CN111027009A - SHEPWM equation set solving method based on genetic algorithm - Google Patents
SHEPWM equation set solving method based on genetic algorithm Download PDFInfo
- Publication number
- CN111027009A CN111027009A CN201911287091.0A CN201911287091A CN111027009A CN 111027009 A CN111027009 A CN 111027009A CN 201911287091 A CN201911287091 A CN 201911287091A CN 111027009 A CN111027009 A CN 111027009A
- Authority
- CN
- China
- Prior art keywords
- equation
- genetic algorithm
- modulation depth
- solving
- shepwm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
- G06F17/12—Simultaneous equations, e.g. systems of linear equations
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
- G06N3/00—Computing arrangements based on biological models
- G06N3/12—Computing arrangements based on biological models using genetic models
- G06N3/126—Evolutionary algorithms, e.g. genetic algorithms or genetic programming
Abstract
The invention discloses a SHEPWM equation system solving method based on a genetic algorithm, belonging to algorithm optimization of pulse output in motor control, and the method comprises the following steps: setting an objective function and boundary conditions of an output equation of the inverter voltage; when the modulation depth M is zero, solving an output equation of the inverter voltage by using a genetic algorithm to obtain values of three different angles of the inverter voltage when the modulation depth M is zero; when the modulation depth M is not zero, the solution of the genetic algorithm to the output equation of the inverter voltage is set as an initial value, iteration is carried out by using a numerical iteration method to obtain the solution of an equation set under the current M value, and the values of the inverter voltage at three different angles when the M is not zero are obtained.
Description
Technical Field
The invention relates to algorithm optimization of pulse output in motor control, in particular to a SHEPWM equation set solving method based on a genetic algorithm.
Background
The specific harmonic elimination equation set of the SHEPWM technology is a nonlinear transcendental equation, the difficulty exists in selecting an initial value, the equation solving difficulty is complex, the convergence effect is poor, the main frequency speed of a microprocessor is low, most SHEPWM at present mostly adopts a table look-up method to generate PWM waveforms to control a motor, the calculated switching angle is stored in a program by using a (1) offline method, meanwhile, the voltage which is expected to be output is analyzed, the switching angle with an approximate angle result is calculated and found, and the switching state of the IGBT is carried out by using the switching angle, the voltage output by the method is not continuous, meanwhile, the storage space of the program is enlarged along with the increase of the precision, and the flexibility and the real-time performance of the algorithm are deteriorated; (2) the numerical method is the most common method for solving the transcendental equation set, the iterative convergence of the equations is ensured by selecting proper initial values, when the initial values are different, the obtained switch angle tracks are also different, the calculation speed is high, and the numerical precision is high. However, the numerical iteration method has high calculation speed and high precision, but has poor convergence and difficult initial value calculation, and a proper initial value must be selected to obtain the solution of the SHEPWM equation set, so that the solution range of the domain M cannot be obtained by full modulation, and when M is equal to 0 or more than 0 and 9, narrow pulses are easily formed; (3) in the existing control algorithm, a genetic algorithm follows an evolutionary theory, global optimization searching is carried out according to natural selection and biological rules of genes, a SHEPWM equation set is solved by utilizing the global searching function of the method so as to solve the switching angle of the inverter under the full-modulation domain, the calculation speed is low, and the convergence is unstable.
Disclosure of Invention
According to the problems existing in the prior art, the invention discloses a SHEPWM equation system solving method based on a genetic algorithm, which comprises the following steps:
s1, setting an objective function and boundary conditions of an output equation of the inverter voltage;
s2, when the modulation depth M is zero, solving an output equation of the inverter voltage by using a genetic algorithm to obtain values of different angles of the output pulse of the inverter when the M is zero;
and when the modulation depth M is not zero, setting the solution of the genetic algorithm to the output equation of the inverter voltage as an initial value, iterating by using a numerical iteration method to obtain the solution of an equation set under the current M value, and obtaining values of different angles of the output pulse of the inverter when the M is not zero.
Further: the output equation of the inverter voltage is as follows:
wherein: u shapedIndicating the dc bus voltage, M modulation depth, α switching angle, N switching angle number.
