JP2005229717A - Current sensorless-control method and device of synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensorless control method and device of a synchronous motor applicable to an inverter that does not use pulse-width modulation (PWM) control without the need for switching a current estimation method by using the pulse width, i.e. a drive speed of the synchronous motor. <P>SOLUTION: The current sensorless control method of the synchronous motor controls a voltage applied to the synchronous motor by estimating the state of a phase current of the synchronous motor by using only a position sensor without the need for installing a voltage sensor and a current sensor that detect a voltage and a current output to the synchronous motor from a control device, respectively. The current sensorless control method comprises a current estimation means constituted of a disturbance compensation observer that defines an error between the torque voltage applied to the synchronous motor and a torque voltage command as a disturbance. The current estimation means obtains a current estimation value on the basis of a voltage command, a position signal and an angular speed from the position sensor, inputs the current estimation value to a current control means, and generates the voltage command by using the current estimation value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention does not include a voltage sensor or a current sensor for detecting a voltage or current output from a motor drive device, usually called an inverter, and estimates a phase current state of the synchronous motor using only a speed sensor. The present invention relates to a current sensorless control method and apparatus for a synchronous motor that controls the voltage applied to the synchronous motor.

  A conventional current control device for a synchronous motor includes a first means for obtaining a q-axis current estimated value based on a detected value or set value of a DC voltage of an inverter, a DC current obtained by filtering the DC current, and an inverter power equation, and an inverter And a second means for obtaining an estimated value of the alternating current flowing in the synchronous motor by sampling the direct current based on the switching mode of the current, and obtaining a q-axis current estimated value based on the estimated value of the alternating current. Accordingly, the first or second means is switched, and the magnetic pole position is controlled using the q-axis current estimated value output from the switched means (see, for example, Patent Document 1).

  In FIG. 4, a rotation speed command generator 101 that gives a rotation speed command ωr * of the synchronous motor 105 to be controlled, and an AC voltage supplied to the synchronous motor are calculated and converted into a pulse width modulated wave signal (PWM signal). It includes a control device 102 for outputting, an inverter 103 driven by this PWM signal, a DC power supply 104 for supplying power to the inverter 103, and a current detector 106 for detecting the DC power supply I0 of the inverter. The inverter 103 includes a main circuit portion 131 of the inverter and a gate driver 132 that generates a gate signal to the main circuit. The DC power source 104 that supplies power to the inverter 103 includes a three-phase AC power source 141 and a three-phase AC power source. It is composed of a diode bridge 142 that rectifies current and a smoothing capacitor 143 that suppresses pulsating components included in the DC power supply. The control device 102 is configured as described below. That is, the rotational speed command ωr * output from the rotational speed command generator 101 is input to the conversion gain 107, where it is converted into the electrical angular frequency command ω1 * of the synchronous motor using the pole number P of the synchronous motor. The converted electrical angular frequency command ω1 * is input to the integrator 108, where the AC phase θdc inside the control device is calculated.

On the other hand, the direct current I 0 detected by the current detector 106 is input to the current reproducer 109. Based on the PWM signal generated by the PWM generator 118, the current reproducer 109 reproduces the alternating currents Iu, Iv, Iw flowing through the synchronous motor 105 by estimation. The reproduced current values of the three-phase alternating currents Iuc, Ivc, and Iwc are input to the dq coordinate converter 110, where they are converted into components on the dc-qc axis that is the rotation coordinate axis inside the control device. The converted q-axis current estimated value Iqc2 is input to the Iq * generator 114 via the switch 113. The Iq * generator 114 generates a q-axis current command value Iq * of the q-axis component (torque component) of the synchronous motor based on the input q-axis current estimated value Iqc2, and outputs it to the voltage command calculator 116. The Id * generator 115 generates a d-axis current command value Id * of the d-axis component of the synchronous motor and outputs it to the voltage command calculator 116.

