CN111313710B - Self-current-sharing high-frequency star-shaped LLC resonance combined conversion device and control method thereof - Google Patents
Self-current-sharing high-frequency star-shaped LLC resonance combined conversion device and control method thereof Download PDFInfo
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- CN111313710B CN111313710B CN202010273622.7A CN202010273622A CN111313710B CN 111313710 B CN111313710 B CN 111313710B CN 202010273622 A CN202010273622 A CN 202010273622A CN 111313710 B CN111313710 B CN 111313710B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
-
- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
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Abstract
The invention discloses a self-current-sharing high-frequency star-shaped LLC resonance combination conversion device and a control method thereof, wherein the device comprises a primary side input circuit and a secondary side output circuit, and the primary side input circuit and the secondary side output circuit are connected through a transformer; the primary side input circuit comprises an LLC resonant circuit which is connected in a high-frequency star mode and is more than or equal to two paths, and the LLC resonant circuit which is connected in a high-frequency star mode comprises an LLC resonant circuit which is more than or equal to two paths; the secondary side output circuit comprises an LLC resonant output circuit which is connected in a high-frequency star mode and is more than or equal to two paths, and the LLC resonant output circuit which is connected in a high-frequency star mode comprises an LLC resonant output circuit which is more than or equal to two paths. The invention realizes the current sharing function of instantaneous current and average current in the resonant conversion of the two high-frequency star-shaped LLC, and achieves the effect of self current sharing.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to a self-current-sharing high-frequency star-shaped LLC resonance combined conversion device and a control method thereof.
Background
With the development of computer and communication technologies, a low-voltage high-current switching power supply is also an important research subject, and in the current industry, in the power supply outputting low-voltage high current, for example, 20VDC/1000A, the adopted power supply DC/DC conversion technology is mostly a phase-shifting full-bridge technology, and the technology has relatively low conversion efficiency, large volume and low power density. If single full-bridge LLC resonance DC/DC conversion is adopted, the switching-off current is greatly reduced by increasing exciting inductance when the full-load range Zero Voltage Switch (ZVS) and the switching frequency of MOSFET in an LLC (inductance-capacitance) full-bridge resonance circuit are smaller than or equal to the resonance frequency, and a secondary rectifying diode has almost no reverse recovery, so that the characteristics can improve the conversion efficiency, but the defects of overlarge current pulsation at an output end, large space and volume and high cost exist; if the high-frequency star LLC resonance is adopted, the output pulsation can be effectively reduced, the space and the cost are reduced, the reliability is improved, and the engineering implementation is more feasible, but when the two high-frequency star LLC resonances are combined, the original secondary side is typically connected in parallel, and the original side is connected in series, and the two topologies are connected in parallel, so that some effective control strategies are needed to ensure the current sharing of the two high-frequency star LLC resonance transformations; for the topology of primary side series-secondary side parallel connection, the primary side input voltage of two star-shaped LLC resonances is usually ensured to be equal, for example, a midpoint balance method or other effective control strategies are adopted, so that the topology is equivalent to the topology of direct input-output parallel connection. For the topology that two high-frequency star-shaped LLC resonance inputs and outputs are directly connected in parallel, when the resonance parameter deviates from the central value greatly, the problem that the difference between the two paths of transformed output currents is obvious still occurs. The DC/DC conversion technology in the existing switching power supply adopts a phase-shifting full-bridge technology, the hysteresis bridge arm is related to the ZVS and the load current, and soft switching cannot be realized in light load; the output rectifier diode has reverse recovery loss, so that conversion efficiency can be influenced, and the output needs larger-volume inductance L filtering, so that the cost is increased, and the volume of the converter is influenced. In the structure of the two high-frequency star-shaped LLC resonant DC/DC conversion circuits, the two high-frequency resonant conversion power switching tubes, the diode resonant inductor and the main transformer are greatly different in loss, so that electric stress or thermal stress is easy to exceed the design requirement, or potential reliability hazards are caused.
Therefore, how to provide a scheme of self-current-sharing high-frequency star-shaped LLC resonance combination transformation is a technical problem to be solved in the field.
