Suppression circuit and suppression equipment

Abstract

The invention discloses a suppression circuit and suppression equipment, and relates to the field of semiconductors, according to the scheme, a three-phase filtering unit, a first common-mode filtering module, a second common-mode filtering module and a third common-mode filtering module are arranged between a long cable and an inverter module of a frequency converter, the three common-mode filtering modules are respectively arranged between the three-phase output end of the inversion module and the ground wire, high-frequency common-mode voltage in voltage output to the generator by the frequency converter can be effectively filtered, and the three-phase filtering unit can filter low-frequency voltage in the voltage output to the generator by the frequency converter. According to the scheme, the high-frequency common-mode voltage output to the generator by the frequency converter is filtered, so that the high-amplitude shaft voltage cannot be induced on the rotating shaft of the generator, the bearing current cannot be formed, and the safety of the bearing of the generator is ensured; in addition, when the voltage output by the frequency converter is transmitted to the generator through the cable, no overvoltage is generated on the rotor side of the generator, and the winding insulation pressure of the generator is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a suppression circuit and a suppression device. Background Art

[0002] In modern industry, with the continued advancement of semiconductor device performance, the overall performance of voltage source PWM (Pulse Width Modulation) inverters has continuously improved, leading to an increasingly widespread application. However, despite their widespread use, some significant negative side effects have been observed. For example, in the wind power industry, tower heights of MW-class wind turbines are typically over 70 meters. Placing both the inverter and generator in a nacelle at the top of the tower can complicate installation and commissioning. Therefore, the inverter is typically placed at the bottom of the tower, inevitably requiring long cables to connect the inverter and generator. Because inverters use high-frequency turn-off devices, and because the high-frequency switching power electronics generate strong electromagnetic interference (EMI) on the power supply each time they operate, the high-frequency common-mode voltage generated by the inverter can induce high-amplitude shaft voltages on the generator shaft, generating bearing currents that can damage the generator bearings in a short period of time and shorten the generator's service life. In addition, when the cable reaches a certain length and the cable and motor impedance do not match, the high-frequency common-mode voltage output by the inverter will be transmitted to the generator through the cable, which will generate overvoltage on the rotor side of the generator, aggravating the insulation pressure of the generator winding and making the impact of the above negative effects more significant. Summary of the Invention

[0003] The object of the present invention is to provide a suppression circuit and suppression device. This solution filters out the high-frequency common-mode voltage output by the inverter to the generator, so that no high-amplitude shaft voltage can be induced on the generator shaft, and no bearing current can be generated, thereby ensuring the safety of the generator bearings. In addition, when the voltage output by the inverter is transmitted to the generator via a cable, no overvoltage will be generated on the generator rotor side, greatly reducing the insulation pressure of the generator winding.

[0004] In order to solve the above technical problems, the present invention provides a suppression circuit, comprising: a three-phase filtering unit, a first common-mode filtering module, a second common-mode filtering module, and a third common-mode filtering module;

[0005] The three-phase input terminals of the three-phase filter unit are connected one-to-one with the three-phase output terminals of the inverter module of the frequency converter, and the three-phase output terminals are connected one-to-one with the three-phase input terminals of the long-line cable, and are used to filter out the low-frequency voltage in the three-phase alternating current output by the inverter module, where the frequency of the low-frequency voltage is less than a preset low-frequency threshold voltage;

[0006] The first end of the first common-mode filter module is connected to the first phase output end of the three-phase filter unit and the first phase input end of the long-line cable respectively, and the second end is connected to the ground, and is used to filter out the high-frequency common-mode voltage of the first phase of the three-phase alternating current, where the frequency of the high-frequency common-mode voltage is greater than a preset high-frequency threshold voltage;

[0007] The first end of the second common-mode filter module is connected to the second phase output end of the three-phase filter unit and the second phase input end of the long-line cable respectively, and the second end is connected to the ground, and is used to filter out the high-frequency common-mode voltage of the second phase of the three-phase alternating current;

[0008] The first end of the third common-mode filter module is connected to the third phase output end of the three-phase filter unit and the third phase input end of the long-line cable respectively, and the second end is connected to the ground, so as to filter out the high-frequency common-mode voltage of the third phase of the three-phase alternating current;

[0009] The three-phase output end of the long-line cable is connected to the generator.

