Engine selection device and engine selection procedure

Abstract

An engine selection device (10) comprising: a velocity calculation unit (16) configured to calculate an average velocity from a velocity waveform of a motor configured to drive a specific driven object, wherein the velocity waveform is obtained when the driven object is made to perform a prescribed operation, a current calculation unit (18) configured to calculate the RMS value of the current from a current waveform of the motor configured to drive the driven object, wherein the current waveform is obtained when the driven object is allowed to perform the prescribed operation, a storage unit (22) designed to store a motor characteristic for a speed of a target motor serving as the object to be selected, and a determination unit (24) designed to determine whether the prescribed operation is possible by the target motor or not, using the motor characteristics at average speed and the RMS value of the current.

Description

Background of the invention; Field of the invention

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

[0002] As described in the Japanese patent publication JP 2018 - 153 045 A, in a conventional motor selection device, motor selection is carried out by determining whether a root mean square (RMS) value of the torque during the execution of a work operation is less than the rated torque of the motor or not. Summary of the invention

[0003] The technology described in Japanese patent publication JP 2018-153045A uses a velocity waveform to obtain the root mean square (RMS) torque, but it does not account for the reactive current component (reactive current component) in the current flowing through the motor. In contrast, the rated torque is measured by actually driving the motor, and this includes the influence of the reactive current component. Therefore, the reactive current component is not adequately addressed when comparing the two torque values, resulting in a low degree of accuracy.

[0004] Therefore, the present invention has the objective of proposing a motor selection device and a motor selection method with which it is possible to select a motor taking into account a reactive current component flowing through the motor.

[0005] A first aspect of the present invention is characterized by a motor selection device comprising a speed calculation unit configured to calculate an average speed from a speed waveform of a motor configured to drive a specific, predetermined object, wherein the speed waveform is obtained when the driven object is caused to perform a prescribed operation; a current calculation unit configured to calculate the root mean square (RMS) value of the current from a current waveform of the motor configured to drive the driven object, wherein the current waveform is obtained when the driven object is caused to perform the predetermined operation; and a storage unit configured to store a motor characteristic.which corresponds to the speed of a target motor, which serves as an object to be selected, and a determination unit designed to determine whether the predetermined operation is possible by the target motor or not, using the motor characteristic corresponding to the average speed and the RMS value of the current.

[0006] A second aspect of the present invention is characterized by a motor selection method for a motor selection device with 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, wherein the motor selection method comprises a speed calculation step for calculating an average speed from a speed waveform of a motor configured to drive a specific driven object, wherein the speed waveform is obtained when the driven object is caused to perform a predetermined operation, and a current calculation step for calculating an RMS value of the current from a current waveform of the motor configured to drive the driven object, wherein the current waveform is obtained.when the driven object is caused to perform the prescribed operation, and a determination step to ascertain whether the prescribed operation is possible by the target motor or not, using the motor characteristic associated with the average speed and the RMS value of the current.

[0007] With the present invention it is possible to select a motor taking into account a reactive current component flowing through the motor.

[0008] The above and further tasks, features and advantages of the present invention will become even clearer from the following description in conjunction with the accompanying drawings, in which preferred embodiments of the present invention are illustrated by way of example. Brief description of the drawings Fig. Figure 1 is a schematic representation of the configuration of an engine selection device according to one embodiment, Fig. 2 is a diagram showing a working pattern of a driven object, which is determined according to working conditions, Fig. Figure 3 is a diagram showing a velocity waveform of the driven object, obtained through a simulation. Fig. Figure 4 is a diagram showing a torque waveform of a motor obtained through simulation. Fig. Figure 5 is a diagram showing a current waveform of a motor obtained through simulation. Fig. Figure 6 is a diagram showing a rated current corresponding to a speed of a target motor. Fig. 7 is a flowchart representing an engine selection procedure according to one embodiment, Fig. Figure 8 is a schematic representation of the configuration of an engine selection device according to a first modification, Fig. Figure 9 is a diagram showing a rated torque corresponding to the speed of a target motor in the first modification. Fig. Figure 10 is a flowchart representing an engine selection procedure according to the first modification, and Fig. Figure 11 is a schematic representation showing the configuration of an engine selection device according to a second modification. Description of preferred embodiments

[0009] Preferred embodiments of an engine selection device and an engine selection method according to the present invention are presented and described in detail below with reference to the accompanying drawings. [Versions]

[0010] Fig. Figure 1 is a schematic representation 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 fulfills the required properties for a motor that drives a driven object when the driven object performs a prescribed operation.

