JPS588669B2 - DC output reversible device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC output reversible device capable of controlling forward and reverse rotation of an auxiliary motor, etc. of a rolling line in a steel mill.

Figure 1 shows a basic DC output reversible device that uses a thyristor to reversibly control a DC motor, in which 1 is an AC power supply, 2 and 3 are AC side terminals connected to AC power supply 1, and DC side terminals. 4 is a three-phase bridge-connected positive and reverse thyristor switch that is reversibly connected with mutually opposite polarities, and 4 is a series coil 5 connected between the DC output terminals of both thyristor switches 2 and 3.
The armature of the DC motor is connected in series with the DC motor, and 6 is the shunt field winding of the DC motor.

In this circuit, the direction of the current in the armature 4 of the motor is switched by controlling the firing of both thyristor switches 2 and 3 alternately to perform forward/reverse control.This method is used in shunt-wound motors. No hindrance will occur.

However, in motors for auxiliary equipment used in steel mill rolling lines, which operate frequently in reversible mode and require maximum torque at start-up, the motors have a field winding in series with the armature. Series-wound motors or even compound-wound motors that supply a constant field independently from the outside are used.

When the armature 4' of a series-wound or compound-wound electric machine is reversibly controlled in the above-described manner as shown in FIG. 2, the series-wound field winding 7 is The flowing current is in the opposite direction, and the magnetic flux of the series-wound field is in the opposite direction.Series-wound motors cannot be switched between forward and reverse directions, and compound-wound motors have a series-wound field and a shunt-wound field. In the case of forward rotation, it is a summation, and in the case of reverse rotation, it is a differential, which causes fluctuations in torque characteristics and makes it impossible to perform satisfactory control.

This invention takes the above points into consideration, and enables reversible operation control of a series-wound or compound-wound motor by always passing current in the same direction through the series-wound field winding. The present invention will now be described in detail with reference to drawings showing one embodiment thereof.

In FIG. 3, 8 is an AC power supply, 9 and 10 are three-phase bridge-connected positive and reverse thyristor switches, 11, Reference numeral 12 denotes first and second diodes connected in series with the same polarity as both the thyristor switches 9 and 10 between both ends of the thyristor switches 9 and 10 connected in series, and 13 a connection between the thyristor switches 9 and 10. an armature of a series-wound or compound-wound motor connected in series with a series coil 14 between the point and the connection point of both diodes 11 and 12; 15 is a shunt field winding when the motor is compound-wound;
16 is a series field winding connected between both ends of the diodes 11 and 12 connected in series.

When the motor is rotated in the forward direction, the forward direction thyristor switch 9 is turned on, and the path of the forward direction thyristor switch 9, the series field winding 16, the second diode 12, the series coil 14, and the armature 13 of the motor is turned on. When the electric current flows, the motor rotates in the forward direction6. Also, when the motor is to rotate in the reverse direction, the reverse direction thyristor switch 10 is turned on, and the reverse direction thyristor switch 10, the armature 13 of the motor, the series coil 14, and the first Current flows through the path of the diode 11 and the series-wound field winding 16, and the current flows through the armature 13 of the motor in the opposite direction to that in the case of forward rotation, causing the motor to rotate in the opposite direction.

In this case, current flows through the series field winding 16 in the same direction indicated by the arrow both during forward and reverse rotation, allowing reversible control of the series or compound motor.

As described above, according to the DC output reversible device of the present invention,
In a DC output reversible device that performs reversible control of a DC motor using a thyristor switch, the circuit is Accordingly, it is possible to provide a DC output reversible device for controlling a series-wound or compound-wound motor at low cost without providing a complicated device to the motor.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an example of a DC output reversible device, Fig. 2 is a circuit diagram when the DC output reversible device shown in Fig. 1 is applied to a series-wound or compound-wound motor, and Fig. 3 is a DC output reversible device according to the present invention. FIG. 2 is a circuit diagram of one embodiment of a reversible output device. 8... AC power supply, 9, 10... Positive and reverse direction thyristor switch, 11, 12... First and second diodes,
13...Armature of a series-wound or compound-wound motor.

Claims (1)

[Claims] 1 Three-phase bridge-connected positive and reverse thyristor switches whose AC side terminals are connected to an AC power supply are connected in series, and first and second diodes are connected between both ends of the series-connected thyristor switches. The thyristor switches are connected in series with the same polarity, and the armature of a series-wound or compound-wound motor is connected between the connection point of the two thyristor switches and the connection point of the two diodes, and a series-wound field is connected between both ends of the series-connected diodes. A DC output reversible device characterized by connected windings.