JPH0365093A - Temperature control method for motor - Google Patents

Abstract

PURPOSE:To operate a servo motor efficiently by making use of the change of the winding resistance value of the coil of a servo motor so as to detect the temperature of the coil of the servo motor, and putting a wait time before the next start based on the detection results or controlling the number of revolutions and the current value. CONSTITUTION:The winding resistance value of a servo motor 5 changes according to the temperature. If the servo motor 5 is driven by a small amount, a current detection circuit 6 detects the current value. The output of the current detection circuit 6 is input into a counter 7. muCPU 1 detects the coil temperature of the servo motor 5 by the table value (temperature data) of ROM3 based on the output of the counter 7. muCPU 1 outputs a control signal to an I/O port 2 according to the detection results. The I/O port 2 drives the servo motor 5 through a driver circuit 4. Hereby, the wait time, the number of revolutions, and the current value are controlled, whereby the servo motor 5 can be utilized effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of controlling the temperature of a servo motor used in a spacing motor of a printer's carriage.

(Prior Art) Conventionally, motors have been used in various electronic devices based on their performance and characteristics, such as spacing motors for helad carriages in serial printers (hereinafter referred to as "space motors"). .

Normally, the space motor is used to space the print head during printing, but when continuous printing is performed over a long period of time, the space motor's winding (
(coil) temperature rises, and this temperature rise may cause seizure or performance deterioration of the space motor.

Therefore, in order to prevent such a situation, for example, a device with a high rating is used or a heat sink is installed. In addition, a heat-sensitive element such as a thermistor is installed inside the space motor to detect the temperature of the space motor, and the average driving cycle of the space motor is lengthened by controlling based on the detected temperature.

(Problem to be Solved by the Invention) However, in the temperature control method for the motor with the above configuration, both of using a motor with a large rating and attaching a heat sink to the motor effectively utilize the motor efficiently. Moreover, when a heat-sensitive element is provided, an expensive element is required, which increases the cost of the printer device.

The present invention solves the problems of the conventional motor temperature control method described above, eliminates the need for a high-rated motor, eliminates the need for a heat sink or heat-sensitive element, and reduces costs by operating the motor efficiently. It is an object of the present invention to provide a method for controlling the temperature of a motor.

(Means for Solving the Problems) For this purpose, in the motor temperature control method of the present invention, the motor is driven for a minute time when the motor stops, and the value of the current flowing through the motor at that time is detected. Since the detected current value varies depending on the temperature of the motor windings, the temperature of the motor is detected from the magnitude of the current value.

Therefore, the current value is converted into a count value, temperature data corresponding to the count value is read from the table, and the driving load of the motor is controlled according to the temperature data.

(Operation) According to the present invention, when the motor stops as described above,
The motor is driven for a short period of time, and the value of the current flowing through the motor at that time is detected, thereby detecting the temperature of the motor.

That is, as shown in FIG. 4, the motor drive signal a is output for a short period of time to drive the motor, and the current flowing through the motor at that time is detected. The detected current value varies depending on the temperature of the motor windings, for example bt, bs, bs in Fig. 4.
The transition is as follows. So, set this to slice level b4
By comparing with CI+C! Obtain a count value such as +C3.

Then, temperature data corresponding to the count value is read from a table stored in the memory, and the driving load of the motor is controlled according to the temperature data.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram of a servo motor drive control circuit in which the motor temperature control method of the present invention is adopted, and FIG. 3 is a circuit diagram of a servo motor driver and a current detection circuit.

In the figure, 1 is a μCPU, and μCPU 1 connects to I10 port 2 and program RO via a pass line.
Connected to M3. Further, the servo motor driver circuit 4 drives the servo motor 5 using an input signal from the I10 port 2.

A current detection circuit 6 is connected to the servo motor 5, and the current detection circuit 6 detects the current flowing through the servo motor 5. Its output terminal is connected to the counter 7, and the output terminal of the counter 7 is connected to the μCPU 1 described above. Based on the output signal (count value) from the counter 7, the μCPU 1 uses R (the table value of the IM 3 (
The coil temperature of the servo motor 5 is detected from the temperature data).

Next, the means for detecting the coil temperature of the servo motor 5 will be explained.

The winding resistance of the servo motor 5 increases as its temperature rises, and the relationship between the two is as follows.

R, -((234,5+θ, )/(234,5+θ.

)]×R0... (1) R8: Winding resistance value when the temperature of the coil of the servo motor 5 rises θX: Winding temperature θ when the temperature of the coil of the servo motor 5 rises. Two base rate temperature (25°) Ro: Winding resistance value of the coil of the servo motor 5 at the reference temperature (25°) By detecting the winding resistance value of the coil of the servo motor 5 from this relationship, the servo motor 5 It is possible to detect the temperature rise of the coil.

Then, in order to detect the winding resistance value of the coil of the servo motor 5, the value of the current flowing through the coil is detected.

FIG. 3 is a circuit diagram of the servo motor driver and current detection circuit of FIG. 2.

In the figure, 11 to 14 are I10 port 2 (Figure 2)
The transistor 15 is operated by the signal output from the logic elements 11 to 14 depending on the level of the output of the logic elements 11 to 14.
19 are turned on and off, and the servo motor 5 is driven.

In order to detect the current flowing through the servo motor 5, a current detection resistor R+ is inserted. This resistance R
3 is sufficiently smaller than the winding resistance value of the coil of the servo motor 5, and is approximately 0.5Ω.

A comparator 20 is provided to detect the potential difference between both ends of the resistor Ro, and a resistor R□R2 is connected to determine the reference potential (slice level) of the comparator 20.

In the comparator 20, the potential difference across the resistor R1 is compared with a reference potential, and the output signal is sent to the counter 7.
(Figure 2).

Next, the operation of the motor temperature control method of the present invention will be explained with reference to FIGS. 1, 4, and 5.

FIG. 1 is a flow chart of the motor temperature control method of the present invention, FIG. 4 is a time chart when a drive signal is applied to the servo motor, and FIG. 5 is an equivalent circuit of the servo motor.

In the motor temperature control method of the present invention, the value of the current flowing through the servo motor is detected, and the detected current value is converted into a count value with a different pulse length depending on the magnitude of the current value.

That is, as shown in FIG. 4, the servo motor drive signal a
is applied to the servo motor driver 4 from the μCPU 1 (FIG. 2) through the I10 port 2 for a certain minute period of time, thereby driving the servo motor 5 by a minute amount. This is done when the servo motor 5 is stopped.

At this time, as shown in FIG.
The waveforms of the current flowing through the servo motor 5 are inputted to the terminal (FIG. 3).

Here, FIG. 5 is an equivalent circuit of a servo motor.

The value i of the current flowing through the equivalent circuit of the servo motor 5 is i'' (E/R) (1-e-'''') --(2)
becomes.

R: Winding resistance value of the servo motor coil L: Inductance of the servo motor coil E: Voltage between the terminals of the servo motor (voltage of transistors 16 to 19 from the potential vM on the emitter side of transistors 16 and 18 in Figure 3) drop, wiring voltage drop, etc.> From equations (1) and (2) above, the winding current flowing through the coil of the servo motor 5 changes depending on the winding resistance value R, and the winding resistance value R Since it changes depending on the temperature of the wire, the temperature rise of the servo motor 5 can be detected by the change in the winding current.

That is, as shown in FIG.
-) The input waveform of the terminal changes as shown by the solid line indicated by a square when the servo motor 5 is at a high temperature, as shown by the dashed line indicated by b8 when the temperature is medium, and as shown by the broken line indicated by a square when the servo motor 5 is at a low temperature. If this input waveform is cut at the input level (slice level) b4 of the (+) terminal of the comparator 20, it can be converted into pulses with different pulse lengths as shown by the output waveforms cl and cmC3 of the comparator 20.

As described above, the operation will be described when the servo motor 5 is driven by a minute amount, the current value is detected, and the wait time is immediately applied to the servo motor 5.

Steps ■~■ Apply the servo motor drive signal a to the servo motor 5 for a very short time.

Step ■ The output signal of the comparator 20 is sent to the counter 7.
(Figure 2) and the counted value is sent to the μCPU.
Read as 1 input signal.

Step ■ μCPU 1 is set to ROM according to the read value.
Read the table value (temperature data) from 3.

Step ■■ Compare the temperature data with some reference temperature data, and if the value is higher than the reference temperature data, a wait time is set.

Step ■ After the wait time ends, determine the direction of the minute drive performed for the previous temperature detection.

Step ■ [Phase] If the previous minute drive direction is the forward direction, the next minute drive direction is the reverse direction,
If the previous minute drive direction is the reverse direction, the next minute drive direction is set as the forward direction. Steps ① to [phase] are repeated until the temperature data of the coil of the servo motor 5 becomes lower than the reference temperature data.

Step ■ When the temperature data of the coil of the servo motor 5 becomes lower than the reference temperature data, the next driving operation is performed.

Note that instead of using the wait time, it is also possible to control the rotational speed and current value of the servo motor 5 using temperature data.

As explained above, in this embodiment, the winding temperature of the coil of the servo motor 5 is detected, and depending on the winding temperature,
The servo motor 5 is driven at an optimum duty.

Further, the minute drive performed to detect the winding temperature of the coil of the servo motor 5 is detected by a slit sensor or the like, and feedback is applied to μCPt11. Therefore, when the servo motor 5 is used as a spacing motor for a spacing carriage of a printer, problems such as misregistration will not occur.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, when the motor stops, the motor is driven for a minute time, the current value flowing through the motor at that time is detected, and the magnitude of the detected current value is counted. To detect the motor temperature by converting it into a value, if you use the μCPU's built-in timer as a counter, a single comparator can detect the temperature of the servo motor coil using changes in the winding resistance value of the servo motor coil. can do. Based on the detection result, the servo motor can be driven by setting a wait time before the next activation or by controlling the rotation speed and current value, so that the servo motor can be used efficiently.

As a result, there is no need to use a motor with a large rating, a heat-sensitive element, or a heat sink, and the cost of the printer device can be reduced.

[Brief explanation of drawings]

Figure 1 is a flowchart of the motor temperature control method of the present invention, Figure 2 is a block diagram of a servo motor drive control circuit in which the motor temperature control method of the present invention is adopted, and Figure 3 is a servo motor driver and current detection circuit. The circuit diagram, Figure 4 is the time chart when the drive signal is given to the servo motor,
FIG. 5 is a diagram showing an equivalent circuit of a servo motor. l...μCPU, 2...I10 boat, 3...
・Program ROM, 4... Servo motor driver circuit, 5... Servo motor, 6... Current detection circuit,
7... Counter, 11, 12.13.14... Logic element, 15.16.17.18.19... Transistor, 20... Comparator.

Claims (1)

[Claims] (a) Drive the motor for a minute time, (b) Detect the current value flowing through the motor at that time, (b) Count the detected current value with different pulse lengths depending on the magnitude of the current value. (c) reading temperature data corresponding to the count value from a table; and (d) controlling the driving load of the motor according to the temperature data.