JP5479094B2 - Synchronous motor control method and control apparatus - Google Patents

Description

  The present invention relates to a synchronous motor control method and control apparatus using a permanent magnet as a field.

  A synchronous motor used for a servo motor generates a thrust by generating a field magnetic flux with a permanent magnet and passing a three-phase armature current so that the field magnetic flux and the composite vector are orthogonal to each other. A block diagram of the servo motor system is shown in FIG. A synchronous motor 31, a power converter 32 such as a voltage-type PWM inverter that supplies power to the synchronous motor 31, a voltage supplied to the synchronous motor 31 by the power converter 32, or a phase detector 33 for determining the phase of the flowing current; A current controller 34 for performing current control is a basic configuration. A speed detector 35 is added for speed control, and a position detector 36 is added for position control. The phase detector 33, the speed detector 35, and the position detector 36 are often shared.

  In the circuit equation of the synchronous motor, the easiest to handle is the voltage, current, etc., expressed in dq coordinates, which are direct current quantities. In the dq coordinate, the direction of the magnetic flux generated by the field is the d axis, and the phase advanced by π / 2 with respect to the d axis is the q axis. The thrust acting on the movable part is proportional to the current flowing through the q-axis armature. In the conventional servo motor using the phase detector 33, the q-axis armature current is controlled so as to obtain a necessary torque. Since the d-axis is the direction of the magnetic flux of the field, the d-axis armature current is normally controlled so as not to flow. The current controller 34 calculates the current magnetic pole position (d-axis position) from the phase detector 33, and flows current to the q-axis armature that is shifted by π / 2 from the magnetic pole position, so that the movable part is smooth. Control to work. When a servo motor is used, accurate positioning control can be performed, and since the magnitude of the current can be controlled according to the torque, there are advantages that the motor efficiency is good and the power consumption can be reduced.

  However, in order to perform feedback control using dq coordinates, an expensive position detector such as an encoder or a pulse generator (or a phase detector such as a magnetic sensor) is required. If the position of the magnetic pole (d-axis position) is not known, the three-phase AC / dq coordinate converter 37 cannot coordinate-convert the three-phase AC current into the d-axis and q-axis armature current, and d This is because the -q coordinate / 3-phase AC converter 38 cannot coordinate-convert the d-axis and q-axis armature currents into 3-phase AC currents.

  A position sensorless control circuit is known as a circuit for controlling the position of a synchronous motor without using a position detector (see, for example, Patent Document 1). In the position sensorless control, a motor current flowing in the motor is detected, the rotor position of the motor is estimated using the motor current, and a signal for rotating the motor at a rotation speed according to the command is given to the PWM inverter.

In addition, as a method for controlling the position of the motor without using a position detector, a pulse motor that performs open-loop control of the rotation angle of the motor based on the number of input pulses to the drive circuit is also known.
JP 2006-67656 A

  However, in the position sensorless control circuit, it is necessary to coordinate-transform the voltage equation on the real axis (dq coordinate axis) into the voltage equation on the control axis (δ-γ coordinate axis), and the control becomes complicated. There is a problem.

  In addition, although the pulse motor can realize accurate positioning, it requires a gear-shaped special rotor, and thus there is a problem that the motor itself becomes expensive or large.

  Therefore, an object of the present invention is to provide a new synchronous motor control apparatus and method that eliminates the need for a position detector and is easy to control.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a dq coordinate having a direction of magnetic flux generated by a field as a d-axis and a phase advanced by π / 2 with respect to the d-axis as a q-axis. In the synchronous motor control method used , a d-axis command, which is a magnetic pole position command of a permanent magnet to be driven, is calculated from a position command from the host, and a feedback current of the synchronous motor is calculated based on the d-axis command. into a current and q-axis armature current, constant current flows in the d-axis armature, and so no current flows in the q-axis armature, by controlling the d-axis armature current and the q-axis armature current The synchronous motor control method drives the synchronous motor by attracting the magnetic pole position of the permanent magnet to the magnetic pole position command and changing the position command from the higher order .

According to a second aspect of the present invention, there is provided a synchronous motor control apparatus using dq coordinates in which the direction of the magnetic flux generated by the field is d-axis and the phase advanced by π / 2 with respect to the d-axis is q-axis. , a phase generation means for calculating a d-axis command is pole position command of the permanent magnet to be driven from the position command from the host, a current detector for detecting a three-phase alternating current flowing through the synchronous motor, the phase generating means calculates Three-phase alternating current / dq coordinate conversion means for converting the three-phase alternating current detected by the current detector into a d-axis armature current and a q-axis armature current based on the d-axis command , d The d-axis armature current and the q-axis armature current are controlled so that a constant current flows through the shaft armature and no current flows through the q-axis armature, and the magnetic pole position of the permanent magnet is set to the magnetic pole position command. and a current control means for attracting the said from the host By varying the置指age, a control system for a synchronous motor for driving the synchronous motor.

According to a third aspect of the present invention, in the synchronous motor control device according to the second aspect of the present invention, a position detector that detects a position of the synchronous motor, a position command, and the synchronous motor detected by the detector. A position determination means for comparing the position and increasing the value of the current flowing through the d-axis armature or changing the electrical angle of the d-axis when the synchronous motor is not moving according to the position command; It is characterized by providing.

According the invention described in claim 4 is a synchronous motor controlled by the control method of the synchronous motor according to claim 1.

  According to the present invention, the electrical angle corresponding to the position command is generated, and the current is supplied to the d-axis armature and the current is not supplied to the q-axis armature. (D-axis position) can be attracted and stopped. And a synchronous motor can be driven by changing an electrical angle continuously.

Schematic showing a rotating field type synchronous motor that is an embodiment of the present invention BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the moving coil type synchronous linear motor which is an Example of this invention An equivalent circuit of a synchronous motor represented by dq coordinates according to an embodiment of the present invention The block diagram of the control apparatus using dq coordinate system of 1st embodiment of this invention. Operational diagram of a synchronous motor represented by dq coordinates according to an embodiment of the present invention ((a) in the figure shows an operation diagram of a conventional synchronous motor, and (b) in the figure shows an operation of the motor of this embodiment) (Show figure) The block diagram of the control apparatus of 2nd embodiment of this invention Block diagram of a conventional servo motor system

Explanation of symbols

11 ... Position controller 12 ... q-axis armature current controller (current control means)
13 ... d-axis armature current controller (current control means)
14: Phase detector (phase generating means)
DESCRIPTION OF SYMBOLS 15 ... Power converter 16 ... Vector rotator and 3 phase alternating current / dq coordinate converter 17 ... Current detector 19 ... Vector rotator and dq coordinate / 3 phase alternating current converter 20 ... Synchronous motor 21 ... Position detection 24: Position determination device (position determination means)

  Hereinafter, a synchronous motor control apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. As a synchronous motor to be controlled, a permanent magnet synchronous motor that uses a permanent magnet as a field magnet is used. As the permanent magnet synchronous motor, a rotating field type synchronous motor as shown in FIG. 1 may be used, or a moving coil type synchronous linear motor as shown in FIG. 2 may be used. In the rotating field type synchronous motor, by passing a three-phase alternating current through the armature winding 1, the permanent magnet 2 that creates the field rotates. In the moving coil type synchronous linear motor, N-pole and S-pole permanent magnets 4 are alternately arranged on the stator 3 side, and U, V, and W-phase coils 6 are wound on the mover 5 side. By passing a three-phase armature current through the coil 6, a moving field that moves linearly is generated, and the mover 5 moves linearly with respect to the stator 3.

  Whether a rotating field type synchronous motor in which a field rotates or a moving coil type synchronous linear motor in which a field moves linearly, the d and q axis armature currents are obtained using the dq coordinate system of rotating coordinates. Can be controlled. The dq conversion converts both the fixed part and the movable part of the synchronous motor into rotating orthogonal coordinates, and the coordinate system is the dq coordinate system. The q axis is in a phase advanced by π / 2 with respect to the d axis. In the case of a synchronous motor, the d-axis is generally taken in the direction of the magnetic flux generated by the field.

となる。この式の右辺第２項は、永久磁石の界磁によってｄ，ｑ軸電機子巻線に誘起する速度起電力ｅ_ｄａ，ｅ_ｑａを表しており、ｅ_ｄａ＝０，ｅ_ｑａ＝ω_ｒｅφ_ｆａである。図３は、電機子巻線がＤＣモータのように整流子に接続されて半径方向に無数にあり、それらに界磁と同じ速度で回転するｄ，ｑ軸上に配置されたブラシを通してｖ_ｄａ，ｖ_ｑａが印加され、ｉ_ｄａ，ｉ_ｑａが流れるということを示している。ｖ_ｄａ，ｖ_ｑａを直流電圧にすれば、ｉ_ｄａ，ｉ_ｑａも直流電圧になり、２軸直流で扱える。FIG. 3 is an equivalent circuit of a synchronous motor represented by dq coordinates. In FIG. 3, v _da and v _qa are d and q axis armature voltages, i _da and i _qa are d and q axis armature currents, φ _fa is the number of armature winding interlinkage magnetic fluxes, and R _a is an armature winding. line resistance, L _a is the self-inductance of the armature winding. From this equivalent circuit, a relational expression of voltage, current, impedance, that is, a circuit equation is obtained.

