CN117097139A - Auxiliary circuit, power supply system and power supply device - Google Patents

Auxiliary circuit, power supply system and power supply device Download PDF

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Publication number
CN117097139A
CN117097139A CN202311339352.5A CN202311339352A CN117097139A CN 117097139 A CN117097139 A CN 117097139A CN 202311339352 A CN202311339352 A CN 202311339352A CN 117097139 A CN117097139 A CN 117097139A
Authority
CN
China
Prior art keywords
power switch
power supply
winding
auxiliary
power
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202311339352.5A
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Chinese (zh)
Inventor
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 CN202311339352.5A priority Critical patent/CN117097139A/en
Publication of CN117097139A publication Critical patent/CN117097139A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H02M1/322—Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
    • 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
    • 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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • 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
    • H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
    • 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

Abstract

The invention discloses an auxiliary circuit, a power supply system and a power supply device, wherein the auxiliary circuit is applied to the power supply system with a transformer and an X capacitor, the transformer is at least provided with an auxiliary winding and a main-stage winding, and the auxiliary circuit comprises: the device comprises a sampling module, an auxiliary winding and an auxiliary module; by controlling the state of the second power switch, the auxiliary circuit can at least enable the X capacitor of the power supply system to discharge rapidly when the power supply system is powered down. Compared with the prior art, the invention improves the efficiency of the power supply system.

Description

Auxiliary circuit, power supply system and power supply device
Technical Field
The invention relates to the technical field of power conversion, in particular to an auxiliary circuit, a power supply system and a power supply device.
Background
In order to improve electromagnetic interference EMI characteristics of a switching power supply, a filter network needs to be added to an ac input end in front of a rectifier bridge of the switching power supply, an X capacitor is an important component element in the switching power supply, and the X capacitor can effectively filter differential mode interference from bus ac voltage. In the prior art, the common practice of discharging the X capacitor is to connect the resistor in parallel to the X capacitor, and the mode can bring larger loss when the switching power supply works normally, and particularly, in the market environment pursuing low standby power consumption at present, the mode of discharging the resistor in parallel is difficult to meet the requirements of quick discharging of the X capacitor and low standby power consumption of the switching power supply. There is a need to improve upon the deficiencies in the prior art.
Disclosure of Invention
In a first aspect, the present invention provides an auxiliary circuit for use in a power supply system having a transformer and an X-capacitor, the transformer having at least an auxiliary winding and a primary winding, the auxiliary circuit comprising:
the sampling module is coupled with the X capacitor, and is configured to sample the voltage on the X capacitor and output the sampled voltage;
an auxiliary winding having two ends, wherein a first end is coupled to the sampling voltage or coupled to the sampling voltage after passing through a capacitor;
an auxiliary module coupled to a second end of the auxiliary winding, including at least a second power switch;
and by controlling the state of the second power switch, the auxiliary circuit enables the X capacitor of the power supply system to be rapidly discharged when the power supply system is powered down.
Preferably, the auxiliary circuit is further capable of supplying an electric voltage to the outside, or detecting a demagnetizing state of the transformer and outputting a demagnetizing signal indicating the end of demagnetization of the transformer.
Preferably, the sampling module comprises a first sampling diode, a second sampling diode and a holding capacitor, wherein the anode of the first sampling diode is coupled with the first end of the X capacitor, the anode of the second sampling diode is coupled with the second end of the X capacitor, the cathode of the first sampling diode and the cathode of the second sampling diode are coupled with the holding capacitor, and the sampling voltage is generated on the holding capacitor.
Preferably, the auxiliary module has at least two ports, a first port is coupled to the second end of the auxiliary winding, and a second port is coupled to a second control signal, and the second control signal controls on and off of the second power switch.
Preferably, the auxiliary module comprises a second power switch and a power supply capacitor, a first end of the second power switch is coupled with a first port of the auxiliary module, a control end of the second power switch is coupled with a second port of the auxiliary module, a second end of the second power switch is coupled with the power supply capacitor and outputs power supply voltage to supply power outwards, and when a power supply system is powered down, the second power switch transfers energy on the X capacitor to the power supply capacitor to generate power supply voltage to supply power outwards, and meanwhile rapid discharging of the X capacitor is realized; or (b)
The auxiliary module comprises a second power switch, a normally-on switch, a power supply capacitor and a detection module, wherein a first end of the normally-on switch is coupled with a first port of the auxiliary module, a second end of the normally-on switch is coupled with a first end of the second power switch, a control end of the normally-on switch is coupled with the detection module, and the detection module outputs a demagnetizing signal indicating the demagnetization of the transformer through detecting the control end of the normally-on switch; the control end of the second power switch is coupled with a second port of the auxiliary module, the second end of the second power switch is coupled with the power supply capacitor and outputs power supply voltage to supply power to the outside, and when the power supply system is powered down, the second power switch and the normally-on switch transfer the energy on the X capacitor to the power supply capacitor to generate the power supply voltage to supply power to the outside, and meanwhile the X capacitor is rapidly discharged.
Preferably, the auxiliary circuit turns on a part or all of a pulse time before the primary winding of the transformer starts to charge, so that current flowing through the secondary power switch flows through the auxiliary winding.
Preferably, the primary winding of the transformer is connected in series with the first power switch, the auxiliary winding and the primary winding have the same-name ends at the same position, and the second power switch is turned on for a part or all of a pulse time before the first power switch is switched from an off state to an on state, current flows into the auxiliary winding, and after the voltage across the two ends of the first power switch is reduced from a first potential when the first power switch is turned off to a second potential lower than the first potential when the first power switch is turned off through a coupling relation between the primary winding and the auxiliary winding of the transformer, the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower; or (b)
The main-stage winding and the first power switch of the transformer are connected in series, the auxiliary winding and the main-stage winding have the same-name ends at opposite positions, the second power switch is conducted in a first period of one pulse time before the first power switch is switched from an off state to an on state, current flows into the auxiliary winding, and the voltage across the two ends of the first power switch rises from the potential when the first power switch is turned off to a first potential through the coupling relation between the main-stage winding and the auxiliary winding of the transformer; in a second period of one pulse time before the first power switch is switched from the off state to the on state, the second power switch is turned off, and after the voltage across the two ends of the first power switch is reduced from the first potential to a second potential which is lower through the coupling relation between the main winding and the auxiliary winding of the transformer, the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower.
In a second aspect, the present invention provides a power supply system, at least comprising the auxiliary circuit of any one of the first aspects, the power supply system further comprising an input capacitor, an output capacitor, a control module and a power stage; the power stage at least comprises a main stage winding of the transformer, a first power switch and a follow current module, wherein a first control signal output by the control module is coupled with a control end of the first power switch to control the on and off of the first power switch; the second control signal output by the control module is coupled with the control end of the second power switch and controls the on and off of the second power switch; the connection relation between the power level and the input capacitor and the output capacitor can be combined to form any one of a buck power supply system, a boost power supply system, a flyback power supply system and a boost power supply system.
