CN110212774B - Double-active-bridge DC-DC converter and backflow power optimization method thereof - Google Patents

Double-active-bridge DC-DC converter and backflow power optimization method thereof Download PDF

Info

Publication number
CN110212774B
CN110212774B CN201910500839.4A CN201910500839A CN110212774B CN 110212774 B CN110212774 B CN 110212774B CN 201910500839 A CN201910500839 A CN 201910500839A CN 110212774 B CN110212774 B CN 110212774B
Authority
CN
China
Prior art keywords
converter
power
bridge circuit
transmission power
phase full
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910500839.4A
Other languages
Chinese (zh)
Other versions
CN110212774A (en
Inventor
张宇
张天晖
陈庆
胡燕
关清心
袁栋
杨景刚
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Huazhong University of Science and Technology
State Grid Jiangsu Electric Power Co Ltd
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
Original Assignee
Huazhong University of Science and Technology
State Grid Jiangsu Electric Power Co Ltd
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huazhong University of Science and Technology, State Grid Jiangsu Electric Power Co Ltd, Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd filed Critical Huazhong University of Science and Technology
Priority to CN201910500839.4A priority Critical patent/CN110212774B/en
Publication of CN110212774A publication Critical patent/CN110212774A/en
Application granted granted Critical
Publication of CN110212774B publication Critical patent/CN110212774B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • 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
    • H02M3/33584—Bidirectional converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • 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
    • 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 invention discloses a double-active-bridge DC-DC converter and a backflow power optimization method thereof, wherein the backflow power optimization method comprises the following steps: acquiring the actual output voltage of the converter, and obtaining expected per unit transmission power according to the difference value between the acquired actual output voltage and the expected output voltage; obtaining an inner shift ratio and an outer shift ratio according to the expected per unit transmission power and the voltage conversion ratio of the converter; and controlling the switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit according to the internal shift ratio and the external shift ratio to realize zero-voltage switching-on or zero-current switching-off, and simultaneously enabling the backflow power of the converter to be minimum. According to the invention, by controlling the internal and external phase shift ratio of the double active bridges, on one hand, the output voltage within a wide load range is accurately controlled, and on the other hand, the reflux power of the converter is optimized, so that the reflux power of the converter is minimized while all fully-controlled switching devices are ensured to realize zero-voltage switching-on or zero-current switching-off, and the efficiency of the converter is improved.

