CN116317595A - Four-degree-of-freedom efficiency optimization control method suitable for bidirectional direct current converter of electric locomotive - Google Patents

Four-degree-of-freedom efficiency optimization control method suitable for bidirectional direct current converter of electric locomotive Download PDF

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CN116317595A
CN116317595A CN202310155514.3A CN202310155514A CN116317595A CN 116317595 A CN116317595 A CN 116317595A CN 202310155514 A CN202310155514 A CN 202310155514A CN 116317595 A CN116317595 A CN 116317595A
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phase shift
shift angle
internal phase
converter
freedom
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王德顺
王开毅
庄俊
曹远志
薛金花
戴正洲
李晓亮
宋文胜
邓亚茹
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China Online Shanghai Energy Internet Research Institute Co ltd
Southwest Jiaotong University
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China Online Shanghai Energy Internet Research Institute Co ltd
Southwest Jiaotong University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0012—Control circuits using digital or numerical techniques
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices

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  • Power Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The invention relates to a four-degree-of-freedom efficiency optimization control method suitable for a bidirectional direct current converter of an electric locomotive, which comprises the following steps: based on an inductance current model of the converter under triple phase shift control and a soft switch constraint condition, calculating to obtain an external phase shift quantity meeting all the soft switches of the switching tube; obtaining the relation between a primary side internal phase shift angle and a secondary side internal phase shift angle which enable the reflux power to be zero under the constraint condition of a full soft switch according to the reflux power expression of the converter; combining Lagrangian function and power expression of the double active full-bridge DC-DC converter under three-degree-of-freedom control, introducing switching frequency as a fourth degree of control freedom, solving the expressions of external phase shift quantity, primary side internal phase shift angle, secondary side internal phase shift angle and switching frequency which meet minimum current stress optimization on the basis of meeting all soft switching and zero return power constraint conditions, and optimally controlling the converter by the obtained solution. The invention can realize the steady-state performance comprehensive optimization of the bidirectional full-bridge DC-DC converter.

Description

Four-degree-of-freedom efficiency optimization control method suitable for bidirectional direct current converter of electric locomotive
Technical Field
The invention relates to the technical field of power electronic converters, in particular to a four-degree-of-freedom efficiency optimization control method suitable for a bidirectional direct current converter of an electric locomotive.
Background
At present, the gravity center of the energy structure in China is gradually shifted from the traditional fossil energy to the clean energy, and renewable energy is gradually becoming the mainstream. The bidirectional full-bridge DC-DC converter has the advantages of simple structure, bidirectional energy flow, high power density and the like, and is widely applied to the fields of distributed power generation systems, storage battery energy storage systems, electric locomotives, electric automobile charging, energy feedback and the like.
The bidirectional full-bridge DC-DC converter generally adopts a phase shift control method, is simple to realize and is easy to realize bidirectional energy transmission, but can generate larger reflux power and current stress under the working condition of unmatched input and output voltages or light load, so that the efficiency of the converter is reduced. In addition, an increase in switching frequency results in an increase in switching losses, which in turn reduces converter efficiency.
In order to improve the efficiency of the converter, a number of optimization methods of reflow power optimization, minimum current stress optimization or soft switching range expansion are proposed successively. Although the working efficiency of the converter can be improved by the method, the efficiency optimization can be realized only through the limitation of the control freedom degree, the reflux power optimization, the current stress optimization or the soft switching range expansion, and all influence factors can not be considered, so that the steady-state performance optimization effect of the converter is not obvious, and the comprehensive efficiency improvement can not be realized. In addition, most of the traditional optimization methods adopt constant switching frequency, efficiency optimization is carried out by controlling phase shift quantity, and at most three degrees of control freedom optimization can be realized, so that the transmission power of the converter is constrained by optimization conditions, and the application of the converter in a wider power range is difficult to realize.
Disclosure of Invention
The invention aims to solve the technical problem of providing a four-degree-of-freedom efficiency optimization control method suitable for a bidirectional direct current converter of an electric locomotive, which can realize comprehensive optimization of the working efficiency of the bidirectional full-bridge DC-DC converter and remarkably improve the efficiency of the converter.
The technical scheme adopted for solving the technical problems is as follows: the four-degree-of-freedom efficiency optimization control method suitable for the bidirectional direct current converter of the electric locomotive comprises the following steps:
according to an inductance current model of the converter under triple phase shift control and soft switch constraint conditions, calculating to obtain the external phase shift quantity meeting all the soft switches of the switching tube, and taking the obtained external phase shift quantity meeting all the soft switches of the switching tube as the full soft switch constraint conditions;
obtaining a relation between a primary side internal phase shift angle and a secondary side internal phase shift angle which enable the reflux power to be zero under a full soft switch constraint condition according to a converter reflux power expression, and taking the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle as a zero reflux power constraint condition;
taking the external phase shift amount, the primary side internal phase shift angle and the secondary side internal phase shift angle as three degrees of freedom, combining a Lagrangian function and a power expression of the double-active full-bridge direct current converter under the control of the three degrees of freedom, introducing a switching frequency as a fourth control degree of freedom, and solving the expressions of the external phase shift amount, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency which meet the minimum current stress optimization on the basis of meeting the constraint conditions of a full soft switch and zero reflux power;
and optimally controlling the double-active full-bridge direct current converter based on the external phase shift, the internal phase shift angle of the primary side, the internal phase shift angle of the secondary side and the switching frequency.
The method for acquiring the constraint condition of the full soft switch specifically comprises the following steps: and the combination of the external phase shift quantity, the internal phase shift angle in the primary side and the internal phase shift angle in the secondary side is taken as independent variables, the inductance and the current expression at all the switch-on moments are solved by utilizing a segmentation analysis method, and then an inequality equation set is constructed by combining the current polarities required by realizing the soft switch at each moment, and the required external phase shift quantity is obtained by simultaneous solving and is taken as a constraint condition of the full soft switch.
The constraint conditions of the all-soft switch are as follows: d (D) 2 =0, where D 2 Indicating the amount of external phase shift.
The method for acquiring the zero-return power constraint condition comprises the following steps: and deriving a reflux power expression by taking the combination of the external phase shift, the primary side internal phase shift angle and the secondary side internal phase shift angle as independent variables, and then enabling the reflux power to be zero, and calculating the relation between the corresponding primary side internal phase shift angle and the secondary side internal phase shift angle to be used as a constraint condition of zero reflux power.
The zero return power constraint condition is: d (D) 1 ＝1-k(1-D 3 ) Wherein D is 1 Represents the internal phase shift angle in the primary side, D 3 And represents the secondary in-edge phase shift angle, and k represents the voltage conversion ratio of the double-active full-bridge direct current converter.
The Lagrangian function is expressed as: e=i peak (D 1 ,D 2 ,D 3 ,f s )+λ(P-P * ) Wherein E is a Lagrangian function, lambda is a Lagrangian multiplier, I peak (. Cndot.) is a function of current stress, D 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Represents the secondary in-edge phase shift angle, f s Represents the switching frequency, P is the actual power, P * For a given power.
The relation formula of the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency meeting the minimum current stress optimization is as follows:
Figure BDA0004092182060000031
Figure BDA0004092182060000032
wherein D is 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Represents the secondary in-edge phase shift angle, f s The switching frequency is represented by k, the voltage conversion ratio of the double-active full-bridge direct-current converter is represented by k, the transmission power of the double-active full-bridge direct-current converter is represented by P', the inductance value of the auxiliary inductor is represented by L, and U i Is the input voltage of the double active full bridge DC converter.
The double-active full-bridge DC-DC converter is optimally controlled based on the external phase shift quantity, the internal phase shift angle in the primary side, the internal phase shift angle in the secondary side and the switching frequency, and specifically comprises the following steps: the power transmission is realized by adjusting the switching frequency, the minimum current stress control is realized by adjusting the primary side phase shift angle, and the zero reflux power and the full soft switching optimization are realized by adjusting the external phase shift angle and the secondary side phase shift angle.
The technical scheme adopted for solving the technical problems is as follows: the utility model provides a four degrees of freedom efficiency optimization control device suitable for two-way DC converter of electric locomotive, include:
the first calculation module is used for calculating the external phase shift quantity meeting all the soft switching tubes based on an inductance current model of the converter under triple phase shift control and the soft switching constraint condition, and taking the obtained external phase shift quantity meeting all the soft switching tubes as the full soft switching constraint condition;
the second calculation module is used for obtaining the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle which enable the reflux power to be zero under the constraint condition of the full soft switch according to the reflux power expression of the converter, and taking the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle as the constraint condition of the zero reflux power;
the third calculation module is used for taking the external phase shift quantity, the primary side internal phase shift angle and the secondary side internal phase shift angle as three degrees of freedom, combining a Lagrangian function and a power expression of the double-active full-bridge direct current converter under the control of the three degrees of freedom, introducing a switching frequency as a fourth control degree of freedom, and solving the expressions of the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency which meet the minimum current stress optimization on the basis of meeting the constraint conditions of full soft switching and zero backflow power;
and the optimization control module is used for optimally controlling the double-active full-bridge direct current converter based on the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency.