Disclosure of Invention
The invention provides a self-current-sharing high-frequency star-shaped LLC resonance combined conversion device and a control method thereof, which are used for solving the technical problems of low DC/DC conversion efficiency, poor reliability, high cost and large converter volume in the power supply in the prior art.
The invention provides a self-current-sharing high-frequency star-shaped LLC resonance combined conversion device, which comprises: the primary side input circuit and the secondary side output circuit are connected through a transformer;
The primary side input circuit comprises an LLC resonant circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonant circuit which is connected in the high-frequency star mode comprises an LLC resonant circuit which is more than or equal to two paths, and the LLC resonant circuit comprises: two resonant switches, a coupling inductor, a resonant capacitor and primary sides of two series transformers; after the coupling inductor, the resonance capacitor and the primary winding initial end of the series transformer are connected in series, one end of the coupling inductor is connected between the two resonance switches in series; in the LLC resonant circuit connected in a high-frequency star mode, the primary winding termination end of the series transformer in the LLC resonant circuit is connected to form a star connection point;
The secondary side output circuit comprises an LLC resonance output circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonance output circuit which is connected in a high-frequency star mode comprises an LLC resonance output circuit which is more than or equal to two paths, the LLC resonance output circuit comprises two transformer secondary side output circuits of the series transformer, and the transformer secondary side output circuit comprises: the secondary side of the single transformer is connected with the output control and then connected to the power supply rectification output end.
Optionally, primary sides of the series transformers in the primary side input circuit are connected in parallel, and secondary sides of the single transformers in the secondary side output circuit are connected in parallel.
Optionally, two resonant switches of the LLC resonant circuit form a bridge arm of the LLC resonant circuit connected in a high-frequency star, and in the primary input circuit, drive signals of upper and lower tubes of each bridge arm are 180 degrees different.
Optionally, two resonant switches of the LLC resonant circuit form a bridge arm of the LLC resonant circuit connected in a high-frequency star, and in the primary input circuit, drive signals of different bridge arms are different in phase by 120 degrees.
Optionally, the secondary side of each transformer is a full-bridge rectifying output circuit.
Optionally, the output control is an output diode or a MOS transistor.
Optionally, the primary side input circuit includes 6 LLC resonant circuits, and the secondary side output circuit includes 6 LLC resonant output circuits.
Optionally, 6 bridge arms of the 6-way LLC resonant circuit in the primary side input circuit are divided into two star-shaped connection bridge arm groups, and the switch driving signals of 3 bridge arms in the star-shaped connection bridge arm groups are identical in phase relative to the driving signals of the other 3 bridge arms.
Optionally, in the star connection bridge arm group, the secondary sides of the series transformers corresponding to the same-phase bridge arms of each pair of switch driving signals are in cross series.
On the other hand, the invention also provides a control method of the self-current-sharing high-frequency star-shaped LLC resonance combined conversion device, which comprises the following steps:
Input voltage is carried out at the input of primary side input circuit, primary side input circuit includes the LLC resonant circuit of the high frequency star connection of two way or more, the LLC resonant circuit of high frequency star connection includes the LLC resonant circuit of two way or more, the LLC resonant circuit includes: two resonant switches, a coupling inductor, a resonant capacitor and primary sides of two series transformers; after the coupling inductor, the resonance capacitor and the primary winding initial end of the series transformer are connected in series, one end of the coupling inductor is connected between the two resonance switches in series; in the LLC resonant circuit connected in a high-frequency star mode, the primary winding termination end of the series transformer in the LLC resonant circuit is connected to form a star connection point;
The input voltage passes through the primary side of the series transformer in the LLC resonant circuit connected in a high-frequency star mode, and enters a secondary side output circuit after being transformed by the transformer; the secondary side output circuit comprises an LLC resonance output circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonance output circuit which is connected in a high-frequency star mode comprises an LLC resonance output circuit which is more than or equal to two paths, the LLC resonance output circuit comprises two transformer secondary side output circuits of the series transformer, and the transformer secondary side output circuit comprises: the secondary side of the single transformer is connected with the output control and then connected to the power supply rectification output end;
and outputting the current which is equalized through the power supply rectification output end in the secondary side output circuit.
