Energy-saving electric control system of large-tonnage European style crane

Abstract

The utility model discloses an energy-saving electric control system for a large-tonnage European-style crane. The energy-saving electric control system comprises a main circuit, an inverter, an energy feedback unit and a frequency converter, the inverter is connected in the main circuit in series and connected with the energy feedback unit in series, the energy feedback unit is connected with the frequency converter in series through a direct-current bus, the main circuit is connected with a lifting motor circuit in series, and the frequency converter is connected with the lifting motor circuit in series. The energy feedback unit is connected in series with a fault control circuit which is connected in series with a first relay and a second relay which are arranged in parallel. According to the utility model, the functions of variable frequency speed regulation and energy feedback to a power grid can be realized, the energy-saving control of variable frequency speed regulation can be realized, the continuous work of the hoisting mechanism can be maintained by utilizing the frequency converter and the standby brake unit when the feedback unit fails, the safety redundancy control function is realized, and the safe, reliable and efficient operation of the hoisting mechanism is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of crane energy feedback circuits, in particular to an energy-saving electric control system for a large-tonnage European-style crane. Background Art

[0002] The concept of European crane was formed in the industry in recent years. Its purpose is to distinguish it from the so-called domestic, Soviet and traditional cranes. In essence, it is a medium-to-high-end gantry crane with the advantages of light weight, compact structure and low energy consumption. The existing European crane has a simple bridge structure design and relatively single function, and the end beam is generally connected to the two ends of the main beam by bolts. With the widespread application of European cranes, the comprehensive requirements for performance, efficiency, load capacity, energy saving, maintenance and other aspects of European cranes are becoming higher and higher.

[0003] The patent with authorization announcement number CN206340982U discloses an energy feedback control device for a construction elevator, including a frequency converter, an active front end AFE, a PLC programmable controller, a motor, a contactor, a power grid, a brake and a status display screen; the frequency converter is connected to the power grid through a contactor, the frequency converter is connected to the motor through a cable, the frequency converter is connected to the active front end AFE through a DC bus, the active front end is connected to the power grid through a contactor, the frequency converter is connected to a PLC programmable controller, and the PLC programmable controller is provided with a status display screen. When the frequency converter fails, it cannot run, lacks safety protection, and needs to be improved. Utility Model Content

[0004] The technical problem to be solved by the utility model is to overcome the existing defects and provide an energy-saving electric control system for large-tonnage European cranes, which can not only realize the functions of variable frequency speed regulation and energy feedback to the power grid, realize energy-saving control of variable frequency speed regulation, but also can use the frequency converter and spare brake unit to maintain the continuous operation of the lifting mechanism when the feedback unit fails. It has a safety redundant control function, realizes safe, reliable and efficient operation of the lifting mechanism, and can effectively solve the problems in the background technology.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: an energy-saving electric control system for a large-tonnage European crane, comprising a main circuit, an inverter, an energy feedback unit and a frequency converter; the inverter is connected in series in the main circuit, the inverter is connected in series with the energy feedback unit, the energy feedback unit is connected in series with the frequency converter through a DC bus, the main circuit is connected in series with a lifting motor circuit, and the frequency converter is connected in series with the lifting motor circuit;

[0006] The energy feedback unit is connected in series with a fault control circuit, and the fault control circuit is connected in series with a relay 1 and a relay 2 which are arranged in parallel;

[0007] The DC bus is connected in series with a braking unit, and a normally closed contact of a relay 2 is connected in series between the DC bus and the braking unit, and a braking resistor is connected in parallel with the braking unit;

[0008] The lifting motor circuit is connected in series with a normally closed contact of a relay.

[0009] Preferably, the frequency converter is also connected in series with a brake control circuit, the brake control circuit is connected in series with relay three, the main circuit is also connected in series with a lifting brake circuit, and the lifting brake circuit is connected in series with the normally open contact of relay three.

[0010] Preferably, the main circuit is also connected in series with a circuit breaker and a filter.

[0011] Preferably, the energy feedback unit is an active front end AFE, and the braking unit is a chopper.

[0012] Compared with the prior art, the beneficial effects of the utility model are:

[0013] 1. This system consists of an energy feedback unit and a frequency converter. During normal operation, the energy feedback unit provides DC power to the frequency converter, and the frequency converter acts as an inverter to achieve variable frequency speed control. The regenerated electric energy during the descent or deceleration process of the hoisting mechanism is returned to the energy feedback unit through the DC bus of the frequency converter, and is inverted into AC power with the same frequency and phase as the power grid and sent back to the power grid;

[0014] 2. When the energy feedback unit fails, it no longer has the rectification and energy feedback functions, the fault control circuit is disconnected, relay 1 and relay 2 are powered off, the corresponding normally closed contacts of relay 1 and relay 2 are closed, the hoisting motor circuit is connected to the AC power supply, the inverter is used for variable frequency speed control, and the brake unit is connected to the DC bus. When the hoisting mechanism is descending or decelerating, the regenerated electric energy of the hoisting mechanism can be consumed in the brake resistor through the brake unit, ensuring that the hoisting mechanism can safely and reliably achieve steady speed descent and deceleration;

[0015] In summary, this system can not only realize the functions of variable frequency speed regulation and energy feedback to the power grid, realize energy-saving control of variable frequency speed regulation, but also use the frequency converter and spare braking unit to maintain the continuous operation of the lifting mechanism when the feedback unit fails. It has a safety redundant control function to realize safe, reliable and efficient operation of the lifting mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the circuit principle of the utility model.

[0017] In the figure: 1 circuit breaker, 2 inverter, 3 filter, 4 energy feedback unit, 5 fault control circuit, 6 relay 1, 7 relay 2, 8 brake unit, 9 brake control circuit, 10 relay 3, 11 lifting motor circuit, 12 lifting brake circuit, 13 inverter, 14 DC bus. DETAILED DESCRIPTION

[0018] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "back", "left", "right", etc. indicating directions or positional relationships, they only correspond to the drawings of the present application for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific direction.

[0019] See also Figure 1 The utility model provides a technical solution: an energy-saving electric control system for a large-tonnage European crane, comprising a main circuit, an inverter 2, an energy feedback unit 4 and a frequency converter 13; the inverter 2 is connected in series in the main circuit, the inverter 2 is connected in series with the energy feedback unit 4, the energy feedback unit 4 is connected in series with the frequency converter 13 through a DC bus 14, the main circuit is connected in series with a lifting motor circuit 11, and the frequency converter 13 is connected in series with the lifting motor circuit 11;

[0020] The energy feedback unit 4 is connected in series with a fault control circuit 5, and the fault control circuit 5 is connected in series with a relay 1 6 and a relay 2 7 which are arranged in parallel;

[0021] The DC bus 14 is connected in series with the brake unit 8, and the normally closed contact of the relay 2 7 is connected in series between the DC bus 14 and the brake unit 8, and the brake unit 8 is connected in parallel with a brake resistor;

[0022] The lifting motor circuit 11 is connected in series with the normally closed contact of the relay 6;

[0023] It can be understood that when the energy feedback unit 4 is working normally, the energy feedback unit 4 provides a DC power supply to the frequency converter 13, and the frequency converter 13 acts as an inverter to realize the variable frequency speed control of the lifting motor. The regenerative electric energy generated during the descent or deceleration of the lifting mechanism is returned to the energy feedback unit 4 through the DC bus 14 of the frequency converter 13, and is inverted into an AC power with the same frequency and phase as the power grid and sent back to the power grid, realizing the functions of variable frequency speed regulation and energy feedback to the power grid, and realizing energy-saving control of variable frequency speed regulation; when the energy feedback unit 4 fails, the fault control circuit 5 connected in series with the energy feedback unit 4 When the lifting mechanism is disconnected, the relay 16 and the relay 27 are de-energized, and the corresponding normally closed contacts of the relay 16 and the normally closed contacts of the relay 27 are closed, the lifting motor circuit is connected to the AC power supply, and the inverter 13 frequency-controlled lifting motor, and at the same time the brake unit is connected to the DC bus 14, then when the lifting mechanism is descending or decelerating, the regenerated electric energy of the lifting mechanism can be converted into DC power through the inverter module of the inverter 13, and then consumed in the brake resistor, ensuring that the lifting mechanism can safely and reliably achieve steady-speed descent and deceleration, with a safety redundant control function, to achieve safe, reliable and efficient operation of the lifting mechanism

[0024] Specifically, the energy feedback unit 4 is an active front end AFE, and the braking unit 8 is a chopper;

[0025] Furthermore, the frequency converter 13 is also connected in series with a brake control circuit 9, the brake control circuit 9 is connected in series with a relay 3 10, the main circuit is also connected in series with a lifting brake circuit 12, and the lifting brake circuit 12 is connected in series with a normally open contact of the relay 3 10; the frequency converter 13 inputs a brake signal, the relay 3 10 of the brake control circuit 9 is energized, then the normally open contact of the relay 3 10 is closed, and the lifting brake circuit 12 is energized to perform a brake operation;

[0026] In addition, the main circuit is also connected in series with a circuit breaker 1 and a filter 3 .

[0027] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and it is intended to include all changes that fall within the meaning and scope of equivalent elements in the content of the present invention.

Claims

1. An energy-saving electric control system for a large-tonnage European crane, comprising a main circuit, an inverter (2), an energy feedback unit (4) and a frequency converter (13); characterized in that: The inverter (2) is connected in series in the main circuit, the inverter (2) is connected in series with the energy feedback unit (4), the energy feedback unit (4) is connected in series with the frequency converter (13) via the DC bus (14), the main circuit is connected in series with the lifting motor circuit (11), and the frequency converter (13) is connected in series with the lifting motor circuit (11); The energy feedback unit (4) is connected in series with a fault control circuit (5), and the fault control circuit (5) is connected in series with a relay 1 (6) and a relay 2 (7) which are arranged in parallel; The DC bus (14) is connected in series with a braking unit (8), and a normally closed contact of a second relay (7) is connected in series between the DC bus (14) and the braking unit (8), and a braking resistor is connected in parallel with the braking unit (8); The lifting motor circuit (11) is connected in series with the normally closed contact of relay 1 (6).

2. According to claim 1, an energy-saving electric control system for a large-tonnage European crane is characterized in that: The frequency converter (13) is also connected in series with a brake control circuit (9), the brake control circuit (9) is connected in series with a relay three (10), the main circuit is also connected in series with a lifting brake circuit (12), and the lifting brake circuit (12) is connected in series with a normally open contact of the relay three (10).

3. The energy-saving electric control system for a large-tonnage European crane according to claim 1 is characterized in that: The main circuit is also connected in series with a circuit breaker (1) and a filter (3).

4. The energy-saving electric control system for a large-tonnage European crane according to claim 1 is characterized in that: The energy feedback unit (4) is an active front end AFE, and the braking unit (8) is a chopper.

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