JPH0557832B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides input of a positive polarity speed signal of a voltage corresponding to the rotational speed during clockwise rotation, and input of a positive polarity speed signal of a voltage corresponding to the rotational speed during counterclockwise rotation. This is a rotational speed signal converter that inputs negative polarity speed signals of corresponding voltages, converts these speed signals into signals, and outputs a rotational speed detection signal, and is capable of quickly suppressing vibrations immediately before rotation stops. The present invention relates to a device that outputs a rotational speed detection signal suitable as a servo signal.

[Prior art] This type of rotational speed signal converter in the past is as follows:
It is constructed as shown in FIG.

In the figure, 1 is an F/V converter (frequency/
A rotation signal from a rotating body to be detected, such as a DC brushless motor, is introduced into its input terminal (voltage converter). This rotation signal is a pulse-like detection signal from a magnetic encoder or the like, and the pulse interval becomes smaller as the rotation speed increases, regardless of the rotation direction.
The F/V converter 1 converts the rotation signal into an analog voltage V1 (Fig. 4a) proportional to the rotation speed, and outputs the voltage V1 to a voltage follower 2 and an operational amplifier (operational amplifier). )3 to the inverting input terminal. The output voltage of the voltage follower 2 is input to the voltage follower 5 through the first analog switch 4, while the voltage inverted and amplified by the operational amplifier 3 is input to the voltage follower 5 through the second analog switch 6. The amplifier of voltage follower 2 is "1", and the amplification factor of operational amplifier 3 is "-1".
, and the output of the voltage follower 5 becomes the rotational speed detection signal V0.

The first and second analog switches 4 and 6 have their control signals (indicated by broken lines in the figure) at "H" level.
, respectively. The forward and reverse rotation detection circuit 7 is designed to open and close the analog switches 4 and 6 based on the rotation direction signal, and the input rotation direction signal is clockwise CW as shown in FIG. 4b. This is a digital signal that becomes "H" when rotating and "L" when rotating counterclockwise CCW. This rotation direction signal is 2
The control signal passes through two inverters 8 and 9 to become a control signal for the first analog switch 4, and passes through one inverter 10 to become a control signal for the second analog switch 6.
Close analog switch 4 and turn counterclockwise CCW.
The second analog switch 6 is closed during rotation.

Therefore, the rotational speed signal converter configured in this way can change the signal from the first and second analog switches 4 and 6 by selectively switching them depending on the rotation direction. A rotational speed detection signal V0 whose polarity changes depending on the rotational direction is directly output.

[Problems to be Solved by the Invention] By the way, just before the rotating body to be detected is stopped, vibrations may occur due to delays in the control system, and the rotational direction signal may repeatedly change in short cycles. be. In such a case, since the conventional rotational speed signal converter obtains the rotational speed detection signal directly from the analog switches 4 and 6, the rotational direction signal changes repeatedly in short cycles, which inevitably causes The rotational speed detection signal changes repeatedly in short cycles.

However, outputting such a repeatedly changing rotation speed detection signal just before the rotation stops causes a problem in that when the signal is used for rotation speed control, vibrations do not subside and control becomes unstable. It was hot.

This invention solves these problems.

[Means for Solving the Problems] The rotation speed signal converter according to the present invention has a first switch that supplies a speed signal of a voltage according to the rotation speed when the rotation direction of the rotating body is clockwise. and a second switch for supplying an inverted speed signal with the polarity of the speed signal reversed when the rotation direction is counterclockwise, and a second switch for charging and discharging the speed signal supplied by the first switch. a first charging/discharging circuit for charging and discharging the inverted speed signal supplied by the second switch; Equipped with an addition circuit that adds the voltages of the signals,
The present invention is characterized in that the signal added by this adding circuit is output as a rotational speed detection signal.

[Function] According to the present invention, when vibration occurs immediately before the rotating body stops rotating and the rotating direction of the rotating body changes frequently, the speed signal, The inverted speed signals are alternately supplied and charged by the first and second charge/discharge circuits, respectively.

In this case, the adding circuit adds signals whose absolute values are substantially the same but whose polarities are different from each other, so that it is possible to stabilize the rotation detection signal that is the result of the addition.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Note that the same parts as those in the conventional example described above are given the same reference numerals, and the explanation thereof will be omitted.

Charge/discharge circuits 11 and 12 having the same time constant are connected to the rear stages of the first and second analog switches 4 and 6. The charging/discharging circuit 11 consists of a capacitor C1 and a resistor R1 connected in parallel, while the charging/discharging circuit 12 consists of a capacitor C2 and a resistor R2 connected in parallel. The downstream stage of the charging/discharging circuit 11 is connected to the adding circuit 14 through the voltage follower 13 , and similarly, the downstream stage of the charging/discharging circuit 12 is connected to the adding circuit 14 through the voltage follower 15 . R3 is the input resistance of the voltage follower 13, R4 is the voltage follower 15
This is the input resistance of , and these have the same resistance value. In the adder circuit 14, R7 and R8 are input resistances, R9 is a feedback resistance, and R10 is a grounding resistance, and the input resistances R7 and R8 have the same resistance value.

In addition, the control signals for analog switches 4 and 6 are as follows:
They are output from AND circuits 16 and 17, respectively.
The AND circuit 16 is configured such that the rotation direction signal is directly inputted to one input terminal thereof, and the sampling pulse is inputted to the other input terminal thereof. The AND circuit 17 inputs the rotation direction signal inverted by the inverter 18 to one input terminal thereof, and
A sampling pulse is input to the other input terminal. The sampling pulse is applied to the capacitors C1 and C in the charging and discharging circuits 11 and 12.
This is a clock pulse with a constant period whose period is sufficiently shorter than the second discharge time.

