CN201038084Y - Permanent magnetism no-arc AC contactor - Google Patents

Abstract

A permanent magnet and no-arc ac contactor belongs to the field of contactor. The utility model comprises a thyristor and a control module, a moving contact, a static contact, a main contact terminal, a movable scaffolding, a keeper, a core, a coil, a neodymium-ferric-boron permanent magnet, a shell and a base. The control module of the thyristor module and the control module comprises a control unit, a switching module, an energy-store module and an IGBT module. The control unit is respectively connected with the thyristor module, the switching module, the energy-store module and the IGBT module. One end of the IGBT module is connected with any phase of a three-phase voltage by the coil, the other end is connected with the other phase of the three-phase voltage. Two ends of the switching module and the energy-store module are all connected with the coil. The thyristor is connected with the three-phase voltage by a three-phase selecting switch. The utility model has the advantages of simple structure, unchanged overall dimension of original contactor, easily realized technique; no-noise operation and no arc switching and so on. The power saving rate is up to over 90 percent, which greatly increases the electrical endurance of the contactor.

Description

A permanent magnet arcless AC contactor

technical field

The utility model belongs to the field of AC contactors, in particular to a permanent magnet arcless AC contactor.

Background technique

When the traditional AC contactor is working, an arc will be generated during the pull-in and break-off process, and the coil must be energized to keep the contactor in the pull-in state after the contactor is closed. When the circuit is turned on and off, there are shortcomings such as strong arcs on the main contacts, which not only causes a lot of waste of electric energy, pollutes the surrounding environment, but also greatly reduces the electrical life of the contactor.

Over the years, electrical workers have carried out a lot of work to improve various performances of contactors, such as energy saving, some use AC pull-in, DC hold; some use high-voltage DC pull-in, low-voltage DC hold, etc., although they have energy-saving functions , but the coil is still energized, it’s just a low-voltage direct current, and the coil still has current, so the energy-saving goal cannot be fully achieved.

In addition, when the arc is generated in the contactor on-off circuit, many researchers have adopted a variety of methods to extinguish the arc, such as increasing the magnetic field to blow the arc, and using a metal grid arc extinguishing chamber. Figure 1 shows a schematic cross-sectional view of the existing AC contactor structure, which includes arc extinguishing cover, arc extinguishing grid, moving contact, static contact, main contact terminal, movable support, conductive rod, armature, iron core, coil , shell and base.

None of the above-mentioned methods can fundamentally eliminate the arc, but only limit and help to extinguish the arc. Although the non-contact switches currently on the market are arc-free products, they are expensive, and because there are no mechanical contacts, they have high conduction loss, poor overload capacity, and are bulky.

Utility model content

Aiming at the problems in the prior art, the utility model provides a permanent magnet power-saving arcless AC contactor.

The structure of the contactor is shown in Figure 2, including silicon controlled rectifiers and control modules, moving contacts, static contacts, main contact terminals, movable brackets, conductive rods, armatures, iron cores, coils, NdFeB permanent magnets, The shell and the base, the shell 10 is covered on the base 11 to form a cavity, in which the iron core 8 is fixed on the center of the base 11, the iron core 8 is concave, the bottom of the iron core has a square groove, and the permanent magnet 13 is placed , the two protruding columns are surrounded by coils 9, the tops of the two columns form a closed magnetic path with the armature 7, the armature 7 is fixedly connected with the movable bracket 6, and the main contact terminal 5 forms a mechanical connection with the static contact 4 through the conductive rod 14 , There are two breakpoints between the moving and static contacts, the thyristor and the control module 12 are installed in the modified arc chute 1 to form a complete contactor.

A NdFeB permanent magnet is placed in the center of the bottom of the contactor iron core 8 of the utility model, and its structure is shown in FIG. 3 .

In the utility model, the thyristor and the control module replace the arc extinguishing device of the existing contactor, which includes a thyristor module and a control module, and the control module is composed of a control unit, a switching module, an energy storage module and an IGBT module , the control unit is connected to the thyristor module, switching module, energy storage module and IGBT module; one end of the IGBT module is connected to any phase of the three-phase voltage through a coil, and the other end is connected to the other phase of the three-phase voltage; the switching module Both ends of the energy storage module are connected to the coil; each contact of the contactor is connected in parallel with a pair of anti-parallel unidirectional thyristors, and then respectively connected to the power supply and the load, as shown in Figure 4.