The self-current-sharing high-frequency star-shaped LLC resonant combined conversion device and the control method thereof adopt the LLC resonant converter to realize the ZVS and the off current controllability of the full load range of the switching tube, achieve the approximate zero current off (ZCS), adopt diode rectification or synchronous rectification on the secondary side, and can reduce the loss caused by the diode due to no reverse recovery, thereby greatly improving the conversion efficiency.
In the mode that secondary sides of two transformers connected in series in the same-phase bridge arm in two high-frequency star-shaped LLC resonant conversions are connected in series in a crossing way, when the resonance inductance in the first star-shaped resonant conversion deviates from a central value by +5%, and the resonance capacitance deviates from the central value by +5%, the resonance inductance in the second star-shaped resonant conversion deviates from the central value by-5%, and when the resonance capacitance deviates from the central value by-5%, the output current instantaneous waveform of the second star-shaped LLC resonant conversion is the same as that of the first star-shaped LLC resonant conversion, so that the current equalizing function of instantaneous current and average current in the two high-frequency star-shaped LLC resonant conversions is well realized, and the self-equalizing effect is achieved.
The two star-shaped LLC resonant transformation realizes good current sharing, reduces total loss and voltage and current stress, thereby reducing the power capacity and the current capacity of the selected power tube and reducing the cost; the thermal stress of the switching tube, the main transformer and the resonant inductor is reduced, and the reliability is improved. .
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a phase-shifting full-bridge conversion circuit in the prior art;
FIG. 2 is a schematic diagram of a configuration of two high frequency star LLC resonant conversion parallel circuits;
FIG. 3 is a diagram showing the simulation effect of the output current after the resonance parameters of two high-frequency star LLC resonant transformation parallel circuits deviate from the central value;
FIG. 4 is a schematic circuit diagram of a self-current-sharing high-frequency star LLC resonant combined conversion device in an embodiment of the invention;
FIG. 5 is a graph showing the simulation effect of the output current of the high-frequency star LLC resonant transformation parallel circuit with good self-current sharing in the embodiment of the invention when the resonant capacitance parameter is deviated from the central value as well;
Fig. 6 is a schematic diagram of flow steps of a control method of a self-current-sharing high-frequency star-shaped LLC resonant combination converter according to an embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. 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.
As shown in fig. 1, the DC/DC (direct current/direct current) conversion in the conventional switching power supply generally adopts a phase-shifting full-bridge technology, which is a mature soft switching technology, and the phase-shifting control mode is that the switches S1 and S2 are turned on in turn, and each switch is turned on by 180 degrees in electrical angle, so are the switches S3 and S4. But S1 (or S2) and S4 (or S3) are not simultaneously turned on, and the two are turned on by a certain electrical angle, wherein S1 and S2 are turned off before S4 and S3 respectively, so the bridge arm formed by S1 and S2 is called a leading bridge arm, and the bridge arm formed by S3 and S4 is called a lagging bridge arm. ZVS of the switch is achieved in a phase-shifting manner in combination with resonance of the inductor and the switch junction capacitance (or shunt capacitance). However, as the hysteresis bridge arm realizes ZVS and the load current is related to the magnitude, soft switching cannot be realized in light load; in addition, the output rectifier diode has reverse recovery loss, so that the conversion efficiency can be influenced, and the output needs larger-volume inductance L filtering, so that the cost is increased, and the volume of the converter is influenced.
As shown in fig. 2 and 3, fig. 2 is a structure of two high-frequency star-shaped LLC resonant DC/DC conversion circuits; FIG. 3 is a graph showing simulated effects of output current after two high frequency star LLC resonant transformation parallel circuits have resonant parameters that deviate from a center value, when a resonant inductance in a first star resonant transformation deviates from the center value by +5% and a resonant capacitance deviates from the center value by +5%, a resonant inductance in a second star resonant transformation deviates from the center value by-5%, and when the resonant capacitance deviates from the center value by-5%, the second star resonant transformation output current is about 38% greater than the first resonant transformation output current, the first star LLC resonant output current is about 420A, and the second star LLC resonant output current is about 580A; the two are very different, which leads to the increase of the difference of the two high-frequency resonant conversion power switch tubes, the diode resonant inductor and the main transformer in loss, and further leads to the fact that the electric stress or the thermal stress exceeds the design requirement easily, and has potential reliability hazards.
