CN105356679A - Design method of flux-switching outer rotor motor based on electric heating two-way coupling - Google Patents

Abstract

The present invention discloses a design method of a flux-switching outer rotor motor based on electric heating two-way coupling. A two-dimensional finite element model and a -dimensional temperature field model are used, the multiple-physical-field joint simulation model of an electromagnetic field and a temperature field is established, the influence of temperature on motor driving performance caused by the influence of temperature on a motor material is considered, especially the influence of temperature on a permanent magnet steel material is considered, an electric heating two-way coupling analysis method is introduced, and the influence brought by a temperature factor ignored in a traditional design method is analyzed and obtained through iterative feedback analysis. The structural parameter of the motor is associated in the design process, a correction factor is analyzed and obtained by using two-way coupling so as to compensate the influence of the temperature on the motor driving performance, the stator inner diameter and stator pole arc coefficient of the motor are optimized through the obtained correction factor, thus a motor size is modified, and the requirement can be satisfied when the motor runs in a complex condition.

Description

Magnetic flux based on electric heating bidirectional coupled switches the method for designing of external rotor electric machine

Technical field

The invention belongs to flux switch motor technical field, specifically based on the Optimization Design of the magnetic flux switching external rotor electric machine of electric heating bidirectional coupled.

Background technology

Drive motors is one of crucial power part of electric motor car, the quality of its performance directly affects the driveability of car load, require the performances such as its concrete high power density, high torque density, high efficiency and wide speed regulating range, to meet the service requirement of the different operating modes such as the frequent acceleration and deceleration of electric automobile, climbing, high-performance cruise.

Flux switch permanent magnet motor is used in electric automobile field, the permanent magnetic steel tangentially alternately magnetized is embedded with between flux switch permanent magnet motor adjacent stators, on the one hand, higher torque and power density is achieved by poly-magnetic effect, on the other hand, compared with conventional permanent magnet brushless motor, on its rotor both without permanent magnetic steel also without winding, make electric machine structure simple, be conducive to again heat radiation while being applicable to high-speed cruising, the requirement of the different operating condition such as the frequent acceleration and deceleration of electric automobile, heavy duty climbing, at a high speed continuation of the journey can be met.A kind of six phase Magneticflux-switching type magnetoes are proposed in the document of China Patent No. 201310173635.7, rotor structure is similar to switched reluctance machines, without winding without permanent magnetic steel, only formed by silicon steel plate stacking, remain common three-phase magnetic pass switching electromotor high power density and high efficiency inherent characteristics, owing to adopting the particular design of six phase windings, compare three phase electric machine to decrease to the requirement of power inverter under Same Efficieney class requirement, make to affect larger space harmonics number of times to increase, and amplitude declines, and then reduce the amplitude of torque pulsation.A kind of flux switch permanent magnet motor being applicable to stroke-increasing electric automobile is proposed in the document of China Patent No. 201410781916.5, inner and outer rotors is salient-pole structure, stator core adopts H-shaped modularized design, embed the permanent magnetic steel of alternately cutting orientation magnetizing in stator, armature winding is as in stator slot; This motor is compared traditional individual layer air-gap flux switching and is had higher torque and power density; Owing to there is inside and outside two-layer air gap, make this motor effectively the permanent magnetic energy of the supersaturation part of traditional flux switch motor stator tooth can be converted to external magnetic field, thus the degree of saturation of stator tooth can be reduced, effectively can also improve the torque output capability of motor and improve the power density of motor.But above-mentioned two kinds of motors are all based upon on the basis of traditional design method.So-called traditional design method refers in the design process, and the motor performances such as the power output of motor, average Driving Torque carry out designing drawing only considering in ambient room temperature situation.But, along with the development rapidly of electric automobile, the running environment of electric automobile is more and more severe, the operating modes such as such as frequent anxious acceleration, heavy duty climbing, larger armature supply can make winding temperature raise fast at short notice, simultaneously, in motor, the service behaviour of permanent magnetic steel is very responsive to temperature, temperature rising can make permanent magnetic steel Point Drifting, even can cause the irreversible demagnetization of permanent magnetic steel, finally causes motor driveability to decline.

Therefore, how to obtain and a kind ofly consider that the design of electrical motor method of temperature on the impact of motor driveability becomes problem demanding prompt solution in current power automotive field.

Summary of the invention

The object of the invention is not consider when designing the problem that temperature affects driveability for solving existing motor, a magnetic flux based on electric heating bidirectional coupled is provided to switch the method for designing of external rotor electric machine, introduce the impact that electric heating bidirectional coupled analytical method is brought motor driven nature the subject of knowledge and the object of knowledge with compensation temperature, meet the driveability requirement of electric automobile.

For achieving the above object, the technical solution used in the present invention is: the power output P of selected motor ₂, rated power P, rated speed n, electric efficiency η, motor axial length l _a, stator poles p _s, rotor number of poles p _r, motor flux leakage coefficient k _d, skew slot factor k _s, motor lines load A _sand air gap flux density maximum B _gmaxthese parameters; Calculate the initial stator pole embrace c of motor _s, initial rotor pole embrace c _r, initial permanent magnet polar arc c _pm, initial stator rabbet polar arc c _slotwith initial diameter of stator bore D _si; Two-dimensional electromagnetic field model under utilizing Maxwell software to set up the ambient temperature of motor, utilizes Maxwell software emulation to go out the average Driving Torque T of motor _em, core loss P _fewith permanent magnetic steel eddy current loss P _e, and calculate copper loss P _cu, it is characterized in that further comprising the steps of:

A, set up three dimensional temperature field model in conjunction with Fluent software, by core loss P _fe, permanent magnetic steel eddy current loss P _ewith copper loss P _cuimport to three dimensional temperature field model, emulation obtains temperature T when motor operation reaches stable _n;

B, to calculate motor in temperature be T _ntime the residual magnetic flux density B that inscribes _r(T _n) and be HCJ H _ci(T _n), upgrade the permanent magnetic steel demagnetization curve under ambient temperature, obtain motor at temperature T _nunder permanent magnetic steel demagnetization curve, will upgrade after temperature T _nunder permanent magnetic steel demagnetization curve data feedback to described two-dimensional electromagnetic field model, obtain temperature T _nunder two-dimensional electromagnetic field model;

C, Maxwell software emulation is utilized to go out motor at temperature T _nunder average Driving Torque T _{em (Tn)}, core loss P _{fe (Tn)}, permanent magnetic steel eddy current loss P _{e (Tn)}and calculate copper loss P _{cu (Tn)}, by core loss P _{fe (Tn)}, permanent magnetic steel eddy current loss P _{e (Tn)}with copper loss P _{cu (Tn)}import in three dimensional temperature field model, obtain temperature T when motor operation reaches stable _n+1;

D, C.T T _nand T _n+1, when not satisfying condition | T _n-T _n+1| during≤σ, σ is temperature design precision, then upgrade temperature T _nunder permanent magnetic steel demagnetization curve, obtain motor at temperature T _n+1the permanent magnetic steel demagnetization curve of lower correspondence, then obtain temperature T _n+1the average Driving Torque T of lower correspondence _{em (Tn+1)}, core loss P _{fe (Tn+1)}, permanent magnetic steel eddy current loss P _{e (Tn+1)}with copper loss P _{cu (Tn+1)}, and again to import in three dimensional temperature field model, obtain motor and run temperature T when reaching stable _n+2, then by temperature T _n+2compare, so circulation is until satisfy condition; When satisfying condition | T _n-T _n+1| during≤σ, then first simulate motor at temperature T _n+1under average Driving Torque T _{em (Tn+1)}, then judge average Driving Torque T _{em (Tn+1)}whether equal average Driving Torque T _emif be not equal to, then first calculate torque scale factor and modifying factor then through formula D _{si (temp)}=m ₁d _siand c _{s (temp)}=m ₂c _srevise described initial diameter of stator bore D _siwith described initial stator pole embrace c _s, the diameter of stator bore D after being optimized _{si (temp)}with stator pole embrace c _{s (temp)}, m ₁and m ₂be respectively the diameter of stator bore D after optimization _{si (temp)}with stator pole embrace c _{s (temp)}correction factor, k=m ² ₁m ₂.

