JP2014147269A - Stator and rotator for sr motor, and designing method for them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stator and a rotator for an SR motor, capable of enhancing the efficiency of the SR motor, and a designing method for them.SOLUTION: A designing method for a stator and a rotator of an SR motor, includes following steps: forming functions for the position of a reference SR motor rotator obtained from a finite element method magnetic field analysis and an inductance with regard to a coil current through a function such as least square method approximate expression; evaluating a motor efficiency when changing the coefficient of the function and applying a fixed segment excitation PWM voltage control method; defining a designing policy of a core shape for enhancing the motor efficiency on the basis of the evaluation; and determining the core shape meeting the designing policy. By employing the designing method, the stator and the rotator of the SR motor are designed to have such shapes: a shape of extending a stator yoke up to the upper part of the coil end in axial direction; a tooth length and a taper shape appropriate for the stator and the rotator; a stator yoke shape appropriate for a split core; and an appropriate overlapping shape of the stator and the rotator tooth in axial direction.

Description

  The present invention relates to an SR motor (Switched Reluctance Motor), and more particularly, to a core structure of a stator and a rotor and a design method thereof.

  SR motors have the advantage that the rotor core has a salient pole structure, the rotor does not have permanent magnets or windings, is mechanically robust, and is stable at high temperatures. It is attracting attention as a motor for hybrid vehicles. In addition, the SR motor is also characterized by being inexpensive because it does not use rare earth. However, since the motor efficiency is lower than that of a brushless DC motor, its practical application is delayed.

  As a technique for improving the motor efficiency of the SR motor, a core shape is designed on the assumption that a low iron loss material is used (see Non-Patent Document 1). However, since the design parameters targeted in the design of the core shape are limited to basic ones and changes in the axial direction of the core shape are not taken into account, it is difficult to say that the potential of the SR motor can be extracted.

  Although a structure in which the teeth of the stator / rotor core are overlapped using a dust core has been studied, it is premised on a dust core, so it is inherent to the dust core, such as insufficient mechanical strength and poor magnetic properties. Has not yet been put to practical use (see Non-Patent Document 2).

Patent Document 1 discloses a design example in which a silicon steel plate, which is a general material for electrical equipment, is used, the core shape is changed in the axial direction, and motor efficiency is improved.
In the motor manufacturing method disclosed in Patent Document 1, the shape of the stator / rotor core can be changed in the axial direction. Was extremely difficult.
With respect to such a problem, Patent Document 2 discloses a mold technique that can change the core shape in the axial direction by sliding a blade that punches out the teeth of the core.

JP 2005-348553 A Japanese Patent No. 4578460 (Japanese Patent Laid-Open No. 2008-67588)

Takaki Suzuki et al., “Development of high-efficiency switched reluctance motor”, IEEJ Transaction D, Vol. 126, No. 4, 2006 Seiji Ogasawara, Makoto Takemoto et al., “Development of a new structure of ferrite magnet motor for 50kW hybrid vehicles that does not use rare earths” [online] September 29, 2010, New Energy and Industrial Technology Development Organization, National University Corporation Hokkaido University, [Search on December 19, 2012], Internet <URL: http: //www.nedo.go.jp/news/press/AA5_0005A.html>

As described above, the motor efficiency of the SR motor varies depending not only on the core shape of the stator / rotor but also on the applied control method. Unlike the induction machines and synchronous machines for which mathematical models are established, SR motors have no established control method, and the influence of design parameters on motor efficiency has not been clarified. Child core design guidelines are difficult to make.
An object of the present invention is to provide a stator and a rotor of an SR motor that can improve the efficiency of the SR motor, and a design method thereof.

In order to solve the above-described problem, a method for designing the rotor and stator of the SR motor of the present invention includes:
Using a function such as an approximate expression by the least square method, the rotor position of the standard SR motor obtained by the finite element method magnetic field analysis and the inductance for the coil current are functionalized.
Evaluate the motor efficiency when applying the fixed section excitation PWM voltage control method when changing the coefficient of the function,
Based on the evaluation, the core shape design guidelines to improve motor efficiency were established,
A core shape that satisfies the design guideline is determined.
Further, the SR motor rotor and stator of the present invention have a shape in which the stator yoke is extended in the axial direction to the upper end of the coil end using the SR motor stator and rotor design method according to claim 1, The optimal teeth length and taper shape of the stator / rotor, the stator yoke shape suitable for the split core, and the optimal overlapping shape in the axial direction of the stator / rotor teeth. Features.
In the present invention, on the premise of increasing the space utilization factor, not only the cross-sectional shape of the stator / rotor core handled in the conventional design, but also the shape or stator in which the stator / rotor teeth alternately overlap in the axial direction. The invention includes a shape in which only the yoke is extended in the axial direction.
The present invention not only improves motor efficiency, but also improves output per unit volume and generated torque.

  According to the present invention, a motor efficiency comparable to that of a brushless DC motor can be obtained, and the characteristics of an SR motor that is mechanically robust and stable at high temperatures can be used as a drive source for an electric vehicle or the like. Can be used.

It is a flowchart which shows the flow of the optimization design method of the stator and rotor shape of SR motor which concerns on this invention. It is a graph which shows the SR motor model by inductance function expression. It is a graph which shows the motor efficiency of a 6/4 pole standard SR motor. It is a graph which shows the motor efficiency of a 12/8 pole standard SR motor. It is a graph which shows quantitative evaluation of the motor efficiency of a 6/4 pole SR motor. It is a graph which shows quantitative evaluation of the motor efficiency of a 12/8 pole SR motor. It is explanatory drawing of the change method of an inductance function. It is explanatory drawing of the state changed into the present invention conventionally from a stator core and coil end space. It is a comparison table of coil end space of 6/4 pole and 12/8 pole. FIG. 6 is a half cross-sectional perspective view showing an example in which a 6 / 4-pole core length is 114 mm and a rotor is provided with R. It is a half cross-sectional perspective view which shows the example which does not provide R in the rotor of 12/8 pole core length 126.8mm. It is explanatory drawing which shows the relationship between the teeth length of a stator and a rotor. It is explanatory drawing of the example of a change of the teeth width by this invention. It is explanatory drawing of the example of a change of the teeth taper angle by this invention. It is a graph which shows the relationship between a rotor position and an inductance in case the coil current in the case of 6/4 pole is 1A. It is a graph which shows the relationship between a rotor position and an inductance in case the coil current in the case of 6/4 pole is 100A. It is a graph which shows the relationship between a rotor position and an inductance in case the coil current in the case of 12/8 pole is 1A. It is a graph which shows the relationship between a rotor position and an inductance in case the coil current in the case of 12/8 pole is 100A. It is a chart which shows magnetic flux distribution at the time of high load of a standard core shape. It is a chart which shows magnetic flux distribution at the time of high load of the core shape which provided the taper angle. It is explanatory drawing which shows the location of a division | segmentation core junction part. It is a chart which shows magnetic flux distribution with a split core outer periphery core width of 5 mm. It is a chart which shows magnetic flux distribution with a split core outer periphery core width of 6 mm. It is a principal part enlarged chart which shows the gap analysis model of the joint surface of a split core. It is a graph which shows the influence on the inductance drop of the taper angle of a rotor tooth. It is explanatory drawing of a core back. It is a graph which shows the relationship between core back extension and an inductance drop. It is sectional drawing which shows the example of 2 steps | paragraphs of core unevenness | corrugations. It is sectional drawing which shows the example of 3 steps | paragraphs of core unevenness | corrugations. It is a split core sectional view of the high efficiency SR motor concerning an embodiment of the invention. It is a rotor sectional view of a high efficiency SR motor concerning an embodiment of the invention. It is a rotor cross section photograph of the high efficiency SR motor concerning an embodiment of the invention. It is a photograph of the rotor core of the high efficiency SR motor which concerns on embodiment of this invention. It is a photograph of the split core of the high efficiency SR motor rotor which concerns on embodiment of this invention. It is a photograph of the stator core of the high efficiency SR motor which concerns on embodiment of this invention. It is an external appearance photograph of the high efficiency SR motor concerning an embodiment of the invention. It is a graph of the static torque of a 6/4 pole SR motor. It is a graph of the static torque of a 12/8 pole SR motor. It is a graph which shows the rotation speed and output current characteristic of the high efficiency SR motor which concerns on embodiment of this invention. It is a graph which shows the motor efficiency and the motor output characteristic of the high efficiency SR motor which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
As described above, the switched reluctance motor (SR motor) is inferior in efficiency compared with the permanent magnet synchronous motor for the electric vehicle (EV). Therefore, the core shape is designed for the purpose of improving the motor efficiency of the SR motor for EV. The core shape is designed by evaluating the magnetic efficiency by the finite element method and the motor efficiency by transient simulation.