Therefore, in this embodiment, a self-current-sharing high-frequency star LLC resonant combined transformation device is provided, which includes: the primary side input circuit and the secondary side output circuit are connected through a transformer; the primary side input circuit comprises an LLC resonant circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonant circuit which is connected in the high-frequency star mode comprises an LLC resonant circuit which is more than or equal to two paths, and the LLC resonant circuit comprises: two resonant switches, a coupling inductor, a resonant capacitor and primary sides of two series transformers; after the coupling inductor, the resonance capacitor and the primary winding initial end of the series transformer are connected in series, one end of the coupling inductor is connected in series between the two resonance switches; in the LLC resonant circuit with high-frequency star connection, the primary winding termination ends of series transformers in the LLC resonant circuit are connected to form a star connection point.
The secondary side output circuit comprises an LLC resonance output circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonance output circuit which is connected in a high-frequency star mode comprises an LLC resonance output circuit which is more than or equal to two paths, the LLC resonance output circuit comprises two transformer secondary side output circuits of a series transformer, and the transformer secondary side output circuit comprises: the secondary side of the single transformer is connected with the output control and then connected to the power supply rectification output end.
Alternatively, primary sides of series transformers in the primary side input circuit are connected in parallel, and secondary sides of individual transformers in the secondary side output circuit are connected in parallel.
Optionally, two resonant switches of the LLC resonant circuit form a bridge arm of the LLC resonant circuit connected in a high-frequency star, and in the primary input circuit, drive signals of upper and lower tubes of each bridge arm are 180 degrees different, and drive signals of different bridge arms are 120 degrees different in phase.
Optionally, the secondary side of each transformer is a full-bridge rectifying output circuit. The output control can be an output diode (shown in fig. 4) or a MOS transistor.
The circuit structure diagram is shown in fig. 4, wherein the whole power circuit comprises 6 primary side inputs and 6 secondary side outputs from top to bottom, the power circuit is suitable for being used for inputting 400VDC and outputting 20VDC/1000A, the whole power circuit comprises 6 LLC resonant primary side input circuits and 6 LLC resonant circuit secondary side output circuits from top to bottom, the primary side is an LLC resonant circuit in a high-frequency star connection mode, and one primary side input circuit corresponds to one coupled secondary side output circuit; each primary side input circuit comprises two switches, an inductor, a resonant capacitor and two transformers which are connected in series; each secondary side output circuit comprises two transformer secondary sides connected in series, four output diodes or four MOS tubes. Fig. 5 is a graph showing the simulation effect of the output current of the high-frequency star LLC resonant transformation parallel circuit with good self-current sharing in the embodiment when the resonant capacitance parameter is also deviated from the center value.
Specifically, the input voltage Vi is respectively connected to 6 primary input circuits, the first primary input circuit includes a first switch S1 and a second switch S2, where the second switch S2 is grounded, the first switch S1 and the second switch S2 are connected to one end of a first resonant inductor L1, the other end of the first resonant inductor L1 is connected to a first resonant capacitor C1, the other end of the first resonant capacitor C1 is connected to one end of a primary winding of the first transformer T1, the other end of the primary winding of the first transformer T1 is connected to one end of a primary winding of the second transformer T2, and the other end of the primary winding of the second transformer T2 is connected to one end of a primary winding of the fourth transformer T4 and one end of a primary winding of the sixth transformer T6 to form a first star connection point; the secondary side of the first transformer T1 is connected with the secondary side of the eighth transformer T8 in series, and the secondary side needs to keep the corresponding relation with the same name end of the primary side; the two ends after being connected in series are connected with a first diode D1, a second diode D2, a fifteenth diode D15 and a sixteenth diode D16 to form a full-bridge rectifying circuit.
