CN114970368A - Efficiency optimization method and device for double active bridges, electronic equipment and storage medium - Google Patents
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Abstract
The invention discloses a method and a device for optimizing efficiency of double active bridges, electronic equipment and a storage medium, belonging to the technical field of power electronics, wherein the method comprises the following steps: establishing a Fourier form based switching function, wherein the Fourier form based switching function is a function of the total number of harmonics and a phase shift angle; establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by utilizing a switch function based on a Fourier form; optimizing the target function to obtain the optimal value of the total number of the harmonics and the optimal value of the phase shift angle, so that the inductive current of the inductive current dynamic time domain harmonic model is the minimum and the capacitive current of the capacitive current dynamic time domain harmonic model is the minimum; the minimum inductor current and the minimum capacitor current are obtained. According to the invention, the inductance current dynamic time domain harmonic model and the capacitance current dynamic time domain harmonic model are established by a harmonic modeling method, so that the models are easier to solve, the calculated amount is small, and the implementation is easy.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a method and a device for optimizing efficiency of double active bridges, electronic equipment and a storage medium.
Background
In order to improve the power efficiency of the dual active bridge dc converter, the related art focuses on research on various power efficiency optimization strategies. The conventional efficiency optimization method based on the power loss model is to realize the optimal efficiency control by establishing an accurate power loss model. However, this optimization method has a problem of computational complexity, especially under complex operating conditions, such as those facing varying load conditions and voltage conversion ratio conditions, which increases the difficulty of achieving optimal efficiency.
Disclosure of Invention
In view of this, embodiments of the present invention provide a method and an apparatus for optimizing efficiency of a dual active bridge, an electronic device, and a storage medium, so as to solve the problems of complex calculation and high implementation difficulty of the existing method for optimizing efficiency of a dual active bridge.
According to a first aspect, an embodiment of the present invention provides an efficiency optimization method for a dual active bridge, where the method includes:
establishing a fourier form based switching function that is a function of the total number of harmonics and the phase shift angle;
establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by utilizing the switch function based on the Fourier form;
optimizing the objective function based on a preset constraint condition to obtain an optimal value of the total number of the harmonics and an optimal value of the phase shift angle, so that the inductance current of the inductance current dynamic time domain harmonic model is minimum and the capacitance current of the capacitance current dynamic time domain harmonic model is minimum;
and acquiring the minimum inductance current and the minimum capacitance current.
Optionally, the constraint condition includes at least one of: the output power is constant, the calculation time does not exceed the maximum allowable value, and the total number of harmonics is an integer.
Optionally, in a case that the constraint condition includes that the output power is constant, the method further includes:
establishing a relation function between the switch state and each output voltage;
using the fourier-form based switching function and the relationship function, a function of the output power in harmonic form is established.
Optionally, the establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model by using the fourier-form-based switching function includes:
establishing a dynamic time domain expression of the double active bridges by using the Fourier form-based switching function expression;
and deducing a time domain expression of the inductive current and a time domain expression of the capacitive current by using the dynamic time domain expression of the double driving bridges, wherein the time domain expression of the inductive current is used as the dynamic time domain harmonic model of the inductive current, and the time domain expression of the capacitive current is used as the dynamic time domain harmonic model of the capacitive current.
Optionally, the deriving the time domain expression of the inductor current and the time domain expression of the capacitor current by using the dynamic time domain expression of the dual active bridge includes:
converting the dynamic time domain expression of the double driving bridges into a phase domain expression of the double driving bridges;
deriving a phase domain expression of the inductive current based on the phase domain expression of the double active bridges;
converting the phase domain expression of the inductive current into a time domain expression of the inductive current;
and deriving a time domain expression of the capacitance current based on the time domain expression of the inductance current.
Optionally, the establishing a dynamic time domain expression of the dual active bridge by using the fourier-form-based switching function expression includes:
establishing a relation function between the switch state and each output voltage;
and establishing a dynamic time domain expression of the double active bridges by using the relation function and the Fourier form-based switching function expression.
