A capacitor device

Abstract

The utility model relates to a kind of capacitor devices, it is externally placed in the control box of frequency conversion system, the capacitor device includes installation box, and capacitor component, rectifier bridge, charging resistance and DC contactor installed in installation box, the incoming power end of the rectifier bridge is electrically connected three-phase power supply, the output positive pole of the rectifier bridge is electrically connected charging resistance one end and DC contactor one main contact point, the other end of the charging resistance is used as positive output end for electrically connected input positive pole of frequency conversion system, and the positive output end is also electrically connected DC contactor another main contact point and the positive pole of capacitor component;The output negative pole of the rectifier bridge is used as negative output end for electrically connected input negative pole of frequency conversion system, and the negative output end is electrically connected the negative pole of capacitor component;The control coil of the DC contactor is electrically connected frequency conversion system.The utility model can improve the power grid adaptability of frequency conversion system, improve frequency converter capacity, and be easily reformed, and cost is lower.

Description

Technical Field

[0001] This utility model relates to the field of frequency converter control system technology, and in particular to a capacitor device. Background Technology

[0002] In variable frequency drive (VFD) systems, capacitors are one of the core components, serving multiple functions and being crucial for system stability. Generally, the most important roles of capacitors in VFD systems are energy storage and filtering. Due to factors such as power grid upgrades, early VFD systems had poor grid adaptability, mainly manifested in insufficient capacity (energy storage) and poor ability to cope with grid fluctuations. Furthermore, due to cost considerations, the layout of VFD system equipment boxes is often quite compact. Therefore, if expansion or other upgrades are needed, it often requires replacing the equipment box and rearranging the electrical components, which is relatively time-consuming, labor-intensive, and costly. Therefore, providing a more convenient and economical upgrade solution for older VFD systems is indeed necessary. Utility Model Content

[0003] The purpose of this invention is to provide a capacitor device that can improve the grid adaptability of the frequency conversion system, increase the capacity of the frequency converter, and is easy to modify and has a low cost.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A capacitor device is externally mounted in the control box of a frequency converter system. The capacitor device includes a mounting box, and a capacitor assembly, a rectifier bridge, a charging resistor, and a DC contactor mounted in the mounting box. The input terminal of the rectifier bridge is electrically connected to a three-phase power supply. The positive output terminal of the rectifier bridge is electrically connected to one end of the charging resistor and one of the main contacts of the DC contactor. The other end of the charging resistor serves as a positive output terminal for electrically connecting to the positive input terminal of the frequency converter system, and the positive output terminal is also electrically connected to another main contact of the DC contactor and the positive terminal of the capacitor assembly. The negative output terminal of the rectifier bridge serves as a negative output terminal for electrically connecting to the negative input terminal of the frequency converter system, and the negative output terminal is electrically connected to the negative terminal of the capacitor assembly. The control coil of the DC contactor is electrically connected to the frequency converter system.

[0005] After the above settings, by setting a charging resistor, excessive charging current (in this case, charging refers to the instant the circuit is turned on) can be prevented, avoiding large current surges to the frequency converter system. After the frequency converter is powered on, 24V power can be output to the control coil of the DC contactor, thereby controlling the main contacts of the DC contactor to conduct, which in turn short-circuits the charging resistor. Simultaneously, the capacitors inside the frequency converter system are connected in parallel with the capacitor components in the capacitor bank, improving the insufficient capacity of the frequency converter and enhancing its ability to cope with grid fluctuations, thus strengthening the grid adaptability of the frequency converter system. By placing the capacitor bank externally in the control box of the frequency converter system, the capacitor bank does not occupy the internal space of the control box, which is very beneficial for upgrading and retrofitting old systems, and also facilitates maintenance and repair.

[0006] Preferably, the capacitor device further includes a connector, which is disposed on the wall of the mounting box. The input terminal of the rectifier bridge is electrically connected to the three-phase power supply via the connector, the positive output terminal is electrically connected to the positive input terminal of the frequency converter system via the connector, the negative output terminal is electrically connected to the negative input terminal of the frequency converter system via the connector, and the control coil of the DC contactor is electrically connected to the frequency converter system via the connector. By providing the connector, convenient electrical connections inside and outside the mounting box can be ensured.

[0007] Preferably, the connector is a through-wall terminal block.

[0008] Preferably, the capacitor assembly includes at least one capacitor, and all the capacitors are connected in parallel.

