CN113726179B - Wide-voltage double-active full-bridge DC-DC converter and control method thereof - Google Patents

Wide-voltage double-active full-bridge DC-DC converter and control method thereof Download PDF

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CN113726179B
CN113726179B CN202111025261.5A CN202111025261A CN113726179B CN 113726179 B CN113726179 B CN 113726179B CN 202111025261 A CN202111025261 A CN 202111025261A CN 113726179 B CN113726179 B CN 113726179B
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full
bridge circuit
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tap
voltage
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CN113726179A (en
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李建国
张雅静
王久和
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Beijing Information Science and Technology University
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Beijing Information Science and Technology University
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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
    • H02M3/3353—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 at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
    • 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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The utility model provides a wide voltage double initiative full bridge DC-DC converter and control method thereof, it utilizes the relay of establishing ties between transformer secondary side coil each tap and secondary side full bridge circuit, carries out the turns switching of secondary side coil according to former secondary side voltage ratio. And the inductance current optimizing control unit is utilized to adjust the phase shift angle between different switching elements in the primary and secondary full-bridge circuits according to the voltage transformation ratio k corresponding to the current conducted tap, with the aim of minimizing the inductance peak current and meeting the boundary condition of the transmission power. Therefore, when the direct current voltage ratio is not matched with the physical transformation ratio of the high-frequency transformer, the loss of larger reflux power and current stress on the working efficiency of the converter is overcome, the control complexity on the phase shift angle is simplified, the primary and secondary side full-bridge output voltage ratio vh1/vh2 can be matched with the physical transformation ratio n 1/(n 21, n22, n 23) of the high-frequency transformer through the scheduling of the phase shift angle in one switching period, the current is optimized, and the influence of the inductance peak current on the working efficiency of the converter is reduced.

Description

Wide-voltage double-active full-bridge DC-DC converter and control method thereof
Technical Field
The application relates to the technical field of power electronics, in particular to a wide-voltage double-active full-bridge DC-DC converter and a control method thereof.
Background
The double-active full-bridge DC-DC converter usually adopts a phase-shift control method under the limitation of switching frequency. The single phase shift control method has the advantages of simplicity and easiness in implementation, but when the direct current voltage ratio is not matched with the physical transformation ratio of the high-frequency transformer, larger reflux power and current stress exist, and the efficiency of the converter is reduced.
Aiming at the problem that the reflux power and the current stress influence the efficiency of the converter, related researches sequentially provide control methods of extended phase shifting, double phase shifting and triple phase shifting, so that the reflux power and the current stress are reduced to a great extent, and the efficiency of the converter is improved.
However, in each of the control methods described above, the phase shift angle needs to be calculated by using different calculation formulas according to different voltage ratios (k > 1, k < 1, and k=1), and the calculation process is complicated. The existing control method has higher operation requirement on passive phase shift control and has high operation cost. In addition, in the prior art, when the direct current voltage ratio is seriously deviated from the physical transformation ratio of the high frequency transformer, the efficiency of the converter is still to be improved.
Disclosure of Invention
Aiming at the defects of the prior art, the application provides the wide-voltage double-active full-bridge DC-DC converter and the control method thereof. The application specifically adopts the following technical scheme.
First, to achieve the above object, a wide-voltage dual-active full-bridge DC-DC converter is proposed, which includes: the voltage conversion circuit and the control unit connected with the voltage conversion circuit. The voltage conversion circuit includes: the primary side full-bridge circuit, the secondary side full-bridge circuit, an inductor L1 connected between the primary side full-bridge circuit and the secondary side full-bridge circuit, a multi-tap high-frequency transformer T1 and a relay corresponding to each tap of the multi-tap high-frequency transformer T1; the inductor L1 is connected in series with the primary side coil of the multi-tap high-frequency transformer T1, each tap of the secondary side coil of the multi-tap high-frequency transformer T1 is connected in series with the switch paths of each relay, each tap is connected to the secondary side full bridge through a common end between the switch paths of each relay, and each relay controls each tap on or off of the secondary side of the multi-tap high-frequency transformer T1 through the switch paths of each relay. The control unit includes: a primary-secondary side voltage ratio calculation unit for calculating the primary-side full-bridge voltage according to the input voltage v of the primary-side full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 Calculating the primary-secondary side voltage ratio, and determining secondary side taps matched with the primary-secondary side voltage ratio according to the ratio of the number of turns of a primary side coil to the number of turns of a coil corresponding to each tap of a secondary side coil in the multi-tap high-frequency transformer T1; the tap driving circuit is connected with the primary and secondary side voltage ratio calculation unit and each relay and is used for correspondingly driving the relay switch channels connected with the tap to be conducted according to the secondary side tap determined by the primary and secondary side voltage ratio calculation unit and driving the relay switch channels connected with other taps to be turned off; a passive phase-shifting control unit for collecting input voltage v of primary full-bridge circuit 1 Input current i of primary side full bridge circuit 1 Output voltage v of secondary full bridge circuit 2 Output current of secondary full bridge circuiti 2 According to the voltage reference value v of the secondary full-bridge circuit 2 * Capacitance value C of secondary full bridge circuit 2 And a conductance value G 2 And damping coefficient g of switching element in secondary full bridge circuit 22 Calculating passive control parameters
