JPS61170287A - Controller of ac elevator - Google Patents

Abstract

PURPOSE:To reduce the size and the weight of a controller by charging a smoothing capacitor by a double voltage rectifier, thereby eliminating a transformer. CONSTITUTION:When a breaker 1 is closed, if the potential of a smoothing capacitor 4 is the prescribed value of lower, a voltage detector 20 is inoperative. Accordingly, its contact is closed. Thus, a charge command relay 36 is energized to close contacts 36a, 36b. Thus, the capacitor 4 is charged by a double voltage rectifier by diodes 31, 32, resistors 33, 34, and a capacitor 35. If the voltage of the capacitor 4 becomes the prescribed value or higher by charging, the detector 20 is operated to close contacts 36a, 36b, and the charging of the capacitor 4 is stopped. Thus, since the capacitor 4 is charged by a double voltage rectifier, a transformer is eliminated to reduce the size and the weight of the controller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an elevator driven by an AC motor.

[Conventional technology]

In recent years, with the development of inverters, elevators that control the induction motor for car hoisting with variable voltage and variable frequency alternating current are becoming mainstream. 3 and 4 are diagrams showing a conventional control device disclosed in Japanese Unexamined Patent Publication No. 5≦+-101,70. In the figure, R, S, and T are three-phase AC power supplies, 1
2 is a circuit breaker connected to electric currents mR, s, and T; 2 is an electromagnetic contactor that is energized when the car starts and deenergized when it stops;
3 is a converter connected to contacts 2a to 2c, 4 is a smoothing capacitor connected to the DC side of converter 3 to smooth the DC output, and 5 is connected to both ends of smoothing capacitor 4. A well-known inverter that converts direct current into alternating current using transistors and diodes and makes the voltage and frequency variable; 6 is a three-phase induction motor connected to the alternating current side of inverter 5; 7 is three-phase induction motor 6 8 is the brake car coupled to the brake car 7.
A brake shoe 9 is provided facing the outer periphery of the brake wheel 7 and applies braking force to the brake wheel 7 by the force of a spring (not shown). 10 is a drive 1IIi wheel of a hoist driven by a three-phase induction motor 6;
Reference numeral 11 indicates a main cable which is wound around a rope $10 and has a car 12 and a counterweight 13 connected to both ends thereof, 14 is a speedometer generator which is directly connected to the three-phase induction motor 6 and issues a speed signal, and 15 is a speed command signal. A speed command generator that emits a speed command, 1
6 is an inverter control device that gives a firing command to control the voltage and frequency to the inverter 5 from the speed command signal and the speed signal; 17 is a device whose primary winding is connected to the circuit breaker 1 and whose secondary winding is higher than the primary winding; A three-phase transformer 18 for external pressure that induces voltage has its AC side connected to the secondary winding of the transformer 17, its DC negative side connected to one end of the smoothing capacitor 4, and its DC positive side connected to the smoothing capacitor 4 via an impedance 19. A rectifier connected to the other end, 20 a voltage detector that operates to close a contact 208 when the voltage of the smoothing capacitor 4 is higher than a predetermined value, and 21 a start command relay that closes when a car start command is issued. The contacts (+) and (-) are DC power supplies.

Next, the operation will be explained. When the circuit breaker 1 is turned on, the transformer 17 is excited, and an alternating current voltage is induced in the secondary winding of the transformer. This voltage is converted into a DC voltage by a rectifier 18, and the smoothing capacitor 4 is charged via an impedance 19. When the smoothing capacitor 4 is charged and its voltage exceeds a predetermined value, the voltage detector 2o is activated and the contact 20a is closed.

Further, while the car 12 is stopped, the brake shoe 8 is pressed against the brake pad 7 by the force of the spring.

When a starting command is issued to the car 12, the brake coil 9 is energized and the brake shoe 8 is separated from the brake JF7.

At the same time, the start command relay contact 21 closes and (+)→
Start command relay contact 21 → contact 20a → electromagnetic contactor 2 →
The electromagnetic contactor 2 is energized by the (-) circuit, and the contacts 2a to 2c
is closed, the variable voltage/variable frequency AC power converted via the converter 3, smoothing capacitor 4, and inverter 5 is supplied to the three-phase induction motor 6. Now, three-phase induction electric + fl! 6 starts up, and the cage 12 runs.

The inverter control device 16 controls the inverter 5 and adjusts its output voltage and frequency, thereby increasing the speed of the three-phase induction motor 6, i.e., the car 12.
The traveling speed of the vehicle is automatically controlled at all times. When the car 12 approaches the scheduled stop floor, the start command relay contact 21 opens and the electromagnetic contactor 2 is deenergized. As a result, the contacts 2a to 2c are opened, and the converter 3 is disconnected from the power source Rt'S, T. At the same time, the brake coil 9 is deenergized, so a braking force is applied to the brake turret 7, and the car 12 stops at the floor where it is scheduled to stop.

[Problem that the invention seeks to solve]

When the starting command for the car 12 is issued and the electromagnetic contactor 2 is energized, if the voltage of the smoothing capacitor 4 is low, a large charging current will flow, resulting in welding of the contacts 2a to 2c, shortening of the life of the smoothing capacitor 4, and damage to the converter 3. , an undesirable event such as a malfunction of the circuit breaker 1 occurs.

The transformer 17 is designed to prevent such a phenomenon, that is,
Although it is provided to boost the power supplies R, S, and T to charge the smoothing capacitor 4 to a sufficiently high voltage, it is completely unnecessary for the operation function of the car 12.

It is uneconomical to use a transformer only for charging the smoothing capacitor 4, and it is also against the need to make the control device smaller and lighter.