When the contactor of the utility model is working normally, first press the start button SA1, and the control module starts to work, because the inherent pull-in time of the contactor is 20ms, and the control module makes the thyristor module conduct before the contacts of the contactor at 10ms , to achieve arc-free connection; at the same time, the control module turns on the IGBT module connected in series with the contactor coil for 30ms at 10ms, and then turns off the contactor after it is closed, and there is no more current in the coil. At this time, the maintenance of the contactor is improved. After the design, the magnetic flux generated by the NdFeB permanent magnet in the iron core is realized, so that the function of arc-free connection and power-saving and noise-free operation is realized; when the stop button SA2 is pressed and the contactor coil is powered off, the contactor's The inherent release time is 15ms. The switching module first switches the coil of the contactor to the energy storage module, and uses the energy of the energy storage module to reversely demagnetize the permanent magnet in the iron core, so that the contactor starts to release, and at the same time it is controllable The silicon module provides the trigger voltage for 20ms, so that when the contactor contact is about to open for nearly 15ms, due to the sharp increase of the contact resistance, when the voltage drop at both ends of the contact increases to about 8V (less than the arc voltage), because the trigger signal has been Existence, the thyristor changes from the non-working state short-circuited by the contact to the conduction state. This conversion process is extremely short (microseconds). Before the contact is opened, the current flowing through the contact has already transferred to the thyristor. In this way, the contact is almost opened under the condition of no-load breaking, until the thyristor is cut off due to the disappearance of the trigger signal at 20ms, so that the circuit realizes arc-free breaking.

The utility model utilizes the cut-off of the thyristor to realize the disconnection of the circuit, thereby realizing the function of arc-free on-off, and at the same time, the conduction of the circuit is carried by the mechanical contact, which overcomes the high conduction loss and poor overload capacity of the non-contact switch Shortcomings. In addition, the coil of the contactor of the utility model has a large current flowing only at the moment of contactor pull-in and release (no more than 30ms), so as to ensure the pull-in (excitation) and release (demagnetization) of the contactor. Before release, there is no current in the coil. Therefore, the coil after the improved design has great changes in both the number of turns and the wire diameter, saving a lot of copper. The utility model also has the advantages of simple structure, no change of the original contactor dimensions, easy process realization, noiseless operation, etc., and the power saving rate reaches more than 90%, which greatly improves the electrical life of the contactor.

Description of drawings

Figure 1 is a schematic cross-sectional view of an existing AC contactor structure;

Figure 2 is a schematic cross-sectional view of the structure of the utility model contactor;

Fig. 3 is the structural schematic diagram of the magnetic system of the utility model contactor equipped with NdFeB permanent magnets;

Fig. 4 is a functional block diagram of the utility model circuit;

Fig. 5 is the circuit schematic diagram of the specific embodiment of the present utility model,

(a) is the schematic diagram of the control module circuit in the specific embodiment,

(b) is a schematic diagram of the silicon controlled rectifier circuit in the specific embodiment.

In the figure 1——arc extinguishing cover, 2—arc extinguishing grid, 3—moving contact, 4—static contact, 5—main contact terminal, 6—movable bracket, 7—armature, 8—iron core, 9—coil, 10—shell, 11—base, 12—silicon controlled rectifier and control module, 13—NdFeB permanent magnet, 14—conductive rod, 15—control module.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described.

Figure 2 is a schematic cross-sectional view of the structure of this embodiment, which includes silicon controlled rectifiers and control modules, moving contacts, static contacts, main contact terminals, movable supports, conductive rods, armatures, iron cores, coils, NdFeB The permanent magnet, shell and base, among which the thyristor and the control module replace the arc extinguishing part of the existing contactor, and a permanent magnet of NdFeB is added at the bottom of the iron core. The casing 10 is covered on the base 11 to form a cavity. In the cavity, the iron core 8 is fixed on the center of the base 11. The iron core 8 is concave, and the bottom of the iron core has a square groove for placing the permanent magnet 13. Coils 9 surround the two uprights, the tops of the two uprights form a closed magnetic path with the armature 7, the armature 7 is fixedly connected with the movable bracket 6, and the main contact terminal 5 forms a mechanical connection with the static contact 4 through the conductive rod 14. There are two breakpoints between the contacts, and the thyristor and the control module 12 are installed in the modified arc extinguishing cover 1 to form a complete contactor.

Fig. 3 is a schematic structural diagram of the magnetic system in this embodiment.

