CN115967258B

CN115967258B - Power supply circuit, power supply system and electronic device

Info

Publication number: CN115967258B
Application number: CN202310141675.7A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Ensai Semiconductor Chengdu Co ltd
Current assignee: Ensai Semiconductor Chengdu Co ltd
Priority date: 2023-02-21
Filing date: 2023-02-21
Publication date: 2023-05-23
Anticipated expiration: 2043-02-21
Also published as: CN115967258A

Abstract

The invention discloses a power supply circuit, a power supply system and an electronic device, wherein the power supply circuit comprises: the detection module comprises an 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; a power supply capacitor configured to supply a power supply voltage for supplying power; and the power supply module is coupled with the detection voltage and charges the power supply capacitor and supplies power to the outside. The power supply circuit provided by the invention has the advantages of simple structure and high power supply efficiency.

Description

Power supply circuit, power supply system and electronic device

Technical Field

The present invention relates to the field of power conversion technologies, and in particular, to a power supply circuit, a power supply system, and an electronic device.

Background

Basically, each power supply system has its own power supply circuit, especially for the power supply system of the AC-DC power converter, since the bus voltage has a wide variation range, and generally includes the entire voltage range of 85Vac-265Vac, if the power supply system is directly powered by the high-voltage bus voltage to supply power to the driving chip of the power supply system, the power supply efficiency of the entire power supply system is reduced, the temperature of the power supply system is increased, the volume is increased, and the cost is increased, so that improvement is necessary.

Disclosure of Invention

The embodiment of the invention provides a power supply circuit, a power supply system and an electronic device.

In a first aspect, an embodiment of the present invention provides a power supply circuit applied to a power supply system having a transformer, where an auxiliary winding and a main winding of the transformer have identical ends with identical positions, the power supply circuit includes:

a detection module including the auxiliary winding and a second power switch coupled in series with the auxiliary winding, the detection module configured to detect and output a detection voltage;

a power supply capacitor configured to supply a power supply voltage for supplying power;

and the power supply module is coupled with the detection voltage and charges the power supply capacitor and supplies power to the outside.

Preferably, during charging of the primary winding, the detection module outputs the detection voltage at a common terminal of the auxiliary winding and the second power switch, and the detection voltage changes in the same direction as the load voltage or a multiple of the load voltage.

Preferably, the power supply module charges a power supply capacitor and supplies power to the outside during the operation of the power supply system; or the power supply module only charges the power supply capacitor and externally supplies power during the charging of the main-stage winding of the power supply system.

Preferably, the power supply module comprises a high-voltage isolation module and a low-voltage differential regulator; the input end of the high-voltage isolation module is coupled with the detection voltage; the output of the low dropout regulator charges the supply capacitor and supplies power to the outside.

In a second aspect, embodiments of the present invention provide a power supply system comprising any of the power supply circuits of the first aspect.

Preferably, the power supply system further comprises an input capacitor, an output capacitor coupled in parallel with the load, 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 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; the power supply module and the power supply capacitor supply power for the control module.

Preferably, the power supply system further comprises an input capacitor, an output capacitor coupled in parallel with the load, 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 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; the power supply module and the power supply capacitor supply power for the control module.

Preferably, the power supply system further comprises an input capacitor, an output capacitor coupled in parallel with the load, a control module, a power stage and an absorption circuit, wherein the power stage comprises a primary winding and a secondary winding of the 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; the power supply module and the power supply capacitor supply power for the control module.

Preferably, the power supply system comprises a driving chip, and the driving chip at least comprises a power supply module and a control module; the power supply capacitor is positioned outside the driving chip; or the power supply capacitor is positioned in the driving chip; or the power supply capacitor is partially positioned outside the driving chip and partially positioned inside the driving chip.

Preferably, before the control module of the power supply system 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.

In a third aspect, an embodiment of the present invention provides an electronic device, including the power supply circuit according to any one of the first aspects.

The technology of the invention has the following advantages:

according to the power supply circuit and the power supply system provided by the embodiment of the invention, the auxiliary winding for reducing the switching loss of the power supply system is multiplexed, and the voltage related to the load voltage can be indirectly used for providing power for the driving chip of the whole power supply system, so that the volume and the cost of the whole driving power supply are reduced.

The power supply circuit adopting the technology of the invention has smaller area and lower cost.

