Motor selection device and motor selection method

Abstract

A motor selection device (10) comprising: a speed calculation unit (16) configured to calculate a motor selection speed from a speed waveform of a motor configured to drive a specific driven object, taking into account iron losses generated in a target motor serving as an object to be selected, the speed waveform being obtained when the driven object is made to perform a prescribed operation, a storage unit (22) configured to store a motor characteristic associated with a speed of the target motor serving as the object to be selected, and a determination unit (24) configured to determine whether or not the prescribed operation is possible by the target motor, wherein the motor characteristic is used at the motor selection speed.

Description

Background of the inventionField of the invention

[0001] The present invention relates to a motor selection device and a motor selection method for selecting a suitable motor. Description of the state of the art

[0002] As described in JP 2018 - 153 045 A, in a conventional motor selection device, motor selection is performed by determining whether or not a root mean square (rms) torque during operation is less than a continuous torque (rated torque) of the motor.

[0003] DE 10 2018 105 315 A1 discloses a motor selection device that executes a motor selection method. The motor selection device comprises a computer, an input device, and a display device. The computer has a memory unit that stores a motor selection program. Furthermore, the display device is connected to a motor selection means. Summary of the invention

[0004] When rotating at high speed, iron losses are generated in the motor, and heat generation increases. Accordingly, if the motor is selected by determining that the effective torque value is less than or equal to the rated torque of the motor at a time when the rotation speed is low, the selection is made without considering the heat due to iron losses. When the motor selected in this way rotates at high speed, there has been a problem that the motor overheats, which is disadvantageous. In other words, the motor has been selected without considering the heat generation due to iron losses.

[0005] Therefore, it is an object of the present invention to propose a motor selection device and a motor selection method with which it is possible to select a motor taking into account the generation of iron losses.

[0006] A first aspect of the present invention is characterized by a motor selection device comprising a speed calculation unit configured to calculate a motor selection speed from a speed waveform (speed waveform) of a motor configured to drive a specified driven object, taking into account the iron losses generated in a target motor serving as the object to be selected, the speed waveform being obtained when the driven object is made to perform a prescribed operation, a storage unit configured to store a motor characteristic corresponding to a speed of the target motor serving as the object to be selected, and a determination unit configured to determine whether or not the prescribed operation is possible by the target motor,using the motor characteristic associated with the motor selection speed.,

[0007] A second aspect of the present invention is characterized by a motor selection method for a motor selection device having a storage unit, wherein the storage unit is configured to store a motor characteristic associated with a speed of a target motor serving as an object to be selected, the motor selection method comprising a speed calculation step for calculating a motor selection speed from a speed waveform (speed vibration characteristic) of a motor configured to drive a predetermined driven object, taking into account the iron losses generated in the target motor serving as the object to be selected, the speed waveform being obtained when the driven object is made to perform a predetermined operation, and a determination step for determiningwhether the prescribed operation is possible by the target motor or not, using the motor characteristic associated with the motor selection speed.

[0008] With the present invention, it is possible to select a motor taking into account the generation of iron losses.

[0009] The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which preferred embodiments of the present invention are shown by way of example. Short description of the drawings Fig. 1 is a schematic diagram showing the configuration of a motor selection device according to an embodiment, Fig. 2 is a diagram showing an operation pattern of a driven object determined according to the operating conditions, Fig. 3 is a diagram showing a speed waveform of the driven object obtained by simulation, Fig. 4 is a diagram showing a torque waveform of a motor obtained by simulation, Fig. 5 is a diagram showing a time change (speed waveform) of the speed of a motor, Fig. 6 is a diagram showing a rated torque associated with a speed of a target motor, Fig. 7 is a flowchart illustrating a motor selection method according to an embodiment, and Fig. 8 is a schematic diagram showing the configuration of a motor selecting device according to a fourth modification. Description of the preferred embodiments

[0010] Preferred embodiments of a motor selecting apparatus and a motor selecting method according to the present invention will be presented and described in detail below with reference to the accompanying drawings. [Embodiments]

[0011] Fig. 1 is a schematic diagram of the configuration of a motor selection device 10 according to an embodiment of the present invention. The motor selection device 10 is a device that assists in the selection of a motor by indicating to a user whether a motor serving as an object to be selected satisfies a capability required of the motor driving a driven object when making the driven object perform a prescribed operation.

