AC contactor drive circuit and contactor

Abstract

The utility model provides an AC contactor driving circuit and a contactor, and the AC contactor driving circuit comprises an isolation transformer, a rectification circuit and an auxiliary power supply, provides a stable driving power supply for an AC contactor through the isolation transformer and the rectification circuit, and guarantees the working reliability of the contactor. Dual-power-supply switching is achieved through the auxiliary power supply and the auxiliary contacts of the contactors, extra control of the controller is not needed, the structure is simple, the main contacts and the auxiliary contacts of the contactors are mechanically connected, and the switching reliability is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of contactors, in particular to an AC contactor driving circuit and a contactor. BACKGROUND

[0002] A contactor is an electrical component used to control an electrical circuit. When the coil of the contactor is powered, the contacts are attracted, and the electrical circuit is connected. According to the driving mode of the coil, contactors are mainly divided into three categories: AC contactors, DC contactors, and AC / DC universal contactors.

[0003] AC contactors use AC power to drive the coil of the contactor, thereby controlling the closing or opening of the contactor's contacts. Due to the natural voltage zero-crossing characteristic of AC power, high-frequency vibration occurs during the attraction process of the contactor, resulting in significant noise. In addition, AC power is generally obtained directly from the power grid, and fluctuations in the grid voltage can easily affect the attraction effect of the contactor, and even cause the coil to burn out.

[0004] DC contactors use DC power to drive the coil of the contactor, thereby controlling the closing or opening of the contactor's contacts. DC contactors do not have the problem of AC zero-crossing, and the noise is relatively small. However, the volume of the DC coil is generally larger, resulting in a relatively large overall volume of the contactor and higher cost.

[0005] AC / DC universal contactors use PWM (Pulse Width Modulation) technology for starting and maintaining, combining the respective advantages of AC and DC contactors. However, due to the introduction of electronic circuits, the EMC (Electromagnetic Compatibility), reliability, and cost are at a great disadvantage compared to AC and DC contactors. CONTENT OF THE INVENTION

[0006] The present application provides a contactor driving circuit and a contactor. Through the design of the contactor driving circuit, the performance of the contactor is improved while the volume and cost of the contactor are controlled, solving the problems of large volume, high cost, and high noise of the currently commonly used contactors.

[0007] In a first aspect, the application provides an alternating current (AC) contactor driving circuit for providing a driving power source for an AC contactor, the AC contactor comprising a contactor coil, a first normally closed contact, and a second normally closed contact, and characterized in that the AC contactor driving circuit further comprises an isolation transformer, a rectifier circuit, and an auxiliary power supply circuit; a secondary side of the isolation transformer is connected to a first end of the first normally closed contact through the rectifier circuit, a second end of the first normally closed contact is connected to a first end of the contactor coil, a second end of the contactor coil is connected to a second end of the second normally closed contact, a first end of the second normally closed contact is connected to an intermediate tap of the secondary side of the isolation transformer; and the auxiliary power supply circuit is connected in parallel with the contactor coil.

[0008] In an implementation, the auxiliary power supply circuit comprises an auxiliary power supply; the AC contactor further comprises a first normally open contact and a second normally open contact; a first end of the auxiliary power supply is connected to a first end of the first normally open contact, a second end of the first normally open contact is connected to a second end of the first normally closed contact; a second end of the auxiliary power supply is connected to a first end of the second normally open contact, a second end of the second normally open contact is connected to a second end of the contactor coil.

[0009] In an implementation, the rectifier circuit is a full-wave rectifier circuit.

[0010] In an implementation, the rectifier circuit comprises a first diode and a second diode; a first end of the isolation transformer is connected to a first end of the first diode, a second end of the first diode is connected to a first end of the first normally closed contact, a second end of the first normally closed contact is connected to a first end of the contactor coil; a second end of the isolation transformer is connected to a first end of the second diode, a second end of the second diode is connected to a first end of the first normally closed contact.

[0011] In an implementation, a control port is arranged between the second end of the first normally closed contact and the first end of the contactor coil.

[0012] In an implementation, the isolation transformer is an AC transformer, a rated voltage of the secondary side of the isolation transformer is , and a rated voltage of the contactor coil is . .

[0013] In an implementation, the auxiliary power supply is a direct current (DC) low-voltage power supply.

