JPS58207897A - Drive device for ac motor - Google Patents

Abstract

PURPOSE:To prevent an inverter for an ordinary operation from stopping due to burnout trouble or the like at the motor starting time by providing an inverter exclusive for starting or stopping in addition to the inverter which performs normal operations of a plurality of motors. CONSTITUTION:A motor 1 is switched and connected to the output of an inverter 100 in the state that the rotating frequency and the voltages of the phases of the motor are coincident to those of the inverter, and only an ordinary load current is flowed to the inverter 100. When the motor 1 is ordinarily operated in this manner, an inverter 200 exclusive for starting or stopping the motors 1, 2, 3 abruptly drops its output frequency, then closes a contactor 22 and simultaneously gradually increases the output frequency, the thereby accelerating the motor 2. At this time, in case that the contactor 22 is opened when the output frequency and the phases of the inverters 100 and 200 are coincident to each other, the contactor 12 is simultaneously closed. As a result, the motor 2 is normally operated, and only the ordinary load current is flowed to the inverter 100.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an inverter device to generate multiple alternating current electricity! 1] This invention relates to a drive device for an AC motor that is capable of driving a machine and controlling the number of revolutions.

Does the inverter device (hereinafter simply referred to as inverter) that constitutes this type of drive device have a capacity commensurate with the number of AC electric motors a (hereinafter simply referred to as electric motor)? However, it is difficult to start and stop a large number of electric motors at once, and 1
A car or a small number of electric 4vIs were started and stopped sequentially. Namely.

The device shown in Figure 1 includes a frequency setter (ioi) for arbitrarily setting the output frequency;
), 2 contactors (b) each, ... + (1n)
'Electric via Jk @ (1), (2J,...5
(n) Electric motor (li, (2),...) that should be started with i connected and the output frequency of inverter 4 set in advance
・, a contact device corresponding to (n), an I hook, . . .

(1n) was started at a different timing.

In this process, with the output voltage and frequency of the inverter determined, the contactors o1), light, ..., (1nX
-The method of starting the electric motor (11* (2) t. If you want to start the engine only in this order, first turn on the contactor, then turn on the motor (1), as shown in the time chart in Figure 2.
), and after the entire starting time t6 has elapsed, the contactor (
2) and starting the electric WJ machine (2) was repeated sequentially to operate all the electric motors. This means waiting for the first motor to complete its start and for the starting current to decrease to a steady state before starting the next motor, thereby reducing the output capacity of the inverter. can be done.

On the other hand, the electric 'a' that is being driven behind the inverter 4
(lj s (2) t..., (n)'i also when stopping the contactor C11), (2),...j (in
), the output capacitance of the inverter can be reduced as well.

In such conventional drive devices, it is possible to reduce the output capacity of the inverter by delaying the operation and return timing of the contactor, but this does not mean that a large current flows during direct startup. Therefore, the output capacity of the inverter must be determined taking this large current into consideration, and furthermore, during steady operation of multiple electric motors, other electric
! There was a risk that the inverter would stop due to a burnout accident of the electric motor that is likely to occur when starting the inverter.

The present invention was made in order to eliminate the drawbacks of the conventional ones described above, and in addition to an inverter that operates a plurality of electric motors in a steady state, an inverter dedicated to starting or stopping a plurality of electric motors is used.
- The provision of an L diode can significantly reduce the output capacity of the inverter in steady operation, and 4) it can prevent the inverter from stopping in steady operation due to a burnout accident when starting the motor. The purpose is to provide drive devices.

Hereinafter, an embodiment of the present invention will be described with reference to the attached FIG. 11t.

FIG. 3 is a circuit diagram partially showing the configuration of an AC motor drive device according to the present invention in blocks, and the same reference numerals as in FIG. 1 indicate the same elements. Then, an inverter (200) dedicated to starting or stopping the electric motor (11, (2), (81), and this inverter (200) and the electric motor (ill (2), (8)
Contactor type + , (221, ■) that connects
It differs from Figure 1 in that it is newly provided.

The operation of the AC motor drive device according to the present invention constructed as described above will be explained below with reference to FIG. 4 as well.

First, the inverter (2) is operated at an arbitrary output frequency by a frequency setting device (IOI). In addition, the electric motor (1)'s (2), (s) is connected to the inverter (200).
When a starting command is given to start the motors in order k, the contactors are closed via a switching device i (not shown), and at the same time, the output frequency is gradually increased to fully accelerate the motor (1). In this case, the inverter (200) is equipped with a circuit that constantly compares and monitors the output voltage and phase of the inverter 4 and completely matches the frequency between the two and the phase of each phase of the motor (1). When these match, the contactor (6) is opened via the switching device and at the same time, the contactor (6) is closed. As a result, the motor [1] is switched and connected to the inverter (2) with the rotational frequency and the phase of each phase matching the output voltage of the inverter (2), and only the steady load current flows through the inverter (4). .