Description

Double-active-bridge DC-DC converter and backflow power optimization method thereof
Technical Field
The invention belongs to the technical field of direct current-direct current converters, and particularly relates to a double-active-bridge DC-DC converter and a backflow power optimization method thereof.
Background
With the aggravation of global energy crisis and environmental pollution, distributed renewable energy sources, energy storage power stations, electric vehicles and the like are developed at a rapid pace, and popularization and development of direct-current power distribution networks are greatly promoted. The double-active-bridge DC-DC conversion device has the advantages of fast dynamic response, high power density, bidirectional power flow and the like, gradually becomes a core control unit of a DC power distribution network, and is also a key device for connecting DC loads such as electric automobiles and the like into the DC power distribution network. The performance of the double-active-bridge DC-DC conversion device influences the running performance of the whole direct current power distribution network, and the performance optimization technology for the double-active-bridge DC-DC converter becomes a hot point of domestic and foreign research, and has great engineering significance.
The backflow power is defined as the power output by the converter to the input side power supply, and the existence of the backflow power enables the converter to provide higher peak current under the same transmission power, so that the efficiency of the converter is greatly reduced, and therefore, certain necessity exists for the optimization analysis of the backflow power; the optimization analysis of the reflux power is to solve the minimum value of the reflux power according to the expression of the reflux power on the premise of certain transmission power. Conventional backflow power optimization analysis methods include lagrangian extremum methods, table lookup methods, and the like. Since the reflux power needs to consider a plurality of constraint conditions in the optimization process, the Lagrange extremum solving method cannot complete the solution under the constraint conditions; the table look-up method can deteriorate the real-time performance of the system and has no general applicability.
In summary, the conventional dual-active bridge DC-DC converter has the disadvantages of large backflow power and low transmission efficiency.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a double-active-bridge DC-DC converter and a backflow power optimization method thereof, and aims to solve the problem that the transmission efficiency is low due to large backflow power of the existing double-active-bridge DC-DC converter.
To achieve the above object, an aspect of the present invention provides a dual active bridge DC-DC converter, including: the device comprises a primary side single-phase full-bridge circuit, a transformer, a secondary side single-phase full-bridge circuit, a direct power control unit and a backflow power optimization control unit;
the direct current side of the primary single-phase full-bridge circuit is connected with a primary direct current power supply, and the alternating current side of the primary single-phase full-bridge circuit is connected with the primary side of the transformer through an auxiliary inductor; the alternating current side of the secondary single-phase full-bridge circuit is connected with the secondary side of the transformer, and the direct current side of the secondary single-phase full-bridge circuit is connected with a secondary direct current load;
the input end of the direct power control unit is connected with the direct current side of the secondary single-phase full bridge circuit, and the output end of the direct power control unit is connected with the input end of the reflux power optimization control unit; the output end of the backflow power optimization control unit is respectively connected with the control ends of the primary side single-phase full-bridge circuit and the secondary side single-phase full-bridge circuit;
the direct power control unit is used for acquiring the actual output voltage of the converter and obtaining expected transmission power according to the acquired actual output voltage and the expected output voltage;
the backflow power optimization control unit is used for controlling the switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit to realize zero-voltage switching-on or zero-current switching-off according to the expected transmission power and the voltage conversion ratio of the converter, and meanwhile, the backflow power of the converter is minimized;
wherein the converter has a voltage conversion ratio of k-V1/nV2N is the transformer transformation ratio, V1Is the input voltage V of the DC side of the primary single-phase full-bridge circuit2Is the output voltage of the DC side of the secondary single-phase full bridge circuit.
Further, the primary single-phase full bridge circuit includes: the first switch tube, the second switch tube, the third switch tube and the fourth switch tube, corresponding anti-parallel diodes and a primary side direct current voltage stabilizing capacitor form a first full-bridge circuit;
the first full-bridge circuit is connected in parallel with the primary side direct current voltage-stabilizing capacitor.
Further, the secondary side single-phase full-bridge circuit comprises: a fifth switching tube, a sixth switching tube, a seventh switching tube, an eighth switching tube, a corresponding anti-parallel diode and a secondary side direct current voltage stabilizing capacitor which form a second full-bridge circuit;
the second full-bridge circuit is connected with the secondary side direct-current voltage-stabilizing capacitor in parallel.
Further, according to the different magnitude relation of the inward shift ratio and the outward shift ratio, the converter has the following four working modes:
a first modality with a corresponding boundary constraint of d2＞d1，d1+d2The per unit transmission power range of the converter is more than or equal to 1
Figure BDA0002090166900000031
A second modality with a corresponding boundary constraint of d2＞d1，d1+d2Less than 1, the per unit transmission power range of the converter is that p is more than or equal to 0 and less than or equal to 1;
a third modality with a corresponding boundary constraint of d2≤d1，d1+d2< 1, the per unit transmission power range of the converter is
Figure BDA0002090166900000032
The fourth mode, corresponding to the boundary constraint of d2≤d1，d1+d2The per unit transmission power range of the converter is more than or equal to 1
Figure BDA0002090166900000033