[0012] The motor selection device 10 includes a condition acquisition unit 12, a simulation unit 14, a speed calculation unit 16, an average torque / thrust calculation unit 18, a storage unit 22, a determination unit 24, and an output unit 26. The motor selection device 10 includes a processor, such as a central processing unit (CPU) or the like, and a memory, and serves as the motor selection device 10 of the present embodiment by executing a program stored in the memory. A display unit 28 is installed externally of the motor selection device 10. The display unit 28 displays the output results of the simulation unit 14 and the output unit 26. Note that the display unit 28 may also be provided as a part of the motor selection device 10.

[0013] The condition acquisition unit 12 acquires a mechanical condition of a driven object (not shown) driven by a motor (not shown) and a working condition indicating a prescribed working pattern, the conditions being input by the user. The driven object includes all objects driven by the motor. A ball screw mechanism is provided at a distal end of the motor. By the rotational movement of the motor, a table on which a nut is installed is moved linearly. Accordingly, the driven elements include a ball screw, the nut, the table, and a workpiece or the like mounted on the table. In the following description, the rotational speed of the motor may also be simply referred to as speed.

[0014] The mechanical condition acquired by the condition acquisition unit 12 is a physical quantity related to the driven object and includes parameters such as the length and diameter of the ball screw, the masses of the table and workpiece, and the friction coefficient. The working condition acquired by the condition acquisition unit 12 includes parameters that define a prescribed work pattern, such as a movement distance and a movement speed of the table and workpiece. Since the prescribed operation by the predetermined driven object is determined by the mechanical condition and the working condition acquired by the condition acquisition unit 12, the condition acquisition unit 12 outputs the acquired mechanical condition and working condition to the simulation unit 14.

[0015] The simulation unit 14 obtains, through simulation, a speed waveform and a torque waveform of the motor that drives the prescribed driven object when the driven object is made to perform the prescribed operation based on the mechanical condition and the working condition input from the condition obtaining unit 12.

[0016] Fig. Figure 2 is a diagram showing a working pattern of the driven object, which is determined according to the working conditions. Fig. 2, the horizontal axis indicates time, and the vertical axis indicates the position of the table (or workpiece). Fig. 2 shows a working pattern in which the table (or workpiece) moves one meter in a specified direction during a specified period of time and then stops.

[0017] Fig. Figure 3 is a diagram showing a speed waveform of the driven object obtained by simulation. In Fig. 3, the horizontal axis indicates time, and the vertical axis indicates the speed of the table (or workpiece). If Fig. 3 Therefore, when the units of the vertical axis are changed, the speed waveform of the motor is obtained. Fig. Figure 4 is a graph showing a torque waveform of the motor obtained by simulation. In Fig. 4, the horizontal axis indicates time, and the vertical axis indicates the torque of the motor. As shown in the Fig. 3 and Fig. 4, the simulation unit 14 determines a rotational speed waveform and a torque waveform of the motor in the case where the driven object is the one shown in Fig. 2, and displays on the display unit 28 the waveforms together with Fig. 2 that can be shown to the user.

[0018] The speed calculation unit 16 calculates a motor selection speed from the motor speed waveform obtained by simulation in the simulation unit 14, taking into account the iron losses generated in the target motor serving as the object to be selected. The speed calculation unit 16 outputs the calculated motor selection speed to the determination unit 24.

[0019] The following describes a method in which the speed calculation unit 16 calculates the motor selection speed based on the speed waveform, taking into account the iron loss generated in the target motor. First, the iron loss generated in the motor is calculated using the equation Iron Loss = A × Speed ​​+ B × (Speed) 2expressed using a coefficient A and coefficient B, which are determined depending on the target engine.

[0020] Fig. Figure 5 is a graph showing a time change (speed waveform) of the motor speed. The vertical axis indicates the (rotational) speed of the motor, and the horizontal axis indicates time. Fig. 5 shows that the speed is maintained at N1 during the period t1, the speed is maintained at N2 during the period t2, ..., and the speed is maintained at Nn during the period tn. Furthermore, this temporal change of the speed is repeated in the form of a cycle over the period T. In this case, T = t1 + t2 + ... + tn. In such a case, the total amount of heat X generated by iron losses in the target motor with the coefficient A and the coefficient B is expressed by the following equation (1). X=A×(N1×t1+N2×t2+…+Nn×tn)+B×(N12×t1+N22×t2+…+Nn2×tn)

[0021] In addition, the amount Y of heat generated per unit time is expressed by the following equation (2). Y=A×(N1×t1+N2×t2+…+Nn×tn) / T+B×(N12×t1+N22×t2+…+Nn2×tn)

[0022] In this case, (N1 × t1 + N2 × t2 + ... + Nn × tn) / T is an average speed Nmean determined by performing a calculation of the arithmetic mean of the speed waveform, and (N1 2 × t1 + N2 2 × t2 + ... + Nn 2 × tn) / T is the square of a root mean square (rms) of the velocity Nrms, which is determined by performing a root mean square calculation from the velocity waveform. Accordingly, the amount Y of heat generated per unit time can be expressed by the following equation (3). Y=A×Nmean+B×Nrms2

[0023] Assuming that at constant speed of the motor, a speed producing an amount of heat generated per unit time equal to Y from equation (3) is given by a motor selection speed Ns, the following relationship is obtained in this case. A×Nmean+B×Nrms2=A×Ns+B×Ns2

[0024] If equation (4) is solved for Ns and its positive solution is selected, the value Ns is obtained by the following equation (5). Ns=(1 / 2)(−A / B+√(A2 / B2+4((A / B)×Nmean+Nrms2)))

[0025] In the above manner, the speed calculation unit 16 determines the motor selection speed Ns. By using equation (5), the motor selection speed can be determined with high accuracy while taking the iron losses into account.

[0026] The average torque / thrust calculation unit 18 calculates the effective value of the torque from the torque waveform obtained by simulation by the simulation unit 14 and outputs the effective value of the torque to the determination unit 24.

[0027] The storage unit 22 stores the motor characteristic associated with the speed of the target motor serving as the object to be selected. In this case, the motor characteristic stored in the storage unit 22 is a rated torque. Accordingly, the storage unit 22 stores a relationship between a rated torque associated with a speed and each of the multiple motors. Fig. Figure 6 is a graph showing a nominal torque associated with the speed of the target motor. In Fig. 6, the vertical axis indicates torque, and the horizontal axis indicates speed. Since the target motor can operate continuously at any speed with a torque less than or equal to the rated torque, the zone of such torque is shown as a continuous operating zone.

[0028] The determination unit 24 determines whether the prescribed operation of the driven object is possible by the target motor using the motor characteristic associated with the motor selection speed. Specifically, the determination unit 24 compares the effective torque value obtained by the average torque / thrust calculation unit 18 with the rated torque associated with the motor selection speed of the target motor, which is obtained by accessing the storage unit 22. Then, the determination unit 24 determines whether the effective torque value is less than or equal to the aforementioned rated torque. If the effective torque value is less than or equal to the rated torque, the target motor can be used to make the predetermined driven object perform the prescribed operation.In this case, the target motor that is the subject of such a comparison is a motor that serves as an object to be selected from the plurality of motors for which the storage unit 22 stores relationships between the rated torques associated with the speeds and the motors.

[0029] As in Fig. For example, as shown in Figure 6, when the effective value of the torque calculated by the average torque / thrust calculation unit 18 is A0, a point a at which the effective value of the torque becomes A0 at the motor selection speed calculated by the speed calculation unit 16 is included in the continuous operation zone. In this case, the determination unit 24 determines that the effective value of the torque is less than or equal to the rated torque and that the prescribed operation of the driven object is possible by the target motor. In addition, when the effective value of the torque calculated by the average torque / thrust calculation unit 18 is B0, a point b at which the effective value of the torque becomes B0 at the motor selection speed calculated by the speed calculation unit 16 is not included in the continuous operation zone.Since the effective torque value is not less than or equal to the rated torque in this case, the determination unit 24 determines that the prescribed operation of the driven object by the target motor is not possible. The determination unit 24 outputs the above-mentioned determination result to the output unit 26.