Figure BDA0003243123020000021
Then the initial phase shift angle duty ratio D of the primary side full-bridge circuit and the secondary side full-bridge circuit is calculated according to the passive control parameter K,
Figure BDA0003243123020000022
wherein f s The switching frequency of a switching element in a primary full-bridge circuit and a secondary full-bridge circuit is L1 which is an inductance value connected with a primary coil of the multi-tap high-frequency transformer T1, and N which is a transformation ratio corresponding to a tap of the multi-tap high-frequency transformer T1 which is conducted currently; the inductance current optimization control unit is used for respectively calculating according to the voltage transformation ratio k corresponding to the tap of the multi-tap high-frequency transformer T1 which is conducted currently: calculating a first phase shift angle D1 corresponding to two switching elements in the primary full-bridge circuit, calculating a second phase shift angle D2 corresponding to a switching element connected between a circuit input end and an inductance coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil starting end in the secondary full-bridge circuit, and calculating a third phase shift angle D3 corresponding to a switching element connected between a circuit input end and an inductance coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil terminal end in the secondary full-bridge circuit, driving each switching element to switch the switching states according to the corresponding phase shift angles, wherein when the primary phase shift angle duty ratio is smaller than the primary phase shift angle duty ratio>
Figure BDA0003243123020000031
When (I)>
Figure BDA0003243123020000032
When the initial phase shift angle duty cycle +.>
Figure BDA0003243123020000033
When (I)>
Figure BDA0003243123020000034
D 3 ＝D 2 。
Optionally, the wide-voltage dual-active full-bridge DC-DC converter according to any one of the preceding claims, wherein the primary full-bridge circuit includes a left bridge arm and a right bridge arm that are jointly composed of four switching elements, and the left bridge arm includes: the primary full-bridge circuit comprises a primary full-bridge circuit, a primary switching element S1, a secondary switching element S2 and a secondary switching element, wherein the primary switching element S1 is connected between a first input end of the primary full-bridge circuit and a starting end of an inductance coil connected with the primary full-bridge circuit; the right bridge arm includes: a third primary switching element S3 connected between the second input terminal of the primary full-bridge circuit and the start terminal of the inductor coil connected to the primary full-bridge circuit, and a fourth primary switching element S4 connected between the second input terminal of the primary full-bridge circuit and the end terminal of the primary coil connected to the primary full-bridge circuit; the first primary side switching element S1 and the fourth primary side switching element S4 are switched to be in on-off state according to a first phase shift angle D1, and the second primary side switching element S2 and the third primary side switching element S3 are switched to be in on-off state according to an initial phase shift angle duty ratio D.
Optionally, the wide-voltage dual-active full-bridge DC-DC converter according to any one of the preceding claims, wherein the secondary full-bridge circuit includes: a first secondary side switching element S5 connected between the first output terminal of the secondary side full bridge circuit and the common terminal of each relay switch path; a second secondary switching element S6 connected between the first output terminal of the secondary full-bridge circuit and the terminal of the secondary coil to which the secondary full-bridge circuit is connected; a third secondary side switching element S7 connected between the secondary side full bridge circuit second output terminal and the relay switch path common terminal; and a fourth secondary switching element S8 connected between the second output terminal of the secondary full-bridge circuit and the terminal of the secondary coil to which the secondary full-bridge circuit is connected.
Optionally, the wide-voltage dual-active full-bridge DC-DC converter according to any one of the above claims, wherein the secondary winding of the multi-tap high-frequency transformer T1 includes three taps, and the three taps are respectively connected with the switching paths of the three relays in seriesA first tap corresponding to the number of turns of the secondary coil of n 21 The number of turns of the secondary coil corresponding to the second tap is n 22 The number of turns of the secondary coil corresponding to the third tap is n 23 ，n 21 ＞n 22 ＞n 23 。
Optionally, the wide-voltage double-active full-bridge DC-DC converter according to any one of the above claims, wherein the primary-secondary side voltage ratio calculating unit calculates the primary-side full-bridge voltage according to the input voltage v of the primary-side full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 Calculating the primary-secondary side voltage ratio
Figure BDA0003243123020000041
Then according to the number n of turns of the primary coil in the multi-tap high-frequency transformer T1 1 The ratio of the number of coil turns corresponding to each tap of the secondary coil is determined as follows to match the secondary tap required by the primary-to-secondary voltage ratio: when the primary-secondary side voltage ratio k v1 <n 1 /n 21 Selecting a first tap; when the primary-secondary side voltage is greater than n 1 /n 21 <k v1 <n 1 /n 22 Selecting a second tap; when the primary-secondary side voltage ratio k v1 <n 1 /n 23 When a third tap is selected.