Based on the input d-axis current command value Id *, q-axis current command value Iq *, and electrical angular frequency command ω1 *, the voltage command calculator 116 receives the d-axis voltage command value Vdc * and the q-axis voltage command value Vqc. * Is generated and output to the dq inverse converter 117. The dq inverse converter 117 converts the input voltage command values Vdc *, Vqc * on the dc-qc axis into AC voltage command values vu *, vv *, vw * on the three-phase AC axis to generate PWM. Output to the instrument 118. The PWM generator 118 generates a PWM signal for driving the inverter 103 based on the input AC voltage command values vu *, vv *, and vw * and outputs the PWM signal to the gate driver 132. The direct current I0 detected by the current detector 106 is also input to the filter 111, where the harmonic component contained in the direct current I0 is reduced. The direct current value I 0 ′ output from the filter 111 is input to the Iqc estimator 112.

The Iqc estimator 112 calculates a d-axis current estimated value Iqc1 that is a torque current component of the synchronous motor, and outputs it to the Iq * generator 114 via the switch 113. The switch 113 switches the output Iqc1 of the Iqc estimator 112 and the signal of the q-axis current component Iqc2 output from the dq coordinate converter 110, and inputs the signal to the Iq * generator 114 as the q-axis current estimated value Iqc.
The ω1 corrector 119 calculates a state quantity corresponding to an axial phase difference (axial phase difference) between the dq axis and the control axis dc-qc axis of the synchronous motor, and corrects the driving frequency command ω1 * of the synchronous motor. The amount Δω1 is obtained and output to the adder 120. The adder 120 adds Δω1 to the electrical angular frequency command ω1: output from the conversion gain 107, and outputs ω1c to the integrator 108. From the integrator 108, a phase command θdc obtained by integrating ω1c is output as phase information to the dq coordinate converter 110 and the dq inverse converter 117. The switching signal generator 121 generates a switching signal S1 to the switch 113 based on the rotational speed command ωr * output from the rotational speed command generator 101.

Thus, in the conventional synchronous motor driving device, the first means for obtaining the q-axis current estimated value based on the detected value or set value of the DC voltage of the inverter and the DC current obtained by filtering the DC current and the inverter power equation; A second means for obtaining an estimated value of an alternating current flowing in the synchronous motor by sampling a direct current based on the switching mode of the inverter and obtaining an estimated value of the q-axis current based on the estimated value of the alternating current; The procedure of switching the first or second means according to the speed and controlling the magnetic pole position using the q-axis current estimated value output from the switched means has been taken.
JP 2003-219678 A (page 14, FIG. 1)

  A conventional current control method for a current control device for a synchronous motor is divided into a case where the average pulse width of PWM pulses by pulse width modulation (PWM) control for driving the inverter is narrow and a case where the average pulse width is wide. Since the procedure for preparing current detection methods individually and using them separately is used, there is a problem that the current cannot be estimated correctly unless the pulse width is accurately switched. There is also a problem that it can be applied only to an inverter using pulse width modulation (PWM) control.

  The present invention has been made in view of such problems, and an inverter that does not use pulse width modulation (PWM) control without requiring switching of a current estimation method based on a pulse width, that is, a driving speed of a synchronous motor. However, it is an object of the present invention to provide a current sensorless control method and apparatus for a synchronous motor that can be applied.

In order to solve the above problem, the invention according to claim 1 is directed to speed control means for inputting a speed command and a speed feedback signal and outputting a current command to the current control means, and current control for outputting a voltage command based on the current command And a position detection means for detecting the position of the synchronous motor. The voltage output from the synchronous motor driving device to the synchronous motor, the voltage sensor for detecting the current, and the current sensor are not provided, and only the position sensor is used for synchronization. In a current sensorless control method for a synchronous motor that estimates a phase current state of the motor and controls an applied voltage to the synchronous motor, an error between the torque voltage applied to the synchronous motor and the torque voltage command is expressed as a disturbance with respect to the torque voltage command. Current estimation means configured by a disturbance compensation observer that performs voltage command, position signal from position sensor, angular velocity An estimated current value is obtained based on the signal, the estimated current value is input to the current control means, and a voltage command is generated using the estimated current value.
According to a second aspect of the present invention, a voltage command is generated by PI compensation for a deviation between the torque current command and the current estimated value by the current control means using the current estimated value.
According to a third aspect of the present invention, the current control means is processed by equation (1).
Here, iq is a q-axis current, dq is an error between the torque voltage value and the torque voltage command, ωe is an angular velocity, R is an armature winding resistance, ts is a sampling time, L is an inductance, J is an inertia , Kt is a torque constant, p is the number of pole pairs, Kaq # FF is a q-axis current loop gain in the current estimation means, and k1, k2, and k3 are observer gains.

