JP5899842B2 - Electric motor position control device - Google Patents

Description

  The present invention relates to a position control device for an electric motor.

  FIG. 9 shows a block diagram of the position control device. A deviation signal between the position command θref and the motor position detection θdet is input to the position control unit 1 to generate a speed command ωref. The speed control unit 2 inputs the generated speed command ωref and the deviation signal of the speed detection ωdet calculated by the speed calculation unit 7 to generate a torque current command Tref, and the current control unit 3 based on the torque current command Tref. The motor 4 is controlled via A position detector (hereinafter referred to as an encoder) 5 detects the angular velocity at that time, converts it by an absolute angle conversion coefficient unit 6, and outputs it as a position detection θdet to the subtraction unit 8 and the velocity calculation unit 7.

  The position control shown in FIG. 9 has current control and speed control in a minor loop, and controls the position of the motor using the position control as a major loop. The position where the motor is at a certain point is 0 degree (from 0 to 360 degrees). The velocity command ωref is generated by position control from the deviation between the command θref and the position detection θdet (as an absolute angle less than).

  A device that performs position control as described above is known from Patent Document 1 and the like. This Patent Document 1 is provided with a vibration suppression compensator for suppressing the vibration of the mechanical system even when the parameters of the resonance / anti-resonance frequency of the mechanical system are unclear. It is described that a deviation from the signal is input to a vibration suppression compensator to generate a speed command compensation signal, and the sum of the compensation signal and the speed command basic signal is used as a speed signal.

JP 2003-325473 A

FIG. 10 shows the position control using the position control device as shown in FIG. 9 to execute the position control and the position detection with the difference of Z ^{−1 as} the difference. That is, 9, 10, and 11 are each provided with a delay circuit that delays one sampling period as the discrete time operator Z- ¹ . The subtraction unit 8 obtains a deviation signal Δθdet between the position command deviation signal Δθref and the position detection θdet delayed by one sampling period in the delay circuit 11, and further delays the deviation signal Δθdet by the delay circuit 10 by one sampling period. The deviation signals are added to obtain a position deviation θ and input to the position control unit 1.

  By the way, when the electric motor 4 which is a controlled object is a dynamometer, in a specimen such as an automobile, the position control mode is set to the forward / reverse mode, Methods such as an intra-circumferential deviation mode and a 180 degree discrimination mode are applied.

  FIG. 11 is an explanatory diagram of the forward / reverse rotation mode when the position detection θdet in FIG. 10 is sampled and one sample is 250 μsec. The current position A point of the mechanical system is the origin (zero reference point), and the origin Is 45 degrees, and in the case of the forward rotation mode, the position starts at the position of 45 degrees and operates only in the forward rotation direction as shown in FIGS. For this reason, when a reverse rotation direction command is received for each sample, a forward rotation is made in multiple rotations, and a data set signal is required for the command value, resulting in a rotation of up to 15 degrees.

  In the reverse rotation mode, as shown in FIGS. (C) and (d), only the reverse rotation direction is operated. Therefore, when a normal rotation direction command is received for each sample, multiple rotations are performed in reverse rotation. A data set signal is required for the value, and a change in one sample is a position control from 15 degrees to 45 degrees.

  FIG. 12 rotates to a position that does not cross the phase (0 degree position), and the angle is position control of 0 to less than 360 degrees.

  FIG. 13 is an explanatory diagram of a 180 degree discrimination mode. This method is a position control of deviation 0 to less than 360 degrees × n degrees from the current position within a range of 180 degrees per sample, and as shown in FIG. The change in the sample is a rotation position from 45 degrees to 315 degrees, and the change in one sample is the position control from 45 degrees to 135 degrees as shown in FIG.

Therefore, when the position control by the method as shown in FIG. 11 is executed by the position control device as shown in FIG. 10, the following problem occurs.
(1) In the position command based on the angle and the simple deviation calculation based on the delay of one sampling period for position detection, if the deviation calculation result, that is, a positive value to the position control unit 1 (command position> detected position before control) is positive If the direction is negative (command position <pre-control detection position), the motor is driven in the reverse direction to the command position. For this reason, it is not possible to drive to the command position by designating an arbitrary rotation direction.
(2) In particular, when a load (rotating body such as a specimen) is attached, such as when the controlled object is a dynamometer, position detection sets the unique point (origin) of the detector to 0 degrees. Although it is output, 0 degree on the load side and 0 degree of the dynamometer do not necessarily match due to the attachment of the position detector. For this reason, in the position command input based on the position coordinates on the load side, 0 degrees does not match (origin origin mismatch), and control to the intended position cannot be performed.
(3) When the resolution of the position command and the resolution of position detection are different, the value of the resolution difference always remains in the deviation calculation result. If the value of the resolution difference remains, the speed command of the position control output fluctuates, which may cause pulsation in speed and torque and may not be stable.

