Drive circuit for stably starting mining contactor and mining contactor

Abstract

The invention relates to a drive circuit for stably starting a mining contactor and the mining contactor, and belongs to the field of mining contactors. The drive circuit comprises an input end used for being connected with an alternating current power supply, an output end used for being connected with a mining contactor coil, a large-current power supply branch circuit used for switching-on starting and a small-current power supply branch circuit used for keeping a switching-on state. The large-current power supply branch comprises a first rectifier bridge with one end connected with the input end and the other end connected with the output end, the on-off end of a first switch tube is connected in series between the positive electrode of the first rectifier bridge and the positive electrode of the output end, and the controlled end of the first switch tube is used for being connected with a controller; the primary side of the step-down transformer is connected with the input end, the secondary side of the step-down transformer is connected with the input side of a second rectifier bridge, and the output side of the second rectifier bridge is connected with the output end. According to the invention, the mining contactor can be stably started, and the operation rejection phenomenon is reduced.

Description

Technical Field

[0001] The invention relates to a driving circuit for stably starting a mining contactor and a mining contactor, belonging to the field of mining contactors. Background Art

[0002] As an important device in power equipment applications, contactors play an important role in power transmission in engineering applications in various industries. In 3.6 kilovolt (KV) mining contactors, safe and stable control of the equipment is crucial to equipment safety and mining environment safety.

[0003] At present, most 3.6KV mining contactors are composed of control circuits, and the closing start and closing state of the mining contactor are only completed by the normally closed contacts of the mining contactor. However, as the normally closed contacts are used for a longer time or because of their own structural reasons, when the mining contactor needs to be closed, the normally closed contacts cannot be in the closed state or are immediately disconnected in the closed state. This will cause the mining contactor to refuse to move and fail to close, which is prone to safety accidents; there may also be cases where the normally closed contacts are always in the closed state and cannot be disconnected, which will cause a large current to power the contactor coil of the mining contactor, which is easy to cause the mining contactor to burn out. Summary of the invention

[0004] The object of the present invention is to provide a driving circuit for stably starting a mining contactor and a mining contactor, so as to solve the problem that the mining contactor is prone to refusal to operate in the prior art.

[0005] To achieve the above object, the solution of the present invention includes: A driving circuit for stably starting a mining contactor of the present invention comprises: an input end for connecting an AC power supply, an output end for connecting a mining contactor coil, a large current power supply branch for closing and starting, and a small current power supply branch for maintaining a closed state; The high current power supply branch includes a first rectifier bridge having one end connected to the input end and the other end connected to the output end, a first switch tube is connected in series between the positive electrode of the first rectifier bridge and the positive electrode of the output end, and the controlled end of the first switch tube is used to connect to the controller; The small current power supply branch includes a primary side connected to the input end, a secondary side connected to a step-down transformer at the input side of the second rectifier bridge, and an output side of the second rectifier bridge connected to the output end.

[0006] Furthermore, a normally closed contact of a mining contactor is connected in parallel to the on / off end of the first switch tube.

[0007] Furthermore, a conduction and cutoff end of a second switch tube is connected in series on a common line connecting the negative electrode of the first rectifier bridge and the negative electrode of the second rectifier bridge to the negative electrode of the output end, and the controlled end of the second switch tube is used to connect to a controller.

[0008] Furthermore, the controller is used to control the first switch tube and the second switch tube to close after receiving the closing command, and control the first switch tube to open after a preset time; The preset time is determined according to the closing time characteristics of the mining contactor.

[0009] Furthermore, it also includes: a first voltage sampling circuit connected to both ends of the input end and used for collecting the voltage of the AC power supply.

[0010] Furthermore, it also includes: a second voltage sampling circuit connected to both ends of the output end and used for collecting the voltage of the output end.

[0011] Furthermore, a current sensor for collecting the current at the output end is connected in series to a common line connecting the negative electrode of the first rectifier bridge and the negative electrode of the second rectifier bridge to the negative electrode of the output end.

