Converter AC capacitor switching circuit
By dividing the converter AC capacitor switching and withdrawal process into three stages, with the thyristor and contactor sharing the current bearing, the problem of high current stress and arcing phenomenon during the capacitor switching process is solved, and the reliability and reliability of the circuit are improved. Durability.
Patent Information
- Application Number
- CN202420996029.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-09
- Publication Date
- 2025-01-21
- Estimated Expiration
- 2034-05-09
AI Technical Summary
The existing converter AC capacitor dicing circuit will generate high current stress during the dicing process, resulting in arcing when the contactor dynamic contact is closed or opened, affecting the service life.
A converter AC capacitor switching circuit is designed, which divides the switching and withdrawal of the capacitor into three stages: in the first stage, the thyristor bears the opening moment current, in the second stage, the contactor bears the long-term steady-state current, and in the second stage, the contactor bears the long-term steady-state current. In the third stage, the thyristor bears the current at the turn-off time.
By withstanding the current in stages, the impact of contactor bounce and arcing between contacts during the capacitor switching process on the circuit is reduced, making the entire circuit operation more reliable and durable.
Smart Images
Figure CN222381516U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of wind energy converters, in particular to a converter AC capacitor switching circuit. Background Art
[0002] The AC capacitor switching circuit of the converter in the prior art includes the following aspects. Select a three-phase AC contactor with a large current rating to directly switch the capacitor; or select multiple single-phase AC contactors with a large current rating to directly switch the capacitor; or first use LR to buffer the current stress during AC charging, and then completely switch the capacitor; or first charge the DC bus through the converter soft start circuit, and after charging is completed, the converter grid side module begins to modulate and gradually increase the capacitor voltage, and closes the switching contactor when the capacitor voltage is close to the grid voltage; or add a damping resistor to the capacitor circuit to reduce the current stress of switching during the switching process; or complete the final switching of the capacitor through multiple charging.
[0003] These applications all attempt to reduce the current stress during the switching process of the converter capacitor. In direct switching applications, a contactor with a large current rating must be selected to withstand the impact current and ensure service life; the configuration of damping resistors or current-limiting inductors is also to buffer the current impact during the instantaneous closing of the capacitor, or to quickly reduce the resonant current. The above measures all achieve the switching in and out of the capacitor by closing or opening the moving contacts of the contactor, which will inevitably produce arcing, which will have an adverse effect on the contacts. Utility Model Content
[0004] The technical problem to be solved by the utility model is to propose an inverter AC capacitor switching circuit. The wind energy inverter heating device is connected with the internal and external circulation heat dissipation pipelines of the inverter to form an integral heat dissipation pipeline, which can monitor the temperature and pressure signals in the heat dissipation pipeline in real time. When the temperature in the pipeline and the heating logic are detected to be abnormal, the internal heating element is used to heat the coolant until the temperature meets the operating conditions, thereby ensuring reliable startup and operation of the inverter.
[0005] In order to solve the above technical problems, the utility model provides a converter AC capacitor switching circuit, including an inductor unit, a thyristor unit, a contactor unit, an AC capacitor unit, a detection and control unit, and a thyristor drive unit. The detection and control unit is connected to the three-phase input end of the power grid, and the thyristor unit includes three sets of thyristor assemblies; the three sets of thyristor assemblies include a first set of thyristor assemblies SCR1 and a first drive port thereof, a second set of thyristor assemblies SCR2 and a second drive port thereof, and a third set of thyristor assemblies SCR3 and a third drive port thereof; the first ports of the three sets of thyristor assemblies are connected to the three-phase input end of the power grid through the inductor unit, the second ports of the three sets of thyristor assemblies are connected to the AC capacitor unit, the drive ports of the three sets of thyristor assemblies are connected to the thyristor unit, the detection and control unit is connected to the thyristor unit, and the contactor unit is connected between the three-phase input end of the power grid and the second ports of the three sets of thyristor assemblies.
[0006] Preferably, the first set of thyristor components SCR1 is composed of two thyristors connected in anti-parallel; the second set of thyristor components SCR2 is composed of two thyristors connected in anti-parallel; and the third set of thyristor components SCR3 is composed of two thyristors connected in anti-parallel.
