阅读说明：本技术 一种防止悬臂吊升降变频电机过载控制方法 (Control method for preventing overload of variable frequency motor lifted by cantilever crane ) 是由 叶光平 于 2020-11-09 设计创作，主要内容包括：本发明公开了一种防止悬臂吊升降变频电机过载控制方法,属于电气传动控制技术领域。本发明防止悬臂吊升降变频电机过载控制程序由两个控制单元组成,即功能块FXDGC11～FXDGC19构成悬臂吊升降变频电机传动系统故障判定单元；功能块FXDGC01～FXDGC10构成悬臂吊升降速度控制单元。本发明操作简便,基于悬臂吊的工作特性,可用于各种悬臂吊升降变频电机的控制,很好地解决了悬臂吊升降变频电机频繁短时过载保护所存在的问题。(The invention discloses a control method for preventing overload of a variable frequency motor lifted by a cantilever crane, and belongs to the technical field of electric transmission control. The control program for preventing the overload of the cantilever crane lifting variable frequency motor consists of two control units, namely a fault judgment unit of a cantilever crane lifting variable frequency motor transmission system consisting of functional blocks FXDGC 11-FXDGC 19; the function blocks FXDGC 01-FXDGC 10 form a cantilever hoisting and descending speed control unit. The invention has simple and convenient operation, can be used for controlling various lifting variable frequency motors of the cantilever crane based on the working characteristics of the cantilever crane, and well solves the problem of frequent short-time overload protection of the lifting variable frequency motors of the cantilever crane.)

1. A control method for preventing overload of a cantilever crane lifting variable frequency motor is characterized by comprising the following steps: the control program for preventing the overload of the cantilever crane lifting variable frequency motor consists of two control units, namely a fault judgment unit of a transmission system of the cantilever crane lifting variable frequency motor is formed by functional blocks FXDGC 11-FXDGC 19; the function blocks FXDGC 01-FXDGC 10 form a cantilever hoisting and descending speed control unit; the control method for preventing the overload of the cantilever crane lifting variable frequency motor is a control program for preventing the overload of the cantilever crane lifting variable frequency motor, and comprises the following steps of:

a1, regarding a cantilever crane lifting variable frequency motor transmission system fault judging unit, considering that the starting current of a cantilever crane lifting variable frequency motor is usually less than or equal to the motor current amplitude limiting value of a frequency converter and the time of the starting process is less than 3 seconds, in the unit, the continuous locked-rotor current monitoring value of the cantilever crane lifting variable frequency motor is set as 120% of the rated current of the motor, when the actual current absolute value of the cantilever crane lifting variable frequency motor exceeds Ikz and the time of the starting process is more than 4 seconds, the output end Q of a function block FXDGC15 and FXDGC16 in the unit is changed from '0' state to '1' state; in addition, considering that the lifting steady-state current of the cantilever crane lifting variable-frequency motor is usually less than or equal to the rated current of the motor, on the basis of the unit, the continuous overload current monitoring value of the cantilever crane lifting variable-frequency motor is set to be 110% of the rated current of the motor, and when the actual current absolute value of the cantilever crane lifting variable-frequency motor exceeds Icz and the duration time reaches more than 100 seconds, the output end Q of the functional block FXDGC13 and FXDGC16 in the unit changes from a '0' state to a '1' state; as can be seen by the unit control routine, when the output Q of the function block FXDGC16 in the unit changes from '0' state to '1' state, the output Q of the function block FXDGC17 in the unit will generate a '1' pulse with a width of 30 seconds; therefore, when the unit judges that the cantilever crane lifting variable frequency motor has abnormal locked rotor or abnormal overload, the unit sends a cantilever crane lifting variable frequency motor transmission system fault signal with the duration of 30 seconds to the cantilever crane lifting speed control unit through a function block FXDGC19 in the unit, so that the cantilever crane lifting variable frequency motor can obtain 30-second pause heat dissipation time after the cantilever crane lifting variable frequency motor has abnormal locked rotor or overload, and the damage of the cantilever crane variable frequency motor due to frequent short-time overload can be effectively avoided;