The technical scheme adopted for solving the technical problems is as follows: the method comprises the steps that the four-degree-of-freedom efficiency optimization control method suitable for the bidirectional direct current converter of the electric locomotive is realized when the processor executes the computer program.
The technical scheme adopted for solving the technical problems is as follows: there is provided a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the four-degree-of-freedom efficiency optimization control method described above for use with a bi-directional dc converter of an electric locomotive.
Advantageous effects
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects: according to the three-degree-of-freedom soft switching condition and the reflux power model of the bidirectional full-bridge DC-DC converter in the electric locomotive, under the condition of guaranteeing all switching tube soft switching and zero reflux power, constraint conditions of three degrees of freedom D1, D2 and D3 are solved, and according to the Lagrangian function and the power model of the converter under the control of the three degrees of freedom, the combination of the optimal phase shift angle and the switching frequency which simultaneously meet the stress of the full soft switching, the zero reflux power and the minimum inductance current is obtained. The full soft switch, the zero reflux power, the minimum inductance current stress and the like are comprehensively considered, the switching frequency is introduced as the fourth control degree of freedom, the transmission power range of the converter can be expanded, the higher control degree of freedom and the more obvious optimization effect are achieved, the converter efficiency can be further improved, and the energy-saving and efficient operation of the converter system is realized. The four-degree-of-freedom efficiency optimization control method provided by the invention has the advantages of simple algorithm, simplicity and convenience in calculation, easiness in digitization and strong practicability.
Drawings
FIG. 1 is a flow chart of a four degree of freedom efficiency optimization control method for a bi-directional DC converter of an electric locomotive according to a first embodiment of the present invention;
FIG. 2 is a topology block diagram of a bi-directional full-bridge DC-DC converter according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of waveforms of switching tube control signals, primary-side bridge and secondary-side bridge AC side voltages and inductor current of the bidirectional full-bridge DC-DC converter under three-degree-of-freedom control in an embodiment of the invention;
FIG. 4 is a flow chart of optimization control in an embodiment of the invention;
FIG. 5 is a waveform diagram of primary and secondary full-bridge AC side voltage versus inductor current under conventional single phase shift control;
FIG. 6 is a waveform diagram of primary and secondary full-bridge AC side voltage versus inductor current under fundamental optimization control;
FIG. 7 is a waveform diagram of primary and secondary full-bridge AC side voltages and inductor current using an embodiment of the present invention;
FIG. 8 is a graph comparing efficiency of conventional single phase shift control, fundamental optimization control, and embodiments of the present invention.
Detailed Description
The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it is understood that various changes and modifications may be made by those skilled in the art after reading the teachings of the present invention, and such equivalents are intended to fall within the scope of the claims appended hereto.
The first embodiment of the invention relates to a four-degree-of-freedom efficiency optimization control method suitable for a bidirectional direct current converter of an electric locomotive, which is shown in fig. 1 and comprises the following steps:
and step 1, calculating to obtain the external phase shift quantity meeting all the switching tube soft switches based on an inductance current model of the converter under triple phase shift control and soft switch constraint conditions, and taking the obtained external phase shift quantity meeting all the switching tube soft switches as the full soft switch constraint conditions.
The method comprises the steps of taking the combination of the external phase shift, the internal phase shift angle in the primary side and the internal phase shift angle in the secondary side as independent variables, solving inductance and current expressions at all switch on time by utilizing a segmentation analysis method, constructing an inequality equation set by combining current polarities required by realizing soft switching at each time, and simultaneously solving to obtain the required external phase shift quantity as a constraint condition of the full soft switching.
