.
The comparison module 1102 coupled to the detection module 1101 directly compares the voltage SWA of the first end of the second power switch MA with the first preset voltage VREF1 during the demagnetization discharging period of the transformer TS, and when the voltage SWA of the first end of the second power switch MA is higher than the first preset voltage VREF1, the comparison module 1102 outputs a demagnetization signal ZXC indicating that the demagnetization of the transformer TS is finished; in one embodiment, to avoid the high voltage at the first end of the second power switch MA, during the demagnetization discharge of the transformer TS, the voltage SWA at the first end of the second power switch MA is indirectly compared with the first preset voltage VREF1 through the resistor voltage division to realize the detection of the demagnetization signal ZXC of the transformer TS. In one embodiment, the comparing module 1102 compares the voltage of the control terminal of the second power switch MA with the second preset voltage VREF2 during the demagnetization of the transformer TS, and when the voltage of the control terminal of the second power switch MA is higher than the second preset voltage VREF2, the comparing module 1102 outputs the demagnetization signal ZXC indicating that the demagnetization of the transformer TS is completed.
In one embodiment, the comparing module 1102 includes a comparator 11021, as shown in fig. 5a, the non-inverting terminal of the comparator 11021 is coupled to the first preset voltage VREF1, the inverting terminal is directly or indirectly coupled to the voltage of the first terminal of the second power switch MA through a voltage dividing resistor, and when the voltage of the inverting terminal of the comparator 11021 is higher than the voltage of the non-inverting terminal, the comparator 11021 outputs a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is finished.
In one embodiment, the comparing module 1102 includes a comparator 11021, as shown in fig. 5b, the non-inverting terminal of the comparator 11021 is coupled to the second preset voltage VREF2, the inverting terminal is coupled to the voltage of the control terminal of the second power switch MA, and when the voltage of the inverting terminal of the comparator 11021 is higher than the voltage of the non-inverting terminal, the comparator 11021 outputs the demagnetizing signal ZXC indicating that the demagnetization of the transformer TS is finished.
In one embodiment, the control module 112 outputs the second control signal GA, before controlling the first power switch MP to switch from the off state to the on state, controls the second power switch MA in the demagnetization detecting circuit 110 to charge the auxiliary winding La by leading a pulse time, and after the voltage across Vds across the first power switch MP is reduced from the initial first potential VIN to the lower second potential (the second potential is lower than the first potential VIN, in one embodiment, the second potential is approximately zero), the control module 112 controls the first power switch MP to switch from the off state to the on state, so that the switching loss of the third power system 13 is lower.
In one embodiment, the third power system 13 includes a driver chip including at least a second power switch MA, a comparison module 1102, and a control module 112; the comparison module 1102 at least includes a comparator 11021, an input terminal of the comparator 11021 is directly or indirectly coupled to a node of the second power switch MA, and the comparator 11021 outputs a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is finished.
In one embodiment, as shown in the fourth power supply system 14 of fig. 4, the auxiliary winding La and the main winding Lp of the transformer TS have identical-name ends at the same position; the fourth power supply system 14 includes an input capacitor CIN, an output capacitor CO coupled in parallel to a load, a demagnetization detection circuit 110, a control module 112, an absorption module 141, and a fourth power stage 140, the fourth power stage 140 including a primary winding Lp, a secondary winding La, a freewheel module 121, and a first power switch MP; 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 first end of the absorption capacitor Clp is coupled with the same-name end of the auxiliary winding Lp and the cathode of the absorption diode Dlp, the non-same-name end of the auxiliary winding La is coupled with the first end of the second power switch MA, and the control end of the second power switch MA is coupled with the second control signal GA output by the control module 112; the non-homonymous 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, and the control end of the first power switch MP is coupled with a first control signal GP output by 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 comparison module 1102 compares the voltage of one node of the detection module 1101 and outputs a demagnetizing signal ZXC indicating the end of demagnetization of the transformer TS; the control module 112 is coupled to the demagnetizing signal ZXC output by the demagnetizing detection circuit 110.
