Tower crane control room frequency conversion control system with energy feedback function

Abstract

The utility model discloses a tower crane control room frequency conversion control system with an energy feedback function, which comprises an external power grid (1), a frequency converter (2), a lifting motor (3), a variable amplitude motor (4) and a rotary motor (5), and the frequency converter (2) is electrically connected with an energy feedback unit (6), an energy storage battery (7), an inverter circuit device (8) and a PLC (Programmable Logic Controller) (9); the PLC (9) is connected with a second relay (10), a third relay (11) and a fourth relay (12); a normally open contact of the second relay (10) is arranged between the lifting motor (3) and the frequency converter (2); a normally open contact of the third relay (11) is arranged between the variable amplitude motor (4) and the frequency converter (2); and a normally open contact of the fourth relay (12) is arranged between the rotary motor (5) and the frequency converter (2). The utility model not only can realize the purpose of energy conservation, but also has the advantages of long service life, simple structure and high working stability.

Description

Technical Field

[0001] The utility model relates to a tower crane cab control system, in particular to a variable frequency control system for a tower crane cab with an energy feedback function. Background Art

[0002] A tower crane drives a motor to rotate by using a frequency converter, thereby driving a running mechanism to act. The motor consumes electric energy during forward rotation, while the motor is in a power generation state and generates electric energy during braking and reverse rotation. If the generated electric energy is directly transmitted into the frequency converter, it will cause damage to the output module of the frequency converter. Therefore, in the existing tower crane control system, the electric energy generated by the motor during braking and reverse rotation is mainly released as heat through a resistor; such a method not only wastes energy but also causes environmental pollution. Therefore, there is a problem of energy waste in the existing tower crane variable frequency control system when dealing with the electric energy generated by the motor during braking and reverse rotation. Content of the Utility Model

[0003] The purpose of the utility model is to provide a variable frequency control system for a tower crane cab with an energy feedback function, which has the advantage of energy saving.

[0004] The technical solution of the utility model: A variable frequency control system for a tower crane cab with an energy feedback function includes an external power grid, a frequency converter electrically connected to the external power grid, a hoisting motor, a luffing motor, and a slewing motor for driving the tower crane to operate. An energy feedback unit is electrically connected to the frequency converter, and a storage battery is electrically connected to the energy feedback unit; an inverter and a PLC controller are electrically connected to the storage battery; a second relay, a third relay, and a fourth relay are electrically connected to the PLC controller. The normally open contact of the second relay is arranged between the hoisting motor and the frequency converter; the normally open contact of the third relay is arranged between the luffing motor and the frequency converter; the normally open contact of the fourth relay is arranged between the slewing motor and the frequency converter; the storage battery can store the redundant electric energy during the braking process of the motor; moreover, one end of the storage battery is connected to the PLC controller, and one end is connected between the external power grid and the frequency converter through an inverter, so that the electric energy stored in the storage battery can not only be used as the electric energy for the PLC controller to work, but also be re-transmitted to the external power grid for power supply at an appropriate time, so that the electric energy of the entire control system can be maximally utilized, making the entire system more energy-saving; the hoisting motor, the luffing motor, and the slewing motor are electrically connected to the output end of the frequency converter. With the normally open contacts on the second relay, the third relay, and the fourth relay, the PLC controller can quickly and simply control the start and stop of the corresponding hoisting motor, luffing motor, and slewing motor, and the overall structure is simpler.

[0005] In the above-mentioned frequency conversion control system for the tower crane cab with energy feedback function, a first relay is connected in parallel between the frequency converter and the external power grid, and the normally closed contact of the first relay is electrically connected between the inverter and the external power grid; by setting the normally closed contact of the first relay between the inverter and the external power grid, when the external power grid is supplying power normally, the inverter and the external frequency converter are in a disconnected state, that is, the electric energy in the energy storage battery is only used for the operation of the PLC controller; and when the external power grid suddenly loses power, the circuit between the inverter and the frequency converter is connected, and the inverter can be used to deliver the electric energy in the energy storage battery to the frequency converter for emergency power supply, so as to avoid the phenomenon that each working mechanism of the tower crane suffers from inertial impact due to sudden power failure, reduce the damage of each working mechanism of the tower crane, and extend the service life.

[0006] In the above-mentioned frequency conversion control system for the tower crane cab with energy feedback function, the PLC controller is electrically connected to the external power grid; a fifth relay is electrically connected between the energy storage battery and the PLC controller, and the normally closed contact of the fifth relay is set between the PLC controller and the external power grid; by setting a fifth relay between the PLC controller and the energy storage battery and setting the normally closed contact of the fifth relay between the PLC controller and the external power grid, it can ensure that the external power grid can supply power to the PLC controller when the electric energy in the energy storage battery is insufficient, so as to ensure the stable operation of the PLC controller and the stability of the work.

