Switched reluctance linear motor suitable for gravity energy storage system and design method and device thereof

Abstract

The invention discloses a switched reluctance linear motor suitable for a gravity energy storage system and a design method and device of the switched reluctance linear motor. The motor comprises an energy storage block, a non-magnetic conductive frame, a stator, a rotor and two excitation windings. The rotor consists of a rotor yoke part, a rotor pole and a rotor pole shoe; each rotor pole is of a single-peak curve tooth structure, the surface of each rotor pole is arranged to be an arc-shaped face protruding outwards, and the rotor pole shoe is arranged on the tooth tip of each rotor pole. Through a multi-layer multi-objective optimization method, optimization parameters are screened into strong sensitive parameters and weak sensitive parameters and then are optimized respectively, so that the optimal structure of the switched reluctance linear motor is efficiently determined. The linear motor has large enough thrust and high capacity conversion efficiency under the electric and power generation working conditions, mechanical vibration can be reduced through low thrust pulsation achieved through staggered teeth, and the linear motor has the advantages of being large in output force, large in power density, stable in operation, low in maintenance cost and the like; and the method has a good engineering application value in a long-stroke gravity energy storage system.

Description

Technical Field

[0001] The present invention belongs to the field of linear motors, and in particular relates to a switched reluctance linear motor suitable for a gravity energy storage system and a design method and device thereof. Background Art

[0002] The global demand for new energy sources is growing, and large-scale energy storage technology is needed to alleviate the uncertainty of energy supply caused by the grid connection of renewable energy sources to balance electricity supply and demand. Gravity energy storage technology has shown important application prospects with its multiple advantages such as efficient energy conversion and large energy storage capacity, long service life, low degree of degradation, low environmental impact, and economic feasibility. The switched reluctance linear motor has a simple structure, is durable, and has high fault tolerance and reliability. Its secondary structure without permanent magnets and windings reduces the complex mechanical coupling and vulnerable parts inside the motor. It can operate stably for a long time under complex working conditions. It is a drive device that is very suitable for long-stroke vertical motion.

[0003] Traditional switched reluctance linear motors mostly use a double-salient pole structure. Although this design is simple in structure, it is difficult to generate sufficient thrust, and the thrust pulsation is large, which is not conducive to the smooth operation of the system. In order to realize the potential of gravity energy storage systems in terms of performance, efficiency and reliability, it is necessary to determine the specific topology of the switched reluctance linear motor. Summary of the invention

[0004] In view of the problems existing in the above-mentioned technologies, the present invention proposes a switched reluctance linear motor suitable for a gravity energy storage system and a design method and device thereof. The new switched reluctance linear motor designed by the present invention can meet the specific requirements of long stroke and vertical motion, and can take into account both electric and power generation working states under low-speed and high-thrust conditions. At the same time, during long-term operation, especially under load changes, thrust pulsation can be suppressed to maintain stable output performance. The switched reluctance linear motor proposed in the present invention adopts a modular trapezoidal stator and a single-peak curve rotor tooth structure, which can achieve higher thrust output, smoother operation, and efficient energy conversion, and is particularly suitable for gravity energy storage systems.

[0005] The present invention is implemented according to the following technical solutions:

[0006] In a first aspect, the present invention provides a switched reluctance linear motor suitable for a gravity energy storage system, comprising:

[0007] An energy storage block, which is mounted on a vertically arranged slide rail and moves linearly up and down along the slide rail during the charging and discharging process of the linear motor;

[0008] A non-magnetic conductive frame is symmetrically arranged on both sides of the energy storage block in parallel with the slide rail, and the height of the non-magnetic conductive frame is consistent with the well depth;

[0009] The stator adopts a modular block design, and the stators on both sides are fixed on the side elevations of the non-magnetic conductive frames on both sides facing the energy storage block after being offset by a preset distance in the vertical direction, and the stators cover the entire side elevations of the non-magnetic conductive frames;

[0010] The movers are symmetrically mounted on two side elevations of the energy storage block facing the non-magnetic conductive frame, and the movers and the corresponding stators maintain uniform magnetic coupling through the same air gap;

[0011] Two excitation windings, respectively wound on the corresponding movers;

[0012] The mover is composed of a mover yoke, a mover pole and a mover pole shoe; the mover pole adopts a single-peak curved tooth structure, the surface of each mover pole is set as an outwardly protruding arc surface, and the tooth tip of each mover pole is provided with the mover pole shoe.

[0013] In one embodiment, the stator is a yokeless stator, which is composed of a plurality of trapezoidal ferromagnetic blocks arranged from top to bottom and independent of each other, and the air gap between each trapezoidal ferromagnetic block and the mover is consistent.

[0014] In one embodiment, the excitation winding is a full-pitch three-phase winding, which is evenly wound on the mover pole, each phase winding coil surrounds three adjacent mover poles, and the three-phase winding coils are staggered in a manner of staggering one mover pole.