Drawings

FIG. 1 is a simplified block diagram of a power supply circuit according to an embodiment of the present invention;

FIG. 2 is a power supply system with a power supply circuit according to an embodiment of the present invention;

FIG. 3 is a power supply system with a power supply circuit according to another embodiment of the present invention;

FIG. 4 is a power supply system with a power supply circuit according to yet another embodiment of the present invention;

fig. 5a to 5c are simplified circuits of a power supply module according to an 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.

[ symbolic description ]

11: first power supply system

110: power supply circuit

1101: detection module

1102: power supply module

1103: power supply capacitor

11021: high-voltage isolation module

11022: first low-dropout regulator

11023: second low-dropout regulator

11024: third low-dropout regulator

11025: proportion module

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

VREF1: first reference voltage

VREF2: second reference voltage

VCC: supply 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, as shown in fig. 1, an embodiment of the present invention provides a simplified structure diagram of a power supply 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, and the power supply circuit 110 includes: the detection module 1101 includes an auxiliary winding La and a second power switch MA coupled in series with the auxiliary winding La, and the detection module 1101 is configured to detect and output a detection voltage SWA; a power supply capacitor 1103 configured to supply a power supply voltage VCC for supplying power; the power supply module 1102 is coupled to the detection voltage SWA, charges the power supply capacitor 1103, and supplies power to the outside.

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 main winding Lp, the detection module 1101 outputs a detection voltage SWA at a common terminal of the auxiliary winding La and the second power switch MA, where the detection voltage SWA varies in the same direction as the load voltage VO or a multiple of the load voltage VO, and the same direction variation refers to: when the load voltage VO increases, the detection voltage SWA also increases; when the load voltage VO decreases, the detection voltage SWA also decreases. .

In one embodiment, as shown in fig. 1, the power module 1102 charges the power supply capacitor 1103 and externally supplies power during operation of the first power system 11.

In one embodiment, as shown in FIG. 1, the power module 1102 charges and externally powers the power supply capacitor 1103 only during charging of the primary winding Lp of the power supply system 11.

In a second aspect, embodiments of the present invention also provide a power supply system.

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, a power supply 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 power system further comprises a rectifier bridge, an input terminal of the rectifier bridge is coupled to the alternating current, and an input capacitor CIN is coupled to an output terminal of the rectifier bridge for bypassing the high frequency signal.

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, 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, a power supply 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 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 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 first end of the freewheel 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; 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 power supply module 1102 and the power supply capacitor 1103 supply power to the control module 112.

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 common terminal of the auxiliary winding La and the second power switch MA is equal or approximately equal to the load voltage VO; when the first power switch MP is turned off, the load voltage VO on the output capacitor CO discharges the main winding Lp, at this time, the voltage drop on the main winding Lp is approximately-VO, and under the condition that the turns of the main winding Lp and the auxiliary winding La are the same or approximately the same, the voltage drop on the auxiliary winding La is also kept to be-VO or approximately equal to-VO through the coupling relation of the transformer T1; during the discharging period 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 common terminal of the auxiliary winding La and the second power switch MA is equal or approximately equal to the voltage drop across the second power switch MA; the detection voltage SWA changes in the same direction as the load voltage VO regardless of whether the main stage winding Lp is in the charging period or the discharging period, and when the load voltage VO increases, the detection voltage SWA also increases in the same direction; the power supply module 1102 is coupled to the detection voltage SWA, and generates a power supply voltage VCC to charge and supply the power supply capacitor 1103.

In one embodiment, as shown in fig. 1, the first power system 11 further includes a driver chip, and the driver chip includes at least a power supply module 1102 and a control module 112.

In one embodiment, as shown in fig. 1, the supply capacitor 1103 of the first power supply system 11 is external to the driver chip.

In one embodiment, as shown in fig. 1, the power supply capacitor 1103 of the first power supply system 11 is integrated inside the driver chip;

in one embodiment, as shown in fig. 1, the power supply capacitor 1103 of the first power supply system 11 is partially located outside the driver chip and partially integrated inside the driver chip.

In one embodiment, as shown in fig. 2, the power module 1102 charges and externally powers the power capacitor 1103 during operation of the second power system 12; during charging of the main stage winding Lp of the power supply system 12, the detection voltage SWA is equal or approximately equal to the load voltage VO; during discharge of the main stage winding Lp of the power supply system 12, the detection voltages SWA and vin+vo are equal or approximately equal.