  An object of the present invention is to provide a position control device for an electric motor that solves the problems (1) to (3).

According to the first aspect of the present invention, the position command of the control object, the deviation signal Δθref of the position command delayed by one sample period from the position command, the position detection of the motor detected through the position detector, and the position detection The position deviation θ of the position detection deviation signal Δθdet delayed by one sample period is obtained, and a torque current command is generated by the deviation of the speed command ωref corresponding to the position deviation θ and the position speed detection ωdet corresponding to the position detection θdet. In the case of controlling the position of the controlled object via the current control unit by the torque current command,
A rotation direction designation command correction unit that inputs the deviation signal Δθref of the position command and the rotation direction setting and outputs a deviation signal Δθref corrected corresponding to the rotation direction is provided, and is corrected by the rotation direction designation command correction unit. It is characterized in that the position deviation θ between the deviation signal Δθref and the deviation signal Δθdet is obtained.

As described above, according to the present invention, the control object can be accurately controlled to any specified position even if the stop angle position of the control target is any position, even if the control object is rotated in the forward direction or the reverse direction. Thus, the disagreement between the position of the control object and the specimen can be resolved .

The block diagram of the position control apparatus which shows the Example of this invention. The flowchart of position command correction | amendment of the rotation direction designation | designated correction | amendment part of this invention. The block diagram of the position control apparatus which shows the other Example of this invention. The block diagram of the position control apparatus which shows the other Example of this invention. The coordinate conversion processing flowchart of the position coordinate system conversion part of this invention. The block diagram of the position control apparatus which shows the other Example of this invention. The block diagram of the position control apparatus which shows the other Example of this invention. The correction process flow figure of the resolution correction process part of this invention. The block diagram of the conventional position control apparatus. The block diagram of the conventional position control apparatus which made the difference the position command and position detection. Explanatory drawing of position control mode (forward / reverse mode). Explanatory drawing of a position control mode (one round deviation mode). Explanatory drawing of position control mode (180 degree | times mode).

  The present invention provides means for specifying a rotation direction and correcting a command in a position command system of a control object, thereby specifying an arbitrary rotation direction of the control object and driving the control object up to the command position. . In addition, by providing a position coordinate system conversion unit on the output side of the position detector, it is possible to resolve the origin mismatch between the controlled object and the specimen and to control the position from the outside of the position control system, as well as the resolution correction processing unit. By providing this, position control from outside the system of the position command can be performed. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. The same reference numerals are given to the same or corresponding parts as in FIGS.
Reference numeral 20 denotes a rotation direction designation command correction unit according to the present invention, which receives a position command θref and a position command deviation signal Δθref delayed by one sample period by the delay circuit 9.

  FIG. 2 is a flowchart for position command correction by the rotation direction designation command correction unit 20. When a rotation direction setting signal is input, it is determined whether forward rotation direction setting or reverse rotation direction setting in step S1, and the forward rotation direction is determined. In the case of setting, it is determined in step S2 whether Δθref ≧ 0 or Δθref <0. When Δθref ≧ 0, the deviation signal Δθref is output to the subtracting unit 8 as it is, but when Δθref <0, 360 degrees − | Δθref | is calculated in S3 to obtain the difference signal. The difference signal is output to the subtraction unit 8 as a corrected position command deviation signal Δθref.

  On the other hand, when it is determined in step S1 that the position command is the reverse direction setting, it is determined whether Δθref ≦ 0 or Δθref> 0 in step S4. When Δθref ≦ 0, the deviation signal Δθref is output to the subtracting unit 8 as it is, but when Δθref> 0, the calculation of Δθref-360 degrees is executed in step S5, and the deviation signal Δθref of the position command corrected for the deviation. To the subtracting unit 8.

  That is, the rotation direction designation command correction unit 20 refers to the rotation direction setting every time the position command input is confirmed, and outputs the position command deviation signal Δθref so as to stop at the set forward or reverse command position. It corrects and outputs to the subtraction part 8. The subtraction unit 8 performs a difference calculation between the input deviation signal Δθref and the position detection deviation signal Δθdet delayed by one sampling period by the delay circuit 11, and further integrates the difference signal by the delay circuit 10 (one sampling period). A delayed signal is added) to obtain a position deviation θ, which is input to the position control unit 1 to generate a speed command ωref.

The speed control unit 2 calculates the torque current command Tref by inputting the speed command ωref and the deviation signal of the speed detection ωdet calculated by the speed calculation unit 7, and passes the current control unit 3 based on the torque current command Tref. To control the motor 4. This
The current I output from the current control unit 3 is corrected (or not corrected) corresponding to the set rotation direction with reference to the rotation direction setting every time the position command input by the rotation direction designation command generation unit 20 is determined. Therefore, it is possible to stop at the rotational position set by the command.