Wherein d is1The ratio of the on-time difference of the driving signals of the first switching tube and the fourth switching tube in the primary side full-bridge circuit or the fifth switching tube and the eighth switching tube in the secondary side full-bridge circuit to the half switching period is defined as the internal shift ratio; d2Is an external shift comparison, is defined as the ratio of the on-time difference of the driving signals of the first switch tube in the primary side full-bridge circuit and the fifth switch tube in the secondary side full-bridge circuit to the half-switch period, and p is per unit transmission powerThe maximum transmission power of the converter is used as a reference value, and the actual transmission power is obtained through per unit.
The invention also provides a method for optimizing the backflow power of the double-active-bridge DC-DC converter, which comprises the following steps:
(1) acquiring the actual output voltage of the converter, and obtaining expected per unit transmission power according to the difference value between the acquired actual output voltage and the expected output voltage;
(2) obtaining an inner shift ratio and an outer shift ratio according to the expected per-unit transmission power and the voltage conversion ratio of the converter;
(3) and controlling the switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit to realize zero-voltage switching-on or zero-current switching-off according to the internal shift ratio and the external shift ratio, and simultaneously enabling the backflow power of the converter to be minimum.
Further, the obtaining of the inner shift ratio and the outer shift ratio according to the expected transmission power and the voltage conversion ratio of the converter in the step (2) specifically includes:
(2.1) acquiring per-unit transmission power of the converter under four modes according to the maximum transmission power of the converter;
(2.2) obtaining the direct-current power supply side backflow power of the converter according to the transformer transformation ratio, the input voltage of the direct-current side of the primary-side single-phase full-bridge circuit, the output voltage of the direct-current side of the secondary-side single-phase full-bridge circuit, the converter frequency, the auxiliary inductance value and the voltage conversion ratio of the converter;
(2.3) taking the maximum transmission power of the converter as a reference value of the reflux power at the DC power supply side to obtain per unit reflux power at the DC power supply side;
(2.4) under a single mode, optimizing per-unit return power of the DC power supply side according to a corresponding boundary constraint condition and per-unit transmission power under a mode corresponding to the converter, and obtaining an internal-external shift ratio which enables the per-unit return power to be minimum;
and (2.5) selecting the minimum per unit return power from the four modes to obtain an inside-outside shift ratio combination for realizing the minimum return power of the converter.
Further, the maximum transmission power of the converter is Pmax＝nV1V2/8fL；
Wherein n is the transformer transformation ratio V1Is the input voltage V of the DC side of the primary single-phase full-bridge circuit2The output voltage of the secondary single-phase full-bridge circuit on the direct current side is shown, f is the inverter frequency, and L is the auxiliary inductance value.
Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:
the method for optimizing the backflow power comprises the steps of firstly constructing a feasible domain in boundary constraint conditions corresponding to each submode of the converter, utilizing a method for solving the optimal condition in the feasible domain to realize local optimization control of the backflow power under a single submode, then selecting the optimal backflow power in four modes, and realizing global optimization control of the backflow power of the converter through switching among the modes, so that the backflow power of the converter is reduced to the minimum value while zero-voltage switching-on or zero-current switching-off of all fully-controlled switching devices is realized, and the transmission efficiency of the converter is improved.
Drawings
Fig. 1 is a schematic structural diagram of a dual active bridge DC-DC converter provided in an embodiment of the present invention;
fig. 2 is a circuit topology diagram of an implementation of a dual active bridge DC-DC converter according to an embodiment of the present invention;
fig. 3 is a structural diagram of a backflow power optimization control method for a dual-active bridge DC-DC converter according to an embodiment of the present invention;
fig. 4 is a two-dimensional per-unit transmission power distribution diagram of a dual-active bridge DC-DC converter according to an embodiment of the present invention in four modes;
fig. 5 to 8 are voltage and current waveforms of a dual active bridge DC-DC converter according to an embodiment of the present invention in four modes, respectively;
FIG. 9(a) shows the modal 1 operating region and the corresponding extreme d2minIn fig. 9(b), when the voltage conversion ratio k is 1.5 and p is 0.6, the return power is dependent on d2The variation curve of (d);
fig. 10(a) -10 (d) are respectively the optimized trajectories of the backflow power of the dual active bridge DC-DC converter under the mode 1, the mode 2, the mode 3 and the mode 4;
fig. 11(a) -11 (d) are curves of the change of the optimal return power with the per unit transmission power of the dual-active-bridge DC-DC converter in the mode 1, the mode 2, the mode 3, and the mode 4, respectively, when k is 1.5;
fig. 12 is a curve showing the change of the return power with the per unit transmission power of the dual-active-bridge DC-DC converter under the single-phase shift control and the return power optimization control of the present invention, respectively, when k is 1.5.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, an embodiment of the present invention provides a dual active bridge DC-DC converter, including: primary single-phase full-bridge circuit H1Transformer T, secondary single-phase full-bridge circuit H2The direct power control unit and the reflux power optimization control unit;
