JPH0746071Y2 - Inverter automatic switching circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an automatic switching circuit of an inverter when a motor used in a fiber configuration is controlled by a spare inverter and a regular inverter.

[Conventional technology]

Textile machinery is basically a continuous operation, and stopping the inverter leads to a stop of the entire equipment, and it takes a lot of time to restart the equipment, which greatly affects it. Therefore, a spare inverter may be provided to minimize equipment downtime.

This spare inverter is operated at the time of maintenance / inspection of the regular inverter or at the time of trouble. When the maintenance / inspection of the regular inverter and the trouble are recovered, the standby inverter is synchronously controlled (phase control) with the regular inverter and then switched to the regular inverter. The spare inverter is also used in the traverse of textile machines. The traverse is intended to wind the yarn evenly by winding the yarn left and right, but it is usually operated by slightly changing the traverse speed periodically.

An example of the operation pattern will be described with reference to FIG.

In FIG. 4, since the operating frequency of the inverter constantly changes with time, it was extremely difficult to perform phase matching when switching the electric motor from the spare inverter to the regular inverter. In particular, control is impossible during the period of sharp fall b and rise b.

Therefore, conventionally, the inverters have been switched when the frequencies of the standby inverter and the regular inverter match.

[Problems to be solved by the device]

However, although the frequencies of the spare inverter and the common inverter match, the voltage phase may differ,
If an excessive current flows to the inverter and the capacity of the inverter is small, the protection circuit of the inverter may operate and stop.

The present invention has been made in view of the above-mentioned points, and its purpose is to perform stable phase automatic inverter switching circuit by performing phase matching of both inverters after the frequencies of the spare inverter and the common inverter match. To provide.

[Means for Solving the Problems]

In other words, the means for achieving the purpose is to use a traverse inverter equipped with a spare inverter in the common inverter, and input the signal from the reference phase generator and the signal of the PWM control signal generation circuit in the spare inverter to the common inverter. It consists of a phase difference detector, a limiter circuit that inputs this output signal, and a comparator that operates according to the set value of this limiter circuit.When switching between the standby inverter and the common inverter, the frequencies of both inverters match. After that, we performed phase matching with a certain prohibited section,
It is configured so that switching is performed in a designated section after phase matching.

[Action]

The operation will be described together with the embodiment described below.

〔Example〕

FIG. 1 is an overall configuration diagram showing an embodiment of an inverter switching circuit of the present invention, FIG. 2 is a detailed view of the regular inverter of FIG. 1, 1 is a regular inverter, 2 is a spare inverter,
3 is a switch, and 4 is an electric motor. Each of the regular inverter 1 and the spare inverter 2 includes a converter section 1A, 2A, a filter section 1B, 2B, a main circuit section of the inverter section 1C, 2C, a frequency pattern generation circuit 1D, 2D, a PWM control signal generation circuit 1E, 2
E, formed by the control circuit of the drive circuit 1F, 2F, the switching device 3A or
One of the inverters is connected to the electric motor 4 via 3B.

As shown in FIG. 2, a phase difference detector for inputting the signal θ ₁ from the reference phase generator 11E of the present invention and the signal of the PWM control signal generating circuit 2E included in the spare inverter 2 to the common inverter 1 as shown in FIG. 12E, a limiter circuit 13E that inputs this output signal, and a comparator 14E that operates according to the set value of this limiter circuit 13E. When switching between the spare inverter 2 and the common inverter 1, the frequencies of both inverters match. After that, the phase matching is performed with a certain prohibited section provided, and after the phase matching, switching is performed in the designated section. 10E is a PWM control signal generator, WL is a synchronous ramp, a is a frequency setting signal from the frequency pattern generation circuit 1D, and b is a drive circuit signal from the PWM control signal generator 10E.

Next, the operation will be described with reference to the time chart of FIG.

In describing the operation of the present embodiment, it is assumed that the regular inverter 1 is stopped due to maintenance or trouble or the like, and the electric motor 4 is operated by the spare inverter 2 via the switch 3B side.

Here, when the service inverter 1 is restored and a sequence command is given to switch the electric motor 4 from the spare inverter 2 to the service inverter 1, the service inverter 1 switches the switch 3A.
Is started in the open state, and at the same time, the spare inverter 2
Frequency pattern signal c from the frequency pattern generation circuit 2D of
In response to this, operation is performed in the same pattern (same frequency ... However, there is a transmission delay).

Then, when a sequence command for starting the phase control is given, the regular inverter 1 detects the phase difference from the spare inverter 2 by the phase difference detector 12E and starts the phase control. Then, the phase difference detector 12E, and detects the phase difference delta ^theta of the preliminary inverter 2 and conventional inverter 1, a so-called PLL circuit for controlling, in addition to their frequency set the (F = F ± Δ ^θ) phase formation is doing.

Phase difference delta ^theta decreases, operates the comparator 14E is where it becomes less than a predetermined value, and outputs a sequence signal of "phase matching" = "synchronization completion" to the sequence circuit. Sequentially, after the phase matching confirmation processing time, "synchronization is completed" with a time delay, the switch 3 is switched from the spare inverter 2 side to the common inverter 1 side, and the electric motor 4 is controlled by the output of the common inverter 1 thereafter.

It should be noted that the common inverter 1 has restrictions on the phase control and switching operation.

From FIG. 3, the phase control prohibition section C is provided just before and immediately after the steep rise and fall of the disturb waveform A, and the disturb waveform A is also disturbed when the switch 3 can be switched after "phase matching". A switching section E is provided so that it is possible after passing the center frequency. After the switching from the spare inverter 2 to the regular inverter 1 is completed, the phase control and the like from the spare inverter 2 are all stopped.

[Effect of device]

As described above, according to the present invention, after the frequencies of the spare inverter 2 during the traverse operation and the frequency of the regular inverter 1 match, both inverters are phase-matched and switched to the regular inverter 1 after the synchronization is completed. This enabled stable automatic switching of the inverter.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a detailed diagram of a main part of FIG. 1, FIG. 3 is a time chart diagram, and FIG. 4 is an operation for explaining a conventional one. It is a pattern characteristic diagram. 1 ... Regular inverter, 2 ... Spare inverter, 3 ...
Switching device, 4 ... Electric motor, 11E ... Reference phase generator, 1E, 2E
...... PWM control signal generation circuit, 12E ...... Phase difference detector, 13E
...... Limiter circuit, 14E …… Comparator.

Claims (1)

[Scope of utility model registration request] 1. A traverse inverter having a spare inverter as a common inverter, wherein a phase difference detector for inputting a signal from a reference phase generator and a signal of a PWM control signal generating circuit included in the spare inverter to the common inverter. And a limiter circuit that inputs this output signal and a comparator that operates according to the set value of this limiter circuit.When switching between the standby inverter and the common inverter, after the frequencies of both inverters match, a certain An automatic switching circuit for an inverter, which is configured to perform phase matching with a prohibited section, and to switch at a designated section after phase matching.