A control system for automatically adjusting current of AC arc heater

Abstract

The present invention relates to a control system for automatically adjusting the current of an AC arc heater, belonging to the technical field of power electronic current conversion. A PLC control module and a circuit breaker trigger control unit are mainly used to implement thyristor solid-state switches to control the on-off state of different taps of a choke reactor in the circuit, thereby achieving automatic adjustment of the operating current of the AC arc heater. The present invention adopts industrial network technology and PLC technology to achieve automatic adjustment of the current of the AC arc heater, avoiding manual replacement of taps and improving work efficiency. The application of advanced thyristor solid-state switch technology improves the reliability and safety of the equipment and reduces the failure rate of the equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic current conversion, in particular to a control system for automatically regulating current of an AC arc heater. Background Art

[0002] When a spacecraft re-enters the atmosphere, the surrounding air is strongly compressed by the bow shock wave, generating intense friction with the vehicle's surface and generating high temperatures. This high temperature can adversely affect the vehicle's mechanical structure. Therefore, the thermal protection materials of its thermal protection system require ground-based aerodynamic thermal testing to assess their thermal performance.

[0003] Aerothermal testing is typically conducted in an arc heater jet or arc wind tunnel. An AC arc heater is a device that generates a plasma arc and is used to simulate high-pressure, medium-to-low enthalpy operating environments. The heater is powered directly by the industrial grid. The A, B, and C phases of the arc heater are arranged in a "star" pattern in space and connected by a mixing chamber, creating a three-phase symmetrical "star" arc load.

[0004] During the entire orbital operation, the spacecraft experiences different aerodynamic heating states. In order to reproduce the actual test conditions in ground simulation tests, it is necessary to change the output power of the arc heater by adjusting the electrical parameters of the arc heater, thereby changing the state of the high-temperature airflow to simulate the aerodynamic heating test state of the aircraft. Previous AC arc heaters had multi-stage fixed taps in the circuit system of the reactor. This required manual changes to the reactor taps after the test was stopped to change the reactor resistance value and thus the current. This method could not meet the requirements of changing the electrical state parameters in real time during the test to change the test state. Summary of the Invention

[0005] The present invention provides a control system for automatically regulating the current of an AC arc heater. Based on power electronics technology and a new generation of AC switching technology with thyristor devices at its core, the system enables rapid switching and precise control of the switching timing, thus achieving automatic current regulation in the AC arc heater.

[0006] In a first aspect, a control system for automatically adjusting current of an AC arc heater is provided, characterized in that it includes:

[0007] Switchgear, transformers, solid-state switches, choke reactors, measuring devices, three-phase AC arc heaters, trigger control units, PLC control modules;

[0008] The switchgear is a vacuum-mounted cabinet, connected upstream to the power supply. The transformer is a step-up transformer, with its primary side connected to the switchgear and its secondary side connected to a solid-state switch. The solid-state switch uses a thyristor as its core component and adopts a multi-stage switch control type, corresponding to the taps of the various gears of the choke reactor. The other pole of the solid-state switch is connected to the transformer. The measuring device includes a current transformer and a voltage transformer, which are connected to the three-phase line to collect the operating current and voltage signals on the line.

[0009] The trigger control unit receives the operating gear position signal from the PLC control module, sends the corresponding gear thyristor switch pulse signal to the solid-state switch, controls the on and off of each level of the solid-state switch; and transmits the three-phase voltage and current on the line collected by the measuring device to the PLC control module;

[0010] The PLC control module is used to send an operating gear signal to the trigger control unit according to the voltage and current, thereby controlling the inductance of the reactor when it is put into operation and realizing automatic regulation of the current.

[0011] In combination with the first aspect, in certain implementations of the first aspect, the transformer converts the 380V input voltage into a 1500V or higher output voltage for use by the AC arc heater.

