Rectifying power supply device for vacuum arc furnace and control method

Abstract

The invention relates to a rectification power supply device for a vacuum arc furnace and a control method. The device comprises a low-voltage large-current rectification assembly and a front adjustable boost rectification assembly which are output in parallel, and an intelligent controller assembly. The low-voltage large-current rectification assembly comprises a multi-winding transformer, at least two three-phase five-column type double-reverse-star-shaped rectification transformers, a silicon controlled rectifier voltage regulation circuit and a diode rectification circuit. The front adjustable boost rectification assembly comprises a single-phase transformer and a full-bridge rectification circuit composed of a silicon controlled rectifier and a diode. The intelligent controller assembly controls the front adjustable boost rectification assembly to output high open-circuit voltage to ignite the arc and controls the output of the low-voltage large-current rectification assembly to maintain arc combustion in different stages according to the operation state signal. High-capacity low-voltage large-current rectification and small-capacity adjustable boosting rectification are output in parallel, the requirements of the vacuum arc furnace for high no-load voltage and large working current can be met at the same time, and the situation that the load rate of a rectifier transformer is low is avoided.

Description

Technical Field

[0001] This invention relates to the field of vacuum electric arc furnace technology; specifically, this invention relates to a rectifier power supply device and control method for a vacuum electric arc furnace. Background Technology

[0002] Vacuum arc furnaces are widely used in the smelting of special high-temperature alloy steels. Their smelting power supply typically uses low-voltage, high-current, high-pulse DC power, with voltages generally ranging from 10 to 50VDC and currents in the tens of kA range, using pulses of 12, 18, or 24. In the initial stage of the smelting process, a relatively high open-circuit voltage (around 80V) and a small arc current output are required to facilitate arc ignition. Once the arc is ignited, it must be immediately controlled to enter a constant short-arc state, requiring an arc voltage of generally 25V to 40VDC and an arc current exceeding several kA. To simultaneously meet the requirements of a high open-circuit voltage and a large operating current, the rectifier transformer's load rate will inevitably be relatively low. Summary of the Invention

[0003] In view of this, the present invention provides a rectifier power supply device and control method for a vacuum electric arc furnace, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0004] To achieve the aforementioned objective, a first aspect of the present invention provides a rectifier power supply device for a vacuum electric arc furnace, comprising:

[0005] A low-voltage, high-current rectifier assembly includes a multi-winding transformer, at least two three-phase five-limb double-reverse star rectifier transformers, a thyristor voltage regulation circuit, and a diode rectifier circuit. The primary side of the multi-winding transformer is connected to an AC power supply, and the secondary side includes multiple windings. The primary side of each three-phase rectifier transformer is connected to the corresponding secondary winding of the multi-winding transformer through a corresponding thyristor voltage regulation circuit. The secondary side of each three-phase rectifier transformer is connected to a corresponding diode rectifier circuit.

[0006] The pre-adjustable boost rectifier assembly includes a single-phase transformer and a full-bridge rectifier circuit. The primary side of the single-phase transformer is connected to an AC power supply, and the secondary side is connected to the full-bridge rectifier circuit. The full-bridge rectifier circuit includes a thyristor and a diode. The pre-adjustable boost rectifier assembly is connected in parallel with the low-voltage high-current rectifier assembly to output DC power.

[0007] The intelligent controller component is used to receive the operating status signals of the low-voltage high-current rectifier component and the pre-adjustable boost rectifier component, and control each thyristor according to the received signals. When the vacuum arc furnace has not ignited the arc, the pre-adjustable boost rectifier component is controlled to output a pre-open circuit voltage higher than the smelting working voltage for igniting the arc. After the arc has been established, the low-voltage high-current rectifier component maintains the arc combustion, and performs protection operations when an abnormality is detected.

[0008] In the rectifier power supply device described above, optionally, the primary winding of the multi-winding transformer adopts a delta connection, and the secondary side includes two sets of windings, one set adopts a star connection and the other set adopts a delta connection.

[0009] The number of three-phase five-limb double-reverse star rectifier transformers is two. The secondary side of the two three-phase rectifier transformers is connected to diode rectifier circuits respectively, forming a double-reverse star rectifier structure with a balancing reactor, and forming a 12-pulse rectified output.

