JPS6154899A - Controller of motor - Google Patents

Abstract

PURPOSE:To provide a function of soft starting, holding the constant rotation and continuously controlling a motor with a simple construction by connecting a semiconductor control element in series with the winding of the motor, and connecting a capacitor in parallel with the winding. CONSTITUTION:The winding L of a motor and a triac T are connected in series, and a capacitor C is further connected in parallel with the winding L. When a load is applied during the operation of the motor, a positive feedback is applied equivalently due to the capacitor to hold at the constant rotation, and the motor can be softly started similarly when the no load is applied. Further, the trigger phase of the triac T can be continuously varied by regulating a variable resistor Rv to continuously control.

Description

[Detailed description of the invention] Technical fields> The present invention relates to a motor control device.

<Prior art> Conventionally, AC motors (including universal motors, which are series-wound motors that can be used for both AC and DC) by directly applying commercial AC
To control the triac, as shown in Figure 3, the trigger point of the triac T connected in series with the motor winding is changed by a variable resistor Rv connected to the gate of this triac 'F. was.

In this case, as the variable resistance RV changes, the triac T
In this case, conduction starts from the peak point of the power supply voltage, which makes soft start impossible.

Furthermore, as shown in Fig. 4, by connecting a capacitor C1 between the gate of the triac T and the electrode T1, the trigger point of the triac T is delayed by a delay circuit consisting of the capacitor C1 and the resistor R1, and the software It becomes possible to start.

However, this circuit has the disadvantage that constant speed control is difficult, the rotational speed changes depending on the load, and the rotational speed decreases as the load increases.

Also, a half-wave energization or full-wave energization method using Cyrisk is used, but in this case, the speed is controlled in three stages, not continuous control, and furthermore, there is no soft start or constant rotation maintenance function.

In this way, in the conventional control device of this type, (i
) Soft start, (11) Constant rotation maintenance, (iii)
Problem 1 was that it was difficult to satisfy all requirements for continuous control or multi-step control.

On the other hand, in order to perform the above-mentioned soft start, constant rotation maintenance, and continuous control, phase control by computer is required.
is used, but in this case 1lilJ f'Jll
The disadvantage was that the equipment was expensive.

<Object of the Invention> The present invention has been made in view of the above-mentioned item 1n, and its object is to provide a motor control device with a simple configuration and functions of soft start, constant rotation maintenance, and continuous control. It is to provide.

<Structure of the Invention> The present invention is characterized by comprising a semiconductor control element connected in series with the windings of the motor, and a capacitor connected in parallel with the windings.

<Example> An embodiment of the present invention will be described below.

FIG. 1 shows the circuit configuration of a motor control device.

For example, a motor winding and a triac T are connected in series between a terminal t1 and a terminal t2, to which a commercial type tA (not shown) of AClooV is connected. A variable resistor RV and a resistor R2 are connected in series between the gate of the triac T and a resistor R1 is connected between the gate of the triac T and the electrode TI of the triac T. Furthermore, a capacitor C is connected in parallel with the motor windings. The motor having the above-mentioned windings is, for example, a universal motor.

The operation of the above circuit will be explained.

The angular velocity corresponding to the frequency of the commercial power supply connected between terminals B and t2 is ω(-2πf, f = 6011z in Kansai)
, f = 50 Hz in the Kanto region), then the impedance Z between the connection points α and β, which is a parallel circuit of the motor winding and the capacitor C, is obtained. Then, if the voltage between terminal B and t2 is ■, and the lightning current I, then I=V/Z
Therefore, if the voltage (2) is constant, the current (2) is proportional to the reciprocal of the impedance Z (1/Z). It should be noted that since the triac T operates in an on/off manner, the voltage ■ does not remain in constant phase.

Now, if you apply a load to the motor while it is operating, the inductance L will effectively decrease and the load will increase. ffi compensation, but without the capacitance C, this load compensation is I/j
It is only for ωL. However, since there is a capacitance C,
As is clear from equation (1), the term 1-ω2LC is added, and positive feedback is applied isometrically. As a result,
Constant rotation can be maintained.

Further, when there is no load, the current flowing through the winding due to the gate trigger of the triac T is reduced by an amount corresponding to the term 1-ω2LC, so that a soft start can be similarly realized. Furthermore, by adjusting the variable resistor Rv, the trigger phase of the triac T can be changed continuously, making continuous control possible. Or this variable +
By using lV anti-RV as a multi-stage resistance switching system,
Nearly continuous multi-step control can be achieved.

FIG. 2 shows a case where a small-capacity capacitor C1 is connected in parallel with the resistor R1, and has the same characteristics as described above.

As described above, by connecting the capacitor C in parallel with the motor windings, it is possible to further remove overcurrent and provide a safety maintenance function by detecting abnormal torque.

<Effects of the Invention> As explained above, in the present invention, since the capacitor is connected in parallel with the motor winding, ff1
With a flexible configuration, it is possible to provide functions such as motor soft start, constant rotation maintenance, continuous control or multi-step control, and safety maintenance through overcurrent removal and abnormal torque detection.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing an embodiment of the present invention, and FIGS. 3 and 4 are circuit diagrams showing a conventional example. L...Winding 1゛...Triac 2 C...Capacitor

Claims (1)

[Claims] (1) A motor control device comprising: a semiconductor control element connected in series with a winding of a motor; and a capacitor connected in parallel with the winding.