Preferably, the control module controls the second power switch in the auxiliary circuit to conduct for a part or all of a pulse time before the first power switch is switched from the off state to the on state, so that the current flowing through the second power switch flows through the auxiliary winding.
Preferably, the auxiliary winding and the main winding of the transformer of the power supply system have the same-name ends at the same position, and when a part or all of pulse time is needed before the first power switch is switched from the off state to the on state, the second power switch is switched on, current flows into the auxiliary winding, and through the coupling relation between the main winding and the auxiliary winding of the transformer, the voltage across the two ends of the first power switch is reduced from a first potential when the first power switch is turned off to a second potential which is lower, and then the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower; or (b)
The auxiliary winding and the main winding of the transformer of the power supply system have the same-name ends at opposite positions, the second power switch is conducted in a first period of one pulse time before the first power switch is switched from an off state to an on state, current flows into the auxiliary winding, and through a coupling relation between the main winding and the auxiliary winding of the transformer, the voltage across the two ends of the first power switch rises from the potential when the first power switch is turned off to a first potential; in a second period of one pulse time before the first power switch is switched from the off state to the on state, the second power switch is turned off, and after the voltage across the two ends of the first power switch is reduced from the first potential to a second potential which is lower through the coupling relation between the main winding and the auxiliary winding of the transformer, the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower.
In a third aspect, the present invention provides a power supply device comprising the power supply system of any one of the second aspects.
The technology of the invention has the following advantages:
based on the auxiliary circuit, the X capacitor of the power supply system can be rapidly discharged when the power supply system is powered down by controlling the state of the second power switch.
Drawings
FIG. 1a is a simplified block diagram of a power supply system of one embodiment of the present invention;
FIG. 1b is a block diagram of a power supply system with auxiliary circuitry according to one embodiment of the invention;
FIG. 1c is a block diagram of a power supply system with auxiliary circuitry according to another embodiment of the present invention;
FIG. 1d is a block diagram of a power supply system with auxiliary circuitry in accordance with yet another embodiment of the present invention;
FIG. 1e is a block diagram of a power supply system with auxiliary circuitry in accordance with yet another embodiment of the present invention;
FIGS. 2 a-2 b are two embodiments of the auxiliary module of the present invention;
FIG. 2c is one embodiment of a detection module of the present invention;
3 a-3 c are schematic waveforms of a portion of nodes of one embodiment of the present invention;
FIG. 4 is a block diagram of a power supply system of another embodiment of the present invention;
fig. 5 is a block diagram of a power supply system according to still another 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.
Description of the reference numerals
11: first power supply system, 100: first power level, 110: first auxiliary circuit, 111: second auxiliary circuit, 12: second power supply system, 120: second power level, 121: freewheel module, 13: third power supply system, 130: third power level, 14: fourth power supply system, 140: fourth power level, 141: absorption circuit, 15: fifth power supply system, 150: fifth power stage, 16: sixth power supply system, 17: and a seventh power supply system.
Symbol description
MP: first power switch, MJ: normally-on switch, MA: second power switch, GP: first control signal, GA: second control signal, coss: parasitic capacitance, CX: x capacitance, DC1: first sampling diode, DC2: second sampling diode, CIC: holding capacitance, CP: supply capacitor, VIC: sampling voltage, VAC: ac voltage, TS: transformer, lp: primary winding, ls: secondary winding, la: auxiliary winding, ip: primary winding current, ia: auxiliary winding current, is: secondary winding current, nps: turns ratio, dlp: absorption diode, clp: absorption capacitance, CIN: input capacitance, CO: output capacitance, VIN: input voltage, VCC: supply voltage, VO: load voltage, cdg: transcapacitive, VREF: reference voltage, SWA: detection signal, ZXC: demagnetizing signal, rsn: pull-down resistors, P1-P4: first port-fourth port, T1-T3: time point, T13: pulse time, T12: during the first period, T23: during the second period, vds: and (5) cross-pressing.
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, the present invention provides an auxiliary circuit. As shown in fig. 1a, a first auxiliary circuit 110 is applied to a first power supply system 11 having a transformer TS and an X-capacitor CX at an ac input, the transformer TS having at least an auxiliary winding La and a main stage winding Lp, the first auxiliary circuit 110 comprising: the sampling module is coupled with the X capacitor CX, and is configured to sample the voltage on the X capacitor CX and output a sampling voltage VIC; an auxiliary winding La having two ends, wherein a first end is coupled to the sampling voltage VIC, and in one embodiment, the first end of the auxiliary winding La is coupled to the sampling voltage VIC through a capacitor; an auxiliary module coupled to a second end of the auxiliary winding La, comprising at least a second power switch MA; by controlling the state of the second power switch MA, the first auxiliary circuit 110 can enable the X capacitor CX of the first power supply system 11 to be rapidly discharged when the first power supply system 11 is powered down; in one embodiment, the first auxiliary circuit 110 is also capable of providing an electrical voltage VCC to externally supply power; in one embodiment, the first auxiliary circuit 110 is further capable of detecting a demagnetizing state of the transformer TS and outputting a demagnetizing signal ZXC indicating the end of demagnetization of the transformer TS.
In one embodiment, as shown in fig. 1a, the sampling module includes a first sampling diode DC1, a second sampling diode DC2, and a holding capacitor CIC, wherein an anode of the first sampling diode DC1 is coupled to a first end of the X capacitor CX, an anode of the second sampling diode DC2 is coupled to a second end of the X capacitor CX, a cathode of the first sampling diode DC1 and a cathode of the second sampling diode DC2 are coupled to the holding capacitor CIC, and a sampling voltage VIC is generated on the holding capacitor CIC.
In one embodiment, as shown in fig. 1a, the auxiliary module has at least two ports, a first port P1 is coupled to the second end of the auxiliary winding La, and a second port P2 is coupled to a second control signal GA, and the second control signal GA controls the second power switch MA to be turned on and off.
In one embodiment, as shown in fig. 2a, the auxiliary module includes a second power switch MA and a supply capacitor CP, a first end of the second power switch MA is coupled to a first port P1 of the auxiliary module, a control end of the second power switch MA is coupled to a second port P2 of the auxiliary module, a second end of the second power switch MA is coupled to the supply capacitor CP and outputs a supply voltage VCC to externally supply power, the supply voltage VCC is equivalent to a third port P3 of the auxiliary module, when the first power supply system 11 is powered down, the second power switch MA is turned on and off under the control of the second control signal GA, firstly, energy on the supply capacitor CIC is transferred to the supply capacitor CP to generate the supply voltage VCC to externally supply power, meanwhile, energy on the X capacitor CX is transferred to the supply capacitor CIC through a first sampling diode DC1 and a second sampling diode DC2, and finally, the first auxiliary circuit 110 transfers the energy on the X capacitor CX to the supply capacitor CP to generate the supply voltage VCC to externally supply power, so as to rapidly discharge the X capacitor CX.