The second primary input circuit comprises a third switch S3 and a fourth switch S4, wherein the fourth switch S4 is grounded, the third switch S3 and the fourth switch S4 are connected with one end of a second resonant inductor L2, the other end of the second resonant inductor L2 is connected with a second resonant capacitor C2, the other end of the second resonant capacitor C2 is connected with a primary winding of a third transformer T3, the other end of the primary winding of the third transformer T3 is connected with one end of the primary winding of the fourth transformer T4, and the other end of the primary winding of the fourth transformer T4 is connected with one end of the primary winding of the second transformer T2 and one end of the primary winding of a sixth transformer T6 to form a first star-shaped connection point; the second secondary side output circuit is formed by connecting a secondary side of the third transformer T3 with a secondary side of the tenth transformer T10 in series, the secondary side needs to keep a corresponding relation with the same-name end of the primary side, and the two ends after being connected in series are connected with a fifth diode D5, a sixth diode D6, a nineteenth diode D19 and a twentieth diode D20 to form a full-bridge rectifying circuit.
The third primary input circuit comprises a fifth switch S5 and a sixth switch S6, wherein the sixth switch S6 is grounded, the fifth switch S5 and the sixth switch S6 are connected with a first homonymous end of a third resonant inductor L3, the other end of the third resonant inductor L3 is connected with a third resonant capacitor C3, the other end of the third resonant capacitor C3 is connected with a primary winding of a fifth transformer T5, the other end of the primary winding of the fifth transformer T5 is connected with one end of the primary winding of a sixth transformer T6, and the other end of the primary winding of the sixth transformer T6 is connected with one end of the primary winding of a second transformer T2 and one end of the primary winding of a fourth transformer T4 to form a first star connection point; the third secondary side output circuit is formed by connecting a secondary side of a fifth transformer T5 with a secondary side of a twelfth transformer T12 in series, the secondary side needs to keep a corresponding relation with a same name end of the primary side, and a ninth diode D9, a tenth diode D10, a twenty-third diode D23 and a twenty-fourth diode D24 are connected at two ends after the secondary side is connected in series to form a full-bridge rectifying circuit.
The fourth primary side input circuit comprises a seventh switch S7 and an eighth switch S8, wherein the eighth switch S8 is grounded, the seventh switch S7 and the eighth switch S8 are connected with one end of a fourth resonant inductor L4, the other end of the fourth resonant inductor L4 is connected with a fourth resonant capacitor C4, the other end of the fourth resonant capacitor C4 is connected with a primary side winding of a seventh transformer T7, the other end of the primary side winding of the seventh transformer T7 is connected with one end of the primary side winding of an eighth transformer T8, and the other end of the primary side winding of the eighth transformer T8 is connected with one end of the primary side winding of a tenth transformer T10 and one end of the primary side winding of a twelfth transformer T12 to form a second star connection point; the fourth secondary side output circuit is formed by connecting a secondary side of a seventh transformer T7 with a secondary side of a second transformer T2 in series, wherein the secondary side needs to keep a corresponding relation with a same name end of the primary side, and the thirteenth diode D12, the fourteenth diode D14, the third diode D3 and the fourth diode D4 are connected with two ends after being connected in series to form a full-bridge rectifying circuit.
The fifth primary input circuit comprises a ninth switch S9 and a tenth switch S10, wherein the tenth switch S10 is grounded, the ninth switch S9 and the tenth switch S10 are connected with one end of a fifth resonant inductor L5, the other end of the fifth resonant inductor L5 is connected with a fifth resonant capacitor C5, the other end of the fifth resonant capacitor C5 is connected with a primary winding of a ninth transformer T9, the other end of the primary winding of the ninth transformer T9 is connected with one end of the primary winding of the tenth transformer T10, and the other end of the primary winding of the tenth transformer T10 is connected with one end of the primary winding of an eighth transformer T8 and one end of the primary winding of a twelfth transformer T12 to form a second star connection point; the fifth secondary side output circuit is formed by connecting a secondary side of a ninth transformer T9 with a secondary side of a fourth transformer T4 in series, wherein the secondary side needs to keep a corresponding relation with a same name end of the primary side, and two ends after being connected in series are connected with a seventh diode D7, an eighth diode D8, a seventeenth diode D17 and a tenth eighth diode D18 to form a full-bridge rectifying circuit.
