JPH02202390A - Motor speed control method - Google Patents

Abstract

PURPOSE:To enable control of a high speed motor by fixing an encoder to the motor and varying the timing of a drive signal following to the variation of motor speed and corresponding to the number of cycle of an encoder signal. CONSTITUTION:When a motor 30 rotates with low speed, a CPU33 starts operation every time when one cycle of an encoder 31 signal rises. Upon finish of operation of about 0.1msec, a drive signal DS is produced and the rotation of the motor 30 is controlled through a motor drive circuit 32. When the motor 30 rotates with high speed, the CPU33 starts operation for every two cycle rising of the encoder 31 signal and provides the drive signal DS to the motor drive circuit 32 upon finish of operation of about 0.1msec. By such arrangement, high speed rotation control of the motor 30 can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed control force θ of a motor whose rotational speed is variable.

[Conventional technology]

In a conventional speed control system for a DC or AC motor, for example, as shown in FIG. 3, an encoder 31 is attached to a motor 30, and pulse signals from the encoder 31 are input to a CPU 33, which controls the motor drive circuit. The drive signal DS was output to the terminal 32. Then, the rotation speed of the motor 30 is controlled based on this drive signal DS. The CPU 33 receives a drive signal D.
Based on the encoder signal from the encoder 31, the current rotation speed of the motor 30 is compared with a predetermined rotation speed, and a drive signal is output to the drive circuit 32 so that the motor 30 is driven at the predetermined rotation speed.

[Problem to be solved by the invention]

The calculation time of the drive signal of the CPU is (1,1m5
As shown in FIG. 4, an interrupt signal is input to the CPU at the rising edge P of one cycle of the encoder signal, and this input causes the CPU to stop outputting the drive signal DS to the drive circuit 32. After the calculation is completed, a drive signal based on the calculation result is sent to the drive circuit 32.
I was trying to output it to .

However, as the motor 30 becomes faster, the time for one cycle of the encoder signal becomes shorter, and even at this time, C
Since PU requires a certain amount of calculation time, the drive signal DS
The amount of time the motor is outputting becomes shorter, making it difficult to control the motor's rotational speed at high speeds.

In view of this point, an object of the present invention is to provide a high-speed control method for a motor that is capable of controlling a motor at high speed.

[Means to solve the problem]

Therefore, the present invention attaches an encoder to a motor whose speed is variably controlled, inputs this encoder signal to a control section, controls the drive circuit of the remoter with a drive signal from this control section, and responds to changes in motor speed. Following this, the calculation timing of the drive signal is changed in accordance with the number of cycles of the encoder signal.

[Effect]

When an encoder is attached to a variable speed motor and the interval between rising edges of each cycle of this encoder signal becomes short, the CPU skips a predetermined number of rising edges of the encoder signal and generates an interrupt at the rising edge of each cycle to output the drive signal. is calculated, and after the calculation is completed, a drive signal that changes the frequency or voltage is output to the drive circuit. This allows the motor to output a drive signal even at high speeds.
Time is secured and the motor can be controlled at high speed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, when the variable speed motor 30 is at a low speed, an interrupt is sent to the CPU at each rising edge of one cycle of the encoder signal, and this interrupt signal causes the CPU to
The PU33 starts calculation, and the CPU lowers the drive signal DS to approximately 0.
．． The calculation is performed for 1 m5ec, and after the calculation is completed, the drive signal DS is output to control the rotation of the motor 30 (FIG. 1a).

When the motor 30 becomes faster, as shown in FIG. 1b, calculation starts at the rising edge of every two cycles of the encoder signal, and after completing the calculation for 0,1 m5ec, the drive signal DS is sent to the drive circuit 32. Output to. That is, the rising edge after the end of one cycle of the two cycles of the encoder signal is skipped, and the calculation is started at the rising edge of the next cycle. In this way, the time during which the drive signal DS is outputted can be
That is, even if the duty ratio of the ON time of the drive signal increases and the motor rotates at high speed, the rotation can be controlled.

In the embodiment shown in FIG. 1b, the CPU is interrupted at the rising edge of every two cycles of the encoder signal to calculate the drive signal, but if the motor 30 becomes faster, it may be possible to calculate the drive signal every three or four cycles. Thus, the ON time of the drive signal DS is ensured to be the required time.

The driving of the CPU 33 will be explained in detail with reference to the broach yard in FIG.

In response to the start signal, the CPU starts operating and the CPU 33
In step Sl), it is determined whether or not any interrupt signal has occurred during the drive control process of the encoder. If it is related to the calculation timing, the flag is cleared (step S3), the encoder data is read, and the current signal of the motor 30 is determined. The rotation speed N is read (step S4). Next, the current state of the motor 30 (J:.

It is determined whether the rotational speed N is high or low by comparing it with the reference rotational speed (step S5), and when the rotational speed is high, the calculation timing at high speed, for example, the calculation timing at the rising edge of every two cycles of the encoder signal, is set. (For example, set the calculation timing at the rising edge of one cycle of the encoder signal in step S6.S.
7), step S8 to execute the calculation according to this set value.
), set the calculation timing flag in step S9).
Repeat this action.

〔Effect of the invention〕

Since the present invention is configured as described above, it has the effect that the motor can be controlled at high speed.

[Brief explanation of the drawing]

Fig. 1a is an operation timing chart of the encoder signal and motor drive signal at low speed, Fig. 1b is an operation timing chart of the encoder signal and motor drive signal at high speed, Fig. 2 is an operation flowchart of the CPU, and Fig. 3 4 is a diagram of a motor control system, and FIG. 4 is an operation timing chart of encoder signals and motor drive signals for conventional motor control. 30...Motor, 31...Encoder, 32...
Drive circuit, 33...CPU. Applicant's agent Yasushi Ishikawa Engraving of Figure 2 drawing (no changes to the content) ((]) (b) Figure 1 procedure ShinrIj Original date of 1989

Claims (1)

[Claims] An encoder is attached to the motor whose speed is variable controlled, and this encoder signal is input to the control unit.The drive signal from this control unit controls the motor drive circuit, and the drive signal is calculated by following changes in the motor speed. A method for controlling the speed of a motor, characterized in that the timing is changed in accordance with the number of cycles of the encoder signal.