JP2008089409A - Rotational speed detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotational speed detector capable of improving the reliability of a detected rotational speed. <P>SOLUTION: A timing generating circuit 22 detects the rotational speed of a resolver 1 based on a signal of the resolver 1 digital-converted by an R/D converter 20. The timing generating circuit 22 makes each latch circuit section 24 store one-rotation duration of the resolver 1 whenever the resolver 1 rotates by an angle obtained by dividing 360 degrees into plurality. A selection circuit 26 selects the last one-rotation duration based on the information from the timing generating circuit 22. A speed calculation section 27 calculates the rotational speed of a monitoring object based on the one-rotation duration selected by the selection circuit 26. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotational speed detector using a resolver, and more particularly to a new improvement for improving the reliability of a detected rotational speed.

  In the conventional apparatus, the signal from the resolver indicating the rotation angle of the monitoring target is digitally converted by the resolver / digital converter (R / D converter), and the converted signal is differentiated to obtain the unit time of the monitoring target. The winning rotation angle, that is, the rotation speed of the monitoring target is detected (for example, see Patent Document 1).

JP 2003-149258 A

  By the way, even if the monitoring target is rotated at a constant speed, a specific error occurs due to the combination of the sensor (resolver) and the R / D converter in the R / D conversion, and the output of the R / D converter is as shown in FIG. A straight line is not drawn as shown in FIG. Therefore, when the rotation speed of the monitoring target is obtained by differentiating the signal digitally converted by the R / D converter as in the conventional device as described above, due to the error of R / D conversion (rotation angle detection), A speed ripple (speed jitter) as shown in FIG. 5 occurs in the rotational speed to be detected, and the precision of rotational speed detection is reduced.

  The error of R / D conversion is peculiar to the combination of the sensor (resolver) and the R / D converter, and the error reproducibility is extremely high. A method of detecting the rotational speed of the monitoring object from the time required for one revolution of the resolver using the reproducibility of the error is also conceivable. However, if an attempt is made to detect the rotation speed to be monitored from the time required for one rotation, the rotation speed can be detected only for each rotation, and the reliability of the detected rotation speed is reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotational speed detector that can improve the reliability of the detected rotational speed.

  The rotational speed detector according to the present invention detects the rotational angle of the resolver connected to the rotating monitoring target and the resolver, and counts the time required for one rotation every time the resolver rotates 360 degrees divided into a plurality of angles. And a rotational speed detecting means for obtaining the rotational speeds to be monitored from the counted plurality of required time for one rotation.

  According to the rotational speed detector of the present invention, the rotational speed detecting means detects the rotational angle of the resolver, and starts counting the time required for one rotation every time the resolver rotates at an angle divided by 360 degrees. Since the rotation speeds to be monitored are respectively obtained from the counted time required for one rotation, the frequency of rotation speed detection can be increased, and the reliability of the detected rotation speed can be improved.

The best mode for carrying out the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
1 is a block diagram showing a rotational speed detector according to Embodiment 1 of the present invention. In the figure, a resolver 1 connected to a rotating monitoring target such as a rotating shaft of a motor is connected to a rotational speed detecting means 2. The rotation speed detection means 2 detects the rotation angle of the resolver 1 and takes one rotation required time (the rotor of the resolver 1 makes one rotation each time the resolver 1 rotates 360 degrees divided into a plurality of angles). Time) is started, and the rotation speeds to be monitored are respectively obtained from the counted time required for one rotation. More specifically, the rotation speed detection means 2 starts counting the time required for one rotation every time the resolver 1 rotates by an angle obtained by equally dividing 360 degrees. A drive control device 3 is connected to the rotation speed detecting means 2. The drive control device 3 performs drive control of the monitoring target based on the rotation speed detected by the rotation speed detection means 2.

  Hereafter, the structure of the rotational speed detection means 2 is demonstrated concretely. The rotational speed detection means 2 includes a resolver / digital converter (R / D converter) 20, an amplifier 21, a timing generation circuit 22, a timer 23, a plurality of latch circuit sections 24, a plurality of subtraction circuits 25, a selection circuit 26, and A speed calculation unit 27 is included.

  The R / D converter 20 converts the signal 1a from the resolver 1 into a digital signal. The R / D output signal 20 a output from the R / D converter 20 is input to the amplifier 21 and the timing generation circuit 22. The amplifier 21 amplifies the input R / D output signal 20a and feeds back the amplified signal to the R / D converter 20 as an excitation signal 21a.

  The timer 23 includes a crystal resonator 23a that emits clock pulses and an UP counter 23b that counts the clock pulses. The UP counter 23b counts clock pulses, and outputs timer information 23c that indicates the accuracy to the microsecond (μs) unit. Each latch circuit unit 24 stores (latches) the timer information 23c from the UP counter 23b.

  The timing generation circuit 22 detects the rotation angle of the resolver 1 based on the R / D output signal 20 a of the R / D converter 20. In addition, the timing generation circuit 22 sequentially inputs a start time storage command 22a to each latch circuit unit 24 every time the resolver 1 rotates by an angle divided by 360 degrees. Further, the timing generation circuit 22 inputs an end time storage command 22b to the latch circuit portion 24 when the resolver 1 makes one rotation after the start time storage command 22a is input to any of the latch circuit portions 24. Each latch circuit unit 24 includes a start time latch circuit 24a that stores timer information 23c (timer information 23c when one revolution of the resolver 1 starts) when the start time storage command 22a is detected, and an end time storage command 22b. One set each includes an end time latch circuit 24b for storing timer information 23c (timer information 23c when one revolution of the resolver 1 is completed).

  More specifically, the timing generation circuit 22 sends a start time storage command 22a to each latch circuit unit 24 every time the R / D output signal 20a from the R / D converter 20 is displaced by a predetermined level. Enter in order. Here, as shown in FIG. 4, the R / D output signal 20a includes a specific error due to the combination of the resolver 1 and the R / D converter 20, so that the resolver 1 equally divides 360 degrees. The R / D output signal 20a is not precisely output every time the angle is rotated. That is, the timing generation circuit 22 sequentially inputs the start time storage command 22a to each latch circuit unit 24 every time the resolver 1 rotates by an angle obtained by dividing 360 degrees substantially equally. Further, the timing generation circuit 22 inputs the start time storage command 22a to any one of the latch circuit sections 24, and then the level of the R / D output signal 20a inputs the start time storage command 22a to the latch circuit section 24. Is detected, the resolver 1 is detected to make one rotation, and an end time storage command 22b is input to the latch circuit unit 24.

  Each subtraction circuit 25 obtains the time required for one revolution of the resolver 1 based on the timer information 23c stored in each start time latch circuit 24a and each end time latch circuit 24b.

  The timing generation circuit 22 inputs the detected rotation angle information 22 c to the selection circuit 26. The selection circuit 26 selects the latest one-revolution required time from the one-revolution required time calculated by each subtraction circuit 25 based on the rotation angle information 22 c from the timing generation circuit 22.

The speed calculation unit 27 calculates the rotation speed to be monitored based on the time required for one rotation selected by the selection circuit 26. Assuming that the time required for one rotation is T (μs), the rotation speed Vr (min ⁻¹ ) can be expressed by the following equation.
Vr = (10 ⁶ / T) × 60 (1)
If T is 9998 (μs),
Vr ⁼ a (10 6/9998) × 60 = 6001 (min -1).
That is, the rotational speed detection means 2 of this embodiment performs speed detection with a resolution of 1 (min ⁻¹ ) by measuring time with a resolution of 1 (μs).

  Next, the operation will be described. FIG. 2 is an explanatory diagram showing the time required for one revolution of the resolver 1 stored in each latch circuit section 24 of FIG. FIG. 3 is an explanatory diagram showing the rotational speed of the monitoring target calculated by the speed calculation unit 27 of FIG. Here, it is assumed that the nine rotational speed detecting means 2 are provided with nine latch circuit sections 24 each storing the required time for one rotation T1 to T9. As shown in FIG. 2, the R / D output when the resolver 1 rotates a plurality of times has a similar waveform repetition. That is, the reproducibility of the R / D conversion error is extremely high, and the error in position detection accuracy (rotation angle detection accuracy) for each rotation is extremely small. Therefore, it is possible to accurately count one rotation required time T1 to T9 every time the resolver 1 rotates 45 degrees, and the rotation speed to be monitored calculated by the speed calculation unit 27 includes only a small speed ripple as shown in FIG. Absent.

In such a rotation speed detector, the rotation speed detection means 2 detects the rotation angle of the resolver 1 and starts counting the time required for one rotation every time the resolver 1 rotates 360 degrees divided into a plurality of angles. Since the rotation speeds to be monitored are respectively obtained from the counted time required for one rotation, the frequency of rotation speed detection can be increased, and the reliability of the detected rotation speed can be improved.
Further, in the conventional apparatus, it is necessary to make full use of a digital filter in order to eliminate the speed ripple, and there is a time lag in the detected rotational speed. However, in the rotational speed detector of this embodiment, the speed ripple is kept small. Therefore, it is possible to eliminate the need to make full use of the digital filter, and to detect the rotational speed instantaneously.

  Further, the rotation speed detection means 2 starts counting the time required for one rotation every time the resolver 1 rotates 360 degrees equally divided, so that the rotation speed can be detected at equal intervals, and the detected rotation speed is used. It is possible to facilitate the drive control of all monitored objects.