Taking the topology structure of the bidirectional full-bridge DC-DC converter shown in fig. 2 as an example, since the soft switches of the switching tubes on two sides of the bidirectional full-bridge DC-DC converter are closely related to the inductor current direction, in order to realize the full-soft switch, the inductor current direction corresponding to the on time of each switch needs to be analyzed. As shown in fig. 3, according to the voltage-current waveform diagram of the down-converter controlled by the combination of the external phase shift amount, the internal phase shift angle in the primary side and the internal phase shift angle in the secondary side, the inductance current value at each time can be obtained by using a segmentation analysis method:
Figure BDA0004092182060000051
wherein i is L (t 0 )、i L (t 1 )、i L (t 2 )、i L (t 3 )、i L (t 4 ) Respectively represent t 0 、t 1 、t 2 、t 3 、t 4 Inductance current value at time, L is auxiliary inductance, U i For the input voltage of the converter, f s For switching frequency, D 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Representing the secondary in-edge phase shift angle.
According to the topological structure shown in fig. 2 and the soft switching conditions of the switching tubes on two sides, the required inductance current polarity of all the switching tube soft switches is obtained, and an inequality equation set is constructed:
Figure BDA0004092182060000061
solving the constraint conditions for realizing all the soft switching of the switching tube by combining the formula (1) and the formula (2), wherein the constraint conditions are only shifted by the external phase D 2 In relation to the desired external phase shift angle D 2 The method comprises the following steps:
D 2 ＝0 (3)
and 2, obtaining the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle which enable the reflux power to be zero under the constraint condition of the full soft switch according to the reflux power expression of the converter, and taking the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle as the constraint condition of the zero reflux power.
In the step, the combination of the external phase shift, the primary side phase shift angle and the secondary side phase shift angle is used as an independent variable to deduce a reflux power expression, the reflux power is set to be zero, and the relation between the corresponding primary side phase shift angle and the secondary side phase shift angle is calculated and used as a constraint condition of zero reflux power.
Referring to fig. 3, by integrating the product of the voltage and current over the power return period, the expression for the return power of the converter can be calculated as:
Figure BDA0004092182060000062
let equation (4) be zero, the phase shift constraint that the return power is zero can be obtained:
D 1 ＝1-k(1-D 3 ) (5)
and 3, taking the external phase shift, the internal phase shift angle in the primary side and the internal phase shift angle in the secondary side as three degrees of freedom, combining a Lagrangian function and a power expression of the double-active full-bridge DC-DC converter under the control of the three degrees of freedom, introducing a switching frequency as a fourth degree of freedom, and solving the expressions of the external phase shift, the internal phase shift angle in the primary side, the internal phase shift angle in the secondary side and the switching frequency which meet the minimum current stress optimization on the basis of meeting the constraint conditions of full soft switching and zero backflow power.
The step uses the full soft switch and zero return power as constraint conditions, uses the phase shift quantity (D 1 ，D 2 ，D 3 ) And a switching frequency f s And as four degrees of freedom, combining the Lagrangian function and the converter power model to minimize the inductance current stress, and solving a phase shift amount combination and a switching frequency expression which meet the multi-objective optimization. Specifically:
to optimize the current stress at a given output power, the current stress is expressed as a function of the phasor and the switching frequency, and a lagrangian function is constructed as:
E＝I peak (D 1 ,D 2 ,D 3 ,f s )+λ(P-P * ) (6)
wherein E is a Lagrangian function, lambda is a Lagrangian multiplier, I peak (. Cndot.) is the current stress function, P is the actual power of the bi-directional full-bridge DC-DC converter, P * Is a given transmission power of the bi-directional full-bridge DC-DC converter.
Deriving the independent variable in the formula (6), combining the constraint conditions of the full soft switch and the zero return power, and calculating to obtain the three degrees of freedom (D) simultaneously meeting the full soft switch, the zero return power and the minimum inductance current stress 1 ,D 2 ,D 3 ) And an optimal combination of fourth degree of freedom switching frequencies:
Figure BDA0004092182060000071
Figure BDA0004092182060000072
and 4, optimally controlling the double-active full-bridge DC-DC converter based on the external phase shift, the internal phase shift angle in the primary side, the internal phase shift angle in the secondary side and the switching frequency.