[0015] In a second aspect, the present invention provides a design method for a switched reluctance linear motor suitable for a gravity energy storage system, the method comprising:

[0016] Determine the initial design parameters of the switched reluctance linear motor according to the design index and the power equation, and establish a finite element model of the motor; the design index includes rated power, rated voltage and rated speed;

[0017] According to the requirements of the motor in two different working states, electric and generating, the electric average thrust F is selected. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r Four indicators are used as optimization targets for the design of switched reluctance linear motors;

[0018] Select the stator segment width b from the initial design parameters st , stator waist width b s , stator block height h s , thickness of the movable yoke h my , width of left pole shoe of mover bmtl , width of right pole shoe of mover b mtr , mover tooth width b m , mover pole shoe height h mt Optimizing parameters for a new switched reluctance linear motor;

[0019] Conduct sensitivity analysis on the optimization parameters and divide the design parameters into strong sensitive parameters and weak sensitive parameters;

[0020] Response surface methodology and genetic algorithm are used to optimize the highly sensitive parameters and obtain the optimal values ​​of the highly sensitive parameters;

[0021] Taguchi orthogonal method is used to optimize the weakly sensitive parameters and obtain the optimal values ​​of the weakly sensitive parameters;

[0022] The single parameter scanning method is used to obtain the range of vertical misalignment distance of the stators on both sides;

[0023] In one embodiment, the electric average thrust F avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r The expressions of the four indicators as the optimization targets of the switched reluctance linear motor design are as follows:

[0024]

[0025] Where P is the power generation, m fe is the weight of the motor rotor core, F max and F min They correspond to the maximum and minimum output thrust respectively.

[0026] In one embodiment, the sensitivity analysis of the optimization parameters is performed to divide the design parameters into highly sensitive parameters and weakly sensitive parameters, including:

[0027] The formula for calculating the sensitivity index is:

[0028]

[0029] In the formula, f represents the optimized target response, z i To optimize the parameter variables;

[0030] The comprehensive sensitivity index G(n i ) to measure the significance of each variable, and use the weight coefficient to evaluate each variable; the comprehensive sensitivity index G(n i ) is calculated as:

[0031]

[0032] In the formula, SFavg , S Fρ , S Pρ and S Fr are the sensitivity indices of electric average thrust, electric thrust density, power generation density and power generation thrust pulsation, ω1, ω2, ω3 and ω4 are S Favg , S Fρ , S Pρ and S Fr The weight value satisfies ω1+ω2+ω3+ω4=1;

[0033] Through finite element analysis, single parameter simulation is performed on each parameter, and the sensitivity index and comprehensive sensitivity index of each design variable for the four optimization objectives are calculated;

[0034] According to the comprehensive sensitivity index, the design parameters are divided into strong sensitive parameters and weak sensitive parameters.

[0035] In one embodiment, the use of response surface methodology and genetic algorithm to optimize the strongly sensitive parameters to obtain the optimal value of the strongly sensitive parameters includes:

[0036] The response surface method is used to design and select sample points for constructing the response surface model of various motor performances;

[0037] Through finite element simulation, the motor output performance corresponding to each experimental point is recorded, and the motor simulation results of the sample points are analyzed using Design-Expert software to establish a response surface model of four optimization objectives and three design variables;

[0038] Conduct significance tests on the response surface models of the four optimization objectives;

[0039] The optimal solution set based on four optimization objectives is obtained by using the non-dominated sorting genetic algorithm II;

[0040] From the obtained optimal solution set, the optimal value of the strongly sensitive parameter is determined.

[0041] In one embodiment, the optimization of the weakly sensitive parameters by using the Taguchi orthogonal method to obtain the optimal value of the weakly sensitive parameters includes:

[0042] Determine the appropriate optimization range of low-sensitivity variables based on initial parameters, and use orthogonal tables to determine the horizontal values ​​of design parameters;

[0043] The objective function is introduced to analyze the impact of the change of low-sensitivity parameters of the motor on the four optimization objectives;

[0044] The objective function expression is:

[0045]

[0046] Wherein, α1, α2, α3 and α4 are the weight values ​​of electric average thrust, electric thrust density, power generation density and power generation thrust pulsation, respectively, satisfying α1+α2+α3+α4=1;

[0047] Through finite element analysis, each parameter combination is modeled and solved in turn, the multi-objective function value is calculated, and the level value of each variable that maximizes the multi-objective optimization function value is taken to determine the optimal value of the weakly sensitive parameter.

[0048] In one embodiment, the weight values ​​α1, α2, α3 and α4 of the electric average thrust, the electric thrust density, the power generation power density and the power generation thrust pulsation are all set to 0.25.

[0049] In a third aspect, the present invention provides a design device for a switched reluctance linear motor suitable for a gravity energy storage system, the device comprising:

[0050] The finite element model module of the motor is used to determine the initial design parameters of the switched reluctance linear motor according to the design indicators and the power equation, and to establish the finite element model of the motor; the design indicators include the rated power, the rated voltage and the rated speed;

[0051] The optimization target module is used to select the electric average thrust F according to the requirements of the motor in two different working states: electric and generating. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r Four indicators are used as optimization targets for the design of switched reluctance linear motors;

[0052] The optimization parameter module is used to select the optimization parameters of the new switched reluctance linear motor from the initial design parameters; the optimization parameters include the stator block width b st , stator waist width b s , stator block height h s , thickness of the movable yoke h my , width of left pole shoe of mover b mtl , width of right pole shoe of mover b mtr , mover tooth width b m , mover pole shoe height h mt ;

[0053] Sensitivity classification module, used to perform sensitivity analysis on optimization parameters and classify design parameters into strong sensitive parameters and weak sensitive parameters;

[0054] The optimal value calculation module of the strongly sensitive parameter is used to optimize the strongly sensitive parameter by using the response surface method and the genetic algorithm to obtain the optimal value of the strongly sensitive parameter;

[0055] The optimal value calculation module of the weakly sensitive parameters uses the Taguchi orthogonal method to optimize the weakly sensitive parameters and obtain the optimal values ​​of the weakly sensitive parameters;

[0056] The vertical misalignment distance calculation module uses a single parameter scanning method to obtain the range of the vertical misalignment distance of the stators on both sides.