[0010] Optionally, the three-phase filtering unit is a three-phase reactor, the three-phase input end of the three-phase reactor is connected one-to-one with the three-phase output end of the inverter module, and the three-phase output end is connected one-to-one with the three-phase input end of the long-line cable.

[0011] Optionally, the first common-mode filtering module is a first capacitor, a first end of the first capacitor is connected to the first phase output end of the three-phase filtering unit and the first phase input end of the long-line cable respectively, and a second end is connected to the ground;

[0012] The second common-mode filtering module is a second capacitor, a first end of the second capacitor is connected to the second phase output end of the three-phase filtering unit and the second phase input end of the long-line cable respectively, and a second end is connected to the ground;

[0013] The third common-mode filtering module is a third capacitor, a first end of which is respectively connected to the third phase output end of the three-phase filtering unit and the third phase input end of the long-line cable, and a second end thereof is connected to the ground.

[0014] Optionally, the first common-mode filtering module further includes: a first resistor;

[0015] The first end of the first resistor is connected to the first phase output end of the three-phase filter unit and the first phase input end of the long-line cable respectively, and the second end is connected to the first end of the first capacitor;

[0016] The second common-mode filtering module further includes: a second resistor;

[0017] The first end of the second resistor is connected to the second phase output end of the three-phase filter unit and the second phase input end of the long-line cable respectively, and the second end is connected to the first end of the second capacitor;

[0018] The third common-mode filtering module further includes: a third resistor;

[0019] The first end of the third resistor is connected to the third phase output end of the three-phase filter unit and the third phase input end of the long-line cable respectively, and the second end is connected to the first end of the third capacitor.

[0020] Optionally, it further includes: a first sub-filtering module, a second sub-filtering module, and a third sub-filtering module;

[0021] The input end of the first sub-filter module is connected to the first phase input end of the three-phase filter unit, and the output end is connected to the first phase output end of the three-phase filter unit, for stabilizing the voltage of the first phase alternating current;

[0022] The input end of the second sub-filter module is connected to the second phase input end of the three-phase filter unit, and the output end is connected to the second phase output end of the three-phase filter unit, for stabilizing the voltage of the second phase alternating current;

[0023] The input end of the third sub-filter module is connected to the third phase input end of the three-phase filter unit, and the output end is connected to the third phase output end of the three-phase filter unit, for stabilizing the voltage of the third phase alternating current.

[0024] Optionally, the first sub-filtering module is a fourth capacitor, a first end of the fourth capacitor is connected to the first phase input end of the three-phase filtering unit, and a second end is connected to the first phase output end of the three-phase filtering unit;

[0025] The second sub-filter module is a fifth capacitor, a first end of the fifth capacitor is connected to the second phase input end of the three-phase filter unit, and a second end of the fifth capacitor is connected to the second phase output end of the three-phase filter unit;

[0026] The third sub-filter module is a sixth capacitor, a first end of the sixth capacitor is connected to the third phase input end of the three-phase filter unit, and a second end of the sixth capacitor is connected to the third phase output end of the three-phase filter unit.

[0027] Optionally, the first sub-filter module further includes: a fourth resistor;

[0028] A first end of the fourth resistor is connected to the first phase input end of the three-phase filter unit, and a second end is connected to the first end of the fourth capacitor;

[0029] The second sub-filter module further includes: a fifth resistor;

[0030] A first end of the fifth resistor is connected to the second phase input end of the three-phase filtering unit, and a second end is connected to the first end of the fifth capacitor;

[0031] The third sub-filter module further includes: a sixth resistor;

[0032] A first end of the sixth resistor is connected to the third phase input end of the three-phase filtering unit, and a second end of the sixth resistor is connected to the first end of the sixth capacitor.

[0033] Optionally, it further includes: a first switch, a second switch, a third switch, a first differential mode filter module, a second differential mode filter module, and a third differential mode filter module;

[0034] A first end of the first switch is connected to the first phase output end of the three-phase filter unit and the first phase input end of the long-line cable, and a second end is connected to the first end of the first differential mode filter module;

[0035] A first end of the second switch is connected to the second phase output end of the three-phase filter unit and the second phase input end of the long-line cable, and a second end of the second switch is connected to the first end of the second differential mode filter module;

[0036] A first end of the third switch is connected to the third phase output end of the three-phase filter unit and the third phase input end of the long-line cable, and a second end is connected to the first end of the third differential mode filter module;

[0037] The second end of the third differential mode filter module is connected to the second end of the first differential mode filter module and the second end of the second differential mode filter module respectively.