Optionally, the wide-voltage double-active full-bridge DC-DC converter according to any one of the above claims is characterized in that the maximum turns ratio of the primary coil to the secondary coil in the multi-tap high-frequency transformer T1 satisfies v 2max /v 1min Wherein v is 1min Is the minimum value of the input voltage of the primary coil, v 2max Is the maximum value of the secondary coil output voltage.
Meanwhile, to achieve the above object, the present application further provides a control method of a wide-voltage double-active full-bridge DC-DC converter, which is used for the wide-voltage double-active full-bridge DC-DC converter as described in any one of the above, and the steps thereof include: first, according to the input voltage v of the primary full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 Calculating the primary-secondary side voltage ratio and according to the number of turns of the primary side coil and the secondary side in the multi-tap high-frequency transformer T1Determining secondary side taps which are matched with the primary secondary side voltage ratio requirement according to the coil turns ratio corresponding to each tap of the coil; the second step, correspondingly driving the relay switch channels connected with the secondary side tap to be conducted according to the secondary side tap determined in the first step, and driving the relay switch channels connected with other taps to be turned off; step three, collecting input voltage v of primary full-bridge circuit 1 Input current i of primary side full bridge circuit 1 Output voltage v of secondary full bridge circuit 2 Output current i of secondary full bridge circuit 2 According to a preset voltage reference value v of the secondary full-bridge circuit 2 * Capacitance value C of secondary full bridge circuit 2 And a conductance value G 2 And damping coefficient g of switching element in secondary full bridge circuit 22 Calculating passive control parameters
Figure BDA0003243123020000051
Then, according to the passive control parameter K, calculating the initial phase shift angle duty ratio D of the primary side full bridge circuit and the secondary side full bridge circuit, < ->
Figure BDA0003243123020000052
Wherein f s The switching frequency of a switching element in a primary full-bridge circuit and a secondary full-bridge circuit is L1 which is an inductance value connected with a primary coil of the multi-tap high-frequency transformer T1, and N which is a transformation ratio corresponding to a tap of the multi-tap high-frequency transformer T1 which is conducted currently; fourth, according to the voltage transformation ratio k corresponding to the tap of the multi-tap high-frequency transformer T1 which is conducted currently, respectively calculating: calculating a first phase shift angle D1 between two switching elements at the starting end of a left bridge arm and the tail end of a right bridge arm in the primary full-bridge circuit, calculating a second phase shift angle D2 between the switching element connected between the circuit input end and the starting end of an inductance coil in the primary full-bridge circuit and the switching element connected between the circuit output end and the starting end of a secondary coil in the secondary full-bridge circuit, and calculating a third phase shift angle D3 between the switching element connected between the circuit input end and the starting end of the inductance coil in the primary full-bridge circuit and the switching element connected between the circuit output end and the terminal of the secondary coil in the secondary full-bridge circuit, and driving each switching element to switch according to the corresponding phase shiftChanging, wherein, when the phase angle is initially shifted, the duty cycle is +>
Figure BDA0003243123020000053
When (I)>
Figure BDA0003243123020000054
At the initial phase shift angle duty cycle
Figure BDA0003243123020000055
When (I)>
Figure BDA0003243123020000056
D 3 ＝D 2 。
Optionally, the control method of the wide-voltage double-active full-bridge DC-DC converter according to any one of the above is characterized in that in the first step, according to the input voltage v of the primary full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 The calculated primary-secondary side voltage ratio is
Figure BDA0003243123020000061
Optionally, the control method of the wide-voltage double-active full-bridge DC-DC converter according to any one of the above claims is characterized in that in the first step, the number of turns n of the primary winding in the multi-tap high-frequency transformer T1 is specifically determined according to the following steps 1 The ratio of the number of coil turns corresponding to each tap of the secondary coil determines the secondary tap matching the primary-secondary voltage ratio requirement: when the primary-secondary side voltage ratio k v1 <n 1 /n 21 Selecting a first tap; when the primary-secondary side voltage is greater than n 1 /n 21 <k v1 <n 1 /n 22 Selecting a second tap; when the primary-secondary side voltage ratio k v1 <n 1 /n 23 When a third tap is selected.
Optionally, the control method of the wide-voltage dual-active full-bridge DC-DC converter according to any one of the preceding claims, wherein the voltage reference v2 of the secondary full-bridge circuit is set through an interface or set through remote communication.
Advantageous effects
The relay switch path connected in series between each tap of the secondary side coil of the multi-tap high-frequency transformer and the secondary side full-bridge circuit is utilized, and the number of turns of the secondary side coil is switched according to the original secondary side voltage ratio so as to improve the matching degree of the direct current voltage ratio and the physical transformation ratio of the transformer. In addition, the inductance current optimizing control unit adjusts the phase shift angle between different switching elements in the primary and secondary full-bridge circuits according to the voltage transformation ratio k corresponding to the current conducted tap and with the minimum inductance peak current and the boundary condition of the transmission power as targets. Therefore, when the direct current voltage ratio is not matched with the physical transformation ratio of the high-frequency transformer, the loss of larger reflux power and current stress to the working efficiency of the transformer can be effectively overcome, the control complexity of phase shifting angle is simplified, the primary and secondary full-bridge output voltage ratio vh1/vh2 can be matched with the physical transformation ratio n 1/(n 21, n22, n 23) of the high-frequency transformer through the scheduling of the phase shifting angle in one switching period, and therefore the current is optimized, and the influence of inductance peak current to the working efficiency of the transformer is reduced.
Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.
Drawings
The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate and explain the application and do not limit it. In the drawings:
FIG. 1 is a schematic circuit diagram of a wide voltage dual active full bridge DC-DC converter of the present application;
FIG. 2 is a flow chart of a control method of the wide voltage dual active full bridge DC-DC converter of the present application;
fig. 3 is a schematic diagram of the connection mode of the passive phase shift control unit and the current optimization control unit in the present application.
Detailed Description
In order to make the objects and technical solutions of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings of the embodiments of the present application. It will be apparent that the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without the benefit of the present disclosure, are intended to be within the scope of the present application based on the described embodiments.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "and/or" as referred to in this application means that each exists alone or both.
As used herein, "connected" means either a direct connection between elements or an indirect connection between elements via other elements.
Fig. 1 is a voltage conversion circuit used in a wide voltage double-active full-bridge DC-DC converter according to the present application. The voltage conversion circuit includes:
the primary side full-bridge circuit, the secondary side full-bridge circuit, an inductor L1 connected between the primary side full-bridge circuit and the secondary side full-bridge circuit, a multi-tap high-frequency transformer T1 and a relay corresponding to each tap of the multi-tap high-frequency transformer T1;
wherein the inductor L1 is connected in series with the primary winding of the multi-tap high frequency transformer T1,
each tap of the secondary coil of the multi-tap high-frequency transformer T1 is respectively connected with the switch paths of each relay in series, each tap is respectively connected to the secondary full bridge through a common end among the switch paths of each relay, and each relay respectively controls the on or off of each tap of the secondary coil of the multi-tap high-frequency transformer T1 through the switch paths of each relay
And to ensure that the voltage-to-transformation ratio matches the input-to-output voltage,the maximum turns ratio of primary and secondary windings in the multi-tap high frequency transformer T1 can be based on the minimum v of the input voltage of the primary winding 1min With the maximum value of the secondary coil output voltage being v 2max And is designed according to the maximum voltage ratio to ensure the transformation efficiency: the maximum turns ratio n1/n21 of the primary coil and the secondary coil in the multi-tap high frequency transformer T1 can be set to satisfy
Figure BDA0003243123020000081
For the voltage conversion circuit, the control unit shown in the lower part of fig. 3 is utilized, the control unit is arranged, the control step shown in fig. 2 is adopted, the control of the DC-DC converter is realized, the turn number of the secondary coil can be switched according to the primary-secondary voltage ratio to improve the matching degree of the direct-current voltage ratio and the physical transformation ratio of the transformer, the inductance current optimization control unit is further utilized on the basis, the phase shift angle between different switching elements in the primary-secondary full-bridge circuit is adjusted according to the voltage transformation ratio k corresponding to the tap which is conducted currently, the inductance peak current is minimum, and the boundary condition of transmission power is met. Therefore, when the direct current voltage ratio is not matched with the physical transformation ratio of the high-frequency transformer, the loss of larger reflux power and current stress to the working efficiency of the transformer can be effectively overcome, the control complexity of phase shifting angle is simplified, the primary and secondary full-bridge output voltage ratio vh1/vh2 can be matched with the physical transformation ratio n 1/(n 21, n22, n 23) of the high-frequency transformer through the scheduling of the phase shifting angle in one switching period, and therefore the current is optimized, and the influence of inductance peak current to the working efficiency of the transformer is reduced.
