JPS6289486A - Inverter switching device - Google Patents

Abstract

PURPOSE:To shorten the switching operation time between an inverter and a motor by using a power transistor having current limiting and overcurrent interrupting functions as a switch for opening or closing between the inverter and the motor. CONSTITUTION:An inverter 14 and a motor 15 are opened and closed therebetween by applying ON or OFF control signal to a photocoupler 20 to simultaneously turn ON or OFF transistors 11P, 11N. The operating time is shortened by using a power transistor. When the inertial force of the motor 5 is small, the rotating speed decrease of the motor 5 during the synchronization switching of the motor 15 to other power source is small, the step-out of the synchronization in the synchronization switching time is eliminated, and there is no possibility that an excess current flows between the motor and the other power source.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inverter switching device for switching a motor group between an accelerating inverter and an operating inverter.

B6 Summary of the Invention The present invention provides an inverter switching device that synchronously switches between multiple inverters and motors, by using a power transistor as the main switching element that has current limiting and overcurrent cutting functions between the inverter and the motor, thereby ensuring reliable and easy switching. This allows for synchronous switching.

0. Conventional technology As an inverter operation method for a motor group, there is a method using one acceleration inverter and one driving inverter. The configuration of this system is shown in FIG.

The driving inverter 1 and the acceleration inverter 2 are connected to a large number of motors 3. ~3n is the electromagnetic contactor for opening/closing 4°~4n
It can be opened and closed by #5+ to 5n. Each motor 3
1 to 3n are normally operated by the operating inverter 1, and for acceleration from 8 power to the operating speed, the power is accelerated to the operating frequency of the operating inverter J by the O speed inverter 2, and then when synchronized. Magnetic contactor, 1. ~4
Complementary switching 1 between n and 5+ to 5n.Thus, it is switched to the operating inverter 1 side.

This inverter operation system reduces the operating capacity of the inverter for operation, and reduces the motor starting current by low frequency starting at acceleration in/(-), improving repeated starting capability and reducing mechanical stress. It can be used to drive high-speed spinning machines, etc. for spinning machines.

D. Problems to be Solved by the Invention Conventionally, since electromagnetic contactors are used to switch motor groups, when switching between the acceleration inverter and the driving inverter, the switching time between the magnetic contacts 4 is A difference occurs due to changes over time, etc., and this difference momentarily shuts off the power to the motor/event, and the drop in rotation speed during that time causes a synchronization error, causing an excessive current to be generated in the operating inverter and the concerned Tanabata. was there. Further, the electromagnetic contactor has problems in that the life of the drive coil portion is short, the failure rate increases as the number of motors increases, and frequent maintenance is required.

The present invention has been made in view of the above-mentioned problems, and has a current limiting and overcurrent cutting function between the inverter and the motor to close the circuit between the inverter and the motor. The switch circuit is configured with a power transistor as the main switching element, and the power transistor prevents overcurrent between the inverter and motor by high-speed switching and current limiting, and self-shutoff by the power transistor in case of continued abnormal circulation. I do.

F. Embodiment FIG. 1 is a switch switching circuit diagram showing an embodiment of the present invention, and the electromagnetic contactors 41 to 4D in FIG. 5.

This is a circuit section corresponding to one of the 51st to 5th circuits. Power transistor 11p, 1. Connect diode 1.2p, , 1.2N in series with diode 1.2 for reverse cutting in series with I N n, and dimate 1 for bypass between emitter and collector.
3p and J-3N are connected in parallel to each other and connected between the inverter 14 and the motor 15 to form an open/close switch main circuit. The transistor 1.1 p ld forms a forward current path from the inverter 14 to the motor 15, and the transistor 11N forms a reverse current path from the inverter 14 to the motor 15 when turned on. The diodes 12p and 1.2N are connected to the transistor 11.
p, 11. Compensate for the lack of reverse voltage capacity of N.

Diode 13p, 1.3yt is transistor 1
1. A reverse voltage is transiently applied to p and 1.1 to form a bypass current path.

The drive circuits 16D and 16D are connected to the inverter 14
When the motor 15 is combined with the ml transistor 1.1
The drive circuit 1.6 is representatively shown in drive circuit 1.6 DI. The power transformer 17 is shared by drive circuits 16T) and 16N to obtain AC outputs for the respective control power sources from two secondary windings.

Diode 18 and capacitor 19 constitute a rectifier circuit,
The secondary winding output of the transformer 17 is rectified and smoothed to form a DC control power source. The photocoupler 20 supplies a base current (on control current) from the DC control power source to the power transistor 11N by its on control. A resistor 2J is connected from the photocoupler 20 to the power transistor 11. N゛〈n≦6−
7 electric a. 4, (O 2 □ is interposed between the photocoupler 20 and the base of the power transistor 1.1.N. The base of the power transistor 1.1.N
Zener diode 22 provided in parallel between emitters
A series circuit of resistors 11 and 11 is shown in FIG. Based on the relationship between the base-emitter voltage BE of N and the collector current C, the base-emitter voltage vy as the collector current C of the transistor 11N increases
As nn rises, the Zener diode 22 becomes conductive, reducing the base current and limiting the collector current of the power transistor 11N. The collector current is limited by this base current. The limit is the V of transistor 11N.

As shown in the El-IC characteristic diagram in FIG. 3, the collector current is determined by determining the base current, . limit the saturation current of Next, power transistor 1.1. The thyristor 24 connected in parallel between the base and emitter of H is turned on by supplying an on-gate 'tll current as the voltage of the resistor 23 rises due to an increase in the current flowing through the Zener diode 22, and the collector current of the power transistor 11N increases. In the case of a load abnormality (for example, a motor short-circuit) that increases the current C, the current Tz of the Zener diode 1'' 22 increases.Thus, by turning on the Zener diode 1''22, the base current of the power transistor 11N is cut off, and the power transistor shown in FIG. Its safety 1
Make it work within the production area. In Fig. 4, time t,
~t,i'' indicate the open parameters when energized in the safe operating area.

In a switching device using a closed power transistor as a switching element, when the inverter 14 and the motor 15 are opened,
To close the circuit, the power transistor 11p is closed by applying an on/off control signal to the photocoupler 20.
11 This can be done by having both men and women off at the same time.

Here, the opening/closing between the impark 14 and the motor 15 is caused by the inertial force G1 of the motor J5 as a result of the operation time being significantly shortened by the power transistor compared to a conventional electromagnetic contactor.
Even if 2 is small, there is little decrease in the rotation speed of the motor 5 during synchronous switching of the motor 15 to another power source (for example, an inverter for operation), there is no loss of synchronization within the synchronous switching time, and there is no loss of synchronization between the motor and the other power source. No excessive current will flow through.

Furthermore, when an excessive current is about to flow through the power transistor due to an abnormality in the load motor, the base current of the power transistor is limited and cut off to prevent the overcurrent from being cut off in the operating inverter 1, thereby preventing system down.

In addition, the switching device has no mechanically worn parts, resulting in stable operation that does not change over time even during long-term operation.

In addition, because the switching device has a current limiting function, even if there is a slight synchronization phase shift between the acceleration inverter and the operating inverter, forced synchronization can be achieved while limiting the current, allowing quick and efficient synchronous switching control between the inverters. make it easier.

G. Effects of the Invention As described above, according to the present invention, since the main switching element is a power transistor having a current limiting and overcurrent cutting function as a switch that opens and closes between the inverter and the motor, the switching operation time between the inverter and the motor is shortened. This greatly reduces the phase shift during synchronous switching even for motors with small inertia, and current limiting and overcurrent cutoff ensure quick and reliable synchronized control between inverters and ensure that the system does not go down due to overcurrent. It has the effect of preventing

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a transistor A-vB1! The characteristics diagram, Figure 3 is the transistor's '7 (1 m - C characteristic diagram), Figure 4 is the safe operating area characteristic diagram of the transistor, and Figure 5 is the motor group operation circuit diagram. 1. Inverter for operation, 2. Acceleration inverter, 3
+ * 3n'・Motor, IIm)-1'N'・Power transistor, 1.2I), 12N...Reverse duty diode, 1.3p, 13N...Bypass diode, 14...Inverter, 15...・Motor, t6p,
16N...drive circuit, 17...power transformer, 20
... Photocoupler, 21 ... Base current setting resistor, 2
2... Zener diode, 24... Thyristor.

Claims (1)

[Claims] An inverter switching device for operating a group of motors by synchronously switching between an acceleration inverter and an operation inverter, which has current limiting and overcurrent cutting functions between the inverter and the motor to close the circuit between the inverter and the motor. An inverter switching device characterized by having a switch circuit configured with a power transistor as a main switching element.