[0010] Optionally, in the rectifier power supply device described above, the rectifier power supply device further includes a filter reactor connected to the DC output side and a shunt for current sampling.

[0011] Furthermore, the thyristor in the thyristor voltage regulation circuit, the diode in the diode rectifier circuit, the filter reactor, and the shunt are all water-cooled.

[0012] In the rectifier power supply device described above, optionally, the low-voltage high-current rectifier component is connected to the DC output terminal through a hollow rectangular water-cooled copper busbar.

[0013] The cooling medium for the water-cooled components in the rectifier power supply device is pure water.

[0014] In the rectifier power supply device described above, optionally, the signals received by the intelligent controller component include the synchronous voltage signal of the AC power supply, the rectified output voltage divider signal, and the current sampling signal sampled using a shunt.

[0015] In the aforementioned rectifier power supply device, optionally, the signals received by the intelligent controller component also include temperature detection signals from the thermistors of the transformer and reactor, and temperature detection signals from the thermistors of the thyristor, and perform overheat protection operation when an abnormal temperature is detected.

[0016] In the rectifier power supply device described above, optionally, the intelligent controller component adopts an integrated intelligent controller that supports ProfiNet communication.

[0017] To achieve the aforementioned objective, a second aspect of the present invention provides a control method for a rectifier power supply of a vacuum electric arc furnace, wherein the control method is applied to a rectifier power supply device as described in any one of the preceding first aspects, and the control method includes:

[0018] Before the electric arc furnace is ignited, the pre-adjustable boost rectifier assembly is controlled to output a pre-open circuit voltage higher than the smelting working voltage to ignite the electric arc.

[0019] After an electric arc is detected to have been established, the thyristor in the pre-adjustable boost rectifier is turned off. At the same time, the low-voltage high-current rectifier that has been following the voltage output begins to adjust automatically to stably maintain the burning of the electric arc.

[0020] If the arc is detected to be extinguished during the furnace process, the control will activate the pre-adjustable boost rectifier component to reignite the arc.

[0021] In the control method described above, optionally, an arc is determined to have been established by detecting whether the DC output current of the rectifier power supply device reaches a preset current threshold. When the DC output current reaches the current threshold, the thyristor in the pre-adjustable boost rectifier assembly is turned off.

[0022] In the control method described above, optionally, during the furnace process, the arc is extinguished by detecting an abnormal drop in the DC output current of the rectifier power supply device, and after the arc is extinguished, the pre-adjustable boost rectifier assembly is automatically activated to reignite the arc.

[0023] The rectifier power supply device for vacuum electric arc furnace of the present invention connects a large-capacity low-voltage high-current rectifier and a small-capacity adjustable boost rectifier in parallel for output, which can simultaneously meet the requirements of vacuum electric arc furnace for high open-circuit voltage and large operating current, and avoid low load rate of rectifier transformer.

[0024] The present invention further provides a control method for the rectifier power supply device of the vacuum electric arc furnace of the present invention, and therefore the control method also has the above-mentioned advantages. Attached Figure Description

[0025] The disclosure of this invention will become more apparent from the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings:

[0026] Figure 1 This is a schematic diagram of one embodiment of the rectifier power supply device for a vacuum electric arc furnace according to the present invention;

[0027] Figure 2 This is a schematic diagram of a low-voltage, high-current rectifier assembly according to an embodiment of the rectifier power supply device for a vacuum electric arc furnace of the present invention.

[0028] Figure 3 This is a schematic diagram of a pre-adjustable boost rectifier assembly, representing one embodiment of the rectifier power supply device for a vacuum electric arc furnace according to the present invention.

[0029] Figure 4 This is a schematic diagram of an intelligent controller assembly of an embodiment of the rectifier power supply device for a vacuum electric arc furnace according to the present invention. Detailed Implementation

[0030] Referring to the accompanying drawings and specific embodiments, the structure, composition, features, and advantages of the rectifier power supply device and control method for a vacuum electric arc furnace of the present invention will be described below by way of example. However, all descriptions should not be construed as limiting the present invention in any way.

[0031] Furthermore, for any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the various figures, the present invention still allows for any combination or deletion of these technical features (or their equivalents) without any technical obstacle, and thus these further embodiments according to the present invention should also be considered within the scope of this description.

[0032] It should also be noted that the terms "left side", "right side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure.