[0012] Furthermore, it also includes: a first current limiting resistor connected in series between the controller and the first switch tube for current limiting; and a second current limiting resistor connected in series between the controller and the second switch tube for current limiting.

[0013] Furthermore, it also includes: a varistor connected to both ends of the input end for overvoltage protection; The first rectifier bridge includes a full-bridge rectifier bridge; the second rectifier bridge includes a half-bridge rectifier bridge.

[0014] A mining contactor of the present invention comprises the above-mentioned driving circuit for stably starting the mining contactor.

[0015] The beneficial effects of the present invention are as follows: as a pioneering invention, the present invention uses the first switch tube and the first rectifier bridge to allow the first switch tube to be turned on when the mining contactor needs to be closed. Since the first rectifier bridge is directly connected to the input end of the AC power supply, when the first switch tube is turned on, the contactor coil of the mining contactor is powered by a large current, which can achieve the purpose of stable starting and closing. At the same time, by using the second rectifier bridge and the step-down transformer, the step-down transformer provides a small current to the mining contactor to maintain the closed state of the mining contactor, which can further make the mining contactor in a stable closed state. Therefore, the refusal of the mining contactor can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a driving circuit for stably starting a mining contactor provided by an embodiment of the present invention; Figure 2is a schematic diagram of the structure of a controller provided by an embodiment of the present invention; Figure 3 is a schematic diagram of the structure of a first voltage sampling circuit and a second voltage sampling circuit provided by an embodiment of the present invention; Figure 4 The embodiment of the present invention provides Figure 1 Schematic diagram of the conduction of the driving circuit in the positive half cycle of AC; Figure 5 The embodiment of the present invention provides Figure 1 Schematic diagram of the conduction of the driving circuit in the negative half cycle of AC; Figure 6 The embodiment of the present invention provides Figure 1 Schematic diagram of the conduction when the driving circuit in generates a small current. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0018] The concept of the present invention is to connect the input end of the AC power supply, the output end of the contactor coil for the mine, a large current power supply branch for closing and starting, and a small current power supply branch for maintaining the closed state; the large current power supply branch includes a first rectifier bridge with one end connected to the input end and the other end connected to the output end, the positive pole of the first rectifier bridge and the positive pole of the output end are connected in series with the on-off end of the first switch tube, and the controlled end of the first switch tube is used to connect the controller; the small current power supply branch includes a primary side connected to the input end, a secondary side connected to the step-down transformer on the input side of the second rectifier bridge, and the output side of the second rectifier bridge connected to the output end. By using the first switch tube and the first rectifier bridge, the first switch tube is turned on when the mine contactor needs to be closed. Since the first rectifier bridge is directly connected to the input end of the AC power supply, when the first switch tube is turned on, the contactor coil of the mine contactor is powered by a large current, so that the purpose of stable starting and closing can be achieved. At the same time, by using the second rectifier bridge and the step-down transformer, the step-down transformer provides a small current to the mining contactor to maintain the closed state of the mining contactor, which can further make the mining contactor in a stable closed state.

[0019] An embodiment of a driving circuit for stably starting a mining contactor: Combine the following Figure 1-Figure 3 A driving circuit for stably starting a mining contactor provided by an embodiment of the present invention is described.

[0020] Figure 1 is a schematic diagram of a structure of a driving circuit for stably starting a mining contactor provided by an embodiment of the present invention, such as Figure 1As shown, the drive circuit includes: an input end for connecting to an AC power supply, an output end for connecting to a mining contactor coil, a high-current power supply branch for closing and starting, and a low-current power supply branch for maintaining a closed state; the high-current power supply branch includes a first rectifier bridge having one end connected to the input end and the other end connected to the output end, a first switch tube Q1 is connected in series between the positive pole of the first rectifier bridge and the positive pole of the output end, and a controlled end of the first switch tube Q1 is used to connect to a controller (not shown); the low-current power supply branch includes a primary side connected to the input end, a secondary side connected to a step-down transformer T1 on the input side of a second rectifier bridge, and an output side of the second rectifier bridge is connected to the output end.

