CN114430234B - Soft switch and current stress optimization method of DAB converter - Google Patents
Soft switch and current stress optimization method of DAB converter Download PDFInfo
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- CN114430234B CN114430234B CN202210055107.0A CN202210055107A CN114430234B CN 114430234 B CN114430234 B CN 114430234B CN 202210055107 A CN202210055107 A CN 202210055107A CN 114430234 B CN114430234 B CN 114430234B
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- 230000002457 bidirectional effect Effects 0.000 description 4
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33584—Bidirectional converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a soft switch and a current stress optimization method of a DAB converter, which are characterized in that the DAB converter works under the working condition that input and output voltages are not matched, all switching tubes of the converter work under the Zero Voltage Switching (ZVS) condition by controlling the relation between the phase shift ratio between bridges and the phase shift ratio between bridges, and the current stress is further optimized on the premise that all switching tubes of the converter work under the zero voltage switching condition, so that the conduction loss of the converter is reduced, and the overall efficiency of the system is improved. When the voltage transmission ratio of the DAB converter is changed within the range of 1-2, zero voltage switching-on of the switching tube within the full power range is realized, and when the voltage transmission ratio of the DAB converter is changed within the range of 0.5-1, the power range for realizing zero voltage switching-on of all the switching tubes is larger than that of single phase shift control, and the current stress is smaller.
Description
Technical Field
The invention belongs to the field of new energy application, and particularly relates to a soft switch of a double-active-bridge DCDC converter and a current stress optimization method, which comprise the fields of energy storage, electric vehicles, direct current micro-grids and the like, wherein the fields need to realize power bidirectional flow.
Background
Along with the proposal of a double-carbon strategic target of carbon neutralization, the rapid development of new energy technology is promoted. In the energy storage system, the energy storage system can effectively inhibit output fluctuation of renewable energy sources, and promote the consumption of the renewable energy sources. In the field of electric automobiles, with the increase of the storage amount of new energy electric cars, electric buses and electric trucks, related scholars put forward concepts of V2G, V2V and the like, and meanwhile, the more the user needs to realize the bidirectional flow of power for the electric automobiles. In the field of direct current micro-grids, high-power and high-efficiency direct current converters are needed to be connected with medium-voltage and low-voltage direct current buses so as to realize bidirectional flow of power. The DAB converter has the advantages of high power density, small volume, primary side and secondary side isolation, easy realization of bidirectional power flow and the like, and is widely applied to energy storage, electric automobiles and direct current micro-grid systems.
The conventional Single Phase Shift (SPS) control is widely used in the control of DAB converters due to its simple control scheme. However, when the input voltage and the output voltage are not matched, the SPS control can cause the defects that the current stress is increased, the ZVS operation power range is reduced, the switching tube is hard-opened during light load, and the like. Therefore, the DAB converter operates less efficiently in an input-output voltage mismatch operating scenario. The SPS control has only one control degree of freedom, and has great limitation in optimizing control, so that the related scholars propose control modes with high degrees of freedom such as Extended Phase Shift (EPS), double Phase Shift (DPS), triple Phase Shift (TPS) control and the like to optimize the efficiency of the system. There are mainly two ways in improving the efficiency of the system: the first method is mainly to optimize the current stress of the system and reduce the conduction loss of the system; the second is mainly to realize ZVS reduction of switching loss of the switching tube.
However, the existing DAB converter has certain defects and shortcomings in overall efficiency optimization, and is mainly concentrated on:
1. in the first class of optimization schemes of the DAB converter system, only the conduction loss of the system is optimized, but for the high-frequency DAB converter, the loss mainly comes from the switching loss, so the high-frequency DAB converter system should mainly come from the switching loss of the system.
2. In the second class of DAB converter system optimization schemes, all switching tubes ZVS are realized as optimization targets, but the following problems exist in the prior literature: the soft switching optimization problem in literature multi-analysis buck mode, while boost mode also exists for the operating conditions of the converter; the power range for realizing soft switching is smaller; ZVS of all switching tubes of the DAB converter is achieved but the system current stress is increased.