[0014] In a second aspect, the application further provides an AC contactor, comprising a driving module, wherein the driving module comprises the AC contactor driving circuit described above; and the driving module is detachably connected with the AC contactor.

[0015] In a third aspect, the application further provides another AC contactor, wherein a driving board is integrated in the AC contactor, and the driving board comprises the AC contactor driving circuit described above.

[0016] Compared with the prior art, the application has at least the following beneficial effects: the AC contactor driving circuit provided by the application provides a stable driving power supply for the AC contactor through an isolation transformer and a rectifier circuit, thereby ensuring the reliability of the contactor. The isolation transformer achieves electrical isolation, thereby ensuring the safety of the circuit. The rectifier circuit adopts a full-wave rectifier circuit, thereby providing a flexible rectification scheme. Further, the double power supply switching is achieved through an auxiliary power supply and auxiliary contacts of the contactor, without the need of additional control of a controller, thereby simplifying the structure and improving the switching reliability. The main contacts and the auxiliary contacts of the contactor are mechanically connected, thereby improving the switching reliability. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings needed in the embodiments. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0018] Figure 1 is a prior art AC contactor driving circuit schematic diagram;

[0019] Figure 2 is an AC contactor driving circuit schematic diagram provided by an embodiment of the application;

[0020] Figure 3 is a rectifier circuit output voltage waveform schematic diagram provided by an embodiment of the application. DETAILED DESCRIPTION

[0021] In order to make the technical personnel in the art better understand the technical solutions of the application, the following will combine the drawings in the embodiments of the application to clearly and completely describe the technical solutions in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without any creative effort should belong to the protection scope of the application.

[0022] The AC contactor is an automatic switching electrical appliance that connects or disconnects the main circuit of a motor or load. It uses electromagnetic force to open or close the contacts, is suitable for frequent operation, remote control of high-voltage circuits, and has low-voltage release protection. It plays an important role in industrial automation, power systems, household appliances, and other fields. Its reliability and stability are important for ensuring the safe operation of the circuit and the normal operation of the equipment.

[0023] The AC contactor is usually composed of an electromagnetic coil, contacts (including fixed contacts and movable contacts), springs, connectors, and a housing. When the electromagnetic coil is energized, it generates an electromagnetic force that causes the movable contacts to contact or separate from the fixed contacts, thereby controlling the on-off of the circuit.

[0024] Currently, the AC contactor usually uses the mains to provide starting current for the coil, which generates a large electromagnetic force to overcome the spring force of the AC contactor, thereby completing the attraction of the movable and fixed contacts. After the AC contactor completes the attraction action, the electromagnetic force required to maintain the attraction is small. At this time, if the mains is still used as the power source for the coil, it is easy to cause the coil to run for a long time under overvoltage, resulting in excessive temperature rise and even burning out of the coil. Therefore, in some application scenarios, an auxiliary power source is usually provided to switch between the mains and the auxiliary power source after the AC contactor is started, and the auxiliary power source is used to power the coil. Referring to Figure 1 , Figure 1 is a prior art AC contactor driving circuit diagram. When the first control switch K1 is closed, the mains is used to energize the coil, and the movable and fixed contacts of the AC contactor are attracted. At this time, the second control switch K2 is closed, and the first control switch K1 is opened, and the auxiliary power source is used to power the coil. Diodes D21 and D22 are also needed on the auxiliary power supply circuit to prevent the mains and the auxiliary power source from interfering with each other while ensuring continuous power supply to the coil. As can be seen, the current AC contactor needs two control ports, i.e. the first control switch K1 and the second control switch K2, to control the start and maintenance of the AC contactor, and the actions of the two control ports need to be controlled in a certain sequence. The control program is complicated, and the two power sources are not completely decoupled physically. If the program is wrong or the internal diode is damaged, the two will be directly connected, causing extensive damage to the components.

[0025] The present application provides an AC contactor driving circuit, which solves the problems existing in the current AC contactor. The AC contactor driving circuit provided by the present application will be described in detail below with reference to the accompanying drawings.

[0026] Referring to Figure 2 , Figure 2is a kind of AC contactor drive circuit schematic diagram provided by the embodiment of the application.The AC contactor drive circuit includes isolation transformer T, rectifier circuit 100 and auxiliary power supply circuit 200, the secondary side of isolation transformer T is connected with the first end of first normally closed contact NC1 through rectifier circuit 100, the second end of first normally closed contact NC1 is connected with the first end of contactor coil km, the second end of contactor coil km is connected with the second end of second normally closed contact NC2, and the first end of second normally closed contact NC2 is connected with the intermediate tap of the secondary side of isolation transformer T.

[0027] When AC contactor is not started, first normally closed contact NC1 and second normally closed contact NC2 are in closed state.Isolation transformer T secondary side and rectifier circuit 100, first normally closed contact NC1, AC contactor coil km, second normally closed contact NC2 form complete power supply circuit.When isolation transformer T works, AC contactor coil km is powered, and AC contactor completes attraction, and when AC contactor completes attraction, first normally closed contact NC1 and second normally closed contact NC2 are disconnected, AC power supply circuit is disconnected, and AC contactor drive coil is powered by auxiliary power supply circuit 200 to maintain the attraction state of AC contactor.Specifically, continuing to refer to Figure 2 As shown in the figure, auxiliary power supply circuit 200 includes auxiliary power supply DC, and the AC contactor further includes first normally open contact NO1 and second normally open contact NO2.The first end of auxiliary power supply DC is connected with the first end of first normally open contact NO1, the second end of first normally open contact NO1 is connected with the second end of first normally closed contact NC1, the second end of auxiliary power supply DC is connected with the first end of second normally open contact NO2, and the second end of second normally open contact NO2 is connected with the second end of contactor coil km.

[0028] When AC contactor is attracted, first normally closed contact NC1 and second normally closed contact NC2 are disconnected, AC power supply circuit of AC contactor coil km is cut off, first normally open contact NO1 and second normally open contact NO2 are closed, and auxiliary power supply DC power supply circuit is connected.At this time, AC contactor coil is powered by auxiliary power supply DC to maintain the attraction state of AC contactor.Among them, auxiliary power supply DC is DC voltage power supply.The voltage level of auxiliary power supply DC is low, and the power consumption is small, which reduces the vibration noise of AC contactor while maintaining the attraction state of contactor.

[0029] The primary side of isolation transformer T is connected with AC power supply, which includes but is not limited to power grid (i.e.mains), power generation equipment and AC battery, etc.Isolation transformer T not only provides stable driving power supply for AC contactor, but also realizes electrical isolation, which isolates power supply and load, reduces electrical interference, and improves the stability and safety of circuit.

[0030] It can be understood that in the AC contactor drive circuit, since the second end of the AC contactor coil km is connected to the middle tap of the isolation transformer T, the voltage across the AC contactor coil km should be half of the secondary side voltage of the isolation transformer T, that is, when the rated voltage of the secondary side of the isolation transformer T is When the rated voltage of the contactor coil is Should be For example, when the rated voltage of the secondary side of the isolation transformer T is 220V, the rated voltage of the AC contactor coil should be 110V. In some embodiments, when the AC contactor drive circuit provided in this embodiment is used, when a 220V AC power supply is used and the transformation ratio k of the isolation transformer T is 1:1, an AC contactor with a rated power supply of 110V should be selected. When the transformation ratio k of the isolation transformer T is 1:2, the rated voltage of the secondary side of the isolation transformer T is 440V, and a 220V AC contactor should be selected. Accordingly, when an AC contactor with a rated voltage of 110V is selected, a rated voltage of 12V for the auxiliary power supply DC is sufficient for normal operation of the AC contactor. When an AC contactor with a rated voltage of 220V is selected, the rated voltage of the auxiliary power supply DC should be 24V.

[0031] Reference Figure 2 As shown, in some embodiments, a control port EN is provided between the second end of the first normally closed contact NC1 and the first end of the contactor coil km. The control port EN can be used to control the AC power supply circuit of the AC contactor coil km. Specifically, when the AC contactor coil km is not energized, the first normally closed contact NC1 and the second normally closed contact NC2 are in a closed state. At this time, if the control port EN is in an open state, the AC power supply circuit of the AC contactor coil km is disconnected, and the AC contactor cannot be started. When the control port EN is closed, the AC contactor coil power supply circuit is closed, the AC contactor coil is energized, and the contactor is attracted. In actual application scenarios, by sending a control signal to the control port EN, the AC contactor coil power supply circuit can be controlled, and the control of the AC contactor can be achieved in turn, so that the AC contactor can be used in remote or automated control scenarios, improving convenience and flexibility.

[0032] Continue to refer to Figure 2As shown, in some embodiments, the second end of the first normally open contact NO1 is connected with the second end of the first normally closed contact NC1, at this time, the control port EN is located between the second normally open contact NO1 and the AC contactor coil km, and the control of the DC power supply loop of the AC contactor coil km can be realized by controlling the control port EN. Therefore, it can be known that the control port EN can realize the control of the AC contactor during the starting and maintaining process of the AC contactor. When it is needed to release the contactor, only by making the AC contactor control port EN disconnected, the AC contactor coil km can be de-energized, so as to realize the release of the contactor contact.

[0033] In some other embodiments, when there is no remote control requirement, a manual switch can also be arranged in the auxiliary power supply circuit 200 to complete the release of the contactor, and the AC power supply loop of the AC contactor coil can indirectly control the starting of the AC contactor by controlling the isolation transformer.

[0034] With reference to the foregoing description, the auxiliary power supply circuit 200 can realize the control of the AC contactor coil km by controlling the control port EN, and the release of the contactor contact can be realized by making the control port EN disconnected. Figure 2 As shown, the rectifier circuit 100 is a full-wave rectifier circuit, and as an example, the rectifier circuit 100 includes a first diode D1 and a second diode D2. The first end of the isolation transformer T is connected with the first end of the first diode D1, the second end of the first diode D1 is connected with the first end of the first normally closed contact NC1, the second end of the first normally closed contact NC1 is connected with the first end of the contactor coil km; the second end of the isolation transformer T is connected with the first end of the second diode D2, and the second end of the second diode D2 is connected with the first end of the first normally closed contact NC1.

[0035] With reference to the foregoing description, the auxiliary power supply circuit 200 can realize the control of the AC contactor coil km by controlling the control port EN, and the release of the contactor contact can be realized by making the control port EN disconnected. Figure 3As shown, due to the single-phase conductivity of the diode, the alternating current is always alternating in one direction after being rectified by the board bridge, and the current direction flowing into the AC contactor coil is the same as the direction of the auxiliary power DC flowing into the AC contactor coil. Specifically, when the secondary side voltage of the isolation transformer T is in the positive half cycle, the first diode D1 is turned on, the second diode D2 is turned off, and the current flows from the first end of the AC contactor coil km to the second end of the AC contactor coil km. When the secondary side voltage of the isolation transformer T is in the negative half cycle, the first diode D1 is turned off, the second diode D2 is turned on, and the current still flows from the first end of the AC contactor coil km to the second end of the AC contactor coil km. The current of the auxiliary power DC always flows from the first end of the AC contactor coil km to the second end of the AC contactor coil km. Therefore, the AC contactor coil km can output a certain holding force at the switching moment, avoiding the occurrence of jitter, that is, avoiding the rapid oscillation of the AC contactor between the two states of attraction and release. If it is a conventional alternating current, that is, the current flowing through the AC contactor coil km has a positive half cycle and a negative half cycle, when switching, it happens to be in the negative half cycle, the current direction of the AC contactor coil km is opposite to the subsequent auxiliary power DC current direction, then at the current commutation, the end in the holding force loss occurs, and thus the jitter occurs.

[0036] The AC contactor driving circuit provided by the application realizes the conversion from AC power supply to DC auxiliary power supply through the auxiliary contacts (the first normally closed contact, the second normally closed contact, the first normally open contact, and the second normally open contact) of the AC contactor itself, maintains the attraction state of the contactor, avoids the disconnection of the AC contactor due to the disconnection of the self-supplying circuit, and because the main contact and the auxiliary contact of the contactor are mechanically connected, the switching reliability is high, and the stability and reliability of the circuit are ensured.

[0037] The working principle of the AC contactor driving circuit provided by the application is described again below to deepen the understanding, and the specific description is as follows:

[0038] When the AC contactor is started, the driving current is provided through the isolation transformer and the rectifier circuit, and when the AC contactor is not started, the first normally closed contact NC1 and the second normally closed contact NC2 are in the closed state. When the contactor control port EN is closed, the AC contactor coil is powered, the AC contactor is attracted, that is, the main contact of the AC contactor is attracted, at this time, the first normally closed contact NC1 and the second normally closed contact NC2 are disconnected, the AC power supply of the AC contactor coil is cut off, the first normally open contact NO1 and the second normally open contact NO2 are closed, the DC power supply of the AC contactor coil is connected, and the AC contactor is maintained in the attracted state. When the AC contactor needs to be released, the control contactor control port EN is disconnected, the AC contactor coil is powered off, the AC contactor main contact is disconnected, the first normally closed contact NC1 and the second normally closed contact NC2 return to the closed state, and the first normally open contact NO1 and the second normally open contact NO2 return to the open state, thereby preparing for the next start.