Optionally, the optimizing the objective function based on a preset constraint condition to obtain an optimal value of the total number of harmonics and an optimal value of the phase shift angle includes:
s201: randomly generating an initial population with the size of N as a parent population;
s202: after the parent population is subjected to non-dominated sorting, obtaining a first generation offspring population through selection, crossing and mutation operations of a genetic algorithm; n is a positive integer;
s203: from the second generation, merging the parent population and the offspring population into a sequencing population with the scale of 2N, performing rapid non-dominant sequencing, simultaneously performing congestion degree calculation on individuals in each non-dominant layer, and selecting the individuals according to the non-dominant relationship and the congestion degree of the individuals to form a new parent population;
s204: and repeating the steps S202 and S203 for the new parent population until the maximum iteration times are met, and stopping calculation to obtain the optimal values of the phase shift angle and the total number of harmonics.
According to a second aspect, an embodiment of the present invention provides an efficiency optimization apparatus for a dual active bridge, including:
a switching function establishing module for establishing a Fourier form based switching function, the Fourier form based switching function being a function of the total number of harmonics and a phase shift angle;
the harmonic model establishing module is used for establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by utilizing the switch function based on the Fourier form;
the optimization module is used for optimizing the objective function based on a preset constraint condition to obtain an optimal value of the total number of the harmonics and an optimal value of the phase shift angle, so that the inductance current of the inductance current dynamic time domain harmonic model is minimum and the capacitance current of the capacitance current dynamic time domain harmonic model is minimum;
and the obtaining module is used for obtaining the minimum inductance current and the minimum capacitance current.
According to a third aspect, an embodiment of the present invention provides an electronic device, including:
a memory and a processor, the memory and the processor being communicatively connected to each other, the memory being configured to store a computer program, and the computer program, when executed by the processor, implementing any of the above-mentioned methods for efficiency optimization of a dual-active bridge according to the first aspect.
According to a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, where the computer-readable storage medium is used for storing a computer program, and when the computer program is executed by a processor, the computer program implements any one of the above-mentioned efficiency optimization methods for a dual active bridge according to the first aspect.
According to the efficiency optimization method, the efficiency optimization device, the electronic equipment and the storage medium of the double-active-bridge converter, the inductance current dynamic time domain harmonic model and the capacitance current dynamic time domain harmonic model are established based on the harmonic modeling method, and the minimization of the inductance current and the capacitance current is controlled through the optimization algorithm, so that the power losses such as the loss of a switching tube, the loss of a transformer, the loss of a capacitor and the like can be reduced, and the efficiency of the double-active-bridge converter is improved. And an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model are built based on the harmonic modeling method, so that the models can be solved more easily, and the implementation is easier.
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The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:
fig. 1 is a schematic flowchart of an efficiency optimization method for a dual active bridge according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a dual active bridge model;
FIG. 3 is a schematic diagram of an ideal waveform of a dual active bridge;
fig. 4 is a schematic structural diagram of an efficiency optimization apparatus for a dual active bridge according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the following examples, "plurality" means two or more unless specifically limited otherwise.
Referring to fig. 1, an embodiment of the present invention provides a method for optimizing efficiency of a dual active bridge, where the method includes:
s101: establishing a Fourier form based switching function that is a function of the total number of harmonics K and a phase shift angle θ;
s102: establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by utilizing the switch function based on the Fourier form;
s103: optimizing the objective function based on a preset constraint condition to obtain an optimal value of the total number K of the harmonics and an optimal value of the phase shift angle theta, so that the inductance current of the inductance current dynamic time domain harmonic model is minimum and the capacitance current of the capacitance current dynamic time domain harmonic model is minimum;
s104: and acquiring the minimum inductance current and the minimum capacitance current.
In the embodiment of the invention, the inductance current dynamic time domain harmonic model and the capacitance current dynamic time domain harmonic model are established based on a harmonic modeling method, and the minimization of the inductance current and the capacitance current is controlled through an optimization algorithm, so that the power loss such as the loss of a switching tube, the loss of a transformer, the loss of a capacitor and the like can be reduced, and the efficiency of the double-active-bridge converter is improved. And an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model are built based on the harmonic modeling method, so that the models can be solved more easily, and the implementation is easier.
In some specific embodiments, the establishing an inductance current dynamic time-domain harmonic model and a capacitance current dynamic time-domain harmonic model by using the fourier-form-based switching function includes:
establishing a dynamic time domain expression of the double active bridges by using the Fourier form-based switching function expression;
and deducing a time domain expression of the inductive current and a time domain expression of the capacitive current by using the dynamic time domain expression of the double driving bridges, wherein the time domain expression of the inductive current is used as the dynamic time domain harmonic model of the inductive current, and the time domain expression of the capacitive current is used as the dynamic time domain harmonic model of the capacitive current.
In some optional specific embodiments, the deriving the time domain expression of the inductor current and the time domain expression of the capacitor current by using the dynamic time domain expression of the dual active bridge includes:
converting the dynamic time domain expression of the double driving bridges into a phase domain expression of the double driving bridges;
deriving a phase domain expression of the inductive current based on the phase domain expression of the double active bridges;
converting the phase domain expression of the inductive current into a time domain expression of the inductive current;
and deriving a time domain expression of the capacitance current based on the time domain expression of the inductance current.
The model and ideal waveform of the double active bridge are shown in fig. 2 and fig. 3, the double active bridge comprises 8 switching tubes S1-S8, wherein the switching tubes S1-S4 form a full bridge, the switching tubes S5-S8 form another full bridge, and the input voltage of the former full bridge is V in An output voltage of V T1 The input voltage of the other full bridge is V T2 An output voltage of V out The double-driving-bridge model further comprises a transformer between two full bridges, an inductor L, a parasitic resistor R and an output capacitor C, wherein the inductor L, the parasitic resistor R and the output capacitor C are connected in series at the output end of the previous full bridge, and the turn ratio of the transformer is n: 1. according to fourier theory, any periodic signal can be represented by an infinite series consisting of a sine function and a cosine function, assuming that the function f (x) can be extended to a uniformly converging triangular series over the entire interval, as shown in equation (1), where the coefficient a 0 、a k And b k Are respectively as
Therefore, a fourier-form-based switching function expression can be derived as an expression (2), wherein the accuracy of the dual-active-bridge time domain state space model, that is, the accuracy of the inductance current dynamic time domain harmonic model and the capacitance current dynamic time domain harmonic model, is determined by selecting a total number K of harmonics, and when the K value is larger, the fitting degree is higher, but the calculation amount is larger.
Wherein, the first and the second end of the pipe are connected with each other,
f s is the switching frequency of the switching tubes in the dual active bridge.
Firstly, because the state variables in the dual-active bridge time domain model are driven by binary value switch functions, the dynamic model contains discrete and continuous time functions at the same time, so that the dynamic equation is difficult to solve analytically. According to the embodiment of the invention, a double-driving-bridge time domain state space model is built based on a harmonic modeling method, and then an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model are deduced based on the double-driving-bridge time domain state space model, so that the models are easier to solve, and are easier to realize. In addition, the influence of higher harmonics in the switching function on the output of the multilevel converter can be considered by constructing a harmonic model.
Secondly, the conventional dual active bridge dc converter mainly includes 3 kinds of power losses, i.e. switching tube loss, magnetic element loss, and capacitance loss. Switching tube losses can be divided into switching losses, conduction losses and gate drive losses. The magnetic element losses are concentrated in the transformer and series inductor, including copper and iron losses. The conduction loss in the switching tube loss is proportional to the root mean square value of current flowing through the switching tube in conduction time, and the capacitance loss is proportional to the root mean square value of capacitance current, so that a double-driving-bridge time domain state space model is established based on a harmonic modeling method, then an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model are derived based on the double-driving-bridge time domain state space model, and the minimization of inductance current and capacitance current is controlled through an optimization algorithm, so that the power losses such as the switching tube loss, transformer loss, capacitance loss and the like can be reduced, and the efficiency of the double-driving-bridge converter is improved.
In some optional specific embodiments, the establishing a dynamic time domain expression of the dual active bridge by using the fourier-form-based switching function expression includes:
establishing a relation function between the switch state and each output voltage;
and establishing a dynamic time domain expression of the double active bridges by using the relation function and the Fourier form-based switching function expression.