[0030] The output unit 26 outputs a notification signal to provide notification of the determination result of the determination unit 24. By displaying the content of the notification signal output by the output unit 26, the display unit 28 notifies the user whether the target motor can be used or not.

[0031] Fig. 7 is a flowchart showing a motor selection method according to the embodiment. Before the flowchart according to Fig. 7 begins, the condition acquisition unit 12 outputs the acquired mechanical condition and working condition to the simulation unit 14.

[0032] First, the simulation unit 14 simulates the speed waveform and the torque waveform of the motor that drives the predetermined driven object when making the driven object perform the prescribed operation based on the mechanical condition and the working condition input from the condition acquiring unit 12 (step S1).

[0033] Next, the speed calculation unit 16 calculates the motor selection speed from the speed waveform obtained in step S1 and outputs the motor selection speed to the determination unit 24 (step S2).

[0034] The average torque / thrust calculation unit 18 calculates the effective value of the torque from the torque waveform obtained in step S1 and outputs the effective value of the torque to the determination unit 24 (step S3).

[0035] The determination unit 24 compares the effective torque value calculated by the average torque / thrust calculation unit 18 with the rated torque of the target motor associated with the motor selection speed determined by the speed calculation unit 16, and determines whether the effective torque value is less than or equal to the rated torque (step S4). The determination unit 24 outputs the determination result to the output unit 26 based on the determination made in step S4 and whether the prescribed operation of the driven object is possible by the target motor.

[0036] The output unit 26 outputs the notification signal to provide the notification of the determination result to the determination unit 24 (step S5) and causes the content of the notification signal to be displayed on the display unit 28.

[0037] As described above, the motor selection device 10 of the present embodiment compares the effective torque value with the rated torque of the motor, which serves as the object to be selected for the motor selection speed. By determining whether the effective torque value is equal to or less than the rated torque, it is possible to select the motor taking into account the iron loss generated in the motor, since a determination can be made as to whether or not the prescribed operation of the driven object is possible by the target motor.

[0038] This makes it possible to select the engine in a better way than with the state of the art. [Modifications]

[0039] The embodiment described above can be modified in the following manner. (Modification 1)

[0040] In the above-described embodiment, the speed calculation unit 16 calculates the motor selection speed Ns using equation (5), taking into account the iron loss generated in the target motor. Since equation (5) is somewhat complicated, in a first modification (Modification 1), the effective value of the speed Nrms, which is determined by the speed calculation unit 16 performing an effective value calculation from the speed waveform, is regarded as an approximate value of equation (5). Such a value is used as the motor selection speed. Even when considering the iron loss generated in the target motor, this feature makes it possible to determine the motor selection speed with a lower calculation cost. (Modification 2)

[0041] In the above-described embodiment, the speed calculation unit 16 calculates the motor selection speed Ns using equation (5), taking into account the iron loss generated in the target motor. Since equation (5) is somewhat complicated, in a second modification (Modification 2), the average speed Nmean, which is determined by the speed calculation unit 16 performing the arithmetic mean calculation based on the speed waveform, is regarded as an approximate value of equation (5), and this value is used as the motor selection speed. Even when the iron loss generated in the target motor is taken into account, this feature makes it possible to determine the motor selection speed with a lower calculation cost. (Modification 3)

[0042] In the above-described embodiment, the motor is assumed to be a rotary motor. However, in the third embodiment (Modification 3), the motor is assumed to be a linear motor that does not perform rotary motion. In Modification 3, the simulation unit 14 obtains, through simulation, the speed waveform and a thrust waveform of the motor that drives the predetermined driven object when the driven object is made to perform the prescribed operation based on the mechanical condition and the working condition input from the condition acquisition unit 12.

[0043] Furthermore, the average torque / thrust calculation unit 18 calculates the effective value of the thrust force from the thrust waveform of the motor obtained through simulation by the simulation unit 14 and outputs the effective value of the thrust force to the determination unit 24. Furthermore, the motor characteristic associated with the speed of the target motor, which is stored in the storage unit 22, is a rated thrust force. The determination unit 24 compares the effective value of the thrust force obtained by the average torque / thrust calculation unit 18 with the rated thrust force of the target motor associated with the motor selection speed, which is obtained by accessing the storage unit 22.

[0044] Then, the determination unit 24 determines whether the effective value of the thrust force is less than or equal to the aforementioned rated thrust force. If the effective value of the thrust force is less than or equal to the rated thrust force, a determination is made that the target motor can be used to make the predetermined driven object perform the prescribed operation. By taking iron losses into account, it becomes possible to select a linear motor more accurately than in the prior art. (Modification 4)

[0045] Fig. Fig. 8 is a schematic diagram of the configuration of a motor selection device 10 according to a fourth modification (Modification 4). Fig. 8, the average torque / thrust calculation unit 18 is selected according to Fig.1 is replaced by an average current calculation unit 30. In Modification 4, the simulation unit 14 obtains, through simulation, the speed waveform and a current waveform of the motor that drives the predetermined driven object when the driven object is made to perform the prescribed operation based on the mechanical condition and the working condition input from the condition acquisition unit 12.

[0046] Furthermore, the average current calculation unit 30 calculates the effective current value from the motor current waveform obtained through simulation by the simulation unit 14 and outputs the effective current value to the determination unit 24. Furthermore, the motor characteristic associated with the speed of the target motor, which is stored in the storage unit 22, is a rated current. The determination unit 24 compares the effective current value obtained by the average current calculation unit 30 with the rated current associated with the motor selection speed of the target motor, which is obtained by accessing the storage unit 22.

[0047] Then, the determination unit 24 determines whether the effective current value is less than or equal to the rated current described above. If the effective current value is less than or equal to the rated current, a determination can be made that the target motor can be used to make the predetermined driven object perform the prescribed operation. This feature also makes it possible to select the motor more accurately than the prior art, taking iron loss into account, even when the current waveform of the motor is used. (Modification 5)

[0048] In the above-described embodiment and modifications 3 and 4, the speed waveform, torque waveform, thrust waveform, and current waveform of the motor are obtained through simulation performed by the simulation unit 14. However, actual measured values ​​obtained in advance may also be used. Based on these measured values, the speed calculation unit 16, the average torque / thrust calculation unit 18, or the average current calculation unit 30 can calculate the motor selection speed, the effective value of the torque, the effective value of the thrust, or the effective value of the current. Accordingly, the simulation can be omitted. (Modification 6)

[0049] The embodiment described above and its modifications can be combined in a suitable manner as long as no technical contradictions arise. [Inventions derivable from the embodiments]

[0050] The following is a description of the inventions which can be derived from the embodiments described above. (First invention)

[0051] The motor selection device (10) is equipped with the speed calculation unit (16) which calculates the motor selection speed from the speed waveform of the motor that drives the predetermined driven object, taking into account iron losses generated in the target motor serving as the object to be selected, the speed waveform being determined when the driven object is caused to perform a prescribed operation, the storage unit (22) which stores the motor characteristic associated with the speed of the target motor serving as the object to be selected, and the determination unit (24) which determines whether or not the prescribed operation is possible by the target motor, using the motor characteristic associated with the motor selection speed.

[0052] This feature allows the motor to be selected taking into account the iron losses generated in the motor, and the motor can be selected in a better manner than the prior art.

[0053] The motor selection device (10) may further be equipped with the average torque / thrust force calculation unit (18) that calculates the effective value of the torque or the effective value of the thrust from the torque waveform or the thrust waveform of the motor that drives the driven object, respectively, and / or the average current calculation unit (30) that calculates the effective value of the current from the current waveform of the motor, the torque waveform, the thrust waveform and the current waveform being obtained when the driven object is made to perform the prescribed operation, and the output unit (26) that outputs the notification signal to provide notification of the determination result of the determination unit (24).The motor characteristic may be the rated torque, the rated thrust force or the rated current of the target motor, and the determination unit (24) may determine whether or not the effective value of the torque, the effective value of the thrust force or the effective value of the current is less than or equal to the rated torque, the rated thrust force or the rated current of the target motor according to the motor selection speed.

[0054] The speed calculation unit (16) can calculate the motor selection speed using the relational expression Ns = (1 / 2) (-A / B + √ (A 2 / B 2 + 4 ((A / B) × Nmean + Nrms 2 ))) where the iron loss is expressed by Iron loss = A × speed + B × (speed) 2Using coefficient A and coefficient B, which are determined depending on the target motor, where Nmean denotes the average speed determined from the speed waveform, Nrms denotes the effective speed determined from the speed waveform, and Ns denotes the motor selection speed. With these features, the motor can be selected with high accuracy while taking into account the iron losses generated in the motor.

[0055] The speed calculation unit 16 can calculate the motor selection speed by performing the calculation of the effective value.

[0056] This feature makes it possible to determine the motor selection speed with lower calculation costs, taking into account the iron losses generated in the target motor.

[0057] The speed calculation unit (16) can calculate the motor selection speed by performing the arithmetic mean calculation. This feature makes it possible to determine the motor selection speed with lower calculation costs, taking into account the iron losses generated in the target motor. (Second invention)

[0058] A motor selection method is proposed for the motor selection device (10) having the storage unit (22), wherein the storage unit (22) stores the motor characteristic associated with the speed of the target motor serving as the object to be selected, the motor selection method comprising the speed calculation step of calculating the motor selection speed from the speed waveform of the motor configured to drive the predetermined driven object, taking into account the iron loss generated in the target motor serving as the object to be selected, the speed waveform being obtained when the driven object is caused to perform a prescribed operation, and the determination step of determining whether or not the prescribed operation is possible by the target motor, using the motor characteristic associated with the motor selection speed.This feature allows the motor to be selected taking into account the iron losses generated in the motor, and the motor can be selected in a better manner than the prior art.

[0059] The motor selection method further includes the average torque / thrust calculation step of calculating the effective value of the torque or the effective value of the thrust from the torque waveform or the thrust waveform of the motor driving the driven object, respectively, and / or the average current calculation step of calculating the effective value of the current from the current waveform of the motor, wherein the torque waveform, the thrust waveform, and the current waveform are obtained when the driven object performs the prescribed operation, and the output step of outputting the notification signal to provide notification of the determination result of the determination unit. The motor characteristic may be the rated torque, the rated thrust, or the rated current of the target motor.In the determination step, it can be determined whether the effective value of the torque, the effective value of the thrust force or the effective value of the current is less than or equal to the rated torque, the rated thrust force or the rated current of the target motor at the motor selection speed or not.

[0060] In the speed calculation step, the motor selection speed can be calculated using the relational expression Ns = (1 / 2) (-A / B + √ (A 2 / B 2 + 4 ((A / B) × Nmean + Nrms 2 ))) where the iron losses are expressed by Iron loss = A × speed + B × (speed) 2, where coefficient A and coefficient B are used, which are determined depending on the target motor, and where Nmean denotes the average speed determined from the speed waveform, Nrms denotes the effective speed value determined from the speed waveform, and Ns denotes the motor selection speed. These features allow the motor to be selected with high accuracy while taking into account the iron losses generated in the motor.

[0061] In the speed calculation step, the motor selection speed can be calculated by calculating the effective value. This feature makes it possible to determine the motor selection speed with lower calculation costs, taking into account the iron losses generated in the target motor.

[0062] In the speed calculation step, the motor selection speed can be determined by performing an arithmetic mean calculation. This feature makes it possible to determine the motor selection speed with lower calculation costs, taking into account the iron losses generated in the target motor.

Claims

[1] A motor selection device (10) comprising: a speed calculation unit (16) configured to calculate a motor selection speed from a speed waveform of a motor configured to drive a specific driven object, taking into account iron losses generated in a target motor serving as an object to be selected, the speed waveform being obtained when the driven object is made to perform a prescribed operation, a storage unit (22) designed to store a motor characteristic associated with a speed of the target motor serving as the object to be selected, and a determination unit (24) configured to determine whether or not the prescribed operation is possible by the target motor, wherein the motor characteristic is used at the motor selection speed. [2] The motor selection device according to claim 1, further comprising an average torque / thrust calculation unit (18) configured to calculate the effective value of the torque or the effective value of the thrust from a torque waveform or a thrust waveform of the motor configured to drive the driven object, and / or an average current calculation unit (30) configured to calculate the effective value of the current from a current waveform of the motor, wherein the torque waveform, the thrust waveform and the current waveform are obtained when the driven object is made to perform the prescribed operation, and an output unit (26) configured to output a notification signal to provide notification of the determination result of the determination unit, where the motor characteristic is a rated torque, a rated thrust or a rated current of the target motor, and wherein the determination unit is configured to determine whether or not the effective value of the torque, the effective value of the thrust force, or the effective value of the current is less than or equal to the rated torque, the rated thrust force, or the rated current of the target motor at the motor selection speed. [3] The motor selection device according to claim 1 or 2, wherein the speed calculation unit is configured to calculate the motor selection speed using the following equation Ns=(1 / 2)(−A / B+√(A2 / B2+4((A / B)×Nmean+Nrms2))) where the iron loss is expressed by Iron loss = A × speed + B × (speed) 2 using a coefficient A and a coefficient B determined depending on the target motor, and where Nmean denotes an average speed determined from the speed waveform, Nrms denotes the effective value of the speed determined from the speed waveform, and Ns denotes the motor selection speed. [4] The motor selection device according to any one of claims 1 to 3, wherein the speed calculation unit is configured to calculate the motor selection speed by calculating the effective value. [5] The motor selection device according to any one of claims 1 to 3, wherein the speed calculation unit is configured to calculate the motor selection speed by calculating the arithmetic mean. [6] A motor selection method for a motor selection device (10) having a storage unit (22), wherein the storage unit is designed to store a motor characteristic at a speed of a target motor serving as an object to be selected, where the engine selection process includes: a speed calculation step for calculating a motor selection speed from a speed waveform of a motor configured to drive a specific driven object, taking into account iron losses generated in the target motor serving as the object to be selected, the speed waveform being obtained when the driven object is made to perform a prescribed operation, and a determination step of determining whether or not the prescribed operation is possible by the target motor using the motor characteristic at the motor selection speed. [7] The engine selection method according to claim 6, further comprising: an average torque / thrust calculation step for calculating the effective value of the torque or the effective value of the thrust from a torque waveform or a thrust waveform of the motor configured to drive the driven object, and / or an average current calculation step for calculating the effective value of the current from a current waveform of the motor, wherein the torque waveform, the thrust waveform, and the current waveform are obtained when the driven object is made to perform the prescribed operation, and an output step for outputting a notification signal to provide notification of a determination result of the determination unit, where the motor characteristic is a rated torque, a rated thrust or a rated current of the target motor, and wherein in the determining step, it is determined whether or not the effective value of the torque, the effective value of the thrust force, or the effective value of the current is less than or equal to the rated torque, the rated thrust force, or the rated current of the target motor at the motor selection speed. [8] The motor selection method according to claim 6 or 7, wherein in the speed calculation step, the motor selection speed is calculated using the following equation Ns=(1 / 2)(−A / B+√(A2 / B2+4((A / B)×Nmean+Nrms2))) where the iron loss is expressed by Iron loss = A × speed + B × (speed) 2using a coefficient A and a coefficient B determined depending on the target motor, and where Nmean represents an average speed determined from the speed waveform, Nrms represents an effective speed determined from the speed waveform, and Ns represents the motor selection speed. [9] The motor selection method according to any one of claims 6 to 8, wherein in the speed calculation step, the motor selection speed is calculated by calculating the effective value. [10] The motor selection method according to any one of claims 6 to 8, wherein in the speed calculation step, the motor selection speed is calculated by calculating the arithmetic mean.

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