[0007] Preferably, the inductor unit includes at least three air-core inductors, and the three air-core inductors include a first air-core inductor L1, a second air-core inductor L2, and a third air-core inductor L3; the first port of the first air-core inductor L1 is connected to the U-phase port of the power grid; the first port of the second air-core inductor L2 is connected to the V-phase port of the power grid; the first port of the third air-core inductor L3 is connected to the W-phase port of the power grid; the first port of the first set of thyristor components SCR1 is connected to the second port of the first air-core inductor L1; the first port of the second set of thyristor components SCR2 is connected to the second port of the second air-core inductor L2; the first port of the third set of thyristor components SCR3 is connected to the second port of the third air-core inductor L3.
[0008] Preferably, the contactor unit comprises at least one three-phase contactor KM3;
[0009] The first port of the three-phase contactor KM3 is connected to the U-phase port of the power grid; the second port of the three-phase contactor KM3 is connected to the V-phase port of the power grid; the third port of the three-phase contactor KM3 is connected to the W-phase port of the power grid; the fourth port of the three-phase contactor KM3 is connected to the second port of the first set of thyristor components SCR1; the fifth port of the three-phase contactor KM3 is connected to the second port of the second set of thyristor components SCR2; the sixth port of the three-phase contactor KM3 is connected to the second port of the third set of thyristor components SCR3.
[0010] Preferably, the AC capacitor unit includes three AC capacitors; the three AC capacitors include a first capacitor C1, a second capacitor C2 and a third capacitor C3; the first port of the first capacitor C1 is connected to the second port of the first set of thyristor components SCR1; the first port of the second capacitor C2 is connected to the second port of the second set of thyristor components SCR2; the first port of the third capacitor C3 is connected to the second port of the third set of thyristor components SCR3; the second port of the first capacitor C1 is connected to the second port of the second capacitor C2; the second port of the second capacitor C2 is connected to the second port of the third capacitor C3.
[0011] Preferably, the detection and control unit includes a first signal port, a second signal port, a third signal port, and a fourth signal port;
[0012] The first signal port is connected to a U-phase port of a power grid, the second signal port is connected to a V-phase port of a power grid, and the third signal port is connected to a W-phase port of a power grid.
[0013] Preferably, the thyristor driving unit comprises a first driving port, a second driving port, a third driving port, and a fourth driving port;
[0014] The first drive port is connected to the first drive port of the first set of thyristor components SCR1, the second drive port is connected to the second drive port of the second set of thyristor components SCR2, the third drive port is connected to the third drive port of the third set of thyristor components SCR3, and the fourth drive port is connected to the fourth signal port of the detection and control unit.
[0015] After adopting the above circuit, the converter AC capacitor switching circuit includes an inductor unit, a thyristor unit, a contactor unit, an AC capacitor unit, a detection and control unit, and a thyristor drive unit. The detection and control unit is connected to the three-phase input end of the power grid. The thyristor unit includes three sets of thyristor components; the three sets of thyristor components include a first set of thyristor components SCR1 and a first drive port thereof, a second set of thyristor components SCR2 and a second drive port thereof, and a third set of thyristor components SCR3 and a third drive port thereof; the first ports of the three sets of thyristor components are connected to the three-phase input end of the power grid through the inductor unit, and the The second port is connected to the AC capacitor unit, the driving ports of the three sets of thyristor assemblies are connected to the thyristor unit, the detection and control unit is connected to the thyristor unit, and the contactor unit is connected between the three-phase input end of the power grid and the second ports of the three sets of thyristor assemblies; the converter AC capacitor switching circuit divides the switching and exiting of the capacitor into three stages, the first stage is borne by the thyristor at the turn-on moment current, the second stage is borne by the contactor at the long-term steady-state current, and the third stage is borne by the thyristor at the turn-off moment current, which can reduce the impact of contactor bounce and arcing between contacts on the circuit during the capacitor switching process, so that the entire circuit can operate reliably and durable. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 The utility model is an overall circuit diagram of an AC capacitor switching circuit of a converter.
[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0019] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.
[0020] Embodiment 1
[0021] See also Figure 1 , Figure 1 The utility model is an overall circuit diagram of an AC capacitor switching circuit of a converter.
[0022] The present embodiment discloses a converter AC capacitor switching circuit, comprising an inductor unit 30, a thyristor unit 40, a contactor unit 50, an AC capacitor unit 60, a detection and control unit 10, and a thyristor drive unit 20. The detection and control unit 10 is connected to the three-phase input end of the power grid. The thyristor unit 40 includes three sets of thyristor assemblies; the three sets of thyristor assemblies include a first set of thyristor assemblies SCR1 and a first drive port thereof, a second set of thyristor assemblies SCR2 and a second drive port thereof, and a third set of thyristor assemblies SCR3 and a third drive port thereof; the first ports of the three sets of thyristor assemblies are connected to the three-phase input end of the power grid through the inductor unit 30, the second ports of the three sets of thyristor assemblies are connected to the AC capacitor unit 60, the drive ports of the three sets of thyristor assemblies are connected to the thyristor unit 40, the detection and control unit 10 is connected to the thyristor unit 40, and the contactor unit 50 is connected between the three-phase input end of the power grid and the second ports of the three sets of thyristor assemblies.
[0023] Embodiment 2
[0024] This embodiment is based on the first embodiment. In this embodiment, the first set of thyristor components SCR1 is composed of two thyristors connected in anti-parallel; the second set of thyristor components SCR2 is composed of two thyristors connected in anti-parallel; and the third set of thyristor components SCR3 is composed of two thyristors connected in anti-parallel.
[0025] Embodiment 3
[0026] This embodiment is based on the first embodiment. In this embodiment, the inductor unit 30 includes at least three air-core inductors, and the three air-core inductors include a first air-core inductor L1, a second air-core inductor L2, and a third air-core inductor L3; the first port of the first air-core inductor L1 is connected to the U-phase port of the power grid; the first port of the second air-core inductor L2 is connected to the V-phase port of the power grid; the first port of the third air-core inductor L3 is connected to the W-phase port of the power grid; the first port of the first set of thyristor components SCR1 is connected to the second port of the first air-core inductor L1; the first port of the second set of thyristor components SCR2 is connected to the second port of the second air-core inductor L2; the first port of the third set of thyristor components SCR3 is connected to the second port of the third air-core inductor L3.
[0027] Embodiment 4
[0028] This embodiment is based on the first embodiment. In this embodiment, the contactor unit 50 includes at least one three-phase contactor KM3;
[0029] The first port of the three-phase contactor KM3 is connected to the U-phase port of the power grid; the second port of the three-phase contactor KM3 is connected to the V-phase port of the power grid; the third port of the three-phase contactor KM3 is connected to the W-phase port of the power grid; the fourth port of the three-phase contactor KM3 is connected to the second port of the first set of thyristor components SCR1; the fifth port of the three-phase contactor KM3 is connected to the second port of the second set of thyristor components SCR2; the sixth port of the three-phase contactor KM3 is connected to the second port of the third set of thyristor components SCR3.
[0030] In this embodiment, the AC capacitor unit 60 includes three AC capacitors; the three AC capacitors include a first capacitor C1, a second capacitor C2 and a third capacitor C3; the first port of the first capacitor C1 is connected to the second port of the first set of thyristor components SCR1; the first port of the second capacitor C2 is connected to the second port of the second set of thyristor components SCR2; the first port of the third capacitor C3 is connected to the second port of the third set of thyristor components SCR3; the second port of the first capacitor C1 is connected to the second port of the second capacitor C2; the second port of the second capacitor C2 is connected to the second port of the third capacitor C3.
[0031] Embodiment 5
[0032] This embodiment is based on the first embodiment. In this embodiment, the detection and control unit 10 includes a first signal port, a second signal port, a third signal port, and a fourth signal port;
[0033] The first signal port is connected to a U-phase port of a power grid, the second signal port is connected to a V-phase port of a power grid, and the third signal port is connected to a W-phase port of a power grid.
[0034] The thyristor driving unit 20 includes a first driving port, a second driving port, a third driving port, and a fourth driving port;
[0035] The first drive port is connected to the first drive port of the first set of thyristor components SCR1, the second drive port is connected to the second drive port of the second set of thyristor components SCR2, the third drive port is connected to the third drive port of the third set of thyristor components SCR3, and the fourth drive port is connected to the fourth signal port of the detection and control unit.
[0036] The converter AC capacitor switching circuit divides the switching and exiting of the capacitor into three stages. In the first stage, the thyristor bears the current at the turn-on moment, in the second stage, the contactor bears the long-term steady-state current, and in the third stage, the thyristor bears the current at the turn-off moment. This can reduce the impact of contactor bounce and arcing between contacts during the capacitor switching process on the circuit, making the entire circuit reliable and durable.