For example, the specific process of establishing the inductance current dynamic time domain harmonic model and the capacitance current dynamic time domain harmonic model by using the fourier-form-based switching function may be:
establishing a relation function between the switch state and each output voltage, as shown in formulas (3) and (4):
V T1 (t)＝2V DC [S 1 (t)-S 3 (t)]＝V in [S 1 (t)-S 3 (t)] (3)
V T2 (t)＝2V DC [S 5 (t)-S 7 (t)]＝V out [S 5 (t)-S 7 (t)] (4)
the output voltages corresponding to the switch states of the switches are shown in the following table:
for the dual active bridge model shown in fig. 2, assuming no loss, the dual active bridge inductor voltage expression is formula (5) and the inductor current expression is formula (6), regardless of the transformer parasitic capacitance:
v L (t)＝v T1 (t)-nv T2 (t) (5)
establishing a dynamic time domain expression of the double active bridges by using the relation functions shown in the expressions (3) and (4) and the switching function based on the Fourier form shown in the expression (2), as shown in the expression (7):
wherein, R is the parasitic resistance of the double active bridge model.
After the dynamic time domain expression of the double active bridges shown in the formula (7) is converted into the phase domain expression, the phase domain expression of the inductive current can be deduced, and then the phase domain expression of the inductive current is converted into the time domain expression of the inductive current, as shown in the formula (8):
wherein, the first and the second end of the pipe are connected with each other,
the capacitance current time domain expression can be derived through the inductance current time domain expression shown in the formula (8), as shown in the formula (9):
wherein i out (t) output Current of the double active bridge model, i Load (t) is the load current.
In some embodiments, the constraints include at least one of: the output power is constant, the calculation time does not exceed the maximum allowable value, and the total number K of harmonics is an integer.
In some specific embodiments, the objective function may be represented by the following equation (10):
wherein, P ref As a constant value of output power, t cal To calculate time, t max To calculate the maximum allowable value of time.
In some specific embodiments, in a case where the constraint condition includes that the output power is constant, the method further includes:
establishing a relation function between the switch state and each output voltage;
using the fourier based form of the switching function and the relation function to establish a function of the output power in harmonic form.
Referring to FIG. 3 and equation (6), according to the inductor current at t 0 To t 1 And t 1 To t 2 And the average transmission power expression in one period obtained by integrating the instantaneous transmission power expressions of the double active bridges can deduce that the transmission power is-pi<θ<The expression of π is as shown in formula (11):
from the relational functions of the switching states and the respective output voltages shown in the above equations (3) and (4) and the switching function based on the fourier form shown in the above equation (2), a function of the output power in the form of a harmonic based on the phase shift angle θ and the total number K of harmonics is obtained as shown in equation 12:
the embodiment of the invention selects the inductance current and the capacitance current value as optimization indexes, establishes a target function taking the inductance current and the capacitance current value as optimization objects, and has the constraint condition of constant output power, the calculation time does not exceed the maximum allowable value, and the total number K of harmonic waves is an integer.
In some specific embodiments, the optimizing the objective function based on a preset constraint condition to obtain an optimal value of the total number K of harmonics and an optimal value of the phase shift angle θ includes:
s201: randomly generating an initial population with the size of N as a parent population;
s202: after the parent population is subjected to non-dominated sorting, obtaining a first generation offspring population through selection, crossing and mutation operations of a genetic algorithm; n is a positive integer;
s203: from the second generation, merging the parent population and the offspring population into a sequencing population with the scale of 2N, performing rapid non-dominant sequencing, simultaneously performing congestion degree calculation on individuals in each non-dominant layer, and selecting the individuals according to the non-dominant relationship and the congestion degree of the individuals to form a new parent population;
s204: and repeating the steps S202 and S203 for the new parent population until the maximum iteration times are met, and stopping calculation to obtain the optimal values of the phase shift angle theta and the total harmonic number K.
Wherein, selecting: the selection operator is applied to the population. The selection operation is to directly inherit the optimized individuals to the next generation or generate new individuals through pairing crossing and then inherit the new individuals to the next generation. And (3) crossing: the crossover operator is applied to the population. Mutation: and (4) acting mutation operators on the population. Mutation is the alteration of gene values at certain loci in a population of individuals.
Regarding the fast non-dominated sorting, the specific process is as follows:
(203-11) calculating a dominant count n for each individual in the pooled population g (i.e., the number of solutions that dominate the g solution) and the set S of all solutions dominated by the g solution g . It is specified that the dominant counts of all solutions at the first leading face are 0, and for each solution g whose dominant count is 0, the set S of solutions dominated by it g The dominance count of all solutions in (1);
(203-12) separating the solutions in the set P, that is, the solution of the second front surface, if the dominance count of a solution among the solutions dominated by the solution g becomes 0 after the above steps;
(203-13) repeating the above steps (203-11), (203-12) for the solutions in the set P, then all solutions in the third leading face can be found; and so on until all solutions are placed in their respective frontplanes.
Wherein, with regard to domination: for m objective functions h j (y), j ═ 1,2 … m, given any two decision variables X A ，X B If for any j, there is h j (X A )≤h j (X B ) Then call X A Dominating X B Otherwise it is called X A Do not dominate X B 。
In the embodiment of the invention, in order to ensure the diversity of the population, even if the solution is more uniformly distributed in the target space, the concept of the crowding degree is introduced. The calculation process of the crowding degree comprises the following steps:
(203-21) for the first individual, respectively taking the nearest individuals l-1 and l +1 on both sides of the first individual, using two points of l-1 and l +1 as vertexes to make a rectangle, and the crowdedness is the perimeter of the rectangle. Here, the crowdedness of the individual at the edge is set to + ∞.
(203-22) calculating the crowdedness of the individuals in each leading surface and sorting all the individuals in the same leading surface in descending order of the crowdedness.
(203-23) after the descending sorting of the crowdedness degree is completed, selecting individuals from the first front face until the total number of the selected individuals reaches N, and forming a new parent population by the selected N individuals.
The embodiment of the invention adopts the NSGA-II algorithm to control the current values of the inductance current and the capacitance current of the double driving bridges, searches the optimal control variable for the double driving bridge direct current converter, reduces the power loss of the converter and improves the efficiency characteristic of the converter. The intelligent optimization algorithm has less limitation on the optimization problem, only needs the information value of the objective function without other obvious limitations, and can be used for solving the problem that the convexity and the micromanipulation are not satisfied, solving the problem that the analytic expression is not available and solving the problem that the constraint is not obviously continuous compared with the traditional optimization algorithm.
In the above embodiments, the objective function is optimized by using the NSGA-II (Non-dominant Genetic Algorithm) algorithm, and in some alternative embodiments, other optimization Algorithms may be used.
In summary, the embodiment of the invention establishes the dual-active-bridge time domain state space model based on the harmonic modeling method, and then obtains the minimum value corresponding to the inductive current and the capacitive current through the intelligent optimization algorithm, so that the loss of the dual-active-bridge converter in energy transmission is reduced, and the efficiency optimization of the converter is realized.
Accordingly, referring to fig. 4, an embodiment of the present invention provides an efficiency optimization apparatus for dual active bridges, including:
a switching function establishing module 401 for establishing a fourier form based switching function, which is a function of the total number of harmonics and a phase shift angle;
a harmonic model establishing module 402, configured to establish an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by using the fourier-form-based switching function;
an optimizing module 403, configured to optimize the objective function based on a preset constraint condition to obtain an optimal value of the total number of harmonics and an optimal value of the phase shift angle, so that an inductor current of the inductor current dynamic time domain harmonic model is minimum and a capacitor current of the capacitor current dynamic time domain harmonic model is minimum;
an obtaining module 404, configured to obtain the minimum inductor current and the minimum capacitor current.
In the embodiment of the invention, the inductance current dynamic time domain harmonic model and the capacitance current dynamic time domain harmonic model are established based on the harmonic modeling method, and the minimization of the inductance current and the capacitance current is controlled by an optimization algorithm, so that the power loss such as the switching tube loss, the transformer loss, the capacitance loss and the like can be reduced, and the efficiency of the double-active-bridge converter is improved. And an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model are built based on the harmonic modeling method, so that the models can be solved more easily, and the implementation is easier.
In some specific embodiments, the constraint includes at least one of: the output power is constant, the calculation time does not exceed the maximum allowable value, and the total number of harmonics is an integer.
In some specific embodiments, in a case where the constraint condition includes that the output power is constant, the apparatus further includes:
the relation function establishing module is used for establishing a relation function between the switch state and each output voltage;
and the output power function establishing module is used for establishing a function of the output power in the form of harmonic waves by using the switch function based on the Fourier form and the relation function.