[0007] In the above-mentioned frequency conversion control system for the tower crane cab with energy feedback function, the energy storage battery is a DC energy storage battery.

[0008] In the above-mentioned frequency conversion control system for the tower crane cab with energy feedback function, the frequency converter includes a housing, and a plurality of evenly distributed heat dissipation fins are provided on the housing; the setting of the heat dissipation fins improves the heat dissipation effect of the entire frequency converter and extends the service life.

[0009] In the above-mentioned frequency conversion control system for the tower crane cab with energy feedback function, an electric fan is provided inside the housing.

[0010] Compared with the prior art, the utility model improves the existing tower crane driving control system. An energy storage battery is electrically connected to the energy feedback unit, and the energy storage battery can store the redundant electric energy during the electric braking process of the motor. One end of the energy storage battery is connected to a PLC controller, and the other end is connected between the external power grid and the frequency converter through an inverter circuit, so that the electric energy stored in the energy storage battery can not only be used as the electric energy for the operation of the PLC controller, but also be re-transmitted to the external power grid for power supply at an appropriate time, maximizing the utilization of the electric energy of the entire control system and making the entire system more energy-efficient. At the same time, a hoisting motor, a luffing motor, and a slewing motor are electrically connected to the output end of the frequency converter. With the normally open contacts on the second relay, the third relay, and the fourth relay, the PLC controller can quickly and simply control the start and stop of the corresponding hoisting motor, luffing motor, and slewing motor, and can realize that one frequency converter controls the hoisting motor, luffing motor, and slewing motor at the same time. Compared with the previous method of using one frequency converter to control one motor, the overall structure is simpler. In addition, the utility model also sets a first relay between the frequency converter and the external power grid, and sets the normally closed contact of the first relay between the inverter circuit and the external power grid, so that when the external power grid is normally powered, the inverter circuit and the external frequency converter are in a disconnected state, that is, the electric energy in the energy storage battery is only used for the operation of the PLC controller. When the external power grid suddenly loses power, the circuit between the inverter circuit and the frequency converter is connected, and the inverter circuit can transmit the electric energy in the energy storage battery to the frequency converter for emergency power supply, thus avoiding the phenomenon that the sudden power failure causes inertial impact on each working mechanism of the tower crane, reducing the damage of each working mechanism of the tower crane, and extending the service life. By setting a fifth relay between the PLC controller and the energy storage battery, and setting the normally closed contact of the fifth relay between the PLC controller and the external power grid, it can ensure that the external power grid can supply power to the PLC controller when the electric energy in the energy storage battery is insufficient, so as to ensure the stable operation of the PLC controller and the stability of the work. By setting a plurality of heat dissipation fins on the outer shell of the frequency converter and installing an electric fan inside the outer shell, the heat dissipation fins and the electric fan can cooperate to dissipate heat from the inside and outside of the frequency converter, avoiding the damage of the frequency converter due to overheating and extending the service life. Therefore, the utility model can not only achieve the purpose of energy conservation, but also has the advantages of long service life, simple structure, and high working stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic structural diagram of the utility model;

[0012] Figure 2 is a schematic structural diagram of the frequency converter.

[0013] The labels in the attached drawings are as follows: 1-external power grid, 2-frequency converter, 3-lifting motor, 4-luffing motor, 5-slewing motor, 6-energy feedback unit, 7-energy storage battery, 8-inverter circuit breaker, 9-PLC controller, 10-second relay, 11-third relay, 12-fourth relay, 13-first relay, 14-fifth relay, 15-housing, 16-radiating fins. Detailed implementation mode

[0014] The present utility model will be further described below in conjunction with the attached drawings and embodiments, but it shall not be used as the basis for limiting the present utility model.

[0015] Embodiment. The frequency conversion control system of the tower crane cab with energy feedback function is configured as shown in Figure 1 and 2 and includes an external power grid 1, a frequency converter 2 electrically connected to the external power grid 1, a lifting motor 3, a luffing motor 4, and a slewing motor 5 for driving the tower crane to operate. An energy feedback unit 6 is electrically connected to the frequency converter 2, and an energy storage battery 7 is electrically connected to the energy feedback unit 6; an inverter circuit breaker 8 and a PLC controller 9 are electrically connected to the energy storage battery 7; a second relay 10, a third relay 11, and a fourth relay 12 are electrically connected to the PLC controller 9. The normally open contact of the second relay 10 is arranged between the lifting motor 3 and the frequency converter 2; the normally open contact of the third relay 11 is arranged between the luffing motor 4 and the frequency converter 2; the normally open contact of the fourth relay 12 is arranged between the slewing motor 5 and the frequency converter 2.

