KR102561919B1 - Method and apparatus for compensating rotator position of AC motor - Google Patents

Abstract

A method and apparatus for correcting the position of a rotor of an AC motor are provided. A method for correcting the position of a rotor of an AC motor according to an embodiment of the present invention includes creating a position correction table for a full speed section based on a position correction value measured at at least two speeds of a rotor of an AC motor; Measuring the position and speed of the rotor; and correcting the position of the rotor by determining a position correction value corresponding to the measured speed of the rotor from the position correction table.

Description

Method and apparatus for compensating rotator position of AC motor

The present invention relates to an AC motor, and more particularly, to a method and apparatus for correcting the position of a rotor of an AC motor capable of correcting a position error of a rotor caused by a delay factor according to speed.

In general, an AC motor detects the position of a rotor and controls output based on this. At this time, the output of the position sensor attached to the rotor shaft of the AC motor may be different from the position information used in the controller.

Here, the component of the corresponding position is called an initial angle offset, and this component must be corrected after the position sensor and the inverter are connected. If the initial angle offset is wrong, the output performance of the AC motor is reduced by the torque component corresponding to the corresponding component.

In addition, even when the AC motor rotates at high speed even when the AC motor has an accurate initial angle offset in non-rotation, an error component may be generated due to a delay component of the sensor output or a delay component of preprocessing such as a low-pass filter, which adversely affects the output performance of the AC motor. can give

Accordingly, methods for correcting the initial angle offset have been suggested to improve the output performance of AC motors.

However, since such conventional initial angle offset correction corrects the initial angle offset component only at a specific speed, the delay component of the sensor and the delay component of the preprocessing according to the rotor speed are different at other speeds, resulting in a position error of the rotor. There is a problem in that the components cannot be accurately calibrated.

KR 2016-0046871 A

In order to solve the problems of the prior art as described above, an embodiment of the present invention is to provide a method and apparatus for correcting the position of a rotor of an AC motor capable of correcting a position error of a rotor due to a delay component of a sensor output. do.

According to one aspect of the present invention for solving the above problems, creating a position correction table for the full speed section based on the position correction value measured at at least two speeds of the rotor of the AC motor; measuring the position and speed of the rotor; and correcting the position of the rotor by determining a position correction value corresponding to the measured rotor speed from the position correction table.

In one embodiment, the preparing may include calculating a first position correction value at a first speed of the rotor; calculating a second position correction value at a second speed greater than the first speed; Calculating a position correction value in the full speed range of the rotor based on the calculated first position correction value and second position correction value; and converting and storing the calculated position correction values for each speed of the rotor into a table.

In one embodiment, the calculating of the position correction value may calculate the position correction value for the corresponding speed by linear interpolation with respect to the speed section between the first speed and the second speed.

In one embodiment, the step of calculating the position correction value is to calculate the position correction value for the corresponding speed by linear extrapolation with respect to a speed section that is smaller than the first speed and greater than the second speed. can

In one embodiment, the step of calculating the first position correction value and the step of calculating the second position correction value are performed in a state where the stator current of the AC motor is 0A (id = 0, iq = 0). The position correction value according to the position of the rotor at the time when the d-axis voltage is 0 (vd = 0) can be calculated as the position correction value of the corresponding speed.

According to another aspect of the present invention, a storage unit storing a position correction table prepared for a full speed section based on a position correction value measured at at least two speeds of a rotor of an AC motor; a pre-processing unit for pre-processing the position and speed of the rotor measured by the current sensing unit and the position/speed sensing unit; and a position correction unit configured to correct the position of the rotor by determining a position correction value corresponding to the measured rotor speed from the position correction table.

In one embodiment, the position correction value table calculates a first position correction value at a first speed of the rotor, calculates a second position correction value at a second speed greater than the first speed, and calculates the calculated A position correction value is calculated in the entire speed range of the rotor based on the first position correction value and the second position correction value, and the calculated position correction value for each speed of the rotor is tabulated and stored in the storage unit. It can be.

In one embodiment, a position correction value may be calculated for a speed section between the first speed and the second speed by linear interpolation.

In an embodiment, a position correction value may be calculated for a speed section that is smaller than the first speed and greater than the second speed by linear extrapolation.