Diameter of stator bore D after being optimized _{si (temp)}with stator pole embrace c _{s (temp)}after, calculate the average Driving Torque T after optimization _{em (temp)}:

$T_{em\left(temp\right)}=\frac{\sqrt{2}{\mathrm{\π}}^2}{4}{\mathrm{MD}}_{si\left(temp\right)}^2{c}_{s\left(temp\right)},M=\frac{P_r}{P_s}{k}_s{k}_d{A}_s{l}_a{B}_{g\max }^{\′}\mathrm{\η}.$

Average Driving Torque T after being optimized _{em (temp)}afterwards, to initial rotor pole embrace c _rwith initial permanent magnetic steel polar arc c _pmbe optimized for: $\left\{\begin{array}{c}0.25\≤c_{rn}\≤0.39\\ 0.14\≤c_{pmn}\≤0.24\end{array}\right.,$ C _rnfinal rotor pole arc coefficient, c _pmnit is final permanent magnetic steel polar arc.

The beneficial effect that the present invention has after adopting technique scheme is:

1, the present invention considers that the impact of temperature on motor material causes temperature on the impact of motor driveability, especially on the impact of permanent magnetic steel material, introduce electric heating bidirectional coupled analytical method, obtain by the feedback analysis that iterates the impact that temperature factor that traditional design method ignores brings.Bidirectional coupled analysis is utilized to obtain modifying factor, its effect is the impact that compensation temperature is brought motor driven nature the subject of knowledge and the object of knowledge, ignore impact that temperature rise brings motor driven nature the subject of knowledge and the object of knowledge to such an extent as to the problem that requires of the driveability that can not meet electric automobile to solve in traditional design method, make motor operate in complex working condition and also can meet the demands.

2, the present invention is associated with the structural parameters of motor in the design process, diameter of stator bore and the stator pole embrace of motor is optimized by the modifying factor of the motor obtained, thus amendment motor size, by requirement and the material cost of the motor driveability in conjunction with design, obtain the design of electrical motor considering temperature factor optimum.

3, the present invention utilizes two-dimensional finite element model and three dimensional temperature field model, set up the multiple physical field associative simulation model in electromagnetic field-temperature field, utilize finite element can shorten design time, reduce design cost, improve counting accuracy, there is simplicity of design, simple to operate, operating efficiency advantages of higher.

4, the present invention utilizes the multiple physical field joint simulation method of bidirectional coupled, can calculate the driveability of motor under different operating mode in real time.

Accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments, the invention will be further described.

Fig. 1 is the radial section structural representation that magnetic flux switches external rotor electric machine;

Fig. 2 is the design flow diagram of the magnetic flux switching external rotor electric machine based on electric heating bidirectional coupled;

Fig. 3 is the intrinsic demagnetization curve of permanent magnetic steel at 20 DEG C of temperature;

Fig. 4 is that the average Driving Torque that designs of the present invention and traditional design method is to comparison diagram;

Fig. 5 is the average Driving Torque figure of the motor with the inventive method design.

In figure: 1. rotor; 2. stator; 3. armature winding; 4. non-magnetic rotating shaft; 5. permanent magnetic steel.

Embodiment

As shown in Figure 1, the structure of three-phase 12/22 pole magnetic flux switching external rotor electric machine is: be made up of rotor 1, stator 2, armature winding 3 and non-magnetic rotating shaft 4, rotor 1 is fixedly sleeved in non-magnetic rotating shaft 4, rotates with non-magnetic rotating shaft 4.Rotor 1 and stator 2 are salient-pole structure, rotor 1 both without winding also without permanent magnetic steel 5, be only formed by stacking by silicon steel sheet.The stator rabbet of stator 2 becomes " V " type, and 12 pieces of rectangle permanent magnetic steels 5 tangentially alternately magnetized are embedded on stator 2, and armature winding 3 is around with on stator 2.

