JPS5925977B2 - Rotation direction and speed detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a rotation direction and speed detection device that uses a three-phase AC speed generator and detects not only the rotation speed but also the rotation direction.

Conventionally, as a method for simultaneously detecting the rotational direction and rotational speed in an analog manner, it is common to use a DC speed generator.

However, since DC speed generators have a commutator and brushes, when used as a detection part in an automatic control system that requires high reliability, maintenance issues remain, and the price is higher than that of AC speed generators. It's much more expensive than that. In view of these, the present invention uses a three-phase AC speed generator, which has no commutator or brush, has high stability, and is inexpensive, instead of a DC speed generator, and compares the phase rotation of its three-phase output. This system uses logic elements such as D-flip-flops and D-flip-flops, and detects and determines the rotation direction without a transformer.This will be explained in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a circuit diagram of the embodiment, and FIG. 2 is a time chart for explaining its operation.

In Fig. 1, 1 is a three-phase AC speed generator, 2 is a rectifier circuit for rectifying the three-phase output of the AC generator 1, 3 and 4 are resistors for creating the midpoint of the rectified output, and 5 and 6 are resistors for rectifying the three-phase output of the AC generator 1. The voltage at the midpoint is compared with each voltage of the R phase and the T phase, and the comparator T which obtains a rectangular wave output with a width of A D-flip-flop outputs a logical output corresponding to the phase rotation, and 8 represents a switch element that is switched by the output.In other words, the present invention is a conventional AC speed generator that combines a three-phase AC speed generator 1 and a rectifier 2. Two resistors 3, 4 and two comparators 5, 6 to obtain the rectified output midpoint voltage in speed detection by
and a D-flip-flop T, the phase rotation of the three-phase AC output is detected without a transformer, and the detection signal is used to switch the switch element 8 to convert the polarity of the rectified output and also determine the direction of rotation. The present invention is configured as described above.

Next, the operation will be explained with reference to the time chart shown in FIG. In Fig. 2, A is the three-phase output voltages R, S, and T of the three-phase AC speed generator 1, the midpoint voltage N of the rectified output, and the R-phase voltage VR-N seen from the midpoint, as well as the T-phase voltage VT.
In each waveform diagram of -N, the opening and C are the 18 square wave outputs from the comparators 5 and 6. Each represents. This square wave output is input to the DJ flip-flop 7. For example, if the phase rotation is in the time direction, the "fall b" of the T-terminal input of the D-flip-flop is always within the "HM level period" of the D-terminal input. Therefore, its output is always [1], and conversely, if the phase rotation is in the opposite direction to the time direction, the T terminal input will fall when the D terminal input is at the 11LI゛ level. The output is always [0]. The truth table of the D-flip-flop is as follows. As described above, the switch element 8 is switched by the output of the D-flip-flop, and the direction of large rotation is detected by the rectified output produced at either the terminals 9 or 10.

The reason why the rectified output is divided by resistors 3 and 4 and the midpoint voltage N is compared with the three-phase AC output is to obtain a 180-width rectangular wave synchronized with each phase voltage without a transformer. can be,
As a result, the input waveform to the comparator approaches a rectangular wave, as shown by RN and VT-N in FIG. The midpoint voltage N is obtained by dividing the rectified output of the voltage between the R, S, and T phases by resistors 3 and 4 of the same value, and the rectified output is divided between the R phase and S phase as shown in Figure 2 Mode I, which is also shared by R
A mode in which the share is shared between the phase and T phase, a mode in which the share is shared between the S phase and the T phase, a mode in which the share is shared between the S phase and the R phase, a mode in which the share is shared between the T phase and the R phaseV. It can be determined by calculating the average value of the phase voltage for each case of the mode shared by the T phase and the S phase. That is, the R phase voltage is ESin(l)T.
The s-phase voltage is Esin (ωt-Kπ), and the T-phase voltage is Esi.
Calculating the mode I and the midpoint voltage N at which the mode falls is as follows, where n(ωt+sign π). Mode I, ωt
=π/6 to π/2 mode, ωt2π/2 to 5π/6 The following table shows the relationship between the above equations (1) and (2) and ωt for each mode.

Since the midpoint voltage N is obtained as described above, each phase voltage seen from the midpoint can be obtained by subtracting the midpoint voltage N from each phase output voltage of the alternator 1, resulting in the VR-N waveform shown in Fig. 2. ,VT-N
Waveforms can be obtained.

As described above, the present invention uses a three-phase alternating current generator and detects the phase rotation of the three-phase output, thereby making it possible to determine the rotation direction. is detected by comparing the midpoint voltage of the three-phase rectified output with the voltage of each phase.
There is no need to insulate between the outputs, and phase detection can be performed reliably even in areas where the rotation speed is low and the generator output is small. Furthermore, the configuration includes two comparators, a D-flip-flop, and a rectifier output switch. It has excellent features such as extremely simple switching elements, and is advantageous in terms of reliability and cost compared to DC speed generators.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a time chart for explaining its operation. 1... Three-phase AC speed generator, 2... Rectifier circuit, 3,
4...Resistor, 5, 6...Comparator, 7...D-
Flip-flop, 8... switch element.

Claims (1)

[Claims] 1. A rectifier circuit that full-wave rectifies the three-phase AC output of a three-phase AC speed generator, two resistors connected in series between the positive and negative polarities of the output terminal of the rectifier circuit to obtain the midpoint voltage of this rectifier circuit output. Compare the midpoint voltage of the connection point of these two resistors with any two-phase AC output among the three-phase AC outputs, and output a 180° width rectangular wave output synchronized with this two-phase AC output. The output terminal of one of these two comparators is connected to the D input terminal, the output terminal of the other comparator is connected to the T input terminal, and the output terminal of the two comparators is connected to the T input terminal. D- converts the phase relationship of the rectangular wave output into a logic signal of "1" or "0"
A flip-flop, a control terminal is connected to the output terminal of this D-flip-flop, and is activated by the logic signals of "1" and "0", and an input is connected to the output terminal of the rectifier circuit, and the polarity of the output of the rectifier circuit is controlled. A rotation direction and speed detection device comprising a switch element for switching, the output terminal of the switch element serving as an output terminal.