JPH0753180A - Inverter hoist - Google Patents

Abstract

PURPOSE:To provide an inverter hoist with which the reduction of constitution parts, dimension, and cost, and the simplification of maintenance can be achieved, by carrying out the operation speed selection corresponding to the load and the overload detection according to the input electric current value of an electric motor. CONSTITUTION:An inverter device 3 which is provided with the function for transmitting the information of the input electric current of an electric motor 10 to a control part 14 is mounted on an inverter hoist 15, and a control system which can carry out the operation speed selection corresponding to the load and the overload detection, according to the information of the input electric current of the electric motor 10 which is supplied from the inverter device 3 is installed. Further, the information of the input electric current of the electric motor 10 is taken into a microcomputer part 12 in a control part through an electric current sensor 7 and a calculation part 6 which are installed in the inverter device 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, as a device for variably controlling the rotation speed of an electric motor, is equipped with an inverter device having a function of transmitting information on an electric motor input current to a control unit, so as to operate in accordance with a load. The present invention relates to an inverter hoist that performs speed selection and overload detection.

[0002]

2. Description of the Related Art As a known example of a conventional inverter hoist having a function of selecting an operating speed according to a load, Japanese Utility Model Laid-Open No. 52-170207 can be cited, but in order to clarify the gist of the present invention. , Jitsukai Sho 52-17020
A conventional general inverter hoist that can be inferred from Japanese Patent Publication No. 7 will be described with reference to FIGS.

FIG. 2 shows the structure of a conventional inverter hoist having a function of selecting an operating speed according to a load.

When an operation command for hoisting or hoisting a suspended load is given from the operation input device 9, the signal is taken into the microcomputer section 12 in the control section.

In the microcomputer section 12 in the control section, in order to determine the load of the suspended load, firstly, the electric motor 10 is set at the electric motor rotation frequency f shown in FIG. A command is given to the inverter device calculation unit 6 and the brake device 11 so that the constant speed operation is performed for a certain time.

As described above, the constant speed operation at the electric motor rotation frequency f for a certain period of time has a proportional relationship between the input current value of the electric motor 10 and the load of the suspended load at the electric motor rotation frequency f, as shown in FIG. If the input current value of the electric motor 10 is obtained in this state, it is possible to determine the load of the suspended load based on the value of the input current.

In the inverter device 3, the operation command from the microcomputer unit 12 in the control unit and the current value input to the electric motor 10 are sent to the calculation unit 6 via the current sensor (A) 7 in the inverter device and the current detection unit 8. By fetching and performing comparison calculation, the optimum inverter output current value for the operation command is determined, and the rotation of the electric motor 10 is controlled via the drive unit 5 and the main circuit unit 4.

When an operation command is given from the operation input device 9, the inverter output current flows from the inverter device 3 as described above, and at the same time, the microcomputer unit 12 in the control unit releases the brake device 11 via the drive unit 13 in the control unit. Then, the electric motor 10 is started.

On the other hand, the input current value of the electric motor 10 is detected by the current conversion section 16 via the current sensor (B) 17, converted from AC current to DC voltage, and is constantly taken in the microcomputer section 12 in the control section.

In the control section microcomputer section 12, the electric motor 10
Is a DC input voltage-converted input current of the electric motor 10 during constant-speed operation for a certain period of time at a motor rotation frequency f in which the ratio characteristic of the electric motor input current-load ratio to the rated load has a proportional relationship. The value signal is A / D converted and the load is determined.

Then, the microcomputer section 1 in the control section is previously prepared.
The operation speed corresponding to the load is determined by performing a series of control such as selecting the operation speed corresponding to the load stored in 2 and instructing the inverter device 3 to perform the selected speed operation.

When the hoisting operation is stopped or the hoisting operation is performed, regenerative energy is generated in the electric motor 10. The regenerative resistance device 5 is attached to consume the regenerative energy at this time by heat conversion.

Also, regarding overload detection of a suspended load, as in the case of selecting the operating speed according to the load, the motor 10 is driven at the motor rotation frequency f in which the input current value of the motor 10 and the load of the suspended load are in a proportional relationship. By obtaining the input current value of the above, the microcomputer unit 12 in the control unit detects the overload of the suspended load.

Incidentally, Japanese Patent Application Laid-Open No. 4-244798 entitled "AC Motor Control Device" discloses a crane device equipped with an inverter device having a function of transmitting information on an input current of the motor to a control unit. Are described in.

However, in this known example, the stop brake provided in the electric motor is controlled by the torque signal by the function of transmitting the information (torque signal) of the input current of the electric motor, which is provided in the inverter device, to the control unit, and the function of the electric motor is controlled. Only the case where the phenomenon of the drop of the suspended load that occurs at the time of starting or stopping can be effectively prevented is described.

On the other hand, in the present invention, the information (torque signal) of the input current of the electric motor provided in the inverter device.
Is transmitted to the control unit, the operating speed is selected and the overload is detected according to the load according to the input current value of the electric motor.

[0017]

As described above, in the conventional inverter hoist that selects the operating speed according to the load, the inverter device does not have the function of transmitting the information of the input current of the electric motor to the control unit. , In order to fetch the input current value of the motor for operating speed selection and overload detection into the microcomputer part in the control part, select the operating speed separately from the current sensor provided for inverter processing in the inverter device. , It had to be taken in via the current sensor and current converter provided to detect overload.

The object of the present invention is to take in the information of the input current of the electric motor to the microcomputer part in the control part via the current sensor and the arithmetic part provided in the inverter device, and to operate the speed corresponding to the load by the input current value of the electric motor. An object of the present invention is to provide an inverter hoist with which the number of components is reduced, the size thereof is reduced, the cost is reduced, and the maintenance is simplified by performing selection and overload detection.

[0019]

In order to achieve the above-mentioned object, according to the present invention, an inverter device having a function of transmitting information on an input current of an electric motor to a control unit is mounted on an inverter hoist, and the electric motor from the inverter device is installed. Based on the input current information, the control system that can select the operating speed according to the load and detect the overload is provided.

[0020]

By mounting the inverter device having the function of transmitting the information of the input current of the electric motor to the outside, it is possible to reduce the number of components of the inverter hoist, thereby reducing the size, lowering the cost and simplifying the maintenance.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.

FIG. 1 shows the overall construction of an inverter hoist having a function of selecting an operating speed according to the load in this embodiment, and FIG. 4 shows a process of generating an inverter output pulse signal.

In FIG. 1, reference numeral 10 denotes an electric motor, and an inverter hoist 1 is provided by an inverter device 3 having a function of transmitting information on an input current of the electric motor 10 to a control unit 14.
The motor rotation speed of No. 5 is varied, and the hoisting and hoisting operating speeds are continuously varied from the speed corresponding to the commercial frequency of 60 Hz to the speed corresponding to 120 Hz according to the load of the suspended load, and the operating speed according to the load. Select.

When an operation command for hoisting or hoisting a suspended load is given from the operation input device 9, the microcomputer section 12 in the control section takes in the signal and distinguishes hoisting, hoisting, low speed and high speed operation.

When the low speed operation is instructed regardless of the hoisting or the hoisting operation, the operation command from the microcomputer unit 12 in the control unit and the current value input to the electric motor 10 are supplied to the inverter device 3 by this operation command. Inverter current sensor (A) 7 and current detection unit 8 are used to take in the calculation unit 6,
By performing the comparison calculation, the optimum inverter output current value for the operation command is determined, and the rotation of the electric motor 10 is controlled via the drive unit 5 and the main circuit unit 4.

At the same time, the microcomputer unit 1 in the control unit
2 releases the brake device 11 via the drive unit 13 in the control unit, so that the electric motor 10 is driven.

In this way, the inverter device 3 operates in response to the operating speed command from the microcomputer section 12 in the control section.
The rotational speed of 0 is continuously changed to the instructed operating speed.

The operation speed selection according to the load is performed when the high speed operation is instructed regardless of the hoisting or the hoisting operation.

In the case of the high speed operation, unlike the case of the low speed operation, in order to determine the load, first, in order to detect the input current value of the electric motor 10 proportional to the load of the suspended load, the electric motor rotation frequency f is set for a fixed time. Drive at high speed.

As in the conventional case, the microcomputer section 12 in the control section first determines the electric motor 10 for a certain period of time at the electric motor rotation frequency f at which the ratio of load ratio to electric motor input current-rated load shown in FIG. 3 is proportional. A command is given to the inverter device arithmetic unit 6 and to the brake device 11 so as to perform high speed operation. By this command, an inverter output current flows from the inverter device 3, and at the same time, the microcomputer unit 1 in the control unit
In No. 2, the brake device 11 is released via the drive unit 13 in the control unit, so that the electric motor 10 is started and the constant speed operation is performed at the electric motor rotation frequency f for a fixed time.

On the other hand, the input current of the electric motor 10 is taken into the inverter device current detection section 8 through the current sensor a7 and converted into a DC voltage.

Subsequently, this DC voltage value is taken in by the operation unit 6 in the inverter device, A / D converted and converted into a digital value.

The in-inverter arithmetic unit 6 determines the inverter output current by comparing and operating with the operation command from the in-control unit microcomputer unit 12 based on this digital value.

At the same time, the in-inverter arithmetic unit 6 generates a pulse signal having information proportional to the load as shown in FIG. 4 and transmits it to the in-control unit microcomputer unit 12.

The pulse signal will be described. For example, if the input current of the electric motor 10 is 150% or more of the rated current capacity of the inverter device 3, the Hi signal is 50% of the rated current capacity for one cycle. 1/3 of one cycle
The Hi portion pulse width and the load are in a proportional relationship such that only the Hi signal is output and the remaining 2/3 outputs the Low signal.

Therefore, the load can be discriminated by measuring the Hi portion of the pulse signal.

The pulse signal generation work from the input current of the electric motor 10 is always performed as long as the power source of the inverter device 3 is ON.

That is, the generated pulse signal is always taken in by the microcomputer section 12 in the control section, and when the pulse signal shown in FIG. While the constant speed operation is performed for a certain time at the frequency f, H of this pulse signal
By measuring and sampling the i part, the hoisting or unwinding load is determined.

When the load discrimination is completed, the microcomputer section 1 in the control section
In 2, the operating speed corresponding to the load, which is stored in the microcomputer 12 in the controller in advance, is selected.

From the load discrimination data, when the load is 0 to 25% of the rated load of the hoist, 120 Hz, and when it is 25 to 50%, 8
An operating speed of 60 Hz is selected at 4 Hz and 50 to 100%, and the instruction is sent to the microcomputer unit 12 in the inverter device.

In the inverter device 3, the rotation speed of the electric motor 10 is continuously changed to the command speed by the operation speed command from the microcomputer part 12 in the control part.

When the hoisting operation is stopped or the hoisting operation is performed, regenerative energy is generated in the electric motor 10. The regenerative resistance device 5 is attached to consume the regenerative energy at this time by heat conversion.

Further, regarding the detection of the overload of the suspended load, as in the case of selecting the operating speed according to the load, the motor rotation frequency f in which the input current value of the electric motor 10 and the load of the suspended load have a proportional relationship, By obtaining a pulse signal proportional to the input current value of the electric motor 10, the microcomputer unit 12 in the control unit detects the overload of the suspended load, and in the case of the overload, the driving operation is stopped.

As described above, according to this embodiment, by mounting the inverter device 3 having the function of transmitting the information of the input current of the electric motor as a pulse signal to the control unit,
Information on the input current of the electric motor 10 can be fetched from the inverter device 3 to obtain an inverter hoist having an operation speed selection function and an overload detection function according to the load.

Further, in this embodiment, by mounting the inverter device 3 having the above-mentioned configuration, a current sensor (B) for detecting the input current value of the electric motor 10 as in the conventional example shown in FIG. ) 17, it is not necessary to provide the current converter 16, and the number of constituent parts can be reduced.

In the present embodiment, the load discrimination and the operating speed selection are performed for each hoisting and unwinding operation. However, the load discriminating operation and the operating speed selection are performed at the time of hoisting, and the selected hoisting load discriminating operating speed data is obtained. It may be stored until the control section determines the next operating speed data for hoisting load determination. That is, the hoisting operation speed data at the time of hoisting is applied to the hoisting operation speed data at the time of hoisting.

Regarding the selection of the operating speed in this embodiment, the number of selectable operating speeds is two or more, and the speed can be freely set.

Further, in the present embodiment, the overload detection is performed during both the hoisting and the hoisting operation in consideration of safety in all usage situations, but it may be performed only during hoisting.

Furthermore, as an on-board inverter, VVV
In addition to the F type (variable voltage variable frequency type) inverter, a sensorless vector control type inverter can be naturally applied as long as it has a function of transmitting information of the input current of the electric motor to the control unit.

[0050]

According to the present invention, the information of the input current of the electric motor is taken into the microcomputer unit in the control unit via the current sensor and the arithmetic unit provided in the inverter device, and the load is determined according to the input current value of the electric motor. By selecting the operating speed and detecting overload, it is possible to reduce the number of components, resulting in downsizing, cost reduction, and simplification of maintenance.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an inverter hoist having a function of selecting an operating speed according to a load and a function of detecting an overload according to the present embodiment.

FIG. 2 is a configuration diagram of a conventional inverter hoist having a function for selecting and selecting an operating speed according to a load and an overload detection function.

FIG. 3 is a diagram showing a ratio characteristic of a load to a motor input current-rated load.

FIG. 4 is a diagram showing a process of generating an inverter output pulse signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main power supply, 2 ... Discharge resistance or regenerative device, 3 ... Inverter device, 4 ... Main circuit, 5 ... Drive part, 6 ... Arithmetic part, 7 ...
Current sensor (A), 8 ... Current detection unit, 9 ... Operation input device, 10 ... Electric motor, 11 ... Brake device, 12 ... Control unit internal microcomputer unit, 13 ... Control unit internal drive unit, 14 ... Control unit,
15 ... Inverter hoist.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Saito 1-1-1, Higashitaga-cho, Hitachi-shi, Ibaraki Living Company Division, Hitachi Ltd.

Claims (2)

[Claims] 1. An operation input device for giving an operation command for moving a suspended load up and down, an electric motor as a power source for moving the suspended load up and down, a brake device for stopping the drive of the electric motor, and an electric motor. A regenerative device for returning the discharge resistance or regenerative current that consumes the regenerative current to the main power supply unit, an inverter device that variably controls the rotation speed of the electric motor, and a control unit that controls the operation input device, the inverter device, and the brake device. In an inverter hoist equipped with, by obtaining the information of the input current of the electric motor from the inverter device having the function of transmitting the information of the input current of the electric motor to the control unit,
An inverter hoist comprising means for selecting an operating speed according to a load of a suspended load in a control unit. 2. The inverter hoist according to claim 1, wherein the control unit detects the overload of the suspended load by obtaining information on the input current of the electric motor from the inverter device.