[0021] Among them, the input end includes the live wire AC-L (i.e. the positive pole of the input end) and the neutral wire AC-N (i.e. the negative pole of the input end); the output end includes the coil + (i.e. the positive pole of the output end) and the coil - (i.e. the negative pole of the output end).

[0022] Among them, the first rectifier bridge includes a full-bridge rectifier bridge B1; the second rectifier bridge includes a half-bridge rectifier bridge; the full-bridge rectifier bridge B1 is a diode-type full-bridge rectifier bridge; the half-bridge rectifier bridge is a diode-type half-bridge rectifier bridge, and the conduction direction of the diode points to the coil +.

[0023] Among them, the first switch tube Q1 can be a metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET), and can also be a bipolar junction transistor (Bipolar junction transistor, BJT), etc., and the present invention does not specifically limit this. In order to reduce cost and impedance, the embodiment of the present invention takes the first switch tube Q1 as a MOS tube as an example for exemplary description. The first switch tube Q1 can be an NPN MOS tube or a PNP MOS tube. The present invention does not specifically limit this. The first switch tube Q1 is a PNP MOS tube as an example for exemplary description.

[0024] When the first switch tube Q1 is a PNP MOS tube, the source of the first switch tube Q1 is connected to the positive electrode of the full-bridge rectifier B1, the drain of the first switch tube Q1 is connected to the positive electrode of the output end, and the gate of the first switch tube Q1 is connected to the drive control 1 end of the controller.

[0025] As an optional implementation, a driving circuit for stably starting a mining contactor provided in an embodiment of the present invention further includes: a normally closed contact S1 (NC) of the mining contactor connected in parallel to both ends of the source and drain of the first switch tube Q1. The controlled end of the normally closed contact S1 (NC) of the mining contactor is connected to the closing position end of the controller. The closing and opening of the normally closed contact S1 (NC) of the mining contactor can respectively reflect the closing start position and the closing holding position of the mining contactor.

[0026] When the normally closed contact S1 (NC) is included, when the controller receives a closing command, it controls the first switch tube Q1 to be turned on and the normally closed contact S1 (NC) to be closed; after the contactor is closed, the normally closed contact S1 (NC) is disconnected, and the first switch tube Q1 continues to remain closed. After a preset time, the first switch tube Q1 is disconnected.

[0027] The preset time depends on the closing time characteristics of the mining contactor.

[0028] In order to understand the current condition of the contactor coil of the mining contactor in real time, as an optional implementation mode, a driving circuit for stably starting the mining contactor provided in an embodiment of the present invention also includes: a current sensor STK1 connected in series on a common line connecting the negative pole of the full-bridge rectifier bridge B1 and the negative pole of the half-bridge rectifier bridge to the negative pole of the output end, and the current sensor STK1 is also connected to the current sampling port 1 of the controller.

[0029] In order to understand the voltage conditions at both ends of the AC power supply in real time, as an optional implementation, a driving circuit for stably starting a mining contactor provided in an embodiment of the present invention also includes: a first voltage sampling circuit U1 connected to both ends of the neutral line AC-N and the live line AC-L.

[0030] In order to understand the current condition of the contactor coil of the mining contactor in real time, as an optional implementation, a driving circuit for stably starting the mining contactor provided in an embodiment of the present invention also includes: a second voltage sampling circuit U2 connected to the positive and negative terminals of the output end.

[0031] The schematic diagram of the structure of the first voltage sampling circuit U1 and the second voltage sampling circuit U2 can be referred to as Figure 2 , Figure 2 is a schematic diagram of the structure of a first voltage sampling circuit and a second voltage sampling circuit provided by an embodiment of the present invention, such as Figure 2 As shown, Figure 2 (a) in FIG. 1 is a schematic diagram showing the structure of the first voltage sampling circuit U1. Figure 2 (b) in FIG. 1 is a schematic diagram showing the structure of the second voltage sampling circuit U2 .