[0012] In combination with the first aspect, in certain implementations of the first aspect, the solid-state switch adopts an n-level switching mode corresponding to the taps of n gears of the choke inductor, and the n gears realize n resistance values ​​of the inductor, thereby realizing n different current outputs in the circuit, n≥3.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the choke reactor is a hollow hierarchical structure, which is used to achieve current limiting and current regulation of the AC arc heater.

[0014] In combination with the first aspect, in certain implementations of the first aspect, the trigger control unit is equipped with an RS485 interface and is connected to the PLC control module via the Modbus communication protocol. The PLC control module sends the running gear signal in the program to the trigger control unit via the RS485 interface.

[0015] In combination with the first aspect, in certain implementations of the first aspect, the control system also includes a host computer, which is an industrial computer with monitoring and data acquisition software installed inside. Its functions include downloading experimental programs to the PLC control module and collecting and monitoring the operating data and status of the system.

[0016] In combination with the first aspect, in certain implementations of the first aspect, the experimental program sets the operating time of each gear of the choke reactor, and adjusts the tap at which the reactor is put into operation by turning on and off the solid-state switch.

[0017] In combination with the first aspect, in certain implementations of the first aspect, the host computer is connected to the PLC control module via a Profinet network.

[0018] Compared with the prior art, the solution provided by the present invention includes at least the following beneficial technical effects:

[0019] The multi-stage solid-state switch is used to control the operating position of the choke reactor to control the inductance of the reactor when it is put into operation, realizing automatic control of the current. The automatic adjustment of the current of the AC arc heater is realized, eliminating the need for manual replacement of the tap and improving work efficiency: by inputting different experimental programs, setting the working time of each gear, adjusting the tap of the reactor when it is put into operation by turning the thyristor solid-state switch on and off, and changing the inductance of the reactor to realize automatic adjustment of the current.

[0020] Solid-state switching technology is employed, with thyristors as the core components. Since thyristor devices naturally shut down at zero current, transient overvoltages caused by inductive energy storage in the load or circuits are eliminated during shutdown. Furthermore, since the switch's main circuit lacks contacts or moving mechanical structures, arcing, contact wear, and welding are eliminated. The application of thyristor solid-state switching technology, which relies on power electronics semiconductor technology, eliminates the need for contacts or moving mechanical structures in the main circuit, thus avoiding arcing, contact wear, and welding.

[0021] This system uses the Profinet network interface to perform interlocking control with the water and gas of the process equipment to achieve automated control of the pneumatic thermal experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a schematic diagram of a control system for automatically adjusting current of an AC arc heater. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail below with reference to specific embodiments.

[0024] like Figure 1 As shown, the present invention proposes a control system for automatically adjusting the current of an AC arc heater, which mainly includes: a switch cabinet 1, a transformer 2, a solid-state switch 3, a choke reactor 4, a measuring device 5, a three-phase AC arc heater 6, a trigger control unit 7, a PLC control module 8 and a host computer 9.

[0025] The switch cabinet 1 is a vacuum central cabinet, and its upstream is connected to the AC 380V power supply terminal to realize power supply and protection of the AC arc heater system.

[0026] Transformer 2 is a step-up transformer, with its primary side connected to switchgear 1 and its secondary side connected to solid-state switch 3. Transformer 2 converts the 380V input voltage to 1500V or higher output voltage for use in the AC arc heater.

[0027] The solid-state switch 3 uses a thyristor as its core component and is a multi-stage switch control type, corresponding to the taps of the various gears of the choke reactor 4. Figure 1 The illustrated embodiment employs a four-level switching mode, corresponding to the four tap positions of the choke reactor 4. The other pole of the solid-state switch 3 is connected to the transformer 2. By triggering the control unit 7, the on / off switching of each level of the solid-state switch 3 is controlled, thereby controlling the inductance of the choke reactor 4 when in operation, achieving automatic current regulation. The larger the level n, the more current output levels can be achieved within a given adjustable current range.

[0028] The choke reactor 4 is a hollow graded structure, which realizes the current limiting and current regulation of the AC arc heater.

[0029] The measuring device 5 includes a current transformer and a voltage transformer, which are connected to the three-phase line and used to collect the working current and voltage signals on the line for display and protection.

[0030] The trigger control unit 7 is equipped with an RS485 interface and is connected to the PLC control module 8 via the Modbus communication protocol. It receives and, based on the operating gear position signal, sends the switching pulse signal of the corresponding gear thyristor to the solid-state switch 3. At the same time, it transmits the three-phase voltage and current on the line collected by the measuring device 5 to the PLC control module 8 for display and protection.

[0031] The PLC control module 8 can communicate with the host computer 9 through the Profinet interface to exchange data. Different experimental programs can be downloaded to the PLC control module 8 through the host computer 9, and the signal of the running gear in the program is sent to the trigger control unit 7 through the RS485 interface to control the on and off of the solid-state switch of each gear, thereby controlling the inductance of the inductor put into operation and realizing automatic adjustment of the current.

[0032] The host computer 9 is an industrial computer with monitoring and data acquisition software installed inside. It is connected to the PLC control module 8 through the Profinet network. Its functions mainly include downloading experimental programs and collecting and monitoring the operating data and status of the system.

[0033] Although the present invention is disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A control system for automatically adjusting the current of an AC arc heater, characterized in that: include: Switchgear (1), transformer (2), solid-state switch (3), choke reactor (4), measuring device (5), three-phase AC arc heater (6), trigger control unit (7), PLC control module (8); The switch cabinet (1) is a vacuum central cabinet, the upstream of which is connected to the power supply end; the transformer (2) is a step-up transformer, the primary side of which is connected to the switch cabinet (1), and the secondary side of which is connected to the solid-state switch (3); the solid-state switch (3) uses a thyristor as a core component, and the switch is a multi-stage switch control type, which respectively corresponds to the taps of various gears of the choke reactor (4); the other pole of the solid-state switch (3) is connected to the transformer (2); the measuring device (5) includes a current transformer and a voltage transformer, which are connected to the three-phase line and are used to collect the working current and voltage signals on the line; The trigger control unit (7) receives the operating gear position signal from the PLC control module (8), sends the corresponding gear position thyristor switch pulse signal to the solid-state switch (3), controls the on and off of each level of the solid-state switch (3); and transmits the three-phase voltage and current on the line collected by the measuring device (5) to the PLC control module (8); The PLC control module (8) is used to send an operating gear signal to the trigger control unit (7) according to the voltage and current, thereby controlling the inductance of the reactor when it is put into operation and realizing automatic regulation of the current.

2. The control system according to claim 1, characterized in that: The transformer (2) converts the 380V input voltage into 1500V or higher output voltage for use by the AC arc heater.

3. The control system according to claim 1, characterized in that: The solid-state switch (3) adopts an n-level switching mode corresponding to the taps of n gears of the choke reactor (4), and the n gears realize n resistance values ​​of the reactor, thereby realizing n different current outputs in the circuit, n≥3.

4. The control system according to claim 1, characterized in that: The choke reactor (4) is a hollow hierarchical structure and is used to achieve current limiting and current regulation of the AC arc heater.

5. The control system according to claim 1, characterized in that: The trigger control unit (7) is equipped with an RS485 interface and is connected to the PLC control module (8) via the Modbus communication protocol. The PLC control module (8) sends the running gear signal in the program to the trigger control unit (7) via the RS485 interface.

6. The control system according to claim 1, characterized in that: The control system also includes a host computer (9), which is an industrial computer with monitoring and data acquisition software installed inside. Its functions include downloading the experimental program to the PLC control module (8) and collecting and monitoring the operating data and status of the system.

7. The control system according to claim 6, characterized in that: The experimental program sets the working time of each gear of the choke reactor (4), and adjusts the tap of the reactor put into operation by turning on and off the solid-state switch (3).

8. The control system according to claim 1, characterized in that: The host computer (9) is connected to the PLC control module (8) via a Profinet network.

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