[0038] Optionally, also include:

[0039] a fourth switch, wherein a first end of the fourth switch is respectively connected to the second end of the first differential mode filter module, the second end of the second differential mode filter module, and the second end of the third differential mode filter module, and a second end of the fourth switch is connected to the neutral line of the DC input bus of the inverter module.

[0040] In order to solve the above technical problems, the present invention further provides a suppression device, comprising: a housing and the suppression circuit as described above, wherein the suppression circuit is arranged in the housing.

[0041] The purpose of the present invention is to provide a suppression circuit and suppression device. This solution sets a three-phase filter unit, a first common-mode filter module, a second common-mode filter module, and a third common-mode filter module between the long-line cable and the inverter module of the frequency converter. The three common-mode filter modules are respectively set between the three-phase output terminals of the inverter module and the ground wire, and can effectively filter out the high-frequency common-mode voltage in the voltage output from the frequency converter to the generator. The three-phase filter unit filters out the low-frequency voltage in the voltage output from the frequency converter to the generator. By filtering out the high-frequency common-mode voltage output from the frequency converter to the generator, this solution cannot induce a high-amplitude shaft voltage on the generator shaft, and cannot generate bearing current, thereby ensuring the safety of the generator bearings. In addition, when the voltage output from the frequency converter is transmitted to the generator via the cable, it will not generate overvoltage on the generator rotor side, greatly reducing the insulation pressure of the generator winding. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0043] Figure 1 A schematic structural diagram of a suppression circuit provided by the present invention;

[0044] Figure 2 A schematic structural diagram of another suppression circuit provided by the present invention;

[0045] Figure 3 A schematic structural diagram of another suppression circuit provided by the present invention;

[0046] Figure 4 A schematic structural diagram of another suppression circuit provided by the present invention;

[0047] Figure 5 This is a schematic structural diagram of another suppression circuit provided by the present invention. DETAILED DESCRIPTION

[0048] The core of the present invention is to provide a suppression circuit and suppression device. This solution filters out the high-frequency common-mode voltage output by the inverter to the generator, so that no high-amplitude shaft voltage can be induced on the generator shaft, and no bearing current can be generated, thereby ensuring the safety of the generator bearings; in addition, when the voltage output by the inverter is transmitted to the generator via the cable, no overvoltage will be generated on the generator rotor side, greatly reducing the insulation pressure of the generator winding.

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0050] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a suppression circuit provided by the present invention. The suppression circuit includes: a three-phase filter unit 1, a first common-mode filter module 2, a second common-mode filter module 3, and a third common-mode filter module 4;

[0051] The three-phase input terminals of the three-phase filter unit 1 are connected one-to-one with the three-phase output terminals of the inverter module, and the three-phase output terminals are connected one-to-one with the three-phase input terminals of the long-line cable. The filter unit 1 is used to filter out the low-frequency voltage in the three-phase alternating current output by the inverter module, where the frequency of the low-frequency voltage is less than a preset low-frequency threshold voltage.

[0052] The first end of the first common-mode filter module 2 is connected to the first phase output end of the three-phase filter unit 1 and the first phase input end of the long-line cable respectively, and the second end is connected to the ground, and is used to filter out the high-frequency common-mode voltage of the first phase of the three-phase alternating current, where the frequency of the high-frequency common-mode voltage is greater than a preset high-frequency threshold voltage;

[0053] The first end of the second common-mode filter module 3 is connected to the second phase output end of the three-phase filter unit 1 and the second phase input end of the long-line cable, respectively, and the second end is connected to the ground, and is used to filter out the high-frequency common-mode voltage of the second phase of the three-phase alternating current;

[0054] The first end of the third common-mode filter module 4 is connected to the third phase output end of the three-phase filter unit 1 and the third phase input end of the long-line cable, and the second end is connected to the ground, and is used to filter out the high-frequency common-mode voltage of the third phase of the three-phase alternating current;

[0055] The three-phase output end of the long-line cable is connected to the generator.

[0056] In the present invention, it is considered that the high-frequency common-mode voltage generated by the frequency converter will induce a high-amplitude shaft voltage on the generator shaft and form a bearing current, which will damage the bearings of the generator in a short period of time and shorten the service life of the generator. In addition, when the cable reaches a certain length and the cable and motor impedance do not match, the high-frequency common-mode voltage output by the inverter will generate overvoltage on the generator rotor side when it is transmitted to the generator through the cable, exacerbating the insulation pressure of the generator winding. Therefore, this solution adds a three-phase filter unit 1, a first common-mode filter module 2, a second common-mode filter module 3, and a third common-mode filter module 4 between the inverter and the long-line cable. Among them, the first common-mode filter module 2, the second common-mode filter module 3, and the third common-mode filter module 4 are respectively arranged between the inverter module and the ground wire of the inverter, which can effectively filter out the high-frequency common-mode voltage in the voltage output from the inverter to the generator. The three-phase filter unit 1 is arranged between the inverter module of the inverter and the long-line cable, which can filter out the low-frequency voltage in the voltage output from the inverter to the generator. Therefore, this solution not only ensures the safety of the generator bearings, extends the life of the bearings, but also greatly reduces the insulation pressure of the generator winding.

[0057] It should be noted that despite their widespread use, VFDs have been found to have some significant negative effects. The high-frequency common-mode voltage generated by VFDs can induce high-amplitude shaft voltages on the generator shaft, generating bearing currents that can damage the generator's bearings quickly and shorten its service life. High-speed switching power electronic devices generate strong electromagnetic interference with the power supply every time they operate, impacting the normal operation of other control systems or electronic equipment. In MW-class wind turbine systems, tower heights typically exceed 70 meters. Placing both the VFD and generator in a nacelle at the tower's top creates inconvenience in VFD installation and commissioning. Therefore, VFDs are typically placed at the tower's base, inevitably requiring long cables to connect the VFD and generator. Because VFDs use high-frequency turn-off devices, their output pulse voltages exhibit high du / dt. When the cable reaches a certain length and the cable and motor impedances are mismatched, the VFD output pulse voltage, when transmitted through the cable to the generator, can generate overvoltage on the rotor side, exacerbating the insulation stress on the generator windings and further exacerbating these negative effects. The existence of these negative effects reduces system reliability and increases the failure rate, but these are often overlooked by inverter users. The actual losses they bring may exceed the cost of the variable frequency speed regulation system itself. Therefore, studying the negative effects of PWM inverters and their solutions has important theoretical and practical value.

[0058] It's also worth noting that this solution, through the rational design of the reactor, resistor, and capacitor parameters, effectively suppresses the common-mode voltage output by the PWM inverter, improving system reliability. While the maximum rotor-side overvoltage is typically twice the inverter's DC-side voltage, the addition of this filter can suppress the maximum rotor-side overvoltage to 1.2 times the inverter's DC-side voltage. Furthermore, as motor capacity increases, this suppression circuit maintains reliable operation and strong adaptability, provided the device parameters are properly designed.

[0059] This embodiment provides a suppression circuit. This solution includes a three-phase filter unit 1, a first common-mode filter module 2, a second common-mode filter module 3, and a third common-mode filter module 4, disposed between the long-line cable and the inverter module of the frequency converter. The first common-mode filter module 2, the second common-mode filter module 3, and the third common-mode filter module 4 are disposed between the three-phase output terminals of the inverter module and the ground wire, respectively, and can effectively filter out high-frequency common-mode voltages from the voltage output from the frequency converter to the generator. The three-phase filter unit 1 also filters out high-frequency common-mode voltages from the voltage output from the frequency converter to the generator. This solution prevents high-amplitude shaft voltages from being induced on the generator shaft, preventing bearing currents from being generated, thereby ensuring the safety of the generator's bearings. Furthermore, when the voltage output from the frequency converter is transmitted to the generator via the cable, overvoltage is not generated on the generator rotor side, significantly reducing insulation stress on the generator windings.

[0060] Based on the above embodiment:

[0061] As an optional embodiment, the three-phase filter unit 1 is a three-phase reactor, the three-phase input end of the three-phase reactor is connected one-to-one with the three-phase output end of the inverter module, and the three-phase output end is connected one-to-one with the three-phase input end of the long-line cable.

[0062] In the present invention, considering that the reactor can improve the voltage distribution on the long transmission line, absorb the charging capacitive reactive power in the cable line, and the reactor can also effectively prevent the self-excitation resonance phenomenon when the generator is connected to the long line, the three-phase reactor is used as the three-phase filtering unit 1 in this application, thereby improving the reliability of the solution.

[0063] It should also be noted that if Figure 2 As shown, the machine-side power unit is the inverter module of the converter, and the three-phase filter unit 1 adopts a three-phase reactor, wherein the shell of the three-phase reactor is connected to the ground wire.

[0064] As an optional embodiment, the first common-mode filter module 2 is a first capacitor C1, a first end of the first capacitor C1 is connected to the first phase output end of the three-phase filter unit 1 and the first phase input end of the long-line cable, respectively, and a second end is connected to the ground;

[0065] The second common-mode filter module 3 is a second capacitor C2, a first end of which is connected to the second phase output end of the three-phase filter unit 1 and the second phase input end of the long-line cable, and a second end of which is connected to the ground;

[0066] The third common-mode filter module 4 is a third capacitor C3 , a first end of which is connected to the third phase output end of the three-phase filter unit 1 and the third phase input end of the long-line cable, and a second end thereof is connected to the ground.

[0067] In the present invention, considering that the capacitor has a filtering function and the electric energy transmitted from the inverter module of the frequency converter to the generator is three-phase AC electric energy, the present application adopts the first capacitor C1, the second capacitor C2 and the third capacitor C3 as the first common-mode filter module 2, the second common-mode filter module 3 and the third common-mode filter module 4 respectively. In addition, the capacitor also has the advantages of good storage performance, long life, small capacity error, small size, large capacity, good high-frequency characteristics, good frequency stability, low loss, high precision, resistance to high voltage and large current impact, and high reliability.

[0068] As an optional embodiment, the first common-mode filtering module 2 further includes: a first resistor R1;

[0069] A first end of the first resistor R1 is connected to the first phase output end of the three-phase filter unit 1 and the first phase input end of the long-line cable, respectively, and a second end is connected to the first end of the first capacitor C1;

[0070] The second common-mode filtering module 3 further includes: a second resistor R2;

[0071] A first end of the second resistor R2 is connected to the second phase output end of the three-phase filter unit 1 and the second phase input end of the long-line cable, respectively, and a second end is connected to the first end of the second capacitor C2;

[0072] The third common-mode filtering module 4 further includes: a third resistor R3;

[0073] A first end of the third resistor R3 is connected to the third phase output end of the three-phase filter unit 1 and the third phase input end of the long-line cable, respectively, and a second end is connected to the first end of the third capacitor C3.

[0074] In the present invention, considering that the current value corresponding to the electric energy may be high during the process of the inverter transmitting power to the generator, in order to protect the safety of various components in the suppression circuit, this solution additionally provides a first resistor R1, a second resistor R2 and a third resistor R3, and uses each resistor to limit the current of the loop to protect various components in the suppression circuit. In addition, the resistors also have the characteristics of good stability, small negative temperature coefficient, good high-frequency characteristics, less influence by voltage and frequency, small noise electromotive force, stable pulse load, large resistance range, simple manufacturing process, low cost, etc., which are convenient for practical use.

[0075] As an optional embodiment, it further includes: a first sub-filtering module 5, a second sub-filtering module 6, and a third sub-filtering module 7;

[0076] The input end of the first sub-filter module 5 is connected to the first phase input end of the three-phase filter unit 1, and the output end is connected to the first phase output end of the three-phase filter unit 1, and is used to stabilize the voltage of the first phase alternating current;

[0077] The input end of the second sub-filter module 6 is connected to the second phase input end of the three-phase filter unit 1, and the output end is connected to the second phase output end of the three-phase filter unit 1, for stabilizing the voltage of the second phase alternating current;

[0078] The input end of the third sub-filter module 7 is connected to the third phase input end of the three-phase filter unit 1 , and the output end is connected to the third phase output end of the three-phase filter unit 1 , for stabilizing the voltage of the third phase alternating current.

[0079] In the present invention, taking into account that the three-phase AC power transmitted from the inverter to the generator may have unstable voltage or noise during the transmission process, this solution also additionally provides a first sub-filter module 5, a second sub-filter module 6, and a third sub-filter module 7 to stabilize the voltage of the three-wire AC power and filter out the noise in the three-phase AC power to ensure the stability of power transmission and improve the reliability of the solution.

