Control circuit for energy-saving contactor

Abstract

The utility model discloses a control circuit for an energy-saving contactor. The power supply input end is provided with an L-phase input end and an N-phase input end and is used for inputting direct current or alternating current; the contactor coil is used for attracting and maintaining a contactor loop; the pull-in loop is respectively connected with the power supply input end and the contactor coil; the maintaining loop comprises a switching power supply used for converting the voltage input by the power supply input end, and the output end of the switching power supply is connected with the contactor coil; and a coil of the relay is connected in series in an output branch of the maintaining loop, a normally closed end of the relay is connected in series in an input branch of the pull-in loop, and the relay is used for cutting off the pull-in loop after the contactor is pulled in. By designing the independent pull-in loop and the maintenance loop, the on-off of the pull-in loop is controlled through the relay, during normal starting, power supply pull-in is performed on a contactor coil through the pull-in loop, then maintenance is performed through the maintenance loop, voltage conversion is performed through the switching power supply, low-voltage maintenance is realized, and the energy-saving effect is realized.

Description

Technical Field

[0001] This utility model relates to AC contactors, and more specifically to a control circuit for an energy-saving contactor. Background Technology

[0002] As is well known, in electrical engineering, a contactor is an automated switch used to connect or disconnect AC or DC main circuits or high-capacity control circuits of loads. Its main control object is the electric motor, but it can also be used for other electrical loads such as electric heaters, welding machines, and lighting equipment. Contactors can not only connect and disconnect circuits, but also have low-voltage release protection. Furthermore, contactors have a large control capacity and are suitable for frequent operation and remote control, making them one of the important components in automatic control systems.

[0003] As energy-saving requirements for contactors gradually increase, the new national standard GB21518-2008 specifies the energy efficiency levels, energy efficiency limits, energy-saving evaluation values, and test methods for AC contactors. It divides the energy efficiency levels of contactors into three levels: Level 1, Level 2, and Level 3, measured by holding power VA. A VA level of 3 indicates a contactor meeting the entry-level standard, while Levels 2 and 1 are energy-saving products. This has played a positive role in promoting the research and application of energy-saving and noise-free technologies for AC contactors.

[0004] To improve energy efficiency, most existing systems use dual-coil control. For example, Chinese patent CN203895364U discloses a dual-coil energy-saving contactor power switch, which uses a starting winding and a holding winding to perform high-current engagement and low-current maintenance of engagement, thereby reducing energy consumption and ensuring that the contactor's energy efficiency rating meets national standards. However, this method requires adding coils to the contactor. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a control circuit for an energy-saving contactor.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A control circuit for an energy-saving contactor, comprising:

[0008] A power input terminal with L-phase and N-phase inputs for DC or AC power input;

[0009] Contactor coil TQ1 is used for contactor circuit engagement and maintenance.

[0010] The engagement circuit is connected to the power input terminal and the contactor coil, respectively.

[0011] The sustaining circuit includes a switching power supply for converting the voltage input to the power supply input terminal, the output terminal of which is connected to a contactor coil;

[0012] Relay JK1 has its coil connected in series in one output branch of the holding circuit, and its normally closed terminal connected in series in the input branch of the energizing circuit, used to cut off the energizing circuit after the contactor is energized.

[0013] A varistor RY1 is connected in parallel between the L-phase and N-phase input terminals.

[0014] The normally closed output terminal of the relay JK1 is divided into two paths. One path is directly connected to one end of the contactor coil TQ1, and the other end is connected to one end of the contactor coil TQ1 in series through diodes D4 and D6. The connection point of diodes D4 and D6 is grounded through an electrolytic capacitor.

[0015] One end of the coil of the relay JK1 is connected to the contactor coil TQ1 via diode D3.

[0016] The switching power supply includes an input circuit, a power chip U1, and an output circuit.

[0017] The output circuit of the switching power supply is also equipped with an indicator circuit.

[0018] The input circuit includes a diode D5 connected in series between the L-phase input terminal and the power chip U1, and an electrolytic capacitor for grounding.

[0019] The power chip U1 is an XD308H.

[0020] The beneficial effects of this utility model are as follows: By designing independent pull-in circuit and holding circuit, and controlling the on / off state of the pull-in circuit through a relay, during normal startup, the contactor coil is first powered through the pull-in circuit and pulled in. Then, because the holding circuit powers the relay coil, the normally closed terminal of the relay is opened, cutting off the pull-in circuit. The holding circuit then provides power to maintain the state. At the same time, the voltage is converted through a switching power supply to achieve low voltage maintenance and achieve energy saving. Attached Figure Description

[0021] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0024] like Figure 1 As shown, this utility model discloses a control circuit for an energy-saving contactor, which can be applied to the contactor without replacing the contactor coil, and directly utilizes the original contactor structure.

[0025] The control circuit includes a power input terminal and a contactor coil, a pull-in circuit and a holding circuit connected in parallel between the power input terminal and the contactor coil, the contactor coil, and a relay JK1 that controls the pull-in circuit. The holding circuit is designed based on a switching power supply. During operation, the pull-in circuit will conduct first, so a large current can be used to power the contactor coil to close the contactor. Then, due to the conduction of the holding circuit, the coil of relay JK1 is energized, thus opening the pull-in circuit. The output voltage of the switching power supply is then used to maintain the pull-in state, achieving an energy-saving effect.

[0026] The power input terminal has L-phase and N-phase input terminals for DC or AC power input.

[0027] Contactor coil TQ1 is used for contactor circuit engagement and maintenance. It uses the contactor's own coil and requires no additional modification to the coil.

[0028] The engagement circuit is connected to both the power input terminal and the contactor coil. The engagement circuit directly connects the power input terminal and the contactor coil, thereby achieving a rapid engagement effect.

[0029] The sustaining circuit includes a switching power supply for converting the voltage input at the power input terminal. The output terminal of the switching power supply is connected to the contactor coil. The sustaining circuit uses the converted voltage from the switching power supply to power the contactor coil, maintain the engaged state, and reduce energy consumption.

[0030] Relay JK1, with its coil connected in series in one output branch of the holding circuit and its normally closed terminal connected in series in the input branch of the pull-in circuit, is used to disconnect the pull-in circuit after the contactor is engaged. Relay JK1 links the pull-in circuit and the holding circuit, using the continuity of the holding circuit to disconnect the pull-in circuit. Simultaneously, when the holding circuit fails, it can also switch back to the pull-in circuit via the relay, ensuring the normal operation of the entire power supply circuit.

[0031] A varistor RY1 is connected in parallel between the L-phase and N-phase input terminals, and the varistor RY1 serves as a protection device.

[0032] The normally closed output terminal of the relay JK1 is divided into two paths. One path is directly connected to one end of the contactor coil TQ1, and the other end is connected to one end of the contactor coil TQ1 in series through diodes D4 and D6. The connection point of diodes D4 and D6 is grounded through electrolytic capacitor E1.

[0033] Through the synergistic effect of the dual diodes and the electrolytic capacitor E1, when the energizing circuit is cut off, the electrolytic capacitor E1 discharges to maintain the energized state and prevent the phenomenon of fluctuation caused by voltage changes when the energizing circuit is cut off.

[0034] One end of the coil of the relay JK1 is connected to the contactor coil TQ1 through diode D3, which protects the coil.

[0035] The switching power supply includes an input circuit, a power chip U1, and an output circuit. The power chip U1 is an XD308H. The XD308H is a non-isolated high-dropout AC-DC converter power chip with an ultra-wide input range of 18-600V. It can adapt to an ultra-wide input voltage range of 12-380VAC (with external rectification and filtering). The maximum continuous output current can reach 500mA (peak 800mA). It has no audible noise, low heat generation, and integrates comprehensive protection functions (short circuit protection, overload protection, output overvoltage protection, output undervoltage protection, overheat protection, etc.).

[0036] The output circuit of the switching power supply is also equipped with an indicator circuit, which uses a light-emitting diode LED1 and a resistor R4 to indicate the operation of the switching power supply. When the switching power supply fails, the status of the maintenance circuit can be directly and intuitively understood, and the power supply can be replaced during production breaks.

[0037] The input circuit includes a diode D5 connected in series between the L-phase input terminal and the power chip U1, and an electrolytic capacitor for grounding. The diode D5 provides rectification, and the electrolytic capacitor provides filtering.

[0038] Its output circuit references the peripheral circuit of the XD308H; see details below. Figure 1 .

[0039] The embodiments should not be regarded as limitations on the present invention, but any improvements made based on the spirit of the present invention should be within the protection scope of the present invention.

Claims

1. A control circuit for an energy-saving contactor, characterized in that: It includes: A power input terminal with L-phase and N-phase inputs for DC or AC power input; Contactor coil TQ1 is used for contactor circuit engagement and maintenance. The engagement circuit is connected to the power input terminal and the contactor coil, respectively. The sustaining circuit includes a switching power supply for converting the voltage input to the power supply input terminal, the output terminal of which is connected to a contactor coil; Relay JK1 has its coil connected in series in one output branch of the holding circuit, and its normally closed terminal connected in series in the input branch of the energizing circuit, used to cut off the energizing circuit after the contactor is energized.

2. The control circuit for an energy-saving contactor according to claim 1, characterized in that: A varistor RY1 is connected in parallel between the L-phase and N-phase input terminals.

3. The control circuit for an energy-saving contactor according to claim 1, characterized in that: The normally closed output terminal of the relay JK1 is divided into two paths. One path is directly connected to one end of the contactor coil TQ1, and the other end is connected to one end of the contactor coil TQ1 in series through diodes D4 and D6. The connection point of diodes D4 and D6 is grounded through an electrolytic capacitor.

4. A control circuit for an energy-saving contactor according to claim 1, characterized in that: One end of the coil of the relay JK1 is connected to the contactor coil TQ1 via diode D3.

5. A control circuit for an energy-saving contactor according to claim 1, characterized in that: The switching power supply includes an input circuit, a power chip U1, and an output circuit.

6. A control circuit for an energy-saving contactor according to claim 1 or 5, characterized in that: The output circuit of the switching power supply is also equipped with an indicator circuit.

7. A control circuit for an energy-saving contactor according to claim 5, characterized in that: The input circuit includes a diode D5 connected in series between the L-phase input terminal and the power chip U1, and an electrolytic capacitor for grounding.

8. A control circuit for an energy-saving contactor according to claim 5, characterized in that: The power chip U1 is an XD308H.

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