The control unit for the voltage conversion circuit in fig. 3 may be specifically configured to include:
the primary-secondary side voltage ratio calculating unit is used for calculating a primary-secondary side voltage ratio according to the input voltage v1 of the primary-side full-bridge circuit and the output voltage v2 of the current required secondary-side full-bridge circuit after corresponding analog quantity and digital quantity in the circuit are acquired, and determining a secondary side tap matched with the requirement of the primary-secondary side voltage ratio according to the ratio of the number of turns of a primary side coil to the number of turns of coils corresponding to each tap of a secondary side coil in the multi-tap high-frequency transformer T1;
the tap driving circuit is connected with the primary and secondary side voltage ratio calculation unit and each relay and is used for correspondingly driving the relay switch channels connected with the tap to be conducted according to the secondary side tap determined by the primary and secondary side voltage ratio calculation unit and driving the relay switch channels connected with other taps to be turned off, so that the secondary side coil tap is switched;
the passive phase-shifting control unit acquires an input voltage v1 of the primary full-bridge circuit, an input current i1 of the primary full-bridge circuit, an output voltage v2 of the secondary full-bridge circuit and an output current i2 of the secondary full-bridge circuit, calculates a passive control parameter according to a voltage reference value v2 of the secondary full-bridge circuit, a capacitance value C2 and a conductance value G2 of the secondary full-bridge circuit and a damping coefficient G22 of a switching element in the secondary full-bridge circuit
Figure BDA0003243123020000091
Then, according to the passive control parameter K, calculating the initial phase shift angle duty ratio D of the primary side full bridge circuit and the secondary side full bridge circuit, < ->
Figure BDA0003243123020000092
Wherein fs is the switching frequency of the switching element in the primary full-bridge circuit and the secondary full-bridge circuit, L1 is the inductance value connected with the primary coil of the multi-tap high-frequency transformer T1, N is the transformation ratio corresponding to the tap of the multi-tap high-frequency transformer T1 which is currently conducted, and v is the voltage reference value of the secondary full-bridge circuit 2 * The specific numerical values of the converter control interface can be set correspondingly according to the input options of the converter control interface, or preset is realized in a remote communication mode;
the inductance current optimization control unit is used for respectively calculating according to the voltage transformation ratio k corresponding to the tap of the multi-tap high-frequency transformer T1 which is conducted currently: calculating a first phase shift angle D1 corresponding to two switching elements in the primary full-bridge circuit, calculating a second phase shift angle D2 corresponding to a switching element connected between a circuit input end and an inductance coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil starting end in the secondary full-bridge circuit, and calculating a third phase shift angle D3 corresponding to a switching element connected between a circuit input end and an inductance coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil terminal end in the secondary full-bridge circuit, driving each switching element to switch the switching states according to the corresponding phase shift angles,
at the initial phase shift angle duty cycle
Figure BDA0003243123020000101
When (I)>
Figure BDA0003243123020000102
At the initial phase shift angle duty cycle
Figure BDA0003243123020000103
When (I)>
Figure BDA0003243123020000104
The method can switch the turns ratio between the primary coil and the secondary coil of the transformer through the relay, so that the direct-current voltage ratio is close to the physical transformation ratio of the high-frequency transformer, and the voltage transformation ratio efficiency of the transformer is improved; then, the control of the voltage and the power by the passive phase-shifting control unit further ensures that the initial phase-shifting angle duty ratio D is accurately matched with the reflux stress, and the efficiency of the converter is improved; finally, the inductance current is further optimized through the adjustment of the phase shift angle between the switching elements by the inductance current optimizing control unit, so that the inductance peak current is minimum, and the boundary condition of the transmission power is met, so that the power transmission efficiency of the converter is improved.
Referring specifically to fig. 1, the secondary winding of the multi-tap high frequency transformer T1 may be configured to include three taps connected in series with the switching paths of the three relays, respectively, wherein the number of turns of the secondary winding corresponding to the first tap is n 21 The number of turns of the secondary coil corresponding to the second tap is n 22 The number of turns of the secondary coil corresponding to the third tap is n 23 ，n 21 ＞n 22 ＞n 23 . The primary-secondary side voltage ratio calculating unit can calculate the primary-side full-bridge voltage according to the input voltage v 1 Output voltage v of secondary full-bridge circuit required currently 2 Calculating the primary and secondary side voltage ratio
Figure BDA0003243123020000111
Then according to the number n of turns of the primary coil in the multi-tap high-frequency transformer T1 1 The ratio of the number of turns of the coil corresponding to each tap of the secondary coil>
Figure BDA0003243123020000112
The secondary tap matching the primary secondary voltage ratio requirement is determined as follows:
when the primary-secondary side voltage ratio k v1 <n 1 /n 21 When the first tap is selected, the inductance current optimization control unit performs the current-switching on according to the voltage transformation ratio k=n corresponding to the first tap of the multi-tap high-frequency transformer T1 21 *v 1 /n 1 *v 2 >1, respectively calculating phase shift angles among switching elements;
when the primary-secondary side voltage is greater than n 1 /n 21 <k v1 <n 1 /n 22 At this time, the inductance current optimization control unit selects the second tap according to the voltage transformation ratio k=n corresponding to the second tap of the multi-tap high-frequency transformer T1 which is currently turned on 22 *v 1 /n 1 *v 2 Respectively calculating phase shift angles among the switching elements;
when the primary-secondary side voltage ratio k v1 <n 1 /n 23 At this time, the inductance current optimization control unit selects the third tap according to the voltage transformation ratio k=n corresponding to the third tap of the multi-tap high-frequency transformer T1 which is currently turned on 23 *v 1 /n 1 *v 2 The phase shift angle between the switching elements is calculated separately.
