JP2013251978A - Permanent magnet synchronous motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet synchronous motor control device capable of preventing fine vibration of an electric motor shaft when a permanent magnet synchronous motor having salience is placed in a servo-lock operation under position-sensor-less control.SOLUTION: A permanent magnet synchronous motor control device includes a speed command comparator 3 which compares a speed command 23 with a predetermined command switching determination value 24, and further a d-axis current command switch 11 which selects one of a set stronger excitation command 37 and a generated d-axis current command 28 according to a comparison result of the speed command comparator 3, and outputs the selected stronger excitation command or d-axis current command as a d-axis current command 38 that a d-axis current deviation for finding a deviation by a d-axis current deviation computing element 12. When a target value 20 becomes a stop position command through a servo-lock operation and the speed command 23 becomes a 0-speed command, the d-axis current command switch 11 selects the stronger excitation command 37.

Description

  The present invention relates to a permanent magnet synchronous motor control device that drives a permanent magnet synchronous motor having saliency by position sensorless control.

  As a method of controlling a permanent magnet synchronous motor having saliency without a position sensor, there is a method of superimposing a position estimation signal on a voltage command, estimating a rotor position and a rotation speed from a motor current flowing at that time, and performing feedback control. It is known (see, for example, Patent Document 1).

International Publication No. 2009/040965

  However, the method of controlling a permanent magnet synchronous motor having saliency without a position sensor has the property that the estimation accuracy of the rotor position varies depending on the actual rotor position due to the electromagnetic characteristics of the permanent magnet synchronous motor. is there.

  For this reason, when the servo lock operation is performed while maintaining the rotational speed of the permanent magnet synchronous motor at 0 using the method of controlling without the position sensor, the command value calculated in the feedback loop vibrates due to variations in position estimation accuracy. As a result, the motor shaft may slightly vibrate.

  The present invention has been made in view of the above, and a permanent magnet synchronous motor control device capable of preventing fine vibrations of a motor shaft when a permanent magnet synchronous motor having saliency is servo-locked by position sensorless control. The purpose is to obtain.

  In order to solve the above-described problems and achieve the object, the present invention provides a position for calculating a speed command that is an operation amount for reducing a deviation between a target value and a rotor position estimated from a motor current of a permanent magnet synchronous motor. A controller, a speed controller for calculating a q-axis current command that is an operation amount for reducing a deviation between the speed command and the rotor speed estimated from the motor current, and detected from the q-axis current command and the motor current A q-axis current deviation calculator for calculating a deviation from the q-axis current, a q-axis current controller for calculating a q-axis voltage command which is an operation amount for reducing the deviation obtained by the q-axis current deviation calculator, A d-axis current deviation calculator for obtaining a deviation between a d-axis current command generated sometimes and a d-axis current detected from the motor current, and an operation amount d for reducing the deviation obtained by the d-axis current deviation calculator. Calculate shaft voltage command In a permanent magnet synchronous motor control device including a d-axis current controller, according to a comparison result of a speed command comparator that compares a predetermined command switching determination value with the speed command, and a comparison result of the speed command comparator, The d-axis current deviation calculator calculates a deviation of the selected strong excitation command or d-axis current command by selecting one of the set strong excitation command and the generated d-axis current command. A d-axis current command switching unit that outputs the shaft current command is further provided.

  According to the present invention, during the servo lock operation using the target value as the stop position command, the d-axis current command is strengthened and switched to the excitation command, and the magnetic field attracting the rotating magnetic field created by the rotor of the permanent magnet synchronous motor is generated by the motor current. As a result, the vibration of the feedback loop can be suppressed and the fine vibration of the motor shaft can be prevented.

FIG. 1 is a block diagram showing a main configuration of a permanent magnet synchronous motor control device according to an embodiment of the present invention.

  Embodiments of a permanent magnet synchronous motor control device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a block diagram showing a main configuration of a permanent magnet synchronous motor control device according to an embodiment of the present invention. In FIG. 1, in a control device for a permanent magnet synchronous motor (not shown) having a saliency, which is a servo motor, a slight vibration of the motor shaft that occurs when the permanent magnet synchronous motor is servo-locked by position sensorless control. The structure of the part to be prevented is shown extracted.

  The d-axis used for vector control of the permanent magnet synchronous motor is set in a direction parallel to the magnetic field created by the permanent magnet embedded in the rotor of the permanent magnet synchronous motor, and the q axis is set to the rotor of the permanent magnet synchronous motor. The direction is set perpendicular to the magnetic field created by the embedded permanent magnet.

  In FIG. 1, a position deviation calculator 1 receives a target value 20 (stop position command during servo lock operation) 20 from a host device, and a rotor estimated by a position estimator (not shown) from a motor current as a feedback signal to position control. A position (current position estimated value) 21 is input. The position deviation calculator 1 calculates a position deviation 22 between the target value (stop position command) 20 and the rotor position (current position estimated value) 21 and outputs it to the position controller 2.

  The position controller 2 is input from an operation amount that causes the rotor position 21 of the permanent magnet synchronous motor to follow the target value (stop position command at the time of servo lock operation) 20 given from the host device, that is, the position deviation calculator 1. A speed command 23 which is an operation amount for reducing the position deviation 22 is obtained by applying a proportional calculation (known P control) using a proportional gain to the position deviation 22. The speed command 23 obtained by the position controller 2 is output in parallel to the speed command comparator 3 and the speed deviation calculator 4.

  In addition to the speed command 23 from the position controller 2, the speed command comparator 3 receives a current / voltage command switching determination value 24 that gives a boundary between normal operation and servo lock operation from the host device. The speed command comparator 3 compares the speed command 23 with the current / voltage command switching determination value 24 and outputs a switching control signal 25 which is a binary level signal indicating the magnitude relationship between the two. The switching control signal 25 is input to each control port of the q-axis current command switching device 6, the q-axis voltage command switching device 9, and the d-axis current command switching device 11.

  In addition to the speed command 23 from the position controller 2, the speed deviation calculator 4 has a rotational speed (estimated rotational speed value) 26 of a motor estimated by a speed estimator (not shown) from a motor current as a feedback signal to the speed control. Entered. The speed deviation calculator 4 calculates a speed deviation 27 between the speed command 23 and the rotation speed (rotation speed estimated value) 26 of the electric motor, and outputs it to the speed controller 5.

  Here, the q-axis side contributing to the torque is constituted by a speed controller 5, a q-axis current command switch 6, a q-axis current deviation calculator 7, a q-axis current controller 8, and a q-axis voltage command switch 9. The

  The speed controller 5 is an operation amount for causing the rotational speed 26 of the permanent magnet synchronous motor to follow the speed command 23 obtained by the position controller 2, that is, an operation amount for reducing the speed deviation 27 input from the speed deviation calculator 4. Q-axis current command (here, referred to as “q-axis current normal command” because it is used during normal operation) 28 is obtained by applying proportional integral control (known PI control) to the speed deviation 27, and is obtained as q-axis current Output to one switching input terminal of the command switching device 6.

  The q-axis current command switching unit 6 receives a 0 command (herein referred to as “q-axis current 0 command” 29) used at the time of servo lock at the other switching input terminal, and the switching that the speed command comparator 3 outputs. According to the signal level of the control signal 25, either the q-axis current normal command 28 or the q-axis current 0 command 29 is selected, and this is used as the q-axis current command 30 from the switching base end to the q-axis current deviation calculator. 7 is output.

  The q-axis current deviation calculator 7 is a q-axis current detection value detected from the motor current by a current detector (not shown) as a feedback signal for torque control in addition to the q-axis current command 30 from the q-axis current command switch 6. 31 is input. The q-axis current deviation calculator 7 calculates a q-axis current deviation 32 between the q-axis current command 30 and the q-axis current detection value 31 and outputs it to the q-axis current controller 8.

  The q-axis current controller 8 is an operation for reducing the operation amount for causing the q-axis current detection value 31 of the permanent magnet synchronous motor to follow the q-axis current command 30, that is, the q-axis current deviation 32 from the q-axis current deviation calculator 7. A q-axis voltage command (here, referred to as “q-axis voltage normal command” because it is used during normal operation) 33 is obtained by applying proportional integral control (known PI control) to the q-axis current deviation 32, Output to one switching input terminal of the q-axis voltage command switching unit 9.

  The q-axis voltage command switching unit 9 receives a 0 command (herein referred to as “q-axis voltage 0 command” for distinction) 34 used at the time of servo lock at the other switching input terminal, and the switching that the speed command comparator 3 outputs. Depending on the signal level of the control signal 25, one of the q-axis voltage normal command 33 and the q-axis voltage 0 command 34 is selected and used as a q-axis voltage command 35 from the switching base end to a coordinate converter (not shown). Output.

  Next, the d-axis side configuration “d-axis current command generator 10, d-axis current command switching unit 11, d-axis current deviation calculator 12 and d-axis current controller 13” contributing to the excitation current will be described.

  The d-axis current command generator 10 generates a d-axis current command 36 (referred to herein as a “d-axis current normal command” for distinction) 36 that is used during normal operation by well-known PI control, and is used for servo locking. An excitation command 37 is also generated. The d-axis current normal command 36 and the strong excitation command 37 generated by the d-axis current command generator 10 are input to the corresponding switching input terminals of the d-axis current command switch 11.

