JP2012244683A - Method of selecting motor iron core material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform selection of an iron core material that can minimize a total motor iron loss over all time zones of a pattern with accuracy, with efficiency and with ease in the case that such a pattern that temporally passes through many operation points as motor operation points is obtained.SOLUTION: In a method of selecting a motor iron core material, because material characteristics determination at a weighted average representative operation point which adopts a function with a specific weight can be alternatively used, selection of an iron core material which makes a motor performance over all time zones of a pattern be the best, which cannot be achieved by conventional material selection by material characteristics determination at a maximum output operation point and a steady output operation point, can be performed with accuracy, with efficiency and with ease.

Description

  The present invention relates to a method for selecting a motor core material suitable for selecting a motor core material having a pattern in which a large number of operating points pass through as a motor operating point.

In the technical field of motors, induction motors have been widely used because of their simple and robust structure, and the operating conditions have mainly been constant speed operation at commercial frequencies. However, in recent years, with the growing concern about environmental problems and energy saving, motor-efficient operation has been aimed at.
In addition, motors for home appliances, air conditioners, etc. were once normally operated at a constant speed at a commercial frequency, but now, variable speed operation using an inverter power supply is common sense. As described above, the motor operating point has been mainly a constant operating point operation as in the case of a constant speed operation using a commercial frequency. However, due to the widespread use of variable speed operation using an inverter power supply, there are a large number of operating points. It has become an operating condition that goes through time.

Furthermore, nowadays, electric motors are also used in hybrid vehicles and electric vehicles. Since automobiles frequently repeat acceleration and deceleration, the operating point of a motor used particularly in the automobile field changes with time, and many operating points pass with time.
Here, the procedure for selecting the core material with the lowest motor iron loss is to first determine the operating point for material performance determination according to the specifications of the motor, and then calculate the motor characteristics at that operating point by simulation or actually The procedure is such that the motor is prototyped and evaluated, and the material with the best characteristics is selected (see, for example, Patent Documents 1 to 3).

  In a motor that is in a steady operation, the operating point of the steady operation is used as an operating point for material performance determination. Further, in a motor operated at a variable speed, for example, a motor for an air conditioner, the maximum output operating point (rapid cooling operation) and the steady output operating point (steady cooling operation) are often used as the operation points for material performance determination. Is customary.

JP-A-2005-312155 JP 2004-183002 A JP-A-8-240513 JP-A-8-248104

  However, in the case of the automobile field, for example, performance evaluation is performed on a specific traveling pattern (for example, a traveling pattern called a 10-15 mode or a JC08 mode). Since these are assumed / simulated when actually traveling in an urban area or the like, for example, when a hybrid vehicle is considered, traveling in this mode repeats acceleration / deceleration multiple times and steady traveling. Therefore, the motor operating point has a pattern that passes through a large number of operating points in time.

  Therefore, even if the core material that minimizes the motor iron loss at the operating point is selected as the operating point for determining the material performance, as in the past, the maximum output operating point or the steady output operating point is selected. As a result, there is a problem that the motor material is not selected so that the fuel consumption that is most important as a hybrid vehicle is the best.

  For example, in Patent Document 4, a motor performance test is performed using a motor test apparatus capable of driving a motor in accordance with driving mode data of an automobile. However, in order to carry out such a test, as detailed in Patent Document 4, it is necessary to perform complex motor drive control and load control, and a test apparatus for realizing this is complicated and expensive. It must be something special. Furthermore, as the driving mode of the automobile becomes more complicated, the motor test becomes more complicated and takes a long time.

  Therefore, the present invention has been made paying attention to such problems, and in the case of a pattern in which a large number of operating points pass in time as motor operating points, the motor characteristics over the entire pattern time zone. It is an object of the present invention to provide a method for selecting a material for a motor core capable of accurately and efficiently selecting an iron core material that can achieve the best performance.

  In order to solve the above-described problems, the present invention provides a motor operating point specified by one torque and one rotation speed via a plurality of points as time passes in an operating point space defined by torque and rotation speed. A method for selecting a material for a motor core used in driving conditions, the first step of dividing a region surrounded by a motor maximum torque curve in the operating point space into a plurality of box regions, and the motor operating point The operation continuation time for each motor operation point traced according to the operation elapsed time is obtained, and which of the plurality of box regions defined in the first step is determined for each motor operation point corresponding to the operation continuation time. The second step of determining whether to enter the region and the sum of the operation durations of the motor operating points entering each of the box regions are taken, and the value of the sum is operated for all motors. A third step for determining the weight ratio of the box region to the middle, a fourth step for determining the representative operating point for each box region and determining the motor characteristics at the representative operating point for all the box regions, A fifth step of obtaining a weighted average motor characteristic over the entire motor operation time by dividing the sum of the products of the weight ratio for each box area and the motor characteristics by the sum of the weight ratios for each box area; And a sixth step of selecting a material to be adopted by obtaining a weighted average motor characteristic based on the first to fifth steps and comparing them with each other. .

Here, in the method for selecting a material for a motor core according to the present invention, the number of motor operating points is larger in the number of motor operating points than the number of motor operating points is smaller in accordance with the number of motor operating points in the operating point space. It is preferable to divide the area to be divided into box areas so as to be narrow.
Moreover, in the method for selecting a material for a motor core according to the present invention, it is preferable that the representative operating point determined for each box region in the fourth step employs the center of gravity weighted by the operation duration time of each motor operating point. .

  According to the method for selecting a material for a motor core according to the present invention, instead of the conventional material performance determination at the maximum output operating point or the steady output operating point, the weighted average motor characteristic adopting a function of a predetermined weight is used. Since the material characteristics can be substituted, it is possible to select an iron core material that can achieve the best motor characteristics over the entire pattern time zone that cannot be achieved by conventional material selection with high accuracy and efficiency.

  As described above, according to the present invention, as a method of selecting a core material that provides the best average motor performance over the entire pattern time zone, in the case of a pattern that passes through many operating points in time as a motor operating point, Instead of the conventional material characteristic determination at the maximum output operating point and the steady output operating point, it can be replaced by the material characteristic determination at the weighted average representative operating point adopting a specific weight function. It is possible to select an iron core material that has the best motor performance over the entire time zone of the pattern, which cannot be achieved by selection, with high accuracy and efficiency.

  Compared to the case where a motor is actually prototyped and evaluated using a motor test device over the entire driving pattern, the time, labor and cost of the prototype, and the trouble of introducing and using a complicated and expensive motor test device Therefore, the motor core material can be selected quickly and easily at low cost.

It is a figure explaining the material selection apparatus (computer) for motor cores which performs the material selection process for motor cores which concerns on the selection method of the material for motor cores of this invention. It is a figure which shows an example (JC08 mode) of the driving modes used as the pattern which passes through many operating points in time as a motor operating point. It is a figure which shows the example which divided | segmented the area | region enclosed by a motor specification (motor maximum torque curve) into a some box area | region with respect to an example (JC08 mode) of the driving mode of FIG. It is a flowchart explaining the material selection process for motor cores which concerns on this invention. It is a figure which shows the pattern which passes many operating points in time as a motor operating point used in the Example. It is a graph of the test result which calculated | required the average value over the whole drive time of three motors shown in an Example. It is a graph of the result of having calculated the motor loss in the maximum output operation point of the three motors shown in an Example by numerical simulation. It is a figure which shows the state divided into the box area | region with respect to the pattern shown in FIG. FIG. 9 is an enlarged view of a part of the box area of FIG. 8. It is a graph which shows the calculation result of an average motor loss (when the center point of a box area | region is selected as a representative operating point). It is a graph which shows the calculation result of average motor loss (when the gravity center of the operation point contained in each box is selected as a representative operation point). 12 is a graph showing the results of FIGS. 6, 10, and 11 collectively.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate.
As shown in FIG. 1, a motor core material selection apparatus 10 includes a CPU 30 that controls operations and the entire system based on a predetermined control program, and a storage device that stores a control program for the CPU 30 in a predetermined area in advance. 42, ROM 32, RAM 34 for storing data read from storage device 42, ROM 32, etc., and computation results required in the computation process of CPU 30, and data for input device 40, storage device 42, display device 44, etc. Are connected to each other via a bus 39 which is a signal line for transferring data so that data can be exchanged. Then, a predetermined program stored in a predetermined area of the CPU 30, the storage device 42 and the ROM 32 is activated, and the following motor core material selection processing is executed according to the program.

  By the way, when a hybrid vehicle is considered as an example, the actual vehicle traveling is repeated a plurality of times of acceleration / deceleration and steady traveling, so that the motor operating point has a pattern of passing many operating points in time. For example, the locus of the motor operating point of a certain hybrid vehicle when traveling in a traveling mode called a JC08 mode, in which a performance test of an automobile will be performed, is as shown in FIG.

  In the motor core material selection process according to the present invention, when the process is executed, first, the process proceeds to step S1 in FIG. 4 and is designated by the torque T (N · m) and the rotation speed N (rpm). The operating point (N, T) passes through a plurality of operating points as A1 (N1, T1), A2 (N2, T2),..., An (Nn, Tn) as time passes. 3, the region (Tmax) surrounded by the motor maximum torque curve in the operating point space defined by the torque T and the rotational speed N is divided into a plurality of box regions B1, as shown in FIG. A process of dividing into B2,..., Bm is performed (first step).

  Next, the process proceeds to the following step S2, and the durations during which the motor is operated at each operating point obtained by following the operating point (N, T) according to the elapsed operation time are denoted by Δt1, Δt2,. , It is determined which of the plurality of box areas B1, B2,..., Bm defined in FIG. Process). Next, the process proceeds to step S3, and the total sum Wk = Δtk1 + Δtk2 + of each operation duration time Δtk1, Δtk2,..., Δtk1 of the operation points Ak1, Ak2,. ... + Δtkl is taken and the value Wk is set to the weight ratio of the kth box with respect to the total motor operating time (third step).

  Next, the process proceeds to step S4, in which a representative operation point is determined for each box region, and the material motor performance that is the selection target at the representative operation point is numerically simulated for the material that is the selection target. Find (fourth step). As the representative operation point, the center of gravity Akg (Nkg, Tkg) of the operation points Ak1, Ak2,. Then, the motor characteristic (motor iron loss or motor efficiency) at the gravity center Akg of the operating point is obtained by numerical simulation, and the value is set as the representative performance value Pk of the box area. Thereafter, the same calculation is sequentially performed on all the box areas.

  After performing the same calculation for all the box areas sequentially, the process proceeds to step S5, where the sum of the products of the weight ratio Wk of each box area and the motor representative performance value Pk is calculated as the weight ratio for each box area. Dividing by the total sum, Pav = (P1 · W1 + P2 · W2 +... + Pm · Wm) / (W1 + W2 +. .

Next, the process proceeds to step S6, and the numerical core simulation is repeated by sequentially changing the iron core material to be selected. That is, if there is a next iron core material to be selected (Yes), the next iron core material is selected in step S7, and the process returns to step S4. On the other hand, if there is no next iron core material to be selected (No), the process proceeds to step S8.
That is, if the above process (steps S1 to S7) is performed for each iron core material to be selected, the process proceeds to step S8, where the weighted average motor characteristics are obtained and the iron core materials are compared with each other. Then, select the core material that showed the best motor performance (sixth step). Here, at the time of selection in step S8, when the motor efficiency is regarded as important as the motor characteristics (motor performance), a material that maximizes the motor efficiency may be selected, and when the motor iron loss is regarded as important. For this, a material that minimizes the motor iron loss may be selected.

  As described above based on the embodiment, according to the method for selecting a material for a motor core, the motor operating point (N, T) specified by the torque T and the rotational speed N passes through a plurality of points as time passes. As a method of selecting the core material that provides the best average motor performance over the entire rotation time pattern, it can be replaced by material performance judgment based on weighted average motor characteristics using a specific weight function. It is possible to select an iron core material with the best motor characteristics over the entire pattern time zone, which cannot be achieved by material selection based on material characteristics determination at the output operation point and the steady output operation point, with high accuracy and efficiency. In addition, this invention is not limited to the said embodiment, Of course, a various deformation | transformation is possible if it does not deviate from the meaning of this invention.

  For example, in the above embodiment, the representative operating point determined for each box area in the fourth step has been described as an example in which the center of gravity of the motor operating point weighted by the operating duration of each operating point is adopted. The center of gravity of each box area itself may be used as the representative operating point of the box area. However, in order to select an iron core material with the best motor characteristics with high accuracy, it is preferable to employ the center of gravity of the motor operating point obtained by weighting the representative operating point with the operation duration time of each operating point.

  Further, for example, in the above-described embodiment, as a method of dividing into box regions, an example in which dividing lines are set at equal intervals along the X axis and the Y axis is shown as shown in FIG. In addition, various methods for dividing into box regions can be employed. For example, the dividing lines may be set obliquely with respect to the X axis and the Y axis, or the dividing lines can be set at unequal intervals. In particular, in the present invention, according to the number of motor operating points in the space in which the motor operating point (N, T) moves, the number of motor operating points is divided compared to the number of motor operating points. It is preferable to divide so that the box area to be narrowed. Such a configuration is more suitable for accurately and efficiently selecting an iron core material that has the best motor characteristics.

  In the present embodiment, a motor is created in which the motor operating point per second is used under the conditions shown in FIG. Three types of electromagnetic steel plates a, b, and c having a thickness of 0.35 mm shown in Table 1 were prepared. A permanent magnet type DC brushless motor iron core having a stator outer diameter of 156 mm, a rotor diameter of 105 mm, and 12 poles was prepared by wire cutting in total using three materials a to c. As the magnet, an Nd-based sintered magnet was used so that high torque characteristics were obtained. The respective motors were designated as motor a, motor b, and motor c.

  Sequentially perform performance tests on three motors manufactured by inputting a program to drive the motors with the operating point series shown in FIG. 5 to the command device that controls the motor drive inverter and brake motor of the motor performance test device. The average value of motor loss over the entire driving time was obtained. As shown in the test results in FIG. 6, the average motor loss becomes lower in the order of motor b <motor a <motor c, and the iron loss of the motor using the material having the lowest iron loss W15 / 50 is necessarily minimized. The results were not limited. We will investigate whether the experimental results related to the selection of the core material that minimizes the average value of motor loss over the entire drive time can be reproduced.

  The operating point having the maximum output in the operating point group shown in FIG. The motor loss at the maximum output operating point was calculated by numerical simulation as was done conventionally. As a result, as shown in FIG. 7, the motor loss decreased in the order of motor a <motor b <motor c, and became equal to the low order of the iron loss W15 / 50 of the used material, but the material order of FIG. 6 was reproduced. Not done. Thus, it was confirmed that even if the material was selected based on the characteristic evaluation at the maximum output operating point, the iron core material that minimizes the average value of the motor loss over the entire driving time was not necessarily selected.

  Next, the method of the present invention will be considered. First, the operating point area of the motor was divided into equally spaced boxes as shown in FIG. 8 (first step). Next, the number of operating points contained in each box was counted for each box (second step). Since the motor operating point is taken every second, the duration Δt of each operating point is considered to be 1 second, and the number of operating points counted for each box is determined as the weight ratio of the box (first 3 steps).

