Control device and sensorless vector control correction device

Abstract

To provide a control device and a sensorless vector control correction device that can perform sensorless vector control with high accuracy in the drive control of a bridle roll.SOLUTION: The embodiment includes speed feedback estimation value correction calculation means. The speed feedback estimation value correction calculation means calculates a corrected speed feedback estimation value for sensorless speed control on the basis of the speed feedback estimation value calculated by using a drive device output current and a speed feedback actual measurement value detected by a speed sensor and outputs it to the drive device that performs sensorless speed control.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a control device and a sensorless vector control correction device for a bridle roll drive control system. [Background technology]

[0002] A drive device is sometimes used to operate an induction motor at variable speed. To control the speed or torque of an induction motor with high precision, a sensor-equipped vector control is often used, in which a speed sensor is attached to the rotating shaft of the induction motor and the speed feedback is used as an input signal for the drive device.

[0003] On the other hand, in the case of induction motors that do not require high-precision control, sensorless vector control is used in which the actual speed is estimated from the output voltage and output current of the drive device without attaching a speed sensor to the rotating shaft of the induction motor, and vector control is performed using the speed feedback estimated value.

[0004] Conventionally, a method has been proposed for switching to a control method that does not require a speed sensor when a speed sensor fails in an induction motor driven by sensor-equipped vector control. For example, Patent Document 1 discloses a technology for performing sensorless vector control by switching the speed feedback of the induction motor from an actual value measured by the speed sensor to an estimated value obtained from the output voltage and output current of the drive device when the speed sensor fails. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 1-167156 Summary of the Invention [Problem to be solved by the invention]

[0006] In this conventional technology, if an induction motor equipped with a speed sensor is driven by vector control and the speed sensor fails, the control switches to sensorless vector control, and the speed feedback switches from an actual measured value to an estimated value. However, this method cannot be applied in cases where a speed sensor cannot be installed in the first place.

[0007] The estimated value of speed feedback in sensorless vector control is not as accurate as the actual measured value. The estimated value of speed feedback may not necessarily match the actual measured value of speed feedback detected by the speed sensor. During extremely low speed operation such as zero speed or at the zero crossing where forward and reverse rotation switches, the speed control accuracy may decrease, causing deviations in vector control and making the control system unstable.

[0008] Bridle rolls are installed in steel processing lines where unbroken strip is continuously transported. Bridle rolls consist of two or more rolls, and restrain the strip by the friction of the roll surfaces and the angle at which the strip is wrapped around the rolls. As a result, the speed of the bridle rolls can be made to nearly match the transport speed of the strip, so the bridle roll can act as the speed master for the entire line, and high speed control accuracy is required.

[0009] In renewal engineering work to replace part or all of old equipment with new equipment, it may be difficult to install speed sensors depending on the layout of the bridle rolls and the induction motors that drive them. Furthermore, if the number of speed sensors required can be reduced, renewal costs can also be reduced. In such cases, there is a strong demand for the application of sensorless vector control without sacrificing the speed control accuracy of the bridle rolls.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a control device and a sensorless vector control correction device that are capable of performing sensorless vector control with high accuracy in drive control of a bridle roll. [Means for solving the problem]

[0011] An embodiment of the present invention is a control device for a bridle roll drive control system including a plurality of bridle rolls, a plurality of induction motors each driving the plurality of bridle rolls, at least one induction motor among the plurality of induction motors that is subjected to sensor-based speed control, the remaining induction motors among the plurality of induction motors that are subjected to sensorless speed control, at least one drive device controlling the at least one induction motor, and the remaining drive devices controlling the remaining induction motors. The control device includes speed feedback estimate value correction calculation means that calculates a correction value for the remaining speed feedback estimate based on at least one speed feedback estimate calculated for the at least one induction motor using at least one drive current detected by the at least one drive device, remaining speed feedback estimates calculated for the remaining induction motors using the remaining drive currents detected by the remaining drive devices, and at least one actual speed feedback measurement value for the at least one induction motor, and calculates and outputs the corrected remaining speed feedback estimate. The speed feedback estimated value correction calculation means calculates a difference between the at least one speed feedback actual measurement value and the at least one speed feedback estimated value, and calculates the corrected remaining speed feedback estimated value based on a statistical calculation of the difference. [Effects of the Invention]