In one embodiment, as shown in fig. 2b, the auxiliary module includes a second power switch MA, a normally-on switch MJ, a supply capacitor CP and a detection module, where a first end of the normally-on switch MJ is coupled to a first port P1 of the auxiliary module, a second end of the normally-on switch MJ is coupled to a first end of the second power switch MA, a control end of the normally-on switch MJ is coupled to the detection module, and the detection module outputs a demagnetization signal ZXC indicating that demagnetization of the transformer TS is completed by detecting a detection signal SWA of the control end of the normally-on switch MJ, where the demagnetization signal ZXC corresponds to a fourth port P4 of the auxiliary module; the control end of the second power switch MA is coupled with a second port P2 of the auxiliary module, when the second control signal GA is at a high level, the second power switch MA is turned on, and when the second control signal GA is at a low level, the second power switch MA is turned off; the second end of the second power switch MA is coupled to the power supply capacitor CP and outputs a power supply voltage VCC to supply power to the outside, the power supply voltage VCC is equivalent to the third port P3 of the auxiliary module, when the first power supply system 11 is powered down, the second power switch MA is turned on and off under the control of the second control signal GA, the energy on the holding capacitor CIC is transferred to the power supply capacitor CP to generate the power supply voltage VCC to supply power to the outside, meanwhile, the energy on the X capacitor CX is transferred to the holding capacitor CIC through the first sampling diode DC1 and the second sampling diode DC2, and finally, the energy is equivalent to the energy on the X capacitor CX transferred to the power supply capacitor CP by the first auxiliary circuit 110 to generate the power supply voltage VCC to supply power to the outside, so that the X capacitor CX is discharged rapidly.
In one embodiment, as shown in fig. 1a, the first auxiliary circuit 110 causes the second power switch MA to be energized for some or all of a pulse time before the primary winding Lp of the transformer TS begins to charge, causing current flowing through the second power switch MA to flow through the auxiliary winding La.
In one embodiment, as shown in fig. 1a, a main winding Lp of a transformer TS is connected in series with a first power switch MP, in one embodiment, an auxiliary winding La and the main winding Lp have identical ends at the same position, a part or all of a pulse time is needed before the first power switch MP is switched from an off state to an on state, a second power switch MA is turned on, current flows into the auxiliary winding La, and after a voltage across Vds of two ends of the first power switch MP is reduced from a first potential when the first power switch MP is turned off to a lower second potential through a coupling relation between the main winding Lp and the auxiliary winding La of the transformer TS, the first power switch MP is switched from the off state to the on state, so that the switching loss of the first power switch MP is lower; in one embodiment, the auxiliary winding La and the main winding Lp have the same-name ends at opposite positions, the second power switch MA is turned on during a first period of one pulse time before the first power switch MP is switched from the off state to the on state, a current flows into the auxiliary winding La, and a voltage across Vds of both ends of the first power switch MP rises from a potential at the time of the first power switch MP being turned off to a first potential through a coupling relationship between the main winding Lp and the auxiliary winding La of the transformer TS; during a second period of one pulse time before the first power switch MP is switched from the off state to the on state, the second power switch MA is turned off, and after the voltage across Vds across the first power switch MP is reduced from the first potential to the second potential lower than the first potential, the first power switch MP is switched from the off state to the on state, so that the switching loss of the first power switch MP is lower.
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, as shown in fig. 2c, the auxiliary winding La and the main winding Lp have the same-name terminals at the same position, and when the voltage of the detection signal SWA at the control terminal of the normally-on switch MJ is lower than the preset reference voltage VREF during the demagnetization of the transformer TS, the detection module outputs the demagnetization signal ZXC indicating the end of the demagnetization of the transformer TS.
In one embodiment, as shown in fig. 2c, the auxiliary winding La and the main winding Lp have the same-name ends at opposite positions, and the detection module outputs a demagnetizing signal ZXC indicating the end of demagnetization of the transformer TS when the voltage of the detection signal SWA at the control end of the normally-on switch MJ is higher than the preset reference voltage VREF during the demagnetization of the transformer TS.
In one embodiment, the working principle of the detection module of the present invention may be further understood with reference to fig. 2c and 3c, where the detection module includes a hysteresis comparator and a pull-down resistor Rsn, and a first input terminal of the hysteresis comparator is coupled to a preset reference voltage VREF, and in one embodiment, the preset reference voltage VREF is zero voltage; the second input end of the hysteresis comparator is coupled to the first end of the pull-down resistor Rsn and the detection signal SWA of the control end of the normally-on switch MJ, the second end of the pull-down resistor Rsn is coupled to the preset reference voltage VREF or zero voltage, after the demagnetization of the transformer TS is finished, the oscillation signal of the second end of the auxiliary winding La is coupled to the control end of the normally-on switch MJ through the parasitic cross capacitance Cdg between the first end and the control end of the normally-on switch MJ, so as to generate the detection signal SWA, and when the voltage of the detection signal SWA of the second input end of the hysteresis comparator is lower than the voltage VREF of the first input end (at this time, the first input end corresponds to the in-phase end of the hysteresis comparator, and the second input end corresponds to the inverting end of the hysteresis comparator), the output end of the hysteresis comparator outputs the demagnetization signal ZXC indicating the completion of the demagnetization of the transformer TS. In one embodiment, the demagnetization signal ZXC changes from low to high, indicating that the demagnetization of the transformer TS is finished.
In one embodiment, as shown in fig. 2c, the detection module includes a hysteresis comparator and a pull-down resistor Rsn, a first input terminal of the hysteresis comparator is coupled to a preset reference voltage VREF, in one embodiment, the preset reference voltage VREF is zero, a second input terminal of the hysteresis comparator is coupled to a first terminal of the pull-down resistor Rsn and a detection signal SWA of a control terminal of the normally-on switch MJ, a second terminal of the pull-down resistor Rsn is coupled to the preset reference voltage VREF or zero voltage, after the demagnetization of the transformer TS is finished, an oscillation signal of a second terminal of the auxiliary winding La is coupled to the control terminal of the normally-on switch MJ through a parasitic transcapacitive Cdg between the first terminal and the control terminal of the normally-on switch MJ, so as to generate the detection signal SWA, when the voltage of the detection signal SWA of the second input terminal of the hysteresis comparator is higher than the voltage VREF of the first input terminal (at this time, the second input terminal corresponds to the same terminal of the hysteresis comparator, and the first input terminal corresponds to the inverting terminal of the hysteresis comparator), and the output signal xc of the output terminal of the hysteresis comparator is finished. In one embodiment, the demagnetization signal ZXC changes from low to high, indicating that the demagnetization of the transformer TS is finished.
In one embodiment, as shown in fig. 2b, the normally-on switch MJ is a Junction Field Effect Transistor (JFET), and in one embodiment, when the control terminal of the JFET is pulled down to ground by the pull-down resistor Rsn, the highest voltage at the second terminal of the JFET is the pinch-off voltage of the JFET, which is equivalent to the normally-on switch MJ charging the supply capacitor CP with the pinch-off voltage of the JFET, and the supply capacitor CP provides the supply voltage VCC to the outside.
