Novel switched reluctance linear motor for gravity energy storage system and optimization design method thereof

Abstract

The invention discloses a novel switched reluctance linear motor for a gravity energy storage system and an optimization design method of the novel switched reluctance linear motor, mover poles of the motor are of a double-peak curve tooth structure, the double-peak curve tooth tip of each mover pole is provided with a mover pole shoe, and the midpoint of the double-peak curve tooth and the vertexes of the mover pole shoes on the two sides are located on the same horizontal line. According to the structure, the maximum inductance value is increased, the high inductance change rate enables the motor to provide larger thrust in an electric state, and potential energy is more effectively converted into electric energy in a power generation state. When the structure of the motor is optimized, an optimization target capable of meeting the requirements of an electric state and a power generation state is selected, the electric state pursues high output thrust for driving a heavy object to ascend, the electric average thrust and the electric thrust density are determined to serve as the electric optimization target, and the power generation state pursues an efficient and stable power generation process. And the power generation power density and the power generation thrust pulsation are determined as power generation optimization targets, so that the optimal comprehensive performance of the motor under the double working conditions is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of linear motors, and in particular relates to a novel switched reluctance linear motor for a gravity energy storage system and an optimization design method 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.

[0004] In addition, during long-term operation, especially when the load changes, how to make the motor produce a higher inductance change rate in both electric and generating conditions, so as to more effectively utilize the input current and generate higher thrust and power generation is also a problem that needs to be solved. Summary of the invention

[0005] In view of the problems existing in the above technologies, the present invention proposes a novel switched reluctance linear motor for a gravity energy storage system and an optimization design method thereof. The present invention utilizes a modular trapezoidal stator and a mover with a double-peaked curved tooth structure to achieve higher thrust, smoother operation and more efficient energy conversion, and can well take into account the dual-operating requirements of the gravity energy storage system for both electric and power generation.

[0006] The present invention is implemented according to the following technical solutions:

[0007] In a first aspect, the present invention provides a novel switched reluctance linear motor for a gravity energy storage system, wherein the switched reluctance linear motor is a long secondary structure, comprising:

[0008] The energy storage block moves up and down along the track during the charging and discharging process of the linear motor;

[0009] The non-magnetic conductive frame is symmetrically arranged on both sides of the energy storage block, and the height of the non-magnetic conductive frame is consistent with the well depth;

[0010] 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;

[0011] 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;

[0012] Two excitation windings, respectively wound on the corresponding movers;

[0013] Among them, the mover is composed of a mover yoke, a mover pole and a mover pole shoe; the mover pole adopts a double-peak curve tooth structure, and the double-peak curve tooth tip of each mover pole is provided with the mover pole shoe, the midpoint of the double-peak curve tooth and the vertices of the mover pole shoes on both sides are on the same horizontal line, and the lengths and heights of the two arcs of the double-peak curve tooth are consistent.

[0014] 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.

[0015] In one embodiment, the excitation winding is a full-pitch three-phase winding, which is evenly wound on the mover pole, each winding coil surrounds three adjacent mover poles, and the three winding coils are staggered in a manner of staggering one mover pole.

[0016] In one embodiment, the stators on both sides are offset by a preset distance in the vertical direction: the stators on the left and right are offset by a quarter of the rotor pole pitch in the vertical direction.

[0017] In a second aspect, the present invention provides an optimization design method for a novel switched reluctance linear motor suitable for a gravity energy storage system, and the specific steps of the method are as follows:

[0018] 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;

[0019] According to the requirements of the motor in two different working states, electric and generating, the optimization target of the switched reluctance linear motor design is selected; in the electric working state, the motor drives the weight to rise, and the electric average thrust F is selected avg and electric thrust density F ρ As the optimization target; in the power generation working state, the weight is lowered to generate electricity, and the power generation power density P is selected ρ and power generation thrust pulsation F r As an optimization goal;

[0020] 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 b mtl , 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;

[0021] Conduct sensitivity analysis on the optimization parameters and divide the design parameters into strong sensitive parameters and weak sensitive parameters;

[0022] Response surface methodology and genetic algorithm are used to optimize the highly sensitive parameters and obtain the optimal values ​​of the highly sensitive parameters;

[0023] Taguchi orthogonal method is used to optimize the weakly sensitive parameters and obtain the optimal values ​​of the weakly sensitive parameters;

[0024] Conduct finite element modeling analysis on the optimal size of the motor to evaluate whether its performance meets the design requirements.