External rotor electric machine is switched for the magnetic flux shown in Fig. 1, the present invention is in conjunction with the permanent magnet flux demagnetization curve under different temperatures, namely represent the curve that the magnetic flux density of permanent magnetic steel 5 changes with magnetic field intensity, based on electric heating bidirectional coupled analytical method, the impact that temperature factor that traditional design method ignores brings is obtained by iterative feedback analysis repeatedly, determine the modifying factor of motor, carry out the optimal design of diameter of stator bore and stator pole embrace on this basis.Electric heating bidirectional coupled method is wherein a kind of method that multiple physical field associative simulation model based on electromagnetic field and temperature field obtains value of feedback.As shown in Figure 2, specifically comprise the following steps:

Step 1: the actual design demand switching external rotor electric machine according to magnetic flux, the parameters such as rated power P, the rated speed n of selected magnetic flux switching external rotor electric machine and electric efficiency η.

The power output P of motor is selected by traditional design method ₂, rated power P, rated speed n, electric efficiency η, motor axial length l _a, stator poles p _s, rotor number of poles p _r, motor flux leakage coefficient k _d, skew slot factor k _s(k in the present invention _s=1), motor lines load A _sand air gap flux density maximum B _gmaxthese parameters.These parameters are no longer optimized in ensuing process of optimization.

According to selected parameter, calculate the original dimension of motor, namely calculate the initial stator pole embrace c of motor _s, initial rotor pole embrace c _r, initial permanent magnet polar arc c _pm, initial stator rabbet polar arc c _slotwith initial diameter of stator bore D _si, computing formula is as follows:

$c_s=c_r=c_{pm}=\frac{\mathrm{\π}}{90p_s}---\left(1\right)$

$c_{slot}=\frac{\mathrm{\π}}{30p_s}---\left(2\right)$

$D_{si}=\sqrt{\frac{P_2}{\frac{\sqrt{2}{\mathrm{\π}}^3}{120}\frac{P_r}{P_s}{k}_s{k}_d{A}_s{l}_a{B}_{g\max }{c}_{s}n\mathrm{\η}}}---\left(3\right)$

Step 2: according to rated power P, rated speed n, electric efficiency η, the power output P of motor ₂, motor axial length l _a, stator poles p, rotor number of poles p _r, motor flux leakage coefficient k _d, skew slot factor k _s, motor lines load A _sand air gap flux density maximum B _gmaxwith the initial diameter of stator bore D that step 1 calculates _si, initial stator pole embrace c _s, initial rotor pole embrace c _rwith initial permanent magnetic steel polar arc c _pm, utilize Maxwell software to set up this magnetic flux and switch the two-dimensional electromagnetic field model of external rotor electric machine under ambient temperature (20 DEG C).

Step 3: for two-dimensional electromagnetic field model, carries out electromagnetic performance emulation and Analysis of Electromagnetic Properties based on Maxwell software to motor.Analyze based on the permanent magnetic steel demagnetization curve under ambient temperature (20 DEG C), as shown in Figure 3, abscissa represents magnetic field intensity H, and ordinate represents magnetic induction density B.As H=0, the numerical value of permanent magnetic steel demagnetization curve and ordinate intersection is residual magnetic flux density B _rvalue; As B=0, the permanent magnetic steel demagnetization curve numerical value crossing with abscissa is HCJ H _civalue.

Maxwell software is utilized to go out the average Driving Torque T of motor to Emulation of Electrical Machinery _em, core loss P _fewith permanent magnetic steel eddy current loss P _e.Recycling formulae discovery goes out copper loss P _cu, computing formula is as follows:

P _cu＝mI ²R(4)

In formula, m is number of motor phases, and R is the effective resistance value of every phase winding, and I is the effective value of phase current in winding.