In the present embodiment, the influence of the SR motor inductance curve on the motor efficiency is first examined by a transient simulation, and a design guideline for the core shape is set based on the examination result.
Next, based on the design guideline, the core shape is designed by evaluating the inductance curve calculated by the magnetic field analysis by the finite element method.
Finally, an SR motor using the designed core shape will be prototyped, the motor efficiency will be measured by actual machine tests, and the improvement effect of the motor efficiency will be discussed.

1. Design Guidelines In order to optimize the core shape of the SR motor, it is necessary to repeat the characteristic calculation of the SR motor including the motor efficiency while changing the core shape.
Magnetic field analysis by the finite element method requires a lot of analysis time. Therefore, the design is performed based on the flowchart shown in FIG.

In the block of the basic design 100 of the core shape in FIG. 1, the SR motor model 110 represented by the inductance function, the transient analysis 120 using the SR motor, the mechanical system, and the angular model of the inverter, the speed torque characteristic and the operating efficiency 130 The design guideline for the core shape is determined by repeating the transient simulation using each process and examining the relationship between the core shape and the motor efficiency.
After determining the design guideline for the core shape in block 100, in block 200, the core shape of the rotor / stator is designed to meet the design guideline using magnetic field analysis by a three-dimensional finite element method (FEM).

FIG. 2 shows an SR motor model 110 expressed by an inductance function.
The FEM magnetic field analysis result is given as the number of magnetic flux linkages using the rotor position and phase current as parameters. Inductance is obtained by dividing the number of flux linkages by the phase current.
First, using the FEM magnetic field analysis result for the standard core, an approximate expression by the least square method of the inductance with the rotor position as a variable is derived for each phase current. This approximate expression is a high-order polynomial with the rotor position as a variable, and is used as an inductance function.
The coefficient a (n) varies depending on the magnitude of the phase current, and is calculated by the least square method using the FEM magnetic field analysis result for each phase current. The order n is determined to be a value around 10 by evaluating an error from the analysis result.
Using the inductance function L (θ), the torque, magnetomotive force, and flux linkage number at each operating point are calculated and tabulated, so that a torque table and a magnetomotive force table serving as a standard SR motor model can be generated.
If a change expected from the change of the core shape is given to the inductance function L (θ) of the standard SR motor, an SR motor model composed of a torque table and a magnetomotive force table corresponding to the change is automatically generated. it can. The change to be given is expressed by a function k (θ) having the rotor position as a variable. By multiplying the function k (θ) and the inductance function L (θ), an inductance function considering the change in the core shape can be obtained.
The torque table and magnetomotive force table of the SR motor model considering the change in the core shape can be generated in the same manner as the standard SR motor.

FIG. 3 shows the motor efficiency of the 6/4 standard SR motor. This is a calculation result of the motor efficiency in the transient simulation using MATLAB Simulink. As a calculation condition, a control system is assumed in which the generated voltage is adjusted by battery voltage 96V, fixed section excitation with a constant excitation start / end angle, and pulse width modulation (PWM) voltage control.
FIG. 4 shows the motor efficiency of a 12/8 standard SR motor calculated under the same conditions.
3 and 4 show the distribution of the motor efficiency for each operating point expressed by the load torque T _L and the rotation speed N _r . By giving a change in the core shape and calculating a similar motor efficiency distribution, the influence of the change in the core shape on the motor efficiency can be quantitatively evaluated.

  FIG. 5 shows a method for changing the inductance function. Here, in order to obtain a guideline for designing the core shape, the inductance was changed without mentioning the possibility of realization, and the influence on the motor efficiency was considered. The head change (1) increases the maximum value of the inductance, and the head change (2) decreases the minimum value of the inductance, so that the inductance difference between the opposing and non-opposing positions is designed to be large. . The shape change (1) assumes a case where the inductance is designed to change greatly in the second half, and the shape change (2) assumes a case where the inductance is designed to change greatly in the first half. Phase change (1) and phase change (2) assume an asymmetrical stator and rotor.

FIG. 6 shows a quantitative evaluation of the motor efficiency of the 6/4 pole SR motor. The operating area (area) of the standard core of the 6/4 pole SR motor normalizes the operating area of each shape change. The head change (1) corresponds to I, and the head change (2) corresponds to II. The shape change (1) corresponds to III, and the shape change (2) corresponds to IV. Phase change (1) corresponds to V and phase change (2) corresponds to VI. Above each bar is the average efficiency and the rise point from the standard core.
FIG. 7 shows a quantitative evaluation of the motor efficiency of the 12 / 8-pole SR motor. The operating area (area) of the standard core of the 6/4 pole SR motor normalizes the operating area of each shape change. The head change (1) corresponds to I, and the head change (2) corresponds to II. The shape change (1) corresponds to III, and the shape change (2) corresponds to IV. Phase change (1) corresponds to V and phase change (2) corresponds to VI. Above each bar grab shows the average efficiency and the rise point from the standard core.
Comparing the operation area of the 6 / 4-pole SR motor and the 12 / 8-pole SR motor, the operation area of the 12 / 8-pole SR motor is 1.5 times. The effect of improving the efficiency of each shape is the same in the 6/4 pole SR motor and the 12/8 pole SR motor. The drop change (1) is the most effective, followed by the drop change (2) and the shape. Change (1) is effective.

Table 1 shows changes in motor efficiency when the change in inductance function shown in FIG. 5 is applied to the SR motor model. It was found that the head change (1) is the most effective, followed by the head change (2), the shape change (1), and the phase change (1) in this order. Since the spatial differential value of the inductance increases as the drop increases, it can be said that this is effective from the viewpoint of the SR motor torque generation principle. The reason why the shape change (1) and the phase change (1) are effective is thought to be that the fixed section excitation PWM voltage control method is applied as the excitation method, and that the current is thus distributed on the average. The shape change and the phase change need to be examined even when the variable section excitation is applied as the excitation method, so the head change (1) is designed with the first priority.

2. Core Design (1) Core Extension As shown in FIG. 8, there is a space between the stator core and the coil end. If this space is filled with the core and the cross section of the core is increased, the inductance is increased and the efficiency is improved. In addition, by changing from the 6/4 pole to the 12/8 pole, the coil cross-sectional area is reduced and a coil end space is generated, so that the core can be further extended.

  FIG. 9 shows a comparison of the coil end space between the 6/4 standard SR motor and the 12/8 standard SR motor. Based on the 6/4 standard SR motor, the 12/8 standard SR motor has a large 12.8 mm coil end space. If this coil end space can be used effectively, it can be said that the 12/8 standard SR motor has a higher possibility of improving the motor efficiency than the 6/4 standard SR motor.

  FIG. 10 shows a three-dimensional analysis model of a 6 / 4-pole SR motor having a core length of 114 mm and a curvature of the stator / rotor teeth end along the coil end. Table 2 shows the effect of changing the 6/4 pole core length. By matching the stator teeth end to the coil end shape, the core length can be further extended, so that the inductance at the opposing position increases. Further, by matching the rotor teeth end to the shape of the stator teeth end, the inductance at the non-opposing position is slightly reduced, but the inductance at the opposing position is also reduced, so that the inductance difference does not increase. Therefore, the curvature is provided only at the end of the stator teeth.

  FIG. 11 shows a three-dimensional analysis model of a 12 / 8-pole SR motor having a core length of 126.8 mm and a curvature of the stator / rotor teeth end along the coil end. Table 3 shows the effect of changing the 12/8 pole core length.

  Comparing the standard core inductance comparison magnifications of the 6/4 pole and the 12/8 pole, the 12/8 pole can greatly extend the stator core, so that the inductance difference is greatly increased.

(2) Ratio of Stator / Rotor Teeth Length As shown in FIG. 12, the ratio between the stator teeth length and the rotor teeth length was changed to determine the inductance difference. Tables 4-1 and 4-2 show the analysis results for changing the ratio of the stator / rotor teeth length of the 6 / 4-pole SR motor.

  Tables 5-1 and 5-2 show the analysis results for changing the ratio of the stator / rotor teeth length of the 12 / 8-pole SR motor. The inductance at the facing position is not affected by the tooth tip position, and there is no change in any coil current. However, when the stator teeth length is shortened and the rotor teeth length is lengthened, the inductance at the non-facing position decreases, and the inductance difference increases. These trends are observed for both 6/4 and 12/8 poles. As long as the coil space can be ensured, a shorter inductance tooth length and a longer rotor teeth length result in a larger inductance drop.

(3) Core teeth shape It was examined which of the shape in which the core teeth width shown in FIG. 13 was widened and the taper shape shown in FIG. 14 were effective in increasing the inductance drop. In order to equalize the amount of iron used, the cross-sectional areas of both shapes are made equal.
15-1 and 15-2 show inductance curves in the case of the coil current 1A and 100A of the 6/4 pole SR motor, and Tables 6-1 and 6-2 show the case of the coil current 1A and 100A. Inductance drop in the case of.

  FIGS. 16-1 and 16-2 show inductance curves in the case of the coil current 1A and 100A of the 12 / 8-pole SR motor, and Tables 7-1 and 7-2 show the 12 / 8-pole SR motor. The inductance difference between the case of the coil current 1A and the case of 100A is shown. When the load is low (coil current 1A), the shape with the expanded tooth width increases the inductance at the opposing position, and the shape with the taper angle is close to the standard. When the load is high (coil current 100 A), the shape with the expanded tooth width increases the inductance at the non-facing position, and the shape with the taper angle does not increase the inductance at the non-facing position, but increases the inductance at the facing position. . The effect of changing the tooth shape is greater for the 12/8 pole than for the 6/4 pole.

  FIG. 17 shows the magnetic flux distribution of the standard core shape at high load. FIG. 18 shows a magnetic flux distribution at a high load of a core shape having a taper angle. In FIG. 18, the coil shape is changed in accordance with the taper angle, but the coil cross-sectional area is the same as FIG. By providing the taper angle, the magnetic saturation in the teeth is reduced, the magnetic flux easily flows, and the magnetic flux of the entire core is increased.

(4) Number of poles Table 8 summarizes the improvement effect on the inductance drop based on the analysis results from (1) to (3). There is no difference between the stator / rotor teeth length ratio and the core teeth shape between the 6 / 4-pole SR motor and the 12 / 8-pole SR motor, but the core extension improvement effect is 12 / 8-pole SR. The motor is larger. Henceforth, we will focus on the 12 / 8-pole SR motor and examine it.

(5) Divided core In the divided core, the concentrated winding coil can be manufactured independently of the core, so that the coil space factor is improved and the copper loss is reduced. However, as shown in FIG. 19, since the width of the split core junction is narrowed, there is a possibility of magnetic saturation in the vicinity. In order to increase the coil space within the range where magnetic saturation does not occur, the width of the split core junction is gradually reduced under the condition of the coil current of 100 A, and the optimum width is obtained. Tables 9-1 and 9-2 show the effect of the split core junction width on the inductance drop. When the width of the standard laminated core is narrowed by -6 mm, the inductance drop decreases rapidly.

  FIG. 20 shows a magnetic flux distribution with a width of −5 mm at the split core joint, and FIG. 21 shows a magnetic flux distribution with a width of −6 mm at the split core joint. The BH curve of the core material used in the analysis becomes saturated when the magnetic flux is 1.69 [T] or more. The magnetic flux at the location indicated by the circle in FIG. 20 is approximately 1.45 [T]. It can be confirmed that the magnetic flux is saturated at about 1.73 [T] when the magnetic flux in the portion indicated by a circle in FIG. 21 is viewed.

  Therefore, the width of the split core joint portion is set to be -5 mm narrower than the standard width of the core joint portion. Coil space is increased by reducing the width of the split core joint. By effectively using the coil space and increasing the taper angle, the flow of magnetic flux is further improved and the inductance drop is increased. As shown in Table 10, when the taper angle is increased, the inductance drop increases, but the coil space becomes narrow and the coil cannot be wound. Therefore, the taper angle is selected to be 6 degrees.

(6) Gap of split core joint surface As shown in FIG. 22, it is assumed that a gap occurs on the joint surface of split cores, and the effect of the gap on the inductance is confirmed. Since the joints of the split cores that are actually manufactured are complex, they were calculated by a simple two-dimensional analysis. Table 11 shows the split core interface gap and inductance. When the joint surface gap is 0.1 mm, the inductance is rapidly reduced to prevent the flow of magnetic flux. When assembling the split core with an actual machine, it is necessary to devise so as not to generate a gap in the joint surface of the split core.

(7) Rotor teeth taper angle Unlike the stator, the rotor does not take into account the coil space, and the taper angle can be freely set, so the taper angle is changed every 2 degrees from 0 degrees to 18 degrees. Find the inductance drop. FIG. 23 shows the influence of the taper angle of the rotor teeth on the inductance drop. The inductance drop increases up to a taper angle of 6 degrees, but is saturated around 8 degrees. Therefore, the taper angle of the rotor teeth is selected to be 8 degrees.

(8) Core Back As shown in FIG. 24, by providing the core back, the cross-sectional area of the stator yoke including the core joint portion increases, so that the inductance difference increases. FIG. 25 shows the relationship between core back extension and inductance drop. The inductance drop increases by extending the core back. In order to make it the same size as the standard motor, the core back extension is 10 mm and the both end faces are 20 mm. At this stage, the yoke shaft length of the stator core becomes +50 mm by adding the core back extension +20 mm to the core extension +30 mm due to the multipolarization as compared with the standard core.

(9) Three-dimensional gap structure As shown in FIG. 26, the gap between the stator and rotor cores is made uneven so that the overlapping surface between the cores increases, thereby increasing the inductance. First, select the number of bumps. FIG. 26 shows the shape when there are two uneven portions, and FIG. 27 shows the shape when there are three uneven portions.
In the above (2), since the upper limit of the change in the tip position of the core teeth is set to 3 mm, the change in the tip position of the teeth is set to a maximum of 3 mm in both core shapes. Table 12 shows the results of the number of core irregularities. When the coil current is 100 A (when the load is high), the inductance drop between the two uneven portions is larger than the three uneven portions.

  As the number of stages increases, the width of the uppermost stage of the number of stages gradually narrows, and it is considered that the magnetic flux is saturated at that portion.

  Next, the optimum combination of unevenness and the combination of unevenness step width are selected. As a comparison object, Table 13 shows the results of the core shape using only the 0th stage and the core shape using only the second stage without providing irregularities.