[0011] The motor selection device 10 comprises a condition acquisition unit 12, a simulation unit 14, a velocity calculation unit 16, a current calculation unit 18, a storage unit 22, a determination unit 24, and an output unit 26. The motor selection device 10 includes a processor, for example, a central processing unit (CPU) or the like, and 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 to the motor selection device 10, and the display unit 28 shows the output results of the simulation unit 14 and the output unit 26. Note that the display unit 28 can also be provided as part of the motor selection device 10.

[0012] The condition procurement unit 12 procures a mechanical condition of a driven object (not shown) powered by a motor (not shown), and a working condition specifying a prescribed operating pattern, with the conditions being entered by the user. The driven object consists of all driven elements powered by the motor. A ball screw mechanism is provided at a distal end of the motor, and a rotary motion of the motor sets a table, on which a nut is installed, into linear motion. Accordingly, the driven elements include a ball screw, the nut, the table, and a workpiece or the like mounted on the table. Furthermore, in the following description, the rotational speed of the motor may also be referred to simply as speed.

[0013] The mechanical condition procured by condition procurement unit 12 is a physical quantity relating 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 a coefficient of friction. The working condition procured by condition procurement unit 12 includes parameters that define a prescribed work pattern, such as the distance traveled and the speed of movement of the table and workpiece. Since the prescribed operation by a predetermined driven object is determined by the mechanical condition and the working condition procured by condition procurement unit 12, condition procurement unit 12 outputs the procured mechanical condition and working condition to simulation unit 14.

[0014] The simulation unit 14 determines by simulation a velocity waveform (velocity waveform), a torque waveform (torque waveform) and a current waveform (current waveform) of the motor that drives the predetermined driven object when the driven object performs the prescribed operation based on the mechanical condition and the working condition specified by the condition procurement unit 12.

[0015] Fig. Figure 2 is a diagram showing a working pattern of the driven object, determined according to the operating conditions. Fig. 2. The horizontal axis indicates time, and the vertical axis indicates the position of the table (or workpiece). In Fig. Figure 2 shows a work pattern in which, during a predetermined period of time, the table (or workpiece) moves one meter in a specified direction and then stops.

[0016] Fig. Figure 3 is a diagram showing a velocity waveform of the driven object, obtained through simulation. Fig. 3. The horizontal axis indicates time, and the vertical axis indicates the speed of the table (or workpiece). If in Fig. 3. By changing the units of the vertical axis, the speed waveform of the motor will be obtained. Fig. Figure 4 is a diagram showing a torque waveform of the motor, obtained through simulation. Fig. 4. The horizontal axis indicates time, and the vertical axis indicates the torque of the motor. Fig. Figure 5 is a diagram showing a current waveform of the motor, obtained through simulation. Fig. 5. The horizontal axis indicates time, and the vertical axis indicates the motor's current. As in the Fig. 3, Fig. 4 and Fig. As shown in section 5, the simulation unit 14 determines a rotational speed waveform, a torque waveform, and a current waveform of the motor when the driven object is shown in Fig. 2 allows the operation shown to be performed, and displays the waveform along with Fig. 2, which can be shown to the user, on display unit 28.

[0017] The speed calculation unit 16 calculates an average speed from the motor's speed waveform, which is determined by simulation from the simulation unit 14. The speed calculation unit 16 can calculate the average speed by using the arithmetic mean of speed values ​​taken at several points in time selected from the speed waveform, or it can determine the average speed by an RMS calculation. The average speed can be a value obtained by performing a specific averaging calculation based on the speed waveform.

[0018] The current calculation unit 18 calculates an RMS value of the current from the current waveform determined by simulation from the simulation unit 14 and outputs the RMS value of the current to the determination unit 24. In this case, the calculated RMS value of the current is a value that includes an effective current component and a reactive current component.

[0019] The storage unit 22 stores the motor characteristic associated with the speed of the target motor used as the object to be selected. In this case, the motor characteristic stored in the storage unit 22 is a rated current. Accordingly, the storage unit 22 stores a relationship between a rated current associated with a speed and each of the multiple motors. The rated currents stored in the storage unit 22 include the RMS current component and the reactive current component. Fig. Figure 6 is a diagram showing a rated current associated with a speed of a target motor. Fig. Figure 6 shows the current on the vertical axis, the speed on the horizontal axis, and the rated current is indicated by the solid line. Since the target motor can be operated continuously with a current that is less than or equal to the rated current at each of the respective speeds, the zone of such a current is shown as a continuous operating zone. Furthermore, an aspect is shown where a reactive current component I d (dashed line) is generated at a velocity of Nd or higher. Accordingly, the effective current component I decreases. q (dashed line) that is included in the nominal current.

[0020] The determination unit 24 uses the motor characteristic associated with the average speed and the RMS value of the current to determine whether the prescribed operation of the driven object is possible with the target motor. Specifically, the determination unit 24 compares the RMS value of the current, determined by the current calculation unit 18, with the rated current, which is associated with the average speed of the target motor and determined by accessing the storage unit 22. The determination unit 24 then determines whether the RMS value of the current is less than or equal to the aforementioned rated current. If the RMS value of the current is less than or equal to the rated current, it is determined that the target motor can be used to make the predetermined driven objects perform the prescribed operation.If the RMS value of the current is greater than the rated current, it is determined that the target motor cannot be used to drive the specified object and perform the specified operation. In this case, the target motor being compared is a motor that serves as a selectable object from among several motors, for which the storage unit stores 22 relationships between the rated currents assigned to the speeds and the motors.

[0021] If, as in Fig. As shown in Figure 6, for example, if the RMS value of the current calculated by the current calculation unit 18 is equal to A0, then a point A at which the RMS value of the current at the average speed calculated by the speed calculation unit 16 is equal to A0 is included in the continuous operating zone. Since in this case the RMS value of the current A0 is less than or equal to a rated current value B0 associated with the average speed calculated by the speed calculation unit 16, the determination unit 24 determines that the prescribed operation of the driven object by the target motor is possible. Conversely, if the RMS value of the current A0 is greater than the rated current value B0 associated with the average speed, the determination unit 24 determines that the prescribed operation of the driven object by the target motor is impossible.The determination unit 24 outputs the above-mentioned determination result to the output unit 26.

[0022] Output unit 26 emits a notification signal to provide information about the determination result of the determination unit 24. By displaying the content of the notification signal emitted by output unit 26, display unit 28 informs the user whether the target engine can be used or not.

[0023] Fig. 7 is a flowchart that represents an engine selection procedure according to the embodiment. Before the flowchart according to Fig. When 7 is started, the condition procurement unit 12 outputs the procured mechanical condition and operating condition to the simulation unit 14.

[0024] First, the simulation unit 14 simulates the velocity waveform, torque waveform, and current waveform of the motor driving the predetermined driven object when the driven object is caused to perform the prescribed operation, based on the mechanical condition and the operating condition entered by the condition procurement unit 12 (step S1).

[0025] Next, the velocity calculation unit 16 calculates the average velocity from the velocity waveform obtained in step S1 and outputs the average velocity to the determination unit 24 (step S2).

[0026] The current calculation unit 18 calculates the RMS value of the current from the current waveform obtained in step S1 and outputs the RMS value of the current to the determination unit 24 (step S3).

[0027] The determination unit 24 compares the RMS value of the current calculated by the current calculation unit 18 with the rated current of the target motor, which is assigned to the average speed determined by the speed calculation unit 16, and determines whether the RMS value of the current is less than or equal to the rated current (step S4). Based on the determination made in step S4 as to whether the prescribed operation of the driven object is possible with the target motor, the determination unit 24 outputs the result to the output unit 26.

[0028] The output unit 26 outputs the notification signal to provide a notification about the determination result of the determination unit 24 (step S5) and causes the content of the notification signal to be displayed on the display unit 28.

[0029] As described above, the motor selection device 10 of the present embodiment compares the RMS value of the current with the rated current of the motor, which serves as the object to be selected, at average speed. By determining whether the RMS value of the current is less than or equal to the rated current, it is also possible to determine whether the prescribed operation of the driven object is possible with the target motor. Since values ​​containing the RMS current component and the reactive current component are compared, it is accordingly possible to select the motor taking into account the reactive current component flowing through the motor. This makes it possible to perform the motor selection more effectively than with conventional technology. [Modifications]

[0030] The embodiment described above can be modified in the manner described below. (Modification 1)

[0031] Fig. Figure 8 is a schematic representation of the configuration of an engine selection device 10 according to a first modification (Modification 1). In the engine selection device 10, which is described in Fig. As shown in section 8, the engine selection device 10 is shown in accordance with Fig. In modification 1, a continuous torque calculation unit 30 is added. In the embodiment described above, the motor selection device 10 compares the RMS value of the current, which includes the RMS current component and the reactive current component, with the rated current, which includes the RMS current component and the reactive current component. This determines whether the prescribed operation is possible for the target motor. Accordingly, the motor can be selected, taking the reactive current component into account. In modification 1, the motor selection device 10 converts the RMS value of the current, which includes the reactive current component, into a continuous torque. By comparing the continuous torque with a rated torque, it determines whether the prescribed operation is possible for the target motor.

[0032] The continuous torque calculation unit 30 calculates the continuous torque, taking into account the reactive current component, from the RMS value of the current input by the current calculation unit 18 and outputs the calculated continuous torque to the determination unit 24. In addition, in modification 1, the storage unit 22 stores the rated torque as the motor characteristic. Fig. Figure 9 is a diagram showing a rated torque associated with the speed of a target motor in modification 1. Fig. Figure 9 shows the continuous torque on the vertical axis, the speed on the horizontal axis, and the rated torque with the solid line. Since the target motor can be operated continuously with a constant torque (continuous torque) that is less than or equal to the rated torque at all speeds, the zone of such rated torque is shown as a continuous operating zone. Additionally, an aspect is shown where the reactive current component flows at a speed Nd or higher, and the rated torque is further reduced by the reactive current component (dashed line) at a speed of Nd or higher.

[0033] The following describes a specific procedure by which the continuous torque calculation unit 30 calculates the continuous torque from the RMS value of the current, taking the reactive current component into account. An RMS value of the current I rmsis defined by the following equation (1). In equation (1), the term I describes a a function whose variable is time and which specifies the current waveform obtained by simulation from the simulation unit 14. Irms=∫Ia2dtt

[0034] In this case, a continuous torque T can be applied. rms by the following equation (2) from the RMS value of the current I rms to be calculated. In equation (2) the term K t a torque constant. Trms=Kt⋅Irms

[0035] In this case, the continuous torque calculation unit 30 can be derived from the rotational speed, which is obtained from the velocity waveform obtained through simulation, and the continuous torque T. rms a reactive power component I d at Nmeanat the average speed determined by the speed calculation unit 16. Additionally, the continuous torque calculation unit 30 calculates a continuous torque T. rms ' by removing the reactive power component I d at Nmean at the average speed from the RMS value of the current I rms , as in the following equation (3). Trms'=Kt(Irms2−Id at Nmean2)

[0036] In Fig. 9 is a point C, a point at which the value of the continuous torque at the average speed is equal to T. rms will be, and a point D is a point at which the value of the continuous torque at average speed is equal to T rms ' becomes.

[0037] Furthermore, the unit of measurement 24 compares the continuous torque T. rms', which is obtained from the continuous torque calculation unit 30, with the rated torque assigned to the average speed of the target motor, which is obtained by accessing the storage unit 22. In addition, the determination unit 24 determines whether the continuous torque T rms 'is equal to or less than the rated torque or not. If the continuous torque T rms If the continuous torque is less than or equal to the rated torque, it is determined that the target motor can be used to cause the predetermined driven object to perform the prescribed operation. If the continuous torque T rms If the torque exceeds the rated torque, a determination is made that the target motor cannot be used to make the predetermined driven object perform the prescribed operation. Fig. 9. Initially, it is considered unsuitable to measure the continuous torque T. rms(Point C) to compare with the rated torque, because the rated torque is already reduced by a value that corresponds to the reactive power component I d at Nmean at average speed. However, in modification 1, the continuous torque T rms ' (Point D) is calculated by performing a conversion in which the value of I d at Nmean of the effective value of the current I rms is removed, and the continuous torque T rms ' is compared with the rated torque, allowing for an accurate evaluation and a result from which the target motor can be selected.