In one embodiment, the position correction value according to the corresponding speed is at the time when the stator current of the AC motor is 0A (id = 0, iq = 0) and the d-axis voltage of the stator is 0 (vd = 0) It may be an initial angle offset according to the position of the rotor.

In one embodiment, the device for correcting the position of the rotor of the AC motor includes a position calculation unit for calculating the position of the rotor using the calculated position correction value; a control unit that determines a control value for controlling the output of the motor according to the calculated position of the rotor; and a motor output unit configured to change the control voltage of the motor according to the determined control value.

A method and apparatus for correcting the position of a rotor of an AC motor according to an embodiment of the present invention measure the position error components of the rotor in advance, create and store a position correction table, and use this when calculating the position of the rotor, thereby generating sensor output. Since the position error of the rotor due to the delay component of can be corrected, the output performance of the AC motor can be improved in a wide speed range.

In addition, the present invention can improve the control performance by correcting the position of the rotor in a simple manner while having excellent dynamic characteristics compared to the online method by measuring the position error component of the rotor according to the speed in an offline measurement method.

In addition, by compensating the delay component according to the speed, the torque error is not generated and the torque output characteristic and accuracy can be improved, and at the same time, the control stability at high speed can be improved by improving the weak flux control performance.

1 is a block diagram showing the main configuration of a hybrid vehicle including an AC motor rotor position correction device according to an embodiment of the present invention.
2 is a block diagram of an apparatus for adjusting the position of a rotor of an AC motor according to an embodiment of the present invention.
3 is a flowchart of a method for correcting the position of a rotor of an AC motor according to an embodiment of the present invention.
FIG. 4 is a detailed flowchart of a step of creating a position correction table in FIG. 3 .
5 is a graph showing that the voltage of the magnetic flux shaft is deformed when a positional error of the rotor occurs.
6 is a graph showing that the current of the magnetic flux shaft is deformed when a positional error of the rotor occurs.
7 is a graph showing an example of creating a position correction table in the method for adjusting the position of a rotor of an AC motor according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein. In order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

Hereinafter, an apparatus for adjusting the position of a rotor of an AC motor according to an embodiment of the present invention will be described in more detail with reference to the drawings. 1 is a block diagram showing the main configuration of a hybrid vehicle including a device for adjusting the position of a rotor of an AC motor according to an embodiment of the present invention, and FIG. 2 is a device for adjusting the position of a rotor of an AC motor according to an embodiment of the present invention. is a block diagram of

Referring to FIG. 1 , a hybrid vehicle 10 including an AC motor rotor position correction device according to an embodiment of the present invention includes an AC motor 11, a current sensor 12, a position/speed sensor ( 13) and an electronic control device 14.

Such a hybrid vehicle may be a BSG system in which an engine and a motor-generator are interlocked through a belt.

The AC motor 11 interlocks with the engine through a belt and can function as a start motor and a generator capable of generating AC voltage. For example, the AC motor 11 may be a three-phase synchronous motor.

The current sensing unit 12 is arranged in series between the AC motor 11 and the inverter to sense the current of the stator of the AC motor 11. The current sensing unit 12 may be a current sensor.

The position/speed sensor 13 is mounted on the rotor side of the AC motor 11 and detects the speed and position of the rotor. This position/velocity sensor 13 may be a Hall sensor, a resolver, or a rotary encoder.

The electronic control device 14 detects the driving state of the AC motor 11 by the current sensor 12 and the position/speed sensor 13 and controls the AC motor 11 based on this. For example, this electronic control unit 14 may be an ECU.

The electronic controller 14 may calculate and correct an initial angle offset that changes according to the speed of the rotor of the AC motor 11 from a position correction table.

Referring to FIG. 2 , the apparatus 100 for adjusting the position of a rotor of an AC motor according to an embodiment of the present invention includes a pre-processing unit 110, a position correcting unit 120, and a storage unit 130. The rotor position correction device 100 of such an AC motor may be implemented by an electronic control device 14 as shown in FIG. 1 .

The preprocessor 110 preprocesses the position and speed of the rotor of the AC motor 11 measured by the current sensor 12 and the position/speed sensor 13. Here, the preprocessing is to remove noise from the measured information. For example, the preprocessor 110 may be a low pass filter.