[0057] Beneficial effects of the present invention:

[0058] (1) The switched reluctance linear motor of the present invention adopts a long secondary and short primary structure, which effectively reduces the material cost and is suitable for long-stroke, vertically running gravity energy storage systems; the single-peak curve tooth structure of the mover significantly improves the inductance change rate, so that the motor can generate greater thrust when the mover is aligned and disengaged from the stator teeth, which is the key to improving the low-speed and high-thrust performance of the motor; the modular segmented stator does not have a traditional yoke core, which reduces costs and iron losses. While ensuring the symmetry of the structure and the stability of the performance, the stator segments fixed on both sides of the frame are offset by a certain distance in the vertical direction. The offset distribution reduces the thrust fluctuations acting on the weight blocks at the same time, thereby smoothing the output thrust, reducing thrust pulsation, and improving the operating stability of the system. The three-phase full-pitch winding shortens the magnetic flux path, further increases the phase inductance, and thus improves the thrust density of the motor.

[0059] (2) The switched reluctance linear motor of the present invention has sufficiently large thrust and high energy conversion efficiency under both electric and power generation conditions. The low thrust pulsation achieved by staggered teeth can reduce mechanical vibration. It has the advantages of large output, high power density, stable operation, and low maintenance cost. It is particularly suitable for long-stroke gravity energy storage systems and has good engineering application value. It can meet the needs of long-stroke, vertically operating gravity energy storage systems and is a new type of switched reluctance linear motor that takes into account both electric and power generation working states.

[0060] (3) The present invention proposes a multi-layer multi-objective optimization method, which selects the optimization parameters into strongly sensitive parameters and weakly sensitive parameters and optimizes them separately to efficiently determine the optimal structure of the switched reluctance linear motor and effectively improve the performance indicators of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings described below are only some embodiments. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0062] In the attached figure: mover 1, stator 2, excitation winding 3, energy storage block 4, non-magnetic conductive frame 5, slide rail 6,

[0063] Figure 1 A schematic diagram of the structure of a switched reluctance linear motor suitable for a gravity energy storage system provided by one embodiment of the present invention;

[0064] Figure 2 It is a schematic diagram of the structure of a switched reluctance linear motor with single-peak curve mover teeth and a segmented stator provided in one embodiment of the present invention;

[0065] Figure 3 A flow chart of a design method for a switched reluctance linear motor suitable for a gravity energy storage system provided by an embodiment of the present invention;

[0066] Figure 4 A response surface model of four optimization objectives provided in one embodiment of the present invention; wherein Figure 4 (a) is the average electric thrust F avg The response surface of Figure 4 (b) is the electric thrust density F ρ The response surface of Figure 4 (c) is the power density P ρ The response surface of Figure 4 (d) is the power generation thrust pulsation F r The response surface of

[0067] Figure 5 is the optimal solution set of the NSGA-II algorithm provided in one embodiment of the present invention; wherein Figure 5 (a) is based on F avg 、F ρ 、F r The optimal solution set of Figure 5 (b) is based on F avg 、F r , P ρ The optimal solution set of ;

[0068] Figure 6 A multi-objective function variation curve of the optimization variable level value provided in one embodiment of the present invention;

[0069] Figure 7 A comparison diagram of thrust pulsation before and after the stators on both sides are misaligned provided in one embodiment of the present invention; wherein Figure 7 (a) is the comparison of the electric thrust waveform generated by the entire energy storage block before and after the dislocation in the electric state. Figure 7 (b) Comparison of the power generation thrust waveforms generated by the entire energy storage block before and after the dislocation in the power generation state;

[0070] Figure 8 A static electromagnetic force curve diagram of a switched reluctance linear motor applicable to a gravity energy storage system provided in one embodiment of the present invention;

[0071] Fig. 9An inductance curve diagram of a switched reluctance linear motor suitable for a gravity energy storage system provided in one embodiment of the present invention;

[0072] Fig.10 The schematic diagram of the flat-tooth switched reluctance linear motor structure for comparison;

[0073] Fig.11 The figure is a comparison diagram of the phase inductance characteristics of the switched reluctance linear motor of the present invention and the traditional switched reluctance linear motor when the current is 2A and 3A respectively. Fig.11 (a) is a comparison diagram of phase inductance characteristics when the current is 2A. Fig.11 (b) is a comparison diagram of phase inductance characteristics when the current is 3A.

[0074] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0076] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0077] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] like Figure 1 , Figure 2 As shown, the present invention provides a switched reluctance linear motor suitable for a gravity energy storage system, comprising a mover 1, a stator 2, an excitation winding 3, an energy storage block 4, a non-magnetic conductive frame 5, and a slide rail 6.

[0079] The energy storage block 4 is mounted on a vertically arranged slide rail 6, and moves up and down along the slide rail 6 during the charging and discharging process of the linear motor; in the charging stage, the linear motor obtains electrical energy from the power grid, pushes the energy storage block 4 upward along the slide rail 6, and converts the electrical energy into potential energy for storage; in the power generation stage, the energy storage block 4 falls downward along the slide rail 6, converts the stored potential energy into electrical energy, and feeds it back to the power grid through the converter.

[0080] The non-magnetic conductive frame 5 is symmetrically arranged on both sides of the energy storage block 4 in parallel with the slide rail 6, and the height of the non-magnetic conductive frame 5 is consistent with the well depth to meet the operation requirements of the long-stroke gravity energy storage system.

