JP2018125955A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a motor control device capable of improving the estimation accuracy of a magnetic pole position in a high frequency superimposition method. SOLUTION: This is a motor control device 2 for controlling a motor 1 having a salient pole, and an estimation unit 5 for estimating a magnetic pole position of the motor based on a motor current, and a first AC voltage command for driving the motor. High-frequency voltage command generator 7 which is a high-frequency voltage command generator that generates a second AC voltage command having a frequency higher than the frequency of the first AC voltage command and a second AC voltage command having a frequency higher than the frequency of the first AC voltage command. A high-frequency voltage correction unit 8 and an addition unit 9 that generates a voltage command by weighting a second AC voltage command to a first AC voltage command are provided. [Selection diagram] Fig. 1

Description

  The present invention relates to a motor control device that controls a motor.

  When the motor is controlled with high accuracy, it is necessary to generate a rotating magnetic flux according to the magnetic pole position of the rotor. However, when a position sensor is used for detecting the magnetic pole position, various problems such as high cost, vulnerability to vibration and heat, increase in motor size, increase in wiring, and limitation on wiring length arise.

  For this reason, a method for detecting the magnetic pole position without using a position sensor has been developed. As a method for detecting the magnetic pole position, a method called sensorless vector control is widely known. In sensorless vector control, the magnetic pole position of the rotor is estimated using an induced voltage during rotation due to the magnetic flux of the permanent magnet. However, this method has a problem in that it is difficult to detect or estimate the induced voltage at low speed when the induced voltage is small, and the magnetic pole position detection accuracy and the speed estimation accuracy of the rotor deteriorate.

  To solve this problem for motors with magnetic saliency, a high-frequency voltage for position estimation is superimposed on the fundamental wave output by the motor controller to control the rotation of the motor. There is a method called a high-frequency superposition method for estimating the magnetic pole position of the rotor. Patent Document 1 discloses a technique for suppressing a phase estimation error in sensorless vector control by adopting a high-frequency superposition method.

  In the technique described in Patent Document 1, the motor control device performs control to keep the amplitude of the high-frequency current constant when output to the motor. However, as the wiring length between the motor control device and the motor increases, the amplitude of the high-frequency current flowing through the motor decreases due to the influence of stray capacitance. For this reason, when the wiring length between the motor control device and the motor is increased, the amplitude of the high-frequency current flowing through the motor is reduced, and the magnetic pole position estimation accuracy is reduced in the technique described in Patent Document 1.

JP 2007-124835 A

  As described above, in the technique described in Patent Document 1, the magnetic pole position estimation accuracy decreases.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a motor control device that can improve the estimation accuracy of the magnetic pole position in the high-frequency superposition method.

  In order to solve the above-described problems and achieve the object, a motor control device according to the present invention is a motor control device that controls a motor by being connected to a motor having saliency by wiring. An estimation unit that estimates the magnetic pole position of the motor based on the flowing motor current is provided. The motor control device further generates a command arithmetic unit that generates a first AC voltage command to drive the motor, and a second AC voltage command having a frequency higher than the frequency of the first AC voltage command based on the wiring information. And a high-frequency voltage command generation unit that generates the drive voltage command by superimposing the second AC voltage command on the first AC voltage command.

  According to the motor control device of the present invention, it is possible to improve the estimation accuracy of the magnetic pole position by the high frequency superposition method.

1 is a diagram illustrating a configuration example of a motor control device according to a first embodiment. FIG. 3 is a diagram illustrating a configuration example of a control circuit according to the first embodiment. The flowchart which shows an example of the acquisition procedure of the relationship between the wiring length of the high frequency voltage and the high frequency current in the motor control apparatus of Embodiment 1. The figure which shows an example of the measurement result obtained by step S1 of FIG. 3, and Idh (L). The figure which shows an example of the adjustment amount and (DELTA) Vdh (L) determined so that the difference of a reference value and estimated phase (theta) 0 may become below a desired magnetic pole position estimation precision.

  Hereinafter, a motor control device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a motor control device according to the first embodiment of the present invention. The motor control device 2 according to the first embodiment controls the motor 1 by sensorless vector control while performing phase estimation error correction by a high frequency superposition method. Here, sensorless vector control refers to the magnetic pole position and rotation of the motor 1 from the induced voltage of the motor 1 without attaching a position sensor to the motor 1 or using it as a position sensor even if the sensor is attached to the motor 1. In this method, the speed is estimated and the motor speed is controlled so that the estimated speed matches the speed command.

  The motor 1 is, for example, an embedded magnet type synchronous motor in which a permanent magnet is embedded in a rotor. Although not shown, the rotor of the motor 1 has a permanent magnet and a rotor core having a higher permeability than the permanent magnet. The material of the rotor core is, for example, silicon steel. The permanent magnet is exemplified by a ferrite magnet and a neodymium magnet. Hereinafter, the direction of the magnetic flux generated by the magnetic poles of the rotor of the motor 1, that is, the central axis of the permanent magnet is defined as d-axis, and the axis electrically and magnetically orthogonal to the d-axis is defined as q-axis. The d-axis is also called a magnetic flux axis, and the q-axis is also called a torque axis. The orthogonal biaxial coordinate system using the d-axis and the q-axis is a coordinate system that rotates together with the rotor.

  In the motor 1, the flux linkage due to the d-axis current id, which is the d-axis component of the current flowing through the motor 1, is limited because there is a permanent magnet having a lower permeability than the rotor core, whereas the motor 1 The flux linkage caused by the q-axis current iq, which is the q-axis component of the current flowing through 1, passes through the rotor core having a higher permeability than the magnet. For this reason, the flux linkage caused by the q-axis current iq is larger than the flux linkage caused by the d-axis current id. Therefore, in the normal operation, the motor 1 has a d-axis magnetic resistance larger than a q-axis magnetic resistance, and a d-axis inductance Ld smaller than a q-axis inductance Lq. That is, the salient pole ratio Lq / Ld, which is the ratio of the q-axis inductance Lq to the d-axis inductance Ld, is larger than 1. Thus, the motor 1 is a motor having saliency.

  The motor control device 2 according to the first embodiment includes a voltage application unit 3, a current detection unit 4, an estimation unit 5, and a control unit 6. With this configuration, the motor control device 2 uses the fact that the salient pole ratio of the motor 1 during steady operation is a value larger than 1, that is, uses the saliency of the motor 1 to provide the magnetic poles of the rotor. The phase indicating the position is estimated, and the driving speed of the motor 1 is controlled using the estimated magnetic pole position. The magnetic pole position of the rotor corresponds to the rotational position of the motor 1.

  The voltage application unit 3 is a power converter such as a PWM (Pulse Width Modulation) type inverter. Below, the example in which the voltage application part 3 is a PWM system inverter is demonstrated. The voltage application unit 3 converts the DC voltage Vdc into a PWM-modulated three-phase AC voltage based on the drive voltage commands Vup *, Vvp * and Vwp *, which are outputs from the control unit 6, and applies them to the motor 1. Vup *, Vvp * and Vwp * are drive voltage commands corresponding to the U phase, V phase and W phase of the motor 1, respectively. Since the operation of the voltage application unit 3 may be the same as that of a general PWM inverter, detailed description thereof is omitted.

  In the present embodiment, the current detection unit 4 is mounted on the motor control device 2 and measures motor currents iu, iv, and iw flowing through the motor 1, respectively. The wirings 21, 22, and 23 are power lines that connect the terminals of the motor 1 and the external connection terminals of the motor control device 2. That is, the current detection unit 4 detects the motor current on the side opposite to the motor end flowing through the wirings 21, 22, and 23. The motor end indicates a location close to the motor 1 and is, for example, a location where the distance from the motor is a certain value or less. The wiring 21, the wiring 22, and the wiring 23 correspond to the U phase, the V phase, and the W phase of the motor 1, respectively. The lengths of the wirings 21, 22, and 23 are assumed to be the same. The current detection unit 4 is, for example, a current transformer. The current detection unit 4 outputs the measurement result to the control unit 6. In addition, although the example which detects the electric current of three phases is shown in FIG. 1, the electric current of arbitrary two phases is detected, and the electric current of the remaining phases is calculated by using the fact that the motor current is three-phase equilibrium. You may ask for it.