It becomes. The second term on the right side of this equation represents the speed electromotive forces e _da and e _qa induced in the d and q axis armature windings by the field of the permanent magnet, and e _da = 0 and e _qa = ω _re φ _fa . FIG. 3 shows that the armature windings are connected to a commutator like a DC motor and are innumerable in the radial direction, and v _da is passed through brushes arranged on the d and q axes rotating at the same speed as the field. , V _qa is applied and i _da , i _qa flows. If v _da and v _qa are set to DC voltages, i _da and i _qa also become DC voltages and can be handled by two-axis DC.

が得られる。When transforming Equation 1 into a state equation (differential equation),

Is obtained.

This equation means that d _da and q axis armature currents i _da and i _qa can be controlled by d _da and q axis armature voltages v _da and v _qa .

  FIG. 4 is a block diagram of a control apparatus using the dq coordinate system according to the first embodiment of the present invention. When driving the synchronous motor, the control device of this embodiment does not use a position detector, and always allows a constant current to flow through the d-axis (the direction of the magnetic flux of the permanent magnet) of the synchronous motor. To drive.

  The control device includes a position controller 11 that receives a position command, q-axis and d-axis armature current controllers 12 and 13 that are current control means for controlling q-axis and d-axis armature currents, and an electrical angle corresponding to the position command. The phase detector 14 is a phase generation means for generating a power converter 15 such as a voltage-type PWM inverter that supplies power to the synchronous motor in accordance with q-axis and d-axis armature voltage commands.

A position command θ ^* _rm is given to the position controller 11 from a host control device such as a computer. The position controller 11 outputs the position command θ ^* _rm to the phase detector 14. The phase detector 14 calculates the electric angle theta ^* _re corresponding to the position command, the vector rotator, 3-phase AC / d-q coordinate is a three-phase AC / d-q coordinate conversion unit the electrical angle theta ^* _re Output to the converter 16. The vector rotator / three-phase AC / dq coordinate converter 16 converts the three-phase feedback current values iu, iv, iw from the current detector 17 to the q-axis armature current i based on the electrical angle θ ^* _{re. qa} and d-axis armature current i _da are converted.

The q-axis armature current controller 12 calculates a difference between the q-axis armature current command and the q-axis armature current i _qa and calculates a command value v ^* _qa of the q-axis armature voltage. Here, the q-axis armature current command is set to zero. The q-axis armature current controller 12 controls the q-axis armature current i _qa so that the q-axis armature current i _qa becomes zero. In the conventional servo motor, the q-axis armature current command is variable according to the required torque. However, the present embodiment is characterized in that the q-axis armature current command is always set to 0. .

The d-axis armature current controller 13 calculates a deviation between the d-axis armature current command and the d-axis armature current i _da and calculates a command value v ^* _da of the d-axis armature voltage. Here, the d-axis armature current command is set to a constant current value, for example, a rated current of the synchronous motor. The rated current is a current value at which the synchronous motor does not burn even if a current is passed through the synchronous motor for a long time. In the conventional servo motor, the d-axis current command i ^* _da is normally set to 0, but this embodiment is characterized by being set to a constant current value.

The vector rotator / dq coordinate / 3-phase AC converter 19 is based on the voltage commands v ^* _da , v ^* _qa and the electrical angle θ ^* _re , so that the three-phase voltage commands v ^* _u , v ^* _v , Outputs v ^* _w . The power converter 15 performs PWM control on the output voltage based on these voltage commands, and controls the current flowing through the synchronous motor 20.

  FIG. 5 shows an operation diagram of the synchronous motor represented by dq coordinates according to the embodiment. FIG. 5A shows an operation diagram of the conventional feedback control using the position detector, and FIG. 5B shows an operation diagram of the open loop control of the present embodiment in which the position detector is not used. In conventional feedback control, the d-axis armature current is set to 0, and the q-axis armature current is controlled to a value that matches the required torque. Torque was generated by passing a current through the q-axis armature, and the permanent magnet 23 of the synchronous motor 20 was rotating ((a1) → (a2) → (a3)). The d-axis position (magnetic pole position) has been calculated from position information detected by the position detector.

  On the other hand, in the open loop control of this embodiment, first, the magnetic pole position command 22 (d-axis command) of the permanent magnet 23 to be driven is calculated from the position command. Then, the d-axis armature current and the q-axis armature current are controlled so that a constant current flows through the d-axis armature and no current flows through the q-axis armature. Then, the magnetic pole position (d-axis position) of the permanent magnet 23 is attracted to the magnetic pole position command 22 and stops at the position of the magnetic pole position command 22. If the magnetic pole position command 22 is changed in the order of (b1) → (b2) → (b3) in FIG. 5B, the permanent magnet 23 is rotated. When the motor stops, a holding force is generated when a rated current is passed through the synchronous motor 20.

  In the open loop control of the present embodiment, since no current is passed through the q-axis armature, the torque generated in the synchronous motor 20 is small. For this reason, when a load is applied to the synchronous motor 20, the synchronous motor 20 may not follow the change in the electrical angle. However, the torque of the synchronous motor 20 can be increased by passing the rated current through the synchronous motor 20. Further, as the electrical angle is gradually increased to +5 degrees, +10 degrees, +15 degrees, etc., the synchronous motor 20 gradually increases in torque (when the electrical angle is increased to +90 degrees, the largest torque is applied). The synchronous motor can be operated by increasing the electrical angle. Once the synchronous motor has operated, the synchronous motor continues to operate due to its inertia, so that it can finally approach the electrical angle.

  FIG. 6 shows a block diagram of a control device in the second embodiment of the present invention. In the control device of this embodiment, in order to operate the synchronous motor 20 with certainty, the control device of the first embodiment further includes a position detector 21 such as an encoder that detects the position of the synchronous motor 20, a synchronous motor. A position determiner 24 is added as position determining means for increasing the torque of the synchronous motor 20 when the motor 20 is not operating. Others: position controller 11, d-axis, q-axis armature current controllers 12, 13, vector rotator / three-phase AC / dq coordinate converter 16, vector rotator / dq-coordinate / 3-phase AC Since the configurations of the converter 19, the phase detector 14, and the power converter 15 are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted.

  In order to operate the synchronous motor 20 when the synchronous motor 20 is not operating, it is necessary to increase the current flowing through the synchronous motor 20 or to change the electrical angle of the synchronous motor 20. For example, a larger torque is generated when the electrical angle is +90 degrees than when the electrical angle is +5 degrees.

  The position determiner 24 compares the position command with the position of the synchronous motor 20 detected by the position detector 21. When the synchronous motor 20 is not operating in accordance with the position command, the d-axis armature current command is increased or the d-axis electrical angle is changed. When changing the electrical angle of the d axis, the phase detector 14 is operated to send a command to set the vector rotator to +90 degrees, for example. Since the torque of the synchronous motor 20 is increased by increasing the current flowing through the synchronous motor 20 or changing the electrical angle of the synchronous motor 20, the synchronous motor 20 can be operated.

  Once the synchronous motor 20 is operated, the synchronous motor 20 is rotated to a predetermined electrical angle by its inertia. If the operation of the synchronous motor 20 is confirmed, the position determiner may return the d-axis armature current to a constant current value or return the electrical angle to the original electrical angle corresponding to the position command.

  In addition, this invention is not restricted to the said embodiment, It can change into various embodiment in the range which does not change the summary of this invention. For example, the servo motor may be an analog servo system or a software servo system. In the case of a software servo system, the control device incorporates a microcomputer that performs control.

Claims (4)

In a synchronous motor control method using dq coordinates, in which the direction of the magnetic flux generated by the field is d-axis and the phase advanced by π / 2 with respect to the d-axis is q-axis,
Calculate a d-axis command that is a magnetic pole position command of a permanent magnet to be driven from a position command from the upper level,
Based on the d-axis command , the synchronous motor feedback current is converted into a d-axis armature current and a q-axis armature current,
By controlling the d-axis armature current and the q-axis armature current so that a constant current flows through the d-axis armature and no current flows through the q-axis armature, the magnetic pole position of the permanent magnet is changed to the magnetic pole position. Attracted to the directive,
A synchronous motor control method for driving the synchronous motor by changing the position command from the host . In a synchronous motor control apparatus using dq coordinates in which the direction of the magnetic flux generated by the field is d-axis and the phase advanced by π / 2 with respect to the d-axis is q-axis,
A phase generation means for calculating a d-axis command which is a magnetic pole position command of a permanent magnet driven from a position command from a higher level;
A current detector for detecting a three-phase alternating current flowing in the synchronous motor;
Based on the d-axis command calculated by the phase generation means, the three-phase AC / dq that converts the three-phase AC current detected by the current detector into a d-axis armature current and a q-axis armature current. Coordinate transformation means;
By controlling the d-axis armature current and the q-axis armature current so that a constant current flows through the d-axis armature and no current flows through the q-axis armature, the magnetic pole position of the permanent magnet is changed to the magnetic pole position. Current control means to attract to the command ,
A control device for a synchronous motor that drives the synchronous motor by changing the position command from the host . The synchronous motor control device further includes:
A position detector for detecting the position of the synchronous motor;
Whether the current value flowing in the d-axis armature is increased when the position command is compared with the position of the synchronous motor detected by the detector and the synchronous motor is not moving according to the position command. Or position determining means for changing the electrical angle of the d axis;
The control apparatus of the synchronous motor of Claim 2 characterized by the above-mentioned.   A synchronous motor controlled by the synchronous motor control method according to claim 1.

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