[0038] Fig. 10 is a flowchart showing an engine selection procedure according to modification 1. Before the flowchart according to Fig. When step 10 begins, the condition procurement unit 12 outputs the procured mechanical condition and operating condition to the simulation unit 14. Steps S11, S12, S13, and S16 are the same as steps S1, S2, S3, and S5 in Fig. 7, so that the description of these steps is omitted. The following is a description of the steps that differ from those in Fig. 7 distinguish.

[0039] In step S14, the continuous torque calculation unit 30 calculates the continuous torque T. rms ', by reducing the reactive power component I d N mean , which are derived from the RMS value of the current I in the manner described above rms , which was entered by the current calculation unit 18, is removed, and gives the calculated continuous torque T. rms ' to the determination unit 24.

[0040] In step S15, the determining unit 24 compares the continuous torque T. rms', which was calculated by the continuous torque calculation unit 30, with the rated torque of the target motor, which is assigned to the average speed determined by the speed calculation unit 16, and determines whether the continuous torque T rms 'is less than or equal to the rated torque or not. The determination unit 24 outputs the determination result to the output unit 26 based on the determination made in step S15, which indicates whether the prescribed operation of the driven object is possible by the target motor or not.

[0041] In the manner described above, in modification 1 the motor selection device 10 compares the continuous torque T rms ', which is achieved by removing the reactive power component I d at Nmean of the effective value of the current I rmsThe value obtained is the rated torque, which excludes the reactive current component. Since values ​​that exclude the reactive current component are compared, it is possible to select the motor based on the reactive current flowing through it. This allows for a more suitable motor selection than with conventional methods. (Modification 2)

[0042] In the embodiment described above, the motor was assumed to be a rotary motor. In the second modification (Modification 2), however, the motor is assumed to be a linear motor that does not perform a rotary movement. Fig. Figure 11 schematically shows the configuration of a motor selection device 10 according to modification 2. In the Fig. The motor selection device 10 shown in 11 is the one in Fig. The continuous torque calculation unit 30 shown in Figure 8 is replaced by a continuous thrust calculation unit 40. In modification 2, the motor selection device 10 converts the RMS value of the current, which includes the reactive current component, into a continuous thrust force. By comparing the continuous thrust force with a rated thrust force, it determines whether the prescribed operation is possible with the target motor.

[0043] The continuous thrust calculation unit 40 calculates the continuous thrust, taking into account the reactive current component, from the RMS value of the current input by the current calculation unit 18 and outputs the calculated continuous thrust to the determination unit 24. Additionally, in modification 2, the storage unit 22 stores the rated thrust as the motor characteristic.

[0044] A specific procedure, in which the continuous thrust calculation unit 40 calculates the continuous thrust from the RMS value of the current taking into account the reactive current component, is described below.

[0045] First, a continuous thrust force F can be rms by the following equation (4) from the RMS value of the current I rms calculated according to equation (1), which is output by the current calculation unit 18. In equation (4) the term K f a shear force constant. Frms=Kf⋅Irms

[0046] In this case, the continuous thrust calculation unit 40 can be derived from the speed of the motor, which is determined from the velocity waveform obtained through simulation, and the continuous thrust force F. rms the reactive power component I d at NmeanThe average speed is determined by the speed calculation unit 16. Additionally, the continuous thrust calculation unit 40 calculates a continuous thrust force F. rms ' by removing the reactive power component I d at Nmean at the average speed of the effective value of the current I rms , as in the following equation (5). Frms'=Kf(Irms2−Id at Nmean2)

[0047] Furthermore, the unit of measurement 24 compares the fatigue force F rms ', which was obtained from the continuous thrust calculation unit 40 with the rated thrust at the average speed of the target engine, which was obtained by accessing the storage unit 22. In addition, the determination unit 24 determines whether the continuous thrust F rms 'is less than or equal to the nominal thrust force or not. If the fatigue thrust F rmsIf the rated thrust is less than or equal to the rated thrust, it is determined that the target motor can be used to make the specified driven object perform the prescribed operation. If the continuous thrust F rms If the thrust is greater than the rated thrust, a determination is made that the target motor cannot be used to make the predetermined driven object perform the prescribed operation. Since, in modification 2, the continuous thrust F rms ' is calculated by performing a conversion in which the value of I d at Nmean from the RMS value of the current I rms is removed, and the continuous thrust force F rms By comparing it with the nominal thrust, an accurate evaluation can be carried out and a result obtained with which the target motor can be selected.

[0048] The engine selection procedure according to modification 2 can be described by step S14 in the flow diagram according to Fig. 10 is replaced by a step in which the fatigue force calculation unit 40 is the fatigue force F rms ' calculated, and by replacing step S15 with a step in which the determining unit 24 determines whether the fatigue shear force F rms ' is equal to or less than the rated thrust of the target engine at average speed.

[0049] In the manner described above, in modification 2 the motor selection device 10 compares the continuous thrust force F rms ', which is achieved by removing the reactive power component I d at Nmean from the RMS value of the current I rmsThe value obtained is the rated thrust, where the thrust component is not included due to the reactive current component. Since values ​​are compared that do not include the thrust component due to the reactive current component, it is possible to select the motor taking into account the reactive current component flowing through the motor. This allows for a more suitable motor selection than with conventional techniques. (Modification 3)

[0050] In the embodiment and modification 1 described above, the speed waveform, torque waveform, and current waveform of the motor are obtained by simulation performed by the simulation unit 14. However, actual measured values ​​determined beforehand can also be used. Based on such measured values, the speed calculation unit 16, the current calculation unit 18, and the continuous torque calculation unit 30 can calculate the average speed, the RMS value of the current, and the continuous torque, respectively. Accordingly, the simulation can be omitted. (Modification 4)

[0051] The embodiment described above and its modifications can be combined in a suitable manner, provided that this does not result in any technical contradictions. [Inventions resulting from the embodiments]

[0052] The following is a description of the inventions that can be derived from the embodiments described above. (First invention)

[0053] The motor selection device (10) comprises the speed calculation unit (16), which calculates an average speed from a speed waveform of a motor driving a specific driven object, wherein the speed waveform is obtained when the driven object is made to perform a prescribed operation; the current calculation unit (18), which calculates the RMS value of the current from a current waveform of the motor driving the driven object, wherein the current waveform is obtained when the driven object is made to perform the prescribed operation; the storage unit (22), which stores the motor characteristic associated with the speed of a target motor serving as the selection object; and the determination unit (24), which determines whether the prescribed operation is possible for the target motor or not.using the motor characteristic associated with the average speed and the RMS value of the current.

[0054] These features make it possible to select the motor while taking into account the reactive power component flowing through it. This allows for a more suitable motor selection than with conventional techniques.

[0055] The motor characteristic can be a rated current. The determining unit (24) can determine whether the prescribed operation is possible with the target motor by determining whether the RMS value of the current is less than or equal to the rated current of the target motor at average speed. Since these characteristics compare values ​​that include the RMS current component and the reactive current component, it is possible to select the motor taking into account the rated current component flowing through the motor.

[0056] The motor characteristic can be a rated current or a rated thrust. The motor selection device (10) can also include a continuous torque calculation unit (30) or a continuous thrust calculation unit (40), which calculates the continuous torque or continuous thrust from the RMS value of the current, taking into account the reactive current component. The determination unit (24) can determine whether the predetermined operation is possible with the target motor by determining whether the continuous torque or continuous thrust is less than or equal to the rated current or rated thrust of the target motor at the average speed. Since these characteristics compare values ​​that do not include the torque component or the thrust component due to the reactive current component, it is possible to select the motor taking into account the reactive current component flowing through the motor.

[0057] The motor selection device (10) can also include the output unit (26), which outputs the notification signal to provide a notification about the determination result of the determination unit (24). This feature makes it possible to notify the user whether the target motor can be used or not. (Second invention)

[0058] In the motor selection procedure for the motor selection device (10), which includes the storage unit (22), the storage unit (22) stores the motor characteristic associated with the speed of the target motor serving as the object to be selected, and includes the speed calculation step for calculating the average speed from a speed waveform of the motor designed to drive a specific driven object, wherein the speed waveform is obtained when the driven object is allowed to perform a prescribed operation, the current calculation step for calculating the RMS value of the current from a current waveform of the motor designed to drive the driven object, wherein the current waveform is obtained when the driven object is allowed to perform the prescribed operation, and the determination step for determining,whether the prescribed operation is possible by the target motor or not, using the motor characteristic associated with the average speed and the RMS value of the current.

[0059] These features make it possible to select the motor taking into account the reactive power component flowing through it. This allows for a more suitable motor selection than with conventional techniques.

[0060] The motor characteristic can be a rated current. In the selection step, it can be determined whether the predetermined operation is possible with the target motor by determining whether the RMS value of the current is less than or equal to the rated current of the target motor at average speed. Since these characteristics compare values ​​that include the RMS current component and the reactive current component, it is possible to select the motor taking into account the reactive current component flowing through the motor.

[0061] The motor characteristic can be a rated torque or a rated thrust. The motor selection procedure can also include a continuous torque calculation step or a continuous thrust calculation step to calculate the continuous torque or thrust from the RMS value of the current, taking the reactive power component into account. In the determination step, it can be determined whether the prescribed operation is possible with the target motor by determining whether the continuous torque or thrust is less than or equal to the rated torque or thrust of the target motor at the average speed. Since these characteristics compare values ​​that do not include the torque or thrust component due to the reactive power component, it is possible to select the motor taking into account the reactive power component flowing through the motor.

[0062] The motor selection process can also include an output step for issuing a notification signal to provide a notification of the determination result of the selection step. This feature makes it possible to notify the user whether the target motor can be used or not.

Claims

[1] An engine selection device (10) comprising: a velocity calculation unit (16) configured to calculate an average velocity from a velocity waveform of a motor configured to drive a specific driven object, wherein the velocity waveform is obtained when the driven object is made to perform a prescribed operation, a current calculation unit (18) configured to calculate the RMS value of the current from a current waveform of the motor configured to drive the driven object, wherein the current waveform is obtained when the driven object is allowed to perform the prescribed operation, a storage unit (22) designed to store a motor characteristic for a speed of a target motor serving as the object to be selected, and a determination unit (24) designed to determine whether the prescribed operation is possible by the target motor or not, using the motor characteristics at average speed and the RMS value of the current. [2] The motor selection device according to claim 1, wherein the motor characteristic is a rated current, and wherein the selection unit is configured to determine whether the prescribed operation is possible by the target motor or not by determining whether the RMS value of the current is less than or equal to the rated current of the target motor at the average speed or not. [3] The motor selection device according to claim 1, wherein the motor characteristic is a rated torque or a rated thrust, wherein the motor selection device also comprises a continuous torque calculation unit (30) or a continuous thrust calculation unit (40) configured to calculate a continuous torque or a continuous thrust from the RMS value of the current taking into account a reactive current component, and wherein the determining unit is designed to determine whether the prescribed operation is possible by the target motor or not by determining whether the continuous torque or continuous thrust at the average speed is less than or equal to the rated torque or rated thrust of the target motor or not. [4] The motor selection device (10) according to one of claims 1 to 3, further comprising an output unit (26) configured to output a notification signal in order to provide notification of a determination result of the determination unit. [5] A motor selection method for a motor selection device (10) with a storage unit (22), wherein the storage unit is configured to store a motor characteristic for a speed of a target motor serving as an object to be selected, the engine selection process includes: a velocity calculation step for calculating an average velocity from a velocity waveform of a motor designed to drive a specified driven object, wherein the velocity waveform is obtained by having the driven object perform a prescribed operation, a current calculation step for calculating the RMS value of a current from a current waveform of the motor designed to drive the driven object, wherein the current waveform is obtained when the driven object is allowed to perform the prescribed operation, and a determination step to determine whether the prescribed operation is possible by the target motor or not, using the motor characteristics at average speed and the RMS value of the current. [6] The motor selection method according to claim 5, wherein the motor characteristic is a rated current, and wherein in the determination step a determination is made as to whether the prescribed operation is possible by the target motor or not by determining whether the RMS value of the current at the average speed is less than or equal to the rated current of the target motor or not. [7] The motor selection method according to claim 5, wherein the motor characteristic is a rated torque or a rated thrust, wherein the motor selection procedure also includes a continuous torque calculation step or a continuous thrust calculation step for calculating a continuous torque or a continuous thrust from the RMS value of the current taking into account a reactive current component, and wherein in the determination step a determination is made as to whether the prescribed operation is possible by the target motor or not, by determining whether the continuous torque or continuous thrust at the average speed is less than or equal to the rated torque or rated thrust of the target motor or not. [8] The motor selection method according to any one of claims 5 to 7, further comprising an output step for outputting a notification signal to provide notification of a determination result of the determination step.

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