JPH08128855A - Speed detecting device - Google Patents

Abstract

PURPOSE: To provide a speed detecting device of high-speed response which is not affected by the duty ratio of a pulse encoder and phase shift, by providing a storage device which stores correction factor and a discriminating device which discriminates the phase of the pulse encoder output, etc. CONSTITUTION: A pulse encoder 1 is directly coupled with a rotational body 2, and its output is two phases of rectangular waves A and B of frequency proportional to rotating speed of the rotational body 2. Into a fourfold multiplier circuit 3, the outputs of the encoder 1, the rectangular waves A and B, are inputted, and the pulse wherein the inputted frequency was multiplied fourfold is outputted from it. A pulse-to-pulse speed calculator 4 outputs average speed Nml. A phase discriminating device 6 outputs phase Px based on the states of the rectangular waves A and B. A correction factor selecting device 8, based on the phase Px, selects a correction factor Kx stored in a correction factor storage deice 7 and outputs it. A corrector 9 outputs an average speed Nam corrected by the correction factor. When the correction factor Kx is set and stored, the correction factor Kx is found from the output Nbm of a four-pulse speed calculator 5 with a correction factor calculator 10, and set through a switch 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed detecting device used particularly in a motor control device or the like having improved speed detection accuracy and response in a low speed range.

[0002]

2. Description of the Related Art A description will be given with reference to FIGS. Figure 2
Shows a conventional example, 1 is a pulse encoder, 2 is a rotary body, 3 is a quadrupling circuit, and 4 is a speed calculator for one pulse. FIG. 4 shows an example of the relationship between the pulse encoder and the quadruple pulse. That is, the pulse encoder 1 is directly connected to the rotating body 2, and the output of the pulse encoder 1 is a three-phase rectangular wave having a frequency proportional to the rotation speed of the rotating body 2.
The quadrupling circuit 3 inputs the two-phase rectangular waves A and B output from the pulse encoder 1, generates pulses at the rising and falling edges of each waveform as shown in FIG. 4, and outputs a pulse obtained by multiplying the input frequency by four. Is output.

Further, the one-pulse speed calculator 4 performs a calculation as in the equation (1) from the output of the quadrupling circuit 3 and outputs a signal. Nm1 = Gn / (Tm-Tm-1) (1) That is, the time between each pulse of the output of the quadruple multiplication circuit 3 is detected and the reciprocal thereof is calculated. , The average speed of the rotating body 2 between each pulse is obtained. Here, Gn is a conversion gain, T
m-1 is the pulse time one pulse before the pulse time Tm, and Nm1 is the average speed from the pulse time Tm-1 to the pulse time Tm.

FIG. 3 shows another conventional example, and 5 is a 4-pulse speed calculator. That is, in FIG.
A 4-pulse inter-speed calculator 5 is used in place of the 1-pulse inter-speed calculator 4 shown in FIG.
The pulse time is measured, the reciprocal thereof is calculated, and the average speed of the rotating body 2 during four pulses is calculated and output. The calculation is represented by Expression (2). Nm4 = 4Gn / (Tm-Tm-4) (2) where Nm4 is the average speed from the pulse time Tm-4 to the pulse time Tm.

[0005]

In the prior art of this kind, the duty ratio of the rectangular wave output from the pulse encoder is not completely 50%, and even if the rotating body rotates at a constant speed, for example, ( Tm-2 -Tm-4) and (Tm-Tm-
2) and (Tm-1 -Tm-3) and (Tm + 1 -Tm-1) are not necessarily equal. Also, the phase difference between the rectangular wave A and the rectangular wave B is not necessarily 90 degrees. In this way, the time between the pulses is not equal even when the rotating body is rotating constantly, so the output of the speed detection device shown in FIG. 2 is not a constant value, and further, the speed detection value has ripples. It occurs and the speed cannot be detected correctly. Further, the speed detection device shown in FIG. 3 obtains the average speed between four pulses and there is no speed detection error due to the deviation of the duty ratio or the deviation of the phase described above. It can be detected completely 4 pulses after the speed change, and the detection response becomes slower. Therefore, an object of the present invention is to provide a high-accuracy and high-speed response speed detection device that is not affected by the duty ratio or phase shift of the pulse encoder.