Referring to the optimal combination of the phase shift amount and the switching frequency which simultaneously satisfy the full soft switching, the zero backflow power and the minimum inductance current stress and fig. 4, the voltage conversion ratio of the converter can be calculated by collecting the input voltage and the output voltage of the converter in real time, and the required optimal phase shift amount can be further obtained. In order to compensate the influence of inaccurate parameters such as leakage inductance of a transformer, transformation ratio of the transformer and the like on output voltage, a PI controller is adopted to adjust the switching frequency so as to ensure that the output voltage reaches the reference voltage, and the switching frequency f is adjusted s Realizing power transmission by adjusting the phase shift angle D in the primary side 1 Achieving minimum current stress control by adjusting the external phase shift angle D 2 And the secondary in-edge phase shift angle D 3 Zero return power and full soft switching optimization are achieved.
As shown in fig. 5 to 7, compared with the conventional single-phase shift control and fundamental wave optimization control method, the method of the embodiment has better soft switching characteristics and can simultaneously realize zero return current power and minimum inductor current stress under the same voltage conversion ratio and transmission power. Compared with other optimized control methods, the control method of the embodiment realizes the optimization of zero reflux power and minimum current stress on the premise of ensuring soft switching and introduces the switching frequency f s As a fourth degree of freedom to extend the power transmission range of the converter, the influence of the efficiency optimization constraint on the converter transmission power is solved. As shown in fig. 8, when the voltage parameters are not matched, the method of the embodiment has the highest efficiency in the full power range, and the efficiency is improved most obviously under the light load working condition.
It is easy to find that the constraint conditions of the three degrees of freedom D1, D2 and D3 are solved according to the three degrees of freedom soft switching conditions and the reflux power model of the bidirectional full-bridge DC-DC converter in the electric locomotive under the condition of guaranteeing all the soft switching tubes and zero reflux power, and the optimal phase shift angle combination and the combination of switching frequency which simultaneously meet the stress of the full soft switching, the zero reflux power and the minimum inductive current are obtained according to the Lagrangian function and the power model of the converter under the control of the three degrees of freedom. The full soft switch, the zero reflux power, the minimum inductance current stress and the like are comprehensively considered, the switching frequency is introduced as the fourth control degree of freedom, the transmission power range of the converter can be expanded, the higher control degree of freedom and the more obvious optimization effect are achieved, the converter efficiency can be further improved, and the energy-saving and efficient operation of the converter system is realized. The four-degree-of-freedom efficiency optimization control method provided by the invention has the advantages of simple algorithm, simplicity and convenience in calculation, easiness in digitization and strong practicability.
A second embodiment of the present invention relates to a four-degree-of-freedom efficiency optimization control device suitable for a bidirectional dc converter of an electric locomotive, comprising:
the first calculation module is used for calculating the external phase shift quantity meeting all the soft switching tubes based on an inductance current model of the converter under triple phase shift control and the soft switching constraint condition, and taking the obtained external phase shift quantity meeting all the soft switching tubes as the full soft switching constraint condition;
the second calculation module is used for obtaining the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle which enable the reflux power to be zero under the constraint condition of the full soft switch according to the reflux power expression of the converter, and taking the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle as the constraint condition of the zero reflux power;
the third calculation module is used for taking the external phase shift quantity, the primary side internal phase shift angle and the secondary side internal phase shift angle as three degrees of freedom, combining a Lagrangian function and a power expression of the double-active full-bridge direct current converter under the control of the three degrees of freedom, introducing a switching frequency as a fourth control degree of freedom, and solving the expressions of the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency which meet the minimum current stress optimization on the basis of meeting the constraint conditions of full soft switching and zero backflow power;
and the optimization control module is used for optimally controlling the double-active full-bridge direct current converter based on the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency.
And the first calculation module uses the combination of the external phase shift quantity, the internal phase shift angle in the primary side and the internal phase shift angle in the secondary side as independent variables, solves the inductance and the current expression at all the switching-on moments by utilizing a segmentation analysis method, and then combines the current polarity required by realizing the soft switch at each moment to construct an inequality equation set, and solves the required external phase shift quantity simultaneously to serve as a constraint condition of the full soft switch.
The constraint conditions of the all-soft switch are as follows: d (D) 2 =0, where D 2 Indicating the amount of external phase shift.
And the second calculation module derives a reflux power expression by taking the combination of the external phase shift, the primary side internal phase shift and the secondary side internal phase shift as independent variables, and then enables the reflux power to be zero, and calculates the relation between the corresponding primary side internal phase shift and the secondary side internal phase shift as a constraint condition of zero reflux power.