[0033] Figure 1 This is a schematic diagram of one embodiment of the rectifier power supply device for a vacuum electric arc furnace according to the present invention.

[0034] Figure 1 The overall circuit structure of the rectifier power supply device in this embodiment is shown. It mainly includes two parallel output rectifier branches, namely a low-voltage high-current rectifier component on the left and a front-adjustable boost rectifier component on the right. The low-voltage high-current rectifier component and the front-adjustable boost rectifier component are respectively input to AC power and output DC power in parallel to supply the vacuum electric arc furnace.

[0035] For example, such as Figure 1As shown, the low-voltage high-current rectifier assembly includes a multi-winding transformer, two three-phase five-limb double-reverse star rectifier transformers, thyristors, diodes, circuit breakers, and fuses. It is connected to a 10kV AC power supply via circuit breaker Q1. The input AC power supply is connected to the multi-winding transformer via circuit breaker Q1, as shown by the symbol in the figure. This is a phase-shifting transformer with a Δ-Y-Δ structure, meaning the primary winding is delta-connected, and the secondary side includes two sets of windings, one set with a star (Y) connection and the other with a delta connection. Two independent outputs are drawn from the secondary side. Each output is connected to a thyristor via a fuse. After voltage regulation by the thyristor, it is connected to the primary side of a three-phase five-limb double-reverse star rectifier transformer, as shown by the symbol in the figure. Its primary winding is star-connected, and its secondary winding is double-reverse star-connected. A diode rectifier circuit is connected to the secondary side of each three-phase rectifier transformer. The two rectified DC outputs are combined after passing through a filter reactor and fed into a common DC output terminal, providing a stable low-voltage, high-current power supply to the load (in this invention, the vacuum arc furnace). The main function of the low-voltage, high-current rectifier is to maintain a stable high-current output during the smelting process to support the operating requirements of the vacuum arc furnace. As an example, in this embodiment, the arc voltage is 25V-40VDC and the arc current is above several kA during the constant short-arc state of the smelting process; the power supply requirements during this stage are met by the low-voltage, high-current rectifier. In different embodiments, the low-voltage, high-current rectifier can automatically adjust according to the process settings of its embodiment to achieve stable high-current arc control.

[0036] For example, such as Figure 1 As shown, the adjustable boost rectifier assembly includes components such as a single-phase transformer, a full-bridge rectifier circuit, and a circuit breaker. Its input terminal is connected to a 380V AC power supply via the circuit breaker. It is then connected to the single-phase transformer for voltage transformation, and the transformed voltage enters the full-bridge rectifier circuit composed of thyristors and diodes for rectification. Finally, it is connected to the common DC output terminal via a filter reactor. The main function of the adjustable boost rectifier assembly is to provide a higher open-circuit voltage (no-load voltage) during the arc ignition stage of the vacuum arc furnace, i.e., before the arc is ignited, to ensure stable arc establishment. As an example, the no-load voltage in this embodiment is around 80V. In optional embodiments, the open-circuit voltage output of the boost rectifier circuit can be automatically adjusted according to different smelting furnace settings to achieve ignition and arc-striking functions in smelting.

[0037] The aforementioned rectifier power supply device achieves automatic switching between high-voltage, high-efficiency arc initiation and low-voltage, high-current, reliable arc stabilization by using a pre-adjustable boost rectifier component and a low-voltage, high-current rectifier component in parallel. It also avoids the problem of long-term low-load operation of the main rectifier transformer when using a single rectifier output unit, thereby improving system reliability and energy utilization efficiency.

[0038] Figure 2This is a schematic diagram of a low-voltage, high-current rectifier assembly according to an embodiment of the rectifier power supply device for a vacuum electric arc furnace of the present invention.

[0039] Figure 2 The internal structure of a low-voltage, high-current rectifier assembly according to one embodiment is shown, which includes a multi-winding transformer, a silicon controlled rectifier (SCR) voltage regulation circuit, a three-phase five-limb double-reverse star rectifier transformer, a balancing reactor, a DC filter reactor, and some sampling and protection components.