  The d-axis current command switching unit 11 selects either the d-axis current normal command 36 or the strong excitation command 37 in accordance with the signal level of the switching control signal 25 output from the speed command comparator 3 and selects it. The d-axis current command 38 is output from the switching base end to the d-axis current deviation calculator 12.

  The d-axis current deviation calculator 12 detects the d-axis current detected from the motor current by a current detector (not shown) as a feedback signal for excitation current control in addition to the d-axis current command 38 from the d-axis current command switch 11. The value 39 is entered. The d-axis current deviation calculator 11 calculates a d-axis current deviation 40 between the d-axis current command 38 and the d-axis current detection value 39 and outputs it to the d-axis current controller 13.

  The d-axis current controller 13 is an operation amount for causing the d-axis current detection value 39 of the permanent magnet synchronous motor to follow the d-axis current command 38 output from the d-axis current command switch 11, that is, the d-axis current deviation calculator 11. A d-axis voltage command 41, which is an operation amount for reducing the d-axis current deviation 40 from the input, is obtained by applying proportional integral control (known PI control) to the d-axis current deviation 40, and this is obtained to a coordinate converter (not shown). Output.

  Next, the operation at the time of servo lock related to this embodiment will be described. When a permanent magnet synchronous motor having saliency is driven by position sensorless control, the estimation accuracy of the rotor position has a property of variation due to the electromagnetic characteristics of the permanent magnet synchronous motor.

  Therefore, there is no portion “speed command comparator 3, q-axis current command switching device 6, q-axis voltage command switching device 9 and d-axis current command switching device 11” added by this embodiment, and a d-axis current command generator. 10 generates only the d-axis current normal command 36 (and hence the d-axis current command 36), the target position 20 is set as the stop position command, and the rotation speed of the permanent magnet synchronous motor is maintained at 0 to perform the servo lock operation. , When the estimated accuracy of the current position estimated value 21 varies depending on the stop position, the speed command 23 calculated in the feedback loop vibrates, and accordingly, the q-axis current command 28, that is, the q-axis current command 30 vibrates. As a result, the motor shaft may slightly vibrate.

  Therefore, in this embodiment, in FIG. 1, when the target position 20 is a normal operation time command other than the stop position command by the servo lock operation, the switching control signal 25 indicating the comparison result of the speed command comparator 3 is shown. The signal level indicates “speed command 23”> “current / voltage command switching determination value”.

  In this case, the q-axis current command switching unit 6 selects the q-axis current normal command 28 and sets it as the q-axis current command 30, and the q-axis voltage command switching unit 9 selects the q-axis voltage normal command 33 and converts it to q The d-axis current command switch 11 selects the d-axis current normal command 36 and sets it as the d-axis current command 38. In this way, the conventional operation is performed during the normal operation other than the servo lock operation.

  On the other hand, when the target position 20 is set as a stop position command and the servo lock operation is performed while maintaining the rotation speed of the permanent magnet synchronous motor at 0, the signal of the switching control signal 25 indicating the comparison result of the speed command comparator 3 The level indicates “speed command 23” <“current / voltage command switching determination value”.

  In this case, first, the d-axis current command switching unit 11 selects the strong excitation command 37 and sets it as the d-axis current command 38. This also achieves the purpose of preventing slight vibration of the motor shaft, but in this embodiment. After that, the q-axis current command switching unit 6 selects the q-axis current 0 command 29 and sets it as the q-axis current command 30, and the q-axis voltage command switching unit 9 selects the q-axis voltage 0 command 34 and converts it to the q-axis. The voltage command 35 is assumed. By doing so, it is possible to more surely prevent fine vibration of the motor shaft.

  Specifically, the timing at which the q-axis current command switch 6 selects the q-axis current 0 command 29 and the q-axis voltage command switch 9 selects the q-axis voltage 0 command 34 is the same as the d-axis current command switch 11. Is the timing at which the speed command 23 becomes the almost zero speed command after the strong excitation command 37 is selected. That is, the switching control signal 25 output from the speed command comparator 3 is not a single control signal common to the q-axis current command switch 6, the q-axis voltage command switch 9 and the d-axis current command switch 11. The control signal is composed of two control signals, one for the q-axis current command switching unit 6 and the q-axis voltage command switching unit 9 and one for the d-axis current command switching unit 11.

  As described above, in this embodiment, during the servo lock operation in which the speed command 23 is almost zero, a strong excitation current is supplied in the d-axis direction of the permanent magnet synchronous motor, and the magnetic field generated by the motor current and the permanent magnet synchronous motor The rotor magnetic field created by the permanent magnet embedded in the rotor is attracted to each other.