The zero return power constraint condition is: d (D) 1 ＝1-k(1-D 3 ) Wherein D is 1 Represents the internal phase shift angle in the primary side, D 3 And represents the secondary in-edge phase shift angle, and k represents the voltage conversion ratio of the double-active full-bridge direct current converter.
The Lagrangian function is expressed as: e=i peak (D 1 ,D 2 ,D 3 ,f s )+λ(P-P * ) Wherein E is a Lagrangian function, lambda is a Lagrangian multiplier, I peak (. Cndot.) is a function of current stress, D 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Represents the secondary in-edge phase shift angle, f s Represents the switching frequency, P is the actual power, P * For a given power.
The relation formula of the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency meeting the minimum current stress optimization is as follows:
Figure BDA0004092182060000091
Figure BDA0004092182060000092
wherein D is 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Represents the secondary in-edge phase shift angle, f s Represents the switching frequency, k represents the double active full bridge DCThe voltage conversion ratio of the converter, P' is the transmission power of the double-active full-bridge direct-current converter, L is the inductance value of the auxiliary inductor, U i Is the input voltage of the double active full bridge DC converter.
The optimization control module realizes power transmission by adjusting the switching frequency, minimum current stress control by adjusting the primary side internal phase shift angle, zero reflux power and full soft switching optimization by adjusting the external phase shift angle and the secondary side internal phase shift angle.
A third embodiment of the present invention is directed to an electronic device including a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the four-degree-of-freedom efficiency optimization control method of the first embodiment applicable to a bi-directional dc converter of an electric locomotive when executing the computer program.
A fourth embodiment of the present invention is directed to a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the four-degree-of-freedom efficiency optimization control method of the first embodiment adapted to a bi-directional dc converter of an electric locomotive.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the invention can be realized by adopting various computer languages, such as object-oriented programming language Java, an transliteration script language JavaScript and the like.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (11)

1. The four-degree-of-freedom efficiency optimization control method suitable for the bidirectional direct current converter of the electric locomotive is characterized by comprising the following steps of:
based on an inductance current model of the converter under triple phase shift control and soft switch constraint conditions, calculating to obtain the external phase shift quantity meeting all the soft switches of the switching tube, and taking the obtained external phase shift quantity meeting all the soft switches of the switching tube as the full soft switch constraint conditions;
obtaining a relation between a primary side internal phase shift angle and a secondary side internal phase shift angle which enable the reflux power to be zero under a full soft switch constraint condition according to a converter reflux power expression, and taking the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle as a zero reflux power constraint condition;
taking the external phase shift amount, the primary side internal phase shift angle and the secondary side internal phase shift angle as three degrees of freedom, combining a Lagrangian function and a power expression of the double-active full-bridge direct current converter under the control of the three degrees of freedom, introducing a switching frequency as a fourth control degree of freedom, and solving the expressions of the external phase shift amount, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency which meet the minimum current stress optimization on the basis of meeting the constraint conditions of a full soft switch and zero reflux power;
and optimally controlling the double-active full-bridge direct current converter based on the external phase shift, the internal phase shift angle of the primary side, the internal phase shift angle of the secondary side and the switching frequency.
2. The four-degree-of-freedom efficiency optimization control method suitable for the bidirectional direct current converter of the electric locomotive according to claim 1, wherein the method for acquiring the constraint condition of the all-soft switch is specifically as follows: and the combination of the external phase shift quantity, the internal phase shift angle in the primary side and the internal phase shift angle in the secondary side is taken as independent variables, the inductance and the current expression at all the switch-on moments are solved by utilizing a segmentation analysis method, and then an inequality equation set is constructed by combining the current polarities required by realizing the soft switch at each moment, and the required external phase shift quantity is obtained by simultaneous solving and is taken as a constraint condition of the full soft switch.
3. Bidirectional DC converter for electric locomotive according to claim 2The four-degree-of-freedom efficiency optimization control method is characterized in that the constraint conditions of the all-soft switch are as follows: d (D) 2 =0, where D 2 Indicating the amount of external phase shift.
4. The four-degree-of-freedom efficiency optimization control method suitable for the bidirectional direct current converter of the electric locomotive according to claim 1, wherein the method for acquiring the zero-return power constraint condition is specifically as follows: and deriving a reflux power expression by taking the combination of the external phase shift, the primary side internal phase shift angle and the secondary side internal phase shift angle as independent variables, and then enabling the reflux power to be zero, and calculating the relation between the corresponding primary side internal phase shift angle and the secondary side internal phase shift angle to be used as a constraint condition of zero reflux power.
