A contactless switch for high DC inductive loads based on electromagnet

Abstract

The present application discloses a high DC inductive load contactless switch based on an electromagnet, comprising: a thyristor control circuit, wherein the thyristor control circuit comprises an electromagnet YA, four single-phase thyristors SCR1, SCR2, SCR3, and SCR4. The present application provides a high DC inductive load contactless switch based on an electromagnet, which adopts thyristors SCR1, SCR2, SCR3, and SCR4 to form an on-off control circuit and a discharge circuit of the electromagnet YA, thereby abandoning the arrangement of a contactor using a mechanical contact mechanism in the prior art on the circuit of the electromagnet YA, which not only ensures the electromagnet YA's multiple operating functions such as forward conduction, live power-off, and reverse power-on during the lifting process, but also prevents the electromagnet YA from repeatedly turning on and off, causing the contacts to produce arcing, sparking, noise, and other problems, thereby making the switch of the present application have a longer service life.

Description

Technical Field

[0001] The invention relates to the technical field of power switches, in particular to an electromagnet-based high DC inductive load contactless switch. Background Art

[0002] The main parts of a DC lifting electromagnet are a magnet, an iron core, and a conductor. The magnet can generate a strong magnetic field. When the current is turned on, the electromagnet will firmly absorb the steel objects and lift them to the designated place. When the current is turned off, the magnetism disappears and the steel objects are put down.

[0003] The DC lifting electromagnet is a high inductive load. When it is turned off, it will generate several times more reverse electromotive force, arcing, sparking, and noise between the contacts, which will cause the contactor to be easily damaged. Usually, in order to prevent the contactor contacts from burning when turning off, a discharge resistor circuit must be added to the back end of the contactor. However, it is still easy to burn the contacts when opening and closing frequently. Summary of the invention

[0004] The present application proposes a high DC inductive load contactless switch based on an electromagnet, which has the advantages of avoiding arcing, sparking and noise generated when the electromagnet contacts are disconnected, and is used to solve the problem that the electromagnet contactor is easily damaged.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a high DC inductive load contactless switch based on an electromagnet, comprising: a thyristor control circuit, the thyristor control circuit comprising an electromagnet YA, four single-phase thyristors SCR1, SCR2, SCR3, and SCR4, the electromagnet YA and the thyristor SCR1 are connected in series to form a main circuit, the two ends of the main circuit are point P and point N, point P1 is located between point P and point N, one end of the electromagnet YA is connected to point P, and the other end of the electromagnet YA is connected to point P1. The anode of thyristor SCR1 is connected to point P1, the cathode of thyristor SCR1 is connected to point N, the cathode of thyristor SCR2 is connected to the cathode of thyristor SCR1, and the anode of thyristor SCR2 is connected to the X wire; thyristor SCR3 is connected in parallel with thyristor SCR1, the anode of thyristor SCR3 is connected to point N, and the cathode of thyristor SCR3 is connected to point P1; thyristor SCR4 is connected in parallel with electromagnet YA, the anode of thyristor SCR4 is connected to point P1, and the cathode of thyristor SCR4 is connected to point P.

[0006] Further, a forward voltage is applied to PN and the thyristor SCR1 is turned on, so that the thyristor control circuit is forward-conducted.

[0007] Further, the thyristors SCR2 and SCR4 are turned on, and a high voltage is applied to X, so that the thyristor control circuit is powered on and turned off.

[0008] Further, a reverse voltage is applied to PN, and the thyristor SCR3 is turned on, so that the thyristor control circuit is reversely conducted.

[0009] Furthermore, the thyristor SCR4 is replaced by the diode D2, and the thyristor SCR3 branch is cancelled, thereby forming a thyristor control circuit A.

[0010] Furthermore, the thyristor SCR2 branch is eliminated to form a thyristor control circuit B.

[0011] Furthermore, the anode of the thyristor SCR4 is connected to the discharge resistor R2 to form a thyristor control circuit C.

[0012] The present invention has the following beneficial effects:

[0013] 1. The present application provides an electromagnet-based high DC inductive load contactless switch, which adopts thyristors SCR1, SCR2, SCR3, and SCR4 to form an on-off control circuit and a discharge circuit of the electromagnet YA, thereby abandoning the arrangement of a contactor using a mechanical contact mechanism in the circuit of the electromagnet YA in the prior art. This not only ensures the electromagnet YA's multiple operating functions such as forward conduction, energized shutdown, and reverse energization during the lifting process, but also prevents the contacts from arcing, sparking, and noise caused by repeated on and off of the electromagnet YA, thereby extending the service life of the switch of the present application.

