JPH02193892A - Variable speed hoist and control method thereof - Google Patents

Abstract

PURPOSE:To enhance safety by controlling a brake for an electric motor in such a condition that both an output signal generated at the time of start of an inverter and an output signal generated at the time of start of a hoist are turned ON, so that the brake can be prevented from being always opened when the output signal of the inverter fails. CONSTITUTION:Even if an AR terminal fails to output an ON-signal before a low-speed relay 5 is electrified, only the electrification of both a control relay 10 and a brake relay 9 is quickened at the time of start of an inverter 2, and the frequency of the inverter 2 is immediately raised up to the low-speed frequency. As a result, the occurrence of the falling accident of a hoisted cargo can be prevented. Further, even if both a RUN terminal and an AR terminal have failed before the low-speed relay 5 is electrified, only the electrification of both the control relay 10 and the brake relay 9 is quickened at the time of start of the inverter 2, and in the same manner the falling accident of the hoisted cargo is not caused.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a variable speed hoist and a control method thereof.

[Conventional technology]

As a conventional variable speed hoisting machine, one has been devised in which a hoisting electric motor is connected to an AC power source via an inverter, and a brake for the electric motor is controlled by one output signal of the inverter. As related to such a hoisting machine, Japanese Patent Application Laid-Open No. 5
Publication No. 9-48390 is published.

[Problem to be solved by the invention]

In such conventional variable speed hoisting machines, when the output signal of the inverter fails, the ON signal continues to be output, and the brake is constantly released, which may cause the suspended load to fall.

SUMMARY OF THE INVENTION An object of the present invention is to provide a variable speed hoist and a control method thereof, in which the brake does not always open even if the output signal of an inverter fails.

[Means to solve the problem]

The present invention relates to a variable speed hoisting machine in which a first hoisting motor is connected to an AC power source via an inverter, and a brake for the motor is controlled by an output signal of the inverter. The variable speed hoist is characterized in that the electric motor brake is controlled in a state where both the output signal and the output signal generated when starting the upper machine are turned on.

The present invention provides a variable speed hoist in which a one-roll soil motor is connected to an AC power source via an inverter, and a brake for the motor is controlled by an output signal of the inverter, in which two outputs are generated when the inverter starts operating. The variable speed hoist is characterized in that the electric motor brake is controlled in a state where a signal is turned on.

The present invention provides a variable speed hoisting machine in which a hoisting motor is connected to an AC power source via an inverter, and a brake for the motor is controlled by an output signal of the inverter. The variable speed hoist is characterized in that the electric motor brake is controlled in a state in which both the output signal and the output signal generated when the operating frequency is reached are turned on.

The present invention provides a variable speed hoisting machine in which a hoisting motor is connected to an AC power supply via an inverter, and a brake for the motor is controlled by an output signal of the inverter. A terminal is provided on the inverter, an AR terminal is provided on the inverter that generates an ON signal when a low speed frequency is reached after starting the inverter, and a light emitting element of the first solid state relay is provided between the RUN terminal and the DC power supply terminal. and connect the above A
A light emitting element of a second solid state relay is connected between the R terminal and the DC power supply terminal, the light receiving elements of both the light emitting elements are connected in series to a control relay, and the control relay controls the brake. The variable speed hoist is characterized by:

The present invention provides a control method for a variable speed hoisting machine in which a first hoisting motor is connected to an AC power supply via an inverter, and a brake for the motor is controlled when an ON signal is generated in the output signal of the inverter. 6. A method for controlling a variable speed hoist, characterized in that the brake for the electric motor is released when two output signals generated when starting operation of the motor are turned on. In the hoisting machine, if the output signal of the inverter fails, even if the ON signal continues to be output, the electric motor brake will not be released unless the other signal is ON, so the suspended load will not fall. In addition, since the output signal generated when the inverter starts up and the output signal generated when the low speed frequency is reached, the brake can be controlled with a highly versatile inverter, and the rated torque is output to the motor. The electric motor can be started in this condition.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

The electric motor 1 for hoisting and lowering the suspended load has a second
As shown in the figure, it is connected to an AC power source 3 via an inverter 2. AC power supply 3 is R phase.

It is a three-phase power supply consisting of S phase and T phase, and R of inverter 2
Connected to terminal, S terminal, and T terminal.

The electric motor 1 is three-phase, and the U terminal of the inverter 2.

■Connected to the terminal and W terminal. S phase of AC power supply 3,
A low speed relay 5 and a high speed relay 6 are connected in parallel between the T phases via a push button switch 4. push button switch 4
has a built-in low-speed contact 4a that closes when the negative stage is pressed, and a high-speed contact 4b that closes when the second stage is pressed. The low speed contact 4a is connected in series with the low speed relay 5, and the high speed contact 4b is connected in series with the high speed relay 6.