[0081] The stator 2 adopts a modular block design. In order to reduce thrust pulsation, while ensuring the symmetry of the structure and the stability of the performance, the stators 2 on both sides are fixed to the non-magnetic conductive frames 5 on both sides on the side facades facing the energy storage block 4 after being offset by a preset distance in the vertical direction, and the stator 2 covers the entire side facade of the non-magnetic conductive frame 5.

[0082] The mover 1 is symmetrically mounted on two side elevations of the energy storage block 4 facing the non-magnetic conductive frame 5, and the mover 1 maintains uniform magnetic coupling with the corresponding stator 2 through the same air gap.

[0083] The two excitation windings 3 are respectively wound on the corresponding movers 1 , which effectively reduces the volume and weight of the excitation windings 3 .

[0084] The above-mentioned mover and excitation winding are further described below.

[0085] Continue to refer to Figure 1 , Figure 2 As shown, the mover 1 is composed of a mover yoke 103, a mover pole 101 and a mover pole shoe 102; the mover 1 pole adopts a single-peak curve structure, each mover tooth surface is set as an outwardly protruding arc surface, and the tooth tip of each mover tooth is provided with a mover pole shoe 102; the single-peak curve mover tooth design makes the inductance change rate significantly increased when the mover and the stator are gradually aligned or separated, thereby generating a larger thrust in a smaller displacement change. The arc structure makes the inductance change process smoother and the thrust output more stable, ensuring a smoother operation under motoring and power generation conditions.

[0086] Continue to refer to Figure 1 , Figure 2 As shown, the excitation winding 3 is a full-pitch three-phase winding, which is evenly wound on the mover pole 101. Each phase winding coil surrounds three adjacent mover poles 101, and the three-phase winding coils are staggered with one mover pole 101, forming a compact and effective magnetic flux circuit, with a shorter magnetic flux path and a larger phase inductance, further increasing the thrust density of the motor.

[0087] The above-mentioned stator is further described below.

[0088] Continue to refer to Figure 1 As shown, the stator 2 adopts a modular block design, which is composed of multiple trapezoidal ferromagnetic blocks arranged from top to bottom and independent of each other. This modular design without yoke is conducive to the maintenance and replacement of the stator, effectively reducing the manufacturing cost and system complexity. In order to reduce thrust pulsation, while ensuring the symmetry of the structure and the stability of the performance, the stators 2 on both sides are offset by a certain distance in the vertical direction.

[0089] In one embodiment, the present invention proposes a design method for a switched reluctance linear motor suitable for a gravity energy storage system, such as Figure 3 As shown, the specific steps of this method are as follows:

[0090] Step S100: determining initial design parameters of the switched reluctance linear motor according to design indicators and a power equation, and establishing a finite element model of the motor.

[0091] Design indicators include rated power, rated voltage and rated speed.

[0092] In order to simulate the reasonable operating speed of the low-speed and long-stroke gravity energy storage system, the rated speed of the linear motor is set to 0.5m / s, which can smoothly realize the lifting and lowering movement of the weight block during the charging and discharging process. The rated power of the motor is set to 30W and the rated voltage is 24V. The initial design parameters of the switched reluctance linear motor are shown in Table 1.

[0093] Table 1 Initial design parameters of linear motor

[0094]

[0095] Step S200: Select the average electric thrust F according to the requirements of the motor in two different working states: electric and generating. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r Four indicators are used as optimization targets for the design of switched reluctance linear motor.

[0096] In order to take into account the requirements of the motor in two different working states: electric and generating, the electric average thrust F is selected. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r The four indicators are used as the optimization targets for the design of switched reluctance linear motors, and the expressions are as follows:

[0097]

[0098] Where P is the power generation, mfe is the weight of the motor rotor core, F max and F min They correspond to the maximum and minimum output thrust respectively.

[0099] Step S300: Selecting optimized parameters of the novel switched reluctance linear motor from the initial design parameters.

[0100] Select stator block width b st , stator waist width b s , stator block height h s , thickness of the movable yoke h my , width of left pole shoe of mover b mtl , width of right pole shoe of mover b mtr , mover tooth width b m , mover pole shoe height h mt These are the main optimization parameters of the switched reluctance linear motor of the present invention.

[0101] Step S400: performing sensitivity analysis on the optimization parameters, and dividing the design parameters into highly sensitive parameters and weakly sensitive parameters.

[0102] In the embodiment of the present application, a sensitivity analysis is performed on the optimization parameters, and the design parameters are divided into strong sensitive parameters and weak sensitive parameters, including:

[0103] Step S410: Set the calculation sensitivity index. The formula for calculating the sensitivity index is:

[0104]

[0105] In the formula, f represents the optimized target response, z i To optimize the parameter variables;

[0106] Step S420: Using the comprehensive sensitivity index G(n i ) is used to measure the significance of each variable, and the weight coefficient is used to evaluate each variable.

[0107] Specifically, in order to comprehensively consider the four optimization objectives to achieve the optimization of comprehensive performance, the comprehensive sensitivity index G(n i ) is used to measure the significance of each variable, and the weight coefficient is used to evaluate each variable. The comprehensive sensitivity index G(n i ) is calculated as follows:

[0108]

[0109] In the formula, S Favg , S Fρ , S Pρ and S Frare the sensitivity indices of electric average thrust, electric thrust density, power generation density and power generation thrust pulsation, ω1, ω2, ω3 and ω4 are S Favg , S Fρ ,,S Pρ and S Fr The weight value satisfies ω1+ω2+ω3+ω4=1.