  Further, the rotation speed detection means 2 includes a resolver / digital converter 20 that converts a signal from the resolver 1 into a digital signal, a timer 23 that outputs timer information 23c, and a plurality of latch circuit units 24 that store the timer information 23c. Then, the rotation angle of the resolver 1 is detected based on the output of the resolver / digital converter 20, and the timer information 23c is sequentially stored in each latch circuit unit 24 every time the resolver 1 rotates 360 degrees divided into a plurality of angles. In addition, a timing generation circuit 22 that further stores the timer information 23c at that time in the latch circuit unit 24 when the resolver 1 rotates once after the timer information 23c is stored in any of the latch circuit units 24, and each latch A plurality of subtraction circuits each for determining the time required for one rotation based on the timer information 23c stored in the circuit unit 24 5, a selection circuit 26 that selects the latest one-revolution required time based on the information 22 c from the timing generation circuit 22, and a speed calculation that calculates the rotation speed to be monitored from the one-revolution required time selected by the selection circuit 26. And the rotation speed of the monitoring target can be detected with higher accuracy.

  In the first embodiment, it has been described that nine rotation circuit units 24 are provided in the rotation speed detection unit 2, but the number of latch circuit units is arbitrary. If 360 latch circuit units can be mounted, the rotational speed every time the resolver rotates once can be detected.

  In the first embodiment, it has been described that the rotation speed detection unit 2 starts counting the time required for one rotation every time the resolver 1 rotates at an angle divided by 360 degrees. May be counted every time it takes 360 degrees to rotate at an angle that is divided unevenly.

Further, in the first embodiment, the rotation speed detecting means 2 has one timer 23 and a plurality of latch circuit sections 24 in order to obtain a time required for one rotation every time the resolver 1 rotates 360 degrees divided into a plurality of angles. However, there are other possible structures for obtaining the time required for one rotation every time the resolver 1 rotates 360 degrees divided into a plurality of angles.
For example, the rotation speed detecting means includes a resolver / digital converter that converts a signal from the resolver into a digital signal, a plurality of timers that output timer information, and a rotation of the resolver based on the output of the resolver / digital converter. An angle is detected, and each time the resolver rotates 360 degrees divided into a plurality of angles, a count start command is sequentially input to each timer, and when the resolver makes one rotation after issuing the count start command, A timing generation circuit that inputs a count end command to the timer that has input the count start command and outputs timer information indicating the time required for one rotation to the timer, and indicates the time required for one rotation from the timer A speed calculation unit that calculates the rotation speed of the monitoring target based on timer information.

It is a block diagram which shows the rotational speed detector by Embodiment 1 of this invention. FIG. 2 is an explanatory diagram showing a time required for one revolution of a resolver stored in each latch circuit unit of FIG. 1. It is explanatory drawing which shows the rotational speed of the monitoring object which the speed calculation part of FIG. 1 calculates. It is explanatory drawing which shows the rotational speed detection in a conventional apparatus. It is explanatory drawing which shows the rotational speed of the monitoring target detected with the conventional apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Resolver, 2 Rotational speed detection means, 3 Drive control apparatus, 20 R / D converter (resolver / digital converter), 20a R / D output signal, 22 Timing generation circuit, 22c Rotation angle information, 22a Start time storage command 22b End time storage command, 23 timer, 23c timer information, 24 latch circuit section, 25 subtraction circuit, 26 selection circuit, 27 speed calculation section.

Claims (3)

A resolver (1) connected to a rotating monitoring target;
The rotation angle of the resolver (1) is detected, and each time the resolver (1) rotates 360 degrees divided into a plurality of angles, the time required for one rotation is started. A rotational speed detector comprising: a rotational speed detection means (2) for determining the rotational speed of each of the monitoring targets.   The rotational speed detection unit according to claim 1, wherein the rotational speed detection means (2) starts counting the time required for one rotation every time the resolver (1) rotates at an angle divided by 360 degrees. vessel.   The rotation speed detection means (2) includes a resolver / digital converter (20) that converts a signal from the resolver (1) into a digital signal, a timer (23) that outputs timer information (23c), and the timer A rotation angle of the resolver (1) is detected on the basis of outputs of a plurality of latch circuit units (24) for storing information (23c) and the resolver / digital converter (20). The timer information (23c) is stored in order in each latch circuit unit (24) every time the angle is divided into a plurality of degrees, and the timer information (23c) is stored in any one of the latch circuit units (24). When the resolver (1) makes one rotation after being stored, the timer information (23c) at that time is further stored in the latch circuit unit (24) ( 2), a plurality of subtraction circuits (25) for obtaining the time required for one rotation based on the timer information (23c) stored in each latch circuit section (24), and the timing generation circuit (22) A selection circuit (26) for selecting the latest one-revolution required time based on the information (22c) from the control circuit, and calculating the rotation speed of the monitoring target from the one-revolution required time selected by the selection circuit (26). The rotation speed detector according to claim 1, further comprising: a speed calculation unit (27) that performs the operation.

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