CN214443792U - Welding control circuit of energy storage welding machine - Google Patents

Abstract

The utility model discloses an energy storage welding machine welding control circuit, its characterized in that: including power, charging circuit, energy storage component, IGBT discharge circuit, current detection unit and the control unit, the full-bridge structure is constituteed by four IGBT to IGBT discharge circuit, the power is connected with energy storage component through charging circuit, energy storage component passes through IGBT discharge circuit and energy storage welding machine's electrode connection, current detection unit's input is connected IGBT discharge circuit's output, current detection unit's output connection control unit's input, charging circuit and IGBT discharge circuit are connected respectively to the control unit's output and are used for charge-discharge control. The utility model discloses a IGBT controls the discharge process through IGBT as the discharge control component of energy storage welding machine, has realized that energy storage welding machine welding current's time is controllable and size is controllable, has solved the problem that energy storage welding machine that adopts the silicon controlled rectifier to discharge can not control discharge time and welding current size.

Description

Welding control circuit of energy storage welding machine

Technical Field

The utility model relates to an energy storage welding machine welding control circuit.

Background

The energy storage welding is also one of resistance welding, the working principle of the energy storage welding is as shown in figure 1, a capacitor is charged by using small current, energy is stored through the capacitor, the charging is stopped after the energy storage is finished, the energy stored in the capacitor is subjected to discharge welding through a welding transformer, the capacitor is charged again after the welding is finished, and the operation is circulated in sequence. The charging can be carried out only after the charging is finished, the charging can be carried out after the discharging is finished, and the charging and the discharging can not be carried out simultaneously. The energy storage welding has the advantages of small impact on a power grid, short welding time, strong explosive force, small heat productivity of workpieces and the like. The welding method is particularly suitable for welding occasions such as stainless steel, nuts, battery connection and the like.

The discharge control of the common energy storage welding machine generally adopts silicon controlled rectifiers, and comprises two forms of a single silicon controlled rectifier and four silicon controlled rectifiers. The single thyristor is adopted for discharging, the circuit is simple, but the welding transformer can only discharge in a single direction, the iron core of the transformer can be magnetized after a long time, and the welding current can be smaller and smaller after the transformer is magnetized, so that the lead of the input end of the transformer must be exchanged after the transformer is used for a period of time (figure 2). The circuit adopting four controllable silicon discharges is relatively complex, a full-bridge structure is formed by VT1-VT4, VT1 and VT4 are simultaneously conducted in a group during discharging, VT2 and VT3 are simultaneously conducted in a group during discharging again, and the current in the transformer is in one forward direction and one reverse direction in sequence and does not have the problem of iron core magnetization (figure 3).

Thyristors, also called thyristors, are known in which the gate is no longer controlled once triggered and is switched off only when the forward current of the thyristor is less than the holding current. When the energy storage welding is in discharging, once the controlled silicon is conducted, the welding current is not controlled, and the capacitor can be charged again only after the welding current is zero and the controlled silicon is in a closed section (figure 4). Because the silicon controlled rectifier can only be turned off after the welding current is less than the maintaining current, the duration time of the whole discharging process is very long, and the welding period is relatively long. As can be seen from the discharge current waveform (fig. 5), the welding current has become very small and has substantially no effect on the weld during the late discharge time period t 2. It can also be seen from the current waveform that the peak value of the current is very high, which is likely to cause welding spatter, and is not allowable for some products.

Disclosure of Invention

The to-be-solved technical problem of the utility model is: the existing energy storage welding machine can not control the discharge time and the welding current.

In order to solve the problem, the technical scheme of the utility model provide an energy storage welding machine welding control circuit, its characterized in that: including power, charging circuit, energy storage component, IGBT discharge circuit, current detection unit and the control unit, the full-bridge structure is constituteed by four IGBT to IGBT discharge circuit, the power is connected with energy storage component through charging circuit, energy storage component passes through IGBT discharge circuit and energy storage welding machine's electrode connection, current detection unit's input is connected IGBT discharge circuit's output, current detection unit's output connection control unit's input, charging circuit and IGBT discharge circuit are connected respectively to the control unit's output and are used for charge-discharge control.

Preferably, the IGBT discharge circuit is connected with an electrode of the energy storage welding machine through a welding transformer.

Preferably, the energy storage element is an energy storage capacitor, and the energy storage capacitor is connected in parallel between the charging circuit and the IGBT discharging circuit.

Preferably, the output end of the control unit is respectively connected with the control ends of the four IGBTs for controlling the on and off of each IGBT.

Preferably, the charging circuit comprises three thyristors and three backward diodes which are connected in series in a reverse direction, the output end of the power supply is respectively connected with the anodes of the three thyristors, and the cathodes of the three thyristors and the anodes of the three diodes are respectively connected with two ends of the energy storage capacitor C.

The current detection unit adopts a Hall current sensor, is arranged in a discharge loop from the IGBT to the welding transformer and is used for detecting the magnitude and the duration time of discharge current when the IGBT is switched on.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model discloses a IGBT controls the discharge process through IGBT as the discharge control component of energy storage welding machine, because IGBT switches on and shuts off through triggering signal, the moment of turn-off can free control, does not receive the influence of main loop current, and the time that has realized energy storage welding machine welding current is controllable and size is controllable, has solved the problem that the energy storage welding machine that adopts the silicon controlled rectifier to discharge can not control discharge time and welding current size. The whole welding period is shortened by controlling the welding time, and the production efficiency is improved; through constant current control, under the condition that the effective values of welding currents are the same, the peak value is greatly reduced, and the splashing phenomenon during welding is effectively inhibited.