Disclosure of Invention
The invention provides a soft switch of a DAB converter and a current stress optimization method, which aims to overcome the defects in the prior art, so as to expand the soft switch power range of the DAB converter, reduce the current stress of a system and improve the overall operation efficiency of the converter.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
the soft switch of the DAB converter and the current stress optimization method are characterized by comprising the following steps:
step 1: when the DAB converter works under the working condition that the input voltage and the output voltage are not matched, obtaining zero-voltage turn-on constraint inductor current per unit value corresponding to the EPS control mode and the SPS control mode by utilizing the formula (1);
in the formula (1), i L (t 0 ) At t 0 Inductor current value i when switching tube in DAB converter operates L (t 1 ) At t 1 Inductor current value i when switching tube in DAB converter operates L (t 2 ) At t 2 Inductance current value at the time of operation of a switching tube in the DAB converter, k represents voltage transmission ratio, and k=v i /(nV o )，V i V being the input voltage of DAB converter o The output voltage of the DAB converter is n, which is the transformation ratio of the high-frequency transformer; d (D) 1 For intra-bridge movement comparison D 2 EPSL for inter-bridge phase shift ratio 1 For intra-bridge displacement of D 1 On the inverter bridge side, and the inter-bridge phase shift ratio D 2 Greater than intra-bridge phase D 1 Phase shift control mode of EPSL 2 For intra-bridge displacement of D 1 On the inverter bridge side, and the inter-bridge phase shift ratio D 2 Less than intra-bridge phase D 1 In the phase shift control mode of (2), EPSR is intra-bridge phase shift D 1 A phase shift control mode at the rectifier bridge side, wherein SPS is a single phase shift control mode; from EPSL 1 、EPSL 2 And EPSR constitute an extended phase shift control mode, denoted EPS;
step 2: obtaining a transmission power per unit value p in an EPS control mode and an SPS control mode by using the formula (2);
in the formula (2), P is the transmission power of the DAB converter, P N EPSL for the rated transmission power of the DAB converter 1 The constraint condition of the control mode is that D is more than or equal to 0 1 ≤D 2 ≤1，EPSL 2 The constraint condition of the control mode is that D is more than or equal to 0 2 ≤D 1 The constraint condition of the EPSR control mode is not less than 1 and not more than 0 and not more than D 1 +D 2 The constraint condition of SPS control mode is 0-D 2 ≤1；
Step 3: obtaining a transmission power range in a soft switching area corresponding to each phase shift mode of an EPS control mode and an SPS control mode under two working conditions of downward boosting and downward reducing of the DAB converter by utilizing a formula (3);
in the formula (3), k >1 represents a step-down operation condition, and k < 1 represents a step-up operation condition;
step 4: when the input/output voltage of the DAB converter is in the step-down working condition, if the DAB converter is in heavy-load operation, the EPSL is selected 1 As a phase shift control method, if the DAB converter is operated under light load, EPSL is selected 2 As a phase shift control mode;
when the input and output voltage of the DAB converter is in a boosting working condition, selecting an EPSR as a phase-shifting control mode;
step 5: obtaining a current stress per unit value of the DAB converter in a corresponding mode by using the formula (4);
in the formula (4), i P-EPSL1 For EPSL 1 Current stress per unit value, i of DAB converter in control mode P-EPSL2 For EPSL 2 Current stress per unit value, i of DAB converter in control mode P-EPSR Is the current stress per unit value, i of the DAB converter in EPSR control mode P-SPS The current stress per unit value of the DAB converter in the SPS control mode is obtained;
step 6: establishing a mathematical model of the minimum current stress under the constraint condition of the soft switch by using the formula (5), and solving by adopting a Ka Lu Shen Country method, so that the combination of phase shift is searched in a soft switch area to minimize the current stress;
in the formula (5), L (D) 1 ,D 2 Lambda, mu) is a Lagrangian function; where λ represents an equality constraint coefficient, μ represents an inequality constraint coefficient, f (D 1 ,D 2 ) Is an objective function, namely, is current stress; h is a j (D 1 ,D 2 ) Lambda is the j-th equality constraint j Is the corresponding j constraint coefficient, m represents the equality constraint number of the DAB converter, g l (D 1 ,D 2 ) For the first inequality constraint, mu l For the corresponding first constraint coefficient, l represents the inequality constraint number of the DAB converter;
under the condition of voltage reduction, if the DAB converter is in heavy-load operation, obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimum by utilizing a formula (6);
the phase shift ratio relation and the phase shift ratio value at which the current stress is minimized are obtained by using the formula (7), but at this time, the solution is a soft switch boundary constraint condition,
under the condition of voltage reduction, if the DAB converter runs under light load, obtaining an optimized path of current stress of the DAB converter by using a formula (7) when all switching tubes work under a zero-voltage on condition;
in the formula (7), A is a proportional coefficient of intra-bridge phase shift and inter-bridge phase shift, B is a superposition coefficient of intra-bridge phase shift and inter-bridge phase shift, and w is a soft switching adjustment coefficient;
under the ascending operation condition, obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimized by utilizing the formula (8);
step 7: and (3) selecting different phase shift ratio combinations to carry out closed loop control on the DAB converter according to different working conditions of the DAB converter working under input and output voltage and the running condition of the DAB converter by utilizing the control conclusion obtained in the step (6), so that all switching tubes of the DAB converter work under zero-voltage on condition to realize optimization of current stress of the DAB converter.