According to a fourth aspect of the present invention, the estimated speed obtained by the current estimating means is a speed feedback signal or induced voltage compensation.
In addition, a speed control unit that inputs a speed command and a speed feedback signal and outputs a current command to the current control unit, a current control unit that outputs a voltage command based on the current command, and a position detection that detects the position of the synchronous motor Means for estimating the phase current state of the synchronous motor by using only the position sensor without using the voltage sensor for detecting the voltage output from the synchronous motor driving device to the synchronous motor, the current sensor, and the current sensor. In the current sensorless control method of the synchronous motor for controlling the applied voltage to the motor, step (20) of inputting the torque current command and the excitation current command, the deviation between the torque current command and the estimated torque current value, and the excitation current command and the excitation current command A step (21) for calculating a deviation from the current estimated value, and a proportional integral (PI) control to control the deviation between the torque current command and the torque current estimated value; Step (22) for calculating the excitation voltage command by proportional integration (PI) control of the deviation between the excitation voltage command and the excitation current command and the estimated excitation current value, and the synchronous motor with the torque voltage command and the excitation voltage command. It comprises a driving step (23), a step (24) for calculating an estimated torque current value by equation (1), and a step (25) for calculating an estimated excitation current value by equation (8). Current sensorless control method for a synchronous motor.
According to a fifth aspect of the present invention, a speed control unit that inputs a speed command and a speed feedback signal and outputs a current command to the current control unit, a current control unit that outputs a voltage command based on the current command, a synchronization A position detection means for detecting the position of the electric motor, and the voltage output from the synchronous motor driving device to the synchronous motor, the voltage sensor for detecting the current, and the current sensor are not provided, and the phase current of the synchronous motor is obtained using only the position sensor. In the current sensorless control device for a synchronous motor that estimates the state of the synchronous motor and controls the voltage applied to the synchronous motor,
A current estimation unit configured by a disturbance compensation observer that makes an error between the torque voltage applied to the synchronous motor and the torque voltage command a disturbance with respect to the torque voltage command; and the current estimation unit includes a voltage signal and a position signal from the position sensor. A current estimated value is obtained based on the angular velocity signal, the current estimated value is input to the current control means, and a voltage command is generated using the current estimated value.

  According to the first aspect of the present invention, it is not necessary to switch the current estimation method according to the pulse width, that is, the driving speed of the synchronous motor, and it can be applied to an inverter that does not use pulse width modulation (PWM) control. By making the voltage command in the case of controlling this model an actual voltage command, the vibration of the synchronous motor can be prevented. Further, according to the invention described in claim 2, it is not necessary to switch the current estimation method based on the pulse width, that is, the driving speed of the synchronous motor, and it can be applied to an inverter that does not use pulse width modulation (PWM) control. By making the voltage command for controlling the model of the synchronous motor an actual voltage command, vibration of the synchronous motor can be prevented.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of a current control device for a synchronous motor to which the method of the present invention is applied. In the figure, reference numeral 1 denotes a current control unit, which generates a voltage command (Vq # ff # ref) using the current estimation value (Iq # ff # fb) estimated by the current estimation unit 2. Reference numeral 2 denotes a current estimation unit, which is composed of the equation (1) generated from the model of the synchronous motor and the current speed equation. The current estimation unit 2 generates a current estimation value (Iq # ff # fb) using the voltage command (Vq # ff # ref) output from the current control unit 1 and the angular velocity signal ωe. Reference numeral 3 denotes a synchronous motor, which is driven by inputting a voltage command (Vq # ff # ref) of the current control unit 1 to a power converter (not shown).