In one embodiment, as shown in fig. 2b, the normally-on switch MJ is a depletion-mode metal oxide semiconductor field effect transistor (depletion-mode MOSFET).
In one embodiment, as shown in FIG. 2b, normally-on switch MJ is a depletion gallium nitride transistor GaN (D-GaN).
In a second aspect, an embodiment of the present invention provides a power supply system. As shown in fig. 1a, the first power supply system 11 includes the first auxiliary circuit 110 according to the first aspect, the input end of the power supply system is coupled to the ac voltage VAC, and further includes an input capacitor CIN, an output capacitor CO of a parallel load, a control module and a power stage, where the first auxiliary circuit 110 provides a supply voltage VCC for the control module; the power stage at least comprises a main stage winding Lp of a transformer TS, a first power switch MP and a follow current module 121, wherein a first control signal GP output by the control module is coupled with a control end of the first power switch MP to control the on and off of the first power switch MP; the second control signal GA output by the control module is coupled with the control end of the second power switch MA and controls the on and off of the second power switch MA; the connection relation between the power stage and the input capacitor CIN and the output capacitor CO can be combined to form any one of a buck power supply system, a boost power supply system, a flyback power supply system and a boost power supply system.
In one embodiment, as shown in fig. 1a, the first power supply system 11 further includes a driving chip, and the driving chip includes at least an auxiliary module and a control module.
In one embodiment, the first power system 11 further includes a rectifier bridge, an input terminal of the rectifier bridge is coupled to the ac voltage VAC and the X capacitor CX, 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 Metal Oxide Semiconductor Field Effect Transistor (MOSFET), and the power stage including the MOSFET constitutes a synchronous rectification structure.
In one embodiment, as shown in fig. 1b, the main winding Lp and the auxiliary winding La of the transformer TS of the second power supply system 12 have identical terminals at the same position, and the input terminal of the second power supply system 12 is coupled to the ac voltage VAC, and includes an X capacitor CX, a rectifier bridge, an input capacitor CIN, an output capacitor CO coupled to a load in parallel, a first auxiliary circuit 110, a control module, and a second power stage 120, and the second power stage 120 includes the main winding Lp, the freewheel module 121, and the first power switch MP; a first terminal of the output capacitor CO is coupled to a first terminal of the input capacitor CIN and a second terminal of the freewheel module 121; the second terminal of the input capacitor CIN is coupled with the ground; the homonymous end of the main stage winding Lp is coupled with the second end of the output capacitor CO; the same-name end of the auxiliary winding La is also the first end of the auxiliary winding La, the non-same-name end of the auxiliary winding La is also the second end of the auxiliary winding La, the first end of the auxiliary winding La is coupled with the sampling voltage VIC of the first end of the holding capacitor CIC, and the second end of the auxiliary winding La is coupled with the first port P1 of the auxiliary module. 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 freewheel module 121; the control end of the first power switch MP is coupled with a first control signal GP output by the control module, the second end of the first power switch MP is grounded or grounded after passing through a current detection resistor, and the first control signal GP output by the control module controls the on and off of the first power switch MP.
In one embodiment, as shown in fig. 1b, 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, and 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 TS, the voltage drop on the auxiliary winding La is also kept at VIN-VO or approximately equal to VIN-VO when the number of turns of the main winding Lp and the auxiliary winding La is the same or approximately the same; during charging of the primary winding Lp, the voltage at the second terminal of the auxiliary winding La is VIC- (VIN-VO) =vic-vin+vo; during the turn-off period of the first power switch MP, the load voltage VO on the output capacitor CO discharges the main winding Lp, and at this time, the voltage drop on the main winding Lp is approximately-VO, and by the coupling relationship of the transformer TS, the voltage drop on the auxiliary winding La is also maintained at-VO or approximately-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 discharge of the main stage winding Lp, the voltage at the second end of the auxiliary winding La is VIC- (-VO) =vic+vo, so that the auxiliary module can take power from the second end of the auxiliary winding La to supply the supply voltage VCC to the control module, regardless of whether the transformer TS is charged or discharged. After the demagnetization of the main winding Lp is finished, the parasitic capacitance Coss of the first end of the main winding Lp and the first power switch MP generates LC resonance, the potential of the non-homonymous end of the main winding Lp is reduced from VIN, the potential of the non-homonymous end of the auxiliary winding La is synchronously reduced through the coupling relation of the transformer TS, through the coupling action of the parasitic cross capacitance Cdg between the first end and the control end of the normally-on switch tube MJ, as shown in fig. 2b, the oscillation signal of the non-homonymous end of the auxiliary winding La is coupled to the control end of the normally-on switch MJ to generate a detection signal SWA, and during the demagnetization of the main winding Lp, the detection signal SWA of the control end of the normally-on switch MJ is compared with a preset reference voltage VREF by the detection module, and when the voltage of the detection signal SWA of the control end of the normally-on switch MJ is lower than the preset reference voltage VREF by combining fig. 2c and fig. 3c, the detection module outputs a demagnetization signal ZXC representing the completion of the demagnetization of the transformer TS.
In one embodiment, in conjunction with the waveform diagram shown in fig. 3a, before the primary winding Lp of the transformer TS begins to charge, the second power switch MA is turned on for a part or all of a pulse time T13, so that the current flowing through the second power switch MA flows through the auxiliary winding La to form an auxiliary winding current Ia, and the auxiliary winding current Ia is coupled to the primary winding Lp through the coupling action of the transformer TS to generate a primary winding current Ip with an opposite direction, and the primary winding current Ip reduces the voltage across the voltage Vds across the first power switch MP connected in series with the primary winding Lp from a first potential to a second potential that is lower when the first power switch MP is turned off, and the first power switch MP is turned on again from the off state, so that the switching loss of the first power switch MP is lower.
In the waveform diagram shown in fig. 3a, the time point T1 corresponds to a time point when the second power switch MA is turned on in preference to the first power switch MP, and in one embodiment, the time point T1 is generated in response to the demagnetizing signal ZXC of the transformer TS; in one embodiment, the T1 time point is generated in response to one trough of the voltage across Vds of the first power switch MP (or the first trough or the nth trough), and after the demagnetization of the transformer TS is finished, LC resonance occurs between the main winding Lp and the parasitic capacitance Coss of the first end of the first power switch MP, and a plurality of troughs are generated on the voltage across Vds of the first power switch MP; in one embodiment, the T1 time point is generated in response to a pulse width modulated signal (PWM signal) of the power supply system.