[0016] A first relay 13 is connected in parallel between the frequency converter 2 and the external power grid 1, and the normally closed contact of the first relay 13 is electrically connected between the inverter circuit breaker 8 and the external power grid 1; the PLC controller 9 is electrically connected to the external power grid 1; a fifth relay 14 is electrically connected between the energy storage battery 7 and the PLC controller 9, and the normally closed contact of the fifth relay 14 is arranged between the PLC controller 9 and the external power grid 1; the energy storage battery 7 is a DC energy storage battery; the frequency converter 2 includes a housing 15, and a plurality of evenly distributed radiating fins 16 are arranged on the housing 15; an electric fan is arranged inside the housing 15.

[0017] Working principle: When the external power grid 1 is supplying power normally, a part of the external electric energy is transmitted to the PLC controller 9 for the initial working current of the PLC controller 9; another part is transmitted to the hoisting motor 3, the luffing motor 4 or the slewing motor 5 through the frequency converter 2 for the operation of the hoisting motor 3, the luffing motor 4 or the slewing motor 5; when the hoisting motor 3, the luffing motor 4 or the slewing motor 5 brakes or slews, a certain amount of electric energy will be generated, and this part of the electric energy will be transmitted to the energy feedback unit 6 through the frequency converter 2, and the energy feedback unit 6 will transmit this part of the electric energy to the energy storage battery 7 for electric energy storage; when there is electric energy in the energy storage battery 7, it will be used to supply power to the PLC controller 9 for operation, and at this time the fifth relay 14 will also be powered on and started, so that the connection between the PLC controller 9 and the external power grid 1 is disconnected, and the energy storage battery 7 becomes the main power supply for the operation of the PLC controller 9; at the same time, when it is necessary to control the start and stop of the corresponding hoisting motor 3, luffing motor 4 or slewing motor 5, only need to control the second relay 10, the third relay 11 or the fourth relay 12 to start through the PLC controller 9, so that the normally open contacts corresponding to the second relay 10, the third relay 11 or the fourth relay 12 are closed, and then the corresponding hoisting motor 3, luffing motor 4 or slewing motor 5 is connected to the frequency converter 2, so that the hoisting motor 3, luffing motor 4 or slewing motor 5 starts; when the external power grid 1 has a power outage, the first relay 13 will close, and at this time the normally closed contact of the first relay 13 will change from the open state to the closed state, so that the inverter 8 and the frequency converter 2 change from the disconnected state to the connected state, so that the energy storage battery 7 can operate the frequency converter 2 for a certain period of time, thus avoiding problems such as collisions caused by inertia when suddenly powering off, and reducing the phenomenon of damage to the hoisting motor 3, luffing motor 4 or slewing motor 5, and extending the service life.

Claims

1. The frequency conversion control system for the tower crane driver's cab with energy feedback function, comprising an external power grid (1), an inverter (2) electrically connected to the external power grid (1), a hoisting motor (3), a luffing motor (4) and a slewing motor (5) for driving the tower crane to operate, characterized in that: An energy feedback unit (6) is electrically connected to the frequency converter (2), and a storage battery (7) is electrically connected to the energy feedback unit (6); an inverter (8) and a PLC controller (9) are electrically connected to the storage battery (7); a second relay (10), a third relay (11) and a fourth relay (12) are electrically connected to the PLC controller (9), and normally open contacts of the second relay (10) are arranged between the hoisting motor (3) and the frequency converter (2); normally open contacts of the third relay (11) are arranged between the luffing motor (4) and the frequency converter (2); normally open contacts of the fourth relay (12) are arranged between the slewing motor (5) and the frequency converter (2).

2. The frequency conversion control system for the tower crane cab with energy feedback function according to claim 1, wherein: A first relay (13) is connected in parallel between the frequency converter (2) and the external power grid (1), and normally closed contacts of the first relay (13) are electrically connected between the inverter (8) and the external power grid (1).

3. The frequency conversion control system for the tower crane cab with energy feedback function according to claim 1, characterized in that: The PLC controller (9) is electrically connected to the external power grid (1); a fifth relay (14) is electrically connected between the storage battery (7) and the PLC controller (9), and normally closed contacts of the fifth relay (14) are arranged between the PLC controller (9) and the external power grid (1).

4. The frequency conversion control system for the tower crane operator's cab with energy feedback function according to claim 1, characterized in that: The storage battery (7) is a DC storage battery.

5. The frequency conversion control system for the tower crane cab with energy feedback function according to any one of claims 1 to 4, characterized in that: The frequency converter (2) includes a housing (15), and a plurality of evenly distributed heat dissipation fins (16) are arranged on the housing (15).

6. The frequency conversion control system for the tower crane cab with energy feedback function according to claim 5, characterized in that: An electric fan is arranged inside the housing (15).

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