The position correction unit 120 determines the position of the rotor of the AC motor 11 by determining the position correction value from the position correction table stored in the storage unit 130 corresponding to the speed of the rotor preprocessed by the preprocessor 110 unit. Correct information.

That is, the position correction unit 120 may retrieve and determine a position correction value for correcting the initial angle offset according to the current rotor speed detected by the position/speed sensor 13 from a pre-manufactured position correction table. .

Here, the rotor position information (θ) used to control the AC motor 11 is divided into three components as shown in Equation 1 below.

Here, θ_position sensor is the output value of the position/velocity sensor 13, θ_offset static is the difference component between the output value of the position/velocity sensor 13 and the reference angle of the controller, and θ_offset variable is the angle variation component caused by the delay element. am.

At this time, θ_offset static is a fixed value and is determined according to the design of the AC motor 11, θ_position sensor is determined by the current speed of the rotor of the AC motor 11, and θ_offset variable is the position/speed sensor ( It is determined by the delay by the preprocessor 110 preprocessing the output value of 13) and the propagation delay of the position/velocity sensor 13 itself.

Therefore, the position error (θ_error) at a specific speed corresponds to the sum of θ_offset static and θ_offset variable. Here, θ_offset static is a fixed value, and θ_offset variable varies according to the speed of the rotor of the AC motor 11.

As a result, in order to calculate accurate position information of the rotor that controls the AC motor 11, correction of the θ_offset variable corresponding to the speed measured by the position/speed sensor 13 is required.

In the present invention, the angular variation component (θ_offset variable) caused by the delay element that varies by speed is prepared and stored as a position correction table in advance, and the position correction value is calculated by referring to it during actual control.

The storage unit 130 stores a position correction table having position correction values for each speed of the rotor of the AC motor 11 . Here, the position correction table is prepared for the entire speed section based on the position correction values measured at at least two speeds of the rotor of the AC motor 11.

The position correction value table calculates the first position correction value θcomp1 at the first speed w1 of the rotor of the AC motor 11, and calculates the first position correction value θcomp1 at the second speed w2 greater than the first speed w1. A second position correction value θcomp2 is calculated, and a position correction value is calculated in the full speed range of the rotor based on the calculated first position correction value θcomp1 and second position correction value θcomp2, and the calculated position correction value θcomp2 is calculated. This is a table of the position correction values for each speed of the rotor.

Here, the synchronous coordinate system voltage equation of the three-phase synchronous motor can be expressed as Equation 1 below.

Here, vd and vq are the d-axis and q-axis voltages of the stator on the synchronous coordinate system, respectively, id and iq are the d-axis and q-axis currents, respectively, Rs is the resistance, Ld and Lq are the d-axis and q-axis inductances, p is the derivative operator for time (d/dt), ωr is the speed of the rotor, and φf is the number of alternating magnetic fluxes.

At this time, assuming that the speed is not 0 and id and iq are 0, Equation 3 is shown below.

As can be seen from Equation 3, the exact position (θ) of the rotor can be determined by checking the voltage of the AC motor 11.

Therefore, the position correction value at the first speed (w1) and the second speed (w2) is when the d-axis voltage of the stator is 0 ( It may be an initial angle offset according to the position of the rotor at the time of vd = 0).

In this position correction table, the position correction value is calculated by linear interpolation in the speed section between the first speed w1 and the second speed w2, and is smaller than the first speed w1 or the second speed w2 For a larger speed range, the position correction value can be calculated by linear extrapolation.

The apparatus 100 for adjusting the position of a rotor of an AC motor may further include a position calculation unit 140, a control unit 150, and a motor output unit 160.

The position calculation unit 140 may calculate the position of the rotor of the AC motor 11 using the position correction value according to the current speed calculated by the position correction unit 120 .

The control unit 150 may determine a control value for output control of the AC motor 11 according to the position of the rotor calculated by the position calculation unit 140 and transmit it to the motor output unit 160 .

The motor output unit 160 may control the output of the AC motor 11 by changing the control voltage of the AC motor 11 according to the control value determined by the control unit 150 .

With this configuration, the apparatus 100 for correcting the position of the rotor of an AC motor according to an embodiment of the present invention can correct the position error of the rotor due to the delay component of the sensor output, and thus the output of the AC motor in a wide speed range. Performance can be improved, and control performance can be improved by correcting the position of the rotor in a simple way while having excellent dynamic characteristics compared to the online method. Control stability at high speed may be improved by improving speed control performance.

Hereinafter, a method for correcting the position of a rotor of an AC motor according to the present invention will be described with reference to FIGS. 3 to 7 .

Figure 3 is a flow chart of a method for correcting the position of a rotor of an AC motor according to an embodiment of the present invention, Figure 4 is a detailed flowchart of the step of creating a position correction table in Figure 3, Figure 5 is a position error of the rotor FIG. 6 is a graph showing that the current of the magnetic flux axis is deformed when a position error of the rotor occurs, and FIG. 7 is a method for correcting the position of a rotor of an AC motor according to an embodiment of the present invention. It is a graph showing an example of creating a position correction table in .

The method for correcting the position of a rotor of an AC motor (300) includes preparing a position correction table (S310), measuring the position and speed of the rotor (S320), and correcting the position according to the current speed (S330). include

More specifically, as shown in FIG. 3, first, a position correction table for the entire speed section is prepared based on the position correction values measured at at least two speeds of the rotor of the AC motor 11 (step S310).

The step of creating such a position correction table will be described in detail with reference to FIG. 4 .

As shown in FIG. 4 , first, the first position correction value θcomp1 may be calculated from the first speed w1 of the rotor of the AC motor 11 (step S311).

Here, the position error θ error due to the initial angle offset with respect to the rotor of the AC motor 11 causes the current and voltage of the vehicle speed shaft to be deformed, as shown in FIGS. 5 and 6, so that the output torque is deformed, Therefore, the output torque may be deformed and the stability of control may deteriorate.

As shown in FIG. 5, when there is no position error of the rotor of the AC motor 11 (a), only the d-axis voltage (vd) of the stator of the AC motor 11 appears, but the rotation of the AC motor 11 When the position error of the electrons occurs by θ error (b), the synchronous coordinate system of the AC motor 11 is transformed by θ error, so both the d-axis and q-axis voltages (vd, vq) of the stator of the AC motor 11 are deformed. .

That is, when there is no position error of the rotor of the AC motor 11 (see (a) in FIG. 5), the voltage equation of the stator of the AC motor 11 can be expressed as Equation 3 above.

However, when there is a position error (θerror) of the rotor of the AC motor 11 (see (b) in FIG. 5), the voltage equation of the stator of the AC motor 11 can be expressed as Equation 4 below .

In addition, as shown in FIG. 6, when there is no position error of the rotor of the AC motor 11 (a), the currents (id, iq) appear in phase with each axis, but the rotor of the AC motor 11 When the position error of is generated by θ error (b), it is deformed by θ error in the synchronous coordinate system of the AC motor 11, so that the current (id, iq) does not appear in phase with the d-axis and q-axis. At this time, the output torque is deformed due to a difference between the actual current and the magnitude component. That is, the current of the magnetic flux axis is deformed, and stability of control may be deteriorated.

That is, when there is no position error of the rotor of the AC motor 11 (see (a) in FIG. 5), the torque by the current of the stator of the AC motor 11 can be expressed as Equation 5 below.

However, when there is a position error (θerror) of the rotor of the AC motor 11 (see (b) in FIG. 5), the torque T due to the current of the stator of the AC motor 11 is expressed by Equation 6 below can be expressed as

Here, id' and iq' are currents of the d-axis and q-axis of the stator according to the position error (θerror) of the rotor of the AC motor 11, respectively.

Therefore, for control stability, the initial angle offset of the rotor of the AC motor 11 must be corrected.

In this case, the first position correction value θcomp1 may be calculated by measuring the initial angle offset according to the speed and position of the rotor.

For example, at the first speed (w1), in a state where the stator current of the AC motor 11 is 0A (id = 0, iq = 0), the d-axis voltage of the stator is 0 (vd = 0). An initial angular offset according to the position of the electron may be measured and calculated as a first position correction value θcomp1 for the first speed w1.

Next, the second position correction value θcomp2 may be calculated from the second speed w2 of the rotor of the AC motor 11 (step S312). Here, the second speed w2 may be greater than the first speed w1. In this case, the second position correction value θcomp2 may be calculated by measuring the initial angle offset according to the speed and position of the rotor.