[0040] For example, such as Figure 2 As shown, the primary side rated voltage of the multi-winding transformer T1 is 10000V, and the secondary side rated voltage is 690V. The primary side of transformer T1 is connected to the AC power supply through circuit breaker QF1; the secondary side has two sets of output windings, providing two independent three-phase AC voltages to drive the subsequent three-phase rectifier transformers T2 and T3. This structure results in a 30° phase difference between the input voltages received by transformers T2 and T3, thereby forming a 12-pulse rectified output in the subsequent rectification process, effectively reducing the harmonic content of the output current. In optional embodiments, other equivalent phase shifting methods can also be adopted.

[0041] For example, such as Figure 2 As shown, two sets of three-phase bridge voltage regulating circuits are respectively set at the secondary output terminal of transformer T1, consisting of thyristors V01, V02, V03 and thyristors V04, V05, V06. Transformer T1 and each thyristor are connected by fuses (such as F1 and F2) to provide overcurrent protection. The voltage regulating unit composed of thyristors V01-V03 controls the input voltage of transformer T2, and the voltage regulating unit composed of thyristors V04-V06 controls the input voltage of transformer T3. By adjusting the firing angle of each thyristor, the voltage amplitude input to the rectifier transformer can be continuously adjusted, thereby precisely controlling the final output DC voltage.

[0042] For example, such as Figure 2 As shown, rectifier transformers T2 and T3 are both three-phase five-limb structures, with their secondary sides using a double-anti-star connection, meaning the secondary side has two windings with opposite polarities, which eliminates DC magnetization of the iron core. The secondary side of transformer T2 is connected in a double-anti-star configuration with six diodes V10~V15, forming two sets of three-phase half-wave rectifier circuits, which are then connected in parallel to produce a 6-pulse output. The five-limb structure, combined with the balancing reactor L1, ensures that two diodes are always conducting simultaneously, reducing diode current and improving the utilization rate of the rectifier transformers. Due to the 30° phase difference between the input voltages of transformers T2 and T3, the two 6-pulse rectifiers, after being connected in parallel, are superimposed on the DC side to form a 12-pulse rectified output, significantly reducing output voltage ripple and harmonic content.

[0043] For example, such as Figure 2As shown, the two rectified outputs are further smoothed by the DC filter reactor L3 to form a stable low-voltage, high-current DC output. At the DC output terminal, a shunt for current sampling and a voltage divider resistor for voltage sampling are provided, along with several capacitors for filtering or voltage equalization, to achieve precise control and improve system stability.

[0044] The structure of the low-voltage high-current rectifier component in this embodiment, as described above, efficiently achieves 12-pulse rectified output, featuring low harmonics and high current output, and is suitable for the power supply requirements of the stable smelting stage of a vacuum electric arc furnace.

[0045] In optional embodiments, the thyristors, diodes, balancing reactors, filter reactors, and shunts in the low-voltage, high-current rectifier assembly are all water-cooled to ensure controllable temperature rise and stable operation under high-current conditions. The water-cooled components use pure water as the cooling medium, which offers good insulation, prevents scaling, and resists corrosion. The cooling channels of the DC-side water-cooled components are integrated through hollow rectangular water-cooled copper busbars and connected to the DC output terminal, achieving integrated conductivity and cooling.

[0046] Figure 3 This is a schematic diagram of a pre-adjustable boost rectifier assembly, representing one embodiment of the rectifier power supply device for a vacuum electric arc furnace according to the present invention.

[0047] Figure 3 The internal structure of a pre-adjustable boost rectifier assembly according to one embodiment is shown, which includes a single-phase transformer, a thyristor, a diode, a filter reactor, and protective components such as circuit breakers and fuses.

[0048] For example, such as Figure 3 As shown, the AC input side of the pre-adjustable boost rectifier is connected to a rated 380V AC power supply. Overload and short circuit protection is provided by circuit breaker QT90 and fuses FT90.1 and FT90.2, and the on / off state is controlled by AC contactor K90.

[0049] For example, such as Figure 3 As shown, the primary side of the single-phase transformer T90 is connected to the AC input through the aforementioned protection components, and the secondary side is connected to the full-bridge rectifier circuit V90, which consists of a thyristor and a diode.