In some specific embodiments, the harmonic model building module 402 includes:
the establishing unit is used for establishing a dynamic time domain expression of the double active bridges by using the Fourier form-based switching function expression;
and the obtaining unit is used for deducing the time domain expression of the inductive current and the time domain expression of the capacitive current by using the dynamic time domain expression of the double driving bridges, wherein the time domain expression of the inductive current is used as the dynamic time domain harmonic model of the inductive current, and the time domain expression of the capacitive current is used as the dynamic time domain harmonic model of the capacitive current.
In some specific embodiments, the obtaining unit includes:
the first conversion subunit is used for converting the dynamic time domain expression of the double active bridges into a phase domain expression of the double active bridges;
the first obtaining subunit is used for deducing a phase domain expression of the inductive current based on the phase domain expression of the double active bridges;
the second conversion subunit is used for converting the phase domain expression of the inductive current into a time domain expression of the inductive current;
and the second obtaining subunit is used for deducing the time domain expression of the capacitance current based on the time domain expression of the inductance current.
In some specific embodiments, the establishing unit includes:
the first establishing subunit is used for establishing a relation function between the switch state and each output voltage;
and the second establishing subunit is used for establishing a dynamic time domain expression of the double active bridges by using the relation function and the Fourier form-based switching function expression.
In some specific embodiments, the optimization module 403 includes:
a first generation unit for randomly generating an initial population of size N as a parent population;
the second generation unit is used for obtaining a first generation filial population through selection, crossing and mutation operations of a genetic algorithm after the non-dominated sorting is carried out on the parent population; n is a positive integer;
the third generation unit is used for combining the parent population and the offspring population from the second generation to obtain a sequencing population with the size of 2N, performing rapid non-dominant sequencing, simultaneously performing crowding degree calculation on the individuals in each non-dominant layer, and selecting the individuals according to the non-dominant relationship and the crowding degree of the individuals to form a new parent population;
and the control unit is used for inputting a new parent population into the second generation unit, controlling the second generation unit and the third generation unit to operate again until the maximum iteration times are met, and stopping calculation to obtain the optimal values of the phase shift angle and the total number of harmonics.
The embodiment of the present invention is an embodiment of an apparatus based on the same inventive concept as the embodiment of the method, and therefore, for specific technical details and corresponding technical effects, please refer to the embodiment of the method, which is not described herein again.
An embodiment of the present invention further provides an electronic device, as shown in fig. 5, the electronic device may include a processor 51 and a memory 52, where the processor 51 and the memory 52 may be communicatively connected to each other through a bus or in another manner, and fig. 5 takes the example of connection through a bus as an example.
The processor 51 may be a Central Processing Unit (CPU). The Processor 51 may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory 52, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the efficiency optimization method for a dual active bridge in the embodiment of the present invention (for example, the switching function establishing module 401, the harmonic model establishing module 402, the optimizing module 403, and the obtaining module 404 shown in fig. 4). The processor 51 executes various functional applications and data processing of the processor by running non-transitory software programs, instructions and modules stored in the memory 52, that is, implements the efficiency optimization method of the dual active bridge in the above method embodiment.
The memory 52 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor 51, and the like. Further, the memory 52 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory 52 may optionally include memory located remotely from the processor 51, and these remote memories may be connected to the processor 51 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The one or more modules are stored in the memory 52 and when executed by the processor 51 perform a method for efficiency optimization of a dual active bridge as in the above-described method embodiments.
The specific details of the electronic device may be understood by referring to the corresponding related descriptions and effects in the above method embodiments, and are not described herein again.
Accordingly, an embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium is used to store a computer program, and when the computer program is executed by a processor, the processes of the above-mentioned embodiment of the efficiency optimization method for a dual active bridge are implemented, and the same technical effects can be achieved, and in order to avoid repetition, details are not repeated here.
Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the system embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and reference may be made to the partial description of the method embodiment for relevant points.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. A method for optimizing efficiency of a dual active axle, the method comprising:
establishing a fourier form based switching function that is a function of the total number of harmonics and the phase shift angle;
establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by utilizing the switch function based on the Fourier form;
optimizing the objective function based on preset constraint conditions to obtain an optimal value of the total number of the harmonics and an optimal value of the phase shift angle, so that the inductance current of the inductance current dynamic time domain harmonic model is minimum and the capacitance current of the capacitance current dynamic time domain harmonic model is minimum;
and acquiring the minimum inductance current and the minimum capacitance current.
2. The method of claim 1, wherein the constraints comprise at least one of: the output power is constant, the calculation time does not exceed the maximum allowable value, and the total number of harmonics is an integer.
3. The method of claim 2, wherein, in the case that the constraint comprises the output power being constant, the method further comprises:
establishing a relation function between the switch state and each output voltage;
using the fourier-form based switching function and the relationship function, a function of the output power in harmonic form is established.
4. The method of claim 1, wherein the establishing an inductor current dynamic time-domain harmonic model and a capacitor current dynamic time-domain harmonic model using the fourier-form based switching function comprises:
establishing a dynamic time domain expression of the double active bridges by using the Fourier form-based switching function expression;
and deducing a time domain expression of the inductive current and a time domain expression of the capacitive current by using the dynamic time domain expression of the double driving bridges, wherein the time domain expression of the inductive current is used as the dynamic time domain harmonic model of the inductive current, and the time domain expression of the capacitive current is used as the dynamic time domain harmonic model of the capacitive current.
5. The method of claim 4, wherein deriving the time domain representation of the inductor current and the time domain representation of the capacitor current using the dynamic time domain representation of the dual active bridge comprises:
converting the dynamic time domain expression of the double driving bridges into a phase domain expression of the double driving bridges;
deriving a phase domain expression of the inductive current based on the phase domain expression of the double active bridges;
converting the phase domain expression of the inductive current into a time domain expression of the inductive current;
and deriving a time domain expression of the capacitance current based on the time domain expression of the inductance current.
6. The method of claim 4, wherein the establishing a dynamic time domain expression of the dual active bridge using the Fourier-based form of the switching function expression comprises:
establishing a relation function between the switch state and each output voltage;
and establishing a dynamic time domain expression of the double active bridges by using the relation function and the Fourier form-based switching function expression.
7. The method of claim 1, wherein the optimizing the objective function based on the preset constraint condition to obtain the optimal value of the total number of harmonics and the optimal value of the phase shift angle comprises:
s201: randomly generating an initial population with the size of N as a parent population;
s202: after the parent population is subjected to non-dominated sorting, obtaining a first generation offspring population through selection, crossing and mutation operations of a genetic algorithm; n is a positive integer;
s203: from the second generation, merging the parent population and the offspring population into a sorted population with the size of 2N, performing rapid non-dominated sorting, simultaneously performing crowding calculation on the individuals in each non-dominated layer, and selecting the individuals according to the non-dominated relation and the crowding of the individuals to form a new parent population;
s204: and repeating the steps S202 and S203 for the new parent population until the maximum iteration times are met, and stopping calculation to obtain the optimal values of the phase shift angle and the total number of harmonics.
8. An efficiency optimization device for a dual drive axle, comprising:
a switching function establishing module for establishing a Fourier form based switching function, the Fourier form based switching function being a function of the total number of harmonics and a phase shift angle;
the harmonic model establishing module is used for establishing an inductance current dynamic time domain harmonic model and a capacitance current dynamic time domain harmonic model as target functions by utilizing the switch function based on the Fourier form;
the optimization module is used for optimizing the objective function based on a preset constraint condition to obtain an optimal value of the total number of the harmonics and an optimal value of the phase shift angle, so that the inductance current of the inductance current dynamic time domain harmonic model is minimum and the capacitance current of the capacitance current dynamic time domain harmonic model is minimum;
and the obtaining module is used for obtaining the minimum inductance current and the minimum capacitance current.
9. An electronic device, comprising:
a memory and a processor, the memory and the processor being communicatively connected to each other, the memory being configured to store a computer program, which when executed by the processor, implements the method for efficiency optimization of a dual active bridge as claimed in any one of claims 1 to 7.
10. A computer-readable storage medium for storing a computer program which, when executed by a processor, implements the method for efficiency optimization of a dual active bridge of any one of claims 1 to 7.
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