Here, iq is a q-axis current, dq is an error between the torque voltage value and the torque voltage command, ωe is an angular velocity, R is an armature winding resistance, ts is a sampling time, L is an inductance, J is an inertia , Kt is a torque constant, p is the number of pole pairs, Kaq # FF is a q-axis current loop gain in the current estimation means, and k1, k2, and k3 are observer gains. The subscript ref represents the command value, and the hat symbol represents the estimated value.
When the synchronous motor 3 is driven according to the torque current command (Iq # ref), the current control unit 1 in FIG. 1 uses the torque current command (Iq # ref) and the current estimated value (Iq # ref) generated by the current estimation unit 2. The voltage command (Vq # ff # ref) is generated by PI compensation for the deviation from # ff # fb). The current estimation unit 2 generates a current estimation value (Iq # ff # fb) using the voltage command (Vq # ff # fb) generated by the current control unit 1 and the angular velocity signal generated from the encoder. The current estimator 2 is composed of equation (1) generated from the voltage / current equation and current velocity equation of the synchronous motor.
Next, the calculation method of the equation (1) constituting the current control unit 1 will be described.
Assuming that an error between the torque voltage value applied to the synchronous motor and the torque voltage command is a disturbance dq with respect to the torque voltage command, the voltage-current equation and the current-velocity equation of the synchronous motor are Equations (2).

Where Vd: excitation voltage, Iq: torque current, R: armature winding resistance, Lq: q-axis inductance, ωe: angular velocity, kt: torque constant, J: inertia, P: number of pole pairs, d / dt: It is a differential operator.
When the voltage-current equation and current-velocity equation of the synchronous motor are discretized, Equation (3) is obtained.

  Here, ts is the sampling time. When the Iq disturbance compensation observer current is calculated using this equation (3), equation (4) is obtained.

  Here, ωe (k) is an angular velocity signal from the encoder, and Vq is the voltage command Vq # ff # ref generated by the current control unit 1, the Iq disturbance compensation observer current becomes the current estimated value Iq # ff # fb. . Further, k3, k4, and k5 are observer gains, which are calculated by the equations (5), (6), and (7).

Where α is the pole of the disturbance compensation observer.
Further, the Id disturbance compensation observer current is calculated using the following equation (8).

Here, Ld: d-axis inductance.
When the deviation between the torque current command (Iq # ref) and the estimated current value (Iq # ff # fb) generated by the current estimation unit 2 is PI-compensated, equation (1) is obtained.
In this way, using the current estimation value generated by the current estimation unit configured using the disturbance compensation observer that configures the error between the torque voltage applied to the synchronous motor and the torque voltage command as a disturbance to the torque voltage command. The current control unit takes the procedure of generating a voltage command by PI compensation for the deviation between the torque current command and the estimated current value. Therefore, the synchronous motor can be operated without a current sensor using the voltage command in accordance with the torque current command. Can be driven. Also,

Can be used instead of the induced voltage compensation ωe × φ to perform the induced voltage compensation. The disturbance compensation observer estimated speed can also be used in place of a speed feedback signal for generating a torque command.

  FIG. 2 is a block diagram showing the configuration of a speed control apparatus for a synchronous motor to which the method of the present invention is applied. In the figure, 4 is a speed command. A speed control unit 5 generates a torque current command (Iq # ref) and an excitation current command (Id # ref) from the speed command 4 and the speed feedback signal 13. Reference numeral 7 denotes a position detection unit which detects a position from the encoder 8. Reference numeral 8 denotes an encoder. Reference numeral 9 denotes a two-phase / three-phase converter, which uses a position signal 12, an excitation voltage command (Vd # ff # ref) 18 and a torque current command (Vq # ff # ref) 19 to make Vu # ref, Vv # ref, Vw # ref is generated. Reference numeral 10 denotes a dead time compensator, which performs dq and two-phase three-phase conversion on the excitation current command (Id # ref) and the torque current command (Iq # ref) input to the current control unit 1, and this AC current. Compensation of dead time based on the polarity of A PWM control unit 11 generates a gate signal from the outputs Vu # out, Vv # out, and Vw # out of the dead time compensation unit 10 and applies Vu, Vv, and Vw to the synchronous motor 3 to It comes to drive. Reference numeral 12 denotes a position signal, which is an output of the position detector 7. Reference numeral 13 denotes a speed feedback signal, which is an output of the speed detector 6. Reference numeral 14 denotes an angular velocity signal (ωe), which is an output of the velocity detector 6. Reference numeral 15 denotes an encoder signal. Reference numeral 16 denotes an excitation current command (Id # ref). Reference numeral 17 denotes a torque current command (Iq # ref) which is an output of the speed control unit 5. 18 is an excitation voltage command (Vd # ff # ref). In the current control unit 1, the excitation current command and the equation (8)

Are generated by PI compensation. 19 is a torque voltage command (Vq # ff # ref), and the current control unit 1 determines the torque current command and the equation (1).

