Driving device for logistic transfer system

Abstract

The present invention relates to a driving device for a logistics transfer system equipped with a PLC (programmable logic controller) that outputs a single motion signal and an AC motor. The driving device of the present invention includes a signal converter that receives a motion signal output from the PLC and outputs a signal that controls the rotational speed of the AC motor according to the driving time of the AC motor, and an inverter that outputs a driving signal that drives the AC motor according to the control signal output from the signal converter. The present invention can be easily applied to a driving device of an existing logistics transfer system equipped with a PLC that outputs a single motion signal, and can significantly reduce noise and vibration at a low cost.

Description

Technology Field

[0001] The present invention relates to a driving device for a logistics transfer system, and more particularly to a driving device capable of reducing vibration in a logistics transfer system equipped with a PLC (programmable logic controller) and an AC motor. Background Technology

[0003] Drive systems consisting of a PLC (programmable logic controller), inverter, and AC motor are widely used in logistics transfer systems, such as lifts, that transport heavy masses like automobiles, for the purpose of cost reduction. However, these drive systems present problems such as difficulty in controlling the acceleration and deceleration of AC motors, resulting in vibration (and noise) during operation or stopping in the field, reduced positional accuracy, and shortened fatigue life. Prior art literature

[0005] 1. Korean Registered Patent No. 10-1047373 (Cargo handling control system in a logistics system and control method thereof) 2. Korean Registered Patent No. 10-1254598 (Method for verifying the interlock function of a PLC control program using an SMV) The problem to be solved

[0006] Accordingly, the present invention has one objective of reducing vibration in a drive device of a logistics transfer system equipped with a PLC that outputs a single motion signal.

[0007] In addition, the present invention has another objective of increasing positional accuracy in a logistics transfer system equipped with a PLC that outputs a single motion signal.

[0008] In addition, another objective of the present invention is to extend the fatigue life of a logistics transfer system equipped with a PLC that outputs a single motion signal. means of solving the problem

[0010] In order to achieve the aforementioned objective, the present invention, in one aspect, comprises a driving device for a logistics transfer system having a PLC (programmable logic controller) that outputs a motion signal and an AC motor, the driving device comprising: a signal conversion unit that receives the motion signal output from the PLC and outputs a signal that controls the rotational speed of the AC motor according to the driving time of the AC motor; and an inverter unit that outputs a driving signal that drives the AC motor according to the control signal output from the signal conversion unit.

[0011] Preferably, the signal converter has a bypass mode that receives the motion signal and outputs it directly to the inverter unit.

[0012] Preferably, the signal converter sets the intervals between rotational speeds differently while maintaining the holding time for each rotational speed constant. Additionally, the signal converter sets the holding time for each rotational speed differently while maintaining the intervals between rotational speeds constant. Effects of the invention

[0014] The present invention can be easily applied to a drive device of an existing logistics transfer system equipped with a PLC that outputs a single motion signal, and can significantly reduce noise and vibration at a low cost. Furthermore, by reducing noise and vibration in the logistics transfer system, the present invention has the effect of increasing the positional accuracy of the logistics transfer system and extending its fatigue life. Brief explanation of the drawing

[0016] FIG. 1 is a configuration diagram of a driving device of a logistics transfer system according to one embodiment of the present invention. Figure 2 is a diagram illustrating the occurrence of noise and vibration in a logistics transfer system prior to the application of the present invention. FIG. 3(a) illustrates a driving signal provided to an AC motor in a driving device prior to the application of the present invention, and FIG. 3(b) illustrates a driving signal provided to an AC motor in a driving device to which an embodiment of the present invention is applied. FIG. 4 is a diagram illustrating the influence of a signal conversion unit and an inverter unit on a driving signal in a driving device according to an embodiment of the present invention. FIG. 5 illustrates various driving signals generated in a driving device according to an embodiment of the present invention. FIG. 6 is a diagram illustrating the vibration reduction effect according to one embodiment of the present invention. Specific details for implementing the invention

[0017] To fully understand the present invention, preferred embodiments of the invention are described with reference to the accompanying drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described in detail below. These embodiments are provided to more completely explain the present invention to those with average knowledge in the art. Accordingly, the shapes of elements in the drawings may be exaggerated to emphasize clearer explanations. It should be noted that in each drawing, identical components may be depicted with the same reference numeral. Detailed descriptions of known functions and configurations that are deemed to unnecessarily obscure the essence of the present invention are omitted.

[0018] FIG. 1 is a configuration diagram of a drive unit (100) of a logistics transfer system according to one embodiment of the present invention. As shown, the drive unit (100) of the logistics transfer system comprises a PLC (102), a signal converter (104), an inverter (106), and an AC motor (108).

[0019] The PLC (102) is a highly autonomous control device that enables program control by replacing functions such as relays, timers, and counters within the control panel with semiconductor devices such as ICs and transistors, and by adding numerical calculation functions to basic sequence control functions. In a drive device (100) applied to a conventional logistics transfer system, the PLC (102) outputs a motion signal that causes the AC motor (108) to have a single rotational speed during the driving time.

[0020] The signal converter (104) receives a motion signal from the PLC (102) and outputs a control signal to the inverter (106). The control signal specifies the rotational speed of the AC motor (108) and the holding time for each rotational speed. The signal converter (104) is equipped with a conversion mode (110) and a bypass mode (112). In the conversion mode (110), a control signal is generated such that the rotational speed and holding time of the AC motor (108) differ from the motion signal. In the bypass mode (112), the motion signal of the PLC (102) is transmitted as is and provided to the inverter unit (106) as a control signal. The bypass mode (112) is configured to be activated when the conversion mode (110) is unnecessary or when a problem occurs in the signal converter (104).

