Asymmetrical half-bridge zero-voltage soft switching inverter type welding and cutting machine

Abstract

The invention discloses an asymmetrical half-bridge zero-voltage soft switching inverter type welding and cutting machine, which comprises an input filtering circuit, a primary side rectifier filtering circuit, an asymmetrical half-bridge soft switching inverter circuit, an isolation transformer circuit, a secondary side rectifier filtering circuit and a master control board circuit, wherein the asymmetrical half-bridge soft switching inverter circuit comprises a main inverter circuit half-bridge consisting of a first insulated gate field effect power switch device and a second insulated gatefield effect power switch device, as well as a first driving resistor, a second driving resistor, a first resonant capacitor, a second resonant capacitor, a saturated inductor and a stopping condenser; the central point of a bridge arm of the main inverter circuit is connected with an intermediate-frequency transformer through the stopping condenser; the saturated inductor, the first and the second resonant capacitors and a leakage inductor of the intermediate-frequency transformer form a soft switching resonant circuit. The asymmetrical half-bridge zero-voltage soft switching inverter type welding and cutting machine is simple in structure and low in implementation cost, and the switching voltage stress and current stress are reduced considerably.

Description

technical field [0001] The invention relates to the field of inverter welding machines, in particular to an inverter welding and cutting machine with an asymmetric half-bridge soft switch structure. Background technique [0002] At present, high frequency has become an important feature of the inverter welding and cutting power supply. High frequency can make the inverter welding and cutting power supply have a higher power density, and save the amount of copper, steel, aluminum and other non-ferrous metals. The power structure is more solid and reliable; and the response capability is faster, and the current and voltage control precision is higher. [0003] However, since the switching loss of power electronic switching devices is proportional to the inverter frequency, the higher the frequency, the greater the loss of devices and circuits, and the lower the efficiency of the inverter. Therefore, the welding and cutting performance and energy efficiency ratio of ordinary i...

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Problems solved by technology

[0004] 1. The voltage and current stress of the power switching device of the inverter is very large, and it is easy to fail and be damaged

[0005] 2. There is a large voltage and current overlap period on the power switch device of the inverter when it is turned on and off. During this period, the power switch device works in the linear region, which causes a large power loss during the turn-on and turn-off period. The switching device generates a lot of heat and is easily damaged by overheating

[0006] 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, making it difficult to protect electromagnetic interference, and the EMC device is large and complex ,high cost

[0007] 4. The inverter frequency of ordinary inverter welding and cutting power supply should not be too high, generally it can only be within the range of no higher than 20KHz, so its power density is not large, and the amount of non-ferrous metals such as copper, steel, and aluminum is also large. , and at the same time, due to the insufficient high inverter frequency, insufficient dynamic response speed, and insufficient high control accuracy, it greatly limits its application in automation and refinement.

[0011] 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

[0012] 2. There is an inherent circulating current that needs to be suppressed. For this reason, the PWM circuit 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.

[0013] 3. 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

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