[0032] like Figure 2As shown in (a), the first voltage sampling circuit U1 includes a first operational amplifier. The embodiment of the present invention does not specifically limit whether the in-phase input terminal (i.e., the "+" pole) of the first operational amplifier is connected to the live wire AC-L, or the inverting input terminal (i.e., the "-" pole) of the first operational amplifier is connected to the live wire AC-L; the embodiment of the present invention does not specifically limit whether the in-phase input terminal of the first operational amplifier is connected to the neutral wire AC-N, or the inverting input terminal of the first operational amplifier is connected to the neutral wire AC-N; as long as one input terminal of the first operational amplifier is connected to the live wire AC-L, and the other input terminal is connected to the neutral wire AC-N. The output terminal of the first operational amplifier is connected to the voltage sampling 1 terminal of the controller.

[0033] like Figure 2 As shown in (b), the second voltage sampling circuit U2 includes a second operational amplifier. Whether the in-phase input terminal (i.e., "+" pole) of the second operational amplifier is connected to the positive pole (i.e., "coil +") of the contact coil loop, or the inverting input terminal (i.e., "-" pole) of the second operational amplifier is connected to the positive pole of the contact coil loop, the embodiment of the present invention does not specifically limit this; whether the in-phase input terminal of the second operational amplifier is connected to the negative pole (i.e., "coil -") of the contact coil loop, or the inverting input terminal of the second operational amplifier is connected to the negative pole of the contact coil loop, the embodiment of the present invention does not specifically limit this; as long as one input terminal of the second operational amplifier is connected to the positive pole of the contact coil loop, and the other input terminal is connected to the negative pole of the contact coil loop. The output terminal of the second operational amplifier is connected to the voltage sampling 2 terminal of the controller.

[0034] In order to prevent the AC power supply voltage from being too high and causing damage to the subsequent circuit, as an optional implementation, a driving circuit for stably starting a mining contactor provided in an embodiment of the present invention also includes: a varistor voltage RV1 connected across the neutral line AC-N and the live line AC-L.

[0035] In order to prevent the mining contactor from being damaged by excessive voltage of the AC power supply, excessive voltage of the contactor coil of the mining contactor or excessive current, as an optional implementation, a driving circuit for stably starting a mining contactor provided in an embodiment of the present invention also includes: a second switch tube Q2 is connected in series on a common line connecting the negative electrode of the full-bridge rectifier bridge B1 and the negative electrode of the half-bridge rectifier bridge to the negative electrode of the output end, and the controlled end of the second switch tube Q2 is used to connect to a controller.

[0036] Among them, the second switch tube Q2 can be a MOS tube, or a BJT tube, etc., and the present invention does not specifically limit this. In order to reduce cost and impedance, the embodiment of the present invention takes the second switch tube Q2 as an example of a MOS tube for exemplary description. The second switch tube Q2 can be an NPN MOS tube or a PNP MOS tube, and the present invention does not specifically limit this. The second switch tube Q2 is a PNP MOS tube as an example for exemplary description.

[0037] When the second switch tube Q2 is a PNP MOS tube, the source of the second switch tube Q2 is connected to the coil -, the drain of the second switch tube Q2 is respectively connected to the negative electrode of the full-bridge rectifier bridge B1 and the negative electrode of the half-bridge rectifier bridge through the current sensor STK1, and the gate of the second switch tube Q2 is connected to the drive control 2 end of the controller.

[0038] When the second switch tube Q2 is included, when the controller receives a closing instruction, it controls the first switch tube Q1 to be turned on, the normally closed contact S1 (NC) to be closed, and the second switch tube Q2 to be turned on; after the contactor is closed, the normally closed contact S1 (NC) is disconnected, the first switch tube Q1 and the second switch tube Q2 continue to remain turned on, and after a preset time, the first switch tube Q1 is disconnected and the second switch tube Q2 remains turned on.