[0110] In order to optimize the comprehensive performance of the motor in both the motoring and generating states, in this example, the values ​​of the four weight factors are all set to 0.25.

[0111] Step S430: Perform single parameter simulation on each parameter through finite element analysis to calculate the sensitivity index and comprehensive sensitivity index of each design variable for the four optimization objectives. The results are shown in Table 2.

[0112] Table 2 Sensitivity index of optimization parameters

[0113]

[0114] Step S440: Divide the design parameters into strong sensitive parameters and weak sensitive parameters according to the comprehensive sensitivity index to reduce the number of variables and improve the optimization efficiency.

[0115] The three variables b whose comprehensive sensitivity is greater than 0.5 st , b mtl , b m The remaining five design variables b s 、h s 、h my , b mtr 、h mt The comprehensive sensitivity of all variables was less than 0.5, and they were determined to be low-sensitivity variables.

[0116] Step S500: Optimizing the highly sensitive parameters using the response surface method and the genetic algorithm to obtain the optimal values ​​of the highly sensitive parameters.

[0117] In the embodiment of the present application, the response surface method and genetic algorithm are used to optimize the highly sensitive parameters to obtain the optimal values ​​of the highly sensitive parameters, including:

[0118] Step S510: using Box-Behnken design (BBD) to select sample points for constructing a response surface model of various motor performances.

[0119] Specifically, the BBD method takes three levels for each strongly sensitive variable, coded as -1, 0 and +1. Among them, 0 is the center point, +1 and -1 are the corresponding high and low values. The BBD method only requires 17 experimental calculations, while the three-level full factorial design requires 3 3=27 experimental calculations, and the level values ​​of each variable are listed in Table 3.

[0120] Table 3 BBD level values ​​of optimization variables

[0121]

[0122]

[0123] Step S520: Through finite element simulation, the motor output performance corresponding to each experimental point is recorded, and the motor simulation results of the sample points are analyzed using Design-Expert software, and a response surface model of four optimization objectives and three design variables is established, such as Figure 4 shown.

[0124] Three highly sensitive variables b st , b mtl , b m The average electric thrust F avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r The response surface models all have high gradients, which verifies the high sensitivity of the three parameters.

[0125] Step S530: performing a significance test on the response surface model of the four optimization objectives.

[0126] Specifically, the multivariate correlation coefficient R 2 Indicates the degree of approximation of the model to the actual performance of the motor, R 2 The closer the value is to 1, the better the model fits the motor performance. R of the four response surface models 2 The values ​​of are 0.9994, 0.9998, 0.9981 and 0.9751, respectively, all of which are greater than 0.97, indicating that the response surface models have good fit.

[0127] Step S540: using the non-dominated sorting genetic algorithm II to obtain an optimal solution set based on four optimization objectives.

[0128] The optimal solution set is Figure 5 As shown. In order to comprehensively consider the four optimization objectives and better balance the comprehensive performance of the linear motor in the two states of motoring and generating, the non-dominated sorting genetic algorithm II (NSGA-II) is applied to the obtained response surface model to obtain the optimal solution set based on the four optimization objectives. The population size of the NSGA-II algorithm is set to 100, the maximum number of iterations is set to 100, and the entire optimization process is completed in 5.2 seconds.

[0129] Step S550: Determine the optimal value of the strongly sensitive parameter from the obtained optimal solution set.

[0130] Specifically, several optimization points with better performance are selected from the optimal solution set, and the performance of these optimization points is compared in detail through finite element analysis. The performance of these three optimization points is listed in Table 4.

[0131] Table 4 BBD level values ​​of optimization variables

[0132]

[0133] Although the electric average thrust and electric thrust density of Scheme 1 are the highest, its power generation density and power generation thrust pulsation are relatively low. The overall performance of the motors of Schemes 2 and 3 is better, but the electric thrust density and power generation density are considered to be more important considerations. Therefore, the present invention selects Scheme 3 as the final design scheme. That is, the value of the strong sensitivity variable is b st 18.1mm, b mtl 5.5mm, b m It is 4.4mm.

[0134] Step S600: optimizing the weakly sensitive parameters by using the Taguchi orthogonal method to obtain the optimal values ​​of the weakly sensitive parameters.

[0135] In the embodiment of the present application, the Taguchi orthogonal method is used to optimize the weakly sensitive parameters to obtain the optimal values ​​of the weakly sensitive parameters, including:

[0136] Step S610: Determine the appropriate optimization range of the low-sensitivity variable according to the initial parameters, and use the orthogonal table to determine the level value of the optimization parameter.

[0137] In the orthogonal experiment, a 5-factor 4-level orthogonal table is selected, which only requires 16 experiments. The number of experiments is greatly reduced, which improves the optimization efficiency. The level values ​​of the optimization variables are set as shown in Table 5.

[0138] Table 5 Orthogonal level values ​​of optimization variables

[0139]

[0140] Step S620: In order to analyze the impact of the low-sensitivity parameter changes on the four optimization objectives, an objective function is introduced to analyze the impact of the low-sensitivity parameter changes of the motor on the four optimization objectives.

[0141] Furthermore, the objective function expression is:

[0142]

[0143] Wherein, α1, α2, α3 and α4 are the weight values ​​of the electric average thrust, electric thrust density, power generation power density and power generation thrust pulsation, respectively, satisfying α1+α2+α3+α4=1.