  Here, in the permanent magnet synchronous motor control, generally, a stronger excitation current flows in the d-axis direction, a magnetic field generated by the motor current, and a rotor magnetic field generated by a permanent magnet embedded in the rotor of the permanent magnet synchronous motor. To attract each other is synonymous. In other words, a current that generates a magnetic field that attracts the rotor magnetic field is called a strengthening excitation current. The principle of attracting is the same as attracting magnets having different polarities (SN, NS). According to Fleming's right hand rule, the direction of the d-axis is determined so as to do so.

  When the rotor magnetic field is strengthened and attracted to the magnetic field generated by the excitation current, the rotor (and the motor shaft integrated with the rotor) is also attracted at the same time. Vibration can be suppressed more when there is an attractive force than when there is no attractive force. Therefore, it is possible to suppress the vibration of the motor shaft at the time of stopping due to the servo lock as compared with the case where there is no attracting torque due to the d-axis strong excitation current.

  In addition, when the servo lock is stopped, the estimated accuracy of the rotor position varies depending on the stop position, and even if the motor shaft vibrates, the q-axis current command switcher and the q-axis voltage command switcher have zero command. Is selected, and the amount of operation (speed command or q-axis current command) generated due to errors in position estimation or speed estimation is not transmitted to the motor, so that generation of vibration of the motor shaft can be reliably prevented. .

  As described above, the permanent magnet synchronous motor control device according to the present invention is capable of preventing fine vibration of the motor shaft when the servo lock operation of the permanent magnet synchronous motor having saliency is performed by position sensorless control. It is useful as an electric motor control device.

DESCRIPTION OF SYMBOLS 1 Position deviation calculator 2 Position controller 3 Speed command comparator 4 Speed deviation calculator 5 Speed controller 6 q-axis current command switching device 7 q-axis current deviation computing device 8 q-axis current controller 9 q-axis voltage command switching device 10 d-axis current command generator 11 d-axis current command switcher 12 d-axis current deviation calculator 13 d-axis current controller

Claims (5)

A position controller that calculates a speed command that is an operation amount for reducing a deviation between the target value and the rotor position estimated from the motor current of the permanent magnet synchronous motor;
A speed controller that calculates a q-axis current command that is an operation amount for reducing a deviation between the speed command and the rotor speed estimated from the motor current;
A q-axis current deviation calculator for obtaining a deviation between the q-axis current command and the q-axis current detected from the motor current;
A q-axis current controller for calculating a q-axis voltage command which is an operation amount for reducing the deviation obtained by the q-axis current deviation calculator;
A d-axis current deviation calculator for obtaining a deviation between the d-axis current command generated during operation and the d-axis current detected from the motor current;
A d-axis current controller for calculating a d-axis voltage command which is an operation amount for reducing the deviation obtained by the d-axis current deviation calculator;
In a permanent magnet synchronous motor control device comprising:
A speed command comparator for comparing a predetermined command switching determination value with the speed command;
According to the comparison result of the speed command comparator, one of the set strong excitation command and the generated d-axis current command is selected, and the selected strong excitation command or d-axis current command is selected as the d command. A permanent magnet synchronous motor control device, further comprising: a d-axis current command switching unit that outputs the d-axis current command as a d-axis current command for obtaining a deviation by a shaft current deviation calculator. According to the comparison result of the speed command comparator, one of the set 0 command and the q-axis current command output by the speed controller is selected, and the selected 0 command or q-axis current command is selected as the q command. A q-axis current command switching unit that outputs the q-axis current command as a q-axis current command by which a shaft current deviation calculator obtains a deviation;
According to the comparison result of the speed command comparator, either the set 0 command or the q-axis voltage command output from the q-axis current controller is selected, and the selected 0 command or q-axis voltage command is selected. The permanent magnet synchronous motor control device according to claim 1, further comprising: a q-axis voltage command switching unit configured to output the q-axis voltage command, which is an output of the q-axis current controller. When the target value is a stop position command by a servo lock operation and the comparison result of the speed command comparator, the command switching determination value is larger than the speed command
The permanent magnet synchronous motor control device according to claim 1, wherein the d-axis current command switching unit selects the strong excitation command. When the target value is a stop position command by a servo lock operation, and the comparison result of the speed command comparator, the command switching determination value is larger than the speed command,
The d-axis current command switching unit selects the strong excitation command,
The permanent magnet synchronous motor control device according to claim 2, wherein the q-axis current command switching unit and the q-axis voltage command switching unit select the corresponding 0 command.   The timing at which the q-axis current command switching unit and the q-axis voltage command switching unit select the 0 command is the same as that when the d-axis current command switching unit selects and outputs the strong excitation command, respectively. The permanent magnet synchronous motor control device according to claim 4, wherein the speed command is a timing at which the speed command becomes substantially zero.

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