JPS5889094A - Speed controller for motor - Google Patents

Abstract

PURPOSE:To arbitrarily set the rotating speed of a motor externally by arbitrarily regulating and applying the amplitude of the output waveform of a voltage waveform generator to the drive unit of the motor. CONSTITUTION:A frequency/voltage converter 8 converts the frequency of the signal obtained by converting the rotating speed of a motor 2 into a voltage and a voltage waveform generator 28 generates the voltage waveform of the prescribed frequency, and can regulate the mid potential of the voltage waveform externally. These outputs are applied to a comparator 44, which outputs a speed control pulse of the pulse width in response to the output voltage level of the converter 8. Waveform converters 46A-46C interrupt the output of a drive signal generator 14 in response to the speed control pulse and supplies it to the motor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor speed @ control device, and in particular to a pulse width modulation (PWM) type speed control suitable for speed control of polyphase motors used in video tape recorders, turntables, etc. Regarding equipment.

FIG. 1 shows the basic configuration of a three-phase motor drive control device. The motor 2 and frequency generator 4 are interlocked,
The frequency generator 4 generates an alternating current signal (frequency signal) having a frequency proportional to the rotational speed of the motor 2. This frequency signal is converted into pulses by the program counter 6 and input to the frequency-voltage conversion circuit 8. The frequency-voltage conversion circuit 8 is composed of a sawtooth wave generation circuit IO and a sample hold circuit 12, and the pulse is given to the sawtooth wave generation circuit 10 as a trigger signal and at the same time, given to the sample hold circuit 12 as a sample pulse. It will be done.

The sawtooth wave generation circuit IO sequentially generates a sawtooth wave having a peak value proportional to the synchronization in synchronization with the pulse, while the sample hold circuit 12 generates the sawtooth wave generated by the sawtooth wave generation circuit 10. The high value is sequentially updated and held, and the holding voltage is output. Since this voltage output is proportional to the peak value of the sawtooth wave or the period, it is a frequency-voltage conversion output. These sawtooth wave generation circuits 10
The sawtooth wave output and the voltage output of the sample and hold circuit 12 are given to a drive angle control signal generation circuit 14. This drive angle @ control signal generation circuit 14 generates a drive angle control signal having a different phase by a predetermined angle obtained by combining these signals, and this drive angle control signal is transmitted to the drive unit 16 by a drive provided in the phase silver. After the circuits 16A, 16B, and 16C have undergone processing such as increase in radiation, each coil 2A, 2B, and 2C of the motor 2
The driving angle control is given individually as human power. Further, the output of the sample and hold circuit 12 is given to each drive circuit 16A, j6B, and 16c as a drive control input, and the drive angle control input given to each coil 2A, 2B, and 2C is the output voltage of the sample and hold circuit 12. It is designed to be controlled.

In the case of a drive control device configured in this way, if it is attempted to change the frequency-voltage conversion circuit, it is necessary to add a DC amplifier to the output section of the frequency-voltage conversion circuit.
Furthermore, in consideration of speed control, it is necessary for the DC amplifier to perform an amplification operation centered on the control DC potential point. Therefore, a method has been proposed in which the amplitude of the voltage waveform used to form speed control pulses can be adjusted externally by pulse width modulation, thereby increasing the overall gain of the control system without using a DC amplifier.

An object of the present invention is to provide a motor speed control device that allows the midpoint potential of the voltage waveform to be set externally and to set a desired speed.

This invention includes a frequency-voltage conversion circuit that converts the frequency obtained by converting the rotational speed of a motor into a voltage, and a voltage waveform with a constant frequency that can be adjusted externally. The output voltage of the frequency-voltage conversion circuit is applied to the voltage waveform generator configured, and the output voltage of the frequency-voltage conversion circuit is applied together with the output voltage of the voltage waveform generator. It is characterized in that it is configured to include a comparator formed by width modulation.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the motor speed control device of the present invention. In this embodiment, the same parts as in FIG. 1 are given the same reference numerals. In the figure, the held output of the sample-and-hold circuit 12 and its generation point level are divided by a voltage dividing circuit 20 of a drive signal generating circuit 14 according to the phase setting. In this case, one! 1 Synchronize tooth wave input 3
For example, in the case of a three-phase system, the voltage from the generation point level to the peak value is divided into three equal parts to form a phase shift of every 120°. This voltage output is transmitted to the phase shift circuit 22 together with the tM tooth wave output generated by the saw tooth wave generating circuit 10.
A phase shift signal having a phase shift of every 120 degrees is formed based on a comparison between the sample hold output and the divided voltage output, and is input to the drive angle control signal forming circuit 24. The drive angle control signal forming circuit 24 forms a drive angle control signal having a phase shift of 120 degrees based on the phase shift signal input (1).The drive angle control signal generates a predetermined drive force with a constant phase shift. This drive angle control signal is given as a rectangular wave pulse having a pulse width of 1 (1) necessary to obtain the following. After this drive angle control signal is subjected to control processing in the speed control section 26, it is sent to each drive circuit 16A, 16B of the drive section 16.

