Control system for automatically adjusting current of alternating-current arc heater

Abstract

The invention relates to a control system for automatically adjusting current of an alternating current arc heater, and belongs to the technical field of power electronic conversion. The PLC control module and the circuit breaker trigger control unit are mainly used for controlling the on-off states of different taps of the choke reactor in a circuit by the thyristor solid-state switch, so that the working current of the alternating-current arc heater is automatically adjusted. The industrial network technology and the PLC technology are adopted, automatic adjustment of the current of the alternating-current arc heater is achieved, manual tap replacement is avoided, and the working efficiency is improved; and the advanced thyristor solid-state switch technology is applied, so that the reliability and the safety of the equipment are improved, and the failure rate of the equipment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic current conversion, in particular to a control system for automatically adjusting 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, which causes intense friction with the surface of the spacecraft and generates high temperatures. This high temperature will have an adverse effect on the mechanical structure of the spacecraft. Therefore, the heat protection materials of its heat protection system need to be subjected to aerodynamic thermal tests on the ground to assess their heat protection performance.

[0003] Aerodynamic thermal tests are generally carried out in arc heater jets or arc wind tunnels. AC arc heaters are one of the devices that generate plasma arcs and are used to simulate high-pressure, medium-low enthalpy operating environments. The heater is powered directly by the industrial power grid, and the A, B, and C phase electrodes of the arc heater are arranged in a "star" in space and connected in the middle by a mixing chamber to form a three-phase symmetrical "star" arc load heater.

[0004] During the entire orbital operation, the spacecraft experienced different aerodynamic heating states. In order to reproduce the actual test state in the ground simulation test, it is necessary to change the output power of the heater by adjusting the electrical parameters of the arc heater, thereby changing the state of the high-temperature airflow to simulate the aerodynamic thermal test state of the aircraft. In the previous AC arc heater, since the reactor in the circuit system had a multi-stage fixed tap, it was necessary to manually change the reactor tap after the test was stopped to change the reactor resistance value and thus change 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 adjusting the current of an AC arc heater. The present invention is based on power electronics technology and a new generation of AC switch technology with thyristor devices as the core, which can be quickly switched and the switching time is precisely controllable, thereby realizing automatic adjustment of the current of 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 switch cabinet is a vacuum central cabinet, and its upstream is connected to the power supply end. The transformer is a step-up transformer, and its primary side is connected to the switch cabinet, and its secondary side is connected to the solid-state switch. The solid-state switch uses thyristor as the core device, and the switch is a multi-stage switch control type, which corresponds to the taps of various gears of the choke reactor respectively. 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 working current and voltage signals on the line.

[0009] The trigger control unit receives the running gear 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 voltage output 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 graded 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, which is connected to the PLC control module via the Modbus communication protocol, and 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. The functions include downloading the experimental program 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 working 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 working position of the choke reactor to control the inductance of the reactor in operation and realize automatic control of the current. The automatic adjustment of the current of the AC arc heater is realized, avoiding manual replacement of the tap and improving the work efficiency: by inputting different experimental programs, setting the working time of each position, adjusting the tap of the reactor in operation by turning on and off the thyristor solid-state switch, and changing the inductance of the reactor to realize automatic adjustment of the current.

[0020] Solid-state switching technology is used, with thyristors as the core devices. Since the current of thyristor devices naturally crosses zero and turns off, there will be no transient overvoltage caused by inductive energy storage in the load or line when turning off. At the same time, since there are no contacts and movable mechanical structures in the main circuit of the switch, there are no problems such as arcing, contact wear and welding. The application of thyristor solid-state switching technology, which relies on power electronic semiconductor technology, has no contacts and movable mechanical structures in its main circuit, avoiding problems such as arcing, contact wear and welding.

[0021] This system uses the Profinet network interface to interlock 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 is further described in detail below in conjunction with specific embodiments.

[0024] like Figure 1 As shown, the present invention proposes a control system for automatically adjusting 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 for the AC arc heater system.

[0026] Transformer 2 is a step-up transformer, the primary side of which is connected to switch cabinet 1, and the secondary side is connected to solid-state switch 3. The function of transformer 2 is to achieve voltage conversion, converting the 380V input voltage into 1500V or higher voltage output for use by the AC arc heater.

[0027] The solid-state switch 3 uses a thyristor as a core device, and the switch is a multi-stage switch control type, corresponding to the taps of various gears of the choke reactor 4. Figure 1 In the embodiment shown, a 4-level switch mode is adopted, which corresponds to the taps of the 4 gears 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 and off of each level of the solid-state switch 3 is controlled, thereby controlling the inductance of the choke reactor 4 put into operation, and realizing automatic adjustment of the current. When the gear n is larger, we can achieve more gears of current output within a certain 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 are 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 through the Modbus communication protocol. It receives and sends the switch pulse signal of the corresponding gear thyristor to the solid-state switch 3 according to the running gear signal, and at the same time 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 can be 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 reactor 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 the experimental program and collecting and monitoring the operating data and status of the system.

[0033] Although the present invention is disclosed as above in the form of a preferred embodiment, 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: Switch cabinet (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 device, 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 position 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 an output voltage of 1500V or higher 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 switch 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 graded 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 position 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. The 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 procedure 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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