a2, for a cantilever crane lifting speed control unit, when a cantilever crane lifting variable frequency motor transmission device has no fault and a variable frequency motor has no locked rotation or overload fault, the input end I2 of a functional block FXDGC01, FXDGC03, FXDGC05 and FXDGC07 in the cantilever crane lifting speed control unit is in a '1' state, so that when a cantilever crane operator sends a cantilever crane fast/slow lifting or descending instruction, a fast output end of the functional blocks FXDGC01, FXDGC03, FXDGC05 and FXDGC07 is in the '1' state, and the unit outputs a cantilever crane lifting variable frequency motor transmission frequency converter running enabling signal through the functional block FXC 10; meanwhile, the unit outputs corresponding cantilever crane fast/slow ascending or descending speed reference values to a cantilever crane ascending and descending variable frequency motor transmission frequency converter through functional blocks FXDGC02, FXDGC04, FXDGC06 and FXDGC 08; therefore, the cantilever crane starts to perform fast/slow lifting operation, however, if the cantilever crane lifting variable frequency motor has stalling or overload faults in the process of the cantilever crane lifting operation, the output end Q of the functional blocks FXDGC01, FXDGC03, FXDGC05 and FXDGC07 in the unit is in a '0' state, and therefore the unit blocks the operation enabling signal and the speed reference value of the transmission frequency converter of the cantilever crane lifting variable frequency motor, so that the cantilever crane lifting variable frequency motor is in a pause heat radiation state.

Technical Field

The invention relates to the technical field of electric transmission control, in particular to a control method for preventing an overload of a variable frequency motor lifted by a cantilever crane.

Background

For the cantilever crane lifting variable frequency motor, the power supply frequency converter of the cantilever crane lifting variable frequency motor usually performs current amplitude limiting (or output torque amplitude limiting) and overcurrent (or motor short circuit) protection on the motor based on the motor current, but the current amplitude limiting and overcurrent protection of the motor cannot realize frequent short-time overload protection of the motor. Based on this, when the cantilever crane lifting variable frequency motor is frequently in an overload or even locked-rotor state due to complex lifting working conditions or improper use, under the condition, the cantilever crane lifting variable frequency motor may be damaged due to frequent short-time overload and no protection.

Disclosure of Invention

The invention aims to provide a control method for preventing overload of a lifting variable frequency motor of a cantilever crane, which can be used for controlling various lifting variable frequency motors of the cantilever crane based on the working characteristics of the cantilever crane and solves the problems of frequent short-time overload protection of the lifting variable frequency motor of the cantilever crane.

In order to achieve the purpose, the invention provides the following technical scheme: a control method for preventing the overload of a cantilever crane lifting variable frequency motor comprises a control program for preventing the overload of the cantilever crane lifting variable frequency motor, namely a fault judgment unit of a cantilever crane lifting variable frequency motor transmission system is formed by functional blocks FXDGC 11-FXDGC 19; the function blocks FXDGC 01-FXDGC 10 form a cantilever hoisting and descending speed control unit; the control method for preventing the overload of the cantilever crane lifting variable frequency motor is a control program for preventing the overload of the cantilever crane lifting variable frequency motor, and comprises the following steps of:

a1, regarding a cantilever crane lifting variable frequency motor transmission system fault judging unit, considering that the starting current of a cantilever crane lifting variable frequency motor is usually less than or equal to the motor current amplitude limiting value of a frequency converter and the time of the starting process is less than 3 seconds, in the unit, the continuous locked-rotor current monitoring value of the cantilever crane lifting variable frequency motor is set as 120% of the rated current of the motor, when the actual current absolute value of the cantilever crane lifting variable frequency motor exceeds Ikz and the time of the starting process is more than 4 seconds, the output end Q of a function block FXDGC15 and FXDGC16 in the unit is changed from '0' state to '1' state; in addition, considering that the lifting steady-state current of the cantilever crane lifting variable-frequency motor is usually less than or equal to the rated current of the motor, on the basis of the unit, the continuous overload current monitoring value of the cantilever crane lifting variable-frequency motor is set to be 110% of the rated current of the motor, and when the actual current absolute value of the cantilever crane lifting variable-frequency motor exceeds Icz and the duration time reaches more than 100 seconds, the output end Q of the functional block FXDGC13 and FXDGC16 in the unit changes from a '0' state to a '1' state; as can be seen by the unit control routine, when the output Q of the function block FXDGC16 in the unit changes from '0' state to '1' state, the output Q of the function block FXDGC17 in the unit will generate a '1' pulse with a width of 30 seconds; therefore, when the unit judges that the cantilever crane lifting variable frequency motor has abnormal locked rotor or abnormal overload, the unit sends a cantilever crane lifting variable frequency motor transmission system fault signal with the duration of 30 seconds to the cantilever crane lifting speed control unit through a function block FXDGC19 in the unit, so that the cantilever crane lifting variable frequency motor can obtain 30-second pause heat dissipation time after the cantilever crane lifting variable frequency motor has abnormal locked rotor or overload, and the damage of the cantilever crane variable frequency motor due to frequent short-time overload can be effectively avoided;

a2, for a cantilever crane lifting speed control unit, when a cantilever crane lifting variable frequency motor transmission device has no fault and a variable frequency motor has no locked rotation or overload fault, the input end I2 of a functional block FXDGC01, FXDGC03, FXDGC05 and FXDGC07 in the cantilever crane lifting speed control unit is in a '1' state, so that when a cantilever crane operator sends a cantilever crane fast/slow lifting or descending instruction, a fast output end of the functional blocks FXDGC01, FXDGC03, FXDGC05 and FXDGC07 is in the '1' state, and the unit outputs a cantilever crane lifting variable frequency motor transmission frequency converter running enabling signal through the functional block FXC 10; meanwhile, the unit outputs corresponding cantilever crane fast/slow ascending or descending speed reference values to a cantilever crane ascending and descending variable frequency motor transmission frequency converter through functional blocks FXDGC02, FXDGC04, FXDGC06 and FXDGC 08; therefore, the cantilever crane starts to perform fast/slow lifting operation, however, if the cantilever crane lifting variable frequency motor has stalling or overload faults in the process of the cantilever crane lifting operation, the output end Q of the functional blocks FXDGC01, FXDGC03, FXDGC05 and FXDGC07 in the unit is in a '0' state, and therefore the unit blocks the operation enabling signal and the speed reference value of the transmission frequency converter of the cantilever crane lifting variable frequency motor, so that the cantilever crane lifting variable frequency motor is in a pause heat radiation state.

Compared with the prior art, the invention has the beneficial effects that:

the control method for preventing the overload of the cantilever crane lifting variable frequency motor is simple and convenient to operate, can be used for controlling various cantilever crane lifting variable frequency motors based on the working characteristics of the cantilever crane, and well solves the problem of frequent short-time overload protection of the cantilever crane lifting variable frequency motor.

Drawings

Fig. 1 is a control program configuration diagram of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In fig. 1, NSW is a "digital input switch" function block, and when I is equal to '1', Y is equal to X2, and when I is equal to '0', Y is equal to X1; NCM is the "numerical comparison" function block, QU is ' 1 ' when X1 > X2, ' QE is ' 1 ' when X1 ═ X2, and QL is ' 1 ' when X1 < X2; AVA is an absolute value forming function block; ADD is an adder function block; PDE is a 'leading edge delay' functional block; OR is an OR gate; AND is an AND gate; NOT is a NOT gate. Icz is a continuous overload current monitoring value of the cantilever crane lifting variable frequency motor; ikz is the locked-rotor current monitoring value of the cantilever crane lifting variable frequency motor.