[0014] 2. The present application provides an electromagnet-based high DC inductive load contactless switch, which adjusts the thyristor control circuit according to actual conditions to form thyristor control circuit A, thyristor control circuit B, and thyristor control circuit C, respectively, thereby increasing the flexibility and robustness of the circuit system of the switch of the present application and expanding the applicable field of the circuit system of the switch of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which constitute a part of the specification, illustrate embodiments disclosed in the present application and, together with the description, serve to explain the principles disclosed in the present application.

[0016] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

[0017] Figure 1 Schematic diagram of the circuit composition of the first embodiment of the present application; wherein, Figure a0 is a schematic diagram of the contactor control circuit composition, and Figure b0 is a schematic diagram of the thyristor control circuit composition;

[0018] Figure 2 This is a schematic diagram of forward power-on in the first embodiment of the present application; wherein, FIG a1 is a schematic diagram of forward power-on in the contactor control circuit, and FIG b1 is a schematic diagram of forward power-on in the thyristor control circuit;

[0019] Figure 3This is a schematic diagram of power-on shutdown of the first embodiment of the present application; wherein a2 represents a schematic diagram of power-on shutdown of the contactor control circuit, and b2 represents a schematic diagram of power-on shutdown of the thyristor control circuit;

[0020] Figure 4 Schematic diagram of reverse power supply in the first embodiment of the present application; wherein, FIG a3 is a schematic diagram of reverse power supply in the contactor control circuit, and FIG b3 is a schematic diagram of reverse power supply in the thyristor control circuit;

[0021] Figure 5 This is a schematic diagram of the circuit composition of the second embodiment of the present application;

[0022] Figure 6 This is a schematic diagram of the circuit composition of the third embodiment of the present application;

[0023] Figure 7 This is a schematic diagram of the circuit composition of Example 4 of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] Embodiment 1

[0026] See also Figure 1 As shown, Figure a0 is a schematic diagram of the contactor control circuit composition, and Figure b0 is a schematic diagram of the thyristor control circuit composition.

[0027] As shown in Figure a0, the contactor control circuit includes: electromagnet YA, contactor KM, resistor R1, and diode D1. The electromagnet YA and contactor KM are connected in series to form a main circuit. The two ends of the main circuit are point P and point N respectively. The terminal voltage is applied to point P and point N. The diode D1 and resistor R1 are connected in series and then connected in parallel with the electromagnet YA. The cathode of the diode D1 is connected in series with point P.

[0028] As shown in Figure b0, the thyristor control circuit includes: an electromagnet YA, four single-phase thyristors SCR1, SCR2, SCR3, and SCR4. The electromagnet YA and the thyristor SCR1 are connected in series to form a main circuit. The two ends of the main circuit are point P and point N respectively, and point P1 is located between point P and point N. One end of the electromagnet YA is connected to point P, and the other end of the electromagnet YA is connected to point P1. The anode of the thyristor SCR1 is connected to point P1, and the cathode of the thyristor SCR1 is connected to point N; the cathode of the thyristor SCR2 is connected to the cathode of the thyristor SCR1, and the anode of the thyristor SCR2 is connected to the X wire; the thyristor SCR3 is connected in parallel with the thyristor SCR1, the anode of the thyristor SCR3 is connected to point N, and the cathode of the thyristor SCR3 is connected to point P1; the thyristor SCR4 is connected in parallel with the electromagnet YA, the anode of the thyristor SCR4 is connected to point P1, and the cathode of the thyristor SCR4 is connected to point P.

[0029] See attached Figure 2 Figure a1 shows the schematic diagram of the contactor control circuit being powered in the forward direction, and Figure b1 shows the schematic diagram of the thyristor control circuit being powered in the forward direction.

[0030] As shown in Figure a1, PN is added with a positive voltage, that is, P is the positive pole and N is the negative pole. The contactor KM is closed, the electromagnet YA is positively excited, and the direction of the current is from P to N, that is, the direction of Ia1 shown in Figure a1. In the application of this circuit, when the contactor KM is closed, the collision between the contacts will form a loud noise.

[0031] As shown in Figure a2, a forward voltage is added to PN, and a trigger signal is applied to the control electrode g of the thyristor SCR1. The anode and cathode of the thyristor SCR1 are turned on, the electromagnet YA is forwardly excited, and the direction of the current is from point P to point N, that is, the direction of Ib1 shown in Figure b1.

[0032] See attached Figure 3 Figure a2 shows the schematic diagram of the contactor control circuit being powered on and shutting down, and Figure b2 shows the schematic diagram of the thyristor control circuit being powered on and shutting down.