Thus, when the electric motor e (1) is in steady operation, the inverter (200) is caused to rapidly decrease the output frequency, and then, at the same time as the contactor diagram is closed, the output frequency is gradually increased, and the electric motor (2) Fully accelerate. Here, when the output frequency of the inverter (200) and the phase of each phase completely match, the contactor 1221 is opened and the contactor (121' is closed at the same time. As a result, the electric motor (2 ) is operated in a steady state, and only a steady load current flows through the inverter (100).

Thereafter, the electric motor (8) is fully driven in the same manner.

Fig. 4 shows contactor ring), (2), (to), work 121+
, 12.
1. Electric 1+1 each! (1+, (23, (81
(D start 111-A shows the acceleration time of t T in the steady operation state, and at t. the inverter (2 (10) completes starting the electric motor, and the inverter Sakaki is connected to the inverter Sakaki on the motor that has been operated steadily). , there is a preparatory time for lowering the output frequency to near zero in order to start the next motor.

4. FIG. 5 is a block diagram showing the detailed configuration of the inverter (2[30) in the AC motor drive device according to the present invention, and in the figure (2[]1) is indicated by an inno (-). (202) is the output type of the voltage transformer; (203) is a detection rectifier circuit that rectifies the voltage and generates pulses; (203) is a fl detection rectifier circuit (202).
Output signal fi □Output signal f of the ring counter (209) as a feedback signal. A phase 07 loop circuit (phase '1) that matches the phase of ut.
ocked], oop (hereinafter referred to as PLL), (20
5) A frequency-voltage converter that converts the output signal of ll:tPI,L (203) into a voltage signal, and the output signal of frequency-voltage converter r4 (205) is sent to (206) via a gate amplifier (207). Then, the rectifier circuit (208) controls the entire phase of the phase shifter, and (209) outputs a signal with a PL ratio of 06) through the gate amplifier (210).

The ring counters controlled by the inverter circuit (211)' are shown respectively. In addition, (204) has PLL (
Output f of the detection rectifier circuit (202) inputted to (203)
Output f of the in-work ring counter (209). ut
shows a relay for detecting a match.

In Fig. 5, when the electric machine (1) is fully started,
A starting command is given to inverters (2) and (200)-, and at the same time contactor @11 is closed. therefore,
jidtfI set by the frequency setting device (101) in order to operate the electric motor (1) steadily on the inverter 4.
All L number of AC voltages are generated. This inverter
The output of! voltage is applied to the detection rectifier circuit (202) via the instrument transformer (201), and the rectified voltage is applied to the PLL (
203). The PLL (203) has a built-in integration circuit, and outputs a pulse with a delayed phase with respect to the input signal fin. This PLL (203)
The pulse signal is applied to the rectifier circuit (208) via the frequency-voltage converter (205), phase shifter (206) and gate amplifier (207),
In order to obtain a voltage commensurate with the output frequency of
208) is fully controlled. Also %PLL
The pulse signal of (203) is sent to the ring counter (209)
It is also added to the inverter circuit (211) via the gate amplifier (210), and the inverter circuit (211)
The output frequency is controlled by controlling the gate phase. The output frequency of the inverter (200) is determined by the output of the ring counter (2L) 9), thereby increasing or decreasing the frequency.

Therefore, the output signal f1n of the detection rectifier circuit (202)
and the output signal f of the ring counter (209). The output frequency and phase of the inverter (200) can be made to match the output frequency and phase of the inverter 4 by causing the PLL (203) to perform the operation 6 in which U and U match. Relay (204) 1D is activated when these two match, and based on the signal of this relay (204), contactor @11 is opened via a switching device (not shown), and at the same time, contactor (2) is fully opened. If you can do it, electric @
In (1), the inverter (200) is switched and connected to the inverter (9) in a steady operating state.

Next, FIG. 6 (!L) is a time chart showing changes in the frequency of the inverter device (200) and operating states of the contactors (9) and 1211.

Here, the output frequency of the inverter (9) is constant as shown by the solid line ■, but the output frequency of the inverter (200) increases linearly at startup as shown by the dashed line @, and the output of the inverter (b) After matching the frequency, this frequency '(il-) is maintained. Also, the contactor 1?, l+ is closed for t time until the output frequency d of inverters (2) and (200) matches, and % contact is made. The contactor α1) is the contactor (2
) 11 is opened and remains in that state thereafter.