[0039] In order to prevent excessive current from damaging the first switch tube Q1, as an optional implementation, a drive circuit for stable starting of a mining contactor provided in an embodiment of the present invention also includes: a first current limiting resistor R1 for current limiting connected in series between the gate of the first switch tube Q1 and the drive control 1 terminal of the contactor.

[0040] In order to prevent excessive current from damaging the second switch tube Q2, as an optional implementation, a drive circuit for stable starting of a mining contactor provided in an embodiment of the present invention also includes: a second current limiting resistor R2 for current limiting connected in series between the gate of the second switch tube Q2 and the drive control 2 end of the contactor.

[0041] The resistance values ​​of the first current limiting resistor R1 and the second current limiting resistor R2 can be selected according to actual conditions, and the present invention does not impose any special limitation on this.

[0042] The structure of the controller can be referred to Figure 3 , Figure 3 is a schematic diagram of the structure of a controller provided by an embodiment of the present invention, such as Figure 3 As shown, the controller includes a current sampling 1 port, a voltage sampling 1 port, a voltage sampling 2 port, a closing position port, a drive control 1 port and a drive control 2 port.

[0043] As an optional implementation, the controller includes a main control chip for executing various programs.

[0044] Combine the following Figure 4-Figure 6 The working principle of a driving circuit for stably starting a mining contactor provided by an embodiment of the present invention is described.

[0045] When the mining contactor needs to be started, a large current is used to start the mining contactor. When the controller receives the start command of the mining contactor, that is, when the first voltage sampling circuit collects power input between the live wire AC-L and the neutral wire AC-N, the controller will detect the voltage through the voltage sampling port 1. When the controller determines that the voltage at both ends of the AC power source transmitted by the voltage sampling port 1 is within the normal power supply range, the first switch tube Q1 is controlled to be turned on through the drive control port 1. At this time, the normally closed contact S1 (NC) of the mining contactor is in a closed state; the second switch tube Q2 is controlled to be turned on through the drive control port 2.

[0046] The normal power supply range may be [70 volts (V), 285V] or other ranges, which is not particularly limited in the present invention.

[0047] At this time, the conduction status of the drive circuit in the positive half cycle of AC can be referred to Figure 4 , Figure 4 The embodiment of the present invention provides Figure 1 The conduction diagram of the driving circuit in the positive half cycle of AC is shown in Figure 4 As shown, the current I provided by the AC power supply 电 From the live wire AC-L, through the fifth diode D5 on the full-bridge rectifier, the normally closed contact S1 (NC) and the switch tube Q1, it flows into the coil +, coil -, the switch tube Q2, the current sensor STK1, the second diode D2 and the first diode D1, and then flows into the coil + again; at the same time, the current I provided by the AC power supply 电 After coming out of the current sensor STK1, it also flows to the neutral line AC-N through the third diode D3 on the full-bridge rectifier. In addition, under the action of the step-down transformer T1, there will also be an induced current I on the secondary winding of the step-down transformer T1. T1 , the induced current I T1 One part flows back to the secondary winding of the step-down transformer T1 through the second diode D2, and the other part flows into the positive pole of the contactor coil loop through the second diode D2 and the first diode D1. Since the contactor coil has current provided by the AC power supply, the mining contactor can realize high current starting and closing.

[0048] The conduction status of the drive circuit in the negative half cycle of AC can be referred to Figure 5 , Figure 5 The embodiment of the present invention provides Figure 1 The schematic diagram of the conduction of the driving circuit in the negative half cycle of AC is shown in Figure 5 As shown, the current I provided by the AC power supply电 From the neutral line AC-N, through the fourth diode D4 on the full-bridge rectifier B1, the normally closed contact S1 (NC) and the first switch tube Q1, it flows into the coil +, coil -, the second switch tube Q2, the current sensor STK1, the second diode D2 and the first diode D1, and then flows into the coil + again; at the same time, the current I provided by the AC power supply 电 After coming out of the current sensor STK1, it also flows to the live wire AC-L through the sixth diode D6 on the full-bridge rectifier B1. Due to the reverse cutoff effect of the second diode D2, there is no current on the secondary winding of the step-down transformer T1. Since there is current provided by the AC power supply on the contactor coil, the mining contactor can achieve high current starting and closing.