In one embodiment, as shown in FIG. 2, the power module 1102 charges and externally powers the power supply capacitor 1103 only during charging of the primary winding Lp of the power supply system 12. At this time, the detected voltage SWA is equal to or approximately equal to the load voltage VO, and compared with the conventional technology, which directly obtains power from a bus voltage in a very wide range, the relatively stable load voltage VO has lower power supply loss and a smaller variation range.

In one embodiment, as shown in fig. 3, the third power supply system 13 includes an input capacitance CIN, an output capacitance CO coupled in parallel to a load, a power supply 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; 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 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 second end of the input capacitor CIN is coupled with the ground, 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 power supply module 1102 and the power supply capacitor 1103 supply power to the control module 112; 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.

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; when the first power switch MP is turned off, the load voltage VO on the output capacitor CO discharges the main stage winding Lp, at this time, the voltage drop on the main stage winding Lp is approximately-VO, and during the discharging period of the main stage winding Lp, the voltage drop on the second power switch MA is (vin+vo) - (-VO) =vin+2vo, so the detection voltage SWA output by the common terminal of the auxiliary winding La and the second power switch MA is equal or approximately equal to the voltage drop on the second power switch MA; the detection voltage SWA changes in the same direction as the load voltage VO regardless of whether the main stage winding Lp is charged or discharged, and increases in the same direction as the load voltage VO increases.

In contrast to the power supply circuit 110 of the second power supply system 12, the power supply circuit 110 in the third power supply system 13 charges and externally supplies power to the power supply capacitor 1103 during operation of the third power supply system 13; or the power supply module 1102 charges and externally supplies power to the power supply capacitor 1103 only during charging of the main stage winding Lp of the third power supply system 13.

The third power system 13 further includes a driving chip, which at least includes a power supply module 1102 and a control module 112; the power supply capacitor 1103 is positioned outside the driving chip; or the power supply capacitor 1103 is positioned inside the driving chip; or the supply capacitor 1103 is partially located outside the driver chip and partially located inside the driver chip.

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, a power supply 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; 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 first end of the absorption capacitor Clp is coupled with the same-name end of the auxiliary winding La and the cathode of the absorption diode Dlp, 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, 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 power supply module 1102 and the power supply capacitor 1103 supply power to the control module 112; 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.

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 that 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; 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 detection voltage SWA output by the common terminal of the auxiliary winding La and the second power switch MA is equal or approximately equal to the voltage drop on the second power switch MA; the detection voltage SWA changes in the same direction as the load voltage VO regardless of whether the main stage winding Lp is charged or discharged, and increases in the same direction as the load voltage VO increases.

In contrast to the power supply circuit 110 of the second power supply system 12, the power supply circuit 110 in the fourth power supply system 14 charges and externally supplies power to the power supply capacitor 1103 during operation of the fourth power supply system 14; or the power supply module 1102 charges and externally supplies power to the power supply capacitor 1103 only during charging of the primary winding Lp of the fourth power supply system 14.

The fourth power system 14 further includes a driver chip including at least a power module 1102 and a control module 112; the power supply capacitor 1103 is positioned outside the driving chip; or the power supply capacitor 1103 is positioned inside the driving chip; or the supply capacitor 1103 is partially located outside the driver chip and partially located inside the driver chip.

In the above embodiments, in order to conveniently, more clearly and simply describe the working principle of the present invention, the description only exemplifies 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 actual implementation process, the number of turns of the main winding Lp and the auxiliary winding La of the transformer T1 may be kept different, but the working principle of the present invention is not affected.

In one embodiment, as shown in fig. 5a, an embodiment of a power supply module 1102 is illustrated, where the power supply module 1102 in fig. 5a includes a high voltage isolation module 11021 and a first low voltage differential regulator 11022, the high voltage isolation module 11021 is used to isolate the high voltage of the detection voltage SWA, and the high voltage isolation module 11021 is implemented by a depletion field effect transistor or a junction field effect transistor; the first low dropout regulator 11022 is coupled to the first reference voltage VREF1 and outputs a supply voltage VCC equal to the first reference voltage VREF 1;

in one embodiment, as shown in fig. 5b, the power supply module 1102 in fig. 5b includes a high voltage isolation module 11021, a second low voltage differential regulator 11023, and a proportion module 11025, wherein the high voltage isolation module 11021 is used for isolating the high voltage of the detection voltage SWA, and the high voltage isolation module 11021 is implemented by a depletion field effect transistor or a junction field effect transistor; the second low dropout regulator 11023 is coupled to the second reference voltage VREF2 and outputs a supply voltage VCC proportional to the second reference voltage VREF2 for regulation by the scaling module 11025

In one embodiment, as shown in fig. 5c, fig. 5c includes a high voltage isolation module 11021 and a third low voltage differential regulator 11024, and fig. 5c is different from fig. 5a in that the input terminal of the third low voltage differential regulator 11024 is further coupled to the signal of the control terminal GATE of the first power switch MP, so as to control the third low voltage differential regulator 11024 to charge and externally supply the power supply capacitor 1103 only during the charging of the main winding Lp of the transformer T1.

The low dropout regulator in the above embodiments belongs to the prior art, and the present specification will not be described in detail.

In a third aspect, an embodiment of the present invention further provides an electronic device, including the power supply 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) The power supply circuit of the utility model has the advantages of multiplexing the auxiliary winding that reduces the switching loss of a power supply system to can indirectly let the load voltage provide power for the driving chip of the whole power supply system, reduce the volume and the cost of the whole driving power supply, improve the power supply efficiency of a voltage system.

2) The electronic device provided by the application multiplexes the auxiliary winding for reducing the switching loss of the power supply system, and can indirectly enable the load voltage to provide power for the driving chip of the whole power supply system, thereby reducing the volume and the cost of the whole driving power supply and improving the power supply efficiency of the voltage 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

1. A power supply circuit for use in a power supply system having a transformer with auxiliary windings and primary windings having identical ends in identical positions, the power supply circuit comprising:

the detection module comprises an auxiliary winding and a second power switch coupled in series with the auxiliary winding, wherein the homonymous end of the auxiliary winding is coupled with the first end of the input capacitor or coupled with the first end of the input capacitor after passing through a capacitor, the non-homonymous end of the auxiliary winding is coupled with the first end of the second power switch, the second end of the second power switch is coupled with the ground, and the detection module is configured to detect and output a detection voltage at the first end of the second power switch;

2. The power supply circuit of claim 1, wherein the detection module outputs the detection voltage at a common terminal of the auxiliary winding and the second power switch during charging of the primary winding, the detection voltage varying in a same direction as the load voltage or a multiple of the load voltage.

3. The power supply circuit of claim 1, wherein the power supply module charges a power supply capacitor and externally supplies power during operation of the power supply system; or the power supply module only charges the power supply capacitor and externally supplies power during the charging of the main-stage winding of the power supply system.

4. The power supply circuit of claim 1, wherein the power supply module comprises a high voltage isolation module and a low voltage differential regulator; the input end of the high-voltage isolation module is coupled with the detection voltage; the output of the low dropout regulator charges the supply capacitor and supplies power to the outside.

5. A power supply system comprising the power supply circuit of any one of claims 1 to 4, further comprising an input capacitance, an output capacitance coupled in parallel with a load, a control module, and a power stage comprising 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 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; the power supply module and the power supply capacitor supply power for the control module.

6. A power supply system comprising the power supply circuit of any one of claims 1 to 4, further comprising an input capacitance, an output capacitance coupled in parallel with a load, a control module, and a power stage comprising 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 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; the power supply module and the power supply capacitor supply power for the control module.

7. A power supply system comprising the power supply circuit of any one of claims 1 to 4, further comprising an input capacitance, an output capacitance coupled in parallel to a load, a control module, a power stage comprising a primary and secondary windings of a transformer, a freewheel module and a first power switch, and an absorption circuit; 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; the power supply module and the power supply capacitor supply power for the control module.

8. The power supply system according to any one of claims 5 to 7, characterized in that the power supply system comprises a drive chip comprising at least a power supply module and a control module; the power supply capacitor is positioned outside the driving chip; or the power supply capacitor is positioned in the driving chip; or the power supply capacitor is partially positioned outside the driving chip and partially positioned inside the driving chip.

9. The power supply system according to any one of claims 5 to 7, wherein the control module of the power supply system controls the second power switch in the detection module to be turned on for a pulse time to charge the auxiliary winding before the first power switch is turned on, and controls the first power switch to be turned on after the voltage across the first power switch is reduced to zero or approximately zero by the coupling relationship of the transformer.

10. An electronic device comprising the power supply circuit of any one of claims 1 to 4.