JPS6271489A - Drive controller for dc motor - Google Patents

Abstract

PURPOSE:To decide the abnormality of revolution quickly and precisely, and to prevent the damage of a DC motor by stopping condition to the DC motor when currents more than a reference value flow through the DC motor for a specified period or more. CONSTITUTION:Currents flowing through a DC motor 1 are detected by a detecting means 2. A comparison means 3 is connected to the detecting means 2. The comparison means 3 compares currents detected by the detecting means 2 with a reference value. A control means 4 stops conduction to the DC motor 1 when currents detected by the detecting means 2 flow for a specified period in quantity more than the reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention relates to a DC motor drive 1IIJ used for, for example, an electric fan with variable rotation speed, and in particular to a protection mechanism for abnormal rotation thereof. It is.

(b) Conventional technology As a protection mechanism in a drive control device for a DC motor,
Disclosed in Japanese Unexamined Patent Publication No. 56-62035, when the back electromotive force of the DC motor drops below a predetermined level for a predetermined period of time or more, the power supply to the DC motor is stopped to protect the locked state. Or, JP-A-57-779
A device that detects the stoppage of rotation of a motor by using a capacitor, as disclosed in Japanese Patent No. 68, is well known. Furthermore, there are those that use temperature sensing elements such as bimetal, and those that detect capacitance changes such as guards in fan 8a machines (Japanese Patent Publication No. 54-43).
684, Utility Model Publication No. 56-48952).

(c) Problems to be solved by the invention However, in devices that utilize back electromotive force, the back electromotive force and b may vary due to variations in the motor windings, flux, etc., making it difficult to make accurate judgments. However, with capacitors, errors in rotational speed detection may occur due to changes in characteristics due to aging or temperature, such as loss of capacitor capacity, and there are concerns about long-term use.

In addition, devices that use a humidity sensing element have a long operating time, and may vary depending on the ambient temperature.Moreover, devices that detect capacitance changes may cause malfunctions or may come in contact with the guard when being carried. However, there were problems such as the rotation stopped and the circuit configuration became complicated.

This invention was made in view of the above-mentioned circumstances, and it is possible to quickly and accurately judge when an abnormal rotation occurs, and to prevent the DC motor from being damaged (stopped) when an abnormality occurs. The aim is to provide equipment.

(d) Means for Solving Problems The configuration of the present invention includes a detection means for detecting the current flowing in a DC motor, and a comparison between the detected current and a reference value, and when the detected current is equal to or higher than the reference value. A DC motor characterized by comprising a comparison means for outputting an output signal in a certain case, and a control means for stopping energization to the DC type vJ11 when the output signal is continuously input for a certain period or more. It is a drive control device.

In FIG. 1, (1) is a DC motor, (21 is a detection means for detecting the current flowing through the DC motor 111 (1), and (3
) is a comparison means connected to the detection means (a), and (4) is a control means whose input end is connected to the comparison means (3) and whose output end is connected to the DC motor (1).

(e) Function Since the present invention is configured as described above, the detection means ('2I) detects the current flowing in the DC power supply circuit (1), and the comparison means (3) compares the detected current with the reference. Compare with value.

When the detected current exceeds a reference value and flows for a certain period of time or more, the control means (4) acts to stop energizing the DC motor (1).

(f) Examples Examples of the present invention will be described below in detail with reference to the drawings, but the invention is not limited to the following examples.

2 to 4 are examples in which the DC motor drive control device (Δ) of the present invention is used in an electric fan (B), in which the comparison means (3) and the control means (/1) are It is constructed using a computer.

The electric fan (B) consists of a printed circuit board in which the drive control device (A) is embedded (a base (8) containing a sword, and a support (9) that stands on the base (8). , and a fan part opening υ provided at the upper end of the support column (9) via a neck piece V.The fan part Ov has a guard surface that can be divided into front and rear parts, and a guard surface inside the fan part Ov, as shown in FIG. Out-rotor type DC motor (motor) fixed to the neckpiece (1)
) and the air blower 111 provided on the boss portion (14) fixed to the rotor a3! (151) and a spinner (16) for fixing the boss part (2).

Next, the drive control device <A) will be explained with reference to FIGS. 4 and 5.

The control means (4) is composed of a microcomputer On, a drive circuit, and an output transistor circuit composed of a plurality of transistors. The microcomputer 07) detects rotor position detection signals (U INPLIT), (V INPLIT>, (
W INPUT>, the corresponding 'F1 motor rotation signals <LILJ 0UT) and (VLI
0LIT), (WU 0UT), (UD OU
T>, (VD 0LJT), (WD 0UT) are output to the drive circuit mark a.

The drive circuit is output 1 - motor rotation signal (UU 0UT) inverted to transistor circuit, (WD 0U
T) and rotates the DC motor (1). Each of the above rotor position detection signals (LJ INPUT)
, (V INP(JT), (W INPUT) and their respective motor rotation signals @(uu our-r>, (
VUOU-r), (WU0LJT)
, (()D 0LJT) , Mv'D 0
FIG. 5 shows the relationship between the timings of LJT) and WU OUT. The comparison means (3) is composed of a comparator color and a resistor &4+(c) for generating a reference value. A resistor (E) connected between the output transistor circuit and the ground is the detection means (2). (c)
is a DC power supply circuit.

The microcomputer a7I corresponds to the air volume setting,
Rotation control signal is input. When the DC motor (1) starts rotating, the current flowing through the DC motor (1) (hereinafter referred to as motor current) flows through the resistor (G), and as a result, a voltage corresponding to the current is generated across the resistor (C). vd/fi occurs. The motor current is detected by this voltage Vd.

The comparator (c) compares the voltage d with the reference voltage Vref, which is a reference value that is divided between the resistor 1 and the resistor 1 and the voltage inside the resistor. When the voltage Vd exceeds the reference voltage Vref, that is, the DC electric motor tl! +11 is locked or overloaded and the detected current is above the reference value,
The output signal (current signal) So of the comparator (to) is “L”
°becomes a rubel. When the DC motor (1) is rotating normally, the motor current is below the reference value, and therefore the current signal So is at the current level. FIG. 6 shows the relationship among the motor current, the standard value, the current signal SO, and the rotational state of the DC motor.

Here, the microcomputer (17) receives the current signal So at the H11 or “'L” level and controls the DC motor (17).
) to determine whether to stop energizing. The operation of the microcomputer at this time will be explained with reference to FIGS. 7 and 8.

The microcomputer program consists of a main routine shown in FIG. 7 and an internal interrupt routine shown in FIG.

First, in the main routine, after the power is turned on, the inside of the microcomputer +177 is initialized (step 100). Next, it is determined whether the rotation control input is an ON signal (step 101).

If the rotation control input is OFF, direct current! ! 'eI
Performs the stop processing of ll(1) (step 102)
, the process returns to step 101 and the ON signal is input.

When the ON signal is input, the DC motor (1) is rotated (step 103), and step 10
Return to 1.

Next, the internal interrupt routine is started every two fixed times ti+sec by a timer (not shown) provided inside the microcomputer a7), regardless of the main routine, and is executed by interrupting the execution of the main routine. Ru.

When the internal interrupt routine is started, the current signal is “
Determine whether it is input at the LIT level (
Step 104). If the current signal is at °H” level,
Step 105: Clear the period counter that counts how long the LII level state of the current signal continues.
), prepare for the next count and start the main routine.
Return to Chin. However, if the current signal is at the L'' level, the count contents of the period counter are compared with the reference value T set in the memory during initialization in the main routine (step 10G), and if nt<T, the period counter is incremented (step 107). ), return to the main routine.In step 106, nt≧T
If so, it is assumed that the abnormal current has flowed for a certain period of time or more, and a process is performed to stop energizing the DC motor (1) (step 108), and after stopping the rotation, the process returns to step 100 of the main routine. To summarize the above operation, as shown in FIG.
II level, during which steps 104, 106, and 107 are executed and the contents of the period counter are incremented, the number of υ11 times becomes n1 times and 0.
In the case of 2 times (nl>n2), n 1t <TSn
2 t < T, the stop processing (step 108) of the DC motor (1) is not performed, and the period counter is cleared when the current signal So reaches the ``'' toll bell. However, if the current signal So is Standard 1i
If the 11 L $ level continues for more than the period of flT and the number of interruptions becomes n:t (na > ni > n2) during that period, n3t≧T and the DC motor (1) is stopped ( Step 108) is executed. Therefore, even if the motor current becomes abnormal instantaneously or for a short period of time, the DC motor (1) will not be stopped.

Note that the reference value T and [, which determines the interrupt activation cycle], are set so as not to damage the DC motor (1) in the event of an abnormality.

(G) Effects of the Invention According to this invention, since abnormality is detected by detecting the motor current, abnormal rotation of the DC motor can be reliably detected without malfunction, and the power supply to the DC motor and the output transistor circuit is stopped. Thus, a DC motor drive #71 control device that can prevent burnout is obtained. Furthermore, since the motor current is detected, it operates as a protection mechanism not only in the event of an abnormality in the DC motor but also in the event of a failure of the output transistor. Furthermore, since the DC motor is not stopped unless an abnormal current flows for a certain period of time as a condition for stopping the DC motor, there is no malfunction due to rush current when starting the DC motor.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 and FIG.
Figure 4 is the same electrical circuit diagram of the embodiment, and Figure 5 is a timing diagram showing the relationship between the rotor position detection signal and rotation signal stop. Fig. 6 is an explanatory diagram showing the interrelationship between the motor current, current signal, and the state of the DC motor, and Figs. 7 and 8 are
The figures are a flowchart of a main routine and a flowchart of an internal interrupt routine, explaining the program of the microcomputer in the embodiment, and FIG. 9 is an internal v1-included timing chart showing the correlation between current signals and internal interrupt timing. (1)...DC motor, (21...detection means, (3)...comparison means, (4)...
...control means. Figure 7 Figure 8

Claims (1)

[Claims] 1. a detection means for detecting the current flowing through the DC motor; a comparison means for comparing the detected current with a reference value and outputting an output signal when the detected current is greater than or equal to the reference value; 1. A drive control device for a DC motor, comprising: control means for stopping energization to the DC motor when an input continues for a certain period of time or more.