JPS6277889A - Motor controlling system - Google Patents

Abstract

PURPOSE:To perform a stabilized speed control on a motor by a method wherein the amount of fluctuation corresponding to the fluctuation of the external environment is calculated by rotating the motor in a test mode based on the initial value data. CONSTITUTION:A DC motor 10 is test-operated by a control part 13 in a test mode based on the initial value data memorized in an initial value memory storage 16. At this time, the value of speed deviation, corresponding to the amount of fluctuation in accordance with the fluctuation of external environment, is calculated and said value is memorized in a deviation value distribution and accumulation part 15. When the test mode is finished, a constant speed mode constant data is calculated from the initial value data obtained from the initial value memory storage 16 and the deviation value obtained from the deviation value distribution and accumulation part 15, and the obtained value is memorized in a motor constant memory storage 17. The DC motor 10 is operated at the fixed speed based on the motor constant read out from the motor constant memory storage 17 in an operation mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a motor control system for a DC motor using a digital servo control system.

[Technical background of the invention and its problems] Conventionally, for example, in an optical character reading device (OCR), a D
A C motor is used. This is because DC motors have relatively high rotational speed and high torque characteristics, and their speed can be easily controlled.

In recent years, digital control methods have been used for servo control of DC motors. In this motor control method, a microprocessor (CPU) is used as a control circuit, and a table of motor constant data corresponding to each speed is stored in advance in a memory. The CPU creates a control variable corresponding to the pulse time width, for example, based on the table in the memory, and provides it to the motor drive circuit. The motor drive circuit is
A drive current corresponding to the pulse time width is supplied to the DC motor.

By the way, in the motor control method as described above, the DC
When performing constant speed control of the motor, the motor is driven based on a constant motor constant at the initial point of transition from an acceleration state to a constant speed state. After this, servo control of the motor is executed by monitoring the speed of the motor. However, if there are significant changes in the external environment of the DC motor, the servo control of the DC motor may not function sufficiently at the initial stage of constant speed ° control. Here, a change in the external environment is, for example, a case where a wide temperature difference occurs and the mechanical load increases, especially at low temperatures. This is considered to be because the motor constants set at the initial stage cannot absorb fluctuations in the external environment of the DC motor.

[Object of the Invention] An object of the present invention is to provide stable speed control in digital servo control of a DC motor, even when there are large fluctuations in the external environment of the DC motor, for example, when transitioning from acceleration to constant speed. The objective is to provide a motor control system that can

[Summary of the Invention] The present invention includes test operation control means for causing a DC motor to perform a test operation based on initial value data of motor constant data in a test mode. The speed deviation value calculation means calculates a speed deviation value of t for a variation corresponding to a change in the external environment during a test operation of the DC motor. The operation data creation means creates motor constant data for the operation mode from the speed deviation value calculated by the speed deviation value calculation means and the initial value data when changing from the test mode to the operation mode. The drive control means is configured to drive the DC motor based on the driving mode motor constant data created by the driving data creating means during the driving mode.

With this motor control method, during test mode,
It is possible to create motor constant data for driving modes that can absorb fluctuations in response to fluctuations in the external environment of the DC motor.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing the configuration of a motor control circuit according to one embodiment. The DC motor IO is equipped with a low-resolution encoder and outputs an encode pulse EP according to the rotation. After shaping and discriminating the encode pulse EP output from the DC motor IO, the shaping/discriminating circuit 11
Output to motor speed detection circuit 12. The motor speed detection circuit 12 counts the interval between encode pulses EP from the shaping/discrimination circuit 11 and detects the rotation speed of the DC motor 10.

The control unit 13 is composed of a microprocessor, and in the test mode calculates a speed deviation value that is a variation in response to changes in the external environment of the DC motor 0, and in the operation mode calculates a speed deviation value that is a variation in accordance with changes in the external environment of the DC motor 0. In the operation mode, it calculates a speed deviation value that is a variation in accordance with changes in the external environment of the DC motor 0. Create motor constant data based on the speed deviation value. The control unit 13 outputs a drive pulse DP created based on motor constant data to the motor drive circuit 14. The motor drive circuit 14 supplies the DC motor 10 with a drive current according to the drive pulse DP.

The speed deviation value calculated by the control unit 13 is stored in a memory (RAM) that is the deviation value distribution storage unit 15. The initial value is stored in advance in an initial value memory (ROM) 1B. The motor constant data created by the control unit 13 is
Stored in motor constant memory (RAM) [7]. The clock generation circuit 18 outputs lock pulses necessary for each operation to the motor speed detection circuit 12 and the control section 13.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 to 4. First, the control unit 13 executes a test mode,
Performs the necessary motor constant data setting operation in normal operation mode. The control unit 13 causes the DC-E-Ita 1O to perform a test operation based on the initial value data stored in the initial value memory 1G in advance. When the DC motor IO is driven to rotate,
An encode pulse EP is output from the rotary encoder as described above.

The motor speed detection circuit 12 counts the pulse interval of the encode pulse EP by counting clock pulses from the clock generation circuit 18.

Thereby, the speed ■ of the DC motor IO can be detected. The detected velocity V is expressed, for example, by a curve 30 as shown in FIG. Here, in FIG. 3, since the speed data V is determined based on the count number of clock pulses, the increase/decrease relationship between the speed data V and the actual speed 30 is reversed.

Now, as shown in FIG. 3, when the DC motor 10 starts rotating at time To, the next drive pulse DP
Let the pulse time width of PTW be PTW. The control unit 13 monitors the speed V of the DC motor 1o and controls the DC motor 10 when the speed exceeds a predetermined monitoring speed (Vi-ΔVi).
It is determined that the speed of has reached a constant speed (time Tc in Fig. 3).
).

Next, the control unit 13 sets a predetermined constant speed V of the DC motor 10.
For i, a velocity variation ΔVj corresponding to a variation in the external environment as shown in FIG. 3 is determined. Here, the initial value memory 16 stores a table of initial value data as shown in FIG. 4(a).

That is, for a predetermined constant speed Vt of the DC motor IO, the initial value data is data corresponding to the pulse time width PTiw of the drive pulse DP. The control unit I3 controls the speed variation Δ
A pulse time width ΔPTw corresponding to Vj is calculated from the following equation (1).

ΔPTw-K(G・ΔVj+M−Δm+J・Δn)...(1) Here, K, G, M, and J are constants, and 6m is rvj
−v (j−1) J , Δn is [ΣΔVjJ.

After calculating ΔPTw from equation (1), the control unit 13 determines the distribution at the sampling points in the test mode. That is, the control unit 13 controls the same ΔPf in the test mode.
The frequency N in the case of w is counted, and the distribution state as shown in FIG. 2 is stored in the deviation value distribution storage section 15. At this time,
At each sampling point in the test mode, initial value data PTiw is used, rPT i w + ΔP T w
J to the next sampling point (PTw
).

In this way, when the test mode ends, the control unit 13 extracts Δ with the maximum frequency N from the deviation value distribution storage unit 15.
Find PTiw. The control unit 13 includes a deviation value distribution storage unit I
From ΔPTiw from 5 and initial value data PTiw from initial value memory 16, constant speed motor constant data "ΔPT
Calculate i w+PT i wJ. This constant speed motor constant data [ΔPTiw+PTiwJ is stored in the motor constant memory 17 in a state as shown in FIG. 4(b).

Next, when switching from the test mode to the driving mode, the control unit 13 drives the DC motor 10 to rotate. In this case, the control unit 13 reads constant speed motor constant data obtained during the test mode from the motor constant memory L7, and operates the DC motor 10 at a constant speed Vi based on this data. That is, the control unit 13 outputs a drive pulse DP having a pulse time width corresponding to the constant speed motor constant data [ΔPT iW+PT t WJ to the motor drive circuit 14. The motor drive circuit 14 supplies the DC motor 10 with a drive current according to the pulse width of the drive pulse DP. Therefore, even if fluctuations occur in the external environment, the DC motor lO has constant speed motor constant data "Δ
Since it is driven based on PTiw+PTiwJ, it rotates stably at a constant speed.

[Effects of the Invention] As detailed above, according to the present invention, in digital servo control of a DC motor, by rotating based on initial value data in the test mode, fluctuations corresponding to fluctuations in the external environment can be reduced. You can ask for it. Therefore, even if there are large fluctuations in the external environment of the DC motor during a transition from acceleration to constant speed, for example, stable speed control can be performed by controlling the drive of the DC motor using the initial value data and the fluctuation. It is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of a motor control circuit according to an embodiment of the present invention, FIGS. 2 and 3 are characteristic diagrams for explaining the operation of the embodiment, and FIG. 4(a), (b)
are diagrams for explaining the operation of the same embodiment.
a) is a diagram showing an example of the storage contents of the initial value memory;
b) is a diagram showing an example of the stored contents of a motor constant memory. DESCRIPTION OF SYMBOLS 10... DC motor, 12... Motor speed detection circuit, 13... Control part, 14... Motor drive circuit, 15
... Deviation value distribution storage unit, 16... Initial value memory, 1
7...Motor constant memory. Applicant's agent Patent attorney Takehiko Suzue Figure 4

Claims (1)

[Claims] In a motor control method in which the speed of a DC motor is digitally controlled based on motor constant data stored in advance, the DC motor is tested based on initial value data of the motor constant data in a test mode. a test operation control means for driving the DC motor; a speed deviation value calculation means for calculating a speed deviation value corresponding to a variation in accordance with changes in the external environment during the test operation of the DC motor; and a change from the test mode to the operation mode. operation data creation means for creating motor constant data for an operation mode from the speed deviation value calculated by the speed deviation value calculation means and the initial value data;
A motor control system comprising: drive control means for driving the DC motor based on motor constant data for driving mode created by the driving data creating means during the driving mode.