Furthermore, in the configuration shown in FIG. 3, if the smoothing capacitor 4 deteriorates, the input/output 5 or the converter 3 suffers a short-circuit failure, there is no means to protect the transformer 17, rectifier 18, and impedance 19, which may cause them to burn out. There was fear.

The present invention solves the above-mentioned problems and provides an AC elevator control device that can charge a smoothing capacitor to a high voltage without using a transformer and protect the charging circuit.

[Means for solving problems]

The AC elevator control device according to the present invention charges a smoothing capacitor with a voltage doubler rectifier circuit, and is provided with a circuit for detecting an abnormality during charging, and stops charging when an abnormality is detected.

[Effect]

The smoothing capacitor in this invention is charged to a sufficiently high potential by a voltage doubler rectifier circuit. In addition, in the event of an abnormality,
Charging is stopped and burnout of the charging circuit is prevented.

〔Example〕

An embodiment of the present invention will be described below.

In Figures 1 and 2, the same symbols as in Figures 3 and 4 indicate the same or equivalent parts, 2d is the normally open contact of the electromagnetic contactor 2, 2e is also the normally closed contact, 201) is the voltage detection 31 and 32 are diodes, 33 and 34 are resistors, 35 is a capacitor, 3
6 is a charging command relay for closing the charging circuit of the smoothing capacitor 4, 36a to 36c are its normally open contacts, and 36d
37 is its normally closed contact, and 37 is an abnormality detection relay that operates when the charging command relay 36 continues to be energized for a predetermined period of time.
is its normally open contact, and 371) is its normally closed contact.

Note that the diodes 31 and 32, the resistors 33 and 34, and the capacitor 35 constitute a voltage doubler rectifier circuit.

According to the embodiment of the control device for an AC elevator of the present invention configured as described above, when the circuit breaker 1 is closed, if the potential of the smoothing capacitor 4 is below a predetermined value, the voltage detector 2o is activated. Since it is in the operating state, its contact 201) is closed. Therefore, charging command relay 36 is energized and contacts 36a to 36c are closed.

Now, considering a half cycle in which the S phase of the power supply is positive and the R phase is negative,
A current flows through the circuit of diode 31 → resistor 33 → capacitor 35 and charges capacitor 35. Next, in the half cycle when the R phase is positive and the S phase is negative, current flows through the circuit of capacitor 35 → resistor 34 → diode 32 → normally open contact 36a → smoothing capacitor 4 → normally open contact 36b, so the AC voltage of R8 phase The smoothing capacitor 4 is charged with the sum of the charging voltage of the capacitor 35 and the charging voltage of the capacitor 35.

When the voltage of the smoothing capacitor 4 becomes equal to or higher than a predetermined value due to charging, the voltage detector 20 is activated, the contact 20b is opened, and the charging command relay 36 is deenergized. As a result, contact 36a+3
6b is opened and charging of the smooth capacitor 4 is stopped. Since the contact 20a is closed at the same time, when a car starting command is issued and the contact 21 is closed, the electromagnetic contactor 2 is turned on and the car is enabled to run. The subsequent operations are the same as in the conventional example.

Next, the operation in the event of an abnormality will be explained. Generally, an electrolytic capacitor is used as the smoothing capacitor 4, but when the smoothing capacitor 4 reaches the final stage of life, the dielectric loss tangent increases and the leakage current increases, resulting in a longer charging time.

Further, if the inverter 5 or converter 3 has a short circuit failure, charging of the smoothing capacitor 4 becomes impossible. If the charge command relay 36 continues to be energized for a predetermined period of time or more for the reason described above, the abnormality detection relay 37 will be energized in the circuit from (+) → contact 36c → abnormality detection relay 37 → (-), and the contact will be activated. It is self-retained by closing 37a. At the same time, the charging command relay 36 is deenergized by opening the contact 37b, and charging is stopped. If smoothing capacitor 4 is insufficiently charged,
Voltage detector 20 is inoperative, therefore its contacts 20a
Since it is open, the electromagnetic contactor 2 cannot be turned on, and the starting of the car can be prevented.

Further, in the above embodiment, the charge command relay 36 does not have a time limit, but it may be provided with a slight time limit to serve as a time limit return relay. In this case, the number of times the charging command relay 36 repeats energization and deenergization while the car is stopped can be reduced.

〔Effect of the invention〕

As described above, according to the present invention, since the smoothing capacitor is charged by the voltage doubler rectifier circuit, a transformer is not required, and the control device can be made smaller and lighter.

Furthermore, in the event of an abnormality, charging is stopped and the car is prevented from starting, thereby preventing secondary disasters and improving safety.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the AC elevator control device of the present invention, Fig. 2 is the same circuit diagram, Fig. 3 is a configuration diagram showing a conventional AC elevator control device, and Fig. 4 is the same. It is a conventional circuit diagram. 1... Breaker, 2... Magnetic contactor, 3... Converter, 4... Smoothing capacitor, 5... Inverter,
6...Three-phase induction motor, 12...Cage, 20...
Voltage detector, 21...Start command relay contact, 31.3
2...Diode, 33.34...Resistor, 35...
・Capacitor, 36... Charging command relay, 37...
Abnormality detection relay. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A converter converts commercial AC power to DC, this DC is smoothed by a smoothing capacitor, this is converted to variable frequency AC by an inverter, and this converted power is supplied to the AC motor for car hoisting. A magnetic contactor connected between the commercial AC power source and the converter, a voltage doubler rectifier circuit connected to the commercial AC power source, and a switching means connected between the voltage doubler rectifier circuit and the smoothing capacitor. An AC elevator control device consisting of: