JP2006060897A - Controller for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for motors that detects the position of the rotor of a motor or a signal for rotation speed from a position detector or a speed detector in a low-speed range and estimates it in a high-speed range. <P>SOLUTION: The controller for motors includes: an estimator that estimates at least the rotation speed, of the rotor position and the rotation speed of a motor, from the current of the motor; a detector that detects at least the rotation speed, of the rotor position and the rotation speed of the motor; and a selector that selects the output of the estimator when the rotation speed of the output of the estimator or the detector is greater than a predetermined value and the output of the detector when it is smaller than the predetermined value, and produces output. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to the control of the rotational speed and torque of an electric motor, and proposes a method for performing high-accuracy and stable control over a wide range of speeds.

As an example, FIG. 2 shows a permanent magnet type synchronous motor without a position detector and a speed detector, and the prior art will be described based on this figure.
The power converter 2 supplies power to the permanent magnet type synchronous motor 1. The armature current i of the permanent magnet type synchronous motor 1 is subjected to rotational coordinate conversion in the current component converter 3 based on the position θ of the γ axis, which is the estimated position of the permanent magnet of the rotor of the permanent magnet type synchronous motor 1. Thus, the γ-axis component current iγ and the δ-axis component current iδ are output separately. Similarly, the input voltage v of the permanent magnet type synchronous motor 1 is subjected to rotational coordinate conversion in the voltage component converter 4 based on the estimated γ-axis position θ to be converted into a γ-axis component voltage vγ and a δ-axis component voltage vδ. Output separately.
The position error calculator 5 inputs iγ, iδ, vγ, vδ and the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 1,

Thus, the position error ΔθL obtained by subtracting the phase θ of the γ axis from the phase θR of the d axis, which is the position of the permanent magnet of the rotor of the permanent magnet type synchronous motor 1, is calculated and output. Here, R is the armature winding resistance of the permanent magnet type synchronous motor 1, Ld is the d axis inductance, Lq is the q axis inductance, and φ is the permanent magnet of the rotor of the permanent magnet type synchronous motor 1. P () means time differentiation within (). The high speed range position error calculator 6 inputs iγ, iδ, vγ, vδ and the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 1.

Thus, the position error ΔθH obtained by subtracting the phase θ of the γ axis from the phase θR of the d axis, which is the position of the permanent magnet of the rotor of the permanent magnet type synchronous motor 1, is calculated and output. For example, the switch 7 selects ΔθH when the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 1 is greater than a predetermined value, and selects ΔθL and outputs it as Δθ when it is smaller. The estimator 8 proportionally integrates and amplifies the position error ΔθH or ΔθL selected by the switch 7 and outputs it as the estimated rotational angular frequency ω of the rotor of the permanent magnet synchronous motor 1, and further estimates the rotational angular frequency. The estimated position of the permanent magnet of the rotor of the permanent magnet type synchronous motor 1, that is, the phase θ of the γ-axis is output by integrating ω over time. Although the detailed principle is omitted, since the position error Δθ can be brought close to 0 by the configuration of the estimator 8, the γ axis coincides with the d axis, and ω of the estimator 8 output is a permanent magnet type synchronization. This coincides with the rotational angular frequency ωR of the rotor of the electric motor 1. In order to prevent the denominator of equation (1) from becoming zero, it is necessary to prevent the value of p (iγ) from being zero. Therefore, the triangular wave-like high-frequency signal generated by the high-frequency generator 14 is added to the γ-axis current command iγ ** by the adder 13 via the switch 12 to obtain iγ *. Since the denominator of the equation (2) does not become 0 in the high speed range, 0 is selected by the switch 12 so that the high frequency signal is not superimposed on iγ *.
The torque converter 10 outputs a δ-axis current command iδ * for outputting the torque of the torque command T *, and the current controller 9 causes the iδ and iγ to follow the commands iδ * and iγ *. By outputting the control signal S to the power converter 2, torque control can be achieved. Further, speed control can be achieved by outputting a torque command in the speed controller 11 so that the estimated rotational angular frequency ω follows the speed command ω *. (For example, refer to Patent Document 1).
Japanese Patent No. 3509016

In the conventional technology as described above, a triangular wave-like high frequency signal is superimposed in a low speed region using the equation (1). This high frequency signal is useless because it is not related to speed control or torque control itself. Furthermore, the high frequency signal becomes a factor causing magnetic noise. Further, in a permanent magnet type synchronous motor having a surface magnet structure such as Ld = Lq, or a permanent magnet type synchronous motor having an embedded magnet structure in which Ld = Lq is obtained due to magnetic saturation depending on operating conditions, the denominator of the equation (1) is 0 Therefore, the position error cannot be calculated.
It is difficult to stably control the zero frequency region without using a speed detector in an induction motor as well as a permanent magnet type synchronous motor.
On the other hand, when a motor is controlled using a position detector or a speed detector, a position detector or speed detector with a large number of pulses is required to perform stable control at a low speed with high accuracy. When such a position detector or speed detector with a large number of pulses is used to drive an electric motor in a high speed range, the signals from the position detector and speed detector become high frequency, making detection difficult.