  Therefore, according to this embodiment, when the rotation direction designation command correction unit 20 is provided and the electric motor as the control target is rotated to an arbitrary position, the rotation direction is input to the rotation direction designation command correction unit 20 together with the position command input. A signal to be specified is input, and the deviation signal Δθref is corrected according to the rotation direction. As a result, the above-described problem (1) can be solved, and the function can be improved when the motor is driven to the command position while specifying an arbitrary rotation direction.

FIG. 3 is a block diagram showing a second embodiment of the present invention, in which a rotation direction designation command correction unit 20a.
Is for correcting the deviation signal Δθref of the position command so as to drive in a direction in which the deviation between the previous rotation command and the current rotation command is within 180 degrees. For this purpose, the rotation direction designation command correction unit 20a outputs the deviation signal Δθref to the motor stopped at an arbitrary position A shown in FIG.
(A) 0 degree <| Δθref | <180 degrees ……… → Δθref is output.
(B) 180 degrees <| Δθref | <360 degrees ... → | Δθref | -360 degrees is output.
(C) When the position command θref is 180 degrees ....... → Drives in an arbitrary direction.
Others are the same as Example 1 shown in FIG.

  Therefore, according to the second embodiment, when the motor is rotated to an arbitrary position in the position control, the input command is divided so that the deviation from the previous position command is within 180 degrees in the arbitrary rotation direction. It is. As a result, the above-described problem (1) can be solved, and the function can be improved when the motor is driven to the command position while specifying an arbitrary rotation direction.

  FIG. 4 is a block diagram showing a third embodiment of the present invention. In this embodiment, a position coordinate system conversion unit 21 is provided in the position detection system so that position control can be performed in an arbitrary coordinate system. is there. That is, the angular velocity of the electric motor 4 is detected by the encoder 5, converted into the position detection θdet by the absolute angle conversion coefficient unit 6, and input to the position coordinate system conversion unit 21. The position coordinate system conversion unit 21 includes a storage unit, and stores a current position where the electric motor 4 (dynamometer) is stopped, and a coordinate system in which the stored position is set to 0 degrees is constructed.

  Here, “θ” indicates an absolute angle of 0 to less than 360 degrees in the coordinate system of the encoder 5 (coordinate system of the dynamo system), and “θ ′” is 0 in a coordinate system constructed by setting an arbitrary position as 0 degrees. An absolute angle of less than ~ 360 degrees is shown. The position coordinate system conversion unit 21 performs control itself in an arbitrary coordinate system by performing position coordinate system conversion on the output of the encoder 5 (output of the absolute angle conversion coefficient unit 6). As a result, the coordinate system used in the interface with the outside of the control system can use an absolute angle based on an arbitrary coordinate system. Therefore, the position command θ′ref input to the control system is a position command from outside the control system, and the others are the same as in FIG.

FIG. 5 shows a flow chart of position coordinate system conversion processing by the position coordinate system conversion unit 21.
When the position detection θdet is input to the position coordinate system conversion unit 21, the position detection θdet is compared with the storage position in step S11. As a result, when θdet ≧ stored position, in step S12, [θ′det = θdet−stored position] is calculated and converted into a new coordinate system position θ′det, and fed back to the position control system via the delay circuit 11. And input to the speed calculation unit 7.

On the other hand, when θdet <stored position in step S11, [θ′det = 360 degrees−stored position + θdet] is calculated in step S13 and converted to a new coordinate system position θ′det.

  According to the third embodiment, a position coordinate system conversion unit 21 that constructs a coordinate system in which an arbitrary position is set to zero degrees is provided, and the position detected by the encoder 5 is subjected to coordinate conversion, so that the position can be determined in an arbitrary coordinate system. Control is possible. As a result, the 0 degree mismatch (origin origin mismatch) on the load side and the dynamometer described in the above problem (2) can be eliminated, and the function improvement and the control performance improvement at the time of driving the dynamometer can be achieved. .

FIG. 6 is a block diagram showing a fourth embodiment of the present invention. In this embodiment, a position coordinate system conversion unit 21 is provided outside the feedback loop of the position control system, and the position coordinate system reverse conversion is performed on the input side of the position command. The portion 22 is provided, and the others are the same as those in FIG.
The position coordinate system inverse transform unit 22 receives an absolute angle position command θ′ref of 0 to less than 360 degrees in an arbitrary coordinate system that does not depend on the motor control system (dynamo system) input from outside the control system. .

  That is, the position coordinate system inverse transform unit 22 stores the position of the dynamometer in response to the occurrence of an event by a position storage signal or the like, and constructs a new coordinate system in which the stored position is 0 degree. After the construction of the new coordinate system, the input position command θ′ref is converted into the position command θref of the encoder coordinate system by the position coordinate system inverse conversion unit 22, and the position is controlled in the same manner as in FIG.

  On the other hand, the position coordinate system conversion unit 21 provided outside the feedback loop of the position control system receives the position detection θdet and converts it into the new coordinate system position θ′det according to the processing flow shown in FIG. The det is output to the external output interface 12 such as a monitor. Thereby, it is possible to control from the outside of the dynamometer using a coordinate system in which an arbitrary point is set to 0 degree.

  Therefore, according to the fourth embodiment, a new coordinate system in which an arbitrary position is set to 0 degrees is constructed, a position command input by the new coordinate system is converted into an encoder detection coordinate system, and an external output interface is used. The position detection by the encoder detection coordinate system is converted to the new coordinate system. As a result, the dynamometer can be regarded as performing position control at an arbitrary position of 0 degree, and the dynamometer described in (2) of the above-mentioned problem and the load side mismatch of 0 degrees (origin mismatch) ) Can be eliminated, and the function can be improved when the dynamometer is driven.

FIG. 7 is a block diagram showing a fifth embodiment of the present invention, in which a resolution correction processing unit 23 is provided on the input side of the control system. The other configuration is the same as in FIG.
“Θ” and “θ ′” shown in FIG. 7 are based on the resolution of each angle data, and “θ” indicates the mechanical angle data of the resolution (depending on the number of pulses, etc.) of the encoder 5, “Θ ′” indicates mechanical angle data of the resolution (depending on the data width of the interface with the outside of the control system) of the input control command.

  When the position command θ′ref is input from outside the control system, the resolution correction processing unit 23 converts the position correction value into a pulse converted value of the encoder 5 used for detection. Here, the equivalent pulse converted value of the encoder 5 is a value obtained by pulse-converting the encoder output value when the electric motor 4 is rotated forward from 0 to the command position. For example, when an incremental encoder having a gear of 256 teeth is used, a position command of 180 degrees is equivalent to 512 pp (256 teeth × 4 times × (180 degrees / 360 degrees)). For this encoder pulse conversion value, the resolution of the position command θref and position detection θdet is the same by obtaining the absolute angle again using the same coefficient as the absolute angle conversion coefficient from the encoder output value used in the detector to the absolute angle. Shall. FIG. 8 is a flowchart of the resolution correction processing unit 23.

  According to the fifth embodiment, when the position command and the position detection have different resolutions, the position command is converted into the equivalent of the encoder output value, and further converted back to the absolute angle using the same coefficient as the position detection. Thus, the difference between the position command and the position detection resolution is eliminated. Thereby, the pulsation of the speed command of the position control output generated when the resolution difference value described in the above-mentioned problem (3) remains is suppressed, and stable position control is possible.

DESCRIPTION OF SYMBOLS 1 ... Position control part 2 ... Speed control part 3 ... Current control part 4 ... Electric motor (dynamometer)
5. Position detector (encoder)
6 ... Absolute angle conversion coefficient 7 ... Speed calculation unit 20 ... Rotation direction designation command correction unit 21 ... Position coordinate system conversion unit 22 ... Position coordinate system inverse conversion unit 23 ... Resolution correction processing unit

Claims (1)

Position command to be controlled, deviation signal Δθref of position command delayed by one sample period from this position command, position detection of motor detected via position detector, and position detection delayed by one sample period from this position detection The position deviation θ with respect to the deviation signal Δθdet is obtained, a torque current command is generated by the deviation between the speed command ωref according to the position deviation θ and the position speed detection ωdet according to the position detection θdet, and the current control unit is For controlling the position of the controlled object via
A rotation direction designation command correction unit that inputs the deviation signal Δθref of the position command and the rotation direction setting and outputs a deviation signal Δθref corrected corresponding to the rotation direction is provided, and is corrected by the rotation direction designation command correction unit. Configured to obtain the positional deviation θ between the deviation signal Δθref and the deviation signal Δθdet ,
The rotation direction designation command correction unit outputs a correction signal at a position of 360 degrees − | Δθref | when the value of the deviation signal Δθref input when the rotation direction setting is the forward rotation direction is [Δθref <0], The deviation signal Δθref input when Δθref <0] is output, and the value of the deviation signal Δθref input when the rotation direction setting is the reverse rotation direction is [Δθref−360 degrees]. A position control device for an electric motor , characterized in that a position correction signal is outputted and a deviation signal Δθref inputted when [Δθref> 0] is outputted .

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