[0144] Step S630: Model and solve each parameter combination in turn through finite element analysis to calculate the multi-objective function value F obj , take the level value of each variable that maximizes the value of the multi-objective optimization function as the optimal value of the weakly sensitive parameter.

[0145] Specifically, in this example, the values ​​of the four weight factors are all set to 0.25. The 16 parameter combinations are modeled and solved in turn to obtain the mean and extreme value of the optimization target under each variable, and the multi-objective function value of each weakly sensitive variable can be calculated. Figure 6 The influence of the level value of each design variable in the five factors of ABCDE on the multi-objective function is intuitively demonstrated.

[0146] Select the level value of each variable that maximizes the value of the multi-objective optimization function. When the structural parameter combination is A2B2C2D3E2, the performance is optimal, that is, b mtr , b s 、h s 、h mt 、h my The values ​​are 5.2mm, 5.0mm, 5.0mm, 2.1mm and 5.6mm respectively.

[0147] Step S700: using a single parameter scanning method to obtain a range of vertical misalignment distances of the stators on both sides.

[0148] Since there is no magnetic field coupling phenomenon between the movers installed on both sides of the energy storage block, that is, the magnetic fields generated by the movers on both sides do not interfere with each other, and their respective magnetic circuits are independent, the vertical distance h between the stators on both sides is ss Using the single parameter scanning method, we get h ss The range is 3.3-3.7mm.

[0149] Further, h ss The optimal value is 3.5mm, that is, the stator on one side is offset by 3.5mm in the vertical direction from the stator on the other side. The thrust waveform generated by the entire energy storage block before and after the offset is compared. Figure 7 shown.

[0150] In an optional embodiment, the method further includes: performing finite element modeling analysis on the optimal size of the motor to evaluate whether its performance meets the design requirements.

[0151] The initial design and the optimized design were compared and verified by finite element simulation. Table 6 gives the specific dimensions and performance comparison.

[0152] Table 6 Comparison of motor performance before and after optimization

[0153]

[0154] The average thrust and thrust density of the optimized switched reluctance linear motor in the electric state are increased by 13.7% and 60.8% respectively, the power density in the power generation state is increased by 52.6%, and the thrust pulsation is reduced by 80.5%. Compared with the initial design, the performance is greatly improved, which verifies the effectiveness of the optimization method described in the present invention.

[0155] On the other hand, the static characteristics of the optimized motor were analyzed. Figure 8 The static electromagnetic force curve is given when the current increases from 1A to 6A. The electromagnetic force is zero when the mover moves to the aligned position, and the magnetic resistance is minimum at this time. Under different current values, the static electromagnetic force changes with the position of the mover in the same trend, and as the current increases, the static electromagnetic force also increases accordingly. Fig. 9 The inductance curve of the B-phase winding when the current increases from 2A to 6A is given. In the misaligned position, the air gap is large, the magnetic resistance is large, and the inductance is small; in the aligned position, the air gap is small, the magnetic resistance is small, and the inductance reaches the maximum value. The inductance under different currents is almost equal in the misaligned position, and both reach the maximum value in the aligned position, and the inductance gradually decreases as the current increases. When the current is 2A, the maximum inductance of the motor reaches 120.9mH, while the minimum inductance is 40.7mH, and the maximum-minimum inductance ratio reaches 2.97.

[0156] To further illustrate the advantages of the novel switched reluctance linear motor proposed in the present invention, the novel switched reluctance linear motor is compared with a segmented stator switched reluctance linear motor using a flat gear rotor. The structural schematic diagram of the latter is shown in FIG. Fig.10 As shown. The structural parameters of the single-peak curve rotor teeth and the flat-tooth linear motor are basically the same, but because the surface of the single-peak curve rotor teeth is arc-shaped, the air gap thickness at the vertex of the single-peak curve rotor teeth is 0.4mm, and the pole shoe thickness at the tooth tips on both sides of the pole shoe is 0.8mm, resulting in an average air gap thickness of 0.6mm. Therefore, the air gap thickness of the flat-tooth motor is also taken as 0.6mm, that is, the distance between the stator pole and the rotor flat tooth is 0.6mm.

[0157] Fig.11The phase inductance characteristics of the two motors are given when the current is 2A and 3A respectively. The non-aligned inductance of the two motors is not much different, while the aligned inductance of the single-peak curve rotor tooth linear motor is significantly larger, with a larger maximum-to-minimum inductance ratio. At currents of 2A and 3A, the maximum-to-minimum inductance ratio of the single-peak curve rotor tooth linear motor is 2.97 and 2.52 respectively; the maximum-to-minimum inductance ratio of the flat-tooth linear motor is 2.61 and 2.41 respectively. The single-peak curve rotor tooth switched reluctance linear motor can produce a larger inductance change rate under the same conditions, especially under unsaturated current, and can provide greater thrust.

[0158] Through simulation experiments, it is found that the average electric thrust and electric thrust density of the flat-toothed linear motor are 68.560N and 53.389N / kg, respectively, while the average electric thrust and electric thrust density of the single-peak curve rotor gear linear motor are 76.998N and 59.824N / kg, respectively, which are 12.3% and 12.0% higher than the former. The power generation density of the flat-toothed motor is 7.641W / kg, and the power generation density of the single-peak curve rotor gear motor is 10.304W / kg, which is 34.9% higher than the former. The power generation thrust pulsation of the flat-toothed motor is 206.201%, while the power generation thrust pulsation of the single-peak curve rotor gear motor proposed in the present invention is 196.023%. After the stator is properly staggered, the power generation thrust pulsation is reduced to 38.5%.