[0025] 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:

[0026]

[0027] 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.

[0028] 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:

[0029] The formula for calculating the sensitivity index is:

[0030]

[0031] In the formula, f represents the optimized target response, z i To optimize the parameter variables;

[0032] 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:

[0033]

[0034] 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 values ​​satisfy ω1+ω2+ω3+ω4=1, and the weight values ​​ω1, ω2, ω3, and ω4 are set to 0.3, 0.2, 0.3, and 0.2 respectively;

[0035] 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;

[0036] According to the sensitivity index and comprehensive sensitivity index of the four optimization objectives, the design parameters are divided into strong sensitive parameters and weak sensitive parameters; the three variables b with large sensitivity index and comprehensive sensitivity greater than 0.6 are 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 0.6, and they were determined to be low-sensitivity variables.

[0037] 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:

[0038] The response surface method is used to design and select sample points for constructing the response surface model of various motor performances;

[0039] 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;

[0040] Conduct significance tests on the response surface models of the four optimization objectives;

[0041] The optimal solution set based on four optimization objectives is obtained by using the non-dominated sorting genetic algorithm II;

[0042] From the obtained optimal solution set, the optimal value of the strongly sensitive parameter is determined.

[0043] 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:

[0044] 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;

[0045] The objective function is introduced to analyze the impact of the change of low-sensitivity parameters of the motor on the four optimization objectives;

[0046] The objective function expression is:

[0047]

[0048] 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.

[0049] Through finite element analysis, each parameter combination is modeled and solved in turn, and the multi-objective function value F is calculated. obj , and take the level value of each variable that maximizes the value of the multi-objective optimization function to determine the optimal value of the weakly sensitive parameter.

[0050] In a third aspect, the present invention provides an optimization design device for a novel switched reluctance linear motor for a gravity energy storage system, the device comprising:

[0051] 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;

[0052] The optimization target module selects the optimization target of the switched reluctance linear motor design according to the requirements of the motor in two different working states: electric and generating. In the electric working state, the motor drives the weight to rise, and the electric average thrust F is selected. avg and electric thrust density F ρ As the optimization target; in the power generation working state, the weight is lowered to generate electricity, and the power generation power density P is selected ρ and power generation thrust pulsation F r As an optimization goal;

[0053] The optimization parameter module selects 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 ;

[0054] Sensitivity classification module, which performs sensitivity analysis on optimization parameters and divides design parameters into strong sensitive parameters and weak sensitive parameters;

[0055] The optimal value calculation module of sensitive parameters uses response surface method and genetic algorithm to optimize the strongly sensitive parameters and obtain the optimal value of the strongly sensitive parameters;

[0056] 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;

[0057] The evaluation module is used to perform finite element modeling analysis on the optimal size of the motor and evaluate whether its performance meets the design requirements.

[0058] Beneficial effects of the present invention:

[0059] (1) The new switched reluctance linear motor of the present invention is suitable for long-stroke, vertically operating gravity energy storage systems, and can meet the dual operating requirements of the gravity energy storage system for both electric and power generation. The mover adopts a double-peak curve tooth structure design, which enables the motor to produce a higher inductance change rate in both electric and power generation conditions, and can more effectively utilize the input current to generate higher thrust and power generation. The modular segmented stator can maintain uniform magnetic coupling with the mover that moves up and down, making the energy conversion process more efficient. The linear motor with a long secondary structure is fully utilized in long strokes, ensuring the stability of the thrust and the continuity of energy conversion. The stators on both sides are staggered by one-quarter of the mover pole pitch in the vertical direction, so that the motors on both sides of the energy storage block generate thrust peaks at different times, reducing the thrust pulsation of the entire system and effectively smoothing the power output.

[0060] (2) The novel switched reluctance linear motor proposed in the present invention can take into account both the motoring and power generation performance of the gravity energy storage system. It is not only suitable for large thrust output in the motoring mode, but also can realize efficient energy conversion to generate electrical energy in the power generation mode. At the same time, the stator staggered tooth design ensures the smooth operation of the system. It has good engineering value in the application of gravity energy storage system. 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 novel switched reluctance linear motor suitable for a gravity energy storage system provided in one embodiment of the present invention;

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

[0065] Figure 3 A flow chart of an optimization design method for a novel switched reluctance linear motor 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 , P ρ The optimal solution set of Figure 5 (b) is based on F r 、F ρ , P ρ The optimal solution set of ;

[0068] Figure 6 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 6 (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 6(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;

[0069] Figure 7 The static electromagnetic force curve and inductance curve of the novel switched reluctance linear motor provided in one embodiment of the present invention are shown in FIG. Figure 7 (a) is the static electromagnetic force curve. Figure 7 (b) is the inductance curve.

[0070] Figure 8 The schematic diagram of the structure of the traditional flat-tooth switched reluctance linear motor for comparison;

[0071] Fig. 9 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. 9 (a) is a comparison diagram of phase inductance characteristics when the current is 2A. Fig. 9 (b) is a comparison diagram of phase inductance characteristics when the current is 3A.

[0072] 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

[0073] 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.

[0074] 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.

[0075] 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.

[0076] like Figure 1 , Figure 2 As shown, the present invention provides a switched reluctance linear motor that takes into account both the motoring and power generation performance of a gravity energy storage system, including a mover 1, a stator 2, an excitation winding 3, an energy storage block 4, and a non-magnetic conductive frame 5.

[0077] The energy storage block 4 is driven by a linear motor to move up and down, completing the two-way flow of energy between the power grid and the gravity energy storage system. In the electric mode, the linear motor generates sufficient thrust through the excitation winding to lift the energy storage block to a high position to achieve potential energy storage; in the power generation mode, the energy storage block moves downward along the track, and the linear motor converts the stored potential energy into electrical energy, and feeds it back to the power grid through the converter. The linear motor used can take into account the electric and power generation performance of the gravity energy storage system. It is not only suitable for large thrust output in the electric mode, but also can achieve efficient energy conversion to generate electrical energy in the power generation mode. The non-magnetic conductive frame 5 is symmetrically arranged on both sides of the energy storage block 4, and the height of the non-magnetic conductive frame 5 is consistent with the well depth.

[0078] 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 on the side facades of the non-magnetic conductive frames 5 on both sides facing the energy storage block 4 after being offset by a preset distance in the vertical direction. The stator 2 covers the entire side facade of the non-magnetic conductive frame 5. The stroke of the linear motor in the electric and power generation processes can be fully utilized to meet the needs of the long-stroke gravity energy storage system.

[0079] The mover 1 is symmetrically mounted on the two side elevations of the energy storage block 4 facing the non-magnetic conductive frame 5, which effectively reduces the volume and weight of the winding compared to the long primary structure; the mover 1 maintains uniform magnetic coupling with the corresponding stator 2 through the same air gap.

[0080] 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 .

[0081] The above-mentioned mover and excitation winding are further described below.

[0082] Continue to refer to Figure 1 , Figure 2As 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 double-peak curve tooth structure, and each double-peak curve tooth tip of the mover pole 101 is provided with a mover pole shoe 102, the midpoint of the double-peak curve tooth and the vertices of the mover pole shoes 102 on both sides are on the same horizontal line, and the length and height of the two arcs of the double-peak curve tooth are consistent, which is conducive to the uniform distribution of the magnetic field and the symmetry of the air gap. Compared with the traditional flat-toothed mover switched reluctance linear motor, its inductance curve can reach the maximum inductance value faster, especially under low saturation working conditions, the maximum inductance value is larger, that is, the mover motor with the double-peak curve tooth structure can produce a higher inductance change rate in the motoring and power generation conditions. Under the same input conditions, the mover motor with a double-peak curve tooth structure can more effectively utilize the input current and generate higher thrust. At the same time, the mover motor with a double-peak curve tooth structure is smoother in the maximum inductance area, and the motor can maintain a more stable inductance value when approaching the peak inductance, thereby better ensuring stable thrust output in actual operation. This inductance characteristic shows that the design of the mover with a double-peak curve tooth structure can enable the motor to better take into account the dual-operating conditions of electric power generation of the gravity energy storage system.