[0012] According to the embodiment, a control device and a sensorless vector control correction device are provided that can perform sensorless vector control with high accuracy in drive control of a bridle roll. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic block diagram illustrating a bridle roll drive control system to which a control device according to a first embodiment is applied. FIG. [Figure 2] 2 is a schematic block diagram illustrating a census vector control correction device that is a part of the control device according to the first embodiment. FIG. [Figure 3] FIG. 10 is a schematic block diagram illustrating a sensorless vector control correction device according to a second embodiment. [Figure 4] FIG. 10 is a schematic block diagram illustrating a bridle roll drive control system for explaining a method of using a sensorless vector control correction device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0015] (First embodiment) First, the configuration of the bridle roll drive control system will be described. FIG. 1 is a schematic block diagram illustrating a bridle roll drive control system to which a sensorless vector control correction device according to a first embodiment is applied. As shown in Fig. 1, the bridle roll drive control system includes bridle rolls 2a to 2d, induction motors 4a to 4d, speed sensors 6a and 6b, drive devices 10a to 10d, and a control device 100. The bridle rolls 2a to 2d, induction motors 4a to 4d, and speed sensors 6a and 6b are mechanical devices and equipment, and are provided, for example, in a rolling line. The drive devices 10a to 10d and the control device 100 are electrical control devices and equipment, and are provided, for example, in an electrical room of a rolling plant.

[0016] The strip 1 is wound around the bridle rolls 2a to 2d so as not to slip off the rolls. The bridle rolls 2a to 2d are driven by induction motors 4a to 4d. The speeds of the induction motors 4a to 4d are controlled by drive devices 10a to 10d, respectively, and the strip 1 is transported between the bridle rolls at both ends.

[0017] As shown by the arrows in Figure 1, the strip 1 is conveyed in the order of the bridle rolls 2a to 2d. That is, the bridle rolls 2a and 2b are provided at the entrance side of the conveyance path of the strip 1, and the bridle rolls 2c and 2d are provided at the exit side of the conveyance path of the strip 1. For example, the speeds of the bridle rolls 2a to 2d are set to be approximately the same. For example, by maintaining the speeds of the bridle rolls 2a to 2d constant, the tension of the strip 1 between the bridle rolls is controlled to a desired value.

[0018] The induction motors 4a and 4b are provided with speed sensors 6a and 6b, respectively. The speed sensor 6a outputs the measured speed feedback value of the induction motor 4a to the drive device 10a, and the speed sensor 6b outputs the measured speed feedback value of the induction motor 4b to the drive device 10b. The speed sensors 6a and 6b measure the speeds of the induction motors 4a and 4b, respectively, and output the measured speed feedback values ​​to the control device 100.

[0019] The control device 100 outputs a preset speed reference for each of the drive devices 10a and 10b to the drive devices 10a and 10b.

[0020] The induction motors 4c and 4d are not provided with speed sensors. That is, the induction motors 4c and 4d are subjected to sensorless speed control by the drive devices 10c and 10d. On the other hand, the induction motors 4a and 4b, which are provided with speed sensors 6a and 6b, are subjected to sensor-equipped speed control by the drive devices 10a and 10b.

[0021] Current sensors are provided at the outputs of the drive devices 10a to 10d. The current sensors detect the current values ​​output by the drive devices 10a to 10d, calculate speed feedback estimates using the detected current values, and output the speed feedback estimates to the control device 100.

[0022] A sensorless vector control correction device (speed feedback estimate value correction calculation means) 20 of the control device 100 calculates correction values ​​of speed feedback estimates (remaining speed feedback estimates) for the induction motors 4c and 4d based on the speed feedback actual measurement values ​​(at least one speed feedback actual measurement value) of the induction motors 4a and 4b and the speed feedback estimate values ​​(at least one speed feedback estimate value) of the induction motors 4a and 4b, and calculates and outputs corrected speed feedback estimates (corrected remaining speed feedback estimates). Drive devices 10c and 10d generate speed command values ​​based on the corrected speed feedback estimate values ​​and a preset speed reference, and output output voltages and output currents according to the speed command values ​​to the induction motors 4c and 4d, respectively.

[0023] An example of the configuration of the drive devices 10a to 10d will be described below. The drive devices 10a to 10d each include drive units 11a to 11d, torque controllers 12a to 12d, speed controllers 14a to 14d, and sensorless controllers 16a to 16d.

[0024] The speed controllers 14a and 14b calculate current command values ​​based on the actual speed feedback value and the speed reference output from the speed reference output unit 30, and output them to the torque controllers 12a and 12b, respectively. The torque controllers 12a and 12b generate speed command values ​​for the induction motors 4a and 4b based on the current command values ​​and the current values ​​output by the drive devices 10a and 10b, and output them to the drive devices 10a and 10b, respectively. The speed command values ​​output to the drive devices 10a and 10b are calculated by the speed controllers 14a and 14b and the torque controllers 12a and 12b.

[0025] The speed controllers 14c and 14d calculate current command values ​​based on the corrected speed feedback estimate value output from the sensorless vector control corrector 20 and the speed reference output from the speed reference output unit 30, and output the current command values ​​to the torque controllers 12c and 12d, respectively. The torque controllers 12c and 12d generate speed command values ​​for the induction motors 4c and 4d based on the current command values ​​and the current values ​​output from the drive units 10c and 10d, and output the speed command values ​​to the drive units 11c and 11d, respectively.

[0026] Torque controllers 12a to 12d output speed command values ​​to drive units 11a to 11d. Drive units 11a to 11d output voltages and currents for driving induction motors 4a to 4d based on the speed command values.

[0027] Sensorless controllers 16a to 16d detect current values ​​output by drive devices 10a to 10d, and use the detected current values ​​to calculate speed feedback estimates for induction motors 4a to 4d, and output the speed feedback estimates to control device 100.

[0028] The control device 100 includes a sensorless vector control correction device 20. The control device 100 also includes a speed reference output unit 30. The configuration of the sensorless vector control correction device 20 will be described. FIG. 2 is a schematic block diagram illustrating the sensorless vector control correction device according to the first embodiment. In the following explanation, the actual speed feedback measurements of induction motors 4a and 4b are denoted as "SP_F1" and "SP_F2," respectively. Furthermore, the speed feedback estimates calculated based on the output currents of drive devices 10a to 10d are denoted as "SP_F1_SL" to "SP_F4_SL," respectively. Furthermore, the corrected speed feedback estimates calculated for speed control of induction motors 4c and 4d are denoted as "SP_F3_E" and "SP_F4_E," respectively.

[0029] 2, the sensorless vector control correction device 20 has a correction calculation unit 22. The correction calculation unit 22 calculates and outputs corrected speed feedback estimated values ​​SP_F3_E and SP_F4_E based on the speed feedback actual measured values ​​SP_F1 and SP_F2 and the speed feedback estimated values ​​SP_F1_SL to SP_F4_SL.

[0030] The correction calculation unit 22 receives a difference ΔSP_F1 between the speed feedback actual measurement value SP_F1 and the speed feedback estimate value SP_F1_SL. The correction calculation unit 22 also receives a difference ΔSP_F2 between the speed feedback actual measurement value SP_F2 and the speed feedback estimate value SP_F2_SL. The correction calculation unit 22 calculates the arithmetic mean of the difference ΔSP_F1 and the difference ΔSP_F2, and outputs the arithmetic mean as a correction value ΔSP_AVE for the speed feedback estimate value.

[0031] The sensorless vector control corrector 20 adds a correction value ΔSP_AVE to the speed feedback estimate SP_F3_SL for speed control of the induction motor 4c to calculate and output a corrected speed feedback estimate SP_F3_E. The sensorless vector control corrector 20 adds a correction value ΔSP_AVE to the speed feedback estimate SP_F4_SL for speed control of the induction motor 4d to calculate and output a corrected speed feedback estimate SP_F4_E.

[0032] The bridle rolls 2a to 2d are mechanically coupled by the strip 1, and when the tension of the strip is controlled, the speeds of the bridle rolls 2a to 2d are approximately the same. In other words, the differences ΔSP_F1 and ΔSP_F2 represent the deviation between the actual speed feedback value and the estimated speed feedback value for the induction motors 4a and 4b that are subjected to sensor-based speed control. Although the speeds of the induction motors 4c and 4d that are subjected to sensorless speed control are not actually measured, adding the correction value ΔSP_AVE to the respective speed feedback estimated values ​​SP_F3_SL and SP_F4_SL results in estimated values ​​that are closer to the actual speed feedback values.

[0033] In this way, the sensorless vector control correction device 20 corrects the speed feedback estimate value of the induction motor subjected to sensorless speed control based on the difference between the speed feedback actual measurement value and the speed feedback estimate value of the induction motor subjected to sensor-equipped speed control. As a result, the corrected speed feedback estimate value becomes close to the speed feedback actual measurement value of the induction motor, thereby realizing highly accurate sensorless speed control.

[0034] In the above-described specific example, of the four induction motors 4a to 4d, the induction motors 4a and 4b on the entry side of the conveying path are controlled by sensor-equipped speed control, but the position of the induction motors to be subjected to sensor-equipped speed control is not limited to this. For example, the induction motors 4c and 4d on the exit side of the conveying path may be subjected to sensor-equipped speed control, or other combinations may be used.

[0035] In the above-described specific example, two of the four induction motors 4a to 4d are subjected to sensor-assisted speed control, but the number of induction motors subjected to sensor-assisted speed control is not limited to this. For example, three induction motors at any position may be subjected to sensor-assisted speed control, and the remaining induction motors may be subjected to sensorless speed control. In this embodiment, it is sufficient that at least one induction motor is subjected to sensor-assisted speed control.

[0036] Specifically, the correction calculation unit 22 of the sensorless vector control correction device 20 can calculate a correction value ΔSP_AVE for the speed feedback estimated value using the following equation (1).

[0037] ΔSP_AVE=(1 / n)Σ[ΔSP_Fi] (1) Here, ΔSP_Fi = SP_Fi - SP_Fi_SL "n" is the number of induction motors with sensors to be speed-controlled. i = 1 to n, and "i" is an identification number that identifies the induction motor with sensors to be speed-controlled. In the above specific example, i = 1 represents induction motor 4a, and i = 2 represents induction motor 4b.

[0038] From equation (1), the sensorless vector control correction device 20 can calculate a correction value for sensorless speed control and output a corrected speed feedback estimated value.

[0039] In the above example, the correction value of the speed feedback estimated value is the arithmetic mean of ΔSP_Fi, but other appropriate statistical calculations may be used depending on the number and configuration of the bridle rolls. For example, the median of ΔSP_Fi may be used, or if ΔSP_Fi is outside a predetermined range, outliers may be excluded from the calculation of the average value.

[0040] The effects of the control device 100 according to this embodiment will be described. The control device 100 according to this embodiment includes a sensorless vector control correction device 20. The sensorless vector control correction device 20 has a correction calculation unit 22, which calculates the arithmetic mean of the difference between the actual speed feedback value of at least one induction motor subjected to sensor-equipped speed control and the estimated speed feedback value of that induction motor, and outputs the calculated value as a correction value for the speed feedback estimate. The speed feedback estimate value used to calculate this correction value is calculated based on the current value driving the sensor-equipped speed-controlled induction motor. Therefore, the speed feedback estimate value corrected by the correction value is close to the actual speed of the induction motor subjected to sensorless speed control. This enables accurate sensorless speed control even when the induction motor subjected to sensorless speed control is operating at extremely low speeds or at zero crossings.

[0041] (Second embodiment) Renewal engineering work is sometimes carried out in plants where bridle roll drive control systems are installed. Renewal engineering work refers to the technical work of replacing part or all of the existing electrical equipment, mechanical equipment, etc. with new equipment. When carrying out such renewal engineering work on a bridle roll drive control system, it is sometimes not possible to install speed sensors on all of the induction motors that drive the bridle rolls.

[0042] FIG. 3 is a schematic block diagram illustrating a sensorless vector control correction device according to the second embodiment. FIG. 4 is a schematic block diagram illustrating a bridle roll drive control system for explaining a method of using a sensorless vector control correction device according to the second embodiment.

[0043] In the renewal engineering work for the bridle roll drive control system, a sensorless vector control correction device 220 shown in FIG. 3 is prepared. As shown in Fig. 3, the sensorless vector control correction device 220 is configured to be able to output corrected speed feedback estimates in a number corresponding to the number of induction motors to be speed-controlled. In the specific example of Fig. 3, it is configured to be able to output four speed feedback estimates SP_F1_E to SP_F4_E so that it can be applied regardless of which of the four induction motors is under sensor-based speed control and which is under sensorless speed control.

[0044] Specifically, the sensorless vector control corrector 220 is configured to calculate differences ΔSP_F1 to ΔSP_F4 between the actual speed feedback values ​​SP_F1 to SP_F4 and the speed feedback estimates SP_F1_SL to SP_F4_SL of the four induction motors, respectively. More specifically, the sensorless vector control corrector 220 has a correction calculator 22, which can calculate a correction value ΔSP_AVE for each of the speed feedback estimates SP_F1_SL to SP_F4_SL using the above-mentioned equation (1). The sensorless vector control corrector 220 can add the correction value ΔSP_AVE to the speed feedback estimates SP_F1_SL to SP_F4_SL to calculate and output corrected speed feedback estimates SP_F1_E to SP_F4_E.

[0045] The sensorless vector control correction device 220 according to this embodiment preferably includes a selection unit 224. During update engineering, the selection unit 224 selects a system for which a corrected speed feedback estimated value needs to be output, depending on whether a speed sensor is installed in the speed control system to be updated. For example, the sensorless vector control correction device 220 is configured with program modules, and the system selection by the selection unit 224 is a module that selects the corresponding program module. For example, the system to be selected is selected and set via the selection unit 224 on a computer terminal functioning as an engineering tool. The system selection by the selection unit 224 may be automatically determined by hardware based on the presence or absence of each input signal. For example, if the speed feedback actual measurement values ​​SP_F2 and SP_F3 are not input, the selection unit 224 automatically determines that the induction motors 4a and 4d are under sensor-based speed control and the induction motors 4b and 4c are under sensorless speed control, and switches between them using a switch or the like.

[0046] Figure 4 shows an example of updating an existing bridle roll speed control system. As shown in Figure 4, in this example, it is difficult to install speed sensors on the first induction motor 4a and the fourth induction motor 4d, so sensorless speed control is applied to the induction motors 4a and 4d. Note that the speed sensors 6a and 6d that cannot be installed on the induction motors 4a and 4d during the update are marked with an "x."

[0047] The sensorless vector control correction device 220 according to this embodiment is applied to an updated bridle roll speed control system that uses induction motors 4b and 4c that perform sensor-based speed control and induction motors 4a and 4d that perform sensorless speed control.

[0048] In the updated bridle roll speed control system, the sensorless controllers 16a to 16d shown in Fig. 1 are added to the drive devices 10a to 10d, respectively. Similar to the case of Fig. 1, the sensorless controllers 16a to 16d are configured to receive the currents output by the drive devices 10a to 10d, calculate speed feedback estimated values, and output the values ​​to the control device 220.

[0049] Speed ​​feedback estimated values ​​SP_F1_SL to SP_F4_SL output from the added sensorless controllers 16a to 16d are input to the sensorless vector control correction device 20. In addition, the speed feedback actual measurement value SP_F2 of the induction motor 4b and the speed feedback actual measurement value SP_F3 of the induction motor 4c are input to the sensorless vector control correction device 20.

[0050] The sensorless vector control corrector 220 calculates the difference ΔSP_F2 between the speed feedback actual measurement value SP_F2 and the speed feedback estimate value SP_F2_SL for the induction motor 4b. The sensorless vector control corrector 220 also calculates the difference ΔSP_F3 between the speed feedback actual measurement value SP_F3 and the speed feedback estimate value SP_F3_SL for the induction motor 4c.

[0051] The sensorless vector control corrector 220 calculates the correction value ΔSP_AVE of the speed feedback estimated value using the equation (1) described in relation to FIGS.

[0052] The sensorless vector control corrector 220 calculates corrected speed feedback estimated values ​​SP_F1_E and SP_F4_E so as to perform sensorless speed control on the induction motors 4a and 4d, and outputs them to the speed controllers 14a and 14d.

[0053] In this way, when updating an existing bridle roll speed control system, even in a situation where it is not possible to install a speed sensor, it is possible to perform highly accurate sensorless speed control.

[0054] The effects of the sensorless vector control correction device 220 according to this embodiment will be described. The sensorless vector control correction device 220 according to this embodiment has a system for sensor-equipped speed control so as to accommodate all of the induction motors 4a to 4d that drive the bridle rolls 2a to 2d. Therefore, even if it is not possible to install speed sensors when updating the bridle roll speed control system, accurate sensorless speed control can be performed.

[0055] In retrofit engineering, conveyance systems and tension control systems using multiple bridle rolls may be used. In the retrofit work for these systems, it is often difficult to determine whether or not a speed sensor should be installed until the work is at an advanced stage. In this embodiment, by providing a sensorless vector control correction device 220 for each speed control system, it is possible to select a system for performing sensorless speed control depending on the configuration of the speed control system. Therefore, even in an advanced stage of the retrofit engineering work, it is easy to apply the sensorless vector control correction device 220 to achieve high-precision sensorless speed control, and it is also possible to reduce the work time required for the retrofit engineering work.

[0056] In this way, a sensorless vector control correction device that can perform highly accurate sensorless vector control in drive control of the bridle roll can be realized.

[0057] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0058] 2a to 2d... Bridle rolls, 4a to 4d... Induction motors, 6a to 6d... Speed ​​sensors, 10a to 10d... Drive devices, 11a to 11d... Drive sections, 12a to 12d... Torque controllers, 14a to 14d... Speed ​​controllers, 16a to 16d... Sensorless controllers, 20, 220... Sensorless vector control correction devices, 22... Correction value calculation section, 100, 200... Control devices, 224... Selection section

Claims

1. A plurality of bridle rolls; a plurality of induction motors that respectively drive the plurality of bridle rolls; At least one induction motor among the plurality of induction motors is a sensor-equipped speed-controlled induction motor; Among the plurality of induction motors, the remaining induction motors are subjected to sensorless speed control; at least one drive device that controls the at least one induction motor; a remaining drive device for controlling the remaining induction motor; A control device for a bridle roll drive control system including: a speed feedback estimate value correction calculation means for calculating a correction value for the remaining speed feedback estimate based on at least one speed feedback estimate calculated for the at least one induction motor using at least one drive current detected by the at least one drive device, remaining speed feedback estimates calculated for the remaining induction motors using remaining drive currents detected by the remaining drive devices, and at least one actual speed feedback measurement value for the at least one induction motor, and for calculating and outputting a corrected remaining speed feedback estimate; the speed feedback estimate value correction calculation means calculates a difference between the at least one speed feedback actual measurement value and the at least one speed feedback estimate value, and calculates the corrected remaining speed feedback estimate value based on a statistical calculation of the difference.

2. 2. The control device according to claim 1, wherein the speed feedback estimated value correction calculation means calculates an arithmetic mean of the difference to calculate a correction value, and adds the correction value to the remaining speed feedback estimated value to calculate the corrected remaining speed feedback estimated value.

3. A sensorless vector control correction device that supplies a speed feedback estimated value for sensorless speed control to a control device that controls a plurality of drive devices that respectively control a plurality of induction motors that drive a plurality of bridle rolls, A plurality of speed feedback actual measurement values ​​corresponding to the plurality of induction motors can be inputted, respectively; a plurality of velocity feedback estimated values ​​that are set to correspond to the plurality of feedback actual measurement values, respectively, can be input; a selection means for selecting at least one velocity feedback actual measurement value from the plurality of velocity feedback actual measurement values; a correction value calculation means for calculating a difference between the at least one velocity feedback actual measurement value selected by the selection means and at least one velocity feedback estimated value corresponding to the at least one velocity feedback actual measurement value among the plurality of velocity feedback estimated values, and for performing a statistical calculation of the difference; Equipped with a sensorless vector control correction device that calculates correction values ​​for remaining speed feedback estimate values ​​other than the at least one speed feedback estimate value among the plurality of speed feedback estimate values ​​based on the statistical calculation of the differences, calculates the corrected remaining speed feedback estimate values, and outputs the corrected remaining speed feedback estimate values ​​as speed feedback estimate values ​​for the sensorless speed control.

Images