[0049] After the mining contactor is closed, the controller controls the normally closed contact S1 (NC) to be disconnected through the closing position port. In order to ensure that the mining contactor can stably achieve high-current startup and closing, after the controller collects the closing position signal of the mining contactor through the closing position port, it determines the preset time length according to the closing time characteristics of the mining contactor through the drive control 1 port, and controls the first switch tube Q1 to be turned off after the preset time length.

[0050] After the normally closed contact S1 (NC) is disconnected and the first switch tube Q1 is turned off, the mining contactor enters a low current closing holding state. The conduction status of the drive circuit can be referred to Figure 6 , Figure 6 The embodiment of the present invention provides Figure 1 The conduction diagram of the driving circuit in FIG. 1 when generating a small current is shown in FIG. Figure 6 As shown, since the normally closed contact S1 (NC) and the first switch tube Q1 are both disconnected (in Figure 6 In the figure, the normally closed contact S1 (NC) is marked as disconnected, and the first switch tube Q1 is disconnected), then the full-bridge rectifier B1 fails, and the AC power supply stops supplying power to the contact coil. At this time, the contact coil is powered by the half-bridge rectifier bridge and the step-down transformer T1. Specifically, the inductive current I on the secondary winding of the step-down transformer T1 T1 A part of it flows back to the secondary winding of the step-down transformer T1 through the second diode D2, and the other part flows into the coil + and coil - after being rectified by the second diode D2 and the first diode D1, and then flows into the coil + again after passing through the second switch tube Q2, the current sensor STK1, the second diode D2 and the first diode D1. Since there is a half-bridge rectifier bridge and the current provided by the step-down transformer T1 on the contactor coil, the mining contactor can enter the low-current closing holding state.

[0051] Whether a large current is used to start the closing of the mining contactor, or a small current is used to keep the mining contactor in the closed state, in order to reduce damage to the drive circuit due to overvoltage or overcurrent, the controller is also used to detect the current on the contact coil and the voltage at both ends of it in real time, and detect the voltage at both ends of the AC power supply in real time. When the voltage at both ends of the AC power supply exceeds the first threshold, the controller controls the second switch tube Q2 to be turned off through the drive control 2 port, that is, the contact coil is cut off; or, when the current on the contact coil exceeds the second threshold, the controller controls the second switch tube Q2 to be turned off through the drive control 2 port, that is, the contact coil is cut off; or, when the voltage at both ends of the contact coil exceeds the third threshold, the controller controls the second switch tube Q2 to be turned off through the drive control 2 port, that is, the contact coil is cut off.

[0052] Among them, the first threshold value can be 285V or other values, and the present invention does not make any special limitation on this; the second threshold value and the third threshold value can be determined according to the coil of the mining contactor, and the present invention does not make any special limitation on this.

[0053] A driving circuit for stably starting a mining contactor provided by an embodiment of the present invention comprises: an input end for connecting an alternating current power supply, an output end for connecting a mining contactor coil, a large current power supply branch for closing and starting, and a small current power supply branch for maintaining a closed state; the large current power supply branch comprises a first rectifier bridge having one end connected to the input end and the other end connected to the output end, a first switch tube is connected in series between the positive pole of the first rectifier bridge and the positive pole of the output end, and the controlled end of the first switch tube is used to connect a controller; the small current power supply branch comprises a primary side connected to the input end, a secondary side connected to a step-down transformer on the input side of the second rectifier bridge, and an output side of the second rectifier bridge connected to the output end. By using the first switch tube and the first rectifier bridge, the first switch tube is turned on when the mining contactor needs to be closed. Since the first rectifier bridge is directly connected to the input end of the alternating current power supply, when the first switch tube is turned on, the contactor coil of the mining contactor is powered by a large current, so that the purpose of stable starting and closing can be achieved. At the same time, by using the second rectifier bridge and the step-down transformer, the step-down transformer provides a small current to the mining contactor to maintain the closed state of the mining contactor, which can further make the mining contactor in a stable closed state. Therefore, the refusal of the mining contactor can be reduced, and the stable operation and service life of the mining contactor can be improved.

[0054] An embodiment of a mining contactor: A mining contactor provided in an embodiment of the present invention includes a driving circuit for stably starting the mining contactor.

[0055] For the introduction of the driving circuit for stable starting of a mining contactor, please refer to the relevant description in the aforementioned "an embodiment of a driving circuit for stable starting of a mining contactor", which will not be repeated here.

[0056] A mining contactor provided in an embodiment of the present invention can achieve the same beneficial effects as the aforementioned driving circuit for stably starting a mining contactor, which will not be described in detail here.

Claims

1. A driving circuit for stably starting a mining contactor, characterized in that: include: An input end for connecting to an AC power source, an output end for connecting to the mining contactor coil, a high current power supply branch for closing and starting, and a low current power supply branch for maintaining a closed state; The high-current power supply branch includes a first rectifier bridge having one end connected to the input end and the other end connected to the output end, a first switch tube having an on / off end connected in series between the positive electrode of the first rectifier bridge and the positive electrode of the output end, and a controlled end of the first switch tube being used to connect to a controller; The small current power supply branch includes a step-down transformer with a primary side connected to the input end and a secondary side connected to the input side of the second rectifier bridge, and an output side of the second rectifier bridge is connected to the output end.

2. The driving circuit for stable starting of a mining contactor according to claim 1, characterized in that: The on / off end of the first switch tube is also connected in parallel with the normally closed contact of the mining contactor.

3. The driving circuit for stable starting of a mining contactor according to claim 1, characterized in that: The on / off end of the second switch tube is connected in series on a common line connecting the negative electrode of the first rectifier bridge and the negative electrode of the second rectifier bridge to the negative electrode of the output end, and the controlled end of the second switch tube is used to connect to a controller.

4. The driving circuit for stable starting of a mining contactor according to claim 3, characterized in that: The controller is used to control the first switch tube and the second switch tube to close after receiving a closing command, and control the first switch tube to open after a preset time; Wherein, the preset time is determined according to the closing time characteristics of the mining contactor.

5. The driving circuit for stable starting of a mining contactor according to claim 3, characterized in that: Also includes: A first voltage sampling circuit connected to both ends of the input end and used for collecting the voltage of the AC power supply.

6. The driving circuit for stable starting of a mining contactor according to claim 3, characterized in that: Also includes: A second voltage sampling circuit connected to both ends of the output end and used for collecting the voltage of the output end.

7. The driving circuit for stable starting of a mining contactor according to claim 3, characterized in that: A current sensor for collecting current at the output end is connected in series to a common line connecting the negative electrode of the first rectifier bridge and the negative electrode of the second rectifier bridge to the negative electrode of the output end.

8. The driving circuit for stable starting of a mining contactor according to claim 3, characterized in that: Also includes: A first current limiting resistor is connected in series between the controller and the first switch tube for current limiting; and a second current limiting resistor is connected in series between the controller and the second switch tube for current limiting.

9. The driving circuit for stable starting of a mining contactor according to any one of claims 1 to 8, characterized in that: Also includes: A varistor connected to both ends of the input terminal for overvoltage protection; The first rectifier bridge includes a full-bridge rectifier bridge; the second rectifier bridge includes a half-bridge rectifier bridge.

10. A contactor for mining, characterized in that: The invention comprises a driving circuit for stably starting a mining contactor as described in any one of claims 1 to 9.

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