[0009] Preferably, the capacitor assembly further includes a connecting circuit board, on which the capacitors are fixed and connected in parallel. The positive and negative terminals of the capacitor assembly are located on the connecting circuit board. By providing the connecting circuit board, the capacitor assembly can be formed as a single unit, facilitating assembly.

[0010] Preferably, the rectifier bridge, charging resistor, and DC contactor are all located on the same side of the capacitor assembly, which is positioned close to three adjacent walls of the control box, and at least these three walls are made of thermally conductive material. This arrangement makes it less likely for the heat generated during the charging and discharging of the capacitor assembly to affect the operation of other electrical components, and also facilitates heat dissipation.

[0011] Preferably, the mounting box has a closed structure. This design prevents dust, debris, insects, and other contaminants from entering the mounting box and causing danger.

[0012] Preferably, the bottom of the mounting box is made of insulating material, and the capacitor assembly, rectifier bridge, charging resistor, and DC contactor are all mounted on the bottom of the mounting box; alternatively, the bottom of the mounting box is provided with an insulating mounting plate, and the capacitor assembly, rectifier bridge, charging resistor, and DC contactor are all mounted on the insulating mounting plate. This arrangement improves electrical safety.

[0013] This utility model has the following beneficial effects: This invention, by incorporating a charging resistor, prevents excessive charging current (in this case, charging refers to the instant the circuit is turned on), thus avoiding high current surges into the frequency converter system. After the frequency converter is powered on, it outputs 24V to the control coil of the DC contactor, controlling the main contacts of the DC contactor to conduct, thereby short-circuiting the charging resistor. Simultaneously, it connects the capacitors inside the frequency converter system in parallel with the capacitor bank, improving the inverter's insufficient capacity and enhancing its ability to cope with grid fluctuations, thereby increasing the frequency converter system's grid adaptability. By externally placing the capacitor bank within the frequency converter system's control box, it does not occupy internal space, facilitating upgrades and maintenance of older systems. Furthermore, it reduces upgrade costs and offers greater flexibility. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the present invention.

[0015] Figure 2 This is a schematic diagram of the concealed part of this utility model after the box is installed.

[0016] Figure 3 This is a schematic diagram of a capacitor assembly.

[0017] Figure 4 This is the circuit schematic diagram of this utility model.

[0018] Explanation of symbols for main components: Installation box 10, box bottom 11; Connector 20; 30 rectifier bridge; Charging resistance 40; DC contactor 50; Capacitor 61 is connected to circuit board 62. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] like Figure 1-4 As shown, this utility model discloses a capacitor 61 device, which is externally placed in the control box of the frequency converter system. In this way, when the frequency converter system is upgraded, the external capacitor 61 device will not occupy the internal space of the old frequency converter system control box, thus providing more space for modification. The capacitor 61 device is independent of the old control box, and the heat dissipation is also better.

[0021] The capacitor 61 device includes a mounting box 10, a capacitor assembly, a rectifier bridge 30, a charging resistor 40, a DC contactor 50, and a connector 20. The bottom 11 of the mounting box 10 is made of insulating material, and the capacitor assembly, rectifier bridge 30, charging resistor 40, and DC contactor 50 are all mounted on the bottom 11 of the mounting box 10. Alternatively, an insulating mounting plate is provided on the bottom 11 of the mounting box 10, and the capacitor assembly, rectifier bridge 30, charging resistor 40, and DC contactor 50 are all mounted on the insulating mounting plate. In addition, the mounting box 10 is designed as a closed structure to prevent dust, debris, insects, etc. from entering the mounting box 10 and causing danger.

[0022] Connector 20 is installed on the wall of the mounting box 10 to facilitate the entry and exit of power into and out of the mounting box 10. Specifically, in this case, the connector 20 is a through-wall terminal block. There are seven connectors 20, three for introducing three-phase power, two for leading out DC power, and two for introducing control power (controlling the control coil of the DC contactor 50).

[0023] The DC contactor 50 has a pair of main contacts, which are normally open contacts.