Figure 5(a) shows the circuit schematic diagram of the control module in this embodiment, in which two relays KA1 and KA2 realize the switching module function, capacitors C3 and D6 realize the energy storage module function, IGBT and YMDZ realize the IGBT module function, U1A, U1B and its peripheral circuits realize the function of the control module, in which the coil of the relay KA1 is directly connected to the 12V power supply, its pair of normally open contacts are respectively connected to the 380V pulsating DC power supply and the collector of the IGBT, and a pair of normally closed contacts are connected to the collector of the IGBT The coil of the contactor is connected; one end of the coil of the relay KA2 is connected to the 12V power supply, and the other end is connected to the collector of the triode Q1, and its two normally open contacts are respectively connected to the AC 380V power supply and the capacitor C3 with the diode D6 in series; the voltage comparator The output terminal of UIA is connected to the base of IGBT through resistor R8, and the two input terminals are connected to R5, R6, R7 and D6, C2 respectively; the output terminal of voltage comparator UIB is connected to the base of transistor Q1 through resistor R4, UIB The output terminal of the IGBT is also connected to the capacitor C2 through the diode D3, and the two input terminals are respectively connected to R1, R2, R3 and C1, D1; the base of the IGBT is connected to the output terminal of the voltage comparator UIA through the resistor R8, and the collector is connected through The diode D6 is connected to the 380V pulsating DC power supply, the emitter is connected to the ground, and a varistor YMDZ is connected in parallel between the emitter and the collector; a diode D1 is connected between the 12V power supply and the ground, and the a and b terminals are respectively connected to those in Figure 5(b) The a', b' ends in the connection.

Figure 5(b) shows the schematic diagram of the silicon controlled rectifier circuit in this embodiment, using a conventional silicon controlled silicon controlled circuit, in which a pair of antiparallel silicon controlled silicon SCRs are connected in parallel at both ends of each phase contact KM, When the contactor coil is energized, the inherent pull-in time of the contactor is about 20ms. The trigger circuit in the figure makes three pairs of anti-parallel silicon controlled rectifiers turn on at 10ms, so that the silicon controlled rectifiers are already ahead of the contacts of the contactor. When the circuit is connected, when the contact is closed within 20 ms, the contact only short-circuits the silicon controlled rectifier. Since the voltage drop of the silicon controlled rectifier is not enough to generate an arc, the function of arc-free connection is realized. When the coil is powered off, the inherent release time of the contactor is about 15ms, and the thyristor trigger circuit keeps the triggering state until 20ms due to the current released by the energy storage capacitor C1, so that when nearly 1 5ms contacts When the contact of the device is about to open, due to the sharp increase of the contact resistance, when the voltage drop across the contact increases to about 8V (less than the arc voltage), since the trigger signal always exists, the thyristor is short-circuited by the contact and does not work. The state changes to the conduction state. This conversion process is extremely short (microsecond level). Before the contact is opened, the current flowing through the contact has been transferred to the thyristor, so that the contact is almost in the no-load breaking condition. It will be turned on until 20ms, and the thyristor will be cut off due to the disappearance of the trigger signal, so that the circuit can realize arc-free breaking.

Claims (2)

1. permanent magnetism Arcless AC Contactor, comprise upper end cover, moving contact, fixed contact, main contact terminal, travel(l)ing rest, conducting rod, armature, iron core, coil, shell and base, it is characterized in that also comprising controllable silicon and control section, permanent magnet, iron core becomes matrix, the iron core bottom has square groove, place permanent magnet, controllable silicon and control section are installed in the upper end cover; Control section is made up of control unit, switching device, energy-storage travelling wave tube and IGBT element in controllable silicon and the control section, and control unit links to each other with controllable silicon part, switching device, energy-storage travelling wave tube and IGBT element respectively; IGBT element one end is connected to any phase in the three-phase voltage by coil, and another links to each other its other end and three-phase voltage; The two ends of switching device and energy-storage travelling wave tube all link to each other with coil; Each two ends, contact of contactor a pair of antiparallel one-way SCR respectively in parallel is connected with load with power supply respectively again.

2. a kind of permanent magnetism Arcless AC Contactor as claimed in claim 1, the coil that it is characterized in that a relay in the described control section circuit directly links to each other with DC power supply, its a pair of normally opened contact links to each other with the collector electrode of Voltage pulsating direct-current supply and IGBT respectively, and a pair of normally-closed contact then links to each other with contactor coil; Coil one end of another relay links to each other with DC power supply, and the other end links to each other with the collector electrode of triode, and two normally opened contact has the electric capacity of diode to link to each other with AC power with string respectively; The output of a voltage comparator links to each other with the base stage of IGBT by resistance, and two inputs link to each other with diode with resistance, electric capacity respectively; The output of another voltage comparator links to each other with the base stage of triode by resistance, and its output also links to each other with electric capacity by diode simultaneously, and two inputs link to each other with diode with resistance, electric capacity respectively; The base stage of IGBT is linked the output of first voltage comparator by resistance, and collector electrode links to each other with Voltage pulsating direct-current supply by diode, and emitter links to each other with ground, a piezo-resistance in parallel between emitter and the collector electrode; Be connected to diode between DC power supply and the ground, a, b end links to each other with a ', the b ' end of controllable silicon partial circuit respectively in the control section circuit.

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