[0033] When multiple electromagnets are used together, they need to be controlled independently in groups, so the circuit of each electromagnet YA needs to be energized and closed. As shown in Figure a2, the contactor KM is disconnected, the circuit from point P to point N is disconnected, that is, the current in the direction of Ia1 shown in Figure a2 is disconnected, and the electromagnet YA generates a reverse electromotive force due to the inductance. The negative pole of the reverse electromotive force is the end of the electromagnet YA connected to point P, and the positive pole of the reverse electromotive force is the end of the electromagnet YA connected to point P1. The reverse current flows along the electromagnet YA, point P1, resistor R1, diode D1, point P, and electromagnet YA, that is, the direction shown by Ia2 in Figure a2. After the above-mentioned contactor KM is disconnected, the conversion of the current from the direction of Ia1 to the direction of Ia2 is not instantaneous, but a process. The specific process is as follows: when the contactor KM is disconnected, the contacts of the contactor will produce dazzling arc light due to arcing, and will make a loud "bang" sound. The greater the contact distance, the longer the arc light, and the greater the resistance between the contacts. Until the current is transferred from the direction of Ia1 to the direction of Ia2, after the arc light disappears, the circuit of the electromagnet YA is truly closed, and the contacts of the contactor KM are easily damaged under the high temperature of the arc light.

[0034] As shown in Figure b2, a trigger signal is applied to the control electrodes g of the thyristors SCR2 and SCR4 to turn on the thyristors SCR2 and SCR4. After the thyristor SCR2 is turned on, a high voltage higher than point P1 is applied at point X to make the potential at point N higher than that at point P1. The voltage direction on the thyristor SCR1 is from the cathode to the anode of the thyristor SCR1, that is, a reverse voltage is applied to the thyristor SCR1, thereby achieving instantaneous shutdown of the thyristor SCR1 without sound or light. The reverse current formed by the reverse electromotive force of the electromagnet YA flows along the electromagnet YA, point P1, thyristor SCR4, point P, and electromagnet YA to suppress the generation of high voltage, that is, the direction of Ib2 shown in Figure b2.

[0035] See attached Figure 4 As shown, Figure a3 shows the schematic diagram of reverse power on the contactor control circuit, and Figure b3 shows the schematic diagram of reverse power on the thyristor control circuit. When the electromagnet YA is positively excited, it is immediately reversely excited, and the reverse excitation time is usually 1 to 5 seconds.

[0036] As shown in Figure a3, PN is added with reverse voltage, that is, N is the positive pole and P is the negative pole. The contactor KM is closed, and the reverse circuit forms two loops. The directions of the currents in the two loops are respectively Ia3 and Ia4. The current in the Ia3 direction forms a loop through point N, electromagnet YA, point P, and point N. The Ia3 direction loop is used for reverse excitation of electromagnet YA; the current in the Ia4 direction forms a loop through point N, resistor R1, diode D4, point P, and point N. In the Ia4 direction loop, the current passes through resistor R1, causing resistor R1 to generate heat.

[0037] As shown in Figure b3, PN is added with reverse voltage, that is, N is the positive pole and P is the negative pole, and a trigger signal is applied to the control pole g of the thyristor SCR3, so that the thyristor SCR3 is turned on. The reverse current forms a loop along point N, thyristor SCR3, point P1, electromagnet YA, point P, and point N, that is, the direction of Ib3 in the figure. The reverse current is used for reverse excitation of electromagnet YA. There is only one reverse loop in this circuit, and there is no load in the loop, so energy consumption can be reduced.

[0038] Embodiment 2

[0039] See attached Figure 5 As shown, the difference from the first embodiment is that when the reverse excitation system is not provided in the control system of the electromagnet YA, the thyristor SCR4 is replaced by the diode D2, the thyristor SCR3 branch is cancelled, and the thyristor control circuit A is formed.

[0040] When the thyristor control circuit A is forward-conducted, a forward voltage is applied to PN, that is, P is the positive pole and N is the negative pole. A trigger signal is applied to the control pole g of the thyristor SCR1, the thyristor SCR1 is turned on, and the electromagnet YA is forward-excited.

[0041] When the thyristor control circuit A is powered off, a trigger signal is applied to the control electrode g of the thyristor SCR2, and the thyristor SCR2 is turned on. After the thyristor SCR2 is turned on, a high voltage higher than point P1 is applied at point X to make the potential at point N higher than that at point P1, so as to apply a reverse voltage to the thyristor SCR1, thereby realizing the instantaneous shut-off of the thyristor SCR1 without sound or light. The reverse current formed by the reverse electromotive force of the electromagnet YA flows along the electromagnet YA, point P1, diode D2, point P, and electromagnet YA to form a loop.