The center point of the box area is selected as the representative operation point determined for each box. As an example, FIG. 9 is an enlarged view of portions of box A and box B shown in FIG. 8 for easy understanding. In the same figure, the center point of the box A is a rotation speed of 1650 rpm and a torque of 1.5 N · m, and the motor loss when operating at a rotation speed of 1650 rpm and a torque of 1.5 N · m was calculated by numerical simulation. Similarly, the center point of the box B has a rotation speed of 1650 rpm and a torque of 0.5 N · m, and the motor loss when operated at a rotation speed of 1650 rpm and a torque of 0.5 N · m was calculated by numerical simulation.
In the same manner, for each box, the center point of the box area and the motor loss with the center point as the operating point were calculated by numerical simulation (fourth step).

Further, the center of gravity of the operation point included in each box is selected as the representative operation point determined for each box. As shown in FIG. 9, the box A includes seven operating points, and calculating the center of gravity of these points yields a rotational speed of 1649 rpm and a torque of 1.77 N · m. The motor loss when operating at 1.77 N · m was calculated by numerical simulation.
Similarly, the box B includes nine operating points, and calculating the center of gravity of these points yields a rotational speed of 1675 rpm and a torque of 0.45 N · m. Therefore, the rotational speed of 1675 rpm and a torque of 0.45 N · m are obtained. The motor loss when operated with the motor was calculated by numerical simulation.
In the same manner, the center of gravity of the operating point included in each box was determined for each box, and the motor loss when operating with that point as the operating point was calculated by numerical simulation (fourth step). Of course, it is not necessary to perform the above-described series of processing for a box that does not include any operating point in each box area shown in FIG.

A value obtained by multiplying the motor loss at each box representative point obtained in the fourth step by the weight of each box obtained in the third step and summing the values over all the boxes, and the weight of each box over all the boxes. The weighted average motor loss was calculated by dividing the sum by the value (fifth step).
The average motor loss calculation result when the center point of the box area is selected as the representative operating point in the fourth step is shown in FIG. 10, and the average motor when the center of gravity of the operating point included in each box is selected as the representative operating point. The loss calculation results are shown in FIG.

  10 and 11, the average motor loss decreases in the order of motor b <motor a <motor c, and it was confirmed that the results of FIG. 6 can be reproduced. Further, when the results of FIGS. 6, 10, and 11 are combined and shown in FIG. 12, the operation points included in each box as the representative operation points than when the center point of the box area is selected as the representative operation point. It was also confirmed that the results shown in FIG. 6 can be reproduced more accurately when the center of gravity is selected.

10 Motor core material selection device (computer)
An n-th operating point among a plurality of operating points passing through Bm m-th box region among a plurality of box regions to be divided Tmax Surrounded by a motor maximum torque curve in an operating point space defined by torque T and rotation speed N region

Claims (3)

In the operating point space defined by the torque and the number of revolutions, the motor core material specified by the torque and the number of revolutions is used as the motor core material used under the driving conditions that pass through multiple points over time. A method of selecting,
A first step of dividing a region surrounded by the motor maximum torque curve in the operating point space into a plurality of box regions;
A plurality of box regions determined in the first step for each motor operation point corresponding to the operation duration time while obtaining an operation duration time for each motor operation point obtained by following the motor operation point according to the elapsed operation time. A second step of determining which box area to enter,
A third step of taking the sum of the operation durations of the motor operating points entering each of the box areas and determining the value of the sum as a weight ratio of the box area to the total motor operating time;
A fourth step of determining a representative operating point for each box area and obtaining motor characteristics at the representative operating point for all box areas;
A fifth step of obtaining a weighted average motor characteristic in the total motor operation time by dividing the sum of the products of the weight ratio for each box area and the motor characteristics by the sum of the weight ratios for each box area;
And a sixth step of selecting a material to be adopted by obtaining a weighted average motor characteristic based on the first to fifth steps for each material to be selected and comparing them with each other. The method of selecting the material for the motor core.   According to the number of motor operating points in the operating point space, the area to be divided into box areas is divided so that the area where the number of motor operating points is large is smaller than the area where the number of motor operating points is small. The method for selecting a motor core material according to claim 1.   3. The motor core material according to claim 1, wherein a center of gravity weighted by an operation duration time of each motor operation point is adopted as the representative operation point determined for each box region in the fourth step. Selection method.

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