JP2012220476A - Position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a position detector which is capable of performing more accurate position detection even if a two-phase sinusoidal signal is distorted.SOLUTION: A position detector comprises an analog signal generation section, an A/D converter, a phase correction value arithmetic section 8, a signal correction section and an angle arithmetic section. The analog signal generation section generates phase analog signals of multiple two-phase sinusoidal waves having orthogonality in proportion to a rotation speed of a motor. The A/D converter converts each instantaneous value obtained by sampling the phase analog signals at equal intervals into phase digital signals. The phase correction value arithmetic section 8 arithmetically operates a phase correction value for each phase digital signal. The signal correction section corrects a phase difference of the phase digital signals to 90° on the basis of the phase correction value and outputs the signals. The angle arithmetic section arithmetically operates a motor angle that is positional information of the motor 1, on the basis of the phase output signals from the signal correction section. The phase correction value arithmetic section 8 includes sinusoidal wave fitting means 11 which fits each phase digital signal to a sinusoidal waveform and outputs the signal, and phase difference arithmetic means 12 which arithmetically operates and outputs the phase correction value on the basis of each phase output from the sinusoidal wave fitting means 11.

Description

  The present invention relates to a position detector that detects the position of a drive shaft of a mechanical device.

  A position detector used to drive and control various mechanical devices is attached to a motor that drives the mechanical device. The position of the mechanical device is controlled by feeding back the position detected by the position detector. Be controlled.

  As such a position detector, it is common to generate an analog signal of a two-phase sine wave having a frequency orthogonal to the rotational speed of the motor and detect the position based on the two-phase sine wave signal. It is. In order to ensure position detection accuracy, it is ideal that the amplitudes of the two-phase sine wave signals are equal, the phase difference is accurately maintained at 90 degrees, and the DC offset voltage is zero. In practice, it is difficult to drive the offset voltage, amplitude, and phase difference of a two-phase sine wave that is an analog signal into an ideal signal. For this reason, after converting a two-phase sine wave analog signal into a digital signal, offset voltage correction and amplitude correction are performed, the phase difference is corrected to 90 degrees (for example, Patent Document 1), and position detection processing is performed. Yes.

JP-A-2-251720

  In the above prior art, a Lissajous waveform for one cycle of a two-phase sine wave signal is obtained, and an arc tangent of (short axis radius) / (major axis radius) of the elliptical figure that is the Lissajous waveform is calculated, thereby obtaining a phase difference. Is calculated. However, for example, when a harmonic component is included in the two-phase sine wave signal, an error occurs in the short axis radius or the long axis radius, and a value different from the phase difference to be obtained may be calculated. There was a problem that accurate position detection could not be performed.

  The present invention has been made in view of the above, and an object of the present invention is to provide a position detector that can perform more accurate position detection even when distortion occurs in a two-phase sine wave signal. .

  In order to solve the above-described problems and achieve the object, a position detector according to the present invention is a position detector that detects the position of a motor, and is a plurality of sensors that are proportional to the rotational speed of the motor and have orthogonality. An analog signal generation unit that generates each phase analog signal of a two-phase sine wave, an AD converter that converts each instantaneous value obtained by sampling each phase analog signal to each phase digital signal, and each phase digital signal A phase correction value calculation unit that calculates a phase correction value of the signal, a signal correction unit that corrects and outputs the phase difference of each phase digital signal to 90 degrees based on the phase correction value, and each of the signal correction units An angle calculation unit that calculates a motor angle that is position information of the motor based on the phase output signal, and the phase correction value calculation unit fits each phase digital signal into a sine waveform and outputs it. And waves fitting means, based on the phase output of the sine wave fitting means, characterized in that it comprises a phase difference calculating means for calculating and outputting the phase correction value.

  According to the present invention, even when distortion occurs in the two-phase sine wave signal, there is an effect that more accurate position detection can be performed.