[0159] Therefore, the single-peak curve rotor tooth block stator switch reluctance linear motor proposed in the present invention is more suitable for low-speed, high-thrust gravity energy storage system than the traditional flat-tooth motor, and can well take into account the system's needs in two different working states: electric and detection. The motor can provide sufficient thrust to overcome the weight of heavy objects and achieve efficient thrust output and energy conversion efficiency in a limited space. At the same time, the low thrust pulsation achieved by staggered teeth can ensure a smooth energy conversion process, reduce mechanical vibration, and improve the overall reliability of the system.

[0160] In one embodiment, a design device for a switched reluctance linear motor suitable for a gravity energy storage system is provided, the device comprising:

[0161] The finite element model module of the motor is used to determine the initial design parameters of the switched reluctance linear motor according to the design indicators and the power equation, and to establish the finite element model of the motor; the design indicators include the rated power, the rated voltage and the rated speed;

[0162] The optimization target module is used to select the electric average thrust F according to the requirements of the motor in two different working states: electric and generating. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation Fr Four indicators are used as optimization targets for the design of switched reluctance linear motors;

[0163] The optimization parameter module is used to select the optimization parameters of the new switched reluctance linear motor from the initial design parameters; the optimization parameters include the stator block width b st , stator waist width b s , stator block height h s , thickness of the movable yoke h my , width of left pole shoe of mover b mtl , width of right pole shoe of mover b mtr , mover tooth width b m , mover pole shoe height h mt ;

[0164] Sensitivity classification module, used to perform sensitivity analysis on optimization parameters and classify design parameters into strong sensitive parameters and weak sensitive parameters;

[0165] The optimal value calculation module of the strongly sensitive parameter is used to optimize the strongly sensitive parameter by using the response surface method and the genetic algorithm to obtain the optimal value of the strongly sensitive parameter;

[0166] The optimal value calculation module of the weakly sensitive parameters uses the Taguchi orthogonal method to optimize the weakly sensitive parameters and obtain the optimal values ​​of the weakly sensitive parameters;

[0167] The vertical misalignment distance calculation module uses a single parameter scanning method to obtain the range of the vertical misalignment distance of the stators on both sides.

[0168] It should be noted that the design device for a switched reluctance linear motor for a gravity energy storage system provided in the above embodiment only uses the division of the above-mentioned functional modules as an example when executing the design method for a switched reluctance linear motor for a gravity energy storage system. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the design device for a switched reluctance linear motor for a gravity energy storage system provided in the above embodiment and the design method embodiment for a switched reluctance linear motor for a gravity energy storage system belong to the same concept. The implementation process thereof is detailed in the design method embodiment for a switched reluctance linear motor for a gravity energy storage system, which will not be repeated here.

[0169] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0170] In addition, those skilled in the art will understand that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments also means being within the scope of protection of the present invention and forming different embodiments. For example, in the above embodiments, those skilled in the art can use them in combination according to the known technical solutions and the technical problems to be solved by this application.

[0171] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A switched reluctance linear motor suitable for a gravity energy storage system, characterized in that: include: An energy storage block, which is mounted on a vertically arranged slide rail and moves linearly up and down along the slide rail during the charging and discharging process of the linear motor; A non-magnetic conductive frame is symmetrically arranged on both sides of the energy storage block in parallel with the slide rail, and the height of the non-magnetic conductive frame is consistent with the well depth; The stator adopts a modular block design, and the stators on both sides are fixed on the side elevations of the non-magnetic conductive frames on both sides facing the energy storage block after being offset by a preset distance in the vertical direction, and the stators cover the entire side elevations of the non-magnetic conductive frames; The movers are symmetrically mounted on two side elevations of the energy storage block facing the non-magnetic conductive frame, and the movers and the corresponding stators maintain uniform magnetic coupling through the same air gap; Two excitation windings, respectively wound on the corresponding movers; The mover is composed of a mover yoke, a mover pole and a mover pole shoe; the mover pole adopts a single-peak curved tooth structure, the surface of each mover pole is set as an outwardly protruding arc surface, and the tooth tip of each mover pole is provided with the mover pole shoe.

2. A switched reluctance linear motor suitable for a gravity energy storage system according to claim 1, characterized in that: The stator is a yoke-free stator, which is composed of a plurality of trapezoidal ferromagnetic blocks which are arranged from top to bottom and are independent of each other, and the air gap between each trapezoidal ferromagnetic block and the mover is consistent.

3. A switched reluctance linear motor suitable for a gravity energy storage system according to claim 2, characterized in that: The excitation winding is a full-pitch three-phase winding, which is evenly wound on the mover poles. Each phase winding coil surrounds three adjacent mover poles, and the three-phase winding coils are staggered in a staggered manner with one mover pole staggered.