[0021] The inverter unit (106) converts the DC signal provided to the inverter unit (106) into an AC signal and provides it to the AC motor (108) according to the rotational speed and holding time specified by the control signal input from the signal conversion unit (104).

[0022] FIG. 2 illustrates the occurrence of noise and vibration in a logistics transfer system prior to the application of the present invention. FIG. 2(a) shows a case where vibration (and noise) occurs due to the sudden stopping of a mass in the vertical direction in a lift system, and FIG. 2(b) shows a case where vibration (and noise) occurs due to the sudden stopping of a mass in the horizontal direction in a conveyor system. Such vibration reduces positional accuracy in the logistics transfer system and shortens fatigue life.

[0023] FIG. 3(a) illustrates a driving signal provided to an AC motor (108) in a driving device prior to the application of the present invention, and FIG. 3(b) illustrates a driving signal provided to an AC motor (108) in a driving device to which an embodiment of the present invention is applied.

[0024] As illustrated in FIG. 3(a), the motion signal generated by the PLC (102) represents only one rotational speed during the driving time of the AC motor (108). Therefore, if the motion signal is provided directly to the inverter unit (106), noise and vibration will occur in the logistics transfer system due to the rapid change in rotational speed of the AC motor (108) during driving. In contrast, as illustrated in FIG. 3(b), if the motion signal generated by the PLC (102) is provided to the signal conversion unit (104), the signal conversion unit (104) causes the inverter unit (106) to output a driving signal that causes the rotational speed of the AC motor (108) to change stepwise according to the driving time in the conversion mode (110). Therefore, noise and vibration generated in the logistics transfer system due to the rapid change in rotational speed during the driving of the AC motor (108) can be reduced.

[0025] FIG. 4 is a diagram illustrating the influence of a signal conversion unit (104) and an inverter unit (106) on a driving signal in a driving device (100) according to one embodiment of the present invention.

[0026] The inverter unit (106) outputs a driving signal corresponding to rotational speeds V1 to V6. The signal conversion unit (104) outputs a control signal such that the driving signal corresponding to rotational speed V1 becomes a holding time T1, the driving signal corresponding to V2 becomes T2, the driving signal corresponding to V4 becomes T3, and the driving signal corresponding to V5 becomes T4.

[0027] FIG. 5 illustrates various driving signals generated in a driving device (100) according to an embodiment of the present invention. As illustrated, the signal converter (104) can generate control signals by setting different intervals between rotational speeds while maintaining a constant holding time for each rotational speed, or by setting different holding times for each rotational speed while maintaining a constant interval between rotational speeds. In this way, the signal converter (104) can effectively reduce vibration while shortening the rotational speed change interval (i.e., increasing the control response speed) by reflecting the characteristics of a logistics transfer system.

[0028] FIG. 6 is a diagram illustrating a vibration reduction effect according to an embodiment of the present invention. FIG. 6(a) is a configuration diagram of a system for testing the vibration reduction effect, and FIG. 6(b) shows experimental data derived from the system of FIG. 6(a). When the amount of change in vibration is defined as in the following Equation 1, it was confirmed that the amount of vibration decreased by 44% when the mass was raised in the Z direction, and decreased by 67% when it was lowered.

[0030]

[0032] The driving device of a logistics transfer system according to one embodiment of the present invention described above is merely illustrative, and those skilled in the art will readily understand that various modifications and equivalent alternative embodiments are possible therefrom. Therefore, it will be readily understood that the present invention is not limited only to the forms mentioned in the above detailed description. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims. Furthermore, the present invention should be understood to include all modifications, equivalents, and substitutions within the spirit and scope of the present invention as defined by the appended claims. Explanation of the symbols

[0034] 100: Driving device of a logistics transfer system 102 : PLC 104: Signal converter 106 : Inverter section 108 : AC motor 110 : Conversion mode 112 : Bypass mode

Claims

Claim 1 A driving device for a logistics transfer system comprising a PLC (programmable logic controller) that outputs a single motion signal and an AC motor, wherein the device includes a signal converter that receives a single motion signal indicating a single target rotational speed during the driving time of the AC motor output by the PLC, and generates and outputs a multi-stage control signal comprising a plurality of intermediate rotational speeds that change stepwise until the AC motor reaches the target rotational speed from a stationary state and a holding time for each intermediate rotational speed, and an inverter that outputs a driving signal for driving the AC motor according to the multi-stage control signal output by the signal converter, wherein the logistics transfer system is a lift system that transports a mass in a vertical direction or a conveyor system that transports a mass in a horizontal direction, and the AC motor is an induction motor that rotates the drive shaft of the lift system or the conveyor system, and wherein the signal converter generates the multi-stage control signal based on the single motion signal to reduce vibration occurring at the start or stop of transport of the lift system or the conveyor system, i) sets the interval between rotational speeds differently while maintaining the holding time for each intermediate rotational speed constant, or ii) the rotational speed A driving device for a logistics transfer system characterized by setting different holding times for each rotational speed while maintaining a constant interval between them. Claim 2 A driving device for a logistics transfer system according to claim 1, wherein the signal conversion unit comprises: a conversion mode that converts the motion signal to generate the multi-stage control signal; and a bypass mode that transmits the motion signal to the inverter unit without converting it, and selectively operates in either the conversion mode or the bypass mode. Claim 3 A driving device for a logistics transfer system according to claim 1, wherein the signal conversion unit, in generating the multi-stage control signal, sets the intermediate rotational speeds and the holding time such that the change in speed over time has a trapezoidal shape or an S-curve shape.

Images