The inverter 2 is provided with an H terminal, an L terminal, and a 00M terminal. A relay contact 6a that is opened and closed by a high-speed relay 6 is connected between the H terminal and the 00M terminal, and a relay contact 6a that is opened and closed by a high-speed relay 6 is connected between the H terminal and the 00M terminal. A relay contact 5a that is opened and closed by a low-speed relay 5 is connected between the two. Inverter 2 is another 0
A 0M terminal is provided and connected to the DC power supply connection terminal GD.

Furthermore, the inverter 2 is provided with a RUN terminal and an AR terminal. The RUN terminal is connected to the DC power supply connection terminal VDD via the light emitting element 7a of the first solid state relay 7, and the AR terminal is connected to the DC power supply connecting terminal VDD via the light emitting element 8a of the second solid state relay 8. RUN terminal is inverter 2
An on signal is output when the machine is running, and an off signal is output when it is stopped. An ON signal is output from the AR terminal when the inverter 2 is at a predetermined frequency, and an OFF signal is output at other times. This predetermined frequency means a low-speed frequency that can ensure the rated torque of the electric motor 1 and an arbitrarily set high-speed frequency. Relay 10 for controlling brake relay 9
is connected between the S phase and T phase of the AC power source 3 via the light receiving element 7b of the first solid state relay 7 and the light receiving element 8b of the second solid state relay 8 in series. In parallel with the light receiving element 8b of the second solid state relay 8,
A series circuit of the second contact 10b of the control relay 10 and the second contact 5b of the low-speed relay 5 is connected. The brake relay 9 is connected to the AC power source 3 through the first contact 10a of the control relay 10 and the third contact 5c of the low-speed relay 5 in series.
It is connected between the S phase and T phase of. The brake 11 is connected between the R phase and the S phase of the AC power source 3 via a first contact 9a and a second contact 9b of the brake relay 9. The brake 11 is configured to open the electric motor 1 when energized and brake the electric motor 1 when the energization is stopped.

Next, the operation of such a variable speed hoist will be explained.

First, by pressing the first stage of the pushbutton switch 4, the low speed contact 4a is closed, the low speed relay 5 is energized, the first contact 5a is closed, and the L terminal of the inverter 2 is turned on. As a result, an on signal is output to the RUN terminal and the inverter 2 is activated at 5 Hz. The light emitting element 7 of the first solid state relay 7 is activated by the ON signal of the RUN terminal.
a emits light, and its light receiving element 7b turns on. Further, when the inverter 2 is started, the output frequency of the inverter 2 gradually increases, and when it reaches the low speed frequency (10 Hz), it outputs at that constant frequency. The reason why the starting frequency of the inverter 2 is set as low as 5 Hz is to reduce the inrush current at the time of starting. An on signal is output to the AR terminal at this low speed frequency.

The light emitting element 8a of the second solid state relay 8 emits light in response to the ON signal of the AR terminal, and the light receiving element 8b thereof is turned on. The control relay 10 is energized by turning on the two light receiving elements 7b and 8b, and closes the first contact 10a and the second contact 10b. Since the low-speed relay 5, which is already energized, closes its second contact 5b and third contact 5C, the control relay 10 closes the light receiving element 7b and the contact 10b.
.

5b, and the brake relay 9
energize. When the brake 9 is energized, its contacts 9a, 9
b is closed, the brake 11 is energized, and the electric motor 1 is released. At low speed frequencies, the electric motor 1 is set to output a rated torque.

After operating the electric motor 1 at low speed at the low speed frequency, pressing the second stage of the pushbutton switch 4 closes the high speed contact 4b, energizes the high speed relay 6, closes the contact 6a, and turns the inverter 2 to H. Turn on the terminal. As a result, the output frequency of the inverter 2 gradually increases, and when it reaches a predetermined high-speed frequency, it is output at that constant frequency. Inverter 2
While the output frequency is increasing, an off signal is output to the AR terminal, but the control relay 10 is connected to the light receiving element 7b of the first solid state relay 7, the second contact 5b of the low speed relay 5, and the control relay 10. Since the brake relay 9 is self-held via the second contact 10b of the control relay 10 and the third contact 10a of the control relay 10,
Electricity continues through the contact 5c, and the brake 11 maintains the state in which the motor 1 remains open. When the predetermined high-speed frequency is reached, an on signal is output to the AR terminal, the second solid state relay 8 is activated, and its light receiving element 8b is turned on, but there is no change in the energization of the control relay 10 and the brake relay 9. .

After the motor 1 is operated at high speed at the high speed frequency, the second stage of the pushbutton switch 4 is pulled back to open the high speed contact 4b to stop energizing the high speed relay 6, and to open the contact 6a. Turn off the H terminal of inverter 2. As a result, the output frequency of the inverter 2 gradually decreases, and when it reaches the low speed frequency, it is output at that constant frequency. While the output frequency is decreasing, an off signal is output to the AR terminal, but since the control relay 10 is self-maintained, the brake relay 9 continues to be energized.

After operating the electric motor 1 at low speed at this low speed frequency, the first stage of the pushbutton switch 4 is pulled back to open the low speed contact 4a and stop energizing the low speed relay 5.
A is opened to turn off the L terminal of inverter 2. When the low-speed relay 5 is de-energized, its second contact 5b and third contact 5c are opened and an off signal is output to the AR terminal, so the control relay 1o and the brake relay 9 are de-energized. Contacts 9a and 9b close and brake 11
is activated. This brakes the electric motor 1 to stop it. When the L terminal of inverter 2 is turned off, inverter 2
The output frequency gradually decreases until the output frequency at startup (5
Hz), the inverter 2 stops and an off signal is output to the RUN terminal.

In such a variable speed hoist, even if the RUN terminal fails and an on signal is output before the low speed relay 5 is energized as shown in FIG. Low speed relay 5, high speed relay 6, control relay 10
and the brake relay 9 can be operated. Furthermore, as shown in FIG. 4, even if the AR terminal fails and an ON signal is output before the low-speed relay 5 is energized, the control relay 10 and brake relay 9 are energized when the inverter 2 is started. Since the frequency of the inverter 2 immediately increases to the low speed frequency, there is no possibility of the suspended load falling.Furthermore, as shown in FIG.
Even if both the RUN terminal and the AR terminal fail before the inverter is energized, the control relay 10 and the brake relay 9 will only be energized earlier when the inverter 2 is started, and the suspended load will not fall. .

This is because the output signal generated when the inverter 2 is started and the output signal generated when the low speed frequency is reached are used as signals for controlling the brake.

The brake 11 can be controlled by the highly versatile inverter 2, and the electric motor 1 can be started in a state where the rated torque is output to the electric motor 1.

Since the first contact 10a of the control relay 10 and the third contact 5c of the low-speed relay 5 are connected in series with the brake relay 9, it is possible that either the first contact 10a or the third contact 5c has a melt layer failure. On the other hand, the energization of the brake relay 9 can be stopped.

〔Effect of the invention〕

According to the present invention, a highly safe variable speed hoist and a control method thereof can be obtained.

[Brief explanation of the drawing]

Figure 1 is a time chart of the variable speed hoist of the present invention, Figure 2 is a circuit diagram of the same hoist, and Figures 3 to 5 are time charts of the same hoist at different failures. be. 1... Electric motor, 2... Inverter, 3... AC power supply, 4... Push button switch, 5... Low speed relay, 6
...High-speed relay 7...First solid state relay, 8...Second solid state relay, 9...
Brake relay 10... Control relay 11... Brake. Figure 3 Tower 50

Claims (1)

[Scope of Claims] 1. In a variable speed hoisting machine in which a hoisting motor is connected to an AC power source via an inverter and a brake for the motor is controlled by an output signal of the inverter, the problem occurs when the inverter is started. A variable speed hoisting machine, characterized in that the electric motor brake is controlled in a state where both an output signal and an output signal generated when starting the hoisting machine are turned on. 2. In a variable speed hoisting machine in which a hoisting motor is connected to an AC power supply via an inverter and a brake for the motor is controlled by an output signal of the inverter, two output signals generated when the inverter starts operating are A variable speed hoist characterized in that the electric motor brake is controlled in an on state. 3. In a variable speed hoisting machine in which a hoisting motor is connected to an AC power supply via an inverter and a brake for the motor is controlled by an output signal of the inverter, the output signal generated when the inverter is started and the low speed frequency The variable speed hoist is characterized in that the electric motor brake is controlled in a state in which both the output signal generated when the motor brake is turned on and the output signal generated when 4. In a variable speed hoisting machine in which a hoisting motor is connected to an AC power source via an inverter and a brake for the motor is controlled by an output signal of the inverter, a RUN generating an on signal is generated by starting the inverter. A terminal is provided on the inverter, an AR terminal is provided on the inverter that generates an ON signal when a low speed frequency is reached after starting the inverter, and a light emitting element of the first solid state relay is provided between the RUN terminal and the DC power supply terminal. A light emitting element of a second solid state relay is connected between the AR terminal and the DC power supply terminal, a light receiving element of both the light emitting elements is connected in series to a control relay, and the control relay A variable speed hoist characterized in that the brake is controlled. 5. In claim 4, a first stage contact of the push button switch and a low speed relay are connected in series, a second stage contact of the push button switch and a high speed relay are connected in series,
The low speed relay turns on the L terminal of the inverter.
OFF control, and the H of the inverter is controlled by the high speed relay.
The terminals are controlled on and off, the contacts of the low-speed relay and the control relay are connected in parallel with the light receiving element of the second solid state relay, and the contacts of the control relay and the brake relay are connected in series. A variable speed hoist, characterized in that the brake is connected to the brake relay and the brake is controlled by the brake relay. 6. The variable speed hoisting machine according to claim 5, characterized in that a contact point of a low speed relay is connected in series with the contact point of the brake relay and the control relay. 7. A method for controlling a variable speed hoisting machine in which a hoisting motor is connected to an AC power supply via an inverter, and a brake for the motor is controlled when an ON signal is generated in an output signal of the inverter, wherein the inverter is operated. A method for controlling a variable speed hoist, characterized in that the braking of the electric motor brake is released when two output signals generated when starting the motor are turned on.