  Table 14 shows the results of the uneven width 2 mm, Table 15 shows the results of the uneven width result 4 mm, and Table 16 shows the results of the unevenness 8 mm. The narrower the unevenness width is, the more unevenness can be provided, and the overlapping surface of the core can be increased correspondingly, so that the inductance difference at low load increases. However, since the uneven width is narrow, the inductance drop decreases due to the effect of magnetic saturation at high loads. The wider the unevenness width, the smaller the number of unevennesses, the fewer overlapping surfaces, and the decrease in inductance drop at low load. However, since the uneven width is wide, it is not affected by magnetic saturation at high loads.

  Furthermore, the pyramid type in which the uneven shape is 0 step → 1 step → 2 step → 1 step → 0 step and the groove type inductance drop in which the 0 step → 2 step → 0 step is compared are compared. Since the groove type can provide more irregularities than the pyramid type, the overlapping surface of the core can be obtained, and the inductance drop at low load increases.

  However, at high loads, the inductance drop decreases due to the strong magnetic saturation. A well-balanced groove type with an uneven width of 4 mm is selected.

(10) Gap length The amount of increase in the inductance drop when the gap length is reduced from 0.5 mm to 0.3 mm is examined. Table 17 shows the result of changing the gap length under the condition using only the 0th stage of the stator core, and Table 18 shows the result of changing the gap length under the condition of using only the 2nd stage of the stator core. An inductance drop increases by narrowing the gap length by 0.2 mm. The effect is greater when only the second stage of the stator core is used than the 0th stage of the stator core.

3. High efficiency SR motor A high-efficiency SR motor was prototyped based on the core design described in. FIG. 28 shows a stator core cross section, and FIG. 29 shows a rotor core cross section. FIG. 30 shows a prototype rotor core. FIG. 31 shows the stator core. Twelve stator split cores are required for the manufacture of the stator core. FIG. 32 shows the appearance of the completed high-efficiency SR motor.

(1) Actual machine verification of static torque The static torque is measured by an actual machine test, and the static torque obtained by finite element method magnetic field analysis is verified. FIG. 33 shows the static torque of the 6/4 pole SR motor.
FIG. 34 shows the static torque of the 12/8 pole SR motor. The static torque was obtained by analysis with three types of core materials, but the value approximated the measured static torque.

(2) Efficiency of high-efficiency SR motor Table 19 shows the performance table of the standard SR motor and the high-efficiency SR motor. Compare the characteristic test results of standard SR motor and high efficiency SR motor. FIG. 35 shows the number of rotations and output current, and FIG. 36 shows the results of motor efficiency and motor output.

4). Summary The basic design of the core shape of the SR motor was performed, and the design guidelines for improving the motor efficiency were summarized. In accordance with the design guideline, optimization design of the number of core poles and shape by magnetic field analysis was carried out, and the number of core poles and core shape that improved the motor efficiency by 5% or more were determined. An SR motor was prototyped by producing a core mold with the determined number of core poles and core shape, and a motor efficiency improvement of 5% or more was confirmed in an actual machine test.

  The present invention can be applied to a system that uses electric motor power, and can be used for a drive motor of an electric vehicle, for example.

Claims (4)

Using a function such as an approximate expression by the least square method, the rotor position of the standard SR motor obtained by the finite element method magnetic field analysis and the inductance for the coil current are functionalized.
Evaluate the motor efficiency when applying the fixed section excitation PWM voltage control method when changing the coefficient of the function,
Based on the evaluation, the core shape design guidelines to improve motor efficiency were established,
A method of designing a stator and a rotor of an SR motor, wherein a core shape that satisfies the design guideline is determined.   Using the SR motor stator and rotor design method according to claim 1, a shape in which the stator yoke is extended in the axial direction to the upper part of the coil end, an optimal teeth length and taper shape of the stator / rotor, and division SR motor stator and rotor designed to have a stator yoke shape suitable for the core and an optimal overlapping shape in the axial direction of the stator / rotor teeth.   3. The stator and rotor of an SR motor according to claim 2, wherein only the stator yoke is extended by about 10 mm in the axial direction from the stator teeth.   3. The stator and rotor of an SR motor according to claim 2, wherein the teeth of the stator and the rotor are alternately overlapped at an interval of about 4 mm in the axial direction.