[0006]

The present invention has been made in view of the above points, and means for solving the problems are as follows. (1) A pulse encoder that outputs a two-phase rectangular wave at a frequency proportional to the rotation speed of a rotating body, a quadruple multiplication circuit that inputs a pulse encoder output and outputs a pulse that is quadruple that frequency, and a quadruple multiplication circuit In a speed detection device equipped with a one-pulse speed calculator that detects the rotational speed of a rotating body by measuring the time between output pulses and calculating the reciprocal thereof, a correction coefficient storage device that stores four correction coefficients And a phase discriminator that inputs a two-phase rectangular wave of the pulse encoder output and discriminates into four phases, and a correction coefficient selector that selects and outputs four correction coefficients in the correction coefficient storage by the phase discriminator output. And a compensator for computing and outputting the rotational speed of the rotating body corrected by the rotational speed of the output of the speed calculator for one pulse and the correction coefficient of the output of the correction coefficient selector.

(2) Further, a 4-pulse speed calculator for detecting the rotation speed of the rotating body by measuring the time of 4 pulses of the output of the quadruple circuit and calculating the reciprocal thereof;
A correction coefficient calculator that inputs the inter-pulse speed calculator output and the one-pulse speed calculator output to calculate the correction coefficient, and outputs the correction coefficient calculator output to the correction coefficient memory selected by the phase discriminator output And a correction coefficient setting device. (3) Furthermore, an automatic measurement setting device that automatically measures the electrical constants and mechanical constants of the rotating body and sets the correction coefficient setting device in the drive device that drives the rotating body operates. It is designed to operate when you are.

[0008]

The duty ratio and phase shift of the output waveform of the pulse encoder, which was pointed out as a problem in the above-mentioned problems, hardly changes in each cycle of the output waveform of the pulse encoder. Here, as shown in FIG. 4, in the four phases P1 to P4 determined by the states of the rectangular waves A and B of the pulse encoder output, for example, the time of the same phase P1 (Tm-3 −Tm-4 ) And (Tm + 1 −T
m) will be equal if the rotation speed is constant.

That is, since the speed detection error due to the duty ratio and the phase shift depends on the phase P1 to the phase P4, the correction coefficient Kx corresponding to each phase is used, and the corrected average speed Nam is calculated by the equation (3). ), The average speed Nm1 obtained by the equation (1) can be corrected. Nam = Nm1 · (1 + Kx) (3) However, the correction coefficient Kx is the correction coefficient K1, K2, K3, K
There are four (4), and each corresponds to the phases P1 to P4. In this way, the phase discriminator discriminates the phases P1 to P4 from the output waveform of the pulse encoder and sets them as Px, and the correction coefficient selector selects the correction coefficient K1 to the correction coefficient K4 corresponding to the discriminated phase Px. It is possible to select one and output it as Kx, calculate the equation (3) by the corrector, and output the corrected average speed Nam as the speed detection value.

Then, the correction coefficient Kx is expressed by the equation (3) as Kx
It can be obtained from the equation (4) solved in. Kx = Nbm / (Nm-1) (4) Here, the average speed Nbm must be the actual speed, and FIG.
The speed detected by the 4-pulse speed calculator may be used as in the circuit. The time between four pulses corresponds to one period of the rectangular wave before being multiplied by four, and the four-pulse speed calculator has no influence on the duty ratio or the phase. The correction coefficient calculator calculates the formula (4), and the correction coefficient setting unit selects the correction coefficient storage unit according to the output of the phase discriminator.
Obviously it can be set.