Step 4: adopt motor axial length l _a, stator poles p _s, rotor number of poles p _r, motor flux leakage coefficient k _d, skew slot factor k _s, motor lines load A _sand air gap flux density maximum B _gmaxwith initial diameter of stator bore D _si, initial stator pole embrace c _s, initial rotor pole embrace c _rwith initial permanent magnetic steel polar arc c _pm, then set up in conjunction with Fluent software the three dimensional temperature field model that magnetic flux switches external rotor electric machine.Thereafter core loss P step 3 calculated _fe, permanent magnetic steel eddy current loss P _ewith copper loss P _cuimporting to the magnetic flux set up switches in the three dimensional temperature field model of external rotor electric machine, obtains magnetic flux switch external rotor electric machine and run temperature T when reaching stable at ambient temperature by Fluent emulation _n.

Step 5: be T in temperature _nin time, inscribes, and is gone out the residual magnetic flux density B of the permanent magnetic steel demagnetization curve of motor by following formulae discovery _r(T _n) and be HCJ H _ci(T _n):

$\left\{\begin{array}{c}{B}_r\left(T_n\right)=B_r\left(T_{ref}\right)\·\[1+{\mathrm{\α}}_1(T_n-T_{ref})+{\mathrm{\α}}_2{(T_n-T_{ref})}^2\]\\ =B_r\left(T_{ref}\right)\·P\left(T_n\right)\\ H_{ci}\left(T_n\right)=H_{ci}\left(T_{ref}\right)\·\[1+{\mathrm{\β}}_1(T_n-T_{ref})+{\mathrm{\β}}_2{(T_n-T_{ref})}^2\]\\ =H_{ci}\left(T_{ref}\right)\·Q\left(T_n\right)\end{array}\right.---\left(5\right)$

Wherein, T _refreference temperature, B _r(T _ref) and H _ci(T _ref) to be respectively temperature be T _reftime the residual magnetic flux density of inscribing and HCJ, α ₁, α ₂, β ₁and β ₂it is the temperature coefficient of permanent magnetic steel material.

Based on the residual magnetic flux density B that formula (5) calculates _r(T _n) and HCJ H _ci(T _n), obtained at temperature T by following formulae discovery _nunder permanent magnetic steel demagnetization curve, namely upgrade the permanent magnetic steel demagnetization curve under ambient temperature (20 DEG C), obtain motor at temperature T _nunder permanent magnetic steel demagnetization curve:

$\left\{\begin{array}{c}{B}_i\left(T_n\right)=b_i\left(T_{ref}\right)\·B_r\left(T_n\right)\\ H_i\left(T_n\right)=h_i\left(T_{ref}\right)\·H_{ci}\left(T_n\right)\end{array}\right.---\left(6\right)$

Wherein: $\left\{\begin{array}{c}{b}_i\left(T_{ref}\right)=B_i\left(T_{ref}\right)/B_r\left(T_{ref}\right)\\ h_i\left(T_{ref}\right)=H_i\left(T_{ref}\right)/H_{ci}\left(T_{ref}\right)\end{array}\right.---\left(7\right)$

Wherein, B _i(T _ref), H _i(T _ref) and B _i(T _n), H _i(T _n) be respectively temperature T _refwith temperature T _nunder magnetic flux density and magnetic field intensity.By the renewal rear motor that obtains at temperature T _nunder the magnetic flux set up to step 2 of permanent magnetic steel demagnetization curve data feedback switch two-dimensional electromagnetic field model under the ambient temperature of external rotor electric machine, obtain temperature T _nthe two-dimensional electromagnetic field model of lower motor.