[0050] For example, such as Figure 3 As shown, the full-bridge rectifier circuit V90 consists of thyristors V90.2 and V90.4 and diodes V90.1, V90.3, and V90.5. The gate electrode (G) of the thyristors serves as the control electrode, and the intelligent controller component can trigger the thyristors to turn on and off, achieving controllable rectification of the input voltage. This allows the rectifier circuit to adjust the output voltage as needed, thereby providing a pre-circuit voltage higher than the smelting operating voltage during the arc ignition stage, ensuring successful arc ignition.

[0051] For example, such as Figure 3 As shown, the rectified DC voltage is further smoothed by the filter reactor L4 to reduce ripple and harmonic interference, ensuring output stability. The DC output terminal is equipped with a shunt resistor R90 and voltage divider resistors R91 and R92, which can be used to sample the DC current and voltage, respectively, and feed back to the intelligent controller components for precise regulation. Finally, the DC voltage is output from the DC+ and DC- terminals and connected in parallel to the common DC output terminal of the rectifier power supply unit, working in conjunction with the low-voltage, high-current rectifier components to supply power to the vacuum arc furnace.

[0052] As described above, the pre-adjustable boost rectifier assembly in this embodiment achieves precise control of the output voltage through a single-phase transformer and a full-bridge controllable rectifier circuit, ensuring the high open-circuit voltage required during the arc ignition stage. Combined with a DC filter reactor and a sampling resistor, this assembly provides a stable and smooth DC output, effectively supporting the efficient operation of the vacuum electric arc furnace. Its compact design and flexible adjustment significantly improve the system's reliability and operational flexibility.

[0053] In an optional embodiment, the filter reactor and shunt in the pre-adjustable boost rectifier assembly are both water-cooled, with pure water as the cooling medium, effectively suppressing the risk of overheating.

[0054] Figure 4 This is a schematic diagram of an intelligent controller assembly of an embodiment of the rectifier power supply device for a vacuum electric arc furnace according to the present invention.

[0055] Figure 4 The diagram illustrates the input and output signals of an intelligent controller component according to one embodiment. This embodiment employs a modular, integrated intelligent controller and supports communication with a host system. For ease of description, the component numbers used are consistent with those of the corresponding components in the preceding embodiments.

[0056] For example, such as Figure 4 As shown, the input signals received by the intelligent controller include synchronization signals, voltage / current sampling signals, thermistor signals, and thermal switch signals. The synchronization signals may include synchronization voltage signals TS1 and TS2 from the two three-phase rectifier transformers of the low-voltage high-current rectifier assembly, and synchronization voltage signal TS3 from the unidirectional transformer of the pre-adjustable boost rectifier assembly. These synchronization voltage signals can be used to achieve precise triggering of the thyristor.

[0057] For example, such as Figure 4As shown, multiple voltage / current signals can be acquired through a resistor network, including acquiring the current of each rectifier output circuit through shunt resistors (such as R10, R20, R90), and acquiring the rectified output voltage divider signal through a voltage divider network composed of resistors (such as R14, R15, etc.) at the rectifier output terminal. The current and voltage sampling inputs can be used for status monitoring and closed-loop control. In an optional embodiment, the input signal also includes a sampling signal of the total output voltage / current of the rectifier power supply.

[0058] For example, such as Figure 4 As shown, the intelligent controller also receives temperature monitoring signals from thermistors and thermal switches. Including some sources shown in the figure, the intelligent controller can receive monitoring signals from thermistors installed in each transformer and reactor, and from thermal switches installed in each thyristor, to monitor the temperature status of these components in real time and achieve overheat protection for transformers, reactors, and thyristors.

[0059] For example, such as Figure 4 As shown, the intelligent controller receives and processes various input signals, and accordingly outputs control signals to each thyristor in the low-voltage high-current rectifier component and the pre-adjustable boost rectifier component to control and adjust the power supply output of the rectifier power supply device.

[0060] In an optional embodiment, the intelligent controller component integrates a ProfiNet (PN) communication interface, enabling communication with a host system to achieve centralized monitoring, data traceability, and intelligent scheduling of the vacuum electric arc furnace smelting process. The introduction of PN communication simplifies field wiring and facilitates system integration, significantly improving the system's openness, interoperability, and intelligence, meeting the demands of modern metallurgical equipment for high reliability and information integration.