According to the control method for preventing the overload of the cantilever crane lifting variable frequency motor, a control program for preventing the overload of the cantilever crane lifting variable frequency motor is composed of two control units, namely a fault judgment unit of a transmission system of the cantilever crane lifting variable frequency motor is composed of functional blocks FXDGC 11-FXDGC 19; the function blocks FXDGC 01-FXDGC 10 form a cantilever hoisting and descending speed control unit; the control method for preventing the overload of the cantilever crane lifting variable frequency motor is a control program for preventing the overload of the cantilever crane lifting variable frequency motor, and comprises the following steps of:

a1, for a failure determination unit of a transmission system of a cantilever crane lifting variable frequency motor, considering that the starting (or braking) current of the cantilever crane lifting variable frequency motor is usually less than or equal to a motor current amplitude limiting value (150% motor rated current) of a frequency converter and the time for the starting (or braking) process is less than 3 seconds, in the unit, a continuous locked-rotor current monitoring value (Ikz) of the cantilever crane lifting variable frequency motor is set as 120% motor rated current, and when the actual current absolute value (namely the output value of the output end Y of a function block FXDGC11 in the unit) of the cantilever crane lifting variable frequency motor exceeds Ikz and the time for duration reaches more than 4 seconds, the output end Q of the function block FXDGC15 and FXDGC16 in the unit changes from a '0' state to a '1' state; in addition, considering that the crane hoist inverter motor normally has a steady-state hoist current less than or equal to the motor rated current, on the basis of this, in the unit, the crane hoist inverter motor continuous overload current monitoring value (Icz) is set to 110% of the motor rated current, when the absolute value of the actual current of the crane hoist inverter motor (i.e. the output value of the output terminal Y of the functional block FXDGC11 in the unit) exceeds Icz and the duration time reaches more than 100 seconds, the output terminals Q of the functional blocks FXDGC13 and FXDGC16 in the unit change from '0' state to '1' state; as can be seen by the unit control routine, when the output Q of the function block FXDGC16 in the unit changes from '0' state to '1' state, the output Q of the function block FXDGC17 in the unit will generate a '1' pulse with a width of 30 seconds; therefore, when the unit judges that the cantilever crane lifting variable frequency motor has abnormal locked-rotor (namely the motor current exceeds 120% of the motor rated current and the duration time reaches the set monitoring time) or abnormal overload (namely the motor current exceeds 110% of the motor rated current and the duration time reaches the set monitoring time), the unit sends a cantilever crane lifting variable frequency motor transmission system fault signal with the duration time of 30 seconds to the cantilever crane lifting speed control unit through a function block FXDGC19 in the unit, so that the cantilever crane lifting variable frequency motor can obtain 30-second pause heat dissipation time after the abnormal locked-rotor or overload occurs, and the damage of the cantilever crane variable frequency motor due to frequent short-time overload can be effectively avoided;

a2, for a cantilever crane lifting speed control unit, when a cantilever crane lifting variable frequency motor transmission device has no fault and a variable frequency motor has no locked rotation or overload fault, the input end I2 of a functional block FXDGC01, FXDGC03, FXDGC05 and FXDGC07 in the cantilever crane lifting speed control unit is in a '1' state, so that when a cantilever crane operator sends a cantilever crane fast/slow lifting or descending instruction, a fast output end of the functional blocks FXDGC01, FXDGC03, FXDGC05 and FXDGC07 is in the '1' state, and the unit outputs a cantilever crane lifting variable frequency motor transmission frequency converter running enabling signal through the functional block FXC 10; meanwhile, the unit outputs corresponding cantilever crane fast/slow ascending or descending speed reference values to a cantilever crane ascending and descending variable frequency motor transmission frequency converter through functional blocks FXDGC02, FXDGC04, FXDGC06 and FXDGC 08; therefore, the cantilever crane starts to perform fast/slow lifting operation, however, if the cantilever crane lifting variable frequency motor has stalling or overload faults in the process of the cantilever crane lifting operation, the output end Q of the functional blocks FXDGC01, FXDGC03, FXDGC05 and FXDGC07 in the unit is in a '0' state, and therefore the unit blocks the operation enabling signal and the speed reference value of the transmission frequency converter of the cantilever crane lifting variable frequency motor, so that the cantilever crane lifting variable frequency motor is in a pause heat radiation state.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.