primary single-phase full-bridge circuit H1The direct current side of the transformer is connected with a primary side direct current power supply, and the alternating current side of the transformer is connected with the primary side of the transformer T through an auxiliary inductor L; secondary single-phase full-bridge circuit H2The alternating current side of the transformer T is connected with the secondary side of the transformer T, and the direct current side of the transformer T is connected with the direct current load of the secondary side; direct power control unit input end and secondary single-phase full-bridge circuit H2The output end of the DC side is connected with the input end of the reflux power optimization control unit; the output end of the reflux power optimization control unit is respectively connected with the primary single-phase full-bridge circuit H1And secondary single-phase full bridge circuit H2The control end of the controller is connected; the direct power control unit is used for acquiring the actual output voltage of the converter and obtaining expected transmission power according to the acquired actual output voltage and the expected output voltage; a reflux power optimization control unit for controlling the switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit to realize the control according to the expected transmission power and the voltage conversion ratio of the converterZero voltage turn-on or zero current turn-off while minimizing the power of the converter's return;
wherein, the voltage conversion ratio of the converter is represented by the formula k ═ V1/nV2Calculating, n is the transformer transformation ratio, V1Is the input voltage V of the DC side of the primary single-phase full-bridge circuit2Is the output voltage of the DC side of the secondary single-phase full bridge circuit.
Specifically, as shown in fig. 2, the primary side single-phase full bridge circuit H1The method comprises the following steps: primary side direct current voltage-stabilizing capacitor C1And a first switch tube Q forming a first full bridge circuit1A second switch tube Q2And a third switching tube Q3And a fourth switching tube Q4And a corresponding anti-parallel diode D1、D2、D3、D4(ii) a First full-bridge circuit and primary side direct current voltage-stabilizing capacitor C1Parallel connection; secondary single-phase full-bridge circuit H2The method comprises the following steps: secondary side DC voltage-stabilizing capacitor C2And a fifth switch tube Q forming a second full-bridge circuit5And a sixth switching tube Q6Seventh switch tube Q7The eighth switch tube Q8And a corresponding anti-parallel diode D5、D6、D7、D8(ii) a Second full-bridge circuit and secondary side DC voltage-stabilizing capacitor C2And (4) connecting in parallel.
The dual phase shift control of the present invention presents two phase shift ratios: d phase ratio of inward shift1Is defined as the ratio of the on-time difference of the driving signals of the first switch tube Q1 and the fourth switch tube Q4 in the primary side full bridge circuit or the fifth switch tube Q5 and the eighth switch tube Q8 in the secondary side full bridge circuit to the half switching period, and d is more than or equal to 01Less than or equal to 1; moving outward phase ratio d2Is defined as the ratio of the on-time difference of the driving signals of the first switch tube Q1 in the primary side full bridge circuit and the fifth switch tube Q5 in the secondary side full bridge circuit to the half switching period, and d is more than or equal to 02≤1。
According to the different size relation of the inward shift ratio and the outward shift ratio, the converter has the following four working modes:
when d is2＞d1，d1+d2The converter is in a mode 1 when the number of the converter is more than or equal to 1;
when d is2＞d1，d1+d2If the number is less than 1, the converter is in a mode 2;
when d is2≤d1，d1+d2If the number is less than 1, the converter is in a mode 3;
when d is2≤d1，d1+d2Not less than 1, the converter is in mode 4
Wherein d is1For an internal migration phase, d2The outward shift is compared.
The invention relates to a switching tube Q in a double-active-bridge DC-DC converter1～Q8In the above 4 working modes, the control signals of the upper and lower switching tubes of the same bridge arm are complementary, the control signals of the switching tubes have the same frequency and the duty ratio is 50%, so that the primary side inductive currents of the transformer flowing through each switching tube at the turn-on and turn-off moments have the same amplitude and opposite directions, and therefore, at the turn-on and turn-off moments, a current inevitably flows through the anti-parallel diode of the switching tube, and accordingly, the switching tubes inevitably realize zero-voltage turn-on or zero-current turn-off, namely, natural soft switching, so that only one hard switching loss occurs, the converter loss is reduced, and the converter efficiency is improved.
As shown in fig. 3, an embodiment of the present invention further provides a method for optimizing a backflow power of a dual active bridge DC-DC converter, including:
(1) collecting the actual output voltage V of the converter2(s) and based on the actual output voltage collected and the desired output voltage V2ref(s) obtaining an expected per unit transmission power p by the difference value;
(2) obtaining an internal shift ratio d according to the expected per unit transmission power p and the voltage conversion ratio k of the converter1Compared with d2；
(3) Controlling a switching tube Q in a primary single-phase full-bridge circuit and a secondary single-phase full-bridge circuit according to an internal shift ratio and an external shift ratio1～Q8Zero voltage turn-on or zero current turn-off is achieved while minimizing the power of the converter's return current.
Specifically, the phase ratio d of the inward shift is obtained1Compared with d2Is the reflux power optimization method of the inventionThe key to the process is described in detail below:
the step (2) comprises the following steps:
(2.1) acquiring per-unit transmission power of the converter under four modes according to the maximum transmission power of the converter;
when the phase ratio d is shifted inwards10, shift-out phase ratio d2At 0.5, the converter reaches a maximum transmission power Pmax＝nV1V2/8fL, wherein n is transformer transformation ratio V1Is the input voltage V of the DC side of the primary single-phase full-bridge circuit2The output voltage of the secondary single-phase full-bridge circuit on the direct current side is obtained, f is the frequency of the converter, and L is an auxiliary inductance value;
the per unit transmission power P can be obtained by using the maximum transmission power as a reference value of the actual transmission power P of the converter:
Figure BDA0002090166900000081
from equation (1), a two-dimensional graph of the power distribution of the converter in four modes can be obtained as shown in fig. 4, and it can be seen that the per-unit transmission power range of the converter under mode 1 and mode 3 is
Figure BDA0002090166900000082
The per unit transmission power range of the converter under the mode 2 is more than or equal to 0 and less than or equal to 1; per unit transmission power range of the down-converter in mode 4 is
Figure BDA0002090166900000083