Compared with the prior art, the invention has the beneficial effects that:
1. when the input and output voltage of the DAB converter is in a step-down working condition, the invention combines EPSL by restricting the inductance current condition 1 Control mode and EPSL 2 The control mode has the control advantage of realizing zero voltage switching on of all switching tubes, realizes zero voltage switching on of the switching tubes in a full power range when the voltage transmission ratio of the DAB converter is changed in a range of 1-2, optimizes current stress in a power region where the DAB converter realizes zero voltage switching on, and can reduce the current stress of the DAB converter compared with the traditional single phase shift control (SPS);
2. when the input and output voltage of the DAB converter is in a boosting working condition, the invention adopts an EPSR control mode to expand the zero-voltage switching-on power range of the DAB converter when the voltage transmission ratio of the DAB converter is changed within the range of 0.5-1, realizes the zero-voltage switching-on of all switching tubes of the DAB converter within the power range, optimizes the current stress in the power area of the DAB converter for realizing the zero-voltage switching-on, and can reduce the current stress of the DAB converter compared with the traditional single phase shift control.
Drawings
Fig. 1 is a topology of a DAB converter in an embodiment of the invention;
FIG. 2 is a theoretical waveform diagram of voltage and current of the DAB converter under EPS control and SPS control;
FIG. 3a is a waveform diagram of transmission power of the DAB converter in soft-switching constraint region under EPS control and SPS control when the voltage transmission ratio k >1 of the present invention;
FIG. 3b is a graph of transmission power waveforms of the DAB converter in soft-switching constraint areas under EPS control and SPS control when the voltage transmission ratio k >1 of the present invention;
FIG. 4a is a graph of current stress optimization versus the buck operating environment of the DAB converter of the present invention;
FIG. 4b is a graph of current stress optimization versus the DAB converter of the present invention in a boost operating environment;
fig. 5a is an experimental waveform diagram of the DAB converter in the case of k=1.75, p=400W according to the present invention;
fig. 5b is an experimental waveform diagram of the DAB converter in the present invention when k=1.75, p=3000W;
fig. 5c is an experimental waveform diagram of the DAB converter in the case of k=0.75, p=950W according to the present invention;
FIG. 6 is a graph of the drive waveform and junction capacitance voltage waveforms for a switching tube of the present invention with zero voltage on;
FIG. 7 is a graph comparing system efficiency under the proposed optimization strategy with the conventional SPS control strategy.
Detailed Description
In this embodiment, a dual active bridge DC-DC converter topology is shown in fig. 1. Input voltage of V i The output voltage is V o The method comprises the steps of carrying out a first treatment on the surface of the Primary side inversion full-bridge switch tube S 1 ～S 4 The structure is that the output alternating voltage value is V ab The method comprises the steps of carrying out a first treatment on the surface of the Secondary side rectifying full-bridge switch tube S 5 ～S 8 The input AC voltage value is V cd The method comprises the steps of carrying out a first treatment on the surface of the The primary and secondary full bridges are connected through a high-frequency transformer, and the transformation ratio is n 1; l is the sum of leakage inductance and auxiliary inductance of the transformer, and the flowing inductance current is i L ；C i Supporting a capacitance for the input side; c (C) o A filter capacitor for the output side; the load is R. For simplicity of analysis, it is assumed that the system is in a steady state operation, i.e., constant input and output voltages. Let voltage transmission ratio k=v i /(nV o ) In the present embodiment, the voltage transmission ratio k is considered to vary in the range of 0.5 to 2, when k<1 is a boost mode, k>The step-down mode is at 1. Without losing generality, the method only takes power forward flow as an example, and power reverse flow can be analogized.
Based on the DAB converter topology structure, the soft switch and the current stress optimization method of the double-active bridge DCDC converter control the relationship between the inter-bridge phase shift ratio and the intra-bridge phase shift ratio, so that all switching tubes of the converter work under the condition of zero voltage on (ZVS) to reduce the switching loss of the system, and further optimize the current stress of the system on the premise that all switching tubes of the converter work under the condition of ZVS, so that the conduction loss of the converter is reduced and the overall efficiency of the system is improved, and the optimization control method is specifically implemented in the following manner:
step 1: when the DAB converter works under the working condition that the input voltage and the output voltage are not matched, the zero voltage on-constraint inductor current per unit value corresponding to the EPS control mode and the SPS control mode is obtained by utilizing the formula (1);
in the formula (1), i L (t 0 ) At t 0 Inductor current value i when switching tube in DAB converter operates L (t 1 ) At t 1 Inductor current value i when switching tube in DAB converter operates L (t 2 ) At t 2 Inductor current value k represents voltage transmission when switching transistor in DAB converter operates at timeRatio, and k=v i /(nV o )，V i V being the input voltage of DAB converter o The output voltage of the DAB converter is n, which is the transformation ratio of the high-frequency transformer; d (D) 1 For intra-bridge movement comparison D 2 EPSL for inter-bridge phase shift ratio 1 For intra-bridge displacement of D 1 On the inverter bridge side, and the inter-bridge phase shift ratio D 2 Greater than intra-bridge phase D 1 Phase shift control mode of EPSL 2 For intra-bridge displacement of D 1 On the inverter bridge side, and the inter-bridge phase shift ratio D 2 Less than intra-bridge phase D 1 In the phase shift control mode of (2), EPSR is intra-bridge phase shift D 1 A phase shift control mode at the rectifier bridge side, wherein SPS is a single phase shift control mode; from EPSL 1 、EPSL 2 And EPSR constitute an extended phase shift control mode, denoted EPS; as shown in fig. 2, the inductance voltage and current waveforms of each mode in the EPS control mode and the SPS control mode are shown;
step 2: obtaining a transmission power per unit value p in an EPS control mode and an SPS control mode by using the formula (2);
in the formula (2), P is the transmission power of the DAB converter, P N EPSL for rated transmission power of DAB converter 1 The constraint condition of the control mode is that D is more than or equal to 0 1 ≤D 2 ≤1，EPSL 2 The constraint condition of the control mode is that D is more than or equal to 0 2 ≤D 1 The constraint condition of the EPSR control mode is not less than 1 and not more than 0 and not more than D 1 +D 2 The constraint condition of SPS control mode is 0-D 2 ≤1；
Step 3: obtaining a transmission power range in a soft switching area corresponding to each phase shift mode of an EPS control mode and an SPS control mode under two working conditions of boosting and reducing of the DAB converter by using a formula (3), and drawing transmission power diagrams of each operation mode of the EPS control mode and the SPS control mode under the soft switching constraint conditions of the boosting working condition and the reducing working condition, as shown in fig. 3a and 3 b;
in the formula (3), k >1 represents a step-down operation condition, and k < 1 represents a step-up operation condition;
step 4: selecting different phase-shifting control modes according to different operation conditions of the DAB converter, and taking a soft switching power range as a mode selection standard according to the transmission power range obtained in the step 3; when the input/output voltage of the DAB converter is in the step-down working condition, if the DAB converter is in heavy-load operation, the EPSL is selected 1 As a phase shift control method, if the DAB converter is operated under light load, EPSL is selected 2 As a phase shift control mode;
when the input and output voltage of the DAB converter is in a boosting working condition, selecting an EPSR as a phase-shifting control mode;
step 5: obtaining a current stress per unit value of the DAB converter in a corresponding mode by using the formula (4);
in the formula (4), i P-EPSL1 For EPSL 1 Current stress per unit value, i of DAB converter in control mode P-EPSL2 For EPSL 2 Current stress per unit value, i of DAB converter in control mode P-EPSR Is the current stress per unit value, i of the DAB converter in EPSR control mode P-SPS The current stress per unit value of the DAB converter in the SPS control mode is obtained;