In the waveform diagram shown in fig. 3a, the time point T3 corresponds to the on time point of the first power switch MP, the period between the time point T1 and the time point T3 is a pulse time T13 when the second power switch MA is turned on before the first power switch MP, the length of the pulse time T13 and the magnitude of the auxiliary winding current Ia flowing through the auxiliary winding La determine the amplitude of the voltage across Vds of the first power switch MP from the initial first potential to the lower second potential, and in one embodiment, the first power switch MP is turned on again after the second potential approaches zero potential by optimizing the width of the pulse time T13 and the magnitude of the auxiliary winding current Ia, so as to realize the switching of the first power switch MP in the zero voltage state or the state of lower switching loss.
In the waveform diagram shown in fig. 3a, the time point T3 is the off time point of the second power switch MA and is also the on time point of the first power switch MP, and in one embodiment, the off time point of the second power switch MA is a time point T2 between the time point T1 and the time point T3, which corresponds to that the second power switch MA is not turned on during the whole pulse time T13, but is turned on only during the first period T12 of the pulse time T13, and is turned off during the second period T23, which corresponds to that T23 is the dead time of the first power switch MP and the second power switch MA.
The second power supply system 12 belongs to a step-down power supply system, and when the second power supply system 12 is in normal operation, the ac voltage VAC generates the input voltage VIN on the input capacitor CIN after passing through the rectifier bridge, and the ac voltage VAC simultaneously generates the sampling voltage VIC on the holding capacitor CIC through the first sampling diode DC1 and the second sampling diode DC2, and in one embodiment, the capacitance value of the holding capacitor CIC is far smaller than the capacitance value of the input capacitor CIN, and since the holding capacitor CIC supplies energy to the auxiliary winding, the input capacitor CIN needs to supply energy to the load, and therefore the holding capacitor CIC is only 1/10 or smaller of the capacitance value of the input capacitor CIN (the capacitance value of the holding capacitor CIC is merely an exemplary illustration and not a limitation).
When the second power supply system 12 enters the power-down state, which corresponds to that the ac voltage VAC is disconnected from the X capacitor CX, the second power supply system 12 will still continue to operate, and the first auxiliary circuit 110 will continue to consume the energy on the holding capacitor CIC and the X capacitor CX, and since the capacitance value of the holding capacitor CIC is much smaller than the capacitance value of the input capacitor CIN, the sampling voltage VIC on the holding capacitor CIC will be reduced faster than the input voltage VIN on the input capacitor CIN, so the energy on the X capacitor CX will be quickly transferred to the holding capacitor CIC, and then transferred to the power supply capacitor CP through the second power switch MA to be consumed by the power supply voltage VCC, especially when the second power supply system 12 operates under light load or empty load conditions, the voltage on the input capacitor CIN will drop more slowly, and therefore the X capacitor CX can be quickly discharged by the first auxiliary circuit 110 when the power supply system is powered down.
In one embodiment, as shown in the seventh power supply system 17 of fig. 5, the seventh power supply system 17 differs from the second power supply system 12 in that the primary winding Lp and the auxiliary winding La of the transformer TS of the seventh power supply system 17 have opposite identical ends, which also results in a large difference in the operation modes of the seventh power supply system 17 and the second power supply system 12.
As shown in fig. 5, 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, and at this time, the voltage drop across the main winding Lp is approximately VIN-VO (neglecting the on-voltage drop of the first power switch MP), and by the coupling relationship of the transformer TS, the voltage drop across the auxiliary winding La is also kept to be- (VIN-VO) or approximately equal to- (VIN-VO) 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 at the second terminal of the auxiliary winding La is vic+ (VIN-VO) =vic+vin+vo; during the turn-off period of the first power switch MP, 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 the voltage drop on the auxiliary winding La is kept at VO or approximately equal to VO under the condition that the turns of the main winding Lp and the auxiliary winding La are the same or approximately the same through the coupling relationship of the transformer TS; during discharge of the main winding Lp, the voltage at the second end of the auxiliary winding La is VIC- (VO) =vic-VO, so that the auxiliary module can take power from the second end of the auxiliary winding La to supply the supply voltage VCC to the control module, regardless of whether the transformer TS is charged or discharged. After the demagnetization of the main winding Lp is finished, the parasitic capacitance Coss of the first end of the main winding Lp and the first power switch MP generates LC resonance, the potential of the non-homonymous end of the main winding Lp is reduced from VIN, the potential of the non-homonymous end of the auxiliary winding La is synchronously increased through the coupling relation of the transformer TS, through the coupling action of the parasitic cross capacitance Cdg between the first end and the control end of the normally-on switch tube MJ, as shown in fig. 2b, the oscillation signal of the non-homonymous end of the auxiliary winding La is coupled to the control end of the normally-on switch MJ to generate a detection signal SWA, and during the demagnetization of the main winding Lp, the detection module compares the detection signal SWA of the control end of the normally-on switch MJ with a preset reference voltage VREF, and when the voltage of the detection signal SWA of the control end of the normally-on switch MJ is higher than the preset reference voltage VREF, the detection module outputs a demagnetizing signal ZXC representing the end of the transformer TS.
In combination with the seventh power supply system shown in fig. 5 and the waveform diagram shown in fig. 3b, the auxiliary winding La of the transformer TS and the main winding Lp have opposite-position identical-name ends, before the control module controls the output first control signal GP to change from a low level to a high level to control the first power switch MP to change from an off state to an on state, the control module outputs the second control signal GA to generate a high level in the first period T12 of the pulse time T13, the second power switch MA in the first auxiliary circuit 110 is enabled to conduct for the first period T12 to charge the auxiliary winding La, current flows through the auxiliary winding La, the auxiliary winding current Ia flowing through the auxiliary winding La is coupled to the main winding Lp through the coupling relation of the transformer TS, the main winding current Ip with the same direction is generated, the voltage Vds across the first power switch MP rises to the first potential VIN (ignoring the conduction voltage drop on the module 121), in the schematic diagram shown in fig. 3b, the second control signal GA is high level in the first period T12 of the pulse time T13, the second power switch MA is enabled to conduct for the first period T12, the second power switch MA is enabled to generate a voltage across the auxiliary winding La with the same direction as the main winding Ip, and the first voltage current Ip is coupled to the main winding Ip with the first voltage winding Ip, and the main winding Ip is connected in series with the same direction; in the second period T23 of the pulse time T13, the second control signal GA is at a low level, the second power switch MA is turned off, and the voltage across Vds at both ends of the first power switch MP is rapidly reduced from the initial first potential VIN to a lower second potential (for example, zero potential or a potential close to zero) in the second period T23 through the coupling relationship between the main winding Lp and the auxiliary winding La of the transformer TS, so that the first control signal GP output by the control module becomes at a high level, and the first power switch MP is controlled to be switched from the off state to the on state.
In the waveform diagram shown in fig. 3b, the time point T1 corresponds to a time point when the second power switch MA is turned on prior to the first power switch MP, and in one embodiment, the time point T1 is generated in response to the demagnetizing signal ZXC in which the demagnetization of the transformer TS is completed; in one embodiment, the T1 time point is generated in response to a trough of the voltage across the first power switch MP Vds (either the first trough or the nth trough); in one embodiment, the T1 time point is generated in response to a pulse width modulated signal (PWM signal) of the seventh power supply system 17.