(2.2) obtaining the backflow power of the direct-current power supply side of the converter in four modes according to the transformer transformation ratio, the input voltage of the direct-current side of the primary-side single-phase full-bridge circuit, the output voltage of the direct-current side of the secondary-side single-phase full-bridge circuit, the converter frequency, the auxiliary inductance value and the voltage conversion ratio of the converter;
with voltage conversion ratio k of the converter>1 is an example, the voltage and current waveforms of the converter in the above four modes are shown in sequence in fig. 5-8, wherein VABIs a primary side full bridge circuit H1Output voltage, V, at the midpoint of the bridge armCDIs a secondary side full bridge circuit H2Output voltage, V, at the midpoint of the bridge armLFor the auxiliary inductor voltage of the primary side of the transformer, iLAuxiliary inductive current for the primary side of the transformer;
referring to fig. 5, the backflow power in mode 1 is analyzed, when the circuit reaches a steady state, the inductive current in one switching period can be divided into eight stages, the average value of the inductive current is zero, the expression of the inductive current in each stage is analyzed, and the current symmetry i is used for analyzing the expression of the inductive current in each stageL(t0)＝-iL(t4)，iL(t1)＝-iL(t5)，iL(t2)＝-iL(t6)，iL(t3)＝-iL(t7) The following can be obtained:
Figure BDA0002090166900000091
according to the formula (2), iL(t0)、iL(t1)、iL(t2) Is always less than 0, and iL(t3) According to the phase ratio d of the internal shift1Comparison of moving outwards with d2The voltage conversion ratio k is different from the voltage conversion ratio k, and the positive and negative are uncertain;
when in use
Figure BDA0002090166900000092
iL(t3) If the current exceeds 0, the zero crossing point of the converter inductive current is t2～t3In between, set t2' is the zero crossing point, at t2～t2In stage I, the inductor current iLAnd a primary side full bridge circuit H1Output voltage V of bridge arm midpointABThe phase is opposite, the transmission power is negative, and the power supply side backflow power PcirComprises the following steps:
Figure BDA0002090166900000093
wherein T is a switching period;
when in use
Figure BDA0002090166900000094
iL(t3) If < 0, the zero crossing point of the converter is at t3～t4Are t'3To zero-crossing, t3～t′3In phase, the inductor current iLAnd a primary side full bridge circuit H1Output voltage V of bridge arm midpointABThe phase is opposite, the transmission power is negative, and the power supply side backflow power PcirComprises the following steps:
Figure BDA0002090166900000101
(2.3) acquiring per-unit return power of the converter under four modes according to the maximum transmission power of the converter;
at maximum transmission power P of the convertermax＝nV1V2The per unit return power M can be obtained by taking/8 fL as a reference valuecirComprises the following steps:
Figure BDA0002090166900000102
and obtaining a per unit reflow power expression under 4 modes of the converter by the same method:
Figure BDA0002090166900000103
(2.4) under a single mode, optimizing per-unit return power of the DC power supply side according to a corresponding boundary constraint condition and per-unit transmission power under a mode corresponding to the converter, and obtaining an internal-external shift ratio which enables the per-unit return power to be minimum;
the optimization of the reflux power is to solve the minimum value of the reflux power according to the expression of the reflux power on the premise that the transmission power is constant, and is described by taking the reflux power optimization under the mode 1 as an example, wherein the optimization objective function is formula (5), and the modal boundary constraint condition is as follows:
Figure BDA0002090166900000104
the expression p of per unit transmission power in mode 1 is 2 (1-d)2)(1+d2-2d1) In the formula (5), a new objective function is obtained, and the extreme value of the new objective function is obtained under the constraint condition, so that d is proper2＝d2minWhen the power is not the minimum value, the reflux power is the minimum value;
according to the phase ratio d of the internal shift1Comparison of moving outwards with d2A magnitude relation different from a voltage conversion ratio k, d2minThe expression is as follows:
Figure BDA0002090166900000111
as shown in fig. 9(a), the shaded area is the operation region corresponding to the mode 1, the mode 1 is divided into two regions according to the backflow power expression (5) in the mode 1, and d2min1 Corresponding operating region ①, d2min2Corresponding operating region ②, d2min1And d2min2The curves with p are shown as a dotted line and a solid line in the figure, respectively, and d can be seen2min1Not within the operational area.
When k is 1.5 and p is 0.6, the reflux power McirWith d2minThe change curve of (c) is shown in FIG. 9(b), and it can be seen that the reflux power McirAt d2minTaking a minimum value at the point when d2＜d2minWhen, with d2Increase of (2) the reflux power McirDecrease; when d is2≥d2minWhen, with d2Increase of (2) the reflux power McirAnd is increased. Therefore, at a given transmission power, if the back-flow power is at the extreme point d2minWhile in the operating region, select d2minAs an operating point for the backflow power minimization control; if the extreme point d of the reflux power2minNot in the operating region, d on the boundary closest to the extreme point in the operating region is selected2As an operating point for the backflow power minimization control.
(2.5) selecting the minimum per unit backflow power from the four modes to obtain an internal-external shift comparison combination for realizing the minimum backflow power of the converter;
the same can be analyzed for the other three modes, and fig. 10(a) -10 (d) show the operating regions of the four sub-modes, respectively, where the operating region is represented by (d)2P) and the return power optimization trajectory is shown by the arrow in the figure, wherein the expressions of the transmission power and the return power of the mode 4 only contain d1Therefore, the reflux power cannot be optimized.
FIG. 11(a) -FIG. 11(d) are sequential diagrams of the minimum reflow power M in four modescirAlong with the change curve of the per-unit transmission power p, when the per-unit transmission power p is 0-1/2, the converter can work under the modes 1, 2, 3 and 4; when the per-unit transmission power p is 1/2-2/3, the converter can work in modes 1, 2 and 3; the unimportant transmission power p only works under the mode 2 when being 2/3-1, and finally, local backflow power minimization control results of the four modes are compared to determine a globally optimal operation point track, wherein the globally optimal backflow power operation track is shown in fig. 12.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (5)