In the manner shown in fig. 3, the primary full-bridge circuit of the dual active full-bridge DC-DC converter may specifically be configured to include a left bridge arm and a right bridge arm that are formed by four switching elements, where the left bridge arm includes: the primary full-bridge circuit comprises a primary full-bridge circuit, a primary switching element S1, a secondary switching element S2 and a secondary switching element, wherein the primary switching element S1 is connected between a first input end of the primary full-bridge circuit and a starting end of an inductance coil connected with the primary full-bridge circuit;
the right bridge arm includes: a third primary switching element S3 connected between the second input terminal of the primary full-bridge circuit and the start terminal of the inductor coil connected to the primary full-bridge circuit, and a fourth primary switching element S4 connected between the second input terminal of the primary full-bridge circuit and the end terminal of the primary coil connected to the primary full-bridge circuit;
the on-off state is switched by the inductor current optimizing control unit according to the first phase shift angle D1 between the first primary side switching element S1 and the fourth primary side switching element S4, and the on-off state is switched by the inductor current optimizing control unit according to the initial phase shift angle duty ratio D between the second primary side switching element S2 and the third primary side switching element S3.
The secondary full-bridge circuit in the double-active full-bridge DC-DC converter can also comprise 4 switching elements, which are symmetrical to the primary full-bridge circuit:
a first secondary side switching element S5 connected between the first output terminal of the secondary side full bridge circuit and the common terminal of each relay switch path;
a second secondary switching element S6 connected between the first output terminal of the secondary full-bridge circuit and the terminal of the secondary coil to which the secondary full-bridge circuit is connected;
a third secondary side switching element S7 connected between the secondary side full bridge circuit second output terminal and the relay switch path common terminal;
and a fourth secondary switching element S8 connected between the second output terminal of the secondary full-bridge circuit and the terminal of the secondary coil to which the secondary full-bridge circuit is connected.
The passive phase shift control for this circuit can be specifically designed as:
(1) According to the parameters of the switching element, the loss of the primary and secondary full bridge is respectively equivalent to the conductance G1 and G2, and the system passivity is satisfied.
(2) From passive control, get
Figure BDA0003243123020000121
I in 2 And v 2 Current and voltage of secondary full bridge, v 1 V is the voltage of the primary full bridge 2 * C is the reference value of the secondary full-bridge voltage 2 And G 2 Capacitance and conductance values g of the secondary full bridge respectively 22 Is a passively controlled damping coefficient.
Therefore, according to the calculation result of K, the phase shift angle duty ratio D of the primary and secondary full bridge can be obtained to meet
Figure BDA0003243123020000122
F in s For switching frequency, L 1 Is the inductance value, N is the transformation ratio N between the primary coil and the secondary coil of the transformer gating 1 /n 21 ，n 1 /n 22 Or n 1 /n 23 。
Therefore, matching between the direct-current voltage ratio and the physical transformation ratio of the high-frequency transformer can be further realized through an inductance current optimization control step, and the equivalent of average significance is realized in one switching period:
(1) Record D 1 Is S 4 And S is 1 Is recorded as D 2 Is S 5 And S is 1 Is recorded as D 3 Is S 8 And S is 1 By varying the phase shift angle D 1 ,D 2 And D 3 So that the primary-secondary full-bridge output voltage ratio vh within one switching period 1 /vh 2 Physical transformation ratio n with high-frequency transformer 1 /(n 21 ,n 22 ,n 23 ) Equal, optimizing the current.
(2) The objective of the optimization is to minimize the inductive peak current and to meet the boundary conditions of the transmission power. The lagrangian conditional extremum equation is established as,
E＝i p +μ(p-p*) (3)
where ip is the per unit value of the peak inductance current, p and p are the per unit value and the target value of the transmission power, respectively, μ is the Lagrangian multiplier, and partial differentiation is performed on the phase shift angles D1, D2 and D3, respectively, to obtain
Figure BDA0003243123020000131
Substituting the inductive peak current expression and the transmission power expression obtained by the sectional integration calculation, and approximately replacing p with the phase shift angle D, namely, p=D (1-D) ≡D, to obtain phase shift angles D1, D2 and D3 respectively,
Figure BDA0003243123020000132
when->
Figure BDA0003243123020000133
Time (5)
Figure BDA0003243123020000134
When->
Figure BDA0003243123020000135
Time (6)
Where k=n21×v1/n1×v2>1 is the strobe first tap J 1 The corresponding converted voltage transformation ratio is obtained when other taps are turned on, and the k value is correspondingly converted according to the voltage transformation ratio of the taps.