Are generated by PI compensation.

  In this way, using the current estimation value generated by the current estimation unit configured using the disturbance compensation observer that configures the error between the torque voltage applied to the synchronous motor and the torque voltage command as a disturbance to the torque voltage command. The current control unit takes the procedure of generating a voltage command by PI compensation for the deviation between the torque current command and the estimated current value. Therefore, the synchronous motor can be operated without a current sensor using the voltage command in accordance with the torque current command. Can be driven. Also,

Can be used instead of the induced voltage compensation ωe × φ to perform the induced voltage compensation. It can also be used instead of a speed feedback signal for generating a torque command.

FIG. 3 is a flowchart showing the processing procedure of the present invention for each step.
FIG. 3 shows a processing procedure of the current controller 1 and the current estimator 2 and is composed of steps 20 to 25.
In step 20, a torque current command and an excitation current command are input.
In step 21, a deviation between the torque current command (Iq # ref) and the estimated torque current value and a deviation between the excitation current command (Id # ref) and the estimated excitation current value are calculated.
In step 22, the torque current deviation is PI controlled to calculate the torque voltage command (Vq # ff # ref), and the excitation current deviation is PI controlled to calculate the excitation voltage command (Vd # ff # ref).
In step 23, the synchronous motor is driven by the torque voltage command (Vq # ff # ref) and the excitation voltage command (Vd # ff # ref) generated in step 22.
In step 24, the estimated torque current value of the (k + 1) th loop is calculated using the equation (1).
In step 25, the estimated excitation current value of the (k + 1) th loop is calculated using equation (8).
In this way, using the current estimation value generated by the current estimation unit configured using the disturbance compensation observer that configures the error between the torque voltage applied to the synchronous motor and the torque voltage command as a disturbance to the torque voltage command. The current control unit takes the procedure of generating a voltage command by PI compensation for the deviation between the torque current command and the estimated current value. Therefore, the synchronous motor can be operated without a current sensor using the voltage command in accordance with the torque current command. Can be driven.

  Using a current estimation value generated by a current estimation unit configured using a disturbance compensation observer that configures an error between the torque voltage applied to the synchronous motor and the torque voltage command as a disturbance to the torque voltage command, a current control unit Therefore, the voltage command is generated by PI compensation for the deviation between the torque current command and the estimated current value. Therefore, the synchronous motor is driven according to the torque current command without a current sensor using the voltage command. Can do. Also,

Can be used as an induced voltage compensation and speed feedback signal, and can be applied to a servo system.

The block diagram which shows the structure of the current control apparatus of the synchronous motor to which the method of this invention is applied. The block diagram which shows the structure of the speed control apparatus of the synchronous motor to which the method of this invention is applied. The flowchart which shows the process sequence of this invention The block diagram which shows the structure of the current control apparatus of the synchronous motor to which the conventional method is applied

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current control part 2 Current estimation part 3 Synchronous motor 4 Speed command 5 Speed control part 6 Speed detection part 7 Position detection part 8 Encoder 9 Two-phase / three-phase conversion part 10 Dead time compensation part 11 PWM control part 12 Position signal 13 Speed Feedback signal 14 Angular velocity signal (ωe)
15 Encoder signal 16 Excitation current command (Id_ref)
17 Torque current command (Iq_ref)
18 Excitation voltage command (Vd_ff_ref)
19 Torque voltage command (Vq_ff_ref)
20 Step 21 of inputting torque current command and excitation current command 21 Step of calculating deviation of torque current command (Iq # ref) and estimated torque current value and difference of excitation current command (Id # ref) and estimated current value of step 22 Torque Step 23 to generate voltage command (Vq # ff # ref) and excitation voltage command (Vd # ff # ref) Synchronous motor is set with torque voltage command (Vq # ff # ref) and excitation voltage command (Vd # ff # ref) Step 24 for driving Step 25 for generating estimated torque current value for k + 1 loop Step 25 for generating estimated current value for exciting current for k + 1 loop 101 Speed command (ωr *) generator 102 Controller 103 Inverter 104 DC power supply 105 Synchronous motor 106 Current Detector 107 Conversion Gain 108 Integrator 109 Current Reproducer 110 dq Coordinate Converter 111 Filter 112 Iqc Estimator 113 Switch 114 Iq * generator 115 Id * generator 116 Voltage command calculator 117 dq inverse converter 118 PWM generator 119 ω1 corrector 120 Adder 121 Switching signal generator 131 Main circuit portion 132 of inverter Gate driver 141 Three-phase AC power supply 142 Diode Bridge 143 Smoothing Capacitor

Claims (6)

Speed control means for inputting a speed command and a speed feedback signal and outputting a current command to the current control means, current control means for outputting a voltage command based on the current command, position detection means for detecting the position of the synchronous motor, The voltage output from the synchronous motor drive device to the synchronous motor, the voltage sensor for detecting the current, and the current sensor are not provided, and the phase current state of the synchronous motor is estimated by using only the position sensor. In a current sensorless control method of a synchronous motor for controlling an applied voltage,
Current estimation means comprising a disturbance compensation observer that makes an error between the torque voltage applied to the synchronous motor and the torque voltage command a disturbance to the torque voltage command;
The current estimating means obtains an estimated current value based on a voltage command and a position signal from the position sensor, an angular velocity signal,
A current sensorless control method for a synchronous motor, wherein the estimated current value is input to the current control means and a voltage command is generated using the estimated current value. 2. The current sensorless control method for a synchronous motor according to claim 1, wherein a voltage command is generated by PI compensation of a deviation between a torque current command and the current estimated value by the current control unit using the current estimated value. The current sensorless control method for a synchronous motor according to claim 1 or 2, wherein the current control means is represented by equation (1).
Here, iq is a q-axis current, dq is an error between the torque voltage value and the torque voltage command, ωe is an angular velocity, R is an armature winding resistance, ts is a sampling time, L is an inductance, J is an inertia , Kt is a torque constant, p is the number of pole pairs, Kaq # FF is a q-axis current loop gain in the current estimation means, and k1, k2, and k3 are observer gains.

4. A current sensorless control method for a synchronous motor according to claim 1, wherein the estimated speed obtained by said current estimating means is a speed feedback signal or induced voltage compensation. Speed control means for inputting a speed command and a speed feedback signal and outputting a current command to the current control means, current control means for outputting a voltage command based on the current command, position detection means for detecting the position of the synchronous motor, The voltage output from the synchronous motor drive device to the synchronous motor, the voltage sensor for detecting the current, and the current sensor are not provided, and the phase current state of the synchronous motor is estimated by using only the position sensor. In a current sensorless control method of a synchronous motor for controlling an applied voltage,
A step (20) of inputting a torque current command and an excitation current command;
Calculating a deviation between the torque current command and the estimated torque current value, and a deviation between the excitation current command and the estimated excitation current value (21);
Step of calculating an excitation voltage command by proportional-integral (PI) control of the deviation between the torque current command and the estimated torque current value and proportional-integral (PI) control of a difference between the torque voltage command and the excitation current command and the estimated excitation current value (22)
Driving the synchronous motor with the torque voltage command and the excitation voltage command (23);
A step (24) of calculating an estimated torque current value by equation (2);
Here, armature winding resistance R, inductance Lq, sampling time ts, torque constant Kt, number of pole pairs P, inertia J, observer gains k1, k2, k3, actual speed and estimated speed

Estimated excitation current value is calculated using equation

Here, Ld: a current sensorless control method for a synchronous motor comprising the step (25) of calculating with d-axis inductance. Speed control means for inputting a speed command and a speed feedback signal and outputting a current command to the current control means, current control means for outputting a voltage command based on the current command, position detection means for detecting the position of the synchronous motor, The voltage output from the synchronous motor drive device to the synchronous motor, the voltage sensor for detecting the current, and the current sensor are not provided, and the phase current state of the synchronous motor is estimated by using only the position sensor. In the current sensorless control device of the synchronous motor that controls the applied voltage,
A current estimation unit configured by a disturbance compensation observer that makes an error between the torque voltage applied to the synchronous motor and the torque voltage command a disturbance with respect to the torque voltage command; and the current estimation unit includes a voltage signal and a position signal from the position sensor. A current sensorless control device for a synchronous motor, wherein an estimated current value is obtained based on an angular velocity signal, the estimated current value is input to the current control means, and a voltage command is generated using the estimated current value.

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