1. A dual active bridge DC-DC converter, comprising: the device comprises a primary side single-phase full-bridge circuit, a transformer T, a secondary side single-phase full-bridge circuit, a direct power control unit and a backflow power optimization control unit;
the direct current side of the primary side single-phase full-bridge circuit is connected with a direct current power supply, and the alternating current side of the primary side single-phase full-bridge circuit is connected with the primary side of the transformer T through an auxiliary inductor L; the alternating current side of the secondary single-phase full-bridge circuit is connected with the secondary side of the transformer T, and the direct current side of the secondary single-phase full-bridge circuit is connected with a secondary direct current load;
the input end of the direct power control unit is connected with the direct current side of the secondary single-phase full bridge circuit, and the output end of the direct power control unit is connected with the input end of the reflux power optimization control unit; the output end of the backflow power optimization control unit is respectively connected with the control ends of the primary side single-phase full-bridge circuit and the secondary side single-phase full-bridge circuit;
the direct power control unit is used for acquiring the actual output voltage of the converter and obtaining expected transmission power according to the acquired actual output voltage and the expected output voltage;
the backflow power optimization control unit is used for controlling the switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit to realize zero-voltage switching-on or zero-current switching-off according to the expected transmission power and the voltage conversion ratio of the converter, and meanwhile, the backflow power of the converter is minimized; the specific implementation method of the backflow power optimization control unit is that an inner shift ratio and an outer shift ratio are obtained according to the expected per unit transmission power and the voltage conversion ratio of the converter; controlling switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit to realize zero-voltage switching-on or zero-current switching-off according to the internal shift ratio and the external shift ratio, and simultaneously enabling the backflow power of the converter to be minimum; wherein, obtaining the inner shift ratio and the outer shift ratio according to the desired per-unit transmission power and the voltage conversion ratio of the converter specifically includes:
obtaining per-unit transmission power under four modes of the converter according to the expected transmission power of the converter and the maximum transmission power of the converter under the dual phase-shifting control; the four working modes of the converter comprise:
a first modality with a corresponding boundary constraint of d2>d1，d1+d2The per unit transmission power range of the converter is more than or equal to 1
Figure FDA0002508572230000021
Second modality, corresponding boundary constraintsIs d2>d1，d1+d2<1, the per unit transmission power range of the converter is that p is more than or equal to 0 and less than or equal to 1;
a third modality with a corresponding boundary constraint of d2≤d1，d1+d2<A per unit transmission power range of the converter is
Figure FDA0002508572230000022
The fourth mode, corresponding to the boundary constraint of d2≤d1，d1+d2The per unit transmission power range of the converter is more than or equal to 1
Figure FDA0002508572230000023
Wherein d is1For an internal migration phase, d2Comparing the power of the converter with the power of the converter, wherein p is per-unit transmission power, and the per-unit transmission power is obtained by taking the maximum transmission power of the converter as a reference value and per-unit the actual transmission power;
obtaining the reflux power of the DC power supply side of the converter according to the transformation ratio of the transformer, the input voltage of the DC side of the primary single-phase full-bridge circuit, the output voltage of the DC side of the secondary single-phase full-bridge circuit, the frequency of the converter, the auxiliary inductance value and the voltage conversion ratio of the converter;
taking the maximum transmission power of the converter under the dual phase-shifting control as a reference value of the reflux power at the DC power supply side to obtain per unit reflux power at the DC power supply side;
under a single mode, according to a corresponding boundary constraint condition and per-unit transmission power under a mode corresponding to the converter, per-unit backflow power of a DC power supply side is optimized, and an internal-external shift ratio which enables the per-unit backflow power to be minimum is obtained;
selecting the minimum per unit backflow power from the four modes to obtain an internal-external shift comparison combination for realizing the minimum backflow power of the converter;
wherein the converter has a voltage conversion ratio of k-V1/nV2N isTransformation ratio of transformer, V1Is the input voltage V of the DC side of the primary single-phase full-bridge circuit2Is the output voltage of the DC side of the secondary single-phase full bridge circuit.
