Generalized active soft-switching inversion type welding and cutting power circuit

Abstract

The invention discloses a generalized active soft-switching inversion type welding and cutting power circuit, which comprises an input switch circuit, a primary side rectification filter circuit, a generalized active soft-switching inversion circuit, an isolation transformer, a secondary side rectification filter circuit and a main control panel circuit, wherein the input switch circuit, the primary side rectification filter circuit, the generalized active soft-switching inversion circuit, the isolation transformer, the secondary side rectification filter circuit and the main control panel circuit are sequentially connected with an input power grid of an electric welding and cutting machine according to the flowing direction of a current; and the main control panel circuit is connected with the secondary side rectification filter circuit and the generalized active soft-switching inversion circuit simultaneously. By the generalized active soft-switching inversion type welding and cutting power circuit, a main switching device of an inversion switching device operates under the conditions of zero-current switching-on and zero-voltage switching-off, and an auxiliary switching device operates under the conditions of zero-voltage / zero-current switching-on and zero-voltage / zero-current switching-off.

Description

technical field [0001] The invention relates to the field of inverter electric welding and cutting machines, in particular to a generalized active soft-switching inverter welding and cutting power supply circuit for inverter electric welding machines. Background technique [0002] The high frequency of the PWM inverter is an effective way to improve the control precision and dynamic performance of the inverter welding and cutting power supply, and reduce the consumption of non-ferrous metals such as copper, steel, and aluminum in the inverter welding and cutting power supply. [0003] Through the high frequency of the PWM inverter, the inverter welding and cutting power supply can have a higher power density, save the amount of non-ferrous metals such as copper, steel, aluminum, etc., and make the power supply structure more solid and reliable; and the responsiveness Faster, higher precision of current and voltage control. [0004] However, since the switching loss of power...

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Problems solved by technology

[0005]1. The voltage and current stress of the power switching device of the inverter is very high, and it is easy to fail and be damaged

[0006]2. There is a large voltage and current overlap period on the power switching device of the inverter when it is turned on and off. During this period, the power switching device works in a linear area, resulting in a large power loss during turn-on and turn-off, and the switching device generates serious heat, which is easily damaged by overheating

[0007]3. The switching device of the inverter has a high voltage change rate and current change rate when it is turned on and off, which will generate strong electromagnetic interference. It makes the protection of electromagnetic interference very difficult, and EMC devices are large and complex, and the cost is high

[0008]4. The inverter frequency of ordinary inverter welding and cutting power supply should not be too high, generally within the range not higher than 20KHz, so its power density is not high , copper, steel, aluminum and other non-ferrous metals are also used in large quantities. At the same time, due to the insufficient high inverter frequency, insufficient dynamic response speed, and insufficient high control accuracy, the application of automation and refinement is greatly limited.

[0017] 1. The soft-switching inverter circuit of the phase-shifted full bridge is difficult to meet the soft-switching conditions under no-load, light-load and short-circuit conditions

[0018] 2. Although limited bipolar full-bridge soft switching can meet the conditions of soft switching under no-load, light-load and short-circuit conditions, it needs to connect reactive power inductors in parallel at the primary or secondary of the main transformer

[0019] 3. There is an inherent circulating current that needs to be suppressed, and a DC blocking capacitor is required to suppress the circulating current. The voltage drop of the DC blocking capacitor will lose the voltage on the main transformer; at the same time, it will also lose the duty cycle because of the inherent circulating current. In order to meet the output voltage The requirements of the inverter transformer are often increased, which increases the current stress of the inverter switching device.

[0020] 4. Four sets of power switching semiconductor devices with the same current carrying capacity and withstand voltage are required, and the device cost is relatively high

[0021] 5. The capacitor used to achieve zero-voltage turn-off is directly connected to the two electrodes of each power switching device, so that every time the power switch is turned on, a power switching device directly short-circuits the fully charged capacitor, which will cause the semiconductor of the power switching device Substrate generates local differential Joule heat, causing damage to power semiconductor devices

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