A medium-frequency induction heating power supply device for pipe welding

Abstract

This utility model discloses a medium-frequency induction heating power supply device for pipe welding. The input terminal of the three-phase rectifier bridge 1 is connected to a 380V three-phase power supply. The first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 are connected in series and then in parallel to the output terminal of the three-phase rectifier bridge 1. The positive voltage input terminal of the power module 5 is connected to the positive voltage output terminal of the three-phase rectifier bridge 1. The negative voltage input terminal of the power module 5 is connected to the midpoint of the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2. A fifth IGBT module Q5 is connected in series between the negative voltage input terminal and the negative voltage output terminal of the three-phase rectifier bridge 1. The collector of the fifth IGBT module Q5 is connected to the negative voltage input terminal of the power module 5, and the emitter is connected to the negative voltage output terminal of the three-phase rectifier bridge 1. The output terminal of the power module 5 is connected to the heating coil 7. By setting two voltage dividing capacitors and the fifth IGBT module Q5, the amplitude of the positive and negative half-cycles of the square wave output by the power module has a difference, generating a reverse magnetic field to cancel the residual magnetic field in the pipe.

Description

Technical Field

[0001] This utility model belongs to the technical field of pipeline welding equipment, specifically a medium-frequency induction heating power supply device for pipeline welding. Background Technology

[0002] During the welding process of oil pipelines, the welded area at the pipe opening needs to be heated. Usually, a medium-frequency induction heating coil is fixed at the welded area of ​​the pipeline, and the pipeline is heated by generating eddy currents inside the pipeline.

[0003] Meanwhile, steel oil pipelines generate residual magnetism during manufacturing, transportation, and installation. This residual magnetism can affect welding quality, necessitating demagnetization before welding. To save equipment costs and simplify processes, induction heating power supply devices that simultaneously heat and demagnetize pipelines have emerged on the market. For example, Chinese invention patent CN116232093B discloses an integrated demagnetization and heating device, comprising a three-phase rectifier bridge module, a high-frequency filter capacitor, a DC filter support module, a buffer absorption protection module, a controller, an IGBT power module, and coils. The input of the three-phase rectifier bridge module is connected to a three-phase 380V AC power supply, and the output of the three-phase rectifier bridge module is connected to the controller and the high-frequency filter capacitor. The DC filter support module is connected to the high-frequency filter capacitor, and the buffer absorption protection module is connected to the DC filter support module. Both the buffer absorption protection module and the controller are connected to the IGBT power module, which controls the IGBT power module to generate AC demagnetization, induction heating, and DC demagnetization functions. A single circuit can achieve three functions: AC demagnetization, induction heating, and DC demagnetization, enabling multiple functions in one device without requiring separate circuit structures for each function.

[0004] The aforementioned device generates a reverse magnetic field to counteract the residual magnetic field in the pipe by controlling the pulse width of the positive and negative half-cycles of the square wave output by the power module. It does not require any hardware changes, has a simple structure, and is ingeniously designed. However, when the device integrates AC heating and DC demagnetization, a set of IGBT modules needs to operate in a low conduction state (short pulse width), which can easily lead to low efficiency and severe heat generation of the IGBT modules. Furthermore, the control process for outputting asymmetrical pulse signals is quite complex. Utility Model Content

[0005] This invention proposes a medium-frequency induction heating power supply device for pipe welding, which aims to solve the problems of low power module efficiency and complex signal control process in existing integrated induction heating-demagnetization equipment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A medium-frequency induction heating power supply device for pipe welding includes a three-phase rectifier bridge 1, a power module 5, a first voltage-dividing capacitor C1, a second voltage-dividing capacitor C2, a control module, and a heating coil. The input terminal of the three-phase rectifier bridge 1 is connected to a 380V three-phase power supply. The first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 are connected in series and then in parallel to the output terminal of the three-phase rectifier bridge 1. The positive voltage input terminal of the power module 5 is connected to the positive voltage output terminal of the three-phase rectifier bridge 1, and the negative voltage input terminal of the power module 5 is connected to the midpoint of the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2. A fifth IGBT module Q5 is connected in series between the negative voltage input terminal of the power module 5 and the negative voltage output terminal of the three-phase rectifier bridge 1. The collector of the fifth IGBT module Q5 is connected to the negative voltage input terminal of the power module 5, and the emitter of the fifth IGBT module Q5 is connected to the negative voltage output terminal of the three-phase rectifier bridge 1. The output terminal of the power module 5 is connected to the heating coil 7. The control module is used to output PWM signals to the power module 5 and the fifth IGBT module Q5. The power module 5 is used to output medium-frequency alternating current to the heating coil 7 according to the PWM signal. The switching period and pulse width of the fifth IGBT module Q5 are synchronized with the power module 5.

[0007] Preferably, the power module 5 includes a first IGBT module Q1, a second IGBT module Q2, a third IGBT module Q3, and a fourth IGBT module Q4. The collectors of the first IGBT module Q1 and the second IGBT module Q2 are connected to the positive voltage input terminal of the power module 5. The emitter of the first IGBT module Q1 is connected to the collector of the third IGBT module Q3. The emitter of the second IGBT module Q2 is connected to the collector of the fourth IGBT module Q4. The emitters of the third IGBT module Q3 and the fourth IGBT module Q4 are connected to the negative voltage input terminal of the power module 5. The gates of the first to fourth IGBT modules Q1-Q4 are connected to the control module.

[0008] Preferably, the second voltage divider capacitor C2 is an adjustable capacitor, and the voltage division ratio of the first voltage divider capacitor C1 to the second voltage divider capacitor C2 is (5~9):10.

[0009] Preferably, it also includes a shorting switch K1, which is connected in parallel between the collector and emitter of the fifth IGBT module Q5.

[0010] Preferably, the control module includes a microcontroller 2, a PWM controller 4, and a gate driver 3. The microcontroller 2 is communicatively connected to the PWM controller 4. The output terminal of the PWM controller 4 is connected to the input terminal of the gate driver 3. The output terminal of the gate driver 3 is connected to the gates of the first to fifth IGBT modules Q1-Q5, respectively.

[0011] Preferably, it also includes a magnetic sensor 6 for detecting the residual magnetic field of the pipeline, wherein the signal output terminal of the magnetic sensor 6 is connected to the input terminal of the microcontroller 2.

[0012] Beneficial effects: Compared with the prior art, the present invention can achieve at least the following technical effects: 1. By setting two voltage-dividing capacitors and an IGBT module, this utility model can change the input voltage of the power module when it is in different conduction directions, thereby making the amplitude of the positive and negative half-cycles of the square wave output by the power module have a difference, generating a reverse magnetic field to cancel the residual magnetic field in the pipe. Using one device, demagnetization can be achieved at the same time as heating, saving equipment costs and simplifying the process.

[0013] 2. Compared with the existing technology that achieves simultaneous heating and demagnetization by adjusting the pulse width of the power module, this utility model achieves simultaneous heating and demagnetization by controlling the input voltage of the power module, thus avoiding the problems of low efficiency in the low conduction state of the power module and complex control algorithms. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the circuit structure of this utility model.

[0015] Figure 2 The output waveform diagram of this utility model when heating and demagnetizing are performed simultaneously (A is the positive half-cycle voltage bias, B is the negative half-cycle voltage bias).

[0016] Figure 3 This is the output waveform diagram of the present invention when heating at full power.

[0017] In the diagram: 1. Three-phase rectifier bridge; 2. Microcontroller; 3. Gate driver; 4. PWM controller; 5. Power module; 6. Magnetic sensor; 7. Heating coil. Detailed Implementation

[0018] The present invention will be further explained below with reference to specific implementation examples.

[0019] Please see Figure 1-3This utility model proposes a medium-frequency induction heating power supply device for pipe welding, including a three-phase rectifier bridge 1, a power module 5, a first voltage dividing capacitor C1, a second voltage dividing capacitor C2, a control module, and a heating coil. The input terminal of the three-phase rectifier bridge 1 is connected to a 380V three-phase power supply. The first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 are connected in series and then in parallel to the output terminal of the three-phase rectifier bridge 1. The positive voltage input terminal of the power module 5 is connected to the positive voltage output terminal of the three-phase rectifier bridge 1, and the negative voltage input terminal of the power module 5 is connected to the midpoint of the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2. A fifth IGBT module Q5 is connected in series between the negative voltage input terminal of the power module 5 and the negative voltage output terminal of the three-phase rectifier bridge 1. The collector of the fifth IGBT module Q5 is connected to the negative voltage input terminal of the power module 5, and the emitter of the fifth IGBT module Q5 is connected to the negative voltage output terminal of the three-phase rectifier bridge 1. The output terminal of the power module 5 is connected to the heating coil 7. The control module is used to output PWM signals to the power module 5 and the fifth IGBT module Q5. The power module 5 is used to output medium-frequency alternating current to the heating coil 7 according to the PWM signal. The switching period and pulse width of the fifth IGBT module Q5 are synchronized with the power module 5.

[0020] The power module 5 includes a first IGBT module Q1, a second IGBT module Q2, a third IGBT module Q3, and a fourth IGBT module Q4. The collectors of the first IGBT module Q1 and the second IGBT module Q2 are connected to the positive voltage input terminal of the power module 5. The emitter of the first IGBT module Q1 is connected to the collector of the third IGBT module Q3. The emitter of the second IGBT module Q2 is connected to the collector of the fourth IGBT module Q4. The emitters of the third IGBT module Q3 and the fourth IGBT module Q4 are connected to the negative voltage input terminal of the power module 5. The gates of the first to fourth IGBT modules Q1-Q4 are connected to the control module.

[0021] like Figure 1 As shown, the three-phase rectifier bridge 1 is used to convert the 380V three-phase power frequency input into DC output to power the power module 5. To make the output of the three-phase rectifier bridge 1 more stable, a smoothing capacitor C3 is connected in parallel between the two output terminals of the three-phase rectifier bridge 1 in this embodiment. In this embodiment, the power module 5 adopts the full-bridge IGBT mode, wherein the first IGBT module Q1 and the fourth IGBT module Q4 (hereinafter referred to as the first IGBT module group) are switched on and off synchronously, and the second IGBT module Q2 and the third IGBT module Q3 (hereinafter referred to as the second IGBT module group) are switched on and off synchronously. The control module controls the two IGBT module groups to conduct alternately to change the direction of the output voltage of the power module 5, thereby enabling the power module 5 to output medium-frequency alternating current to the heating coil 7. Taking the voltage at the output terminal on the left side of the power module (between the emitter of the first IGBT module Q1 and the collector of the third IGBT module Q3) as a reference point, when heating and demagnetizing occur simultaneously, the power module 5 has two output forms: In one mode, when the fifth IGBT module Q5 is synchronously turned on with the first module group, the fifth IGBT module Q5 short-circuits the second voltage divider capacitor C2. The input voltage of the power module 5 is the output voltage Vdc of the three-phase rectifier bridge 1. The current flows sequentially through the second IGBT module Q2, the heating coil 7, the third IGBT module Q3, and the fifth IGBT module Q5. When the fifth IGBT module Q5 is synchronously turned off with the first module group, the input voltage of the power module 5 becomes the voltage across the first voltage divider capacitor C1. The first voltage divider capacitor C1 discharges into the power module 5. The current flows from the positive terminal of the first voltage divider capacitor C1 through the first IGBT module Q1, the heating coil, the fourth IGBT module Q4, and back to the negative terminal of the first voltage divider capacitor C1 (the charging resistance of the first voltage divider capacitor is close to 0, so the charging delay of the first voltage divider capacitor can be ignored at intermediate frequency output). At this time, the output waveform of the power module 5 is as follows: Figure 2 As shown in (A).

[0022] In another mode, when the fifth IGBT module Q5 is synchronously turned on with the second module group, the fifth IGBT module Q5 short-circuits the second voltage divider capacitor C2. The input voltage of the power module 5 is the output voltage Vdc of the three-phase rectifier bridge 1. The current flows sequentially through the first IGBT module Q1, the heating coil 7, the fourth IGBT module Q4, and the fifth IGBT module Q5. When the fifth IGBT module Q5 is synchronously turned off with the first module group, the input voltage of the power module 5 becomes the voltage across the first voltage divider capacitor C1. The first voltage divider capacitor C1 discharges into the power module 5, and the current flows from the positive terminal of the first voltage divider capacitor C1 sequentially through the second IGBT module Q2, the heating coil, the third IGBT module Q3, and back to the negative terminal of the first voltage divider capacitor C1. At this time, the output waveform of the power module 5 is as follows: Figure 2 As shown in (B).

[0023] In both modes, bias currents in opposite directions can be generated in the heating coil 7, thereby producing magnetic fields in opposite directions in the heating coil. Users can select the corresponding output mode based on the direction of residual magnetism in the pipe that has been measured in advance.

[0024] When this device is in full-power heating mode, the fifth IGBT module Q5 is in a constant conducting state, and the power module output waveform is as follows: Figure 3 As shown. In this embodiment, the second voltage divider capacitor C2 is an adjustable capacitor, and the voltage division ratio of the first voltage divider capacitor C1 to the second voltage divider capacitor C2 is (5~9):10.

[0025] In this embodiment, the second voltage divider capacitor C2 is set as an adjustable capacitor, which facilitates the adjustment of the input voltage of the power module 5 when the fifth IGBT module Q5 is off.

[0026] This embodiment is further configured to include a shorting switch K1, which is connected in parallel between the collector and emitter of the fifth IGBT module Q5.

[0027] When the device is operating in full-power heating mode, in order to avoid losses caused by the fifth IGBT module Q5 being turned on for a long time, the short-circuit switch K1 can be closed, while keeping the fifth IGBT module Q5 in the off state.

[0028] In this embodiment, the control module is further configured to include a microcontroller 2, a PWM controller 4, and a gate driver 3. The microcontroller 2 is communicatively connected to the PWM controller 4, the output terminal of the PWM controller 4 is connected to the input terminal of the gate driver 3, and the output terminal of the gate driver 3 is connected to the gates of the first to fifth IGBT modules Q1-Q5 respectively.

[0029] This embodiment also includes a magnetic sensor 6 for detecting the residual magnetic field of the pipeline, and the signal output terminal of the magnetic sensor 6 is connected to the input terminal of the microcontroller 2.

[0030] The direction and magnitude of the residual magnetism in the pipe are detected by the magnetic sensor 6. Based on the signal feedback from the magnetic sensor 6, the microcontroller 2 controls the output mode of the power module 5 and the fifth IGBT module Q5 through the PWM controller 4 and the gate driver 3.

[0031] In the description of this utility model, the term "multiple" refers to two or more. Unless otherwise explicitly defined, the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model. The terms "connection," "installation," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0032] In the description of this utility model, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this utility model, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0033] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A medium-frequency induction heating power supply device for pipe welding, characterized in that, The system includes a three-phase rectifier bridge (1), a power module (5), a first voltage divider capacitor C1, a second voltage divider capacitor C2, a control module, and a heating coil. The input terminal of the three-phase rectifier bridge (1) is connected to a 380V three-phase power frequency power supply. The first voltage divider capacitor C1 and the second voltage divider capacitor C2 are connected in series and then in parallel to the output terminal of the three-phase rectifier bridge (1). The positive voltage input terminal of the power module (5) is connected to the positive voltage output terminal of the three-phase rectifier bridge (1). The negative voltage input terminal of the power module (5) is connected to the midpoint of the first voltage divider capacitor C1 and the second voltage divider capacitor C2. A fifth IGBT module Q5 is connected in series between the negative voltage input terminal of the power module (5) and the negative voltage output terminal of the three-phase rectifier bridge (1). The collector of the fifth IGBT module Q5 is connected to the negative voltage input terminal of the power module (5). The emitter of the fifth IGBT module Q5 is connected to the negative voltage output terminal of the three-phase rectifier bridge (1). The output terminal of the power module (5) is connected to the heating coil (7). The control module is used to output PWM signals to the power module (5) and the fifth IGBT module Q5. The power module (5) is used to output medium-frequency alternating current to the heating coil (7) according to the PWM signal. The switching period and pulse width of the fifth IGBT module Q5 are synchronized with the power module (5).

2. The medium-frequency induction heating power supply device for pipe welding according to claim 1, characterized in that, The power module (5) includes a first IGBT module Q1, a second IGBT module Q2, a third IGBT module Q3, and a fourth IGBT module Q4. The collectors of the first IGBT module Q1 and the second IGBT module Q2 are connected to the positive voltage input terminal of the power module (5). The emitter of the first IGBT module Q1 is connected to the collector of the third IGBT module Q3. The emitter of the second IGBT module Q2 is connected to the collector of the fourth IGBT module Q4. The emitters of the third IGBT module Q3 and the fourth IGBT module Q4 are connected to the negative voltage input terminal of the power module (5). The gates of the first to fourth IGBT modules Q1-Q4 are connected to the control module.

3. The medium-frequency induction heating power supply device for pipe welding according to claim 1, characterized in that, The second voltage divider capacitor C2 is an adjustable capacitor, and the voltage division ratio of the first voltage divider capacitor C1 to the second voltage divider capacitor C2 is (5~9):

10.

4. The medium-frequency induction heating power supply device for pipe welding according to claim 1, characterized in that, It also includes a shorting switch K1, which is connected in parallel between the collector and emitter of the fifth IGBT module Q5.

5. The medium-frequency induction heating power supply device for pipe welding according to claim 1, characterized in that, The control module includes a microcontroller (2), a PWM controller (4) and a gate driver (3). The microcontroller (2) is communicatively connected to the PWM controller (4). The output terminal of the PWM controller (4) is connected to the input terminal of the gate driver (3). The output terminal of the gate driver (3) is connected to the gates of the first to fifth IGBT modules Q1-Q5 respectively.

6. The medium-frequency induction heating power supply device for pipe welding according to claim 5, characterized in that, It also includes a magnetic sensor (6) for detecting the residual magnetic field in the pipeline, the signal output terminal of which is connected to the input terminal of the microcontroller (2).

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