2. The dual active bridge DC-DC converter of claim 1, wherein the primary single phase full bridge circuit comprises: the first switch tube, the second switch tube, the third switch tube and the fourth switch tube, corresponding anti-parallel diodes and a primary side direct current voltage stabilizing capacitor form a first full-bridge circuit;
the first full-bridge circuit is connected in parallel with the primary side direct current voltage-stabilizing capacitor.
3. The dual-active-bridge DC-DC converter according to claim 1, wherein the secondary-side single-phase full-bridge circuit comprises: a fifth switching tube, a sixth switching tube, a seventh switching tube, an eighth switching tube, a corresponding anti-parallel diode and a secondary side direct current voltage stabilizing capacitor which form a second full-bridge circuit;
the second full-bridge circuit is connected with the secondary side direct-current voltage-stabilizing capacitor in parallel.
4. A method for optimizing backflow power of a double-active-bridge DC-DC converter is characterized by comprising the following steps:
(1) acquiring the actual output voltage of the converter, and obtaining expected per unit transmission power according to the difference value between the acquired actual output voltage and the expected output voltage;
(2) obtaining an inner shift ratio and an outer shift ratio according to the expected per-unit transmission power and the voltage conversion ratio of the converter; specifically, the step (2) includes: obtaining per-unit transmission power under four modes of the converter according to the expected transmission power of the converter and the maximum transmission power of the converter under the dual phase-shifting control; the four working modes of the converter comprise:
a first modality with a corresponding boundary constraint of d2>d1，d1+d2The per unit transmission power range of the converter is more than or equal to 1
Figure FDA0002508572230000031
A second modality with a corresponding boundary constraint of d2>d1，d1+d2<1, the per unit transmission power range of the converter is that p is more than or equal to 0 and less than or equal to 1;
a third modality with a corresponding boundary constraint of d2≤d1，d1+d2<A per unit transmission power range of the converter is
Figure FDA0002508572230000032
The fourth mode, corresponding to the boundary constraint of d2≤d1，d1+d2The per unit transmission power range of the converter is more than or equal to 1
Figure FDA0002508572230000041
Wherein d is1For an internal migration phase, d2Comparing the power of the converter with the power of the converter, wherein p is per-unit transmission power, and the per-unit transmission power is obtained by taking the maximum transmission power of the converter as a reference value and per-unit the actual transmission power;
obtaining the reflux power of the DC power supply side of the converter according to the transformation ratio of the transformer, the input voltage of the DC side of the primary single-phase full-bridge circuit, the output voltage of the DC side of the secondary single-phase full-bridge circuit, the frequency of the converter, the auxiliary inductance value and the voltage conversion ratio of the converter;
taking the maximum transmission power of the converter under the dual phase-shifting control as a reference value of the reflux power at the DC power supply side to obtain per unit reflux power at the DC power supply side;
under a single mode, according to a corresponding boundary constraint condition and per-unit transmission power under a mode corresponding to the converter, per-unit backflow power of a DC power supply side is optimized, and an internal-external shift ratio which enables the per-unit backflow power to be minimum is obtained;
selecting the minimum per unit backflow power from the four modes to obtain an internal-external shift comparison combination for realizing the minimum backflow power of the converter;
(3) and controlling the switching tubes in the primary single-phase full-bridge circuit and the secondary single-phase full-bridge circuit to realize zero-voltage switching-on or zero-current switching-off according to the internal shift ratio and the external shift ratio, and simultaneously enabling the backflow power of the converter to be minimum.
5. The method as claimed in claim 4, wherein the maximum transmission power of the converter is Pmax＝nV1V2/8fL；
Wherein n is the transformer transformation ratio V1Is the input voltage V of the DC side of the primary single-phase full-bridge circuit2The output voltage of the secondary single-phase full-bridge circuit on the direct current side is shown, f is the inverter frequency, and L is the auxiliary inductance value.
CN201910500839.4A 2019-06-11 2019-06-11 Double-active-bridge DC-DC converter and backflow power optimization method thereof Active CN110212774B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910500839.4A CN110212774B (en) 2019-06-11 2019-06-11 Double-active-bridge DC-DC converter and backflow power optimization method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910500839.4A CN110212774B (en) 2019-06-11 2019-06-11 Double-active-bridge DC-DC converter and backflow power optimization method thereof