It is not necessary to always set the correction coefficient, and for example, automatic measurement for automatically measuring the electric constants and mechanical constants of the rotating body and setting them in the drive device for driving the rotating body When the setting device is operating, the correction coefficient setting device may be simultaneously operated to store and set the four correction coefficients. After that, highly accurate speed detection can be performed without changing the correction coefficient. Of course, the speed detection is accurate during one pulse, and the speed detection response is faster than the speed detection during four pulses. The present invention will be described in more detail by way of examples.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of the essential part of an embodiment of the present invention in a manner similar to FIGS. 2 and 3, where 6 is a phase discriminator, 7 is a correction coefficient memory and 8 is a correction coefficient selector. Vessel, 9 is a compensator, 10
Is a correction coefficient calculator, 11 is a correction coefficient setter, and 12 is a switch. In FIG. 1, a pulse encoder 1, a rotating body 2,
The connection configuration including the quadruple multiplication circuit 3 and the one-pulse speed calculator 4 is the same as that of the circuit of FIG. Further, a connection configuration is provided by providing a 4-pulse arithmetic circuit 5, a phase discriminator 6, a correction coefficient memory 7, a correction coefficient selector 8, a corrector 9, a correction coefficient calculator 10, a correction coefficient setter 11 and a switch 12. It has been done. The operation of such a connection configuration is as follows.

That is, the pulse encoder 1 is a rotating body 2
The output is a two-phase rectangular wave having a frequency proportional to the rotation speed of the rotating body 2. The quadruple multiplication circuit 3 inputs the rectangular waves A and B output from the pulse encoder 1 and outputs a pulse obtained by multiplying the input frequency by four. The one-pulse speed calculator 4 outputs the average speed Nm1 as a signal according to the equation (1). The phase discriminator 6 inputs the rectangular waves A and B and outputs the phase Px based on their states. Correction coefficient selector 8
Selects the correction coefficient of the correction coefficient storage unit 7 according to the phase Px and outputs it as the correction coefficient Kx. The correction coefficient Kx is input to the corrector 9, and a signal is output by using the corrected average speed Nam as a speed detection value according to the equation (3).

When the correction coefficient Kx is set and stored, the switch 12 is turned on and the 4-pulse speed calculator 5 calculates the equation (2). The output Nm1 is set to Nbm, and the equation (4) is calculated. The correction coefficient calculator 10 uses the correction coefficient Kx
Is required. It is set and stored in the selected correction coefficient storage device 7 via the correction coefficient setting device 11.

[0015]

As described above, according to the present invention, even if the duty ratio or the phase of the pulse encoder is deviated, it is possible to detect the speed with high accuracy without delaying the detection response, and it can be applied to a wide field. The practical effect is remarkable.

[Brief description of drawings]

FIG. 1 is a block system diagram showing an embodiment of the present invention.

FIG. 2 is a block system diagram showing a conventional example.

FIG. 3 is a block system diagram showing another conventional example.

FIG. 4 is a waveform diagram showing an example of a relationship with a pulse encoder quadruple pulse.

[Explanation of symbols]

 1 pulse encoder 2 rotating body 3 4 multiplication circuit 4 1 pulse speed calculator 5 4 pulse speed calculator 6 phase discriminator 7 correction coefficient memory 8 correction coefficient selector 9 corrector 10 correction coefficient calculator 11 correction coefficient setting Unit 12 Switch A Square wave B Square wave Nm1 Average speed Nm4 Average speed Nam Average speed Nbm Average speed

Claims (2)

[Claims] 1. A pulse encoder that outputs a two-phase rectangular wave at a frequency proportional to the rotational speed of a rotating body, and a quadrupling circuit that inputs the pulse encoder output and outputs a pulse obtained by quadrupling the frequency. A plurality of correction coefficients are stored in a speed detection device including an inter-pulse speed calculator that measures the time between pulses of the quadruple circuit output, calculates the reciprocal of the time, and detects the rotation speed of the rotating body. Storage means, discrimination means for obtaining the pulse encoder output to discriminate into a plurality of phases, selection means for selecting and outputting a correction coefficient of the storage means by the discrimination means output, and pulse-to-pulse velocity calculator output A speed detecting device, comprising: a correction means for calculating and outputting a rotation speed and a rotation speed corrected by a correction coefficient output from the selecting means. 2. A 4-pulse speed calculator for measuring the time of 4 pulses of the 4-multiplier circuit output and calculating the reciprocal thereof to detect the rotation speed of the rotating body, and an output of the 4-pulse speed calculator. And a correction coefficient calculator for inputting the pulse-to-pulse speed calculator output to calculate a correction coefficient, and a correction coefficient setter for outputting the correction coefficient calculator output to the storage means selected by the discrimination means output. The speed detection device according to claim 1, wherein the speed detection device is provided.