[0083] Continue to refer to Figure 1 , Figure 2 As shown, the excitation winding 3 adopts a three-phase full-pitch winding, which is evenly wound on the mover pole 101, and each phase winding coil surrounds three adjacent mover poles 101, and the three-phase winding coils are staggered by one mover pole 101 to form a compact and efficient magnetic flux loop. The full-pitch winding has a uniform magnetic flux distribution, which can maintain good power output efficiency at low speed, can generate greater thrust in the electric state, and generate higher induced electromotive force in the power generation state to obtain higher power generation power.

[0084] The above-mentioned stator is further described below.

[0085] 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 enables each stator section to maintain uniform magnetic coupling with the mover moving up and down under motoring and power generation conditions, making the energy conversion process more efficient. In order to reduce thrust pulsation, while ensuring the symmetry of the structure and the stability of performance, the stators 2 on both sides are offset by a certain distance in the vertical direction.

[0086] Furthermore, the preset distance of the vertical offset of the stators on both sides is: the stators on the left and right sides are offset by one quarter of the rotor pole pitch in the vertical direction, so that the motors on both sides of the energy storage block generate thrust peaks at different times, thereby reducing the thrust pulsation and power generation fluctuation of the entire system.

[0087] In one embodiment, the present invention proposes an optimization design method for a novel switched reluctance linear motor for a gravity energy storage system, such as Figure 3 As shown, the specific steps of this method are as follows:

[0088] 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.

[0089] Design indicators include rated power, rated voltage and rated speed.

[0090] 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.

[0091] Table 1 Initial design parameters of linear motor

[0092]

[0093] Step S200: According to the requirements of the motor in two different working states, namely, electric and generating, the optimization target of the switched reluctance linear motor design is selected; in the electric working state, the motor drives the weight to rise, and the electric average thrust F is selected. avg and electric thrust density F ρ As the optimization target; in the power generation working state, the weight is lowered to generate electricity, and the power generation power density P is selected ρ and power generation thrust pulsation F r as optimization goal.

[0094] Furthermore, the average electric thrust F avg , Electric thrust density F ρ , power generation density P ρ and power generation thrust pulsation F r The expression is as follows:

[0095]

[0096]

[0097] 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.

[0098] Step S300: Selecting optimized parameters of the novel switched reluctance linear motor from the initial design parameters.

[0099] 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.

[0100] Step S400: performing sensitivity analysis on the optimization parameters, and dividing the design parameters into highly sensitive parameters and weakly sensitive parameters.

[0101] 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:

[0102] Step S410: Set the calculation sensitivity index. The formula for calculating the sensitivity index is:

[0103]

[0104] In the formula, f represents the optimized target response, z i To optimize the parameter variables;

[0105] 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.

[0106] 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:

[0107]

[0108] 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.

[0109] 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 set to 0.3, 0.2, 0.3, and 0.2, respectively.

[0110] 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.

[0111] Table 2 Sensitivity index of optimization parameters

[0112]

[0113] Step S440: The design parameters are divided into strong sensitive parameters and weak sensitive parameters according to the sensitivity indexes and comprehensive sensitivity indexes of the four optimization objectives, so as to reduce the number of variables and improve the optimization efficiency.

[0114] The three variables b with large sensitivity index and comprehensive sensitivity greater than 0.6 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 0.6, and they were determined to be low-sensitivity variables.

[0115] 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.

[0116] 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:

[0117] Step S510: using Box-Behnken design (BBD) to select sample points for constructing a response surface model of various motor performances.

[0118] 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.

[0119] Table 3 BBD level values ​​of optimization variables

[0120]

[0121] 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.

