JP4378935B2 - Electric motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an electric motor control device using an inverter, particularly an elevator control device.
[0002]
[Prior art]
In recent elevators, a hoisting machine having a permanent magnet type synchronous motor is provided in a hoistway to constitute a control device as shown in FIG. 3 (see, for example, Patent Document 1). ).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-309475
That is, a three-phase AC power source 1, a converter 2 that converts AC voltage into DC voltage, a capacitor 3 for smoothing the converter voltage, an inverter 4 that converts DC voltage into AC voltage, and a hoisting machine driven by the inverter output voltage The inverter output voltage is applied to the hoisting machine 5 by the contact 10a of the magnetic contactor, and the armature winding (input terminal side) of the hoisting machine 5 is resistance by the contact 10b of the electromagnetic contactor during emergency braking. 6 is short-circuited.
[0005]
Here, the reason why the resistor 6 is inserted is to generate a power generation braking torque corresponding to the elevator car speed during the rescue operation after an abnormal stop. However, the contacts 10a and 10b of the electromagnetic contactor This is also to prevent an output short circuit accident of the inverter 4 even if the operation timing is slightly shifted. In addition, if a direct-current operated DC electromagnetic contactor is used, the contact can be easily delayed (by parallel connection of a resistor and a capacitor), but in general, a DC electromagnetic contactor is large and very expensive. is there.
[0006]
[Problems to be solved by the invention]
By the way, the presence of this large-capacity resistor 6 is the main cause of the bulk of the device itself, and it is best if it can be eliminated, but if this resistor 6 does not exist, before the contact 10a of the electromagnetic contactor opens. If the contact 10b is closed, the output of the inverter 4 is short-circuited, so that the inverter 4 is damaged.
[0007]
The present invention has been made in view of the above points, and even if an inexpensive AC electromagnetic contactor is used, the operation order of the contacts always operates in the correct order, and a protective resistor can be dispensed with. An object is to provide a control device.
[0008]
[Means for Solving the Problems]
In the present invention, the output voltage of the inverter is applied to the electric motor via the contact of the first electromagnetic contactor, the rotational speed of the electric motor is controlled, and the input terminal of the electric motor is connected to the second electromagnetic contactor during emergency braking. The second electromagnetic contactor is energized through a diode bridge via the normally closed contact of the first electromagnetic contactor, and the first electromagnetic contactor is The second electromagnetic contactor is energized after the normally open contact of the second electromagnetic contactor is closed after the second electromagnetic contactor is energized. When an abnormality occurs, the second electromagnetic contactor is excited for a predetermined time even when the energization is stopped. An electric motor control device characterized in that the configuration is maintained .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention can realize the delay operation of the second magnetic contactor at low cost.
[0010]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing a main circuit of a control device according to the present invention, and FIG. 2 is a control circuit diagram of an electromagnetic contactor according to the present invention. In the figure, the same reference numerals as those in FIG. 3 denote the same components, but 20 and 30 are electromagnetic contactors according to the present invention, 20a is a normally open contact of the electromagnetic contactor 20, and 20b is a normal contact of the electromagnetic contactor 20. A closed contact, 30 a is a normally open contact of the electromagnetic contactor 30, and 30 b is a normally closed contact of the electromagnetic contactor 30.
[0011]
Next, for example, 11 is a 100V AC power source, R1 and R2 are resistors, C is a capacitor, D1 to D4 are diodes, and a known bridge is configured to convert an AC voltage into a DC voltage. For example, a very inexpensive AC electromagnetic contactor 30 is connected to this DC voltage circuit system, and the other AC electromagnetic contactor 20 is connected to the AC power supply 11 via a normally open contact 30a of the AC electromagnetic contactor 30. ing.
[0012]