Next, the operation will be explained.

Each time a sampling pulse with a sufficiently short predetermined interval is input, the AND circuit 1
6 and 17 intermittently close either analog switch 4 or 6. That is, the first analog switch 4 is intermittently closed during clockwise CW rotation, and the second analog switch 6 is intermittently closed during counterclockwise CCW rotation.

During the former rotation clockwise CW, the output voltage of the voltage follower 2 is intermittently charged to the capacitor C1 of the charging/discharging circuit 11 through the first analog switch 4. Since the period of the sampling pulse is sufficiently short compared to the discharge time of the capacitor C1, a voltage corresponding to the voltage V1 is stored in the capacitor C1, and this voltage is input to the adder circuit 14 through the voltage follower 13. be done. At this time, since the second analog switch 6 remains open for a predetermined period of time, the capacitor C2 of the charge/discharge circuit 12 downstream of the analog switch 6 remains open.
is in a completely discharged state and has no effect on the adder circuit 14. Therefore, this clockwise direction
When the CW rotates, a rotation speed detection signal V0 having a magnitude corresponding to the rotation speed and having a positive polarity is output, as in the case of the conventional example described above.

On the other hand, during the latter counterclockwise CCW rotation,
The voltage inverted and amplified by operational amplifier 3 is
The capacitor C2 of the charge/discharge circuit 12 is intermittently charged through the analog switch 6. Since the period of the sampling pulse is sufficiently short compared to the discharge time of the capacitor C2, a voltage corresponding to the voltage V1 is stored in the capacitor C2, and this voltage is input to the adder circuit 14 through the voltage follower 15. be done. At this time, since the first analog switch 4 remains open for a predetermined period of time, the capacitor C1 of the charging/discharging circuit 11 downstream of the analog switch 4 is in a completely discharged state. The adder circuit 14 is not affected. Therefore, during this counterclockwise rotation CCW, a rotational speed detection signal V0 having a magnitude corresponding to the rotational speed and having a negative polarity is output, as in the case of the conventional example described above.

By the way, just before the rotating body to be detected is stopped, vibrations may occur due to delays in the control system, and the rotational direction signal may repeatedly change in short cycles, as in the case of the conventional example described above. be. In such a case, when the cycle of repeated changes in the rotational direction signal becomes sufficiently short, that is, at time _t0 in FIG. 2c, the rotational speed detection signal V
Forcibly stabilize 0 to "0".

That is, when the period of change in the rotational direction signal becomes sufficiently short, the analog switches 4 and 6 will close alternately in short periods, and therefore the capacitors C1 and C2 of the charging and discharging circuits 11 and 12 will be completely closed. They will store voltages of similar magnitude and opposite polarity. These voltages are added by the adding circuit 14, and the rotational speed detection signal V0 outputted from the adding circuit 14 becomes "0". The relationship between the rotation speed detection signal V0, the output voltage Va of the voltage follower 13, and the output voltage Vb of the voltage follower 15 is expressed by the following equation.

V0={(Va/R7)+(-Vb/R8)}R9 In this way, forcibly setting the rotational speed detection signal V0 to "0" means that the rotational speed detection signal V0
This is extremely advantageous when used for controlling the rotational speed, and vibrations just before the rotation stops can be quickly suppressed to stabilize the control.

Note that as a means for outputting control signals for opening and closing the first and second analog switches 4 and 6, it is also possible to employ the same forward and reverse rotation detection circuit 7 as in the conventional example described above, and sampling Pulsing is not necessary.

[Effects of the Invention] According to the invention described above, when vibration occurs immediately before the rotating body stops rotating and the rotating direction of the rotating body changes frequently, the , a speed signal, and an inverted speed signal are alternately supplied and charged by the first and second charge/discharge circuits, respectively.

Therefore, when such vibration occurs, the addition circuit adds signals whose absolute values are approximately the same but whose polarities are different, so that the rotation detection signal that is the result of the addition is stabilized. As a result, vibrations immediately before the rotation stops can be quickly suppressed, and the control can be made stable.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a time chart for explaining its operation. FIG. 3 is a circuit diagram of a conventional rotational speed signal converter, and FIG. 4 is a time chart for explaining its operation. 1...F/V converter, 2...Voltage follower,
3... Inverting amplifier, 4, 6... Analog switch, 11, 12... Charging/discharging circuit, 13... Voltage follower, 14... Adding circuit, 15... Voltage follower,
V0...Rotation speed detection signal.

Claims (1)

[Claims] 1. A speed signal of a voltage corresponding to the rotation speed and a rotation direction signal representing the forward and reverse rotation directions are input, and the speed signal and this speed signal are determined based on the rotation direction signal. A rotation speed signal converter that outputs a rotation speed detection signal that simultaneously represents forward and reverse rotation directions and rotation speeds by selecting an inverted speed signal obtained by reversing the polarity of the rotating body. If it is around,
A first supplying a speed signal of a voltage according to the rotation speed.
a second switch for supplying an inverted speed signal with the polarity of the speed signal reversed when the direction of rotation is counterclockwise; and a charging switch for the speed signal supplied by the first switch. A first charging and discharging circuit that performs discharging; a second charging and discharging circuit that performs charging and discharging of the inversion speed signal supplied by the second switch; and charging and discharging the first and second charging and discharging circuits, respectively. 1. A rotational speed signal converter comprising: an addition circuit that adds the voltages of the signals, and outputs the signal added by the addition circuit as a rotational speed detection signal.