Surge suppression device and coal mining machine

Abstract

The invention provides a surge suppression device which is arranged between a cutting motor and a traction frequency converter of a coal mining machine, the cutting motor is a three-phase power supply, the surge suppression device comprises a first surge suppression unit and a second surge suppression unit, the first surge suppression unit comprises a plurality of piezoresistors connected to the three-phase power supply, and the second surge suppression unit comprises a plurality of voltage dependent resistors connected to the three-phase power supply. The second surge suppression unit comprises a three-phase bridge rectifier circuit which consists of a plurality of diodes and is connected with the three-phase power supply; and the input end and the output end of the three-phase bridge rectifier circuit are respectively connected to the positive end and the negative end of the direct-current bus of the traction frequency converter. Once surge voltage is generated on the line, the surge voltage can be effectively absorbed through the piezoresistor; the peak voltage before the action of the piezoresistor is effectively absorbed through the three-phase bridge rectifier circuit. Therefore, all surge voltages generated on a line can be effectively absorbed through the combination of the piezoresistor and the three-phase bridge rectifier circuit, the surge voltage of a power grid is effectively inhibited, and overvoltage breakdown of the power module is prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of shearers, and particularly relates to a surge suppression device and a shearer including the surge suppression device. Background Art

[0002] With the development of power electronics technology, it has become increasingly possible to miniaturize and design variable frequency drives with low losses, providing the possibility of directly using the input voltage to remove the traction isolation transformer in the shearer. However, this brings other problems, one of which is the problem of voltage surges.

[0003] Currently in the shearer industry, when the cutting motor and the traction variable frequency drive directly use the power supply provided by the mobile transformer, the traction variable frequency drive does not have an isolation transformer for power supply like traditional coal shearers, and the traction variable frequency drive will directly bear the grid surge voltage. Due to the influence of the leakage inductance of the mobile transformer and the distributed inductance of the main cable, the di / dt during the start and stop of the cutting motor will inevitably generate a reverse induced electromotive force on the line inductance, thereby forming a surge voltage. The surge voltage is a voltage spike with an extremely high amplitude (usually several to more than a dozen times the rated voltage) and an extremely short time (usually only dozens of microseconds), and it is easy to break down the power electronic devices due to overvoltage (especially the IGBT or diode on the rectifier side). Summary of the Invention

[0004] The purpose of the present invention is to provide a surge suppression device and a shearer including the surge suppression device for the deficiencies of the prior art. Based on the design of passive devices for dv / dt, it can effectively suppress the grid surge voltage and prevent the power module from being broken down due to overvoltage.

[0005] The present invention provides a surge suppression device, which is arranged between the cutting motor and the traction variable frequency drive of the shearer. The power supply of the cutting motor is a three-phase power supply. The surge suppression device includes a first surge suppression unit and a second surge suppression unit connected in series. The first surge suppression unit includes a plurality of varistors respectively connected to the three-phase power supply. The second surge suppression unit includes a three-phase bridge rectifier circuit composed of a plurality of diodes and connected to the three-phase power supply. The input end and the output end of the three-phase bridge rectifier circuit are respectively connected to the positive and negative ends of the DC bus of the traction variable frequency drive.

[0006] Preferably, the surge suppression device further includes a high-voltage relay connected between the three-phase bridge rectifier circuit and the positive end of the DC bus of the traction variable frequency drive. The high-voltage relay is set to switch to the closed state after the pre-charging of the traction variable frequency drive is completed.

[0007] Preferably, the plurality of varistors are star-connected to the three-phase power supply.

[0008] Preferably, at least one of the varistors is provided on the single-phase line.

[0009] Preferably, the selected type of the varistor is TMOV20RP460E, the number of the varistors is six, and two of the varistors are connected in series on the single-phase line.

[0010] Preferably, a plurality of fast recovery diodes are connected in series on each arm of the three-phase bridge rectifier circuit.

[0011] Preferably, the selected type of the fast recovery diode is DH40-18A, and three of the fast recovery diodes are connected in series on each arm.

[0012] Preferably, the surge suppression device further includes a current-limiting resistor connected between the positive terminal of the DC bus of the high-voltage relay and the traction frequency converter.

[0013] Preferably, the resistance value of the current-limiting resistor is 0-5Ω and the power is 10-60W; and / or, the selected type of the high-voltage relay is GL81AB47L.

[0014] In addition, the present invention further provides a shearer, including a cutting motor, a traction frequency converter, and the surge suppression device according to any of the above solutions, and the surge suppression device is arranged between the cutting motor and the traction frequency converter.