[0042] Embodiment 3

[0043] See attached Figure 6 As shown, the difference from the first embodiment is that if the control circuit of the electromagnet YA is not provided with a live shutdown function, the thyristor SCR2 branch is cancelled to form a thyristor control circuit B.

[0044] When the thyristor control circuit B is forward-conducted, a forward voltage is applied to PN, that is, P is the positive pole and N is the negative pole. A trigger signal is applied to the control pole g of the thyristor SCR1, the thyristor SCR1 is turned on, and the electromagnet YA is forward-excited.

[0045] When the thyristor control circuit B is reversely conducted, a reverse voltage is applied to PN, that is, N is the positive pole and P is the negative pole, and a trigger signal is applied to the control electrode g of the thyristor SCR3, so that the thyristor SCR3 is turned on, and the reverse current forms a loop along point N, thyristor SCR3, point P1, electromagnet YA, point P, and point N.

[0046] Embodiment 4

[0047] See attached Figure 7 As shown, the difference from the first embodiment is that: if it is allowed to set a discharge resistor in the discharge circuit, the discharge resistor R2 is connected to the anode of the thyristor SCR4 to form a thyristor control circuit C.

[0048] When the thyristor control circuit C is forward-conducted, a forward voltage is added to PN, and a trigger signal is applied to the control electrode g of the thyristor SCR1. The thyristor SCR1 is turned on, the electromagnet YA is forward-excited, and the direction of the current is from P to N.

[0049] When the thyristor control circuit C is powered off, a trigger signal is applied to the control electrodes g of the thyristors SCR2 and SCR4 to turn on the thyristors SCR2 and SCR4. After the thyristor SCR2 is turned on, a high voltage higher than point P1 is applied at point X to make the potential at point N higher than that at point P1, and a reverse voltage is applied to the thyristor SCR1, thereby achieving an instantaneous shut-off of the thyristor SCR1 without sound or light. The reverse current formed by the reverse electromotive force of the electromagnet YA flows along the electromagnet YA, point P1, resistor R2, thyristor SCR4, point P, and electromagnet YA to form a loop.

[0050] When the thyristor control circuit C is powered on in reverse, a reverse voltage is applied to PN, that is, N is the positive pole and P is the negative pole, and a trigger signal is applied to the control pole g of the thyristor SCR3, so that the thyristor SCR3 is turned on. The reverse current forms a loop along point N, thyristor SCR3, point P1, electromagnet YA, point P, and point N, and the electromagnet YA is reversely excited.

Claims

1. A high DC inductive load contactless switch based on an electromagnet, characterized in that: include: The thyristor control circuit comprises an electromagnet YA, four single-phase thyristors SCR1, SCR2, SCR3 and SCR4. The electromagnet YA and the thyristor SCR1 are connected in series to form a main circuit. The two ends of the main circuit are point P and point N respectively. Point P1 is located between point P and point N. One end of the electromagnet YA is connected to point P, and the other end of the electromagnet YA is connected to point P1. The anode of thyristor SCR1 is connected to point P1, and the cathode of thyristor SCR1 is connected to point N. The cathode of thyristor SCR2 is connected to the cathode of thyristor SCR1, and the anode of thyristor SCR2 is connected to the X wire; thyristor SCR3 is connected in parallel to thyristor SCR1, the anode of thyristor SCR3 is connected to point N, and the cathode of thyristor SCR3 is connected to point P1; thyristor SCR4 is connected in parallel to the electromagnet YA, the anode of thyristor SCR4 is connected to point P1, and the cathode of thyristor SCR4 is connected to point P.

2. The electromagnet-based high DC inductive load contactless switch according to claim 1, characterized in that: A forward voltage is applied to PN and the thyristor SCR1 is turned on, causing the thyristor control circuit to conduct forward.

3. The electromagnet-based high DC inductive load contactless switch according to claim 2, characterized in that: The thyristors SCR2 and SCR4 are turned on, and a high voltage is applied to X, so that the thyristor control circuit is powered on and turned off.

4. The electromagnet-based high DC inductive load contactless switch according to claim 1, characterized in that: A reverse voltage is applied to PN, and the thyristor SCR3 is turned on, causing the thyristor control circuit to conduct in the reverse direction.

5. The electromagnet-based high DC inductive load contactless switch according to claim 1, characterized in that: The thyristor SCR4 is replaced by the diode D2, and the thyristor SCR3 branch is cancelled to form a thyristor control circuit A.

6. The electromagnet-based high DC inductive load contactless switch according to claim 1, characterized in that: Cancel the thyristor SCR2 branch to form thyristor control circuit B.

7. The electromagnet-based high DC inductive load contactless switch according to claim 1, characterized in that: The anode of the thyristor SCR4 is connected to the discharge resistor R2 to form a thyristor control circuit C.

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