[0122] 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.

[0123] Step S530: performing a significance test on the response surface model of the four optimization objectives.

[0124] 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 0.9998, 0.9997, 0.9968, and 0.9689, respectively, all greater than 0.96, indicating that the response surface models have good fit.

[0125] Step S540: using the non-dominated sorting genetic algorithm II to obtain an optimal solution set based on four optimization objectives.

[0126] 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, as shown in Figure 5 As shown in the figure, 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 4.8 seconds.

[0127] Step S550: Determine the optimal value of the strongly sensitive parameter from the obtained optimal solution set.

[0128] Specifically, several 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. Based on the pursuit of the specific performance of the motor, the optimal value of the highly sensitive parameter is determined. st 18.1mm, b mtl 5.3mm, b m It is 4.4mm.

[0129] Step S600: optimizing the weakly sensitive parameters by using the Taguchi orthogonal method to obtain the optimal values ​​of the weakly sensitive parameters.

[0130] 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:

[0131] 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.

[0132] 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 4.

[0133] Table 4 Orthogonal level values ​​of optimization variables

[0134]

[0135] 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.

[0136] Furthermore, the objective function expression is:

[0137]

[0138] 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.

[0139] 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.

[0140] Specifically, in this example, the value extremes of the four weight factors are set to 0.3, 0.2, 0.3, and 0.2 respectively. The 16 parameter combinations are modeled and solved in turn to obtain the mean and extreme values ​​of the optimization objectives under each variable, and the multi-objective function values ​​of each weakly sensitive variable can be calculated.

[0141] Select the level value of each variable that maximizes the value of the multi-objective optimization function. When the structural parameter combination is A3B2C2D4E3, the performance is optimal, that is, b mtr , b s 、h s 、h mt 、h myThe values ​​are 5.5mm, 5.0mm, 5.0mm, 2.4mm and 6.0mm respectively.

[0142] In order to make the motors on both sides of the energy storage block generate thrust peaks at different times, the stators on the left and right sides are vertically offset by a quarter of the rotor pole pitch. The rotor pole pitch is 14mm, that is, one stator is vertically offset from the other stator by 3.5mm. After the offset, the electric thrust pulsation of the motor is reduced from 133.03% to 39.65%, and the power generation thrust pulsation is reduced from 207.89% to 39.54%. The thrust waveforms generated by the energy storage block before and after the offset are compared. Figure 6 shown.

[0143] Step S700: Perform finite element modeling analysis on the optimal size of the motor to evaluate whether its performance meets the design requirements.

[0144] The initial design and the optimized design were compared and verified by finite element simulation. Table 5 gives the specific dimensions and performance comparison.

[0145] Table 5 Comparison of motor performance before and after optimization

[0146]

[0147] Through optimization, the average thrust and thrust density of the switched reluctance linear motor in the electric state increased by 16.1% and 64.1% respectively, the power density in the generating state increased by 42.2%, and the thrust pulsation decreased by 81.5%. The optimized motor has good performance in both electric and generating states, and can well meet the requirements of the gravity energy storage system.

[0148] On the other hand, the static characteristics of the optimized motor were analyzed. Figure 7 The curve of the change of electromagnetic force when the current increases from 1A to 6A, and the inductance curve of the B-phase winding when the current increases from 2A to 6A are shown. When the mover is in the aligned position, the electromagnetic force is zero and the magnetic resistance is minimum. The trend of static electromagnetic force changing with position under different currents is consistent, and the greater the current, the greater the electromagnetic force. The air gap in the non-aligned position is larger, the magnetic resistance is higher, and the inductance is lower; when aligned, the air gap is small, the magnetic resistance is small, and the inductance is large. The inductance reaches the maximum at the aligned position, and the maximum inductance value gradually decreases as the current increases. When the current is 2A, the maximum inductance of the motor reaches 116.9mH, while the minimum inductance is 41.0mH, and the maximum-minimum inductance ratio reaches 2.85.

[0149] In order to more clearly demonstrate the performance improvement of the novel switched reluctance linear motor described in the present invention, this example makes a detailed comparison between it and the conventional flat gear rotor segmented stator switched reluctance linear motor, the structural schematic diagram of the latter is shown in FIG. Figure 8As shown. Since the double-peak curved rotor tooth surface is an M-shaped structure, the air gap thickness is 0.4mm at the tooth vertex and 0.8mm at the tooth tips on both sides of the pole shoe, and the average air gap thickness is about 0.6mm. For comparison purposes, the air gap thickness of the flat-toothed motor is also set to 0.6mm, that is, the distance between the rotor tooth surface and the stator pole is 0.6mm. The remaining design parameters of the two structures remain the same.

[0150] Fig. 9 The phase inductance characteristics of the two motors are given when the current is 2A and 3A respectively. Although the difference between the minimum inductance values ​​of the two motors is small in the non-aligned position, the maximum inductance value of the double-peak curve tooth structure motor is significantly higher than that of the flat-tooth motor in the aligned position, and it can reach the maximum inductance value faster, thereby achieving a greater inductance change rate. When the current is 2A, the maximum and minimum inductance ratios of the double-peak curve tooth structure motor and the flat-tooth motor are 2.85 and 2.61 respectively; when the current is 3A, the maximum and minimum inductance ratios of the double-peak curve tooth structure motor and the flat-tooth motor are 2.46 and 2.41 respectively. Therefore, compared with the block stator switched reluctance linear motor with a traditional flat-tooth rotor, under the same input conditions, the double-peak curve tooth structure motor can more effectively utilize the input current and generate higher thrust. At the same time, the double-peak curve tooth structure motor is smoother in the maximum inductance area, and the motor can maintain a more stable inductance value when approaching the peak inductance, so that it can better ensure stable thrust output in actual operation. The double-peak curve tooth rotor design enables the motor to better take into account the dual operating conditions of electric power generation and gravity energy storage system.

[0151] The specific performance comparison between the double-peak curve tooth structure motor proposed in the present invention and the traditional flat tooth structure motor is shown in Table 6.

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

[0153]

[0154] Through simulation experiments, it is found that under electric working conditions, the electric average thrust and electric thrust density of the double-peak curve tooth structure motor are increased by 12.7% and 12.4% respectively compared with the flat-tooth motor. Under power generation conditions, compared with the flat-tooth motor, the power generation power density of the double-peak curve tooth structure motor is increased by 41.5%, and the power generation thrust pulsation is reduced by 2.9% when there is no stator misalignment, and it can be reduced by 81.5% after stator misalignment. The simulation results further confirm that compared with the traditional flat tooth structure, the switched reluctance linear motor with a double-peak curve rotor tooth structure proposed in the present invention has a significant improvement in performance.

[0155] It can be seen that the new switched reluctance linear motor proposed in the present invention shows significant advantages in the gravity energy storage system with low speed and high thrust requirements. Not only can it use limited space to generate high thrust to lift heavy objects to a high place under electric conditions, but it can also efficiently convert potential energy into electrical energy and feed it back to the power grid under power generation conditions, thereby improving the energy conversion efficiency of the system and meeting the dual needs of the system under electric and power generation conditions. The stator staggered tooth design further improves the operating stability of the system. The new switched reluctance linear motor of the present invention has a high engineering value in the application of gravity energy storage systems.

[0156] In one embodiment, a novel switched reluctance linear motor optimization design device for a gravity energy storage system is proposed, the device comprising:

[0157] 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;

[0158] The optimization target module selects the optimization target of the switched reluctance linear motor design according to the requirements of the motor in two different working states: electric and generating. In the electric working state, the motor drives the weight to rise, and the electric average thrust F is selected. avg and electric thrust density F ρ As the optimization target; in the power generation working state, the weight is lowered to generate electricity, and the power generation power density P is selected ρ and power generation thrust pulsation F r As an optimization goal;

[0159] The optimization parameter module selects 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 ;

[0160] Sensitivity classification module, which performs sensitivity analysis on optimization parameters and divides design parameters into strong sensitive parameters and weak sensitive parameters;

[0161] The optimal value calculation module of sensitive parameters uses response surface method and genetic algorithm to optimize the strongly sensitive parameters and obtain the optimal value of the strongly sensitive parameters;

[0162] 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;

[0163] The evaluation module is used to perform finite element modeling analysis on the optimal size of the motor and evaluate whether its performance meets the design requirements.