FIG. 1 is a diagram illustrating a configuration example of a position detector according to an embodiment. FIG. 2 is a diagram illustrating an example of a block configuration of a position correction value calculation unit of the position detector according to the embodiment.

  A position detector according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment.
FIG. 1 is a diagram illustrating a configuration example of a position detector according to an embodiment. As shown in FIG. 1, the position detector 3 according to the embodiment detects a motor angle corresponding to the rotation of a motor 1 that drives a mechanical device (not shown) as motor position information, and controls driving of the motor 1. Output to servo amplifier 2.

  The position detector 3 according to the embodiment includes an analog signal generation unit 4, an AD converter 5, a signal correction unit 6, an angle calculation unit 7, and a phase correction value calculation unit 8.

  The analog signal generator 4 outputs a two-phase sine wave analog signal composed of two A-phase and B-phase sine wave signals having a frequency proportional to the rotational speed of the motor 1. The B-phase sine wave signal is a signal that is approximately 90 degrees out of phase with the A-phase sine wave signal. The phases of the A-phase sine wave signal and the B-phase sine wave signal advance depending on the rotation direction of the motor 1, and the delays are switched. The two-phase sine wave analog signal may be, for example, a fundamental two-phase sine wave signal in which the rotation period of the motor 1 is one period, or a 16th harmonic wave or 256 of the rotation period of the motor 1. It may be a two-phase sine wave signal of a double wave such as a double wave. Further, a configuration in which a plurality of these two-phase sine wave signals are generated may be used. Moreover, the structure which outputs the Z phase signal which shows the specific position used as the reference | standard of the rotation angle of the motor 1 other than A phase sine wave signal and B phase sine wave signal may be sufficient.

  The AD converter 5 converts each instantaneous value obtained by sampling a plurality of analog signals for one cycle of the two-phase sine wave generated by the analog signal generation unit 4 at equal intervals into a digital signal.

  The signal correction unit 6 corrects the offset voltage, amplitude, and phase difference of the two-phase sine wave signal converted into a digital signal by the AD converter 5. The phase difference correction value (phase correction value) is output from a phase correction value calculation unit 8 described later. This phase correction value, offset voltage correction value (offset voltage correction value), and amplitude correction are output. The present invention is not limited by the method of calculating the value (amplitude correction value).

  The angle calculation unit 7 calculates a motor angle, which is position information of the motor 1, based on the two-phase sine wave signal in which the above-described parameters are corrected by the signal correction unit 6, and outputs the motor angle to the servo amplifier 2. The present invention is not limited by the method of calculating the motor angle.

  The phase correction value calculator 8 calculates a phase correction value based on the two-phase sine wave signal converted into a digital signal by the AD converter 5 and the angle data calculated by the angle calculator 7.

  FIG. 2 is a diagram illustrating an example of a block configuration of a phase correction value calculation unit according to the embodiment. As shown in FIG. 2, the phase correction value calculation unit 8 includes a sine wave fitting unit 11, a phase difference calculation unit 12, and a phase correction value update determination unit 13.

  Next, the operation of the phase correction value calculation unit 8 according to the embodiment will be described with reference to FIG. 1 and FIG.

  The sine wave fitting means 11 fits each instantaneous value in one cycle of the two-phase sine wave signal converted into a digital signal by the AD converter 5 into an ideal sine waveform.

  Here, for example, when the analog signal generation unit 4 generates a plurality of two-phase sine wave signals, the other two-phase sine wave signals handled by the position detector 3 according to the present embodiment are other two. A harmonic component may be included by superimposing the phase sine wave signal. Even in such a case, a two-phase sine wave signal having an ideal sine waveform can be obtained by performing sine wave fitting. In addition, about the method of this sine wave fitting, the least square method may be used and another method may be used.

  The phase difference calculation means 12 calculates a phase difference based on the two-phase sine wave signal idealized by the sine wave fitting means 11 and outputs a phase correction value.

  The phase correction value update determination unit 13 recognizes the angle of the motor 1 from the angle data calculated by the angle calculator 7 and determines whether or not to update the phase correction value.

  Here, for example, when the Z signal is generated in the analog signal generation unit 4, the Z phase signal is superimposed on the two-phase sine wave signal, distortion occurs in the vicinity of the Z phase signal, and the phase difference may change. is there. Therefore, the phase correction value update determination unit 13 specifies the position of the Z-phase signal from the angle of the motor 1, and uses the phase correction value input from the phase difference calculation unit 12 in the vicinity of the specific position as the signal correction unit 6. Output to. Thus, by specifying the position where the phase difference changes and outputting the phase correction value, it is possible to effectively correct the phase difference. Even when the analog signal generator 4 does not output a Z-phase signal, if a specific position where the phase difference fluctuates during one rotation of the motor 1 is known in advance, the phase correction value at that position Is output, it is possible to effectively correct the phase difference.

  As described above, according to the position detector according to the embodiment, the idealized two-phase sine is obtained by fitting the two-phase sine wave signal generated by the analog signal generation unit 4 to an ideal sine waveform. Since the phase difference is calculated based on the wave signal, the phase difference can be accurately calculated even when a distortion occurs due to the harmonic component superimposed on the two-phase sine wave signal. Detection can be performed.

  Further, from the angle data calculated by the angle calculator, the position where the phase difference fluctuates during one rotation of the motor is specified, and the phase correction value is corrected so that the phase difference is corrected at the specific position where the phase difference fluctuates. Therefore, the phase difference can be effectively corrected.

  Note that the configuration shown in the above embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part thereof is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

DESCRIPTION OF SYMBOLS 1 Motor 2 Servo amplifier 3 Position detector 4 Analog signal generation part 5 AD converter 6 Signal correction part 7 Angle calculation part 8 Phase correction value calculation part 11 Sine wave fitting means 12 Phase difference calculation means 13 Phase correction value update determination means

Claims (2)

A position detector for detecting the position of a motor,
An analog signal generation unit that generates an analog signal of each of a plurality of two-phase sine waves that are proportional to the rotational speed of the motor and have orthogonality;
An AD converter that converts each instantaneous value obtained by sampling each phase analog signal at equal intervals to each phase digital signal;
A phase correction value calculation unit for calculating a phase correction value of each phase digital signal;
Based on the phase correction value, a signal correction unit that corrects and outputs the phase difference of each phase digital signal to 90 degrees, and
Based on each phase output signal of the signal correction unit, an angle calculation unit that calculates a motor angle that is position information of the motor;
With
The phase correction value calculator is
Sine wave fitting means for fitting and outputting each phase digital signal to a sine waveform;
Based on each phase output of the sine wave fitting means, a phase difference calculating means for calculating and outputting the phase correction value;
A position detector comprising: A position detector for detecting the position of a motor,
An analog signal generation unit that generates an analog signal of each of a plurality of two-phase sine waves that are proportional to the rotational speed of the motor and have orthogonality;
An AD converter that converts each instantaneous value obtained by sampling each phase analog signal at equal intervals to each phase digital signal;
A phase correction value calculation unit for calculating a phase correction value of each phase digital signal;
Based on the phase correction value, a signal correction unit that corrects and outputs the phase difference of each phase digital signal to 90 degrees, and
Based on each phase output signal of the signal correction unit, an angle calculation unit that calculates a motor angle that is position information of the motor;
With
The phase correction value calculator is
Sine wave fitting means for fitting and outputting each phase digital signal to a sine waveform;
Phase difference calculation means for calculating the phase correction value based on each phase output of the sine wave fitting means;
Based on the angle data, the position of the motor where the phase difference of each phase analog signal changes is specified, and the phase correction value update determination means for updating and outputting the phase correction value at the specified position;
A position detector comprising:

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