5. The four-degree-of-freedom efficiency optimization control method for a bi-directional dc converter of an electric locomotive according to claim 4, wherein the zero-return power constraint condition is: d (D) 1 ＝1-k(1-D 3 ) Wherein D is 1 Represents the internal phase shift angle in the primary side, D 3 And represents the secondary in-edge phase shift angle, and k represents the voltage conversion ratio of the double-active full-bridge direct current converter.
6. The four-degree-of-freedom efficiency optimization control method for a bi-directional dc converter of an electric locomotive according to claim 1, wherein the lagrangian function is expressed as: e=i peak (D 1 ,D 2 ,D 3 ,f s )+λ(P-P * ) Wherein E is a Lagrangian function, lambda is a Lagrangian multiplier, I peak (. Cndot.) is a function of current stress, D 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Represents the secondary in-edge phase shift angle, f s Represents the switching frequency, P is the actual power, P * For a given power.
7. The four-degree-of-freedom efficiency optimization control method for a bi-directional DC converter of an electric locomotive according to claim 1, wherein said external phase shift satisfying minimum current stress optimizationThe relation among the quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency is as follows:
Figure FDA0004092182050000021
Figure FDA0004092182050000022
wherein D is 1 Represents the internal phase shift angle in the primary side, D 2 Represents the external phase shift amount D 3 Represents the secondary in-edge phase shift angle, f s The switching frequency is represented by k, the voltage conversion ratio of the double-active full-bridge direct-current converter is represented by k, the transmission power of the double-active full-bridge direct-current converter is represented by P', the inductance value of the auxiliary inductor is represented by L, and U i Is the input voltage of the double active full bridge DC converter.
8. The four-degree-of-freedom efficiency optimization control method for a bidirectional direct current converter of an electric locomotive according to claim 1, wherein the optimizing control of the double-active full-bridge direct current converter based on the external phase shift amount, the internal phase shift angle in the primary side, the internal phase shift angle in the secondary side and the switching frequency is specifically as follows: the power transmission is realized by adjusting the switching frequency, the minimum current stress control is realized by adjusting the primary side phase shift angle, and the reflux power and the full soft switching optimization are realized by adjusting the external phase shift angle and the secondary side phase shift angle.
9. A four-degree-of-freedom efficiency optimization control device based on a bidirectional DC converter suitable for an electric locomotive is characterized in that,
comprising the following steps:
the first calculation module is used for calculating the external phase shift quantity meeting all the soft switching tubes based on an inductance current model of the converter under triple phase shift control and the soft switching constraint condition, and taking the obtained external phase shift quantity meeting all the soft switching tubes as the full soft switching constraint condition;
the second calculation module is used for obtaining the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle which enable the reflux power to be zero under the constraint condition of the full soft switch according to the reflux power expression of the converter, and taking the relation between the primary side internal phase shift angle and the secondary side internal phase shift angle as the constraint condition of the zero reflux power;
the third calculation module is used for taking the external phase shift quantity, the primary side internal phase shift angle and the secondary side internal phase shift angle as three degrees of freedom, combining a Lagrangian function and a power expression of the double-active full-bridge direct current converter under the control of the three degrees of freedom, introducing a switching frequency as a fourth control degree of freedom, and solving the expressions of the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency which meet the minimum current stress optimization on the basis of meeting the constraint conditions of full soft switching and zero backflow power;
and the optimization control module is used for optimally controlling the double-active full-bridge direct current converter based on the external phase shift quantity, the primary side internal phase shift angle, the secondary side internal phase shift angle and the switching frequency.
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor, when executing the computer program, performs the steps of the four degree-of-freedom efficiency optimization control method for a bi-directional dc converter of an electric locomotive as claimed in any one of claims 1-8.
11. A computer readable storage medium having stored thereon a computer program, wherein the computer program when executed by a processor performs the steps of the four degree of freedom efficiency optimization control method for a bi-directional dc converter of an electric locomotive as claimed in any one of claims 1-8.
CN202310155514.3A 2023-02-23 2023-02-23 Four-degree-of-freedom efficiency optimization control method suitable for bidirectional direct current converter of electric locomotive Pending CN116317595A (en)

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