The sixth primary input circuit comprises an eleventh switch S11 and a twelfth switch S12, wherein the twelfth switch S12 is grounded, the eleventh switch S11 and the twelfth switch S12 are connected with one end of a sixth resonant inductor L6, the other end of the sixth resonant inductor L6 is connected with a sixth resonant capacitor C6, the other end of the sixth resonant capacitor C6 is connected with a primary winding of an eleventh transformer T11, the other end of the primary winding of the eleventh transformer T11 is connected with one end of the primary winding of the twelfth transformer T12, and the other end of the primary winding of the twelfth transformer T12 is connected with one end of the primary winding of an eighth transformer T8 and one end of the primary winding of a tenth transformer T10 to form a second star connection point; the sixth secondary side output circuit is formed by connecting a secondary side of an eleventh transformer T11 with a secondary side of a sixth transformer T6 in series, wherein the secondary side needs to keep a corresponding relation with a same name end of the primary side, and an eleventh diode D11, a twelfth diode D12, a twenty-first diode D21 and a twenty-second diode D22 are connected at two ends after the secondary side is connected in series to form a full-bridge rectifying circuit.
Meanwhile, describing the driving time sequence of the embodiment, the first primary side input circuit, the second primary side input circuit and the third primary side input circuit form a first star connection, the fourth primary side input circuit, the fifth primary side input circuit and the sixth primary side input circuit form a second star connection, the phase difference of driving signals of 3 bridge arms of each star connection is 120 degrees, and the phase difference of upper and lower tubes of the same bridge arm is 180 degrees; the phases of driving signals between the upper tubes and the corresponding upper tubes, and between the lower tubes and the corresponding lower tubes of the 3 bridge arms are the same, in a specific embodiment, the driving signals of the upper tubes and the lower tubes of the two bridge arms of different star LLC resonances, which are connected by the secondary side of the transformer in a cross manner, are the same, or the phases of the bridge arms are the same. In the embodiment, the input is positive 400VDC, 6 bridge arms on the primary side are connected between 400VDC and the ground potential, the upper tube and the lower tube of the 6 bridge arms are driven complementarily, and the 3 bridge arm drives forming star connection are sequentially different in phase by 120 degrees.
The primary sides of the two star-shaped connections of the first to sixth primary side input circuits are connected in parallel, and the first to sixth secondary side output circuits are connected in parallel after full-bridge rectification. Through the layout, the multipath interleaving parallel connection is realized, the input voltage Vi is added to 6 primary side input circuits and then is rectified and connected in parallel through 12 transformers to output to the output voltage Vo, and a filter capacitor C is further connected before the output voltage Vo, so that the multipath interleaving effectively reduces the pulsation of the output current.
In some alternative embodiments, 6 bridge arms of the 6-way LLC resonant circuit in the primary side input circuit are divided into two star-connected bridge arm groups, and the switching drive signals of 3 bridge arms in the star-connected bridge arm groups are identical in phase with respect to the drive signals of the other 3 bridge arms.
In some alternative embodiments, in the star connection bridge arm group, the secondary sides of the series transformers corresponding to the same phase bridge arm of each pair of switch driving signals are in cross series.
Fig. 6 is a schematic flow chart of a control method of a self-current-sharing high-frequency star LLC resonant combined transformation device according to this embodiment, which can be implemented by the self-current-sharing high-frequency star LLC resonant combined transformation device, and specifically includes the following steps:
in step 601, an input voltage is performed at an input end of a primary side input circuit, and the input voltage is controlled by two resonant switches, a coupling inductor and a resonant capacitor in an LLC resonant circuit of the primary side input circuit and then flows through primary sides of two series transformers to enter the series transformers.