Therefore, the transformer tap is changed, the turn ratio is changed, the voltage waveform (square wave, trapezoidal wave or three-level wave) of vh1 or vh2 is changed by optimizing current, so that the ratio of vh1 to vh2 is equal to the turn ratio of the transformer in one switching period, the peak inductance current can be optimized, and the influence of the peak inductance current on the working efficiency of the transformer is reduced.
The foregoing is merely exemplary of embodiments of the present application and is thus not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application.

Claims (8)

1. A wide voltage dual active full bridge DC-DC converter comprising: a voltage conversion circuit and a control unit connected to the voltage conversion circuit;
the voltage conversion circuit includes:
a primary full-bridge circuit, a secondary full-bridge circuit, an inductor (L1) connected between the primary full-bridge circuit and the secondary full-bridge circuit, a multi-tap high-frequency transformer (T1) and a relay corresponding to each tap of the multi-tap high-frequency transformer (T1);
the primary coil of the inductance (L1) and the secondary coil of the multi-tap high-frequency transformer (T1) are connected in series, each tap of the secondary coil of the multi-tap high-frequency transformer (T1) is connected in series with a switch path of each relay, each tap is connected to a secondary full bridge through a common end among the switch paths of each relay, and each relay controls each tap on or off of the secondary of the multi-tap high-frequency transformer (T1) through the switch path of each relay;
the control unit includes:
a primary-secondary side voltage ratio calculation unit for calculating the primary-side full-bridge voltage according to the input voltage v of the primary-side full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 Calculating the primary-secondary side voltage ratio, and determining secondary side taps matched with the primary-secondary side voltage ratio according to the ratio of the number of turns of a primary side coil to the number of turns of a coil corresponding to each tap of a secondary side coil in the multi-tap high-frequency transformer (T1);
the tap driving circuit is connected with the primary and secondary side voltage ratio calculation unit and each relay and is used for correspondingly driving the relay switch channels connected with the tap to be conducted according to the secondary side tap determined by the primary and secondary side voltage ratio calculation unit and driving the relay switch channels connected with other taps to be turned off;
a passive phase-shifting control unit for collecting input voltage v of primary full-bridge circuit 1 Input current i of primary side full bridge circuit 1 Output voltage v of secondary full bridge circuit 2 Output current i of secondary full bridge circuit 2 According to the voltage reference value v of the secondary full-bridge circuit 2 * Capacitance value C of secondary full bridge circuit 2 And a conductance value G 2 ToDamping coefficient g of switching element in secondary full bridge circuit 22 Calculating passive control parameters
Figure FDA0004285459930000011
Then, according to the passive control parameter K, calculating the initial phase shift angle duty ratio D of the primary side full bridge circuit and the secondary side full bridge circuit, < ->
Figure FDA0004285459930000012
Wherein f s The switching frequency of a switching element in a primary full-bridge circuit and a secondary full-bridge circuit is L1 which is an inductance value connected with a primary coil of a multi-tap high-frequency transformer (T1), and N which is a transformation ratio corresponding to a tap of the multi-tap high-frequency transformer (T1) which is conducted currently;
the inductance current optimization control unit is used for respectively calculating according to the voltage transformation ratio k corresponding to the tap of the multi-tap high-frequency transformer (T1) which is conducted currently: calculating a first phase shift angle D1 corresponding to two switching elements in the primary full-bridge circuit, calculating a second phase shift angle D2 corresponding to a switching element connected between a circuit input end and an inductance coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil starting end in the secondary full-bridge circuit, and calculating a third phase shift angle D3 corresponding to a switching element connected between a circuit input end and an inductance coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil terminal end in the secondary full-bridge circuit, driving each switching element to switch the switching states according to the corresponding phase shift angles,
at the initial phase shift angle duty cycle
Figure FDA0004285459930000021
When (I)>
Figure FDA0004285459930000022
At the initial phase shift angle duty cycle
Figure FDA0004285459930000023
When (I)>
Figure FDA0004285459930000024
2. The wide voltage dual active full bridge DC-DC converter of claim 1 wherein the primary full bridge circuit comprises a left leg and a right leg that are collectively comprised of four switching elements, wherein the left leg comprises: the primary full-bridge circuit comprises a primary full-bridge circuit, a primary switching element (S1) and a secondary switching element (S2), wherein the primary switching element is connected between a first input end of the primary full-bridge circuit and a starting end of an inductance coil connected with the primary full-bridge circuit;
the right bridge arm includes: the third primary side switching element (S3) is connected between the second input end of the primary side full-bridge circuit and the starting end of the inductance coil connected with the primary side full-bridge circuit, and the fourth primary side switching element (S4) is connected between the second input end of the primary side full-bridge circuit and the terminal end of the primary side coil connected with the primary side full-bridge circuit;
the first primary side switching element (S1) and the fourth primary side switching element (S4) are switched to be in on-off state according to a first phase shift angle D1, and the second primary side switching element (S2) and the third primary side switching element (S3) are switched to be in on-off state according to an initial phase shift angle duty ratio D.
3. The wide voltage dual active full bridge DC-DC converter of claim 2, wherein the secondary full bridge circuit comprises:
a first secondary side switching element (S5) connected between the first output terminal of the secondary side full bridge circuit and the common terminal of each relay switch path;
a second secondary switching element (S6) connected between the first output terminal of the secondary full-bridge circuit and the terminal of the secondary coil to which the secondary full-bridge circuit is connected;
a third secondary side switching element (S7) connected between the secondary side full-bridge circuit second output terminal and the relay switch path common terminal;
and a fourth secondary switching element (S8) connected between the second output terminal of the secondary full-bridge circuit and the terminal of the secondary coil to which the secondary full-bridge circuit is connected.
4. A wide voltage double active full bridge DC-DC converter as claimed in claim 3, characterized in that the secondary winding of the multi-tap high frequency transformer (T1) comprises three taps connected in series with the switching paths of the three relays, respectively, wherein the secondary winding corresponding to the first tap has a number of turns n 21 The number of turns of the secondary coil corresponding to the second tap is n 22 The number of turns of the secondary coil corresponding to the third tap is n 23 ，n 21 ＞n 22 ＞n 23 。
5. The wide-voltage double-active full-bridge DC-DC converter according to claim 4, characterized in that the maximum turns ratio of primary coil to secondary coil in the multi-tap high-frequency transformer (T1) satisfies v 2max /v 1min Wherein v is 1min Is the minimum value of the input voltage of the primary coil, v 2max Is the maximum value of the secondary coil output voltage.
6. A control method for a wide-voltage double-active full-bridge DC-DC converter according to any one of claims 1 to 5, comprising the steps of:
first, according to the input voltage v of the primary full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 Calculating the primary-secondary side voltage ratio, and determining secondary side taps matched with the primary-secondary side voltage ratio according to the ratio of the number of turns of a primary side coil to the number of turns of a coil corresponding to each tap of a secondary side coil in the multi-tap high-frequency transformer (T1);
the second step, correspondingly driving the relay switch channels connected with the secondary side tap to be conducted according to the secondary side tap determined in the first step, and driving the relay switch channels connected with other taps to be turned off;
step three, collecting input voltage v of primary full-bridge circuit 1 Input current i of primary side full bridge circuit 1 Output voltage v of secondary full bridge circuit 2 Output current i of secondary full bridge circuit 2 According to a preset voltage reference value v of the secondary full-bridge circuit 2 * Capacitance value C of secondary full bridge circuit 2 And a conductance value G 2 And damping coefficient g of switching element in secondary full bridge circuit 22 Calculating passive control parameters
Figure FDA0004285459930000041
Then, according to the passive control parameter K, calculating the initial phase shift angle duty ratio D of the primary side full bridge circuit and the secondary side full bridge circuit, < ->
Figure FDA0004285459930000042
Wherein f s The switching frequency of a switching element in a primary full-bridge circuit and a secondary full-bridge circuit is L1 which is an inductance value connected with a primary coil of a multi-tap high-frequency transformer (T1), and N which is a transformation ratio corresponding to a tap of the multi-tap high-frequency transformer (T1) which is conducted currently;
fourth, according to the voltage transformation ratio k corresponding to the tap of the multi-tap high-frequency transformer (T1) which is conducted currently, respectively calculating: calculating a first phase shift angle D1 corresponding to two switching elements at the starting end and the tail end of a left bridge arm in the primary full-bridge circuit, calculating a second phase shift angle D2 corresponding to a switching element connected between a circuit input end and an induction coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil starting end in the secondary full-bridge circuit, calculating a third phase shift angle D3 corresponding to a switching element connected between a circuit input end and an induction coil starting end in the primary full-bridge circuit and a switching element connected between a circuit output end and a secondary coil terminal in the secondary full-bridge circuit, driving each switching element to switch the switching states according to the corresponding phase shift, wherein,
at the initial phase shift angle duty cycle
Figure FDA0004285459930000043
When (I)>
Figure FDA0004285459930000044
At the initial phase shift angle duty cycle
Figure FDA0004285459930000045
When (I)>
Figure FDA0004285459930000046
7. The method for controlling a wide-voltage double-active full-bridge DC-DC converter according to claim 6, wherein in said first step, according to an input voltage v of a primary full-bridge circuit 1 Output voltage v of secondary full-bridge circuit required currently 2 The calculated primary-secondary side voltage ratio is
Figure FDA0004285459930000047
8. The method of claim 6, wherein the voltage reference v2 of the secondary full-bridge circuit is set by an interface or by remote communication.
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