In the waveform diagram shown in fig. 3b, the time point T3 corresponds to the on time point of the first power switch MP, the first period T12 between the time point T1 and the time point T2 is the pulse time for the second power switch MA to be turned on, the length of the first period T12, the length of the second period T23, and the magnitude of the auxiliary winding current Ia flowing through the auxiliary winding La determine the amplitude of the voltage across Vds of the first power switch MP from the initial first potential VIN to the lower second potential, and in one embodiment, the three parameters are optimized to make the second potential approach to the zero potential, and then the first power switch MP is turned on again to realize that the first power switch MP is switched in the zero voltage state.
The principle of the first auxiliary circuit 110 of the seventh power supply system 17 for rapidly discharging the X capacitor when the power supply system is powered down is the same as that of the second power supply system 12, and the description will not be repeated.
In one embodiment, as shown in the third power supply system 13 in fig. 1c, an input terminal of the third power supply system 13 is coupled to an ac voltage VAC, and includes an X capacitor CX, a rectifier bridge, an input capacitor CIN, an output capacitor CO coupled to a load in parallel, a first auxiliary circuit 110, a control module, and a third power stage 130, where the third power stage 130 includes 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 first end of the main stage winding Lp; a second end of the input capacitor CIN is coupled to ground, and a second end of the output capacitor CO is coupled to a second end of the freewheel module 121; the first end of the auxiliary winding La is coupled to the sampling voltage VIC of the first end of the holding capacitor CIC, and the second end of the auxiliary winding La is coupled to the first port P1 of the auxiliary module. A second 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 freewheel module 121; the control end of the first power switch MP is coupled with a first control signal GP output by the control module, the second end of the first power switch MP is grounded or grounded after passing through a current detection resistor, and the first control signal GP output by the control module controls the on and off of the first power switch MP.
The difference between the third power supply system 13 and the second power supply system 12 is that the third power supply system 13 belongs to a step-up and step-down power supply system, and is mainly characterized in that the positions of the output capacitor and the load of the third power supply system 13 are different; the principle of the first auxiliary circuit 110 of the third power supply system 13 in realizing the rapid discharging of the X capacitor CX of the third power supply system 13, and the principle of the first auxiliary circuit 110 of the third power supply system 13 outputting the power supply voltage VCC to externally supply power, or the principle of the first auxiliary circuit 110 of the third power supply system 13 detecting the demagnetizing state of the transformer TS is completely similar to the second power supply system 12 and the seventh power supply system 17, and in particular, reference may be made to the analysis of the second power supply system 12 (the auxiliary winding La and the main winding Lp of the transformer TS have the same-name ends in the same positions), and the analysis of the seventh power supply system 17 (the auxiliary winding La and the main winding Lp of the transformer TS have the same-name ends in opposite positions), which will not be repeated in the description.
In one embodiment, as shown in fig. 1d, the input terminal of the fourth power system 14 is coupled to an ac voltage VAC, and includes an X capacitor CX, a rectifier bridge, an input capacitor CIN, an output capacitor CO coupled in parallel to a load, a first auxiliary circuit 110, a control module, and a fourth power stage 140, where the fourth power stage 140 includes a primary winding Lp, a secondary winding Ls, a freewheel module 121, and a first power switch MP; the first end of the auxiliary winding La is coupled with the first end of the holding capacitor CIC, the second end of the auxiliary winding La is coupled with the first port P1 of the auxiliary module, the homonymous end of the main stage winding Lp is coupled with the first end of the input capacitor CIN, the homonymous end of the main stage winding Lp is coupled with the first end of the first power switch MP, the second end of the first power switch MP is grounded or grounded after passing through a current detection resistor, the homonymous end of the secondary winding Ls is coupled with the first end of the continuous flow module 121, the second end of the continuous flow module 121 is coupled with the first end of the output capacitor CO, and the second end of the output capacitor CO is coupled with the homonymous end of the secondary winding Ls; or the non-homonymous end of the secondary winding Ls is coupled with the first end of the output capacitor CO, the second end of the output capacitor CO is coupled with the first end of the follow current module 121, and the second end of the follow current module 121 is coupled with the homonymous end of the secondary winding Ls; the first control signal GP output by the control module controls the on and off of the first power switch MP, and the second control signal GA output by the control module controls the on and off of the second power switch MA.
The fourth power supply system 14 differs from the second power supply system 12 in that the fourth power supply system 14 belongs to a flyback power supply system; the principle of the first auxiliary circuit 110 of the fourth power supply system 14 in realizing the rapid discharging of the X capacitor CX of the fourth power supply system 14, and the principle of the first auxiliary circuit 110 of the fourth power supply system 14 outputting the power supply voltage VCC to externally supply power, or the principle of the first auxiliary circuit 110 of the fourth power supply system 14 detecting the demagnetizing state of the transformer TS is completely similar to that of the second power supply system 12 and the seventh power supply system 17, and in particular, reference may be made to the analysis of the second power supply system 12 (the auxiliary winding La and the main winding Lp of the transformer TS have the same-name ends at the same positions), and the analysis of the seventh power supply system 17 (the auxiliary winding La and the main winding Lp of the transformer TS have the same-name ends at opposite positions), which will not be repeated in the description.
In one embodiment, as shown in fig. 1e, the fifth power system 15 has an input terminal of the fifth power system 15 coupled to an ac voltage VAC, including an X capacitor CX, a rectifier bridge, an input capacitor CIN, an output capacitor CO coupled in parallel to a load, a first auxiliary circuit 110, a control module, and a fifth power stage 150, where the fifth power stage 150 includes a main stage winding Lp, a freewheel module 121, and a first power switch MP; a first end of the output capacitor CO is coupled to the second end of the freewheel module 121, a second end of the output capacitor CO is coupled to ground, and a first end of the input capacitor CIN is coupled to a first end of the main stage winding Lp; the second terminal of the input capacitor CIN is coupled with the ground; the first end of the auxiliary winding La is coupled to the sampling voltage VIC of the first end of the holding capacitor CIC, and the second end of the auxiliary winding La is coupled to the first port P1 of the auxiliary module. A second 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 freewheel module 121; the control end of the first power switch MP is coupled with a first control signal GP output by the control module, the second end of the first power switch MP is grounded, or is grounded after passing through a current detection resistor, the first control signal GP output by the control module controls the on and off of the first power switch MP, and the second control signal GA output by the control module controls the on and off of the second power switch MA.
The fifth power supply system 15 differs from the second power supply system 12 in that the fifth power supply system 15 belongs to a booster power supply system; the principle of the first auxiliary circuit 110 of the fifth power supply system 15 in realizing the rapid discharging of the X capacitor CX of the fifth power supply system 15, and the principle of the first auxiliary circuit 110 of the fifth power supply system 15 outputting the power supply voltage VCC to externally supply power, or the principle of the first auxiliary circuit 110 of the fifth power supply system 15 detecting the demagnetizing state of the transformer TS, are completely similar to those of the second power supply system 12 and the seventh power supply system 17, and in particular, reference may be made to the analysis of the second power supply system 12 (the auxiliary winding La and the main winding Lp of the transformer TS have the same-name ends at the same positions), and the analysis of the seventh power supply system 17 (the auxiliary winding La and the main winding Lp of the transformer TS have the same-name ends at opposite positions), which will not be repeated in the description.
In one embodiment, as shown in the sixth power system 16 of fig. 4, both the sixth power system 16 and the fourth power system 14 belong to a flyback power system; the difference between the sixth power supply system 16 and the fourth power supply system 14 is that the first end of the auxiliary winding La in the second auxiliary circuit 111 of the sixth power supply system 16 is not directly coupled to the sampling voltage VIC on the holding capacitor CIC, and the first end of the auxiliary winding La in the second auxiliary circuit 111 is coupled to the sampling voltage VIC on the holding capacitor CIC after passing through the absorption capacitor Clp. As can be seen from fig. 4, the input terminal of the sixth power supply system 16 is coupled to an ac voltage VAC, and includes an X capacitor CX, a rectifier bridge, an input capacitor CIN, an output capacitor CO coupled in parallel to a load, a second auxiliary circuit 111, a control module, a fourth power stage 140, and an absorption circuit 141, wherein the fourth power stage 140 includes a primary winding Lp, a secondary winding Ls, a freewheel module 121, and a first power switch MP; the second end of the absorption capacitor Clp is coupled to the first end of the holding capacitor CIC, the first end of the absorption capacitor Clp is coupled to the cathode of the absorption diode Dlp and the first end of the auxiliary winding La, the second end of the auxiliary winding La is coupled to the first port P1 of the auxiliary module, the homonymous end of the main stage winding Lp is coupled to the first end of the input capacitor CIN, the homonymous end of the main stage winding Lp is coupled to the first end of the first power switch MP and the anode of the absorption diode Dlp, the second end of the first power switch MP is grounded or grounded after passing through a current detection resistor, the homonymous end of the secondary winding Ls is coupled to the first end of the continuous current module 121, the second end of the continuous current module 121 is coupled to the first end of the output capacitor CO, and the second end of the output capacitor CO is coupled to the homonymous end of the secondary winding Ls; or the non-homonymous end of the secondary winding Ls is coupled with the first end of the output capacitor CO, the second end of the output capacitor CO is coupled with the first end of the follow current module 121, and the second end of the follow current module 121 is coupled with the homonymous end of the secondary winding Ls; the first control signal GP output by the control module controls the on and off of the first power switch MP, and the second control signal GA output by the control module controls the on and off of the second power switch MA.
When the first power switch MP is turned on, the input voltage VIN charges the main winding Lp, 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 by the coupling relationship of the transformer TS, the voltage drop on the auxiliary winding La is also kept at VIN or approximately VIN under the condition that the main winding Lp and the auxiliary winding La have the same-name terminals at the same positions and the winding turns are the same or approximately the same; during charging of the primary winding Lp, the voltage at the second end of the auxiliary winding La is (vic+ Nps VO) -VIN, (Nps is the turns ratio of the primary winding Lp and the secondary winding Ls); when the first power switch MP Is turned off, the load voltage VO on the output capacitor CO discharges the secondary winding Ls, generating a secondary winding current Is to charge the output capacitor CO, 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), and during the secondary winding Ls discharge, the voltage at the second end of the auxiliary winding La Is (vic+ Nps ×vo) - (-Nps ×vo) =vic+2mps×vo; the auxiliary module can thus take power from the second end of the auxiliary winding La, whether during charging or discharging of the transformer TS, providing the control module with the supply voltage VCC. 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, the potential at the non-homonymous end of the main winding Lp starts to decrease from vic+ Nps, the potential at the non-homonymous end of the auxiliary winding La also decreases synchronously through the coupling relationship of the transformer TS, and through the coupling effect of the parasitic transcapacitive Cdg between the first end and the control end of the normally-on switch MJ, as shown in fig. 2b, the oscillation signal at the non-homonymous end of the auxiliary winding La is coupled to the control end of the normally-on switch MJ to generate the detection signal SWA, and during the demagnetization of the transformer TS, the detection module compares the detection signal SWA at the control end of the normally-on switch MJ with the preset reference voltage VREF, and when the voltage of the detection signal SWA at the control end of the normally-on switch MJ is lower than the preset reference voltage VREF, in combination with fig. 2c and fig. 3c, the detection module outputs the demagnetized signal ZXC representing the completion of the demagnetization of the transformer TS.
In normal operation of the sixth power supply system 16, the ac voltage VAC is passed through the rectifier bridge to generate the input voltage VIN across the input capacitor CIN, and the ac voltage VAC is passed through both the first sampling diode DC1 and the second sampling diode DC2 to generate the sampling voltage VIC across the holding capacitor CIC, which in one embodiment has a substantially smaller capacitance than the input capacitor CIN, because the holding capacitor CIC is the auxiliary winding to which the input capacitor CIN is required to be supplied with energy, the holding capacitor CIC is only 1/10 of the input capacitor CIN or less (the capacitance of the holding capacitor CIC is merely an exemplary illustration and not a limitation).
When the sixth power supply system 16 enters the power-down state, which corresponds to that the ac voltage VAC is disconnected from the X-capacitor CX, the sixth power supply system 16 will still continue to operate, and the second auxiliary circuit 111 will continue to consume the energy on the holding capacitor CIC and the X-capacitor CX, and since the capacitance value of the holding capacitor CIC is much smaller than the capacitance value of the input capacitor CIN, the sampling voltage VIC on the holding capacitor CIC will decrease faster than the input voltage VIN on the input capacitor CIN, and therefore the energy on the X-capacitor CX will be quickly transferred to the holding capacitor CIC to be consumed, and especially when the sixth power supply system 16 is operated under light load or under empty load, the voltage on the input capacitor CIN will drop more slowly, and therefore, the X-capacitor CX can be quickly discharged by the second auxiliary circuit 111 when the power supply system is powered down.
When the auxiliary winding La and the main winding Lp of the transformer TS in the sixth power supply system 16 have the same-name ends at different positions, the description of the operation principle thereof will not be repeated.
In the above embodiments, in order to conveniently, more clearly and simply describe the working principle of the present application, the description only exemplifies the case that the number of turns of the main winding Lp and the auxiliary winding La of the transformer TS is the same, and in the practical implementation process, the number of turns of the main winding Lp and the auxiliary winding La of the transformer TS may be kept different, but the working principle of the present application is not affected.
As can be seen from the above embodiments, the connection relation between the first power stage 100 and the input capacitor CIN and the output capacitor CO can be combined to form any one of a Buck power supply system (Buck), a Boost power supply system (Boost), a Flyback power supply system (Flyback) and a Buck-Boost power supply system (Buck Boost).