[0080] As an optional embodiment, the first sub-filter module 5 is a fourth capacitor C4, a first end of the fourth capacitor C4 is connected to the first phase input end of the three-phase filter unit 1, and a second end is connected to the first phase output end of the three-phase filter unit 1;

[0081] The second sub-filter module 6 is a fifth capacitor C5, a first end of the fifth capacitor C5 is connected to the second phase input end of the three-phase filter unit 1, and a second end of the fifth capacitor C5 is connected to the second phase output end of the three-phase filter unit 1;

[0082] The third sub-filter module 7 is a sixth capacitor C6 , a first end of the sixth capacitor C6 is connected to the third phase input end of the three-phase filter unit 1 , and a second end of the sixth capacitor C6 is connected to the third phase output end of the three-phase filter unit 1 .

[0083] In the present invention, Figure 3 As shown, considering that the capacitor has filtering and voltage stabilization functions, and the electric energy transmitted from the inverter module of the frequency converter to the generator is three-phase AC electric energy, the present application adopts the fourth capacitor C4, the fifth capacitor C5 and the sixth capacitor C6 as the fourth common-mode filter module, the fifth common-mode filter module and the sixth common-mode filter module respectively. In addition, the capacitor has the advantages of good storage performance, long life, small capacitance error, small size, large capacity, good high-frequency characteristics, good frequency stability, low loss, high precision, resistance to high voltage and large current impact, and high reliability.

[0084] As an optional embodiment, the first sub-filter module 5 further includes: a fourth resistor R4;

[0085] A first end of the fourth resistor R4 is connected to the first phase input end of the three-phase filter unit 1, and a second end thereof is connected to the first end of the fourth capacitor C4;

[0086] The second sub-filter module 6 further includes: a fifth resistor R5;

[0087] A first end of the fifth resistor R5 is connected to the second phase input end of the three-phase filter unit 1, and a second end thereof is connected to the first end of the fifth capacitor C5;

[0088] The third sub-filter module 7 further includes: a sixth resistor R6;

[0089] A first end of the sixth resistor R6 is connected to the third phase input end of the three-phase filter unit 1 , and a second end thereof is connected to a first end of the sixth capacitor C6 .

[0090] In the present invention, Figure 3 As shown, considering that the current value corresponding to the electric energy may be high during the process of the inverter transmitting power to the generator, in order to protect the safety of various components in the suppression circuit, this solution adds a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6. The circuit is current-limited by each resistor to protect various components in the suppression circuit. In addition, the resistors have the characteristics of good stability, small negative temperature coefficient, good high-frequency characteristics, small influence by voltage and frequency, small noise electromotive force, stable pulse load, large resistance range, simple manufacturing process, low cost, etc., which are convenient for practical use.

[0091] As an optional embodiment, it further includes: a first switch, a second switch, a third switch, a first differential mode filter module 8, a second differential mode filter module 9, and a third differential mode filter module 10;

[0092] A first end of the first switch is connected to the first phase output end of the three-phase filter unit 1 and the first phase input end of the long-line cable, and a second end of the first switch is connected to the first end of the first differential mode filter module 8;

[0093] A first end of the second switch is connected to the second phase output end of the three-phase filter unit 1 and the second phase input end of the long-line cable, and a second end is connected to the first end of the second differential mode filter module 9;

[0094] A first end of the third switch is connected to the third phase output end of the three-phase filter unit 1 and the third phase input end of the long-line cable, and a second end is connected to the first end of the third differential mode filter module 10;

[0095] The second end of the third differential mode filter module 10 is connected to the second end of the first differential mode filter module 8 and the second end of the second differential mode filter module 9 respectively.

[0096] In the present invention, considering that in the process of the inverter transmitting electric energy to the generator, in addition to the existence of high-frequency common-mode voltage, there will also be high-frequency differential-mode voltage, so this solution additionally provides a first switch, a second switch, a third switch, a first differential-mode filter module 8, a second differential-mode filter module 9, and a third differential-mode filter module 10, wherein the function of the first switch, the second switch, and the third switch is to control the opening of the first differential-mode filter module 8, the second differential-mode filter module 9, and the third differential-mode filter module 10. When the first switch, the second switch, and the third switch are all closed, the first differential-mode filter module 8, the second differential-mode filter module 9, and the third differential-mode filter module 10 filter the high-frequency differential-mode voltage, thereby ensuring the safety of the generator bearings.

[0097] It should be noted that if Figure 4 As shown, the grid-side power unit is the rectifier module of the inverter.