16C.

A voltage waveform generator that generates a voltage waveform such as a sawtooth wave, a triangular wave, or an exponential wave whose frequency is higher than the output frequency of the sawtooth wave generation circuit 10 while the rise of the voltage waveform is given to the speed @ opening 26 as a time function. A circuit 28 is provided. That is, a reference oscillation circuit 30 provided in this voltage waveform generation circuit 28 oscillates a reference voltage waveform of the voltage waveform, and this reference voltage waveform is generated by an amplitude setting circuit configured with a variable resistor 32 in this embodiment. At 34, the amplitude is externally adjusted and set arbitrarily.

The voltage waveform whose amplitude has been set in this manner is applied via a capacitor 36 to a midpoint potential setting circuit 40 composed of a variable resistor 38, and the midpoint potential Vo is adjusted externally according to the set speed. It is configurable. The voltage waveform output whose amplitude and midpoint potential have been set by the amplitude setting circuit 34 and the midpoint potential setting circuit 40 is given to the comparator 44 together with the frequency-voltage conversion output via the buffer 1 circuit 42. - The voltage output is subjected to Tehalus width modulation according to the voltage waveform and converted into a switching pulse having a pulse width corresponding to the voltage level.

This pulse is inputted to AND circuits 46A, 46B, and 46C as waveform conversion circuits provided in each phase along with the drive angle control signal 1, and the logical product of both signals produces an intermittent signal, or a continuous signal depending on the amplitude setting. The signal is converted into a pulse signal and manually inputted to the drive section 16. In this case, each coil 2A, 2B, 2C of the motor 2 has a power supply voltage Vcc.
is applied via drive circuits 16A, 16B, and 16C.

Figures 3 through 6 show the operating waveforms of this speed l4ai device. In FIG. 3, A shows the output waveform of the frequency generator 4, B shows its conversion output obtained by the program counter 6, and C shows the output waveform of the #A toothed sequential raw circuit IO. In C, ■ρh, , Vph, and ν
phs is the output voltage of the frequency-voltage conversion circuit 8, ■ is t
Generation point level of M toothed wave, vl, ■2 is voltage divider circuit 2
The divided voltage level at 0 is shown. D and E indicate phase-shifted signals formed by the phase-shifting circuit 22 based on the voltage divided outputs, and the # edges of each pulse of D and E are 120', respectively.
The phase transition is as follows, and each rear twill portion has an angle of 360°. F, G and H are drive angle control signal forming circuit 2
The drive angle control signal obtained by combining the D and E phase shift signals in 4 is shown, and it can be seen that each pulse has a shape of 360° divided into three equal parts.

In FIG. 4, ■ indicates the output waveform of the voltage waveform generation circuit 28, and Vph, , Vph2, and ■ρha are superimposed displays of vph, , vph, and V9hs of FIG. 3c. J is the sawtooth wave shown in ■ and the voltage ■ρ
By inputting h, , Vph2 and Vph, ' comparator 4
4 indicates a speed control pulse formed by pulse width modulation. This pulse is given to AND circuits 46A, 46B and 46C together with drive angle control signals shown as F', G' and H', and each drive angle control signal is logically ANDed with the speed control pulse and shown as K, L and M. Converted into an intermittent or continuous signal.

FIG. 5 shows the voltage waveform generation circuit 28 by operating the malleable resistor 32.
A warning is displayed when the amplitude of the output waveform is set to 1/2 of that in the case of FIG. Bi is its sawtooth wave, Vph, , Vph,
and Vph3 similarly indicate the frequency-voltage conversion output.Jl corresponds to J in Figure 4, and as is clear from the comparison of the two, the pulse width of the speed control pulse can be halved by manipulating the amplitude. It turns out that it consists of As a result, in FIG. 4, the drive angle control signal waveforms of L and M are changed as shown in ', L' and M'.

FIG. 6 shows the voltage waveform generation circuit 28 by operating the variable resistor 38.
The midpoint potential of the output waveform of #! This shows the case where the midpoint potential in the case of FIG. 5 is changed by -ΔV. Reference numeral 11 indicates the sawtooth wave, and V Plot , V ph2 and phs similarly indicate the same wave number-voltage conversion output.

J# corresponds to J' in FIG. 4, and as is clear from a comparison of the two, it can be seen that the pulse width of the speed control pulse can be changed to 3/4 by controlling the amplitude. As a result, Figure 4 shows '
, L', and M' drive angle control signal waveforms are K#, L'
and M'.

In this way, the pulse width of the speed control pulse can be changed and applied to the drive unit 16 of the motor 2 by arbitrarily setting the voltage and the amplitude of the output waveform of the waveform generation circuit 28 from the outside, and the voltage waveform By changing the midpoint potential of , the control comparison level in the comparator 44 can be changed. As a result, the speed of the motor 2 can be set arbitrarily; for example, by setting the center point at the center point potential Vo, it is extremely easy to set the speed according to the tape speed of the VTR or the rotation speed of the turntable, etc. can be done. In particular, when controlling the speed of a polyphase motor, in order to change the overall gain according to the rotation speed, the configuration is such that the speed can be set by changing the midpoint potential at any amplitude of the voltage waveform. It is possible to perform stable speed control.

In addition, although the case of a three-phase motor was explained in the embodiment, the present invention can also be applied to a polyphase motor with three or more phases, and for the sake of explanation, the drive angle tl! Although the 111 signal is set to have a phase shift of 120 degrees, in the case of three phases, the phase shift is 60 degrees (it goes without saying that this can be similarly applied even when configured using No. 2).

As explained above, according to the present invention, the rotation speed can be arbitrarily set by adjusting and setting the midpoint potential of the voltage waveform from the outside.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a general drive control device for a three-phase motor, Fig. 182 is a block diagram showing an embodiment of the motor drive control device of the present invention, Figs. 3 A to H, and Figs. Figure 5 I' to M' and Figure 6 I# to M'
is an explanatory diagram showing its operating waveform. 2... Motor, 8... Frequency-voltage replacement circuit, 26
. . . Equipment Wllll control unit, 28 . . . Voltage waveform generation circuit, 44 . . . Comparator. Figure 1 4 Do 8 Written amendment to the proceedings of Party B March 1, 1980 Commissioner of the Japan Patent Office Shima 1) Haruki Tono 1, Display of the case 1987 Patent Application No. 187180 2, Name of the invention Motor speed control Apparatus 3, relationship with the case of the person making the amendment Patent Applicant Address 21 Saiin Mizosaki-cho, Ukyo-ku, Kyoto Name: ROHM Co., Ltd. Representative: Ken Sato Part 4, Agent: 167 Address: 3-2 Amanuma, Suginami-ku, Tokyo No. 2-703, Ogikubo Kangyo Building, 7th floor [11 "Drive control device" on page 11, lines 10 and 11 of the specification has been corrected to "speed control device." (2) “In the specification, page 11, lines 11 to 14,
FIG. 3A is an explanatory diagram. ” is corrected as follows. ``Figures 3, 4, 5, and 6 are explanatory diagrams showing the operating waveforms.''

Claims (1)

[Claims] It consists of a frequency-voltage conversion circuit that converts the frequency of the signal obtained by converting the rotational speed of the motor into voltage, and a voltage waveform of a constant frequency that is generated and the midpoint potential of that voltage waveform can be adjusted externally. A voltage waveform generator is provided with the output voltage of the frequency-voltage conversion circuit together with the output voltage of the voltage waveform generator, and pulse-width modulates the control pulse at a speed of a pulse width according to the output voltage level of the frequency-voltage conversion circuit. A speed control device for a motor, characterized in that it is configured to include a comparison formed by: