JPH033615A - Automatic restarting of inverter after release from momentary service interruption - Google Patents

Abstract

PURPOSE:To automatically perform re-starting pull-in working after release current by setting the re-starting pull-in working at the time of the generation of momentary service interruption exceeding the momentary service interruption resistance of an inverter or at the time of the release current, forcibly to come to the maximum frequency of running frequency. CONSTITUTION:When service interruption exceeding no service interruption resistance of an inverter 14 is generated, then running frequency is kept stored in a storage circuit in the inverter 14 at the time of service interruption, and is repulled in from frequency stored at the time of release current. When service interruption exceeding the momentary service interruption resistance of the inverter 14 is generated, then the input of signal 28 from an OFF-delay timer is provided, and by an AND condition with the signal of a keep relay 22 for displaying that the relay 22 is under operation, a contact 26 is closed, and maximum frequency setting command 26 is cast into a momentary service interruption/commercial change-over option card 20. As a result, at the time of the release current, the inverter 14 starts re-starting pull-in working with commercial change-over working.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is designed to prevent failures such as overvoltage and overcurrent when power is restored after an instantaneous power outage (hereinafter referred to as "momentary power outage") occurs in an inverter. The present invention relates to a method for automatically restarting an inverter after a momentary power failure and for automatically performing a restart operation after a momentary power failure without causing any trouble.

[Conventional technology]

Conventionally, when an instantaneous power failure that does not exceed the instantaneous power failure tolerance occurs while a motor is being operated by an inverter, the restart operation is memorized using the amount of electricity stored in the inverter's DC intermediate circuit or the capacitor of the control power supply. The operating frequency at the time of the instantaneous power failure is stored in the circuit, and when the power is restored, restart operation is automatically performed from the stored operating frequency. In addition, if an instantaneous power outage that exceeds the instantaneous power outage tolerance occurs, the amount of electricity stored in the capacitor will be discharged and the memory of the operating frequency at the time of the instantaneous power outage will be lost, so the system will restart from zero as in a normal start. A method is adopted in which a restart operation is performed.

[Problem to be solved by the invention]

However, according to the above-mentioned method for restarting the inverter after a momentary power failure and power recovery, the instantaneous power failure tolerance is reduced. ! When the power is restored in the event of an instantaneous power outage exceeding 100%, the motor will start from zero, so if the motor is rotating due to inertia, an overvoltage trip will occur.

Therefore, to avoid such overvoltage trips,
It is necessary to wait for the motor to stop before starting it, but if the load has a large flywheel effect GD', the free-run stop time will be long, and if the machine is intended for continuous operation or continuous operation is desired. This method could not be applied to systems where the method is used because it would deteriorate productivity or cause problems in production.

Therefore, the purpose of the present invention is to provide a system that enables continuous operation even with a large load of GD2 when an instantaneous power outage that exceeds the inverter's instantaneous power outage tolerance occurs, and that enables prompt restart after the instantaneous power outage without causing failures such as overvoltage or overcurrent. An object of the present invention is to provide a method for automatically restarting an inverter after power is restored from a momentary power failure, which can automatically perform a reloading operation.

[Means to solve the problem]

The method for automatically restarting an inverter after instantaneous power failure recovery according to the present invention is a method for automatically restarting an inverter after a momentary power failure, when an instantaneous power failure that exceeds the instantaneous power failure tolerance of the inverter occurs in a system that operates a motor via an inverter. determine that
It is characterized by forcibly setting the restart operation at the time of power restoration to the highest operating frequency.

[For production]

According to the method for automatically restarting an inverter after instantaneous power failure recovery according to the present invention, when an instantaneous power failure that exceeds the instantaneous power failure tolerance of the inverter occurs, a keep relay is installed to remember that the motor was in operation at the time of the instantaneous power failure. By ANDing the output signal of the inverter and the time-up signal that is output when the off-delay timer, which is set to the instantaneous power failure tolerance time of the inverter, times up due to the occurrence of a long instantaneous power failure, the instantaneous power failure tolerance of the inverter is exceeded. It determines that a power outage has occurred, and when the power is restored, the inverter restart operation is forcibly set to the highest operating frequency. In other words, the operation is similar to the inverter operation switching mode from commercial power supply. Therefore, operation can be continued without any problems.

〔Example〕

Next, an embodiment of the method for automatically restarting an inverter after a momentary power failure and recovery according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of the main parts of a system for operating an electric motor via an inverter, showing an embodiment of the automatic restart method after power recovery from instantaneous inverter power failure of the present invention. Reference numeral 10 denotes a power supply, and the power supply 1o drives and controls an electric motor 18 by an inverter 14 via a breaker 12.A switch 16 for inputting an operation command is also connected to the inverter 14, and a switch 16 is connected for instantaneous power outage/commercial switching. An option card 20 is added.
A normally open contact 30 is connected to the commercial switching option code 2o. The normally open contact 3o is operated by a signal from the AND circuit 24, and gives the highest frequency command 26 to the instantaneous power failure/commercial switching option card 20 when closed. AND circuit 24
are off-delay time-up signal 28 and keep relay 2
2 output signal is input. In addition, keep relay 22
A switch 16 for inputting an operation command is connected to.

At the start of normal operation, the device configured as described above starts from zero by closing switch 16 and inputting an operation command to inverter 14 and keep relay 22.

If an instantaneous power outage that does not exceed the instantaneous power outage tolerance of the inverter 14 occurs, the operating frequency at the time of the instantaneous power outage is stored in a memory circuit that operates using a capacitor in an intermediate circuit (not shown) in the inverter 14 as a power source, and when the power is restored, The inverter 14 is restarted from the stored frequency.

In addition, at this time, the off-delay time-up signal 28
is not occurring, the AND condition with the output signal of the keep relay 22 is not established, and the AND circuit 24 is connected to the normally open contact 3.
Does not output a signal for closing operation for 0.

When an instantaneous power failure that exceeds the instantaneous power failure tolerance of the inverter 14 occurs, an off-delay timer (not shown) that has been set in advance as the instantaneous power failure tolerance time outputs an off-delay time up signal 28.
occurs. Additionally, when a momentary power outage occurs, the keep relay 22 remembers that it was in operation, and when power is restored, the keep relay 22 outputs an output signal indicating that it was in operation when the momentary power outage occurred. do. This keep relay 22 makes it possible to distinguish between a case where normal operation is started and a case where an instantaneous power outage occurs during operation and then power is restored. AN
Since the D circuit 24 satisfies the AND condition of the off-delay time-up signal 28 and the output signal of the keep relay 22, the AND circuit 24 closes the normally open contact 30 and sets the maximum frequency setting command 26 to the instantaneous power failure/commercial switching option. card 2
Insert into 0. Momentary power outage/commercial switching option card 2
0 sets the inverter 14 to the highest frequency 1. That is, the restart operation is automatically started in the commercial switching operation, and operation is continued without overvoltage tripping.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the method for automatically restarting an inverter after power recovery from a momentary power failure of the present invention, there is no need to use a momentary power failure/commercial switching option card that can be easily attached to the inverter body, a keep relay, etc. By adding a simple relay sequence, it is possible to automatically restart the system immediately after a momentary power outage without causing failures such as overvoltage or overcurrent, which can reduce productivity. It is possible to perform continuous operation in the event of a momentary power outage without disrupting production.

Therefore, it can be applied to machines intended for continuous operation under a load with a relatively large flywheel effect GD2, and to systems where continuous operation is desired, and such systems can be easily constructed.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of essential parts of a system for operating an electric motor via an inverter, showing an embodiment of the instantaneous inverter power failure recovery tf & automatic restart method according to the present invention. FIo 1 10... Power supply 12... Breaker 14.
...Inverter 16...Switch 18...Electric motor 20...Momentary power failure/commercial switching option card 22...
Keep relay 24...AND circuit 26...Maximum frequency setting command 28...Off delay time-up signal 30...Normally open contact ＼ ear ζ No. 87-

Claims (1)

[Claims] (1) In a system that operates an electric motor via an inverter, if an instantaneous power outage that exceeds the instantaneous power outage tolerance of the inverter occurs, it is determined that the instantaneous power outage exceeds the instantaneous power outage tolerance, and the system restarts when power is restored. A method for automatically restarting an inverter after power is restored from a momentary power outage, the method comprising forcibly setting the running operation to the highest operating frequency.