[0098] As an optional embodiment, the method further includes:

[0099] The fourth switch has a first end connected to the second end of the first differential mode filter module 8, the second end of the second differential mode filter module 9 and the second end of the third differential mode filter module 10, and a second end connected to the neutral line of the DC input bus of the inverter module.

[0100] In the present invention, considering that when the first switch, the second switch and the third switch are all closed, the first differential mode filter module 8, the second differential mode filter module 9 and the third differential mode filter module 10 can only filter out the high-frequency differential mode voltage, but in the process of the inverter transmitting electric energy to the generator, there is also a high-frequency common mode voltage, so this solution is further provided with a fourth switch, which is respectively connected to the first differential mode filter module 8, the second differential mode filter module 9, the third differential mode filter module 10 and the neutral line of the DC input bus of the inverter module of the inverter. When the first switch and the second switch are closed, the first differential mode filter module 8, the second differential mode filter module 9 and the third differential mode filter module 10 are closed. When the third switch and the fourth switch are all closed, the first differential mode filter module 8, the second differential mode filter module 9, and the third differential mode filter module 10 are all connected to the neutral line of the DC input bus of the inverter module of the frequency converter, so that the first differential mode filter module 8, the second differential mode filter module 9, and the third differential mode filter module 10 can filter out both high-frequency differential mode voltage and high-frequency common mode voltage, that is, they can simultaneously suppress the common-mode and differential-mode voltages with high du / dt output by the PWM inverter, so that the du / dt of the output voltage is symmetrically suppressed, which is convenient for practical use.

[0101] It should be noted that the first differential mode filter module 8, the second differential mode filter module 9, and the third differential mode filter module 10 are all connected to the neutral line of the DC input bus of the inverter module. Figure 5 shown.

[0102] The present invention further provides a corresponding embodiment of a suppression device, comprising: a housing and the suppression circuit as described above, wherein the suppression circuit is disposed in the housing.

[0103] The suppression device provided in this embodiment corresponds to the above-mentioned suppression circuit, and thus has the same beneficial effects as the above-mentioned suppression circuit. Therefore, for the embodiments of the suppression device part, please refer to the description of the embodiments of the suppression circuit part, which will not be repeated here.

[0104] It should be noted that, in this specification, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0105] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A suppression circuit, characterized in that: include: A three-phase filtering unit, a first common-mode filtering module, a second common-mode filtering module, and a third common-mode filtering module; The three-phase input end of the three-phase filter unit is connected to the three-phase output end of the inverter module of the frequency converter in a one-to-one correspondence, and the three-phase output end is connected to the three-phase input end of the long-line cable in a one-to-one correspondence, and is used to filter out the low-frequency voltage in the three-phase alternating current output by the inverter module, wherein the frequency of the low-frequency voltage is less than a preset low-frequency threshold voltage; The first end of the first common-mode filter module is respectively connected to the first phase output end of the three-phase filter unit and the first phase input end of the long-line cable, and the second end is connected to the ground, and is used to filter out the high-frequency common-mode voltage of the first phase of the three-phase alternating current, wherein the frequency of the high-frequency common-mode voltage is greater than a preset high-frequency threshold voltage; The first end of the second common-mode filter module is respectively connected to the second phase output end of the three-phase filter unit and the second phase input end of the long-line cable, and the second end is connected to the ground, so as to filter out the high-frequency common-mode voltage of the second phase AC in the three-phase AC; The first end of the third common-mode filter module is respectively connected to the third phase output end of the three-phase filter unit and the third phase input end of the long-line cable, and the second end is connected to the ground, so as to filter out the high-frequency common-mode voltage of the third phase of the three-phase alternating current; The three-phase output end of the long-line cable is connected to the generator.

2. The suppression circuit according to claim 1, characterized in that The three-phase filtering unit is a three-phase reactor, the three-phase input end of the three-phase reactor is connected one-to-one with the three-phase output end of the inverter module, and the three-phase output end is connected one-to-one with the three-phase input end of the long-line cable.

3. The suppression circuit according to claim 1, characterized in that The first common-mode filtering module is a first capacitor, a first end of the first capacitor is respectively connected to the first phase output end of the three-phase filtering unit and the first phase input end of the long-line cable, and a second end is connected to the ground; The second common-mode filtering module is a second capacitor, a first end of the second capacitor is respectively connected to the second phase output end of the three-phase filtering unit and the second phase input end of the long-line cable, and a second end is connected to the ground; The third common-mode filtering module is a third capacitor, a first end of which is respectively connected to the third phase output end of the three-phase filtering unit and the third phase input end of the long-line cable, and a second end of which is connected to the ground.

4. The suppression circuit according to claim 3, characterized in that The first common-mode filtering module further includes: a first resistor; The first end of the first resistor is connected to the first phase output end of the three-phase filter unit and the first phase input end of the long-line cable respectively, and the second end is connected to the first end of the first capacitor; The second common-mode filtering module further includes: a second resistor; The first end of the second resistor is connected to the second phase output end of the three-phase filter unit and the second phase input end of the long-line cable respectively, and the second end is connected to the first end of the second capacitor; The third common-mode filtering module further includes: a third resistor; The first end of the third resistor is connected to the third phase output end of the three-phase filtering unit and the third phase input end of the long-line cable respectively, and the second end is connected to the first end of the third capacitor.

5. The suppression circuit according to claim 1, characterized in that Also includes: A first sub-filtering module, a second sub-filtering module, and a third sub-filtering module; The input end of the first sub-filter module is connected to the first phase input end of the three-phase filter unit, and the output end is connected to the first phase output end of the three-phase filter unit, for stabilizing the voltage of the first phase alternating current; The input end of the second sub-filter module is connected to the second phase input end of the three-phase filter unit, and the output end is connected to the second phase output end of the three-phase filter unit, for stabilizing the voltage of the second phase alternating current; The input end of the third sub-filter module is connected to the third phase input end of the three-phase filter unit, and the output end is connected to the third phase output end of the three-phase filter unit, so as to stabilize the voltage of the third phase alternating current.

6. The suppression circuit according to claim 5, characterized in that The first sub-filtering module is a fourth capacitor, a first end of the fourth capacitor is connected to the first phase input end of the three-phase filtering unit, and a second end of the fourth capacitor is connected to the first phase output end of the three-phase filtering unit; The second sub-filtering module is a fifth capacitor, a first end of the fifth capacitor is connected to the second phase input end of the three-phase filtering unit, and a second end of the fifth capacitor is connected to the second phase output end of the three-phase filtering unit; The third sub-filter module is a sixth capacitor, a first end of the sixth capacitor is connected to the third phase input end of the three-phase filter unit, and a second end of the sixth capacitor is connected to the third phase output end of the three-phase filter unit.

7. The suppression circuit according to claim 6, characterized in that The first sub-filter module further includes: a fourth resistor; A first end of the fourth resistor is connected to the first phase input end of the three-phase filtering unit, and a second end is connected to the first end of the fourth capacitor; The second sub-filter module further includes: a fifth resistor; A first end of the fifth resistor is connected to the second phase input end of the three-phase filtering unit, and a second end is connected to the first end of the fifth capacitor; The third sub-filter module further includes: a sixth resistor; The first end of the sixth resistor is connected to the third phase input end of the three-phase filtering unit, and the second end is connected to the first end of the sixth capacitor.

8. The suppression circuit according to any one of claims 1 to 7, characterized in that: Also includes: A first switch, a second switch, a third switch, a first differential mode filter module, a second differential mode filter module, and a third differential mode filter module; A first end of the first switch is connected to a first phase output end of the three-phase filter unit and a first phase input end of the long-line cable, and a second end of the first switch is connected to a first end of the first differential mode filter module; A first end of the second switch is connected to the second phase output end of the three-phase filter unit and the second phase input end of the long-line cable, and a second end is connected to the first end of the second differential mode filter module; The first end of the third switch is connected to the third phase output end of the three-phase filter unit and the third phase input end of the long-line cable, and the second end is connected to the first end of the third differential mode filter module; The second end of the third differential mode filter module is connected to the second end of the first differential mode filter module and the second end of the second differential mode filter module respectively.

9. The suppression circuit according to claim 8, characterized in that Also includes: A fourth switch, wherein a first end of the fourth switch is respectively connected to the second end of the first differential mode filter module, the second end of the second differential mode filter module and the second end of the third differential mode filter module, and a second end of the fourth switch is connected to the neutral line of the DC input bus of the inverter module.

10. A suppression device, characterized in that include: A housing and a suppression circuit as claimed in any one of claims 1 to 9, wherein the suppression circuit is arranged in the housing.

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