The primary side input circuit comprises an LLC resonant circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonant circuit which is connected in the high-frequency star mode comprises an LLC resonant circuit which is more than or equal to two paths, and the LLC resonant circuit comprises: two resonant switches, a coupling inductor, a resonant capacitor and primary sides of two series transformers; after the coupling inductor, the resonance capacitor and the primary winding initial end of the series transformer are connected in series, one end of the coupling inductor is connected in series between the two resonance switches; in the LLC resonant circuit with high-frequency star connection, the primary winding termination ends of series transformers in the LLC resonant circuit are connected to form a star connection point.
In step 602, the input voltage is converted by the primary side of the series transformer in the high-frequency star-type connected LLC resonant circuit and then enters the secondary side output circuit.
The secondary side output circuit comprises an LLC resonance output circuit which is connected in a high-frequency star mode and is more than or equal to two paths, the LLC resonance output circuit which is connected in a high-frequency star mode comprises an LLC resonance output circuit which is more than or equal to two paths, the LLC resonance output circuit comprises two transformer secondary side output circuits of a series transformer, and the transformer secondary side output circuit comprises: the secondary side of the single transformer is connected with the output control and then connected to the power supply rectification output end.
And 603, outputting the current which is equalized through a power rectification output end in the secondary side output circuit.
Compared with the prior art, the scheme of the embodiment has high conversion efficiency, the ZVS of the switching tube in the full load range cannot be realized by adopting the phase-shifting full-bridge technology, the switching tube is turned off hard, and the secondary rectifying diode has reverse recovery, so that the efficiency is lower than that of the LLC resonant conversion technology.
The primary side of the embodiment adopts an LLC resonance transformation scheme, the primary side switching tube has zero voltage switching and small loss, and when the resonance parameter deviation of two star-shaped LLC resonance changes is larger, the self-current equalizing characteristic can reduce the total loss, and the efficiency is also improved properly; if the efficiency is not high, the output rectification can also be realized by using a Schottky diode, and the MOSFET synchronous rectification is adopted for pursuing higher efficiency.
By verifying through fig. 4 that the resonant inductance in the same-phase bridge arm is adopted for parallel output of two star-shaped LLC resonant transformations after being coupled in the same direction, when the resonant parameters of the two star-shaped LLC resonant transformations deviate from the central value, the output current difference of the two star-shaped LLC resonant transformations is basically zero, and the simulation result of the embodiment can be seen from fig. 5: the waveforms of the instantaneous values of the output currents of the two resonant transformations are completely coincident, namely the waveforms are the same, so that the good current sharing performance of the instantaneous currents and the average currents is realized, the loss can be reduced, the efficiency is improved, the voltage current stress and the thermal stress are reduced, and the reliability is improved to a certain extent.
In summary, the circuit of this embodiment adopts the mode of connecting the secondary sides in two transformers in series in the same phase bridge arm in two high-frequency star LLC resonant transformation in cross, the direct parallel connection of two high-frequency star LLC resonant transformation has a DCDC transformation structure, when the resonance parameters of two star LLC resonant transformation deviate from the central value, the output currents of two star LLC resonant are basically not different, the instantaneous waveforms of the output currents of two star LLC resonant coincide, the current equalizing performance of instantaneous current and average current is well realized, the loss can be reduced, the efficiency is improved, the voltage current stress and the thermal stress are reduced, and the reliability is improved to a certain extent.
The above is merely exemplary embodiments of the present invention, and the first to sixth primary input circuits may be connected in series with +400VDC and-400 VDC respectively, which are two primary inputs connected in star, and the scope of the present invention is not limited to the above embodiments.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of hardware associated with instructions of a computer program, which may be stored on a Digital Signal Processing (DSP) chip or a non-transitory computer readable storage medium, which when executed may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (SYNCHLINK) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.
Claims (6)
1. A self-current-sharing high-frequency star-type LLC resonance combined conversion device is characterized by comprising: the primary side input circuit and the secondary side output circuit are connected through a transformer;
The primary side input circuit comprises two paths of LLC resonant circuits connected in a high-frequency star mode, wherein the LLC resonant circuits connected in the high-frequency star mode comprise 6 paths of LLC resonant circuits, and the LLC resonant circuits comprise: two resonant switches, a coupling inductor, a resonant capacitor and primary sides of two series transformers; after the coupling inductor, the resonance capacitor and the primary winding initial end of the series transformer are connected in series, one end of the coupling inductor is connected between the two resonance switches in series; in the LLC resonant circuit connected in a high-frequency star mode, the primary winding termination end of the series transformer in the LLC resonant circuit is connected to form a star connection point; the 6 bridge arms of the LLC resonant circuit are divided into two groups of star-shaped connection bridge arm groups, the switching driving signals of 3 bridge arms in the star-shaped connection bridge arm groups are identical in phase relative to the driving signals of the other group of 3 bridge arms, and the secondary sides of the series transformers corresponding to the same-phase bridge arms of each pair of switching driving signals are in cross series connection;
The secondary side output circuit comprises two paths of LLC resonant output circuits which are connected in a star mode, the LLC resonant output circuits which are connected in a star mode comprise 6 paths of LLC resonant output circuits, the LLC resonant output circuits comprise two transformer secondary side output circuits of the series transformer, and the transformer secondary side output circuit comprises: the secondary side of the single transformer is connected with the output control and then connected to the power supply rectification output end; the primary sides of the series transformers in the primary side input circuit are connected in parallel, and the secondary sides of the single transformers in the secondary side output circuit are connected in parallel.
2. The self-equalizing high-frequency star LLC resonant combination converter of claim 1, wherein the two resonant switches of the LLC resonant circuit form legs of the high-frequency star-connected LLC resonant circuit, and the driving signals of the upper and lower tubes of each leg are 180 ° different in the primary side input circuit.
3. The self-equalizing high-frequency star LLC resonant combination converter of claim 1, wherein two resonant switches of said LLC resonant circuit form legs of said high-frequency star-connected LLC resonant circuit, and wherein the drive signals of different legs differ in phase by 120 ° in said primary side input circuit.
4. The self-equalizing high-frequency star-shaped LLC resonant combination transformation device according to claim 1, wherein the secondary side of each transformer is a full-bridge rectifying output circuit.
5. The self-current-sharing high-frequency star-shaped LLC resonant combination conversion device according to claim 1, wherein the output control is an output diode or a MOS tube.
6. A control method of a self-current-sharing high-frequency star-type LLC resonance combined conversion device is characterized by comprising the following steps:
input voltage is carried out at the input of primary side input circuit, primary side input circuit includes two way high frequency star connection's LLC resonant circuit, high frequency star connection's LLC resonant circuit includes 6 way LLC resonant circuit, LLC resonant circuit includes: two resonant switches, a coupling inductor, a resonant capacitor and primary sides of two series transformers; after the coupling inductor, the resonance capacitor and the primary winding initial end of the series transformer are connected in series, one end of the coupling inductor is connected between the two resonance switches in series; in the LLC resonant circuit connected in a high-frequency star mode, the primary winding termination end of the series transformer in the LLC resonant circuit is connected to form a star connection point; the 6 bridge arms of the LLC resonant circuit are divided into two groups of star-shaped connection bridge arm groups, the switching driving signals of 3 bridge arms in the star-shaped connection bridge arm groups are identical in phase relative to the driving signals of the other group of 3 bridge arms, and the secondary sides of the series transformers corresponding to the same-phase bridge arms of each pair of switching driving signals are in cross series connection;
The primary sides of the series transformers in the primary side input circuit are connected in parallel;
The input voltage passes through the primary side of the series transformer in the LLC resonant circuit connected in a high-frequency star mode, and enters a secondary side output circuit after being transformed by the transformer; the secondary side output circuit comprises two paths of LLC resonant output circuits which are connected in a star mode, the LLC resonant output circuits which are connected in a star mode comprise 6 paths of LLC resonant output circuits, the LLC resonant output circuits comprise two transformer secondary side output circuits of the series transformer, and the transformer secondary side output circuit comprises:
the secondary side of the single transformer is connected with the output control and then connected to the power supply rectification output end;
the secondary sides of the single transformers in the secondary side output circuit are connected in parallel;
and outputting the current which is equalized through the power supply rectification output end in the secondary side output circuit.
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