[0039] In a second aspect, the application provides an AC contactor, which comprises a driving module, and the driving module comprises the AC contactor driving circuit described above. The driving module is detachably connected with the AC contactor, so that the driving part and the AC contactor body are easily separated and recombined, thereby facilitating maintenance and replacement. As an example, a jack is arranged on the AC contactor body, and a pin is arranged on the driving module. The jack and the pin are connected through plug-in cooperation, so that the AC contactor driving circuit and the AC contactor coil are electrically connected.

[0040] In a third aspect, the application provides another AC contactor, which has a driving board integrated therein, and the driving board comprises the AC contactor driving circuit described above. The integrated design makes the structure of the AC contactor more compact, reduces external connection and wiring, and improves the overall reliability and stability. At the same time, since the driving circuit and the contactor body are integrated, the installation and debugging process is more convenient, the cost is reduced, and the overall performance and user experience of the product are improved.

[0041] It is easy to understand that, based on the several embodiments provided by the application, the skilled in the art can combine, split, recombine, etc. the embodiments of the application to obtain other embodiments, and these embodiments do not exceed the protection scope of the application.

[0042] The above specific embodiments have further detailed the purposes, technical solutions and beneficial effects of the embodiments of the application. It should be understood that the above is only a specific embodiment of the application, and is not used to limit the protection scope of the embodiments of the application. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the embodiments of the application should be included in the protection scope of the embodiments of the application.

Claims

1. An AC contactor drive circuit for providing a drive power for an AC contactor, the AC contactor comprising a contactor coil, a first normally closed contact and a second normally closed contact, characterized by, The isolation transformer, the rectifier circuit and the auxiliary power supply circuit are further included. The secondary side of the isolation transformer is connected with the first end of the first normally closed contact through the rectifier circuit, the second end of the first normally closed contact is connected with the first end of the contactor coil, the second end of the contactor coil is connected with the second end of the second normally closed contact, and the first end of the second normally closed contact is connected with the intermediate tap of the secondary side of the isolation transformer. The auxiliary power supply circuit is connected with the contactor coil in parallel.

2. An AC contactor drive circuit according to claim 1, wherein The auxiliary power supply circuit includes an auxiliary power supply, and the alternating current contactor further includes a first normally open contact and a second normally open contact. The first end of the auxiliary power supply is connected with the first end of the first normally open contact, and the second end of the first normally open contact is connected with the second end of the first normally closed contact. The second end of the auxiliary power supply is connected with the first end of the second normally open contact, and the second end of the second normally open contact is connected with the second end of the contactor coil.

3. An AC contactor drive circuit according to claim 1, wherein The rectifier circuit is a full-wave rectifier circuit.

4. An AC contactor drive circuit according to claim 1, wherein The rectifier circuit includes a first diode and a second diode. The first end of the isolation transformer is connected with the first end of the first diode, the second end of the first diode is connected with the first end of the first normally closed contact, and the second end of the first normally closed contact is connected with the first end of the contactor coil. The second end of the isolation transformer is connected with the first end of the second diode, and the second end of the second diode is connected with the first end of the first normally closed contact.

5. The AC contactor drive circuit of claim 2, wherein, The second end of the first normally closed contact is provided with a control port between the first end of the contactor coil.

6. The AC contactor drive circuit of claim 1, wherein, The isolation transformer is an alternating current transformer, a rated voltage of the secondary side of the isolation transformer is , and a rated voltage of the contactor coil is . .

7. The AC contactor drive circuit of claim 1, wherein, The auxiliary power supply is a direct current low-voltage power supply.

8. An AC contactor characterized by The drive module includes the alternating current contactor drive circuit according to any one of claims 1-7, and the drive module is detachably connected with the alternating current contactor.

9. An AC contactor characterized by The drive board is integrated in the alternating current contactor, and the drive board includes the alternating current contactor drive circuit according to any one of claims 1-7.

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