During the period when the first control signal GP output by the control mode 112 is at the high level, the input voltage VIN charges the main winding Lp when the first power switch MP is turned on, and at this time, the voltage drop on the main winding Lp is approximately VIN (neglecting the conduction voltage drop of the first power switch MP), and in one embodiment, the number of turns of the main winding Lp and the auxiliary winding La is the same, and the voltage drop on the auxiliary winding La is also kept at VIN through the coupling relationship of the transformer TS; 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 and the secondary winding Ls), so the voltage at the first end of the second power switch MA is equal or approximately equal to Nps times the load voltage VO; when the first power switch MP is turned off, the load voltage VO on the output capacitor CO discharges the secondary winding Ls, which is equivalent to the voltage drop on the primary winding Lp being approximately-Nps ×vo (neglecting the on-voltage drop of the snubber diode Dlp), so that during the discharge of the secondary winding Ls, the voltage drop on the second power switch MA is (vin+ Nps ×vo) - (-Nps ×vo) =vin+2nps×vo, so that the voltage at the first end of the second power switch MA is equal or approximately equal to vin+2nps×vo; after the demagnetization of the transformer TS is finished, LC resonance occurs between the main winding Lp and the parasitic capacitor Coss at the first end of the first power switch MP, so that the cross voltage Vds resonance at the two ends of the first power switch MP is reduced, the voltage at the first end of the first power switch MP starts to be reduced from the first potential vin+ Nps ×vo to a lower second potential, and the voltage at the first end of the second power switch MA also is reduced from the high potential vin+2mps×vo resonance through the coupling relation of the transformer TS. The first terminal of the second power switch MA in the detection module 1101 coupled to the auxiliary winding La is coupled to the non-homonymous terminal of the auxiliary winding La, so that the voltage at the non-homonymous terminal of the auxiliary winding La is also the voltage at the first terminal of the second power switch MA, which is also coupled to the control terminal of the second power switch MA through the parasitic gate-drain capacitance Cgd of the second power switch MA.
The comparison module 1102 coupled to the detection module 1101 directly compares the voltage SWA of the first end of the second power switch MA with the first preset voltage VREF1 during the demagnetization discharge of the transformer TS, and when the voltage SWA of the first end of the second power switch MA is lower than the first preset voltage VREF1, the comparison module 1102 outputs a demagnetization signal ZXC indicating that the demagnetization of the transformer TS is finished; in one embodiment, to avoid the high voltage at the first end of the second power switch MA, during the demagnetization discharge of the transformer TS, the voltage SWA at the first end of the second power switch MA is indirectly compared with the first preset voltage VREF1 through the resistor voltage division to realize the detection of the demagnetization signal ZXC of the transformer TS. In one embodiment, the comparing module 1102 compares the voltage of the control terminal of the second power switch MA with the second preset voltage VREF2 during the demagnetization of the transformer TS, and when the voltage of the control terminal of the second power switch MA is lower than the second preset voltage VREF2, the comparing module 1102 outputs the demagnetization signal ZXC indicating that the demagnetization of the transformer TS is completed.
In one embodiment, the comparing module 1102 includes a comparator 11021, as shown in fig. 5a, the non-inverting terminal of the comparator 11021 is coupled to the first preset voltage VREF1, the inverting terminal is directly or indirectly coupled to the voltage of the first terminal of the second power switch MA through a voltage dividing resistor, and when the voltage of the inverting terminal of the comparator 11021 is higher than the voltage of the non-inverting terminal, the comparator 11021 outputs a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is finished.
In one embodiment, the comparing module 1102 includes a comparator 11021, as shown in fig. 5b, the non-inverting terminal of the comparator 11021 is coupled to the second preset voltage VREF2, the inverting terminal is coupled to the voltage of the control terminal of the second power switch MA, and when the voltage of the inverting terminal of the comparator 11021 is higher than the voltage of the non-inverting terminal, the comparator 11021 outputs the demagnetizing signal ZXC indicating that the demagnetization of the transformer TS is finished.
In one embodiment, the second control signal GA output by the control module 112 controls the second power switch MA in the demagnetization detecting circuit 110 to charge the auxiliary winding La by a pulse time before controlling the first power switch MP to switch from the off state to the on state, and after the voltage across Vds across the first power switch MP is reduced from the initial first potential vin+ Nps ×vo to the lower second potential (the second potential is lower than the first potential vin+ Nps ×vo, in one embodiment, the second potential is approximately zero), the control module 112 controls the first power switch MP to switch from the off state to the on state, so that the switching loss of the fourth power system 14 is lower.
In one embodiment, the fourth power system 14 includes a driver chip including at least a second power switch MA, a comparison module 1102, and a control module 112; the comparison module 1102 at least includes a comparator 11021, an input terminal of the comparator 11021 is directly or indirectly coupled to a node of the second power switch MA, and the comparator 11021 outputs a demagnetizing signal ZXC indicating that demagnetization of the transformer TS is finished.
In the description of the embodiment of the present application, the same number of winding turns is adopted for the main winding Lp and the auxiliary winding La of the transformer TS, or the turns ratio of the main winding Lp to the auxiliary winding La is 1, but this is not meant to be a limiting relationship, so that the working principle of the present invention can be described more simply and easily, and the present invention is equally applicable to the main winding Lp and the auxiliary winding La of the transformer TS with different numbers of turns.
In a third aspect, an embodiment of the present invention provides an electronic device, including the demagnetization detecting circuit of the first aspect.
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 demagnetizing detection circuit, the auxiliary winding for reducing the switching loss of the power supply system is multiplexed, and the reliability of detecting the demagnetizing state of the power supply system is improved by detecting the second power switch inside the driving chip of the power supply system.
2) The electronic device of the application multiplexes the auxiliary winding for reducing the switching loss of the power supply system, detects the internal second power switch of the driving chip of the power supply system, and improves the reliability of the detection of the demagnetizing state of the power supply system.
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. A demagnetization detection circuit applied to a power supply system with a transformer, an input capacitor and an output capacitor, wherein the transformer is provided with at least an auxiliary winding and a main winding, and the demagnetization detection circuit comprises:
the auxiliary winding is provided with two ends, and the first end of the auxiliary winding is coupled with the first end of the input capacitor or is coupled with the first end of the input capacitor after passing through the capacitor;
a detection module coupled to the second end of the auxiliary winding, at least comprising a second power switch, the detection module configured to detect a demagnetized state of the transformer;
and the comparison module is coupled with the detection module, and is configured to compare the voltage of one node of the detection module and output a demagnetizing signal which indicates that the demagnetization of the transformer is finished.
2. The demagnetization detecting circuit according to claim 1, wherein the auxiliary winding and the main winding of the transformer have identical-name terminals at the same position, the comparison module directly or indirectly compares the voltage of the first end of the second power switch with a first preset voltage during the demagnetization of the transformer, and when the voltage of the first end of the second power switch is lower than the first preset voltage, the comparison module outputs a demagnetization signal indicating that the demagnetization of the transformer is finished; or the comparison module compares the voltage of the control end of the second power switch with a second preset voltage in the demagnetizing period of the transformer, and when the voltage of the control end of the second power switch is lower than the second preset voltage, the comparison module outputs a demagnetizing signal indicating the end of the demagnetization of the transformer.
3. The demagnetization detecting circuit according to claim 2, wherein the comparing module includes a comparator, the non-inverting terminal of the comparator is coupled to the first preset voltage, the inverting terminal is directly or indirectly coupled to the voltage of the first terminal of the second power switch through the voltage dividing resistor, and when the voltage of the inverting terminal of the comparator is lower than the voltage of the non-inverting terminal, the comparator outputs a demagnetization signal indicating that demagnetization of the transformer is finished; or the comparison module comprises a comparator, the in-phase end of the comparator is coupled with a second preset voltage, the inverting end of the comparator is coupled with the voltage of the control end of the second power switch, and when the voltage of the inverting end of the comparator is lower than the voltage of the in-phase end, the comparator outputs a demagnetizing signal indicating that the demagnetization of the transformer is finished.
4. The demagnetization detecting circuit according to claim 1, wherein the auxiliary winding and the main winding of the transformer have identical terminals at different positions, the comparison module directly or indirectly compares the voltage of the first terminal of the second power switch with a first preset voltage during the demagnetization of the transformer, and when the voltage of the first terminal of the second power switch is higher than the first preset voltage, the comparison module outputs a demagnetization signal indicating that the demagnetization of the transformer is finished; or the comparison module compares the voltage of the control end of the second power switch with a second preset voltage in the demagnetizing period of the transformer, and when the voltage of the control end of the second power switch is higher than the second preset voltage, the comparison module outputs a demagnetizing signal indicating that the demagnetization of the transformer is finished.
5. The demagnetization detecting circuit of claim 4, wherein the comparing module includes a comparator, the non-inverting terminal of the comparator is coupled to the first preset voltage, the inverting terminal is directly or indirectly coupled to the voltage of the first terminal of the second power switch through the voltage dividing resistor, and when the voltage of the inverting terminal of the comparator is higher than the voltage of the non-inverting terminal, the comparator outputs a demagnetization signal indicating that demagnetization of the transformer is finished; or the comparison module comprises a comparator, the in-phase end of the comparator is coupled with a second preset voltage, the inverting end of the comparator is coupled with the voltage of the control end of the second power switch, and when the voltage of the inverting end of the comparator is higher than the voltage of the in-phase end, the comparator outputs a demagnetizing signal indicating that the demagnetization of the transformer is finished.
6. A power supply system comprising the demagnetization detection circuit of any of claims 1 to 5, characterized in that the power supply system comprises an input capacitance, an output capacitance coupled in parallel to a load, the demagnetization detection circuit, a control module, and a power stage comprising a main stage winding, a freewheel module, and a first power switch.
7. A power supply system comprising the demagnetization detection circuit of any of claims 1 to 5, characterized in that the power supply system comprises an input capacitance, an output capacitance coupled in parallel to a load, the demagnetization detection circuit, a control module, a power stage comprising a primary winding and a secondary winding of a transformer, a freewheel module and a first power switch, and an absorption circuit; the snubber circuit includes a snubber diode and a snubber capacitor.
8. The power supply system according to claim 6 or 7, wherein the control module of the power supply system controls the second power switch in the demagnetization detection circuit to conduct for a pulse time to charge the auxiliary winding before controlling the first power switch to switch from the off state to the on state, and controls the first power switch to switch from the off state to the on state after reducing the voltage across the first power switch from the initial first potential to the lower second potential through the coupling relation of the transformer, so that the switching loss of the power supply system is lower.
9. The power supply system according to claim 6 or 7, characterized in that the power supply system comprises a drive chip comprising at least a second power switch, a comparison module and a control module; the comparison module at least comprises a comparator, one input end of the comparator is directly or indirectly coupled with one node of the second power switch, and the comparator outputs a demagnetizing signal which indicates that demagnetization of the transformer is finished.
10. An electronic device comprising the demagnetization detecting circuit according to any of claims 1 to 3.
CN202310251289.3A 2023-03-15 2023-03-15 Demagnetizing detection circuit, power supply system and electronic device Pending CN116317602A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116722720A (en) * 2023-08-10 2023-09-08 恩赛半导体(成都)有限公司 Auxiliary circuit, power supply system and electronic device
CN117200586A (en) * 2023-11-06 2023-12-08 恩赛半导体(成都)有限公司 Auxiliary power supply, power supply system and power supply equipment

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116722720A (en) * 2023-08-10 2023-09-08 恩赛半导体(成都)有限公司 Auxiliary circuit, power supply system and electronic device
CN116722720B (en) * 2023-08-10 2023-10-24 恩赛半导体(成都)有限公司 Auxiliary circuit, power supply system and electronic device
CN117200586A (en) * 2023-11-06 2023-12-08 恩赛半导体(成都)有限公司 Auxiliary power supply, power supply system and power supply equipment
CN117200586B (en) * 2023-11-06 2024-02-06 恩赛半导体(成都)有限公司 Auxiliary power supply, power supply system and power supply equipment

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