step 6: establishing a mathematical model of the minimum current stress under the constraint condition of the soft switch by using the formula (5), and solving by adopting a Ka Lu Shen Country method, so that the combination of phase shift is searched in a soft switch area to minimize the current stress;
in the formula (5), L (D) 1 ,D 2 Lambda, mu) is LagrangianA day function; where λ represents an equality constraint coefficient, μ represents an inequality constraint coefficient, f (D 1 ,D 2 ) Is an objective function, namely, is current stress; h is a j (D 1 ,D 2 ) Lambda is the j-th equality constraint j Is the corresponding j constraint coefficient, m represents the equality constraint number of the DAB converter, g l (D 1 ,D 2 ) For the first inequality constraint, mu l For the corresponding first constraint coefficient, l represents the inequality constraint number of the DAB converter;
under the condition of voltage reduction, if the DAB converter is in heavy-load operation, obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimum by utilizing a formula (6);
obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimized by using the formula (7), wherein the solution is a soft switch boundary constraint condition;
under the condition of voltage reduction, if the DAB converter runs under light load, obtaining an optimized path of current stress of the DAB converter by using a formula (7) when all switching tubes work under the condition of zero voltage opening;
in the formula (7), A is a proportional coefficient of intra-bridge phase shift and inter-bridge phase shift, B is a superposition coefficient of intra-bridge phase shift and inter-bridge phase shift, and w is a soft switching adjustment coefficient;
under the ascending operation condition, obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimized by utilizing the formula (8);
substituting the obtained current stress optimization solution formula (6), formula (7) and formula (8) into formula (4) under the soft switching condition to obtain the current stress values of the system under the EPS control mode and the SPS control mode;
in the formula (9), Q i (k, p) is a current stress ratio, the value of which is equal to the ratio of the current stress value of the DAB converter after optimization in the corresponding power range to the current stress value of the DAB converter under the control of the traditional SPS mode, and as can be seen from fig. 4a and fig. 4b, the current stress of the DAB converter is optimized to a certain extent under both the operation conditions of boosting and reducing in the optimized power range;
step 7: and (3) selecting different phase shift ratio combinations to carry out closed loop control on the DAB converter according to different working conditions of the DAB converter working under the input and output voltage and the running condition of the DAB converter by utilizing the control conclusion obtained in the step (6), so that all switching tubes of the DAB converter work under the zero-voltage on condition to realize optimization of the current stress of the DAB converter.
In order to further verify the feasibility of the optimization scheme, a physical verification platform is built by taking TMS320F28335 as a main control chip, and platform parameters are shown in table 1:
TABLE 1DAB converter experimental parameters
Fig. 5a shows voltage waveforms and current waveforms output from two side legs of the inductor when the voltage transmission ratio k=1.75 and the transmission power p=400W, and the DAB converter adopts EPSL 2 As a phase shift control mode, all switching tubes meet soft switching conditions when in operation. Fig. 5b shows the output voltage waveform and current waveform of the two side arms of the inductor when the voltage transmission ratio k=1.75 and the transmission power p=3000W, and the controller adopts EPSL 1 As a phase shift control mode, all switching tubes meet the requirement of soft switching. Thus, when the voltage transmission ratio k>1, the optimization control algorithm provided by the method can realize the whole processThe zero voltage of all switching tubes in the power range is on. As shown in fig. 5c, the voltage-current waveforms at both ends of the inductor are shown when the voltage transmission ratio k=0.75 in the boost mode, and the DBA converter transmits power p=950W corresponding to the power per unit value p=0.4 of the DBA converter, and the DBA converter adopts EPSL in the transmission power 1 Phase shift control mode, EPSL 2 The phase shift control mode and the SPS phase shift control mode cannot realize zero voltage turn-on of all switching tubes. When the DBA converter adopts EPSR as the phase shift control mode, the transmission power is in the soft switching power range, and as can be seen from fig. 5c, all switching tubes of the DBA converter meet the soft switching inductor current constraint condition. Thus, when the voltage transmission ratio k<And 1, the soft switching power range of the DBA converter can be expanded by adopting an EPSR phase-shift control mode.
Fig. 6 shows a lower arm switching tube S of the DBA converter 2 、S 3 、S 6 、S 7 Is set to drive waveform V GS Sum junction capacitance voltage V DS The waveform can be seen from the graph that when the driving signal comes, the inductor current reversely charges the capacitor voltage of the switch tube junction to be reduced to 0V before the switch tube is conducted, so that the switch tube is turned on with zero voltage when being conducted, and the symmetry can know that four tubes of the upper bridge arm are turned on with zero voltage.
FIG. 7 is a graph comparing the DAB converter efficiency curve obtained in SPS phase shift control mode with the DAB converter efficiency curve obtained by the optimization strategy provided by the method. It can be seen that the DAB converter efficiency under SPS phase shift control is only 82.5% when p=200w is transmitted at low power, whereas the DAB converter efficiency obtained by the strategy of the method is 91.2%; the efficiency of the DAB converter in the two control modes is 92.4% and 95.8% respectively during high power operation. The DAB converter switching tube under SPS phase shift control can not work under the zero voltage on condition in low power transmission, and the larger current stress leads to larger conduction loss. With the increase of transmission power, DAB converter switching tubes under SPS phase shift control are all operated under the zero-voltage on condition, the DAB converter efficiency is improved, but the current stress at the moment is still larger than the current stress obtained under the strategy provided by the method, the corresponding conduction loss is large, and the efficiency is still lower. Therefore, the optimization strategy provided by the method can ensure that all switching tubes of the DAB converter work under the zero-voltage on condition, effectively reduce the current stress of the DAB converter, reduce the switching loss and the conduction loss, and improve the efficiency of the DAB converter.
Claims (1)
1. A soft switch of DAB converter and a current stress optimization method are characterized in that the method is carried out according to the following steps:
step 1: when the DAB converter works under the working condition that the input voltage and the output voltage are not matched, obtaining zero-voltage turn-on constraint inductor current per unit value corresponding to the EPS control mode and the SPS control mode by utilizing the formula (1);
in the formula (1), i L (t 0 ) At t 0 Inductor current value i when switching tube in DAB converter operates L (t 1 ) At t 1 Inductor current value i when switching tube in DAB converter operates L (t 2 ) At t 2 Inductance current value at the time of operation of a switching tube in the DAB converter, k represents voltage transmission ratio, and k=v i /(nV o )，V i V being the input voltage of DAB converter o The output voltage of the DAB converter is n, which is the transformation ratio of the high-frequency transformer; d (D) 1 For intra-bridge movement comparison D 2 EPSL for inter-bridge phase shift ratio 1 For intra-bridge displacement of D 1 On the inverter bridge side, and the inter-bridge phase shift ratio D 2 Greater than intra-bridge phase D 1 Phase shift control mode of EPSL 2 For intra-bridge displacement of D 1 On the inverter bridge side, and the inter-bridge phase shift ratio D 2 Less than intra-bridge phase D 1 In the phase shift control mode of (2), EPSR is intra-bridge phase shift D 1 Phase shift on the rectifier bridge sideA control mode, SPS is a single phase shift control mode; from EPSL 1 、EPSL 2 And EPSR constitute an extended phase shift control mode, denoted EPS;
step 2: obtaining a transmission power per unit value p in an EPS control mode and an SPS control mode by using the formula (2);
in the formula (2), P is the transmission power of the DAB converter, P N EPSL for the rated transmission power of the DAB converter 1 The constraint condition of the control mode is that D is more than or equal to 0 1 ≤D 2 ≤1，EPSL 2 The constraint condition of the control mode is that D is more than or equal to 0 2 ≤D 1 The constraint condition of the EPSR control mode is not less than 1 and not more than 0 and not more than D 1 +D 2 The constraint condition of SPS control mode is 0-D 2 ≤1；
Step 3: obtaining a transmission power range in a soft switching area corresponding to each phase shift mode of an EPS control mode and an SPS control mode under two working conditions of downward boosting and downward reducing of the DAB converter by utilizing a formula (3);
in the formula (3), k >1 represents a step-down operation condition, and k < 1 represents a step-up operation condition;