First, in FIG. 2, when the switch SW is turned on at the time of starting the elevator, an AC voltage is supplied to the coil of the AC electromagnetic contactor 30 through the switch SW, the contact 20b, and the diode bridge (D1 to D4). 30 is excited, and the AC electromagnetic contactor 20 is also excited by closing the contact 30a. Therefore, in the main circuit of FIG. 1, after the contact 30b is opened, the contact 20a is closed, and the output voltage of the inverter 4 is applied to the hoisting machine 5, so that known elevator speed control is performed. In addition, after the contact 20b is opened, the excitation of the electromagnetic contactor 30 is held by the reduced voltage by the resistors R1, R2, and the capacitor C. Normally, an AC electromagnetic contactor cannot be used in a DC circuit, but it can be used by performing this decompression operation.
[0013]
On the other hand, when an abnormality occurs and the switch SW is opened, the magnetic contactor 20 is immediately demagnetized, and the voltage to the hoisting machine 5 is cut by opening the contact 20a. In this case, the flywheel effect by the diodes D1 to D4 maintains the excitation for a predetermined time, so that the closing of the contact 30b always operates after the opening of the contact 20a. For this reason, since the contacts of the electromagnetic contactors 20 and 30 are always opened and closed in the correct order of (opening of the contact 20a) → (closing of the contact 30b), it is extremely safe.
[0014]
Here, the hoisting machine 5 is not particularly limited, and any hoisting machine may be used. However, for example, an apparatus having a configuration as shown in FIG. 4 may be used. That is, in the apparatus described in International Application No. PCT / JP02 / 01220, three places above and on both sides of the sheave 42 around which the rope 40 with the elevator weight suspended on one side and the counterweight suspended on the other is wound. Rollers 161, 162, 163 are arranged on the belts, belts 164 are stretched around these rollers 161, 162, 163, and the rope 40 wound around the sheave 42 by the belt 164 is pressed toward the sheave 42. The roller 161 is driven by an electric motor.
[0015]
【The invention's effect】
As described above, according to the present invention, it is possible to easily perform a delay operation using an extremely inexpensive AC electromagnetic contactor, so that an inverter short circuit accident can be prevented without using a protective resistor. It can be prevented in advance. Also, a control device with a low cost can be obtained.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a main circuit of a control device according to the present invention.
FIG. 2 is a circuit diagram showing a control circuit of an electromagnetic contactor according to the present invention.
FIG. 3 is an overall view showing an example of an elevator hoisting machine.
FIG. 4 is a circuit diagram showing a main circuit of a conventional control device.
[Explanation of symbols]
4 Inverter 5 Hoisting Machine 10, 20, 30 Magnetic Contactor 10a Normally Opened Contact 10b of Magnetic Contactor 10 Normally Closed Contact 20a of Magnetic Contactor 10 Normally Opened Contact 20b of Magnetic Contactor 20 Normally Closed Contact of Magnetic Contactor 20 30a Normally open contact 30b of the magnetic contactor 30 Normally closed contact D1, D2, D3, D4 of the magnetic contactor 30 Diode R1, R2 Resistor C Capacitor

Claims (3)

The output voltage of the inverter is applied to the electric motor through the contact of the first electromagnetic contactor to control the rotation speed of the electric motor. During emergency braking, the input terminal of the electric motor is connected to the contact of the second electromagnetic contactor. The second electromagnetic contactor is energized through a diode bridge via the normally closed contact of the first electromagnetic contactor, and the first electromagnetic contactor is connected to the second electromagnetic contactor. The contactor is energized and energized after the normally open contact of the second electromagnetic contactor is closed, and when an abnormality occurs, the second electromagnetic contactor is kept excited for a predetermined time even when the energization is stopped. An electric motor control device. It said second electromagnetic contactor, a configuration that is energized through the first electromagnetic contactor normally closed normally closed contact in parallel to the resistor and the capacitor is provided in the contact opening the first electromagnetic contactor after the The motor control device according to claim 1, wherein the motor control device is provided. The motor control device according to claim 1, wherein each of the first and second electromagnetic contactors is an AC contactor.

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