Further: the solution found for the output equation of the inverter voltage is verified in the following way:
s1: according to the smoothness of the switch angle track, the solution of a previous group of equation sets is used as an initial value of a next equation set, and the solutions are sequentially solved to obtain the track of the switch angle under the full modulation domain;
s2: and simulating a curve equation of the modulation depth M through the angle obtained by S1, fitting a curve by using a third-party software cftool kit, and performing a unitary quadratic function to obtain a switching angle curve under the full modulation domain (the function power is less than or equal to 2, and solutions of a 7-frequency division, a 5-frequency division and a 3-frequency division equation (1) are sequentially calculated according to the method, wherein the method is used for replacing a table look-up method.
Further, the output equation of the inverter voltage is solved by using a genetic algorithm as follows:
s1, setting the modulation depth M and the number N of the switch angles in the third software, and setting the boundary conditions of the switch angles;
s2, generating a coordination elimination equation set and a fitness function under the condition of the number N of the current switching angles;
s3, calculating the fitness;
and S4, outputting an optimal initial value through a genetic algorithm.
Further, iteration is performed on the initial value by using a numerical iteration method through third-party software, and the solution process of the equation set under different M values is obtained as follows:
s1, initializing the number N of the switch angles, the modulation depth M and the step length, and simultaneously determining the boundary value of the switch angles;
s2, solving the equation set under the current N value and setting function parameter values;
s3, calling a function to solve the equation set;
and S4, calculating the switching angle of the modulation depth M between 0 and 1.
Due to the adoption of the technical scheme, the SHEPWM equation system solving method based on the genetic algorithm provided by the invention utilizes the global solution searching characteristic of the genetic algorithm and the rapid convergence characteristic of a numerical iteration method to calculate the initial value of the angle, utilizes the cftool kit to fit the angle curve, simplifies the table look-up method in the original method, and simultaneously completes the angle trajectory optimization method so as to reduce the output harmonic wave.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a lower 7-fold tuning to depth curve according to the present invention;
fig. 2 is a lower 5 minute tone-to-depth curve of the present invention.
Detailed Description
In order to make the technical solutions and advantages of the present invention clearer, the following describes the technical solutions in the embodiments of the present invention clearly and completely with reference to the drawings in the embodiments of the present invention:
a SHEPWM equation system solving method based on a genetic algorithm comprises the following steps:
s1, setting an output equation of the inverter voltage, simultaneously combining a GA tool box of MATLAB, determining internal parameters, and then combining the characteristics of a SHEPWM equation set to construct an objective function and boundary conditions;
s2, when the modulation depth M is zero, solving an output equation of the inverter voltage by using a genetic algorithm to obtain values of different angles of the output pulse of the inverter when the modulation depth M is zero;
and when the modulation depth M is not zero, setting the solution of the genetic algorithm to the output equation of the inverter voltage as an initial value, iterating by using a numerical iteration method to obtain solutions of equation sets under different M values, and obtaining values of different angles of the output pulse of the inverter when the M is not zero.
Further: the output equation of the inverter voltage is as follows:
wherein: u shapedRepresenting the dc bus voltage, M modulation depth, α representing the switching angle, N representing the number of switching angles,
meanwhile, combining a GA tool box of MATLAB, establishing a fitness function by combining the characteristics of a SHEPWM equation set after determining internal parameters, and simplifying the formula (1) into a formula (2) by utilizing the minimization problem of the fitness function;
ground: the solution found for the output equation of the inverter voltage is verified in the following way:
s1: according to the smoothness of the switch angle track, the solution of a previous group of equation sets is used as an initial value of a next equation set, and the solutions are sequentially solved to obtain the track of the switch angle under the full modulation domain;
s2: simulating a curve equation of modulation depth M through the angle obtained by S1, fitting a curve by using a third-party software cftool kit, performing a unitary quadratic function to obtain a switching angle curve (the function power is less than or equal to 2) under the full modulation domain, and sequentially calculating the solutions of a 7-frequency division, 5-frequency division and 3-frequency division equation (1) according to the method, wherein the method is used for replacing a table look-up method, and FIG. 1 is a depth curve adjusted by the 7-frequency division under the method; fig. 2 is a lower 5 minute tone-to-depth curve of the present invention.
Further, the output equation of the inverter voltage is solved by using a genetic algorithm as follows:
s1, setting the modulation depth MM and the number N of the switch angles in MATLAB software, and simultaneously setting the boundary conditions of the switch angles;
s2, generating a coordination elimination equation set and a fitness function under the condition of the number N of the current switching angles;
s3, calculating the fitness to obtain an initial value with the best convergence;
and S4, outputting the optimal angle value through a genetic algorithm.
Further, solving the SHEPWM equation by using a nonlinear equation system solving function fsolve in matlab, and iterating by using a numerical iteration method to obtain the equation system under the current M value by the following solution process:
s1, initializing the number N of the switch angles, the modulation depth M and the step length, and simultaneously determining the boundary value of the switch angles;
s2, solving the equation set under the current N value and setting function parameter values;
s3, calling a function to solve the equation set;
and S4, calculating the switching angle of the modulation depth M between 0 and 1.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (5)
1. A SHEPWM equation system solving method based on genetic algorithm is characterized in that: the method comprises the following steps:
s1: setting an objective function and boundary conditions of an output equation of the inverter voltage;
s2: when the modulation depth M is zero, solving an output equation of the inverter voltage by using a genetic algorithm to obtain values of different angles of the output pulse of the inverter when the modulation depth M is zero;
and when the modulation depth M is not zero, setting the solution of the genetic algorithm to the output equation of the inverter voltage as an initial value, iterating by using a numerical iteration method to obtain the solution of an equation set under the current M value, and obtaining values of different angles of the output pulse of the inverter when the M is not zero.
2. The method of solving the SHEPWM system of equations based on genetic algorithm as claimed in claim 1, further characterized by: the output equation of the inverter voltage is as follows:
wherein: u shapedIndicating the dc bus voltage, M the modulation depth, α the switching angle, and N the number of switching angles.
3. The method of solving the SHEPWM system of equations based on genetic algorithm as claimed in claim 1, further characterized by: the solution found for the output equation of the inverter voltage is verified in the following way:
s1: according to the smoothness of the switch angle track, the solution of a previous group of equation sets is used as an initial value of a next equation set, and the solutions are sequentially solved to obtain the track of the switch angle under the full modulation domain;
s2: and (3) simulating a curve equation of the modulation depth M, fitting a curve by using a third-party software cftool kit, performing a unitary quadratic function to obtain a switching angle curve under the full modulation domain, and sequentially calculating solutions of a frequency division equation (1) of 7, 5 and 3.
4. The method of solving the SHEPWM system of equations based on genetic algorithm as claimed in claim 1, further characterized by: the output equation of the inverter voltage is solved by using a genetic algorithm as follows:
s1, setting the modulation depth M and the number N of the switch angles in the third software, and setting the boundary conditions of the switch angles;
s2, generating a coordination elimination equation set and a fitness function under the condition of the number N of the current switching angles;
s3, calculating the fitness;
and S4, outputting the optimal angle value.
5. The method of solving the SHEPWM system of equations based on genetic algorithm as claimed in claim 1, further characterized by: iterating the initial value by using a numerical iteration method through third-party software and a third-party software to obtain the solution process of the equation set under different M values as follows:
s1, initializing the number N of the switch angles, the modulation depth M and the step length, and simultaneously determining the boundary value of the switch angles;
s2, solving the equation set under the current N value and setting function parameter values;
s3, calling a function to solve the equation set;
and S4, calculating the switching angle of the modulation depth M between 0 and 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911287091.0A CN111027009A (en) | 2019-12-14 | 2019-12-14 | SHEPWM equation set solving method based on genetic algorithm |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911287091.0A CN111027009A (en) | 2019-12-14 | 2019-12-14 | SHEPWM equation set solving method based on genetic algorithm |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111027009A true CN111027009A (en) | 2020-04-17 |
Family
ID=70209173
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911287091.0A Pending CN111027009A (en) | 2019-12-14 | 2019-12-14 | SHEPWM equation set solving method based on genetic algorithm |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111027009A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070242489A1 (en) * | 2006-04-13 | 2007-10-18 | Tatung Company | Method of designing an RPWM inverter with unwanted harmonic elimination |
| CN104022667A (en) * | 2014-06-19 | 2014-09-03 | 安徽大学 | SHEPWM method for three-level inverter |
| CN104201969A (en) * | 2014-09-29 | 2014-12-10 | 永济新时速电机电器有限责任公司 | Modulating methods for semi-conductor device in diesel locomotive converter |
| CN107425703A (en) * | 2017-06-20 | 2017-12-01 | 株洲中车时代电气股份有限公司 | A kind of computational methods and system of optimal harmonic wave distribution SHEPWM switching angles |
-
2019
- 2019-12-14 CN CN201911287091.0A patent/CN111027009A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070242489A1 (en) * | 2006-04-13 | 2007-10-18 | Tatung Company | Method of designing an RPWM inverter with unwanted harmonic elimination |
| CN104022667A (en) * | 2014-06-19 | 2014-09-03 | 安徽大学 | SHEPWM method for three-level inverter |
| CN104201969A (en) * | 2014-09-29 | 2014-12-10 | 永济新时速电机电器有限责任公司 | Modulating methods for semi-conductor device in diesel locomotive converter |
| CN107425703A (en) * | 2017-06-20 | 2017-12-01 | 株洲中车时代电气股份有限公司 | A kind of computational methods and system of optimal harmonic wave distribution SHEPWM switching angles |
Non-Patent Citations (1)
| Title |
|---|
| 陈建峰: "双极性SHEPWM技术在内燃机车主变流器的应用研究" * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2020177238A1 (en) | Neutral point balance control method and system for three-level converter of full power factor range | |
| CN107425703B (en) | Calculation method and system for optimal harmonic distribution SHEPWM switching angle | |
| CN111222707B (en) | Wind speed prediction method based on time series mutation error correction | |
| CN112187124B (en) | Electric drive system control method and device, vehicle and storage medium | |
| CN110460089B (en) | LCL grid-connected inverter FCS-MPC control method based on multivariable prediction | |
| CN110276437A (en) | Mixing based on Fuch mapping improves grey wolf optimization algorithm | |
| CN104270023B (en) | A kind of harmonic wave of multi-electrical level inverter optimizes modulator approach | |
| Chabni et al. | ANN-based SHEPWM using a harmony search on a new multilevel inverter topology | |
| CN110492821A (en) | Based on the direct flux linkage control method of magneto for being not fixed vector action time | |
| CN117134643A (en) | Four-bridge arm inverter duty ratio optimized voltage prediction control method | |
| CN111027009A (en) | SHEPWM equation set solving method based on genetic algorithm | |
| Rui et al. | Modulated model-free predictive current control for voltage source inverters with stagnation elimination and sampling disturbance suppression | |
| CN105678049A (en) | End effect suppression method based on improved SVR continuation | |
| Bahari et al. | Application of differential evolution to determine the HEPWM angles of a three phase voltage source inverter | |
| CN107317498A (en) | A kind of many level based on dichotomy simplify SVPWM modulation strategies | |
| CN111523635A (en) | Harmonic detection method based on combination of artificial bee colony algorithm and least square method | |
| CN109831108A (en) | A kind of three-level current transformer SVPWM method based on resolution of vectors | |
| CN114725887A (en) | Overcurrent protection method, device, equipment and storage medium | |
| CN110365273B (en) | Method for determining alternative voltage vector set by equally dividing flux linkage circle | |
| CN110334935B (en) | Method and device for evaluating transient stability of grid-connected converter and storage medium | |
| CN108717471B (en) | Modeling method for volt-ampere characteristic of voltage domain oscillation quantum device | |
| CN112531782A (en) | Method for suppressing voltage fluctuation of bus of wind power converter | |
| CN107317377B (en) | Battery-formed component bidirectional AC-DC circuit and control method thereof | |
| CN113411006B (en) | Whale algorithm-based charging and discharging control method for energy storage bidirectional converter in grid-connected mode | |
| CN113630031B (en) | Method for determining single-phase full-bridge inverter SHEPWM switch angle |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |