High-power resistance welding inverter power supply parallel circuit

Abstract

The utility model discloses a high-power resistance welding inverter power supply parallel circuit in the technical field of resistance welding, which comprises a three-phase live wire, diodes, capacitors, a bridge circuit 1, a bridge circuit 2 and a conveying end, the three-phase live wire comprises a phase line L1, a phase line L2 and a phase line L3, the diodes comprise a diode D1, a diode D2, a diode D3, a diode D4, a diode D5 and a diode D6, the capacitors comprise a capacitor C, and the bridge circuit 1 is connected with the conveying end. The structure is reasonable, many problems caused by inductance current sharing can be avoided by adopting a bridge circuit parallel magnetic ring current sharing method, the magnetic ring is installed between an inverter power supply and a welding transformer, no special designated position exists, the magnetic ring is a magnetizer, the magnetic resistance is very small, and most of magnetic lines are located in the magnetic ring, so that the magnetic resistance is very small. The magnetic ring is simple in structure, free of induction to surrounding metal, simple in using method, low in cost, good in current sharing effect and the like, and an output line of the inverter power supply only needs to penetrate through the magnetic ring according to a certain rule.

Description

Technical Field

[0001] The utility model relates to the technical field of resistance welding, in particular to a high-power resistance welding inverter power supply parallel circuit. Background Art

[0002] As the application scope of resistance welding becomes wider and wider, its power is also increasing. For high-power resistance welding inverter power supply, the internal inverter device IGBT needs to be used in parallel. When IGBT is used in parallel, current must be equalized to ensure that the current error flowing through each IGBT is within the allowable range. Resistance welding is a welding method in which the workpiece to be welded is fixed by a certain pressure, and then a large current is passed through it. The workpiece itself is heated by the resistance of the workpiece itself and the contact resistance of the workpiece, so that the workpiece itself is fused together. The resistance welding inverter power supply adopts three-phase power supply. After rectification and filtering, the three-phase power supply enters the inverter circuit. The inverter circuit consists of 4 IGBTs in a bridge structure. The inverter output end is connected to the input end of the welding transformer, and the voltage is reduced by the welding transformer and added to the two ends of the electrode. During welding, the electrode forms a loop through the workpiece, generating a large welding current. The size of the welding current is related to the workpiece and the process. The larger the welding spot area of ​​the workpiece, the larger the welding current required.

[0003] This type of welding machine that uses an inverter to provide power to the welding transformer is called an inverter welding machine. Figure 1 At present, the power of inverter welding machines has increased from tens of kW and hundreds of kW to thousands of kW or even several thousand kW, and the welding current has reached more than 200kA. According to the welding voltage of 10V, the turns ratio of the transformer is 50 / 1, and the primary current of the transformer must reach 200kA / 50=4000A. For the inverter power supply, it is also necessary to provide 4000A current. The current specification of the commonly used IGBT module is 1400A, which requires 4 IGBT modules to be used in parallel.

[0004] IGBT parallel connection is divided into direct parallel connection and indirect parallel connection. Direct parallel connection is to connect the C poles and E poles of two or more IGBTs together, without using current sharing devices, and completely rely on the symmetry of each IGBT circuit and the consistency of the IGBT's own parameters. This method is relatively easy to implement for the parallel connection of two IGBTs. When multiple IGBTs are connected in parallel, the symmetry of each circuit is difficult to ensure, and it is even more impossible to keep the parameters of each IGBT consistent. IGBT parameters are divided into static parameters and dynamic parameters. Dynamic parameters are generally difficult to measure accurately, requiring special equipment and expensive. This method is generally applicable to the occasion of two IGBTs in parallel. Indirect parallel connection generally connects one of the C and E poles of each IGBT directly together, and the other pole is connected through a current sharing inductor. This method is also called bridge arm parallel connection. This method has relatively low requirements on the parameters of IGBT and the symmetry of each IGBT circuit, and has relatively high requirements on the installation of the current sharing inductor. The inductance of the current-sharing inductor is very small, and it is generally an air-core structure. A certain amount of space must be left around the current-sharing inductor to prevent the magnetic field generated by the inductor from inducing the surrounding metal and causing heating. When this method is used in parallel, the volume of the whole machine will be much larger. This method cannot be implemented for multiple IGBTs in parallel.

[0005] Therefore, it is necessary to develop a high-power resistance welding inverter power supply parallel circuit. Utility Model Content

[0006] The purpose of the utility model is to provide a high-power resistance welding inverter power parallel circuit. The utility model adopts a bridge circuit parallel magnetic ring current equalization method to avoid many problems caused by inductor current equalization. The installation position of the magnetic ring only needs to be between the inverter power supply and the welding transformer, and there is no special designated position. The magnetic ring is a magnetic conductor with very small magnetic resistance. Most of the magnetic lines of force are inside the magnetic ring and will not cause induction to the surrounding metal. The method of use is also very simple. It only needs to pass the output line of the inverter power supply through the magnetic ring according to certain rules. At the same time, the method is simple, low cost, good current equalization effect, etc., so as to solve the problem that multiple IGBTs cannot be connected in parallel when parallel is proposed in the above background technology.

[0007] To achieve the above object, the utility model provides the following technical solution: a high-power resistance welding inverter power parallel circuit, including a three-phase live wire, a diode, a capacitor, a bridge 1, a bridge 2 and a transmission end, the three-phase live wire includes a phase line L1, a phase line L2 and a phase line L3, the diode includes a diode D1, a diode D2, a diode D3, a diode D4, a diode D5 and a diode D6, and the capacitor includes a capacitor C;

[0008] The bridge circuit 1 includes voltages V11, V21, V31 and V41, the bridge circuit 2 includes voltages V12, V22, V32 and V42, and the delivery ends include delivery ends X11, X12, X21 and X22.

[0009] Preferably, the phase line L1, the phase line L2 and the phase line L3 are connected to the diode D1, the diode D2, the diode D3, the diode D4, the diode D5 and the diode D6, and the diode D1, the diode D2, the diode D3, the diode D4, the diode D5 and the diode D6 are connected to the capacitor C.

[0010] Preferably, the capacitor C is connected to the voltage V11, the voltage V21, the voltage V31, the voltage V41, the voltage V12, the voltage V22, the voltage V32 and the voltage V42 respectively.

[0011] Preferably, the voltage V11, the voltage V21, the voltage V31 and the voltage V41 are connected to the delivery end X11 and the delivery end X21, and the voltage V12, the voltage V22, the voltage V32 and the voltage V42 are connected to the delivery end X12 and the delivery end X22.

[0012] Preferably, the delivery end X11, the delivery end X12, the delivery end X21 and the delivery end X22 are connected to a welding transformer.

[0013] Compared with the prior art, the beneficial effects of the utility model are:

[0014] The utility model adopts the method of equalizing the current by bridge parallel magnetic rings to avoid many problems caused by inductive current equalization. The installation position of the magnetic ring only needs to be between the inverter power supply and the welding transformer, and there is no specially designated position. The magnetic ring is a magnetic conductor with very small magnetic resistance. Most of the magnetic lines of force are inside the magnetic ring and will not cause induction to the surrounding metal. The method of use is also very simple. It is only necessary to pass the output line of the inverter power supply through the magnetic ring according to certain rules. At the same time, the method is simple, the cost is low, and the current equalization effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the inverter welding machine provided by the utility model;

[0016] Figure 2 This is a schematic diagram of direct parallel connection of IGBTs provided by the utility model;

[0017] Figure 3 This is a schematic diagram of the parallel connection of IGBT bridge arms provided by the utility model;

[0018] Figure 4 A schematic diagram of the parallel connection of IGBT bridges provided by the utility model;

[0019] Figure 5 The full-bridge inverter IGBT working timing diagram provided by the utility model;

[0020] Figure 6 A diagram showing a method for connecting three bridges in parallel provided by the utility model;

[0021] Figure 7 FIG2 is a diagram of a method for connecting three bridges in parallel provided by the utility model. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] The utility model provides the following technical solutions: high-power resistance welding inverter power parallel circuit, please refer to Figure 1-7 , including a three-phase live wire, a diode, a capacitor, a bridge 1, a bridge 2 and a transmission end, the three-phase live wire includes a phase line L1, a phase line L2 and a phase line L3, the diode includes a diode D1, a diode D2, a diode D3, a diode D4, a diode D5 and a diode D6, the capacitor includes a capacitor C, the phase line L1, the phase line L2 and the phase line L3 are connected with the diode D1, the diode D2, the diode D3, the diode D4, the diode D5 and the diode D6, and the diode D1, the diode D2, the diode D3, the diode D4, the diode D5 and the diode D6 are connected with the capacitor C;

[0024] Bridge circuit 1 includes voltage V11, voltage V21, voltage V31 and voltage V41, bridge circuit 2 includes voltage V12, voltage V22, voltage V32 and voltage V42, the delivery end includes delivery end X11, delivery end X12, delivery end X21 and delivery end X22, capacitor C is connected to voltage V11, voltage V21, voltage V31, voltage V41, voltage V12, voltage V22, voltage V32 and voltage V42 respectively, voltage V11, voltage V21, voltage V31 and voltage V41 are connected to delivery end X11 and delivery end X21, voltage V12, voltage V22, voltage V32 and voltage V42 are connected to delivery end X12 and delivery end X22, and delivery end X11, delivery end X12, delivery end X21 and delivery end X22 are connected to welding transformer.

[0025] Working principle: When using the utility model, the inverter part is composed of voltage V11, voltage V21, voltage V31, and voltage V41 to form bridge circuit 1, and the transmission end is transmission end X11 and transmission end X21. The voltage V12, voltage V22, voltage V32, and voltage V42 form bridge circuit 2, and the transmission end is transmission end X12 and transmission end X22. The voltage V11 and voltage V41 in bridge circuit 1 and the voltage V12 and voltage V42 in bridge circuit 2 have the same trigger timing, and the voltage V21 and voltage V31 in bridge circuit 1 and the voltage V22 and voltage V32 in bridge circuit 2 have the same trigger timing. Figure 5 .

[0026] Two bridge circuits in parallel require two magnetic rings. The delivery ends X11 and X21 share one magnetic ring, and the delivery ends X12 and X22 share one magnetic ring. The connecting wires used by the delivery ends X11 and X21 must have equal diameters and lengths. The connecting wires used by the delivery ends X12 and X22 must have equal diameters and lengths. The connecting wire of the delivery end X11 passes through the A side of the magnetic ring, and the connecting wire of the delivery end X21 passes through the B side of the magnetic ring. The two connecting wires pass through the magnetic ring from two directions respectively, not the same direction. Similarly, the connecting wires of the delivery ends X12 and X22 also pass through another magnetic ring in the same way.

[0027] The direction of the magnetic flux generated in the magnetic ring by the current in the transmission end X11 is opposite to the direction of the magnetic flux generated in the magnetic ring by the current in the transmission end X12. When the currents in the transmission end X11 and the transmission end X21 are equal, the magnetic fluxes in the two directions in the magnetic ring cancel each other out, which is equivalent to the magnetic ring having no effect. When the currents in the transmission end X11 and the transmission end X21 are inconsistent, magnetic flux is generated in the magnetic ring, thereby generating reactance, which hinders the current from increasing or decreasing, and finally makes the two currents consistent. The current changes in the transmission end X12 and the transmission end X22 are the same.

[0028] Three bridge circuits in parallel method 1 can refer to Figure 6, three bridges in parallel require 6 magnetic rings. The transmission ends X11, X12, and X13 share 3 magnetic rings, and the transmission ends X21, X22, and X23 share another three magnetic rings. The connecting wires used by the transmission ends X11, X21, and X31 must have equal diameters and lengths, and the connecting wires used by the transmission ends X12, X22, and X23 must have equal diameters and lengths. The connecting wire transmission end X11 passes through the magnetic ring 1 from the A side to the B side, and then passes through the magnetic ring 2 from the B side to the A side. The connecting wire transmission end X12 passes through the magnetic ring 2 from the A side to the B side, and then passes through the magnetic ring 3 from the B side to the A side. The connecting wire transmission end X13 passes through the magnetic ring 3 from the A side to the B side, and then passes through the magnetic ring 1 from the B side to the A side. Each magnetic ring is passed through two connecting wires with different current directions. If there is a current imbalance, the magnetic ring will generate reactance to suppress the difference in current. This connection method allows each bridge to restrain and balance each other.

[0029] Method 2 for connecting three bridges in parallel can be referred to Figure 7 In actual use, there is another method. When three bridge circuits are connected in parallel, only four magnetic rings are needed, and the current sharing effect is the same. The connecting line transmission end X11 passes through the magnetic ring 1 from the A side to the B side, and then passes through the magnetic ring 2 from the A side to the B side. The connecting line transmission end X12 passes through the magnetic ring 1 from the B side to the A side, and the connecting line transmission end X13 passes through the magnetic ring 2 from the B side to the A side. This method not only saves one magnetic ring, but also makes the connection simpler.

[0030] The parallel connection of multiple bridge circuits has the same principle as the parallel connection of three bridge circuits, and they can be connected according to the same rules. The utility model adopts the method of bridge circuit parallel magnetic ring current sharing to avoid many problems caused by inductor current sharing. The installation position of the magnetic ring only needs to be between the inverter power supply and the welding transformer, and there is no specially designated position. The magnetic ring is a magnetic conductor with very small magnetic resistance. Most of the magnetic lines of force are inside the magnetic ring and will not cause induction to the surrounding metal. The method of use is also very simple. It is only necessary to pass the output line of the inverter power supply through the magnetic ring according to certain rules. At the same time, the method is simple, low cost, and good current sharing effect.

[0031] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A high-power resistance welding inverter power parallel circuit, comprising a three-phase live wire, a diode, a capacitor, a bridge 1, a bridge 2 and a transmission end, characterized in that: The three-phase live wire includes a phase line L1, a phase line L2 and a phase line L3, the diode includes a diode D1, a diode D2, a diode D3, a diode D4, a diode D5 and a diode D6, the capacitor includes a capacitor C, the phase line L1, the phase line L2 and the phase line L3 are connected to the diode D1, the diode D2, the diode D3, the diode D4, the diode D5 and the diode D6, and the diode D1, the diode D2, the diode D3, the diode D4, the diode D5 and the diode D6 are connected to the capacitor C; The bridge circuit 1 includes voltages V11, V21, V31 and V41, the bridge circuit 2 includes voltages V12, V22, V32 and V42, the capacitor C is connected to the voltages V11, V21, V31, V41, V12, V22, V32 and V42 respectively, the delivery end includes delivery end X11, X12, X21 and X22, the voltages V11, V21, V31 and V41 are connected to the delivery end X11 and X21, the voltages V12, V22, V32 and V42 are connected to the delivery end X12 and X22, and the delivery ends X11, X12, X21 and X22 are connected to the welding transformer.

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