For example, at the second speed w2, in a state where the stator current of the AC motor 11 is 0A (id = 0, iq = 0), the d-axis voltage of the stator is 0 (vd = 0). The initial angle offset according to the position of the electron may be measured and calculated as the second position correction value θcomp2 for the second velocity w2.

Next, a position correction value may be calculated in the full speed range of the rotor of the AC motor 11 based on the first position correction value θcomp1 and the second position correction value θcomp2 (step S313).

Here, since the initial angle offset with respect to the rotor of the AC motor 11 is proportional to the speed, the first position correction value θcomp1 and the second position correction value θcomp1 and It can be predicted that it changes linearly with respect to the two-position correction value θcomp2.

For example, as shown in FIG. 7, a position correction value for a corresponding speed can be calculated by linear interpolation with respect to a speed section between the first speed w1 and the second speed w2. .

That is, in the graph of FIG. 7 , a position correction value for a corresponding speed section may be calculated by a straight line connecting the first speed w1 and the second speed w2. Since the position correction value is linear within the entire speed range of the rotor, the first speed (w1) and the second speed (w2) are not limited to specific values, but are 1/3 or 2/3 the size of the entire speed range. It is desirable to calculate the position correction value in .

In addition, with respect to the speed section smaller than the first speed w1 and the speed section greater than the second speed w2, a position correction value for the corresponding speed may be calculated by linear extrapolation.

That is, in the graph of FIG. 7, the position correction for the speed sections below the first speed w1 and below the second speed w2 is performed by a straight line extending from the first speed w1 and the second speed w2, respectively. value can be calculated. Here, when the entire section is calculated by the two velocities w1 and w2, the straight line calculated by the linear interpolation method between the first and second velocities w1 and w2 is substantially extended for other sections. A position correction value can be calculated.

Meanwhile, in this embodiment, position correction values are calculated for two speeds, the first speed w1 and the second speed w2, and the position correction values for the entire speed section are calculated by interpolation and extrapolation using these values. However, it is not limited thereto, and it is possible to calculate position correction values at two or more speeds and use them to calculate position correction values for each speed section.

For example, when the position correction value is calculated at three speeds (w1, w2, w3), in the section between the first speed (w1) and the second speed (w2), the first position correction value (θcomp1) at each speed ) and the second position correction value θcomp2, the position correction value is calculated by a straight line, and in the section between the second speed w2 and the third speed w3, the second position correction value at each speed ( The position correction value may be calculated by a straight line connecting θcomp2) and the third position correction value θcomp3.

At this time, in the speed section smaller than the first speed w1, the position correction value is calculated by a straight line extending from the straight line of the first speed w1 and the second speed w2, which are adjacent sections, and the third speed w3 ), a position correction table can be created by calculating a position correction value by a straight line extending from the straight line of the second speed (w2) and third speed (w3) sections, which are adjacent sections.

In this way, if position correction values are calculated for two or more velocities and a position correction table is prepared based thereon, it is possible to calculate a position correction value that is closer to the actual one for the velocities.

Position correction values for each speed of the rotor of the AC motor 11 calculated for the entire speed range as shown in FIG. 7 may be tabled and stored in the storage unit 130 (step S314).

Referring back to FIG. 3 , the position and speed of the rotor of the AC motor 11 are measured (step S320). At this time, the position and speed of the rotor may be measured using the current sensor 12 and the position/speed sensor 13, and may be preprocessed by a low-pass filter.

Next, the position correction value corresponding to the measured rotor speed is determined from the position correction table stored in the storage unit 130 to correct the position of the rotor (step S330).

The output of the AC motor 11 can be stably controlled through the position calculation unit 140, the control unit 150, and the motor output unit 160 based on the exact position of the rotor of the AC motor 11 calculated as described above. .

Since the position error of the rotor due to the delay component of the sensor output can be corrected by this method, the output performance of the AC motor can be improved in a wide speed range, and the dynamic characteristics are excellent compared to the online method. Control performance can be improved by correcting the position, torque output characteristics and precision can be improved because no torque error is generated, and control stability at high speed can be improved by improving weak flux control performance.

