CN105844026A - Method for determining working current and time of permanent-magnet linear motor based on taguchi method - Google Patents

Abstract

The invention discloses a method for determining the working current and time of a permanent-magnet linear motor based on a taguchi method. The method comprises the following steps of: firstly, performing temperature rising and cooling tests of a test motor in the event that environmental conditions are constant; then, calculating steady temperature rising and cooling processes of the test motor under different current densities by using an electromagnetic-thermal coupling finite element calculation method, furthermore, comparing simulation and test results, if the simulation and test results are same, drawing out temperature rising and cooling curves of the motor, and if the simulation and test results are not same, modifying a simulation parameter according to an experimental result until the simulation and test results are same; and finally, determining temperature of the motor under different current densities, different operation times and different cooling times according to the determined temperature rising and cooling curves of the motor, and furthermore, obtaining temperature rising combinations most according with engineering practices of the selected motor under the current densities, the operation times and the cooling times by using a taguchi algorithm, such that an optimal combination is obtained.

Description

The method determining permanent-magnetism linear motor operating current and time based on Taguchi's method

Technical field

The present invention relates to linear electric motors design and a kind of permanent magnetism determined under continuous duty of motor utilization ratio part When linear electric motors are applied under periodic duty, the method for the selection of operating current and working time.

Background technology

Along with to motor miniaturization, the improving constantly of requirement of efficient and energy-conservation aspect, permanent-magnetism linear motor is tied with it Structure is simple, and power density is big, and high and accurate positioning the advantage of efficiency carries at Digit Control Machine Tool, emission system and vertical-horizontal The system of liter is widely used.

In order to energy-conservation and improve efficiency, it is sometimes necessary under continuous duty run motor application in short-term or week Under phase duty.According to the feature that the motor feels hot, the motor selecting a continuous duty to run, make the volume of this motor Determine the bearing power that power runs more than short time duty, then motor to run after the heating time constant of 3～4 times Can reach the temperature rise of the highest permission, but the time of short-term operation is the shortest, such motor would not be by heating Make full use of, therefore the motor application worked under continuous duty in short-term or during periodic duty, need according to electricity The heating feature of machine, the feature of heat recovery time etc. rationally selects the power of motor run under continuous duty, determines short Time duty under the electric current density of motor, cyclic duration factor etc..

Taguchi's method is a kind of method of experimental design, and this experimental design is with Probability Theory and Math Statistics as theoretical basis, warp Ji ground, scientifically formulation experimental program to carry out mathematical theory and the method for effective statistical analysis to experimental data. Its basic thought is that Britain statistician R.A.Fisher proposes when carrying out farmland experiment.He finds in an experiment, Environmental condition is difficult to strictly control, and random error is very important, therefore proposes must reasonably arrange experimental program, Make experimental data have suitable mathematical model, to reduce the impact of random error, thus improve experimental result precision and Reliability, the present invention, with electric current density, working time and the cool time of motor as factor of influence, utilizes this thought real When having showed work time under the application of a kind of linear electric motors that can quickly determine under continuous duty and intermittent periodic duty Between and the method for cool time.

Summary of the invention

Technical problem: the invention provides and a kind of determine permanent-magnetism linear motor operating current and time based on Taguchi's method Method, it is possible to determine when the permanent-magnetism linear motor under continuous duty is applied under periodic duty, operating current and work Make the time and cool time selects, thus avoid motor temperature rise too high.

Technical scheme: the method determining permanent-magnetism linear motor operating current and time based on Taguchi's method of the present invention, bag Include following steps:

1) in the case of ambient temperature, wind speed are constant, utilize driver control linear electric motors to move reciprocatingly, use Multi way temperature tester record motor is the temperature in each moment under different electric current densities, according to measured temperature value, until electric When temperature rise in machine half an hour is less than 2 degrees Celsius, this is the temperature rise process of motor, and the temperature now recorded is steady State temperature value；It is then cut off power supply, continues record motor temperature, until motor temperature differs with ambient temperature and is less than 5 degrees Celsius, this is the cooling procedure of motor；

2) by Finite Element Method, motor is carried out electromagnetism and is calculated electromagnetic consumable, then according to described electromagnetic consumable, Simulation parameter, uses the finite element method of Coupled Electromagnetic-Thermal to calculate steady under different electric current densities of experiment electric motor Each moment temperature value in constant temperature liter and cooling procedure, described；

3) relatively described step 1) experimental temperature value and step 2) simulated temperature value, if identical time interval The root-mean-square error of simulation value and experiment value less than 5%, then draw out this motor with simulation result close at different electric currents Temperature rise under Du and cooling chart, otherwise according to returning step 2 after experimental result correction simulation parameter)；

4) according to requirement and the temperature characteristic of motor of motor duty, select in described temperature rise with cooling chart Motor operation time under different electric current densities and parameter cool time；

5) according to described step 4) in operation time under the different electric current densities that select, cool time, use field mouth Algorithm draws and meets motor duty and the electric current density of motor temperature characteristic, operation time, optimum combination cool time.

Further, in the inventive method, the simulation parameter in described step (2) is motor slot portion mixing material The heat conductivity of other part homogenous materials of Equivalent Thermal Conductivities, motor, the thermal parameter of motor each several part, motor and ring Convection coefficient between border.

Further, in the inventive method, the Equivalent Thermal Conductivities of described motor slot portion mixing material is based on Gasar The method of porous material calculation of thermal conductivity, does Equivalent to the windings section of linear electric motors, then according to heat The method of resistance, the motor windings section Equivalent Thermal Conductivities that Equivalent Calculation goes out.

Further, in the inventive method, described step 3) in simulation value and experiment value root-mean-square error according under Formula calculates:

$\mathrm{\σ}=\sqrt{\frac{\underset{\mathrm{\ι}=1}{\overset{\mathrm{\ν}}{\mathrm{\Σ}}}({\mathrm{\Ξ}}_{\mathrm{\ρ}}-{\mathrm{\Ξ}}_{\mathrm{\φ}})}{\mathrm{\ν}}}$

Wherein σ is root-mean-square error, X_rFor experiment value, X_fFor simulation value, n is that motor temperature rise reaches steady state time After, it is spaced the temperature data group number that the identical time reads respectively, often group data are by corresponding simulation value and experiment value structure Become.

Further, in the inventive method, described step 3) in correction simulation parameter be according to below equation respectively Calculate revised convection coefficient and Equivalent Thermal Conductivities:

The computing formula of convection coefficient is:

H=N_uλ/δ

Wherein, h is convection coefficient, and λ is heat conductivity, and δ is characteristic length, N_uIt is nusselt number, N_u=C (Gr_LP_r)², C is empirical coefficient, Gr_LIt is grashof number, P_rIt it is Prandtl constant；

The Equivalent Thermal Conductivities of motor slot portion mixing material is:

${\mathrm{\λ}}_{\mathrm{eq}}=L/\frac{1}{2}\mathrm{\β}\·(\frac{d_2}{{\mathrm{\λ}}_{\mathrm{cop}}}+\frac{(d_1-d)\·d_2}{d_1{\mathrm{\λ}}_{\mathrm{ena}}}+\frac{d_2-d_1}{{\mathrm{\λ}}_{\exp }})$

Wherein, β is correction factor, λ_eq、λ_cop、λ_ena、λ_expBe respectively windings section Equivalent Thermal Conductivities, The heat conductivity of copper, the heat conductivity of enamel-covered wire, the heat conductivity of epoxy resin, L is the radical length of groove, d, d₁、 d₂It is respectively that the thickness of copper part of equivalent unit, copper add the thickness of enamel-covered wire, copper adds enamel-covered wire to add epoxy resin total Thickness.

The inventive method can determine when the permanent-magnetism linear motor under continuous duty is applied under periodic duty, work Electric current and working time and the selection of heat recovery time.The method is by the calculating of Coupled Electromagnetic-Thermal and experimental verification Method, matching draws the motor temperature rise curve under different electric current density and heat recovery time curve, then according to this two The selection of individual curve makes motor reach to allow the time n (n >=2) of maximum temperaturerise individual and make temperature reduce to some value The required time, and provide the temperature under every kind of ageing and electric current density combination, finally set with Taguchi's method The factor that sets the goal draws optimum combination.

The present invention based on emulation and experimentation linear electric motors continuous duty under operation time different electric current densities under temperature The parameters such as the cool time of liter and correspondence work in the impact of the temperature rise under periodic duty to this motor, it is then determined that one Group optimum combination.In a word, the present invention can determine the permanent-magnet linear electricity of work continuously easily and fast according to experimental data Machine application and electric current density during periodic duty, work and cool time.

Beneficial effect: the present invention compared with prior art, has the advantage that

(1) for the calculating of motor slot portion Equivalent Thermal Conductivities, already present research method is based on winding layers equivalence mould Type, needs according to motor slot portion geometric model, layers of material Equivalent Calculation, and final employing thermo network solves, and solves Process is complicated and precision is poor.And present invention method based on Gasar porous material calculation of thermal conductivity is set up model and is asked Solving, this Method Modeling is junior unit modeling the most complicated model partition, goes out whole by model of element analysis and solution The calculating of the Equivalent Thermal Conductivities of individual model.Model simplification and calculate simple, can effectively calculate motor slot portion Heat conductivity.These computational methods are verified by experiment.

(2) for the selection of the motor under intermittent duty, most method needed according to the cyclic duration factor time Calculating the loss of electric machine (i.e. heating), calculating is complicated and error is bigger.And based on field mouth statistical method, it is only necessary to On the basis of experiment, emulation the data obtained is optimized combination, it is possible to obtain different electric current density, operation Time and the maximum temperaturerise of the lower motor of combination cool time, it is to avoid must carry out testing and each combine under emulation divide Analysis, time-consuming and resource.

Accompanying drawing explanation

Fig. 1 groove portion equivalent physical model, Fig. 1 a is groove portion model, and Fig. 1 b is the model of element in groove portion；

Fig. 2 groove portion equivalent thermal resistance model；

Temperature rise curve under Fig. 3 linear electric motors difference electric current density；

Cooling curve under Fig. 4 linear electric motors difference electric current density；

Fig. 5 Taguchi's method solving result figure.

Fig. 6 is the inventive method flow chart.

Detailed description of the invention

Below in conjunction with embodiment and Figure of description, the present invention is further illustrated.

(1) in the case of environmental condition is constant, experiment electric motor is carried out temperature rise and cooling test；

Experimental apparatus includes that linear electric motors, oscillograph, driver, computer, multi way temperature tester, temperature pass Sensor etc..Experimentation is: in the case of ensureing that environmental condition is constant, back and forth transport with driver drives linear electric motors Dynamic and constant by the electric current density of motor during oscillograph test run；By being embedded in the temperature of motor various location Degree sensor, is separately recorded under different electric current density with multi way temperature tester, and motor is from starting to stable temperature rise Each temperature value setting the moment.

Experiment purpose be in order to verify emulation solve time each parameter calculate reasonability, facilitate application simulation data assessment The performance of motor, needs to adjust Emulation of Electrical Machinery parameter by the result of experiment the most in this process.The electricity drawn The temperature rise of machine and cooling curve are as shown in Figure 3 and Figure 4.Figure selects with 5A/mm²The steady temperature 63 DEG C work of work For maximum operating temperature, 6A/mm can be read²、7A/mm²、8A/mm²Needed for electric current density is issued to 63 DEG C The time wanted, then can read the temperature of the motor after different cool time according to Fig. 2.

(2) finite element method using Coupled Electromagnetic-Thermal calculates experiment electric motor stablizing under different electric current densities Temperature rise and cooling procedure；

The FEM (finite element) model of application motor carries out Coupled Electromagnetic-Thermal emulation, and each thermal parameter in model includes composition electricity The heat conductivity of the various homogenous material of machine, the calculating of the heat conductivity of the composites such as groove portion, and various free convection And the computational methods of laminar convection boundary condition.This kind of material can be found by consulting reference materials for various single materials Material Thermal Parameter at different temperatures, but for being mixed groove portion filling part by many kinds of substance, need root Calculate according to the relevant knowledge of thermal conduction study, Electrical Motor.Here the Equivalent Thermal Conductivities of linear electric motors windings section is given Computational methods:

Method based on Gasar porous material calculation of thermal conductivity, does equivalent model the windings section of linear electric motors and divides Analysis, then according to the method for thermal resistance, Equivalent Calculation goes out the Equivalent Thermal Conductivities of motor windings section, windings section etc. Effect model and equivalent thermal resistance are as depicted in figs. 1 and 2.The computing formula of Equivalent Thermal Conductivities is:

${\mathrm{\λ}}_{\mathrm{ep}}=L/\frac{1}{2}\mathrm{\β}\·(\frac{d_2}{{\mathrm{\λ}}_{\mathrm{cop}}}+\frac{(d_1-d)\·d_2}{d_1{\mathrm{\λ}}_{\mathrm{ena}}}+\frac{d_2-d_1}{{\mathrm{\λ}}_{\exp }})$

Wherein, β is correction factor, λ_eq、λ_cop、λ_ena、λ_expIt is respectively the Equivalent Thermal Conductivities of windings section, the leading of copper Hot coefficient, the heat conductivity of enamel-covered wire, the heat conductivity of epoxy resin.L is the radical length of groove, d, d₁、d₂As Shown in Fig. 1 (b), the respectively thickness of the copper part of equivalent unit, copper adds the thickness of enamel-covered wire, and copper adds enamel-covered wire and adds The thickness that epoxy resin is total.The result of calculation of part heat conductivity is as shown in table 1.

The calculating of convection boundary condition can be calculated according to the correlation model of thermal conduction study and computing formula.

(3) compare the result of emulation and experiment, if consistent, draw out temperature rise and the cooling curve of this motor, if Simulation result differs with experimental result, then according to the windings section affecting heat dissipation capacity in interpretation phantom Heat conductivity, convection coefficient between motor gas-gap and between motor and environment.Simulation comparison the most again, until imitative True result is less than 5% with the root-mean-square value of experimental result.

The computing formula of convection coefficient is:

H=N_uλ/δ

Wherein, h is convection coefficient, and λ is heat conductivity, and δ is characteristic length, N_uIt is nusselt number, N_u=C(Gr_LP_r)², C is empirical coefficient, Gr_LIt is grashof number, P_rIt it is Prandtl constant；

The Equivalent Thermal Conductivities of windings section is:

$\frac{L}{{\mathrm{\λ}}_{\mathrm{eq}}}=\frac{1}{2}\mathrm{\β}\·(\frac{d_2}{{\mathrm{\λ}}_{\mathrm{cop}}}+\frac{(d_1-d)\·d_2}{d_1{\mathrm{\λ}}_{\mathrm{ena}}}+\frac{d_2-d_1}{{\mathrm{\λ}}_{\exp }})$

Wherein, β is correction factor, λ_eq、λ_cop、λ_ena、λ_expIt is respectively the Equivalent Thermal Conductivities of windings section, the leading of copper Hot coefficient, the heat conductivity of enamel-covered wire, the heat conductivity of epoxy resin.L is the radical length of groove, d, d₁、d₂ As shown in Fig. 1 (b), the respectively thickness of the copper part of equivalent unit, copper adds the thickness of enamel-covered wire, and copper adds enamel-cover Line adds the thickness that epoxy resin is total.

(4) temperature rise and cooling curve according to the motor determined determine that this motor is in different electric current densities, different operation Temperature under time, different cool time

Data shown in table 2 can be listed according to Fig. 3 and Fig. 4, determine each electric current density, operation time, cool time Under the temperature of motor.

(5) application Taguchi's method draws the lowest temperature rise under selected current of electric density, operation time, cool time Combination, i.e. draws optimum combination.

Application Minitab software field mouth computational methods, selections temperature is object function, electric current density, operation the time, Cool time is the factor, and gained form is carried out data statistic analysis, acquired results as it is shown in figure 5, in figure electric current close Spend (pacifying every square millimeter), run the time (second) and refer respectively to the horizontal seat of corresponding figure cool time (second) Mark, electric current density is 5A/mm as seen from the figure²Lower operation one working time 1200s, cool time 1500s The temperature of cycle rear motor is minimum, and electric current density is 8A/mm²Lower operation 3100s, the temperature of cooling 800s is the highest.

The heat conductivity of table 1 portion of material

Material	Heat conductivity when 20 degrees Celsius (watt/ meter Du)
		Stalloy	66.1
Groove portion equivalent material	0.172
		Permanent magnet	8.949
Air	0.0217

Table 2 motor temperature under different electric current densities, different operation time and cool time parameter

Above-described embodiment is only the preferred embodiment of the present invention, in actual application, according to motor long time work The temperature rise of system and electric current density feature, technical staff only needs to measure certain operation time under different electric current density and cold But the temperature rise under the time, then uses the Taguchi's method of minitab software both can draw one group of compound mode of optimum. Therefore this kind of method can determine the operating scheme of motor efficiently, improves motor operational efficiency.In addition, at electricity During machine structure optimization, if a certain target is affected by several factors, it is also possible to solve with Taguchi's method and obtain one The result optimized.

Claims (5)

1. the method determining permanent-magnetism linear motor operating current and time based on Taguchi's method, it is characterised in that The method comprises the following steps:

1) in the case of ambient temperature, wind speed are constant, utilize driver control linear electric motors to move reciprocatingly, use Multi way temperature tester record motor is the temperature in each moment under different electric current densities, according to measured temperature value, until electric When temperature rise in machine half an hour is less than 2 degrees Celsius, this is the temperature rise process of motor, and the temperature now recorded is steady State temperature value；It is then cut off power supply, continues record motor temperature, until motor temperature differs with ambient temperature and is less than 5 degrees Celsius, this is the cooling procedure of motor；

2) by Finite Element Method, motor is carried out electromagnetism and is calculated electromagnetic consumable, then according to described electromagnetic consumable, Simulation parameter, uses the finite element method of Coupled Electromagnetic-Thermal to calculate steady under different electric current densities of experiment electric motor Each moment temperature value in constant temperature liter and cooling procedure；

3) relatively described step 1) experimental temperature value and step 2) simulated temperature value, if identical time interval The root-mean-square error of simulation value and experiment value less than 5%, then draw out this motor with simulation result close at different electric currents Temperature rise under Du and cooling chart, otherwise according to returning step 2 after experimental result correction simulation parameter)；

4) according to requirement and the temperature characteristic of motor of motor duty, select in described temperature rise with cooling chart Motor operation time under different electric current densities and parameter cool time；

5) according to described step 4) in operation time under the different electric current densities that select, cool time, use field mouth Algorithm draws and meets motor duty and the electric current density of motor temperature characteristic, operation time, optimum combination cool time.

The method determining permanent-magnetism linear motor operating current and time based on Taguchi's method the most according to claim 1, It is characterized in that: described step 2) in simulation parameter be the Equivalent Thermal Conductivities of motor slot portion mixing material, motor Convection coefficient between the heat conductivity of other part homogenous materials, motor and environment.

The method determining permanent-magnetism linear motor operating current and time based on Taguchi's method the most according to claim 2, It is characterized in that: the Equivalent Thermal Conductivities of described motor slot portion mixing material is to calculate based on Gasar porous material to lead The method of hot coefficient, does Equivalent to the windings section of linear electric motors, then according to the method for thermal resistance, and equivalence The motor windings section Equivalent Thermal Conductivities calculated.

4. according to claim 1,2 or 3, determine permanent-magnetism linear motor operating current and time based on Taguchi's method Method, it is characterised in that: described step 3) in the root-mean-square error of simulation value and experiment value calculate according to following formula:

$\mathrm{\σ}=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(X_r-X_f)}{n}}$

Wherein σ is root-mean-square error, X_rFor experiment value, X_fFor simulation value, n is that motor temperature rise reaches steady state time After, it is spaced the temperature data group number that the identical time reads respectively, often group data are by corresponding simulation value and experiment value structure Become.

5. according to claim 1,2 or 3, determine permanent-magnetism linear motor operating current and time based on Taguchi's method Method, it is characterised in that: described step 3) in correction simulation parameter be to calculate correction respectively according to below equation After convection coefficient and Equivalent Thermal Conductivities:

The computing formula of convection coefficient is:

H=N_uλ/δ

Wherein, h is convection coefficient, and λ is heat conductivity, and δ is characteristic length, N_uIt is nusselt number, N_u=C (Gr_LP_r)², C is empirical coefficient, Gr_LIt is grashof number, P_rIt it is Prandtl constant；

The Equivalent Thermal Conductivities of motor slot portion mixing material is:

${\mathrm{\λ}}_{\mathrm{eq}}=L/\frac{1}{2}\mathrm{\β}\·(\frac{d_2}{{\mathrm{\λ}}_{\mathrm{cop}}}+\frac{(d_1-d)\·d_2}{d_1{\mathrm{\λ}}_{\mathrm{ena}}}+\frac{d_2-d_1}{{\mathrm{\λ}}_{\exp }})$

Wherein, β is correction factor, λ_eq、λ_cop、λ_ena、λ_expBe respectively windings section Equivalent Thermal Conductivities, The heat conductivity of copper, the heat conductivity of enamel-covered wire, the heat conductivity of epoxy resin, L is the radical length of groove, d, d₁、 d₂It is respectively that the thickness of copper part of equivalent unit, copper add the thickness of enamel-covered wire, copper adds enamel-covered wire to add epoxy resin total Thickness.