[0024] The input terminal of the rectifier bridge 30 is electrically connected to an external three-phase power supply (R / S / T) via a corresponding connector 20, thereby rectifying the three-phase AC power into DC power. The positive output terminal of the rectifier bridge 30 is electrically connected via a wire or copper busbar to one end of a charging resistor 40 and one of the main contacts of a DC contactor 50. The other end of the charging resistor 40 serves as the positive output terminal, electrically connected to the positive input terminal IN+ of the frequency converter system (connected via a wire or copper busbar to the corresponding connector 20, which then electrically connects to the positive input terminal of the frequency converter system). The positive output terminal is also electrically connected to another main contact of the DC contactor 50 and the positive terminal of the capacitor assembly. The negative output terminal of the rectifier bridge 30 serves as the negative output terminal, electrically connected to the negative input terminal IN- of the frequency converter system (connected via a wire or copper busbar to the corresponding connector 20, which then electrically connects to the negative input terminal of the frequency converter system). The negative output terminal is also electrically connected to the negative terminal of the capacitor assembly. The control coil of the DC contactor 50 is electrically connected to the frequency converter of the frequency converter system via the corresponding connector 20.

[0025] The capacitor assembly includes a connecting circuit board 62 and at least one capacitor 61. All capacitors 61 are fixed on the connecting circuit board 62 and are connected in parallel through the connecting circuit board 62. The connecting circuit board 62 is provided with terminals or contacts as the positive and negative terminals of the capacitor assembly.

[0026] Because the capacitor assembly generates a lot of heat during charging and discharging, the electrical components inside the mounting box 10 are arranged as follows: the rectifier bridge 30, charging resistor 40, and DC contactor 50 are all placed on the same side of the capacitor assembly, and the capacitor assembly is placed close to the side, so that the capacitor assembly is close to the three adjacent boxes of the control box, and at least these three boxes are made of thermally conductive material. In this way, the heat generated by the charging and discharging of the capacitor assembly is less likely to affect the operation of other electrical components, and it is also conducive to heat dissipation.

[0027] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A capacitor device, characterized in that: The control box of the external frequency converter system includes a capacitor device comprising a mounting box, a capacitor assembly, a rectifier bridge, a charging resistor, and a DC contactor installed in the mounting box. The input terminal of the rectifier bridge is electrically connected to a three-phase power supply. The positive output terminal of the rectifier bridge is electrically connected to one end of the charging resistor and one of the main contacts of the DC contactor. The other end of the charging resistor serves as the positive output terminal for electrically connecting to the positive input terminal of the frequency converter system, and the positive output terminal is also electrically connected to the other main contact of the DC contactor and the positive terminal of the capacitor assembly. The negative output terminal of the rectifier bridge serves as the negative output terminal for electrically connecting to the negative input terminal of the frequency converter system, and the negative output terminal is electrically connected to the negative terminal of the capacitor assembly. The control coil of the DC contactor is electrically connected to the frequency converter system.

2. The capacitor device according to claim 1, characterized in that: The capacitor device also includes a connector, which is mounted on the wall of the mounting box. The input terminal of the rectifier bridge is electrically connected to the three-phase power supply through the connector. The positive output terminal is electrically connected to the positive input terminal of the frequency converter system through the connector. The negative output terminal is electrically connected to the negative input terminal of the frequency converter system through the connector. The control coil of the DC contactor is electrically connected to the frequency converter system through the connector.

3. The capacitor device according to claim 2, characterized in that: The connector is a through-wall terminal block.

4. The capacitor device according to claim 1, characterized in that: The capacitor assembly includes at least one capacitor, and all the capacitors are connected in parallel.

5. The capacitor device according to claim 4, characterized in that: The capacitor assembly also includes a connecting circuit board, the capacitors are fixed on the connecting circuit board, and the capacitors are connected in parallel through the connecting circuit board. The positive and negative terminals of the capacitor assembly are located on the connecting circuit board.

6. The capacitor device according to claim 1, characterized in that: The rectifier bridge, charging resistor, and DC contactor are all located on the same side of the capacitor assembly, which is located close to three adjacent walls of the control box, and at least these three walls are made of thermally conductive material.

7. The capacitor device according to claim 1, characterized in that: The installation box has a closed structure.

8. The capacitor device according to claim 1, characterized in that: The bottom of the mounting box is made of insulating material, and the capacitor assembly, rectifier bridge, charging resistor and DC contactor are all mounted on the bottom of the mounting box; or, the bottom of the mounting box is provided with an insulating mounting plate, and the capacitor assembly, rectifier bridge, charging resistor and DC contactor are all mounted on the insulating mounting plate.

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