Drawings

FIG. 1 is a schematic diagram of the principle of energy storage welding;

FIG. 2 is a schematic diagram of discharge control using a single thyristor;

FIG. 3 is a schematic diagram of discharge control using four controllably switchable silicon;

FIG. 4 is a timing diagram of the discharging operation of the SCR;

FIG. 5 is a waveform diagram of the discharge welding current of the SCR;

fig. 6 is a schematic diagram of the circuit structure of the present invention;

FIG. 7 is a timing diagram of the discharge operation of the IGBT;

fig. 8 is a constant current control current waveform diagram according to the present invention.

Detailed Description

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

As shown in fig. 6, the utility model relates to an energy storage welding machine welding control circuit includes power, charging circuit, energy storage component, IGBT discharge circuit, current detection unit, the control unit, welding transformer, and wherein energy storage component is energy storage electric capacity C.

The charging circuit comprises three thyristors and three backward diodes which are reversely connected in series, the output end of the power supply is respectively connected with the anodes of the three thyristors, and the cathodes of the three thyristors and the anodes of the three diodes are respectively connected with two ends of the energy storage capacitor C. The IGBT discharging circuit is in a full-bridge structure formed by four IGBTs, the four IGBTs are VT1, VT2, VT3 and VT4 respectively, collectors of VT1 and VT3 are connected with one end of an energy storage capacitor C connected with the positive electrode of a power supply respectively, emitters of VT2 and VT4 are connected with one end of a power supply negative electrode respectively, the input end of a welding transformer is connected with emitters of VT1 and VT3 respectively, and the output end of the transformer is connected with an electrode of an energy storage welding machine.

The input end of the current detection unit is connected with the output end of the IGBT discharge circuit, the output end of the current detection unit is connected with the input end of the control unit, the output end of the control unit is respectively connected with the charging circuit and the gate poles of the four IGBTs to control the on and off of the IGBTs and provide required +/-15V driving signals for the IGBTs, the IGBTs are turned on at +15V and the IGBTs are turned off at-15V. The current detection unit adopts a Hall current sensor, is arranged in a discharge loop from the IGBT to the welding transformer and is used for detecting the magnitude and the duration time of discharge current when the IGBT is switched on, and the control unit controls the working condition of the discharge circuit according to the magnitude of the current and the welding time.

The control of the welding time is realized by utilizing the turn-off performance of the IGBT, the welding time can be preset, and the turn-on time of the IGBT is controlled according to the preset welding time. When welding is started for the first time, the energy storage capacitor C is charged through the charging circuit, after charging is completed, the control unit sends out a discharging signal to conduct VT1 and VT4, welding is started when the welding transformer works, the welding time is up, the control unit closes the discharging signal, VT1 and VT4 are turned off, the welding transformer stops working, and welding is completed. When welding again, the VT2 and the VT3 are conducted to discharge, the current direction in the welding transformer is opposite to that of the previous welding, and the VT1 and the VT4 are discharged when welding next time, and the alternating is carried out in sequence, so that the transformer iron core is prevented from being magnetized. By controlling the welding time, the whole welding period is shortened, and the production efficiency is improved, as shown in fig. 7.

Constant current control can be achieved by detecting the welding current during the welding process. The welding current is preset, when the actual welding current reaches a set value, the control unit controls the discharge circuit to be closed, the discharge circuit is opened again after a certain time, and after the actual welding current reaches the set value again, the discharge circuit is closed again, and the operation is repeated until the welding time is finished. As shown in fig. 8, by the constant current control, the peak value is reduced so much that the spatter phenomenon occurring during welding is effectively suppressed when the effective value of the welding current is the same.

Claims (6)

1. The utility model provides an energy storage welding machine welding control circuit which characterized in that: including power, charging circuit, energy storage component, IGBT discharge circuit, current detection unit and the control unit, the full-bridge structure is constituteed by four IGBT to IGBT discharge circuit, the power is connected with energy storage component through charging circuit, energy storage component passes through IGBT discharge circuit and energy storage welding machine's electrode connection, current detection unit's input is connected IGBT discharge circuit's output, current detection unit's output connection control unit's input, charging circuit and IGBT discharge circuit are connected respectively to the control unit's output and are used for charge-discharge control.

2. The welding control circuit of an energy storage welder as defined in claim 1, wherein: and the IGBT discharge circuit is connected with an electrode of the energy storage welding machine through a welding transformer.

3. The welding control circuit of an energy storage welder as defined in claim 1, wherein: the energy storage element is an energy storage capacitor, and the energy storage capacitor is connected in parallel between the charging circuit and the IGBT discharging circuit.

4. The welding control circuit of an energy storage welder as defined in claim 1, wherein: and the output end of the control unit is respectively connected with the control ends of the four IGBTs and used for controlling the on-off of each IGBT.

5. The welding control circuit of an energy storage welder as defined in claim 1, wherein: the charging circuit comprises three thyristors and three backward diodes which are reversely connected in series, the output end of the power supply is respectively connected with the anodes of the three thyristors, and the cathodes of the three thyristors and the anodes of the three diodes are respectively connected with two ends of the energy storage capacitor.

6. The welding control circuit of an energy storage welder as defined in claim 1, wherein: the current detection unit adopts a Hall current sensor, is arranged in a discharge loop from the IGBT to the welding transformer and is used for detecting the magnitude and the duration time of discharge current when the IGBT is switched on.

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