step 4: when the input/output voltage of the DAB converter is in the step-down working condition, if the DAB converter is in heavy-load operation, the EPSL is selected 1 As a phase shift control method, if the DAB converter is operated under light load, EPSL is selected 2 As a phase shift control mode;
when the input and output voltage of the DAB converter is in a boosting working condition, selecting an EPSR as a phase-shifting control mode;
step 5: obtaining a current stress per unit value of the DAB converter in a corresponding mode by using the formula (4);
in the formula (4), i P-EPSL1 For EPSL 1 Current stress per unit value, i of DAB converter in control mode P-EPSL2 For EPSL 2 Current stress per unit value, i of DAB converter in control mode P-EPSR Is the current stress per unit value, i of the DAB converter in EPSR control mode P-SPS The current stress per unit value of the DAB converter in the SPS control mode is obtained;
step 6: establishing a mathematical model of the minimum current stress under the constraint condition of the soft switch by using the formula (5), and solving by adopting a Ka Lu Shen Country method, so that the combination of phase shift is searched in a soft switch area to minimize the current stress;
in the formula (5), L (D) 1 ,D 2 Lambda, mu) is a Lagrangian function; where λ represents an equality constraint coefficient, μ represents an inequality constraint coefficient, f (D 1 ,D 2 ) Is an objective function, namely, is current stress; h is a j (D 1 ,D 2 ) Lambda is the j-th equality constraint j Is the corresponding j constraint coefficient, m represents the equality constraint number of the DAB converter, g l (D 1 ,D 2 ) For the first inequality constraint, mu l For the corresponding first constraint coefficient, l represents the inequality constraint number of the DAB converter;
under the condition of voltage reduction, if the DAB converter is in heavy-load operation, obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimum by utilizing a formula (6);
the phase shift ratio relation and the phase shift ratio value at which the current stress is minimized are obtained by using the formula (7), but at this time, the solution is a soft switch boundary constraint condition,
under the condition of voltage reduction, if the DAB converter runs under light load, obtaining an optimized path of current stress of the DAB converter by using a formula (7) when all switching tubes work under a zero-voltage on condition;
in the formula (7), A is a proportional coefficient of intra-bridge phase shift and inter-bridge phase shift, B is a superposition coefficient of intra-bridge phase shift and inter-bridge phase shift, and w is a soft switching adjustment coefficient;
under the ascending operation condition, obtaining a phase shift ratio relation and a phase shift ratio value when the current stress is minimized by utilizing the formula (8);
step 7: and (3) selecting different phase shift ratio combinations to carry out closed loop control on the DAB converter according to different working conditions of the DAB converter working under input and output voltage and the running condition of the DAB converter by utilizing the control conclusion obtained in the step (6), so that all switching tubes of the DAB converter work under zero-voltage on condition to realize optimization of current stress of the DAB converter.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110401350A (en) * | 2019-07-01 | 2019-11-01 | 中南大学 | The phase-shifting control method of the full-load range ZVS of double active full-bridge bidirectional DC-DC converters |
| US10673343B1 (en) * | 2019-01-31 | 2020-06-02 | Shanhai Jiao Tong University | Diode clamp mixed three-level dual active full-bridge converter and control method thereof |
| CN113258785A (en) * | 2021-06-10 | 2021-08-13 | 中国矿业大学 | Multi-objective optimization control method for full power range of double-active-bridge converter |
| CN113904560A (en) * | 2021-10-13 | 2022-01-07 | 湖南工业大学 | DAB converter multi-target unified control method based on triple phase-shift control |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10673343B1 (en) * | 2019-01-31 | 2020-06-02 | Shanhai Jiao Tong University | Diode clamp mixed three-level dual active full-bridge converter and control method thereof |
| CN110401350A (en) * | 2019-07-01 | 2019-11-01 | 中南大学 | The phase-shifting control method of the full-load range ZVS of double active full-bridge bidirectional DC-DC converters |
| CN113258785A (en) * | 2021-06-10 | 2021-08-13 | 中国矿业大学 | Multi-objective optimization control method for full power range of double-active-bridge converter |
| CN113904560A (en) * | 2021-10-13 | 2022-01-07 | 湖南工业大学 | DAB converter multi-target unified control method based on triple phase-shift control |
Non-Patent Citations (1)
| Title |
|---|
| 黄珺 ; 王跃 ; 李卓强 ; 雷万钧 ; .基于三重移相控制的双主动全桥直流变换器优化调制策略.中国电机工程学报.2016,(第06期),全文. * |
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