JPS62236377A - Wire disconnection detector for speed controller - Google Patents

Abstract

PURPOSE:To detect the abnormal operation of a speed controller by detecting the wire disconnection of a speed detector only when a speed set signal of predetermined value or higher is inputted. CONSTITUTION:A speed setting signal is inverted by an inverting amplifier 12, and inputted to an addition type comparator 13 as comparing means together with preset voltage. After the output of an adder 13 is inverted by an inverter 14, it is inputted to an addition type comparator 16 as comparing means together with a speed feedback signal through a negative power line voltage and a buffer 15. When a speed detector is wire-disconnected, a speed feedback signal becomes zero, the output of the comparator 16 becomes a high level, and the transistor 171 of an open collector 17 is turned ON.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a disconnection detection circuit for a speed control device that controls the speed of a rotating electric machine by comparing a speed setting signal and a speed feedback signal.

(Prior Art) Conventionally, for example, in a speed control device for a rotating electrical machine that positions a processing table of a machine tool, a speed setting device outputs a speed setting signal consisting of an analog electric signal to a speed command value calculation circuit, and on the other hand, The speed of a rotating machine, such as an induction motor, is detected by a speed detector such as a 7-oto encoder to obtain a speed detection signal consisting of a digital electric signal, and this speed detection signal is converted into a speed detection signal consisting of an analog electric signal by a frequency-voltage converter. These speed setting signals and speed detection signals are compared and calculated in the speed command calculation circuit, and the speed detection signal matches the speed setting signal based on this calculation output signal. A motor is provided in which the speed of the induction motor is increased or decreased through an inverter.

(Problem to be Solved by the Invention) However, in the conventional configuration described above, if the speed detector is disconnected, the speed detection signal becomes a zero signal, so the speed command value circuit always increases the speed. There is a problem that the direction calculation output signal is output, and the speed of the induction motor increases, resulting in an uncontrollable state where the induction motor continues to slow down. Therefore, when such an abnormality occurs, the induction motor There is a problem in that the processing table driven by the machine collides with the end at high speed.

The present invention has been made in view of the above circumstances, and its object is to provide a disconnection detection circuit for a speed control iD device that can immediately output a disconnection detection signal when a speed detector that detects the speed of a rotating machine is disconnected. Our goal is to provide the following.

[Structure of the Invention] (Means for Solving the Problem) That is, the present invention controls a rotating electrical machine by comparing a speed setting signal and a speed feedback signal, in which the speed setting signal is equal to or higher than a predetermined value. a speed setting signal detecting means for detecting the speed setting signal, and a speed setting signal detecting means for detecting the speed setting signal; The present invention is characterized in that it comprises a comparison means for comparing the voltage signal with the voltage signal and outputting a disconnection detection signal.

(Function) According to the above-described configuration, when a speed setting signal equal to or higher than a predetermined value is input, a detection signal is output from the speed setting signal detection means, and upon receiving this detection signal, the comparison circuit detects the speed from the rotating electric machine. A disconnection is detected by comparing the feedback signal and a voltage signal corresponding to a predetermined rotation speed.

(Example) Hereinafter, an example in which the present invention is applied to a speed control device for a rotating electrical machine that positions a processing table of a machine tool will be described with reference to the drawings.

First, the electrical configuration of the speed control device 1 will be described according to FIG. 2 is a positioning device having a processing table, and is driven by an induction motor 3 which is a rotating electric machine. The rotational speed of the induction motor 3 is converted into an electrical signal by a speed detection circuit 6 consisting of a speed detector and a signal converter.

First, the photo encoder 4, which is a speed detector, is the induction motor 3.
A speed detection signal S4 consisting of a digital electric signal whose frequency changes according to the rotational speed of is outputted to an input terminal of a frequency-voltage converter (hereinafter referred to as an F/V converter) 5, which is a signal converter. The F/V converter 5 receives the speed detection signal S4, converts it into a speed detector @S5 consisting of a voltage signal which is an analog electric signal corresponding thereto, and outputs it to the speed command value calculation circuit 9. On the other hand, 7 is a speed command terminal to which a speed command signal is given by voltage or current, and a speed setting device 8 is connected to this terminal.
input terminal is connected. This speed setter 8 outputs a speed setting signal S8 consisting of an analog electrical signal, for example, a voltage signal, to a speed command value calculation circuit 9 in accordance with a speed command signal applied to an input terminal. 9 is a speed command value calculation circuit;
These input terminals 9a and 9b are connected to the output terminal of the speed setting device 8 and the output terminal of the F/V converter 5, respectively, and the speed setting signal 5ref outputted from each terminal is compared with the speed detection signal Sfb. The deviation value is calculated, and a calculation output signal S9 indicating the calculation result is outputted from the output terminal 9C.