[0164] It should be noted that the optimization design device for the new switched reluctance linear motor for the 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 optimization design method for the new switched reluctance linear motor for the 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 optimization design device for the new switched reluctance linear motor for the gravity energy storage system provided in the above embodiment and the optimization design method embodiment of the new switched reluctance linear motor for the gravity energy storage system belong to the same concept. The implementation process thereof is detailed in the optimization design method embodiment of the new switched reluctance linear motor for the gravity energy storage system, which will not be repeated here.

[0165] 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.

[0166] 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.

[0167] 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 novel switched reluctance linear motor for a gravity energy storage system, characterized in that: The switched reluctance linear motor is a long secondary structure, comprising: The energy storage block moves up and down along the track during the charging and discharging process of the linear motor; The non-magnetic conductive frame is symmetrically arranged on both sides of the energy storage block, 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; Among them, the mover is composed of a mover yoke, a mover pole and a mover pole shoe; the mover pole adopts a double-peak curve tooth structure, and the double-peak curve tooth tip of each mover pole is provided with the mover pole shoe, the midpoint of the double-peak curve tooth and the vertices of the mover pole shoes on both sides are on the same horizontal line, and the lengths and heights of the two arcs of the double-peak curve tooth are consistent.

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

4. The novel switched reluctance linear motor for a gravity energy storage system according to claim 1, characterized in that: The preset distance of the vertical offset of the stators on both sides is: the stators on the left and right are offset by a quarter of the rotor pole pitch in the vertical direction.

5. An optimization design method for a novel switched reluctance linear motor for a gravity energy storage system based on any one of claims 1 to 4, characterized in that: The specific steps of the method are as follows: 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 optimization target of the switched reluctance linear motor design is selected; in the electric working state, the motor drives the weight to rise, and the electric average thrust F is selected avg and electric thrust density F ρ As the optimization target; in the power generation working state, the weight is lowered to generate electricity, and the power generation power density P is selected ρ and power generation thrust pulsation F r As an optimization goal; 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 design 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; Conduct finite element modeling analysis on the optimal size of the motor to evaluate whether its performance meets the design requirements.

6. The design method according to claim 5, 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.

7. The optimization design method according to claim 5, 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 values ​​satisfy ω1+ω2+ω3+ω4=1, and the weight values ​​ω1, ω2, ω3, and ω4 are set to 0.3, 0.2, 0.3, and 0.2 respectively; 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 sensitivity index and comprehensive sensitivity index of the four optimization objectives, the design parameters are divided into strong sensitive parameters and weak sensitive parameters; the three variables b with large sensitivity index and comprehensive sensitivity greater than 0.6 are 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 0.6, and they were determined to be low-sensitivity variables.

8. The optimization design method according to claim 7, 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.

9. The optimization 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, and the multi-objective function value F is calculated. obj ; and 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.

10. An optimization design device for a novel switched reluctance linear motor for a gravity energy storage system according to any one of claims 1 to 4, 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 selects the optimization target of the switched reluctance linear motor design according to the requirements of the motor in two different working states: electric and generating. In the electric working state, the motor drives the weight to rise, and the electric average thrust F is selected. avg and electric thrust density F ρ As the optimization target; in the power generation working state, the weight is lowered to generate electricity, and the power generation power density P is selected ρ and power generation thrust pulsation F r As an optimization goal; The optimization parameter module selects 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, which performs sensitivity analysis on optimization parameters and divides design parameters into strong sensitive parameters and weak sensitive parameters; The optimal value calculation module of sensitive parameters uses response surface method and genetic algorithm to optimize the strongly sensitive parameters and obtain the optimal value of the strongly sensitive parameters; 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 evaluation module is used to perform finite element modeling analysis on the optimal size of the motor and evaluate whether its performance meets the design requirements.

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