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A control method of a constant force jib crane using a vector variable voltage variable frequency frequency converter as a power source

A technology of variable voltage, variable frequency, and control method, which is applied in the direction of load hanging components, transportation, and packaging, etc., and can solve problems such as measurement difficulties, inaccurate results, measurement being affected by installation location and method, and lack of automatic safety control.

Inactive Publication Date: 2016-08-24
CHENGDU QIANQIU TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, all the sensors are installed externally, so the hardware cost, installation method, and measurement accuracy have brought a series of problems; there are obvious sensor additional hardware costs are high, installation is difficult, and the measurement is affected by the installation location. The method and method have great influence, resulting in measurement difficulties, inaccurate results and many disadvantages of the lack of automatic safety control

Method used

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  • A control method of a constant force jib crane using a vector variable voltage variable frequency frequency converter as a power source
  • A control method of a constant force jib crane using a vector variable voltage variable frequency frequency converter as a power source
  • A control method of a constant force jib crane using a vector variable voltage variable frequency frequency converter as a power source

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0101] The control method of the constant-arm crane using the vector variable voltage frequency converter as the power source of this embodiment. It includes the following steps:

[0102] S1: Hoisting motor vector variable voltage and frequency conversion (VT-VVVF is the same below) The inverter controls the hoisting motor to run and start at the starting frequency fqd:

[0103] In this example, the VT-VVVF frequency converter controls the lifting motor according to the starting frequency of 0.5 Hz. The inverter selected in this example automatically selects the startup item;

[0104] S2: After the lifting motor is started, gradually increase the output frequency of the inverter to the measurement frequency f. The principle of f is to ensure no overload and stable lifting at the lowest possible frequency. In this case, 15Hz; measure the VT-VVVF inverter of the lifting motor Rectified output DC voltage U d And DC current I d , Which corresponds to DC power P d = U d ×I d When the fl...

Embodiment 2

[0153] The difference between this embodiment and embodiment 1 is that the slip rate of the hoisting motor adopts the corrected slip rate.

[0154] According to: S=S n ×(P d / P dn )×(f 0 / f)………………(3-5);

[0155] or

[0156] The system operating condition parameters of this embodiment are the same as in embodiment 1:

[0157] When the actual VT-VVVF inverter rectified output DC power P d =34.57kW,

[0158] Uncorrected rated slip S n That is, the calculation of rated slip:

[0159] S n =(n 0 -nN) / n 0 =(750-722) / 750=0.0373;

[0160] Slip after correction:

[0161]

[0162] Using the corrected slip ratio S to calculate the output speed of the hoisting motor is: n N = N 0 -S×n 0 =750-0.03712×750=722.16r / min. In actual measurement, the hoisting motor speed is 723r / min. Using the corrected slip rate S is smaller than using the uncorrected rated slip rate Sn to calculate the output speed of the hoisting motor and the actual measured speed error is smaller; it is concluded that the former is us...

Embodiment 3

[0196] The control method of the constant-arm crane using the vector variable voltage frequency converter as the power source of this embodiment. It includes the following steps:

[0197] S1: The hoisting motor vector variable voltage frequency converter controls the hoisting motor to run and start at the starting frequency fqd;

[0198] In this example, the VT-VVVF frequency converter controls the lifting motor according to the starting frequency of 5Hz. The starting frequency is determined by the selected inverter.

[0199] S2: After the lifting motor starts, measure the rectified output DC voltage U of the lifting motor VT-VVVF inverter d And DC current I d , P d = U d ×I d ; When the fluctuation range is less than 10% within 2 seconds, the measurement record VT-VVVF change

[0200] Frequency converter P d And its output frequency f, calculate the hoisting mechanism motor output torque Tfz:

[0201] Tfz=Kdj×Kdx×Kjs×P d / f=Kdj×Kdx×Kjs×(U d ×I d ) / f.....(2-2);

[0202] In this embodim...

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Abstract

The invention belongs to the field of crane control, and particularly relates to a control method for a constant-moment-arm crane taking a vector variable-voltage variable-frequency frequency converter as a power supply. The control method comprises: measuring the output direct-current power and the output frequency of the frequency converter after a lifting variable frequency motor is started and is stable; indirectly measuring the torque of a lifting weight load; taking the torque and the rated power of the lifting motor as limited conditions to obtain the maximum operation frequency of the lifting motor; and determining the operation frequency of the lifting motor via speed control shifts. According to the invention, the crane system not only can work in a rated torque, but also can work in a rated power, so that double purposes of safety assurance and improved frequency are achieved. According to the invention, inner parameters of the frequency converter are measured; a sensor in a conventional crane system is omitted; the measurement accuracy is improved; and the system complexity and cost are reduced. The crane system is simple, accurate, high-efficient, and reliable.

Description

Technical field [0001] The invention belongs to the field of crane control, and in particular relates to a control method of a constant boom crane using a vector variable voltage frequency converter as a power source. Background technique [0002] With technological progress and market requirements, in recent years, frequency conversion technology has been increasingly introduced into crane systems. As its power source, it has advanced technology, easy control, wide speed range, stable work, simple structure, and maintenance costs. The advantages of low and high degree of integration have gradually become the most important power source for crane systems. Crane is a kind of mechanical equipment commonly used in modern production. Different use occasions have different use requirements. Generally, cranes that can be adapted to these occasions are designed and manufactured for different use occasions. During the operation of the crane, if the lifting arm of the crane system does n...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B66C13/22
CPCB66C13/22
Inventor 聂剑王友军税蔚栋高良儒唐莉廖多义
Owner CHENGDU QIANQIU TECH
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