  In order to solve the above problems, to provide a motor control device that detects a position and rotation speed signal of a rotor of an electric motor from a position detector and a speed detector in a low speed range and estimates in a high speed range. is there.

  In order to solve the above-described problems, an estimator that estimates at least the rotation speed from the current of the motor among the position and rotation speed of the rotor of the motor, and among the position and rotation speed of the rotor of the motor. And at least a detector for detecting the rotational speed, and if the rotational speed of the estimator or the output of the detector is larger than a predetermined value, the output of the estimator is selected, and if the rotational speed is small, the output of the detector is selected. And a selector that outputs the motor, and using the output of the selector, the rotational speed or torque of the motor is caused to follow a command value.

  According to the present invention, in an electric motor, a position and speed signal can be obtained with high accuracy by a position detector and a speed detector in a low speed range, and in a high speed range where it is difficult to obtain a position and speed signal by a position detector and speed detector. It can be obtained by estimating the position and speed.

  The speed and torque of the motor could be controlled with high accuracy and stability in a wide range of speeds.

FIG. 1 is a block diagram of one embodiment of the present invention. 1 uses signals from the position detector and the speed detector in the low speed range, the position error calculator 5, the switch 7, the switch 12, the adder 13, and the high frequency generator 14 in FIG. A detector 15, a detector 16, a selector 17, and a position selector 18 are added, and only the added portion will be described.
The position detector 15 outputs a d-axis phase θR which is the position of the permanent magnet of the rotor of the permanent magnet type synchronous motor 1. The detector 16 outputs the rotational angular frequency ωR of the rotor of the permanent magnet synchronous motor 1. The selector 17 selects the detector 16 output ωR if the rotational angular frequency of the rotor of the permanent magnet synchronous motor 1 is smaller than a predetermined value, and selects the estimator 8 output ω if the rotational angular frequency is larger than the predetermined value. This is selected and output as the rotational angular frequency of the rotor of the permanent magnet type synchronous motor 1. Similarly, the position selector 18 selects the position detector 15 output θR if the rotational angular frequency of the rotor of the permanent magnet synchronous motor 1 is smaller than a predetermined value, and the estimator if the rotational angular frequency is larger than the predetermined value. 8 output θ is selected and output as the d-axis phase, which is the position of the permanent magnet of the rotor of the permanent magnet type synchronous motor 1.

Although not shown in FIG. 1, when the selector 17 switches the selection from the detector 16 output ωR to the estimator 8 output ω, the integral component in which the estimator 8 proportionally amplifies the position error is changed to ωR. By performing presetting, the selection switching operation of the selector 17 can be performed accurately and smoothly. Similarly, when the position selector 18 switches the selection from the position detector 15 output θR to the estimator 8 output θ, the integral value obtained by time-integrating the estimated rotational angular frequency ω is preset to θR. Thus, the selection switching operation of the position selector 18 can be performed accurately and smoothly.

  According to the present invention, the speed and torque of the electric motor can be controlled with high accuracy and stability in a wide range of speeds, so there is a great possibility of industrial use.

It is explanatory drawing which showed the Example of this invention. It is explanatory drawing which showed the prior art of the control apparatus of a permanent magnet type synchronous motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet type synchronous motor 2 Power converter 3 Current component converter 4 Voltage component converter 5 Position error calculator 6 High speed area position error calculator 7 Switch 8 Estimator 9 Current controller 10 Torque converter 11 Speed controller 12 Switch 13 Adder 14 High-frequency generator 15 Position detector 16 Detector 17 Selector 18 Position selector

Claims (1)

In the motor control device that causes the rotation speed or torque of the motor to follow the command value according to at least one of the position of the rotor of the motor and the rotation speed of the rotor,
An estimator that estimates at least the rotational speed from the current of the motor among the position and rotational speed of the rotor of the motor; and a detector that detects at least the rotational speed of the position and rotational speed of the rotor of the motor; A selector that selects the output of the estimator when the rotational speed of the output of the estimator or the detector is greater than a predetermined value, and selects and outputs the output of the detector when the rotational speed is smaller than the predetermined value. An electric motor control device that causes the rotational speed or torque of the electric motor to follow a command value using the output of the selector.

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