[0061] Based on the aforementioned rectifier power supply device, this invention also provides a control method for a rectifier power supply suitable for a vacuum electric arc furnace. In one embodiment of this control method, the following steps are included: when the vacuum electric arc furnace has not yet ignited the arc, the output of the pre-adjustable boost rectifier assembly is controlled to be higher than the smelting working voltage to ignite the arc; after detecting that the arc has been established, the thyristor in the pre-adjustable boost rectifier assembly is turned off, while the output of the low-voltage high-current rectifier assembly is automatically adjusted to stably maintain arc combustion; if the arc is unexpectedly extinguished during the melting process, the pre-adjustable boost rectifier assembly is re-engaged to perform a re-arc ignition operation. The above control method can be executed by an intelligent controller assembly.

[0062] Specifically, during the arc ignition stage, the load of the vacuum electric arc furnace is approximately open-circuited. At this time, according to the preset process parameters, the thyristor in the pre-adjustable boost rectifier assembly is adjusted to generate a pre-open-circuit voltage at the DC output terminal that is higher than the normal smelting operating voltage (typically around 80V), which is used to break down the electrode gap and ignite the arc. Since the current is relatively small at this time, the system power consumption is low, avoiding impact on the main rectifier unit (low-voltage high-current rectifier assembly).

[0063] As the electric arc gradually builds up, the load impedance drops rapidly, the DC output current rises quickly, and the load approaches a short circuit. In this embodiment, when the real-time monitored DC output current reaches a preset threshold, it can be determined that the electric arc has been stably ignited. This threshold can be set according to the furnace type, electrode material, and smelting process. At this time, the control thyristor is turned off at zero crossing, thereby cutting off the output of the pre-adjustable boost rectifier component and providing short-circuit protection. At the same time, the low-voltage high-current rectifier component has a certain following voltage output. From this point on, during the stable short-arc smelting process, the thyristor in the low-voltage high-current rectifier circuit component is automatically adjusted according to closed-loop feedback, seamlessly taking over the arc power supply task and stably outputting the set current; this current is set according to the process and is in the range of several kA to tens of kA, ensuring the stable and efficient operation of the smelting process.

[0064] This embodiment also continuously monitors the changing trends of DC output voltage and current during the arc-stabilized smelting process. If the arc suddenly extinguishes during smelting, the rectifier power supply output will exhibit abnormal voltage rise and sudden current drop. By monitoring voltage and current sampling signals in real time, such abnormal characteristics are identified, and after determining that the arc has extinguished, the pre-adjustable boost rectifier component is immediately reactivated to output a high open-circuit voltage again to attempt arc re-ignition, thus avoiding smelting interruption. This automatic re-ignition process can significantly reduce smelting interruption time and improve production continuity.

[0065] The above control method makes full use of the topological advantages of parallel dual rectifier branches, realizing full-process automation of "high voltage arc initiation - high current arc stabilization - abnormal self-recovery", which significantly improves the success rate of arc initiation, arc stability and system safety, while avoiding the problem of low transformer load rate caused by traditional single rectifier power supply taking into account both arc initiation and arc stabilization.

[0066] In an optional embodiment, the control method further includes an overheat protection mechanism. Temperature signals from the thermistors of the transformer and reactor, as well as the thermistors of the thyristor, are continuously collected. If the temperature of any component exceeds the safety limit, power reduction or shutdown is executed to achieve overheat protection. The overheat protection operation can be performed in stages: first, power reduction is implemented; if the temperature continues to rise, the corresponding branch is disconnected; and in extreme cases, shutdown and alarm are triggered.

[0067] In an optional embodiment, operational data and event logs can be uploaded to the host system via the ProfiNet interface, supporting remote intervention and data recording, which facilitates operator monitoring and process optimization.

[0068] In summary, the rectifier power supply device and control method of some embodiments of the present invention are designed based on the arc characteristics of the vacuum electric arc furnace smelting process, and have a high adjustable open-circuit voltage, a low operating voltage and a large operating current; the topology is reasonable, which can fully rectify the load rate of the transformer and has good economic efficiency; the modular integrated intelligent controller component is used for control, the control is stable and reliable, and the protection function is complete; ProfiNet communication is used, which is easy to interconnect with other systems and realize system integration.

[0069] The technical scope of this invention is not limited to the contents of the above specification. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the scope of this invention.