In a third aspect, the present application also provides a power supply apparatus comprising any one of the power supply systems described in the second aspect.
From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:
according to the auxiliary circuit, the state of the second power switch is controlled, so that the X capacitor of the power supply system can be rapidly discharged when the power supply system is powered down. Compared with the prior art, the application improves the efficiency 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 (11)

1. An auxiliary circuit for use in a power supply system having a transformer and an X-capacitor, the transformer having at least an auxiliary winding and a primary winding, the auxiliary circuit comprising:
the sampling module is coupled with the X capacitor, and is configured to sample the voltage on the X capacitor and output the sampled voltage;
an auxiliary winding having two ends, wherein a first end is coupled to the sampling voltage or coupled to the sampling voltage after passing through a capacitor;
an auxiliary module coupled to a second end of the auxiliary winding, including at least a second power switch;
And by controlling the state of the second power switch, the auxiliary circuit enables the X capacitor of the power supply system to be rapidly discharged when the power supply system is powered down.
2. The auxiliary circuit according to claim 1, wherein the auxiliary circuit is further capable of supplying an electric voltage to the outside, or detecting a demagnetizing state of the transformer and outputting a demagnetizing signal indicating the end of demagnetization of the transformer.
3. The auxiliary circuit of claim 1, wherein the sampling module comprises a first sampling diode, a second sampling diode, and a holding capacitor, wherein an anode of the first sampling diode is coupled to a first end of the X-capacitor, an anode of the second sampling diode is coupled to a second end of the X-capacitor, a cathode of the first sampling diode and a cathode of the second sampling diode are coupled to the holding capacitor, and the sampling voltage is generated on the holding capacitor.
4. The auxiliary circuit of claim 1 wherein the auxiliary module has at least two ports, a first port coupled to the second end of the auxiliary winding and a second port coupled to a second control signal that controls the turning on and off of the second power switch.
5. The auxiliary circuit according to claim 4, wherein the auxiliary module comprises a second power switch and a power supply capacitor, a first end of the second power switch is coupled to a first port of the auxiliary module, a control end of the second power switch is coupled to a second port of the auxiliary module, a second end of the second power switch is coupled to the power supply capacitor and outputs a power supply voltage to supply power to the outside, and when the power supply system is powered down, the second power switch transfers the energy on the X capacitor to the power supply capacitor to generate the power supply voltage to supply power to the outside, and meanwhile, the X capacitor is rapidly discharged; or (b)
The auxiliary module comprises a second power switch, a normally-on switch, a power supply capacitor and a detection module, wherein a first end of the normally-on switch is coupled with a first port of the auxiliary module, a second end of the normally-on switch is coupled with a first end of the second power switch, a control end of the normally-on switch is coupled with the detection module, and the detection module outputs a demagnetizing signal indicating the demagnetization of the transformer through detecting the control end of the normally-on switch; the control end of the second power switch is coupled with a second port of the auxiliary module, the second end of the second power switch is coupled with the power supply capacitor and outputs power supply voltage to supply power to the outside, and when the power supply system is powered down, the second power switch and the normally-on switch transfer the energy on the X capacitor to the power supply capacitor to generate the power supply voltage to supply power to the outside, and meanwhile the X capacitor is rapidly discharged.
6. An auxiliary circuit according to claim 1, wherein the second power switch of the auxiliary circuit is turned on for a part or all of a pulse time before the primary winding of the transformer starts to charge, causing current flowing through the second power switch to flow through the auxiliary winding.
7. The auxiliary circuit according to claim 6, wherein the primary winding of the transformer is connected in series with the first power switch, the auxiliary winding and the primary winding have identical terminals at the same positions, the second power switch is turned on for a part or all of a pulse time before the first power switch is switched from an off state to an on state, a current flows into the auxiliary winding, and a voltage across the first power switch is reduced from a first potential when the first power switch is turned off to a second potential lower than the first potential when the first power switch is turned off through a coupling relation between the primary winding and the auxiliary winding of the transformer, and the first power switch is switched from the off state to the on state again, so that the switching loss of the first power switch is lower; or (b)
The main-stage winding and the first power switch of the transformer are connected in series, the auxiliary winding and the main-stage winding have the same-name ends at opposite positions, the second power switch is conducted in a first period of one pulse time before the first power switch is switched from an off state to an on state, current flows into the auxiliary winding, and the voltage across the two ends of the first power switch rises from the potential when the first power switch is turned off to a first potential through the coupling relation between the main-stage winding and the auxiliary winding of the transformer; in a second period of one pulse time before the first power switch is switched from the off state to the on state, the second power switch is turned off, and after the voltage across the two ends of the first power switch is reduced from the first potential to a second potential which is lower through the coupling relation between the main winding and the auxiliary winding of the transformer, the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower.
8. A power supply system comprising at least the auxiliary circuit of any one of claims 1 to 7, wherein the power supply system further comprises an input capacitance, an output capacitance, a control module and a power stage; the power stage at least comprises a main stage winding of the transformer, a first power switch and a follow current module, wherein a first control signal output by the control module is coupled with a control end of the first power switch to control the on and off of the first power switch; the second control signal output by the control module is coupled with the control end of the second power switch and controls the on and off of the second power switch; the connection relation between the power level and the input capacitor and the output capacitor can be combined to form any one of a buck power supply system, a boost power supply system, a flyback power supply system and a boost power supply system.
9. The power system of claim 8, wherein the control module controls the second power switch in the auxiliary circuit to conduct for a portion or all of a pulse time before the first power switch is switched from the off state to the on state, such that current flowing through the second power switch flows through the auxiliary winding.
10. The power supply system according to claim 9, wherein the auxiliary winding and the main winding of the transformer of the power supply system have the same-name ends at the same position, and the second power switch is turned on for a part or all of a pulse time before the first power switch is switched from the off state to the on state, and current flows into the auxiliary winding, and after the voltage across the first power switch is reduced from a first potential when the first power switch is turned off to a second potential lower than the first potential through a coupling relationship between the main winding and the auxiliary winding of the transformer, the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower; or (b)
The auxiliary winding and the main winding of the transformer of the power supply system have the same-name ends at opposite positions, the second power switch is conducted in a first period of one pulse time before the first power switch is switched from an off state to an on state, current flows into the auxiliary winding, and through a coupling relation between the main winding and the auxiliary winding of the transformer, the voltage across the two ends of the first power switch rises from the potential when the first power switch is turned off to a first potential; in a second period of one pulse time before the first power switch is switched from the off state to the on state, the second power switch is turned off, and after the voltage across the two ends of the first power switch is reduced from the first potential to a second potential which is lower through the coupling relation between the main winding and the auxiliary winding of the transformer, the first power switch is switched from the off state to the on state, so that the switching loss of the first power switch is lower.
11. A power supply device characterized by comprising the power supply system according to any one of claims 8 to 10.
CN202311339352.5A 2023-10-17 2023-10-17 Auxiliary circuit, power supply system and power supply device Pending CN117097139A (en)

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