Publications (2)

Publication Number Publication Date
CN110212774A CN110212774A (en) 2019-09-06
CN110212774B true CN110212774B (en) 2020-08-14

Family

ID=67791914

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910500839.4A Active CN110212774B (en) 2019-06-11 2019-06-11 Double-active-bridge DC-DC converter and backflow power optimization method thereof

Country Status (1)

Country Link
CN (1) CN110212774B (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7190664B2 (en) * 2019-09-18 2022-12-16 パナソニックＩｐマネジメント株式会社 power converter
CN110572041B (en) * 2019-09-29 2021-10-22 西安理工大学 Bilateral PWM (pulse-Width modulation) plus phase shift control method of double-active full-bridge converter
CN110649819B (en) * 2019-10-16 2021-06-01 艾尚储能科技(苏州)有限公司 Closed-loop control method of double-active full-bridge direct-current converter based on DSP
CN111049392B (en) * 2019-12-27 2021-06-11 合肥工业大学 Double-active-bridge expanded phase-shifting minimum reflux power control method based on coordinate transformation
CN112260551B (en) * 2020-10-30 2021-08-24 西南交通大学 Control method and device of double-active-bridge DC-DC converter without direct current bias
CN112713781B (en) * 2021-01-11 2022-04-19 安徽工业大学 Optimization method for return power being zero under partial working mode of three-port converter
CN113014108A (en) * 2021-03-16 2021-06-22 株洲中车时代电气股份有限公司 Three-port bidirectional isolation converter and rail transit vehicle
CN113098252B (en) * 2021-04-02 2022-08-05 重庆邮电大学 Power electronic transformer soft start method based on energy feedback
CN113098285A (en) * 2021-04-16 2021-07-09 中国矿业大学 Method for optimally controlling reflux power of double-active-bridge converter under extended phase-shift control
CN113141119B (en) * 2021-04-19 2022-04-15 中国矿业大学 Method for optimally controlling backflow power and dynamic performance of dual-active-bridge converter
CN113968152B (en) * 2021-11-02 2022-09-27 合肥工业大学 Bidirectional wireless charging control method for electric automobile

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106849668B (en) * 2017-02-24 2019-10-15 南京南瑞集团公司 The double active bridge DC/DC converter novel bicyclic control methods of two-track phase control
CN107911028B (en) * 2017-12-22 2024-02-02 四川大学 DC-DC converter with buffer and method for reducing reflux power
CN108809103B (en) * 2018-06-05 2019-11-01 合肥工业大学 Cascade the minimum current stress control method of double active bridge DC-DC converters

Also Published As

Publication number Publication date
CN110212774A (en) 2019-09-06

Similar Documents

Publication Publication Date Title
CN110212774B (en) Double-active-bridge DC-DC converter and backflow power optimization method thereof
Dusmez et al. A fully integrated three-level isolated single-stage PFC converter
CN103269178B (en) Single-stage type isolated type three-phase two-way AC/DC converter and control method thereof
CN102594191A (en) Active clamping three-level zero-voltage soft-switching converter using coupled inductor
CN103560674A (en) Three-phase three-level LLC resonance direct current converter and control method of three-phase three-level LLC resonance direct current converter
CN100346562C (en) Transformer clamping zero voltage switch three level full bridge converter and its expansion circuit
CN112928919B (en) Isolated high-frequency resonant DC-DC converter with wide output voltage range and method
CN104935172A (en) Three-level soft switch forward-flyback DC/DC converter circuit topology structure
CN105119496A (en) Wide input range three-level LLC resonant converter and level switching control method
CN111224553A (en) Improved bidirectional half-bridge three-level LLC direct-current converter and synchronous control method thereof
Rafi et al. Optimal control of semi-dual active bridge DC/DC converter with wide voltage gain in a fast-charging station with battery energy storage
CN114301313A (en) Non-input energy storage inductance isolation resonance soft switching type three-phase PFC converter and control method thereof
CN111884521B (en) Single-stage Boost full-bridge Boost zero-current switch direct-current converter and control method thereof
CN114285286A (en) Single-stage zero-current switch full-bridge boost direct current converter and control method thereof
Narasimha et al. An improved closed loop hybrid phase shift controller for dual active bridge converter.
Chen et al. Power electronic transformer based on LLC resonant converter
CN203466729U (en) Multi-level LLC converter
CN113098285A (en) Method for optimally controlling reflux power of double-active-bridge converter under extended phase-shift control
CN112202351A (en) Single-stage isolated three-phase AC/DC rectifier of wide-range soft switch
CN106787756A (en) A kind of CL FT CL resonance DC converters
CN204810151U (en) Take parallelly connected modularization direct -current converter of input parallel outlet of soft switch
CN115765514A (en) Three-phase isolated converter capable of bidirectional conversion and control method thereof
CN111313708B (en) Full-bridge DC-DC converter
CN114006541A (en) Efficiency optimization control method of double-active half-bridge direct current converter
CN105656313A (en) Control method of three-phase direct current-direct current converter

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant