JP6832726B2 - Motor control device - Google Patents

Description

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

When controlling the motor with high accuracy, it is necessary to generate a rotating magnetic flux according to the position of the magnetic pole of the rotor. However, when a position sensor is used to detect the position of a magnetic pole, various problems such as high cost, vulnerability to vibration and heat, large size of motor, increase in wiring, and restriction of wiring length occur.

Therefore, a method of detecting the magnetic pole position without using a position sensor has been conventionally developed. As a method of 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 the induced voltage during rotation due to the magnetic flux of the permanent magnet. However, this method has a problem that it becomes difficult to detect or estimate the induced voltage at a low speed when the induced voltage is small, and the accuracy of detecting the magnetic pole position of the rotor and the accuracy of estimating the speed deteriorate.

As a method of solving this problem for a motor having magnetic salient poles, 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, and the detected current is used. There is a method called a high-frequency superposition method that estimates the magnetic pole position of the rotor. Patent Document 1 discloses a technique of suppressing a phase estimation error in sensorless vector control by adopting a high frequency superimposition method.

In the technique described in Patent Document 1, the motor control device controls to keep the amplitude of the high frequency current when outputting to the motor constant. However, as the wiring length between the motor control device and the motor becomes longer, the amplitude of the high frequency current flowing through the motor decreases due to the influence of stray capacitance. Therefore, when the wiring length between the motor control device and the motor becomes long, the amplitude of the high-frequency current flowing through the motor decreases, so that the magnetic pole position estimation accuracy decreases in the technique described in Patent Document 1.

JP-A-2007-124835

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

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 capable of improving the estimation accuracy of the magnetic pole position in the high-frequency superposition method.

In order to solve the above-mentioned problems and achieve the object, the motor control device according to the present invention is a motor control device that controls a motor by being connected to a motor having a salient polarity by wiring, and is a motor. It is provided with an estimation unit that estimates the magnetic pole position of the motor based on the flowing motor current. The motor control apparatus may further include a calculation unit for generating a first AC voltage instruction to drive the motor, the second AC voltage instruction having a frequency higher than the frequency of the first AC voltage command, the wiring length of the wiring Alternatively, it includes a high-frequency voltage command generation unit that generates a high-frequency voltage command based on the floating capacitance of the wiring, and an addition unit that generates a drive voltage command by superimposing a second AC voltage command on the first AC voltage command.

According to the motor control device according to the present invention, there is an effect that the estimation accuracy of the magnetic pole position by the high frequency superimposition method can be improved.

The figure which shows the structural example of the motor control device which concerns on Embodiment 1. The figure which shows the structural example of the control circuit of Embodiment 1. A flowchart showing an example of an acquisition procedure of the relationship between the wiring length of the high frequency voltage and the high frequency current in the motor control device of the first embodiment. The figure which shows an example of the measurement result and Idh (L) obtained in step S1 of FIG. The figure which shows an example of the adjustment amount and ΔVdh (L) determined so that the difference between a reference value and an estimated phase θ0 is less than a desired magnetic pole position estimation accuracy.

Hereinafter, the motor control device according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a motor control device according to a first embodiment of the present invention. The motor control device 2 of the first embodiment controls the motor 1 by sensorless vector control while performing phase estimation error correction by the high frequency superimposition method. Here, sensorless vector control means the position and rotation of the magnetic poles of the motor 1 from the induced voltage of the motor 1 without attaching a position sensor to the motor 1 or using the sensor as a position sensor even if the sensor is attached to the motor 1. This is a method of estimating the speed and controlling the motor speed 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 inside a rotor. Although not shown, the rotor of the motor 1 has a permanent magnet and a rotor core having a higher magnetic permeability than the permanent magnet. The material of the rotor core is, for example, silicon steel. Examples of permanent magnets include ferrite magnets and neodymium magnets. Hereinafter, the direction of the magnetic flux created by the magnetic poles of the rotor of the motor 1, that is, the central axis of the permanent magnet is defined as the d-axis, and the axis electrically and magnetically orthogonal to the d-axis is defined as the q-axis. The d-axis is also called the magnetic flux axis, and the q-axis is also called the torque axis. The orthogonal two-axis coordinate system with the d-axis and the q-axis is a coordinate system that rotates with the rotor.

In the motor 1, the interlinkage magnetic flux due to the d-axis current id, which is the d-axis component of the current flowing through the motor 1, is limited because a permanent magnet having a magnetic permeability lower than that of the rotor core is in the middle. The interlinkage magnetic flux due to 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 magnetic permeability than the magnet. Therefore, the interlinkage magnetic flux due to the q-axis current iq is larger than the interlinkage magnetic flux due to the d-axis current id. Therefore, in the steady operation of the motor 1, the d-axis magnetic resistance becomes larger than the q-axis magnetic resistance, and the d-axis inductance Ld becomes smaller than the 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 a value larger than 1. As described above, the motor 1 is a motor having a salient polarity.

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 utilizes the fact that the salient pole ratio of the motor 1 during steady operation is a value larger than 1, that is, the salient pole of the motor 1, and 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 including a PWM (Pulse Width Modulation) type inverter. Hereinafter, an example in which the voltage application unit 3 is a PWM type inverter will be described. 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 the outputs of the control unit 6, and applies the voltage 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 type inverter, detailed description thereof will be omitted.

In the present embodiment, the current detection unit 4 is mounted on the motor control device 2 and measures the motor currents iu, iv, and iwa flowing through the motor 1, respectively. Wiring 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 portion close to the motor 1, for example, a portion 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, V phase, and W phase of the motor 1, respectively. It is assumed that the lengths of the wires 21, 22, and 23 are 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. Although FIG. 1 shows an example of detecting a three-phase current, an arbitrary two-phase current is detected, and the current of the remaining phases is calculated by utilizing the fact that the motor current is in three-phase equilibrium. You may ask.

The control unit 6 performs sensorless vector control while performing phase estimation error correction by the high frequency superimposition 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. , The q-axis current command calculation unit 14 is provided. 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 * and Vqh * input from the high frequency voltage correction unit 8 described later, and outputs the high frequency voltage commands to the adding unit 9. That is, the high-frequency voltage generator 7 is a high-frequency voltage generator that generates a high-frequency voltage based on a high-frequency voltage command corrected by the high-frequency voltage correction unit 8. The high-frequency voltage commands Vuh, Vvh, and Vwh have frequencies different from those of the drive control voltage commands Vu *, Vv *, and Vw * output by 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 the 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 different from the drive control voltage commands Vu *, Vv *, and Vw *, but in the first embodiment, the three-phase high-frequency voltage It is a directive.

The high-frequency voltage correction unit 8 is based on the high-frequency voltage commands Vdh and Vqh input from the outside and the wiring length L which is the length of the wirings 21 and 22, 23, and considers the influence of the wiring lengths on the high-frequency voltage commands Vdh *, Outputs Vqh *. 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. The details of the processing of the high frequency voltage correction unit 8 will be described later.

The adder 9 outputs the three-phase high-frequency voltage commands Vuh, Vvh, and Vwh output from the high-frequency voltage generator 7 by the coordinate converter 12b in the drive voltage command calculation unit 12, and the voltage command Vu * for drive control. , Vv *, Vw *, and output to the voltage application unit 3 as drive voltage commands Vup *, Vvp *, Vwp *. That is, the addition unit 9 generates the drive voltage commands Vup *, Vvp *, and 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 *, and Vwp * of the motor 1 and applies the AC power to the motor 1. That is, the voltage application unit 3 generates a voltage corresponding to the drive voltage commands Vup *, Vvp *, and Vwp *, which 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, and iw detected by the current detection unit 4 include high-frequency currents iuh, ivh, and iwh having the same frequency components as the high-frequency voltage commands Vuh, Vvh, and Vwh. Since the motor 1 has a salient polarity as described above, the inductance changes according to the rotor position. Therefore, the amplitudes of the high-frequency currents iuh, ivh, and iwh included in the motor currents iu, iv, and iw change according to the rotor position of the motor 1.

As described above, the coordinate converter 10 rotates the motor currents iu, iv, iw including the high-frequency currents iuh, ivh, iwh whose amplitude changes as described above with the d-axis and the q-axis. The coordinates are converted into the control currents idf and iqf in the system, and the control currents idf and iqf are output to the filter 11. A rotationally orthogonal two-axis coordinate system composed of a d-axis and a 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 current idh and iq 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 high-frequency currents idh and iqh to the high-frequency voltage correction unit 8. The filter 11 is composed of, for example, a bandpass filter, a notch filter, and the like.

The estimation unit 5 estimates the phase of the motor 1 based on the high-frequency current idh, iqh and control current vectors id, iq output by the filter 11 and the drive voltage commands Vd *, Vq * output by the current controller 12a. Calculate θ0 and the estimated speed ωr0. 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 description thereof will be omitted in detail. 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 the current control vector command iq * by proportional integration control so that the speed command ω * input from the outside and the estimated speed ωr0 input from the estimation unit 5 match, and the current The control vector command iq * is output to the q-axis current command calculation unit 14 and the current controller 12a. The calculation method of the current control vector command iq * in the q-axis current command calculation unit 14 is not limited to the proportional integration 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 estimation of the magnetic pole position by sensorless vector control by the high frequency superimposition 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 by the non-high frequency superimposition method depending on the driving conditions.

The current controller 12a of the drive voltage command calculation unit 12 controls the drive voltage command Vd * by proportional integration control so that the control current vector commands id *, iq * and the control current vectors id, iq output from the filter 11 match. , Vq * is calculated. The calculation method of the drive voltage commands Vd * and Vq * in the current controller 12a is not limited to the proportional integration 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 a UVW3 phase coordinate system based on the estimated phase θ0, and is a second value after conversion. The drive voltage commands Vu *, Vv *, and Vw * are output to the adder 9. High-frequency voltage commands Vuh, Vvh, and Vwh are superimposed on the second drive voltage commands Vu *, Vv *, and Vw * in the adding unit 9, and the drive voltage commands Vup *, Vvp *, and Vwp * are obtained.

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 configurations of each unit constituting the control unit 6 and the estimation unit 5 will be described. Each unit and the estimation unit 5 constituting the control unit 6 are realized by a processing circuit. The processing circuit may be an analog circuit or a digital circuit. A part of each unit constituting the control unit 6 and the estimation unit 5 may be an analog circuit, and the other may be a digital circuit. Further, the processing circuit may be dedicated hardware or a control circuit including a processor. When each unit constituting the control unit 6 and the estimation unit 5 are realized by a control circuit including a processor, the control circuit is, for example, the control circuit shown in FIG.

FIG. 2 is a diagram showing a configuration example of a 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 part realized in the control circuit is realized by executing the program stored in the memory 102 by the processor 101. 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 non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, and an EPROM (Erasable Programmable Read Only Memory).

Next, a method for correcting a high frequency voltage in the motor control device 2 of the present embodiment will be described. The motor control device 2 of the present embodiment corrects the high frequency voltage by a calculation formula according to the wiring lengths of the wirings 21, 22, and 23. For this purpose, first, the motor control device 2 acquires the relationship between the wiring length and the high frequency current. FIG. 3 is a flowchart showing an example of an acquisition procedure of the relationship between the wiring length of the high frequency voltage and the high frequency current in the motor control device 2 of the first embodiment. The motor control device 2 has an acquisition mode, which is an operation mode for acquiring the relationship between the wiring length and the high-frequency current, and a correction mode, which performs correction based on the result of acquiring the relationship between the wiring length and the high-frequency current. , The process shown in FIG. 3 is performed when the acquisition mode is set. In the acquisition mode, the current on the motor end side of the wiring is detected by using an external current detector of the motor control device 6. That is, the high frequency current in which an error occurs due to the influence of the stray capacitance of the wiring 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 a no-load state (step S1).

Specifically, in step S1, the operator first sets the wiring lengths of the wirings 21, 22, and 23 to the first wiring length. The first wiring length is, for example, 0 m. In this state, the motor control device 2 operates with no load 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 controlled by the coordinate converter 10. The currents idf and iqf are output to the filter 11. The filter 11 extracts 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 to the high frequency voltage correction unit 8 from the outside. 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 operator sets the wiring lengths of the wirings 21, 22, and 23 to the second wiring length. 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 the motor 1 is not loaded. As a result, the high-frequency current idh and iqh are output from the filter 11 to the high-frequency voltage correction unit 8 in the same manner as when the wirings 21, 22, and 23 are set to the first wiring length. Further, the second wiring length is input to the high frequency voltage correction unit 8 from the outside. 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.

The input of the first wiring length and the second wiring length to the motor control device 2 may be performed by the user via an information processing device (not shown) connected to the motor control device 2, or the motor control. The device may include input means such as a keyboard and a touch panel for receiving input, and input may be performed 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 uses a function of the high-frequency current at the motor end and the relationship of the wiring length. Approximate. As the approximation method of the function, 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 high-frequency current at the motor end approximated by the linear function of L of the wiring length are set to idh (respectively). When L) and iqh (L), idh (L) is represented 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. It is the d-axis component idh of the high-frequency current at the motor end detected by the device.
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 above-mentioned values, the idh (L) can be determined by obtaining the slope and intercept of the straight line connecting the two points. FIG. 4 is a diagram showing an example of the measurement result obtained in step S1 of FIG. 3 and Idh (L). 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, the straight line 203 connecting the two measurement points 201 and 202 is the Idh (L) represented 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 S3), and ends the operation of the acquisition mode. Specifically, the high-frequency voltage correction unit 8 determines the above-mentioned formula (1) and the following formula (2) as calculation formulas for obtaining the d-axis high-frequency voltage command Vdh * in consideration of the influence of the wiring length. To do. Idh (0) is Idh (L) represented by the above equation (1) when the wiring length L is 0.
Vdh * = Idh (0) / Idh (L) × Vdh… (2)

The high-frequency voltage correction unit 8 also defines the calculation formulas for obtaining the high-frequency voltage command Vqh * on the q-axis as 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, but in this case, Vqh = 0 and Vqh * = 0.

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

By the above operation, the calculation formula 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 formulas determined in the acquisition mode based on the input wiring length L, for example, the calculation formulas (1) to (4) to command the high-frequency voltage. Is corrected, and the corrected high-frequency voltage command is output to the high-frequency voltage generator 7. The wiring length L may be input at regular intervals, and the same calculation formula can be used while the wiring length L does not change. Therefore, when the wiring length changes, the wiring length L is input. You may be broken. The wiring length L input in the correction mode is the wiring length during operation of the motor 1. 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 during operation of the motor 1.

Further, in the above-described example, 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) different from the motor control device 2. It may be done. In this case, the calculation formula determined by the information processing device is set in the high frequency voltage correction unit 8. Further, in this case, the control current vectors id and iq may be input to the information processing device, and the information processing device may calculate the above calculation formula, or the high frequency current at the motor end is input by the information processing device. The above calculation formula may be calculated after the information processing apparatus performs the same processing as that of the coordinate converter 10 and the filter 11.

In the present embodiment, the high-frequency voltage correction unit 8 makes corrections based on the wiring length L, but corrections may be made based on other wiring information. For example, the stray capacitance of the wiring may be used as the 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. Therefore, even when a voltage error occurs due to stray capacitance during long wiring, sensorless vector control of the high frequency superimposition method can be performed without lowering the magnetic pole position estimation accuracy. Further, even when the wiring length is changed due to the change in the configuration, the magnetic pole position estimation accuracy can be kept high.

Embodiment 2.
Next, a method for correcting a high frequency voltage 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 will be 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, the points different 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 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 equal to or less than the estimation 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 and 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 equal to or 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 assuming that the adjustment amount is directly proportional to the wiring length. For example, the third wiring length is 50 m, and the adjustment amount of the d-axis 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 the calculation formula for calculating the adjustment amount as a function of the wiring length L by the following formula (5).
ΔVdh (L) = Vdh50 / 50 × L ... (5)

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

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

FIG. 5 is a diagram showing an example of an 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 is the wiring length, and the vertical axis is the adjustment amount of the high frequency voltage. As shown in FIG. 5, a straight line 302 connecting the origin and the adjustment amount 301 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 given by the above equation (5). It is ΔVdh (L) shown.

By the above operation, the calculation formula 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 formulas determined in the acquisition mode based on the input wiring length L, for example, the calculation formulas (5) to (8) to command the high-frequency voltage. Is corrected, and the corrected high-frequency voltage command is output to the high-frequency voltage generator 7. The wiring length L may be input at regular intervals, and the same calculation formula can be used while the wiring length L does not change. Therefore, when the wiring length changes, the wiring length L is input. You may be broken. The wiring length L input in the correction mode is the wiring length during operation of the motor 1. As described above, the high-frequency voltage correction unit 8 of 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 during operation of the motor 1. The high frequency voltage command is corrected based on.

As described above, according to the second embodiment, the relationship between the wiring length and the adjustment amount that satisfies 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. Therefore, even when a voltage error occurs due to stray capacitance during long wiring, sensorless vector control of the high frequency superimposition method can be performed without lowering the magnetic pole position estimation accuracy. Further, even when the wiring information is changed due to the change in the configuration, the magnetic pole position estimation accuracy can be maintained with high accuracy.

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

1 motor, 2 motor controller, 3 voltage application unit, 4 current detection unit, 5 estimation unit, 6 control unit, 7 high frequency voltage generator, 8 high frequency voltage correction unit, 9 adder unit, 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 a motor by being connected to a motor having a salient polarity by wiring.
An estimation unit that estimates the magnetic pole position of the motor based on the motor current flowing through the motor, and
A command calculation unit that generates a first AC voltage command for driving the motor, and
A second AC voltage command having a frequency higher than the frequency of the first AC voltage command is sent to the wiring .
A high-frequency voltage command generator that is generated based on the wiring length or stray capacitance of the wiring.
An adder that generates a drive voltage command by superimposing the second AC voltage command on the first AC voltage command, and
A motor control device characterized by comprising. A motor control device that controls a motor by being connected to a motor having a salient polarity by wiring.
An estimation unit that estimates the magnetic pole position of the motor based on the motor current flowing through the motor, and
A command calculation unit that generates a first AC voltage command for driving the motor, and
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 based on the wiring information that is information about the wiring.
An adder that generates a drive voltage command by superimposing the second AC voltage command on the first AC voltage command, and
With
The high-frequency voltage command generation unit is characterized in that the second AC voltage command is generated from the relationship between the pre-measured high-frequency current having the same frequency as the second AC voltage command and the wiring information. Motor control device. A motor control device that controls a motor by being connected to a motor having a salient polarity by wiring.
An estimation unit that estimates the magnetic pole position of the motor based on the motor current flowing through the motor, and
A command calculation unit that generates a first AC voltage command for driving the motor, and
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 based on the wiring information that is information about the wiring.
An adder that generates a drive voltage command by superimposing the second AC voltage command on the first AC voltage command, and
With
The high-frequency voltage command generation unit generates the second AC voltage command from the relationship between the pre-measured adjustment amount for adjusting the second AC voltage command based on the wiring information and the wiring information. A motor control device characterized by the fact that. The motor control device according to claim 2 or 3, wherein the wiring information is the wiring length of the wiring or the stray capacitance of the wiring.

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