With reference to step 3, adopt the identical method with step 3, based on Maxwell software, electromagnetic performance emulation and Analysis of Electromagnetic Properties are carried out to motor, utilize Maxwell software to go out motor at temperature T to Emulation of Electrical Machinery _nunder average Driving Torque T _{em (Tn)}, core loss P _{fe (Tn)}, and the eddy current loss P of permanent magnetic steel 5 _{e (Tn)}with copper loss P _{cu (Tn)}, and by core loss P _{fe (Tn)}, permanent magnetic steel eddy current loss P _{e (Tn)}with copper loss P _{cu (Tn)}import in three dimensional temperature field model, obtain temperature T when motor operation reaches stable by Fluent emulation _n+1.

Step 6: the temperature T that comparison step 4 calculates _nwith the temperature T that step 5 calculates _n+1, it is as follows that it compares formula:

|T _n-T _n+1|≤σ(8)

Wherein, σ is according to the given temperature design precision of the requirement of temperature convergence, when not satisfying condition | T _n-T _n+1| during≤σ, then upgrade the temperature characterisitic of material under corresponding temperature, namely adopt the method identical with step 5 to upgrade temperature T _n+1corresponding permanent magnetic steel demagnetization curve, namely upgrades temperature T _nunder permanent magnetic steel demagnetization curve, obtain motor at temperature T _n+1the permanent magnetic steel demagnetization curve of lower correspondence.And then adopt with step 3 duplicate method, obtain temperature T _n+1the average Driving Torque T of lower correspondence _{em (Tn+1)}, core loss P _{fe (Tn+1)}, permanent magnetic steel eddy current loss P _{e (Tn+1)}with copper loss P _{cu (Tn+1)}, and import to again in three dimensional temperature field model, obtain temperature T when motor operation reaches stable by Fluent emulation _n+2, then by temperature T _n+2compare, so circulation is until satisfy condition.

Step 7: if meet formula (8) | T _n-T _n+1|≤σ the condition of convergence, then need to utilize Maxwell software emulation to go out motor and obtain at temperature T _n+1under average Driving Torque T _{em (Tn+1)}value, then judge average Driving Torque T _{em (Tn+1)}value whether equal the average Driving Torque T that step 3 obtains out _emvalue, if be not equal to, then need average Driving Torque T _{em (Tn+1)}with average Driving Torque T _em, the average Driving Torque of the motor that motor and traditional design method by the present invention's design design compares:

$K_T=\frac{T_{em\left(T_{n+1}\right)}}{T_{em}}---\left(9\right)$

In formula, K _tfor torque scale factor, the motor being expressed as traditional design affects the contrast ratio of front and back, T after excess temperature impact on the average Driving Torque of motor _emfor not considering the average Driving Torque that temperature impact and step 3 calculate, T _{em (Tn+1)}for considering that after temperature raises impact be the average Driving Torque that step 6 calculates.As average Driving Torque T _{em (Tn+1)}value equal average Driving Torque T _emvalue time, then can directly according to average Driving Torque T _{em (Tn+1)}determine the final size of motor.

Curve E see Fig. 4, Fig. 4 represents that the average Driving Torque that traditional design method and step 3 calculate, curve F represent the average Driving Torque calculated by step 6 under rear corresponding temperature.As can be seen from Figure 4, the motor of conventional method design, after excess temperature impact, is only 19.03Nm under its average Driving Torque.Therefore, the present invention introduces the torque scale factor K of motor _t, by the comparative analysis of Fig. 4, utilize formula (9) to obtain the K of magnetic flux switching external rotor electric machine _t=0.85.

According to torque scale factor K _t, amendment design can be carried out to traditional design motor.Switch in the process of optimization of external rotor electric machine at magnetic flux, the modifying factor of definition motor is k, namely k value is K _tinverse, and k=m ² ₁m ₂, wherein, m ₁and m ₂be respectively the diameter of stator bore D after optimization _{si (temp)}with stator pole embrace c _{s (temp)}correction factor.The motor stator internal diameter D after optimizing is obtained through following computing formula _{si (temp)}with stator pole embrace c _{s (temp)}, computing formula is as follows:

D _si(temp)＝m ₁D _si；c _s(temp)＝m ₂c _s；

D _si, c _sinitial diameter of stator bore and the stator pole embrace of the motor on traditional design basis respectively, wherein, the stator pole embrace c after optimization _{s (temp)}demand fulfillment condition 0.15<c _{s (temp)}<0.26.Work as K _twhen=0.85, k=1.18.