  The controller 6 performs sensorless vector control while performing phase estimation error correction by a high frequency superposition method. The control unit 6 includes a high frequency voltage generator 7, a high frequency voltage correction unit 8, an addition unit 9, a coordinate converter 10, a filter 11, a drive voltage command calculation unit 12, and a d-axis current command calculation unit 13. Q-axis current command calculation unit 14. The drive voltage command calculation unit 12 includes a current controller 12a and a coordinate converter 12b.

  The high-frequency voltage generator 7 generates high-frequency voltage commands Vuh, Vvh, Vwh according to the high-frequency voltage commands Vdh *, Vqh * input from the high-frequency voltage correction unit 8 described later, and outputs them to the adder unit 9. That is, the high-frequency voltage generator 7 is a high-frequency voltage generator that generates a high-frequency voltage based on the high-frequency voltage command corrected by the high-frequency voltage corrector 8. The high-frequency voltage commands Vuh, Vvh, and Vwh have the same frequency as the drive control voltage commands Vu *, Vv *, and Vw * output from the coordinate converter 12b in the drive voltage command calculation unit 12 as the first AC voltage command. It is a different second AC voltage command.

  That is, the high-frequency voltage commands Vuh, Vvh, and Vwh are commands for generating a high-frequency voltage having a frequency higher than the frequency of the drive voltage command. In the present embodiment, the high-frequency voltage correction unit 8 and the high-frequency voltage generator 7 for generating a high-frequency voltage command are collectively referred to as a high-frequency voltage command generation unit. The high-frequency voltage commands Vuh, Vvh, and Vwh may be any frequency that is different from the voltage commands Vu *, Vv *, and Vw * for drive control. In the first embodiment, the three-phase high-frequency voltage is used. It is a directive.

  The high-frequency voltage correction unit 8 is configured to generate a high-frequency voltage command Vdh *, Vdh *, Vqh taking into account the influence of the wiring length based on the high-frequency voltage commands Vdh, Vqh input from the outside and the wiring length L, which is the length of the wirings 21, 22, 23. Vqh * is output. That is, the high frequency voltage correction unit 8 is a correction unit that corrects the high frequency voltage commands Vdh and Vqh based on the wiring length. Details of the processing of the high-frequency voltage correction unit 8 will be described later.

  The adding unit 9 outputs the three-phase high-frequency voltage commands Vuh, Vvh, and Vwh output from the high-frequency voltage generator 7 to the drive control voltage command Vu * output from the coordinate converter 12b in the drive voltage command calculation unit 12. , Vv *, Vw * and output to the voltage application unit 3 as drive voltage commands Vup *, Vvp *, Vwp *. That is, the adder 9 generates drive voltage commands Vup *, Vvp *, Vwp * which are voltage commands by adding the high frequency voltage to the drive voltage command.

  The voltage application unit 3 generates three-phase AC power based on the drive voltage commands Vup *, Vvp *, Vwp * of the motor 1 and applies it to the motor 1. That is, the voltage application unit 3 generates a voltage corresponding to the drive voltage commands Vup *, Vvp *, and Vwp * that are voltage commands output from the addition unit 9 and applies the generated voltage to the motor 1. As a result, the motor currents iu, iv, iw detected by the current detector 4 include high-frequency currents iuh, ivh, iwh having the same frequency components as the high-frequency voltage commands Vuh, Vvh, Vwh. Since the motor 1 has saliency as described above, the inductance changes according to the rotor position. For this reason, the amplitudes of the high-frequency currents iuh, ivh, iwh included in the motor currents iu, iv, iw change according to the rotor position of the motor 1.