The methods described above may be implemented by the device 100 for adjusting the position of a rotor of an AC motor as shown in FIG. 1, and in particular, may be implemented by a software program that performs these steps. In this case, such a program These may be stored in a computer readable recording medium or transmitted by a computer data signal combined with a carrier wave in a transmission medium or communication network.

At this time, the computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored, and includes, for example, ROM, RAM, CD-ROM, DVD-ROM, DVD-RAM, and magnetic tape. , a floppy disk, a hard disk, an optical data storage device, and the like.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments can be easily proposed by means of changes, deletions, additions, etc., but these will also fall within the scope of the present invention.

10: hybrid vehicle 11: AC motor
12: current sensing unit 13: position / speed sensing unit
14: electronic control device 100: rotor position correction device
110: pre-processing unit 120: position correction unit
130: storage unit 140: location calculation unit
150: control unit 160: motor output unit

Claims (11)

Creating a position correction table for all speed sections based on the position correction values measured at at least two speeds of the rotor of the AC motor;
measuring the position and speed of the rotor;
pre-processing the measured position and speed of the rotor using a low-pass filter; and
Correcting the position of the rotor by determining a position correction value corresponding to the speed of the preprocessed rotor from the position correction table;
The position correction value is
A value for correcting the delay generated in the step of measuring and preprocessing the position and speed of the rotor
Rotor Position Correction Method of AC Motor. According to claim 1,
The writing step is
calculating a first position correction value at the first speed of the rotor;
calculating a second position correction value at a second speed greater than the first speed;
Calculating a position correction value in the full speed range of the rotor based on the calculated first position correction value and second position correction value; and
Forming and storing the calculated position correction values for each speed of the rotor into a table;
Rotor position correction method of an AC motor comprising a. According to claim 2,
The step of calculating the position correction value is a rotor position correction method of an AC motor in which a position correction value for a corresponding speed is calculated by linear interpolation for a speed section between the first speed and the second speed. . According to claim 2,
The step of calculating the position correction value is a rotor of an AC motor for calculating a position correction value for a corresponding speed by linear extrapolation with respect to a speed section that is smaller than the first speed and larger than the second speed. positioning method. According to claim 2,
In the step of calculating the first position correction value and the step of calculating the second position correction value, the d-axis voltage of the stator is 0 in a state where the stator current of the AC motor is 0A (id = 0, iq = 0). A rotor position correction method of an AC motor that calculates the initial angle offset according to the position of the rotor at the time (vd = 0) as the position correction value of the corresponding speed. a storage unit storing a position correction table prepared for a full speed section based on position correction values measured at at least two speeds of a rotor of an AC motor;
a pre-processing unit for pre-processing the position and speed of the rotor measured by the current sensing unit and the position/speed sensing unit using a low-pass filter; and
And a position correction unit for correcting the position of the rotor by determining a position correction value corresponding to the speed of the preprocessed rotor from the position correction table,
The position correction value is
A value for correcting the delay generated in the process of measuring and preprocessing the position and speed of the rotor
Rotor position correction device of AC motor. According to claim 6,
The position correction table is
Calculating a first position correction value at the first speed of the rotor;
A second position correction value is calculated at a second speed greater than the first speed;
Calculating a position correction value in the full speed range of the rotor based on the calculated first position correction value and second position correction value;
The rotor position correction device of an AC motor in which the calculated position correction values for each speed of the rotor are tabulated and stored in the storage unit. According to claim 7,
A rotor position correction device for an AC motor in which a position correction value is calculated by linear interpolation in the speed section between the first speed and the second speed. According to claim 7,
A rotor position correction device for an AC motor in which a position correction value is calculated by linear extrapolation in a speed section smaller than the first speed and greater than the second speed. According to claim 7,
The position correction value according to the speed is at the position of the rotor at the time when the d-axis voltage of the stator is 0 (vd = 0) in a state where the stator current of the AC motor is 0A (id = 0, iq = 0) A device for correcting the rotor position of an AC motor, which is an initial angle offset according to the According to claim 6,
a position calculation unit calculating a position of the rotor using the determined position correction value;
a control unit that determines a control value for output control of the AC motor according to the calculated position of the rotor; and
a motor output unit for changing a control voltage of the AC motor according to the determined control value;
Rotor position correction device of an AC motor further comprising a.

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