[0037] The preferred embodiments of the present application are described above with reference to the accompanying drawings, but the scope of the present application is not limited thereby. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present application shall be within the scope of the present application.
Claims
1. A converter AC capacitor switching circuit, characterized in that: It includes an inductor unit, a thyristor unit, a contactor unit, an AC capacitor unit, a detection and control unit, and a thyristor drive unit. The detection and control unit is connected to the three-phase input end of the power grid. The thyristor unit includes three sets of thyristor assemblies; the three sets of thyristor assemblies include a first set of thyristor assemblies SCR1 and a first drive port thereof, a second set of thyristor assemblies SCR2 and a second drive port thereof, and a third set of thyristor assemblies SCR3 and a third drive port thereof; the first ports of the three sets of thyristor assemblies are connected to the three-phase input end of the power grid through the inductor unit, the second ports of the three sets of thyristor assemblies are connected to the AC capacitor unit, the drive ports of the three sets of thyristor assemblies are connected to the thyristor unit, the detection and control unit is connected to the thyristor unit, and the contactor unit is connected between the three-phase input end of the power grid and the second ports of the three sets of thyristor assemblies.
2. The converter AC capacitor switching circuit according to claim 1, characterized in that: The first set of thyristor components SCR1 is composed of two thyristors connected in anti-parallel; the second set of thyristor components SCR2 is composed of two thyristors connected in anti-parallel; and the third set of thyristor components SCR3 is composed of two thyristors connected in anti-parallel.
3. The converter AC capacitor switching circuit according to claim 1, characterized in that: The inductor unit includes at least three air-core inductors, and the three air-core inductors include a first air-core inductor L1, a second air-core inductor L2, and a third air-core inductor L3; the first port of the first air-core inductor L1 is connected to the U-phase port of the power grid; the first port of the second air-core inductor L2 is connected to the V-phase port of the power grid; the first port of the third air-core inductor L3 is connected to the W-phase port of the power grid; the first port of the first set of thyristor components SCR1 is connected to the second port of the first air-core inductor L1; the first port of the second set of thyristor components SCR2 is connected to the second port of the second air-core inductor L2; the first port of the third set of thyristor components SCR3 is connected to the second port of the third air-core inductor L3.
4. The converter AC capacitor switching circuit according to claim 1, characterized in that: The contactor unit includes at least one three-phase contactor KM3; The first port of the three-phase contactor KM3 is connected to the U-phase port of the power grid; the second port of the three-phase contactor KM3 is connected to the V-phase port of the power grid; the third port of the three-phase contactor KM3 is connected to the W-phase port of the power grid; the fourth port of the three-phase contactor KM3 is connected to the second port of the first set of thyristor components SCR1; the fifth port of the three-phase contactor KM3 is connected to the second port of the second set of thyristor components SCR2; the sixth port of the three-phase contactor KM3 is connected to the second port of the third set of thyristor components SCR3.
5. The converter AC capacitor switching circuit according to claim 1, characterized in that: The AC capacitor unit includes three AC capacitors; the three AC capacitors include a first capacitor C1, a second capacitor C2 and a third capacitor C3; the first port of the first capacitor C1 is connected to the second port of the first set of thyristor components SCR1; the first port of the second capacitor C2 is connected to the second port of the second set of thyristor components SCR2; the first port of the third capacitor C3 is connected to the second port of the third set of thyristor components SCR3; the second port of the first capacitor C1 is connected to the second port of the second capacitor C2; the second port of the second capacitor C2 is connected to the second port of the third capacitor C3.
6. The converter AC capacitor switching circuit according to claim 1, characterized in that: The detection and control unit includes a first signal port, a second signal port, a third signal port, and a fourth signal port; The first signal port is connected to a U-phase port of a power grid, the second signal port is connected to a V-phase port of a power grid, and the third signal port is connected to a W-phase port of a power grid.
7. The converter AC capacitor switching circuit according to claim 6, characterized in that: The thyristor driving unit comprises a first driving port, a second driving port, a third driving port and a fourth driving port; The first drive port is connected to the first drive port of the first set of thyristor components SCR1, the second drive port is connected to the second drive port of the second set of thyristor components SCR2, the third drive port is connected to the third drive port of the third set of thyristor components SCR3, and the fourth drive port is connected to the fourth signal port of the detection and control unit.