  The coordinate converter 10 converts the motor currents iu, iv, iw including the high-frequency currents iuh, ivh, iwh whose amplitudes change as described above into rotational orthogonal biaxial coordinates composed of the d axis and the q axis. The coordinates are converted into control currents idf and iqf in the system, and the control currents idf and iqf are output to the filter 11. A rotation orthogonal biaxial coordinate system composed of the d axis and the q axis is hereinafter referred to as a dq coordinate system. It rotates in synchronization with the estimated phase θ0.

  The filter 11 extracts high-frequency currents idh and iqh having the same frequency components as the high-frequency voltage commands Vdh and Vqh input from the outside to the high-frequency voltage generator 7 from the control currents idf and iqf. Further, the filter 11 removes the extracted high-frequency currents idh and iqh from the control currents idf and iqf to generate control current vectors id and iq. The filter 11 outputs the high-frequency currents idh and iqh to the estimation unit 5, and outputs the control current vectors id and iq to the estimation unit 5 and the current controller 12a. The filter 11 can also output the high-frequency currents idh and iqh to the high-frequency voltage correction unit 8. The filter 11 is composed of, for example, a band pass filter, a notch filter, or the like.

  The estimation unit 5 estimates the phase of the motor 1 based on the high frequency currents idh and iqh and the control current vectors id and iq output from the filter 11 and the drive voltage commands Vd * and Vq * output from the current controller 12a. θ0 and estimated speed ωr0 are calculated. That is, the estimation unit 5 estimates the magnetic pole position of the motor based on the motor current. As a method for calculating the estimated phase θ0 and the estimated speed ωr0 in the estimation unit 5, a generally used method can be used, and any method may be used, and thus the detailed description thereof is omitted. The estimation unit 5 outputs the estimated phase θ0 to the coordinate converters 10 and 12b, and outputs the estimated speed ωr0 to the d-axis current command calculation unit 13 and the q-axis current command calculation unit 14.

  The q-axis current command calculation unit 14 calculates a current control vector command iq * by proportional-integral control so that the speed command ω * input from the outside and the estimated speed ωr0 input from the estimation unit 5 coincide with each other. Control vector command iq * is output to q-axis current command calculation unit 14 and current controller 12a. Note that the method of calculating the current control vector command iq * in the q-axis current command calculation unit 14 is not limited to proportional-integral control.

  The d-axis current command calculation unit 13 outputs the current control vector command id * to the current controller 12a as zero or a constant value near zero in order to realize the estimation of the magnetic pole position by sensorless vector control by the high frequency superposition method. The motor control device 2 may be capable of executing both sensorless vector control by the high frequency superimposition method and sensorless vector control not by the high frequency superimposition method depending on the driving conditions.

  The current controller 12a of the drive voltage command calculation unit 12 performs the drive voltage command Vd * by proportional integral control so that the control current vector commands id * and iq * and the control current vectors id and iq output from the filter 11 match. , Vq * is calculated. Note that the method of calculating the drive voltage commands Vd * and Vq * in the current controller 12a is not limited to proportional-integral control. The current controller 12a outputs the drive voltage commands Vd * and Vq * to the coordinate converter 12b and the estimation unit 5.

  The coordinate converter 12b of the drive voltage command calculation unit 12 converts the input drive voltage commands Vd * and Vq * into the UVW three-phase coordinate system based on the estimated phase θ0, and a second value that is the converted value. Drive voltage commands Vu *, Vv *, Vw * are output to the adder 9. High frequency voltage commands Vuh, Vvh, Vwh are superimposed on the second drive voltage commands Vu *, Vv *, Vw * by the adder 9 to become drive voltage commands Vup *, Vvp *, Vwp *.

  As described above, the drive voltage command calculation unit 12 is a command calculation unit that generates a drive voltage command for driving the motor 1 based on the magnetic pole position and the motor current estimated by the estimation unit 5.

  Next, the hardware configuration of each unit constituting the control unit 6 and the estimation unit 5 will be described. Each part and the estimation part 5 which comprise the control part 6 are implement | achieved by the processing circuit. The processing circuit may be an analog circuit or a digital circuit. A part of each part and the estimation part 5 which comprise the control part 6 may be an analog circuit, and others may be a digital circuit. Further, the processing circuit may be dedicated hardware or a control circuit including a processor. When each part which comprises the control part 6, and the estimation part 5 are implement | achieved by the control circuit provided with a processor, a control circuit is the control circuit shown, for example in FIG.

  FIG. 2 is a diagram illustrating a configuration example of the control circuit. The control circuit 100 includes a processor 101 and a memory 102. The processor 101 is a CPU (Central Processing Unit), a microprocessor, or the like. Each unit realized in the control circuit is realized by the processor 101 executing a program stored in the memory 102. The memory 102 is also used as a storage area when a program is executed by the processor 101. The memory 102 corresponds to, for example, a nonvolatile or volatile semiconductor memory such as a random access memory (RAM), a read only memory (ROM), a flash memory, and an erasable programmable read only memory (EPROM).

  Next, a high-frequency voltage correction method in the motor control device 2 of the present embodiment will be described. The motor control device 2 according to the present embodiment corrects the high frequency voltage using a calculation formula corresponding to the wiring lengths of the wirings 21, 22, and 23. For this purpose, the motor control device 2 first acquires the relationship between the wiring length and the high-frequency current. FIG. 3 is a flowchart illustrating an example of a procedure for acquiring the relationship between the wiring length of the high-frequency voltage and the high-frequency current in the motor control device 2 according to the first embodiment. The motor control device 2 has an acquisition mode that is an operation mode for acquiring the relationship between the wiring length and the high-frequency current, and a correction mode that performs correction based on the result of acquiring the relationship between the wiring length and the high-frequency current. When the acquisition mode is set, the process shown in FIG. 3 is performed. In the acquisition mode, the current on the motor end side of the wiring is detected using a current detector external to the motor control device 6. That is, a high-frequency current in which an error has occurred due to the influence of wiring stray capacitance is detected. As shown in FIG. 3, first, the motor control device 2 measures the high-frequency current at each motor end in the case of a plurality of wiring lengths in an unloaded state (step S1).

  Specifically, in step S1, first, the wiring lengths of the wirings 21, 22, and 23 are set to the first wiring length by the operator. The first wiring length is, for example, 0 m. In this state, the motor control device 2 operates in a state where no load is applied to the motor 1, and the measurement result detected by the external current detector at this time is input to the coordinate converter 10, and the coordinate converter 10 is controlled. The currents idf and iqf are output to the filter 11. The filter 11 extracts the high frequency currents idh and iqh from the control currents idf and iqf, and outputs them to the high frequency voltage correction unit 8. Further, the first wiring length is input from the outside to the high-frequency voltage correction unit 8. The high-frequency voltage correction unit 8 associates the first wiring length with the high-frequency currents idh and iqh and holds them as measurement results. When the wiring is 0 m, the current detector 4 may be used instead of the external current detector.

  Next, the wiring length of the wirings 21, 22, and 23 is set to the second wiring length by the operator. The second wiring length is longer than the first wiring length, for example, 50 m. In this state, the motor control device 2 operates in a state where no load is applied to the motor 1. As a result, the high-frequency currents idh and iqh are output from the filter 11 to the high-frequency voltage correction unit 8 as in the case where the wirings 21, 22 and 23 are set to the first wiring length. Further, the second wiring length is input from the outside to the high-frequency voltage correction unit 8. The high-frequency voltage correction unit 8 associates the second wiring length with the high-frequency currents idh and iqh and holds them as measurement results.

  Note that the input of the first wiring length and the second wiring length to the motor control device 2 may be performed by a user via an information processing device (not shown) connected to the motor control device 2, or motor control. The device may be provided with input means such as a keyboard and a touch panel for receiving input, and may be input from the input means. The input of the first wiring length and the second wiring length to the motor control device 2 is not limited to these examples, and may be performed by any method.

Returning to the description of FIG. 3, after step S1, the motor control device 2 approximates the high-frequency current at the motor end with a linear function of the wiring length based on the measurement result (step S2). Specifically, based on the measurement result in the case of the first wiring length and the measurement result in the case of the second wiring length, the high-frequency voltage correction unit 8 converts the relationship between the wiring lengths as a function of the high-frequency current at the motor end. Approximate. As the function approximation method, since the number of measurement points is two in this example, a method of expressing a straight line connecting the two points by a linear function can be used. In this case, when the first wiring length is 0 m and the second wiring length is 50 m, the d-axis and q-axis components of the motor end high-frequency current approximated by a linear function of the wiring length L are idh ( When L) and iqh (L), idh (L) is expressed by the following equation (1). Idh0 is the d-axis component idh of the high-frequency current at the motor end detected by the external current detector when the wiring length is 0 m, and Idh50 is the external current detection when the wiring length is 50 m. The d-axis component idh of the high-frequency current at the motor end detected by the detector.
Idh (L) = (Idh50−Idh0) / 50 × L + Idh0 (1)

  In the above example, the slope when idh (L) is approximated by a linear function of the wiring length L is (Idh50−Idh0) / 50, and the intercept is Idh0. Even when the first wiring length and the second wiring length are other than the values described above, idh (L) can be determined by obtaining the slope and intercept of a straight line connecting two points. FIG. 4 is a diagram showing an example of the measurement result and Idh (L) obtained in step S1 of FIG. FIG. 4 shows an example in which the first wiring length is 0 m and the second wiring length is 50 m. In FIG. 4, the horizontal axis is the wiring length, and the vertical axis is the d-axis component of the high-frequency current at the motor end. As shown in FIG. 4, a straight line 203 connecting the two measurement points 201 and 202 is Idh (L) expressed by the above equation (1).

Returning to the description of FIG. 3, the motor control device 2 determines a calculation formula for correcting the high-frequency voltage command using the coefficient obtained by approximation (step S <b> 3), and ends the operation in the acquisition mode. Specifically, the high-frequency voltage correction unit 8 determines a calculation formula for obtaining the d-axis high-frequency voltage command Vdh * in consideration of the influence of the wiring length as the above-described formula (1) and the following formula (2). To do. Idh (0) is Idh (L) shown in the above formula (1) when the wiring length L is 0.
Vdh * = Idh (0) / Idh (L) × Vdh (2)

The high-frequency voltage correction unit 8 also determines the calculation formula for obtaining the q-axis high-frequency voltage command Vqh * as in the following formulas (3) and (4), similarly to the d-axis.
Iqh (L) = (Iqh50−Iqh0) / 50 × L + Iqh0 (3)
Vqh * = Iqh (0) / Iqh (L) × Vqh (4)
However, in the high frequency superimposition method, there is a method in which a high frequency voltage is applied only to the d axis. In this case, Vqh = 0 and Vqh * = 0.

  In step S3, the high-frequency current at the motor end may be measured for each of the three or more wiring lengths. In this case as well, a linear approximation formula can be determined by the least square method or the like.

  With the above operation, the calculation formula used when the high-frequency voltage correction unit 8 corrects the high-frequency voltage command is determined. In the correction mode, the high-frequency voltage correction unit 8 uses the calculation formula determined in the acquisition mode based on the input wiring length L, for example, the calculation formulas of Formulas (1) to (4) and And the corrected high-frequency voltage command is output to the high-frequency voltage generator 7. Note that the input of the wiring length L may be performed at a fixed period, or while the wiring length L does not change, the same calculation formula can be used, so that the input of the wiring length L is performed when the wiring length changes. It may be broken. The wiring length L input in the correction mode is the wiring length when the motor 1 is operating. As described above, the high frequency voltage correction unit 8 corrects the high frequency voltage command based on the information indicating the relationship between the wiring length and the high frequency current and the wiring length when the motor 1 is operated.

  In the example described above, the motor control device 2 performs the processing in the acquisition mode shown in FIG. 3, but the processing in the acquisition mode is performed by an information processing device (not shown) that is different from the motor control device 2. It may be done. In this case, the calculation formula determined by the information processing apparatus is set in the high-frequency voltage correction unit 8. In this case, the control current vectors id and iq may be input to the information processing apparatus, and the information processing apparatus may calculate the above calculation formula, or the high frequency current at the motor end may be input by the information processing apparatus. After the information processing apparatus performs the same processing as the coordinate converter 10 and the filter 11, the above calculation formula may be calculated.

  In the present embodiment, the high-frequency voltage correction unit 8 performs correction based on the wiring length L, but may perform correction based on other wiring information. For example, wiring stray capacitance may be used as wiring information.

  As described above, according to the first embodiment, the relationship between the wiring length and the high-frequency current at the motor end is obtained in advance, and the high-frequency voltage command is corrected based on this relationship and the wiring length. For this reason, even when a voltage error due to stray capacitance occurs during long wiring, high-frequency superposition type sensorless vector control can be performed without reducing the magnetic pole position estimation accuracy. Further, even when the wiring length is changed due to the change in configuration, the magnetic pole position estimation accuracy can be maintained with high accuracy.

Embodiment 2. FIG.
Next, a high-frequency voltage correction method in the motor control device according to the second embodiment of the present invention will be described. Since the configuration of the motor control device 2 of the present embodiment is the same as that of the first embodiment, redundant description is omitted. However, the estimated phase θ0 calculated by the estimation unit 5 is also input to the high-frequency voltage correction unit 8, and a reference value for evaluating the magnetic pole position estimation accuracy described later is input to the high-frequency voltage correction unit 8. Hereinafter, differences from the first embodiment will be described.

  In the present embodiment, in the acquisition mode, the wirings 21, 22, and 23 are set to a third wiring length that is a wiring length that is not 0 m, and the motor control device 2 operates the motor 1 with no load. In this state, the high-frequency voltage correction unit 8 adjusts the high-frequency voltage command so that a desired magnetic pole position estimation accuracy can be obtained. Specifically, the high-frequency voltage correction unit 8 calculates the difference between the reference value and the estimated phase θ0 calculated by the estimation unit 5, and the absolute value of this difference is the desired magnetic pole position for each of the d-axis and the q-axis. The adjustment amount for the high-frequency voltage is determined so as to be less than the estimated accuracy. That is, when the d-axis adjustment amount is ΔVdh and the q-axis adjustment amount is ΔVqh, the high-frequency voltage correction unit 8 outputs Vdh + ΔVdh, Vqh + ΔVqh to the high-frequency voltage generator 7, and the above difference is the desired magnetic pole position. ΔVdh and ΔVqh are determined so as to be less than the estimation accuracy.

Next, the high frequency voltage correction unit 8 determines a calculation formula for calculating the adjustment amount as a function of the wiring length L based on the calculated adjustment amount. Here, the calculation formula is determined on the assumption that the adjustment amount is directly proportional to the wiring length. For example, the third wiring length is 50 m, and the d-axis adjustment amount determined by the high-frequency voltage correction unit 8 so that the difference between the reference value and the estimated phase θ0 is equal to or less than the desired magnetic pole position estimation accuracy is ΔVdh50. At this time, the high-frequency voltage correction unit 8 determines a calculation formula for calculating the adjustment amount as a function of the wiring length L to the following formula (5).
ΔVdh (L) = Vdh50 / 50 × L (5)

Further, the high-frequency voltage correction unit 8 determines a calculation formula for calculating the high-frequency voltage command Vdh * in consideration of the influence of the wiring length to the above-described formula (5) and the following formula (6).
Vdh * = Vdh + ΔVdh (L) (6)

Similarly, for the q-axis, the high-frequency voltage correction unit 8 determines a calculation formula for calculating the high-frequency voltage command Vdh * in consideration of the influence of the wiring length as the following formulas (7) and (8).
ΔVqh (L) = Vqh50 / 50 × L (7)
Vqh * = Vqh + ΔVqh (L) (8)

  FIG. 5 is a diagram illustrating an example of the adjustment amount and ΔVdh (L) determined so that the difference between the reference value and the estimated phase θ0 is equal to or less than the desired magnetic pole position estimation accuracy. FIG. 5 shows an example in which the third wiring length is 50 m. In FIG. 4, the horizontal axis represents the wiring length, and the vertical axis represents the adjustment amount of the high-frequency voltage. As shown in FIG. 5, the straight line 302 connecting the adjustment amount 301 and the origin determined so that the difference between the reference value and the estimated phase θ0 is equal to or less than the desired magnetic pole position estimation accuracy is expressed by the above equation (5). The indicated ΔVdh (L).

  With the above operation, the calculation formula used when the high-frequency voltage correction unit 8 corrects the high-frequency voltage command is determined. In the correction mode, the high-frequency voltage correction unit 8 uses the calculation formula determined in the acquisition mode based on the input wiring length L, for example, the calculation formulas of formulas (5) to (8) to And the corrected high-frequency voltage command is output to the high-frequency voltage generator 7. Note that the input of the wiring length L may be performed at a fixed period, or while the wiring length L does not change, the same calculation formula can be used, so that the input of the wiring length L is performed when the wiring length changes. It may be broken. The wiring length L input in the correction mode is the wiring length when the motor 1 is operating. As described above, the high-frequency voltage correction unit 8 according to the second embodiment includes information indicating the relationship between the wiring length and the correction amount, that is, the calculation formula determined in the acquisition mode, and the wiring length when the motor 1 is operated. Based on the above, the high frequency voltage command is corrected.

  As described above, according to the second embodiment, the relationship between the wiring length and the adjustment amount satisfying the desired magnetic pole position estimation accuracy of the high-frequency voltage is obtained in advance, and the high-frequency voltage command is based on this relationship and the wiring information. Was corrected. For this reason, even when a voltage error due to stray capacitance occurs during long wiring, high-frequency superposition type sensorless vector control can be performed without reducing the magnetic pole position estimation accuracy. Also, the magnetic pole position estimation accuracy can be kept high even when the wiring information is changed due to a change in configuration.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Motor, 2 Motor control apparatus, 3 Voltage application part, 4 Current detection part, 5 Estimation part, 6 Control part, 7 High frequency voltage generator, 8 High frequency voltage correction part, 9 Addition part, 10 Coordinate converter, 11 Filter, 12 drive voltage command calculation unit, 12a current controller, 12b coordinate converter, 13 d-axis current command calculation unit, 14 q-axis current command calculation unit.

Claims (4)

A motor control device that controls the motor by being connected to a motor having saliency by wiring,
An estimation unit that estimates a magnetic pole position of the motor based on a motor current flowing in the motor;
A command calculation unit for generating a first AC voltage command for driving the motor;
A high-frequency voltage command generation unit that generates a second AC voltage command having a frequency higher than the frequency of the first AC voltage command based on wiring information that is information related to the wiring;
An adder that generates a drive voltage command by superimposing the second AC voltage command on the first AC voltage command;
A motor control device comprising:   The motor control apparatus according to claim 1, wherein the wiring information is a wiring length connecting the motor and the motor control apparatus.   The high-frequency voltage command generation unit generates the high-frequency voltage command from a relationship between a pre-measured high-frequency current having the same frequency as the second AC voltage command and the wiring information. Or the motor control apparatus of 2.   The high-frequency voltage command generation unit generates the high-frequency voltage command from a relationship between an adjustment amount that is measured in advance and adjusts the second AC voltage command based on the wiring information, and the wiring information. The motor control device according to claim 1, wherein the motor control device is a motor control device.

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