Reference numeral 10 denotes an inverter serving as a variable speed control circuit, one input terminal 10a of which is connected to an output terminal 9C of the speed command value calculation circuit 9. This inverter 10 controls the frequency and voltage of the AC output given to the induction motor 3 from the output terminal 10G in accordance with the calculation output signal S9 inputted from the speed command value calculation circuit 9, and thereby the speed feedback signal Sf
The rotation speed of the induction motor 3 is increased or decreased so that b matches the speed setting signal S ref.

Now, 11 is input terminal 11a, 11b and output terminal 11
The input terminal 11a is connected to the output terminal of the photo encoder 4, the input terminal 11b is connected to the output terminal of the speed setting device 8, and the output terminal 11G is connected to the other input terminal 10b of the inverter 10. It is connected to the.

The electrical configuration of this disconnection detection circuit 11 is shown in detail in FIG. 1 and will be described below with reference to this figure.

Speed setting signal 3 ref is -8 ref at inverting amplifier 12
This is inputted to the addition type comparator 13, which is a comparison means, together with the preset VLO-. Here, the additive n-type comparator 13 is as shown in FIG. 2, 3 ref V LOW (--') + -< O... (1)
2 (Ri is the resistance value of resistor i) When the following condition is satisfied, the output becomes a high level signal, is input to the inverting circuit 14, and outputs a low level. This output signal S14, the negative power supply line voltage -VlG, and the speed feedback signal obtained via the buffer 15 = srb
is input to the input terminal 16a of the additive comparator 16 as comparison means.

A high level output is given to this output terminal 16d when the following condition R161R162R163 is satisfied. If the speed detector 6 is disconnected, the speed feedback signal Qsrb becomes zero, so equation (2) becomes R161R16
2, and the output signal 814 from the inverting circuit 14 is calculated from equation (1), if R131=R132, S ref >
V1. When OW 514=VBE-(4)3 re
When f≦VLO-, 514=Vcc-(5).

Here, VBE is the base-emitter voltage of the transistor 141 of the inversion circuit 14.

As shown in FIG. 2, since the rotating electrical machine does not immediately respond to the speed setting signal S ref for the rotating electrical machine,
Even if the speed setting signal Sref changes from zero to a certain value, the speed feedback signal Sfb lags behind it, so disconnection detection is prohibited at least until the disconnection detection level Vfbo (up to point b in Figure 2). There must be. The circuit for this purpose was shown earlier using the cylindrical comparator 13 (
4) When (5) formula % formula % is satisfied (up to point a in FIG. 2), the terminal 16a receiving the output of the inverting circuit 14 is at VCC, and disconnection detection is prohibited. Therefore, the following relationship can be obtained from equation (3).

R161R162 Assuming that the wire is broken when the speed feedback signal 5fbIfi becomes less than the wire breakage detection level Vfbo (point 0 in Figure 2), then from equation (2), the wire is broken at rVrbo or less.'' is as follows.

Therefore, 814 must be within the range determined by the following equation.

V BE V fb.

R162 (--+--) < 814 <R16"V
ccR161R163R161 If the settings are made as described above, as shown in FIG. becomes a high level, a high level is output to the disconnection detection terminal 11C, and the transistor 171 of the oven collector 17 is turned on.

As explained above, according to the embodiments of the present invention, it is possible to configure a speed detector disconnection detection circuit that detects disconnection of the speed detector only during driving, and in a variable speed control device using speed feedback control. It is now possible to appropriately send a stop command to the speed control section of the device to prevent abnormal operation when the speed detector is disconnected. It has also become possible to use this signal to drive a relay or the like, and use its contacts to drive a brake or the like to forcefully stop the device.

[Effects of the Invention] As explained above, according to the present invention, abnormal operation can be prevented by accurately detecting a disconnection of the speed detector only during driving.

[Brief explanation of drawings]

FIG. 1 is a four-way diagram of the present invention, FIG. 2 is a time chart thereof, and FIG. 3 is a block diagram when the present invention is applied to a variable speed control device having speed feedback. 10.12... Inverting circuit, 11.14... Additive comparator, 13... Buffer circuit, 15... Oven collector circuit.

Claims (1)

[Claims] In an apparatus for controlling a rotating electric machine by comparing a speed setting signal and a speed feedback signal, a speed setting signal detecting means for detecting that the speed setting signal is equal to or higher than a predetermined value, and an output signal of the speed setting signal detecting means The present invention is characterized by comprising a comparison means for comparing the speed feedback signal and a voltage signal corresponding to a predetermined rotation speed and outputting a disconnection detection signal when the speed setting signal is equal to or higher than a predetermined value. Disconnection detection circuit for speed control device.