[0015] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0016] The positive and progressive effects of the present invention are as follows:

[0017] According to the surge suppression device and the shearer involved in the present invention, once a surge voltage is generated on the line, the surge voltage can be effectively absorbed through the multiple varistors of the first surge suppression unit; and for the spike voltage before the varistor comes into effect, it can be effectively absorbed through the three-phase bridge rectifier circuit of the second surge suppression unit. In this way, all the surge voltages generated on the line can be effectively absorbed through the varistors and the three-phase bridge rectifier circuit, the surge voltage of the power grid can be effectively suppressed, and the power module can be prevented from being overvoltage breakdown. Description of the Drawings

[0018] Figure 1 is a circuit schematic diagram of the surge suppression device in the embodiment of the present invention.

[0019] Figure 2 is a waveform diagram without a surge suppression device in the prior art.

[0020] Figure 3 is a waveform diagram with a surge suppression device in the embodiment of the present invention. Detailed implementation manners

[0021] The present invention will be further described below in conjunction with the embodiments shown in the drawings.

[0022] <Embodiment>

[0023] As Figure 1 shown, this embodiment discloses a surge suppression device 100, which is arranged between the cutting motors of a shearer (such as Figure 1 M1 and M2 in it are the left and right cutting motors of the shearer respectively) and the traction frequency converter BP1, and is used to absorb the surge voltage generated in the shearer circuit.

[0024] As Figure 1 shown, the surge suppression device 100 includes a first surge suppression unit 10, a second surge suppression unit 20 and a high-voltage relay 30 connected in series.

[0025] The power supply of the cutting motor is a three-phase power supply. The first surge suppression unit 10 includes a plurality of varistors connected to the three-phase power supply respectively (such as Figure 1 RT1 to RT6 shown in it, which are respectively connected to the R, S, T terminals of the three-phase power supply). The plurality of varistors are star-connected with the three-phase power supply, and at least one varistor is provided on a single-phase line.

[0026] In a specific implementation manner, the type selection of the varistor is TMOV20RP460E. The number of varistors included in the first surge suppression unit 10 is six, and two varistors are connected in series on a single-phase line. Through the varistors configured in this way, the surge voltage generated in the shearer circuit can be effectively absorbed more economically and at lower cost.

[0027] The second surge suppression unit 20 includes a three-phase bridge rectifier circuit composed of a plurality of diodes (such as Figure 1 D1 to D18 shown in it) and connected to the three-phase power supply. The input end and the output end of the three-phase bridge rectifier circuit are respectively connected to the positive and negative ends of the DC bus of the traction frequency converter BP1 (such as Figure 1 P and N shown in it). A plurality of fast-recovery diodes are connected in series on each arm of the three-phase bridge rectifier circuit.

[0028] In a specific implementation manner, the type selection of the fast-recovery diode is DH40-18A, and three fast-recovery diodes are connected in series on each arm.

[0029] The high-voltage relay 30 is connected between the three-phase bridge rectifier circuit and the positive end of the DC bus of the traction frequency converter BP1 (such as Figure 1Between the P terminals), the high-voltage relay 30 is set to be switched to the closed state only after the pre-charging of the traction frequency converter BP1 is completed, so as to avoid damage to the diodes D1 to D18 caused by the inrush current at the moment of power-on. In a specific embodiment, the selected type of the high-voltage relay is GL81AB47L.

[0030] In another embodiment, the surge suppression device 100 further includes a current-limiting resistor 40 (such as Figure 1 shown as R1), which is connected between the high-voltage relay 30 and the positive terminal of the DC bus of the traction frequency converter BP1. The resistance value of the current-limiting resistor 40 is between 0 and 5 Ω, and the power is between 10 and 60 W.

[0031] In addition, this embodiment also provides a shearer, including a cutting motor, a traction frequency converter, and the surge suppression device 100 as described above. The surge suppression device 100 is arranged between the cutting motor and the traction frequency converter.

[0032] Based on the above-mentioned surge suppression device, once a surge voltage is generated on the line, through the multiple varistors of the first surge suppression unit, the surge voltage can be effectively absorbed; and for the spike voltage before the varistor comes into play, it can be effectively absorbed through the three-phase bridge rectifier circuit of the second surge suppression unit. In this way, all the surge voltages generated on the line can be effectively absorbed through the varistors and the three-phase bridge rectifier circuit, effectively suppressing the surge voltage of the power grid and preventing the power module from being overvoltage broken down.

[0033] Combined with Figure 1 For example, in the main circuit diagram of the shearer, M1 and M2 are the left and right cutting motors respectively; BP1 is the traction frequency converter, and M3 is the traction motor; since the power supply cable from the mobile transformer to the shearer is relatively long, at least three or four hundred meters at the shortest, the line inductance of the power supply cable cannot be ignored. In the figure, L1 represents the sum of the cable inductance and the output impedance of the mobile transformer; L2 is the input reactor of BP1; P and N of BP1 are the positive and negative terminals of the DC bus of the traction frequency converter.

[0034] When the shearer is working normally, KM1, KM2, and KM3 are closed; I1 and I2 are the currents of the left and right cutting motors respectively. When the shearer fails, KM1 and KM2 are disconnected. Since the current on L1 cannot change suddenly, a reverse induced electromotive force ΔV will inevitably be generated at both ends of L1, where When I1 and I2 are larger, di / dt is larger; L1 is the cable inductance, and when the shearer is in different positions, the value of L1 is different. Usually, the more turns of wire are wound on the cable car, the larger L1 is. When both di / dt and L1 are larger, the generated reverse induced electromotive force is larger, that is, the surge voltage is higher. When the surge voltage ΔV is high enough, it is very easy to overvoltage break down the rectifier side module of the traction frequency converter BP1.

[0035] After adding the surge suppression device 100 described in this embodiment to the shearer, assuming that the surge voltage of the R phase of the three-phase power supply in the main circuit of the shearer is too high and higher than the bus voltage value of the traction frequency converter BP1, the fast recovery diodes D13 to D15 will conduct forward, clamping the highest amplitude voltage at the DC bus value. As Figure 2 and Figure 3 shown, by comparing the two waveform diagrams with and without the surge suppression device, it can be intuitively seen that the surge suppression device of this embodiment can effectively absorb the surge voltage, play an obvious peak clipping effect when the voltage amplitude is too high, achieve the effect of suppressing the surge voltage, and suppress the surge current. The clamping ability of the surge suppression device is determined by the current limiting resistor R1. The smaller the resistance value, the stronger the clamping ability and the stronger the surge suppression ability.

[0036] The surge suppression device of this embodiment is for the 1140V shearer in the scenario without an isolation transformer. It combines voltage-dependent absorption and diode clamping, and effectively utilizes the bus voltage of the frequency converter as the upper limit voltage value for clamping, and can effectively suppress the surge current in the main circuit.

[0037] The protection scope of the present invention is not limited to the above embodiments. Obviously, those skilled in the art can make various changes and deformations to the present invention without departing from the scope and spirit of the present invention. If these changes and deformations fall within the scope of the claims of the present invention and its equivalent technologies, the intention of the present invention also includes these changes and deformations.

Claims

1. A surge suppression device, arranged between the cutting motor and the traction inverter of a coal mining machine, wherein the power supply of the cutting motor is a three-phase power supply, characterized in that: The surge suppression device includes a first surge suppression unit and a second surge suppression unit connected in series, the first surge suppression unit includes a plurality of varistors respectively connected to the three-phase power supply, the second surge suppression unit includes a three-phase bridge rectifier circuit composed of a plurality of diodes and connected to the three-phase power supply, the input and output ends of the three-phase bridge rectifier circuit are respectively connected to the positive and negative ends of the DC bus of the traction inverter.

2. The surge suppression device according to claim 1, characterized in that: The surge suppression device also includes a high-voltage relay connected between the three-phase bridge rectifier circuit and the positive end of the DC bus of the traction inverter, and the high-voltage relay is configured to switch to an energized state after the pre-charging of the traction inverter is completed.

3. The surge suppression device according to claim 2, characterized in that: The plurality of varistors are connected to the three-phase power supply in a star shape.

4. The surge suppression device according to claim 3, characterized in that: At least one varistor is arranged on the single-phase line.

5. The surge suppression device according to claim 4, characterized in that: The type of the varistor is TMOV20RP460E, the number of the varistors is six, and two of the varistors are connected in series on a single-phase line.

6. The surge suppression device according to claim 2, characterized in that: A plurality of fast recovery diodes are connected in series on each bridge arm of the three-phase bridge rectifier circuit.

7. The surge suppression device according to claim 6, characterized in that: The fast recovery diode is selected as DH40-18A, and three fast recovery diodes are connected in series on each bridge arm.

8. The surge suppression device according to claim 2, characterized in that: The surge suppression device also includes a current limiting resistor connected between the high-voltage relay and the positive end of the DC bus of the traction inverter.

9. The surge suppression device according to claim 8, characterized in that: The resistance of the current limiting resistor is 0-5Ω, and the power is 10-60W; and / or the high-voltage relay is GL81AB47L.

10. A coal mining machine, characterized in that: It comprises a cutting motor, a traction inverter and a surge suppression device as claimed in claims 1 to 9, wherein the surge suppression device is arranged between the cutting motor and the traction inverter.

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