Claims

1. A rectifying power supply device for a vacuum arc furnace, characterized in that, include: A low-voltage, high-current rectifier assembly includes a multi-winding transformer, at least two three-phase five-limb double-reverse star rectifier transformers, a thyristor voltage regulation circuit, and a diode rectifier circuit. The primary side of the multi-winding transformer is connected to an AC power supply, and the secondary side includes multiple windings. The primary side of each three-phase rectifier transformer is connected to the corresponding secondary winding of the multi-winding transformer through a corresponding thyristor voltage regulation circuit. The secondary side of each three-phase rectifier transformer is connected to a corresponding diode rectifier circuit. The pre-adjustable boost rectifier assembly includes a single-phase transformer and a full-bridge rectifier circuit. The primary side of the single-phase transformer is connected to an AC power supply, and the secondary side is connected to the full-bridge rectifier circuit. The full-bridge rectifier circuit includes a thyristor and a diode. The pre-adjustable boost rectifier assembly is connected in parallel with the low-voltage high-current rectifier assembly to output DC power. The intelligent controller component is used to receive the operating status signals of the low-voltage high-current rectifier component and the pre-adjustable boost rectifier component, and control each thyristor according to the received signals. When the vacuum arc furnace has not ignited the arc, the pre-adjustable boost rectifier component is controlled to output a pre-open circuit voltage higher than the smelting working voltage for igniting the arc. After the arc has been established, the low-voltage high-current rectifier component maintains the arc combustion, and performs protection operations when an abnormality is detected.

2. The rectifier power supply device according to claim 1, wherein The primary winding of the multi-winding transformer is connected in a delta configuration, and the secondary winding includes two sets of windings, one set of which is connected in a star configuration and the other set of which is connected in a delta configuration. The number of three-phase five-limb double-reverse star rectifier transformers is two. The secondary side of the two three-phase rectifier transformers is connected to diode rectifier circuits respectively, forming a double-reverse star rectifier structure with a balancing reactor, and forming a 12-pulse rectified output.

3. The rectifier power supply device according to claim 1 or 2, wherein The rectifier power supply device also includes a filter reactor connected to the DC output side and a shunt for current sampling. Furthermore, the thyristor in the thyristor voltage regulation circuit, the diode in the diode rectifier circuit, the filter reactor, and the shunt are all water-cooled.

4. The rectifier power supply device according to claim 3, wherein The low-voltage high-current rectifier assembly is connected to the DC output terminal via a hollow rectangular water-cooled copper busbar. The cooling medium for the water-cooled components in the rectifier power supply device is pure water.

5. The rectifier power supply device according to claim 1, wherein The signals received by the intelligent controller component include the synchronous voltage signal of the AC power supply, the rectified output voltage divider signal, and the current sampling signal sampled using a shunt.

6. The rectifier power supply device as described in claim 5, characterized in that, The intelligent controller component also receives temperature detection signals from the thermistors of the transformer and reactor, and temperature detection signals from the thermistors of the thyristor, and performs overheat protection operation when an abnormal temperature is detected.

7. The rectifier power supply device as described in claim 1, characterized in that, The intelligent controller component adopts an integrated intelligent controller that supports ProfiNet communication.

8. A control method for a rectifier power supply of a vacuum electric arc furnace, characterized in that, The control method is applied to the rectifier power supply device as described in any one of claims 1-7, and the control method includes: Before the electric arc furnace is ignited, the pre-adjustable boost rectifier assembly is controlled to output a pre-open circuit voltage higher than the smelting working voltage to ignite the electric arc. After an electric arc is detected to have been established, the thyristor in the pre-adjustable boost rectifier is turned off. At the same time, the low-voltage high-current rectifier that has been following the voltage output begins to adjust automatically to stably maintain the burning of the electric arc. If the arc is detected to be extinguished during the furnace process, the control will activate the pre-adjustable boost rectifier assembly to reignite the arc.

9. The control method as described in claim 8, characterized in that, The arc is determined by detecting whether the DC output current of the rectifier power supply device reaches a preset current threshold. When the DC output current reaches the current threshold, the thyristor in the pre-adjustable boost rectifier component is turned off.

10. The control method as described in claim 8, characterized in that, During the furnace process, the arc is extinguished by detecting an abnormal drop in the DC output current of the rectifier power supply device. After the arc is extinguished, the pre-adjustable boost rectifier component is automatically activated to reignite the arc.

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