4. A design method for a switched reluctance linear motor suitable for a gravity energy storage system based on any one of claims 1 to 3, characterized in that: The method comprises: Determine the initial design parameters of the switched reluctance linear motor according to the design index and the power equation, and establish a finite element model of the motor; the design index includes rated power, rated voltage and rated speed; According to the requirements of the motor in two different working states, electric and generating, the electric average thrust F is selected. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r Four indicators are used as optimization targets for the design of switched reluctance linear motors; Selecting the optimization parameters of the new switched reluctance linear motor from the initial design parameters; the optimization parameters include the stator block width b st , stator waist width b s , stator block height h s , thickness of the movable yoke h my , width of left pole shoe of mover b mtl , width of right pole shoe of mover b mtr , mover tooth width b m , mover pole shoe height h mt ; Conduct sensitivity analysis on the optimization parameters and divide the optimization parameters into strong sensitive parameters and weak sensitive parameters; Response surface methodology and genetic algorithm are used to optimize the highly sensitive parameters and obtain the optimal values ​​of the highly sensitive parameters; Taguchi orthogonal method is used to optimize the weakly sensitive parameters and obtain the optimal values ​​of the weakly sensitive parameters; The single parameter scanning method is used to obtain the range of vertical misalignment distance of the stators on both sides.

5. The design method according to claim 4, characterized in that: Electric average thrust F avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r The expressions of the four indicators as the optimization targets of the switched reluctance linear motor design are as follows: Where P is the power generation, m fe is the weight of the motor rotor core, F max and F min They correspond to the maximum and minimum output thrust respectively.

6. The design method according to claim 4, characterized in that: The sensitivity analysis of the optimization parameters is performed to divide the design parameters into strong sensitive parameters and weak sensitive parameters, including: A formula for calculating the sensitivity index is set; the formula for calculating the sensitivity index is: In the formula, f represents the optimized target response, z i To optimize the parameter variables; The comprehensive sensitivity index G(n i ) to measure the significance of each variable, and use the weight coefficient to evaluate each variable; the comprehensive sensitivity index G(n i ) is calculated as: In the formula, S Favg , S Fρ , S Pρ and S Fr are the sensitivity indices of electric average thrust, electric thrust density, power generation density and power generation thrust pulsation, ω1, ω2, ω3 and ω4 are S Favg , S Fρ , S Pρ and S Fr The weight value satisfies ω1+ω2+ω3+ω4=1; Through finite element analysis, single parameter simulation is performed on each parameter, and the sensitivity index and comprehensive sensitivity index of each design variable for the four optimization objectives are calculated; According to the comprehensive sensitivity index, the design parameters are divided into strong sensitive parameters and weak sensitive parameters.

7. The design method according to claim 5, characterized in that: The method of optimizing the highly sensitive parameters by using the response surface method and the genetic algorithm to obtain the optimal values ​​of the highly sensitive parameters includes: The response surface method is used to design and select sample points for constructing the response surface model of various motor performances; Through finite element simulation, the motor output performance corresponding to each experimental point is recorded, and the motor simulation results of the sample points are analyzed using Design-Expert software to establish a response surface model of four optimization objectives and three design variables; Conduct significance tests on the response surface models of the four optimization objectives; The optimal solution set based on four optimization objectives is obtained by using the non-dominated sorting genetic algorithm II; From the obtained optimal solution set, the optimal value of the strongly sensitive parameter is determined.

8. The design method according to claim 7, characterized in that: The Taguchi orthogonal method is used to optimize the weakly sensitive parameters to obtain the optimal values ​​of the weakly sensitive parameters, including: Taguchi orthogonal method is used to optimize weakly sensitive parameters, appropriate optimization range of low-sensitivity variables is determined according to initial parameters, and horizontal values ​​of design parameters are determined using orthogonal table. The objective function is introduced to analyze the impact of the change of low-sensitivity parameters of the motor on the four optimization objectives; The objective function expression is: Wherein, α1, α2, α3 and α4 are the weight values ​​of electric average thrust, electric thrust density, power generation density and power generation thrust pulsation, respectively, satisfying α1+α2+α3+α4=1; Through finite element analysis, each parameter combination is modeled and solved in turn, the multi-objective function value is calculated, and the level value of each variable that maximizes the multi-objective optimization function value is taken as the optimal value of the weakly sensitive parameter.

9. The design method according to claim 8, characterized in that: The weight values ​​α1, α2, α3 and α4 of the electric average thrust, electric thrust density, power generation power density and power generation thrust pulsation are all set to 0.

25.

10. A design device for a switched reluctance linear motor suitable for a gravity energy storage system based on any one of claims 1 to 3, characterized in that: The device comprises: The finite element model module of the motor is used to determine the initial design parameters of the switched reluctance linear motor according to the design indicators and the power equation, and to establish the finite element model of the motor; the design indicators include the rated power, the rated voltage and the rated speed; The optimization target module is used to select the electric average thrust F according to the requirements of the motor in two different working states: electric and generating. avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r Four indicators are used as optimization targets for the design of switched reluctance linear motors; The optimization parameter module is used to select the optimization parameters of the new switched reluctance linear motor from the initial design parameters; the optimization parameters include the stator block width b st , stator waist width b s , stator block height h s , thickness of the movable yoke h my , width of left pole shoe of mover b mtl , width of right pole shoe of mover b mtr , mover tooth width b m , mover pole shoe height h mt ; Sensitivity classification module, used to perform sensitivity analysis on optimization parameters and classify design parameters into strong sensitive parameters and weak sensitive parameters; The optimal value calculation module of the strongly sensitive parameter is used to optimize the strongly sensitive parameter by using the response surface method and the genetic algorithm to obtain the optimal value of the strongly sensitive parameter; The optimal value calculation module of the weakly sensitive parameters uses the Taguchi orthogonal method to optimize the weakly sensitive parameters and obtain the optimal values ​​of the weakly sensitive parameters; The vertical misalignment distance calculation module uses a single parameter scanning method to obtain the range of the vertical misalignment distance of the stators on both sides.

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