According to the diameter of stator bore D after optimization _{si (temp)}with stator pole embrace c _{s (temp)}and other parameter of motor, calculate the average Driving Torque T after optimization _{em (temp)}:

$T_{em\left(temp\right)}=\frac{\sqrt{2}{\mathrm{\&pi;}}^2}{4}{\mathrm{MD}}_{si\left(temp\right)}^2{c}_{s\left(temp\right)},$

In formula: $M=\frac{P_r}{P_s}{k}_s{k}_d{A}_s{l}_a{B}_{g\max }^{\&prime;}\mathrm{\&eta;}.$

Step 8: from formula (1) and (2), at the initial stator pole embrace c of optimization _sinevitably can cause initial rotor pole embrace c _rwith initial permanent magnetic steel polar arc c _pmchange.Therefore for ensureing that magnetic flux switches external rotor electric machine at final average Driving Torque T _{em (temp)}the basis run also needs initial rotor pole embrace c _rwith initial permanent magnetic steel polar arc c _pmbe optimized, meet following condition:

$\left\{\begin{array}{c}0.25\&le;c_{rn}\&le;0.39\\ 0.14\&le;c_{pmn}\&le;0.24\end{array}\right.---\left(10\right)$

In formula, c _rnfinal rotor pole arc coefficient, c _pmnit is final permanent magnetic steel polar arc.Thus the torque pulsation that magnetic flux switches external rotor electric machine can be reduced, improve the sine degree of no-load back electromotive force.

The result that the method for designing that the magnetic flux based on electric heating bidirectional coupled that the present invention proposes switches external rotor electric machine obtains as shown in Figure 5, after overtemperature impact, average Driving Torque curve its value as shown in the curve E of Fig. 4 of the motor of the target of traditional design method design is 19.03Nm, after method for designing used in the present invention, average Driving Torque after temperature impact is 22.8Nm, and torque pulsation is only 14.43%.It can thus be appreciated that, method proposed by the invention compared with traditional design method, designed by the motor that goes out more can meet the operation demand of modern electric automobile.

Claims (5)

1. based on a method for designing for the magnetic flux switching external rotor electric machine of electric heating bidirectional coupled, the power output P of selected motor ₂, rated power P, rated speed n, electric efficiency η, motor axial length l _a, stator poles p _s, rotor number of poles p _r, motor flux leakage coefficient k _d, skew slot factor k _s, motor lines load A _sand air gap flux density maximum B _gmaxthese parameters; Calculate the initial stator pole embrace c of motor _s, initial rotor pole embrace c _r, initial permanent magnet polar arc c _pm, initial stator rabbet polar arc c _slotwith initial diameter of stator bore D _si; Two-dimensional electromagnetic field model under utilizing Maxwell software to set up the ambient temperature of motor, utilizes Maxwell software emulation to go out the average Driving Torque T of motor _em, core loss P _fewith permanent magnetic steel eddy current loss P _e, and calculate copper loss P _cu, it is characterized in that further comprising the steps of:

A, set up three dimensional temperature field model in conjunction with Fluent software, by core loss P _fe, permanent magnetic steel eddy current loss P _ewith copper loss P _cuimport to three dimensional temperature field model, emulation obtains temperature T when motor operation reaches stable _n;

B, to calculate motor in temperature be T _ntime the residual magnetic flux density B that inscribes _r(T _n) and be HCJ H _ci(T _n), upgrade the permanent magnetic steel demagnetization curve under ambient temperature, obtain motor at temperature T _nunder permanent magnetic steel demagnetization curve, will upgrade after temperature T _nunder permanent magnetic steel demagnetization curve data feedback to described two-dimensional electromagnetic field model, obtain temperature T _nunder two-dimensional electromagnetic field model;

C, Maxwell software emulation is utilized to go out motor at temperature T _nunder average Driving Torque T _{em (Tn)}, core loss P _{fe (Tn)}, permanent magnetic steel eddy current loss P _{e (Tn)}and calculate copper loss P _{cu (Tn)}, by core loss P _{fe (Tn)}, permanent magnetic steel eddy current loss P _{e (Tn)}with copper loss P _{cu (Tn)}import in three dimensional temperature field model, obtain temperature T when motor operation reaches stable _n+1;

D, C.T T _nand T _n+1, when not satisfying condition | T _n-T _n+1| during≤σ, σ is temperature design precision, then upgrade temperature T _nunder permanent magnetic steel demagnetization curve, obtain motor at temperature T _n+1the permanent magnetic steel demagnetization curve of lower correspondence, then obtain temperature T _n+1the average Driving Torque T of lower correspondence _{em (Tn+1)}, core loss P _{fe (Tn+1)}, permanent magnetic steel eddy current loss P _{e (Tn+1)}with copper loss P _{cu (Tn+1)}, and again to import in three dimensional temperature field model, obtain motor and run temperature T when reaching stable _n+2, then by temperature T _n+2compare, so circulation is until satisfy condition; When satisfying condition | T _n-T _n+1| during≤σ, then first simulate motor at temperature T _n+1under average Driving Torque T _{em (Tn+1)}, then judge average Driving Torque T _{em (Tn+1)}whether equal average Driving Torque T _emif be not equal to, then first calculate torque scale factor and modifying factor then through formula D _{si (temp)}=m ₁d _siand c _{s (temp)}=m ₂c _srevise described initial diameter of stator bore D _siwith described initial stator pole embrace c _s, the diameter of stator bore D after being optimized _{si (temp)}with stator pole embrace c _{s (temp)}, m ₁and m ₂be respectively the diameter of stator bore D after optimization _{si (temp)}with stator pole embrace c _{s (temp)}correction factor, k=m ² ₁m ₂.

2., according to claim 1 based on the method for designing of the magnetic flux switching external rotor electric machine of electric heating bidirectional coupled, it is characterized in that: in step D, the diameter of stator bore D after being optimized _{si (temp)}with stator pole embrace c _{s (temp)}after, calculate the average Driving Torque T after optimization _{em (temp)}:

$T_{em\left(temp\right)}=\frac{\sqrt{2}{\mathrm{\&pi;}}^2}{4}{\mathrm{MD}}_{si\left(temp\right)}^2{c}_{s\left(temp\right)},M=\frac{P_r}{P_s}{k}_s{k}_d{A}_s{l}_a{B}_{gmax}^{\&prime;}\mathrm{\&eta;}.$

3., according to claim 2 based on the method for designing of the magnetic flux switching external rotor electric machine of electric heating bidirectional coupled, it is characterized in that: the average Driving Torque T after being optimized _{em (temp)}afterwards, to initial rotor pole embrace c _rwith initial permanent magnetic steel polar arc c _pmbe optimized: $\left\{\begin{array}{c}0.25\&le;c_{\mathrm{rn}}\&le;0.39\\ 0.14\&le;c_{\mathrm{pmn}}\&le;0.24\end{array}\right.,$ C _rnfinal rotor pole arc coefficient, c _pmnit is final permanent magnetic steel polar arc.

4., according to claim 1 based on the method for designing of the magnetic flux switching external rotor electric machine of electric heating bidirectional coupled, it is characterized in that: in step D, when judging average Driving Torque T _{em (Tn+1)}equal average Driving Torque T _emtime, then according to average Driving Torque T _{em (Tn+1)}determine the final size of motor.

5., according to claim 1 based on the method for designing of the magnetic flux switching external rotor electric machine of electric heating bidirectional coupled, it is characterized in that: in step D, the stator pole embrace c after optimization _{s (temp)}satisfy condition 0.15<c _{s (temp)}<0.26.