In this way, it is possible to prevent an excessive starting current from flowing into the inverter (2) when starting the electric motor (1).

In addition, in the above embodiment, the inverter for steady operation is one, and the inverter is modified to drive multiple electric motors.5For example, as shown in FIG. Ambiguous.

(200) and (300), respectively, electric motor (1)
, (2) S (6), (4) j(5) ,
(6) is connected, switches +11, m, [1ffi are sequentially operated and the inverter (400) is connected to F inverter 4l (20
0) Detecting the output frequency of l (300) and starting all the motors (1) to (6), and inverter
(200), (300) output voltage and inverter (40)
Motors (1) to (6) are synchronized with the output voltage of motors (1) to (6).
) If connected to all compatible inverters, one inverter dedicated to starting can be used to drive electric motors connected to multiple inverters in exactly the same way. .

Further, in the above embodiment, a case has been described in which the drive is started by the main drive Mt, but of course it is also possible to smoothly lower the speed of the electric motor 7″f1 by using an inverter dedicated to starting.

As is clear from the above explanation, according to the AC motor drive device of the present invention, the output capacity t of the inverter for steady operation can be significantly reduced, and at the same time, the
Can be started or stopped one by one.

Furthermore, even for special electric motors such as large-capacity permanent stone type synchronous electric motors that cannot be started directly, one inverter device for steady operation can be used with multiple C motors. JWk
cD rotation speed control becomes possible.

Further, excellent effects 7JX can be obtained, such as being able to prevent the inverter for steady operation from stopping due to a burnout accident or the like when starting the electric motor.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram partially showing the configuration of a conventional AC motor drive device, Fig. 2 is a time chart for explaining the operation of the device, and Fig. 3 is a circuit diagram of a conventional AC motor drive device according to the present invention. The configuration of an embodiment of the drive device is a circuit diagram partially shown in blocks, Figures 4 and 6 are time charts for explaining the operation of the embodiment, and Figure 5 shows the configuration of the embodiment. A block diagram showing the detailed configuration of the elements, ``7th
The figure is a block diagram partially showing the configuration of another embodiment of the AC motor drive device according to the present invention 1c. (1n~(n): AC electric '#J愼(ro)~(in), 121i~(2n): to the rock contactor)
~143): Switch rule + (200), (300), (400): Inverter device (101): Frequency setter (201): Instrument transformer (202): Detection ff rectifier circuit (203): Phase Ronta Lube Turning (204): Ri V-(205):
Frequency tfL number - voltage 16J (206/: Phase detector (2L17), (210): Gate amplifier (208)
: Rectifier circuit (209) : Ring counter (211) : Inverter circuit representative Makoto Kuzuno - Figure 1 " Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Procedural amendment (voluntary) Patent Director-General of the Agency 2. Title of the invention: AC motor drive vch. 3. To the representative of the person making the amendment: Hitoshi Katayama. 6. Contents of amendment (1) The claims of the specification are amended as shown in the attached sheet. (2) "It is difficult to start or stop all at once" in lines 7 and 8 of page 2 of the specification. This statement has been corrected to ``Starting all at once requires a large output capacity of the inverter, and stopping all at once is often difficult due to production considerations as a drive device.'' 7. Supply an AC voltage to a plurality of AC motors, and calculate the Shin mantissa of this alternating voltage. The alternating current motor can be started by installing an inverter that can brake the rotational speed of the alternating current motor by changing the rotational speed of the alternating current motor, and by supplying alternating voltage to at least one of the alternating current motors, and by changing the phase of the alternating current voltage. A second inverter device capable of matching the alternating current voltage phase of the first/inverter device and the alternator to be started are connected to the second inverter device; It is characterized by comprising a switching device that connects the first inverter device to the first inverter device of the first inverter device when the start-up is completed on the condition that the alternating current voltage phases of the inverter devices match. AC electric drive device.

Claims (1)

[Claims] a first inverter device capable of supplying alternating current voltage to a plurality of alternating current motors and controlling the rotational speed of the alternating current motors by changing the frequency of the alternating current voltage; and supplying alternating current voltage to at least one of the alternating current motors. a second inverter device that can operate the AC electric Mi mirror by changing the frequency of the AC voltage and can match the AC voltage phase with the AC voltage phase of the first inverter device; The AC motor that is to be started is connected to the second inverter device, and on condition that the AC voltage phases of the first and second inverter devices match, the motor that has been started is connected from the second inverter device to the second inverter device. 1. An AC voltage phase drive device comprising: a switching device for switching connection to a first inverter device.