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

Abstract

A generalized active soft-switching inverter welding and cutting power supply circuit of the present invention includes: an input switching circuit, a primary-side rectification and filtering circuit, and a generalized active soft-switching inverter that are sequentially connected to the input power grid of the electric welding and cutting machine according to the direction of current flow. transformer circuit, an isolation transformer, a secondary side rectification filter circuit and a main control board circuit, wherein the main control board circuit is connected with the secondary rectification filter circuit and the generalized active soft switch inverter circuit at the same time; the generalized active soft switch The inverter welding and cutting power supply circuit makes the main switching device of the inverter switching device work under the conditions of zero current on and zero voltage off; the auxiliary switching device works under the conditions of zero voltage / zero current on and zero voltage / zero current off down to work.

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 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 ele...

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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.

[0015]1. It is difficult for the phase-shifted full-bridge soft-switching inverter circuit to meet the soft-switching conditions under no-load, light-load and short-circuit conditions

[0016]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 be in the primary of the main transformer Or secondary and connected reactive power inductance

[0017]3. There is an inherent circulating current that needs to be suppressed, and a DC blocking capacitor is needed 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 is also because Due to the inherent circulating current, it will lose the duty cycle. In order to meet the requirements of the output voltage, the transformation ratio of the inverter transformer is often increased, which increases the current stress of the inverter switching device.

[0018]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

[0019]5. The capacitor used to achieve zero-voltage shutdown is directly connected to the two electrodes of each power switching device, so that there is a power switch every time it is turned on The device directly short-circuits the fully charged capacitor, which will cause local differential Joule heat on the semiconductor substrate of the power switching device, causing damage to the power semiconductor device

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