Frequency-Controlled Inverter Power Supply for Spot Welding basedon Transformer Leakage Inductance

摘要

In the frequency-controlled inverter power supplies, the reactance component of the transformer connected a the inverter is proportional to the power supply frequency. Transformer leakage inductance as seen from the mary winding of the transformer is known to decrease as the power supply frequency increases. This signifies that rely controlling the power supply frequency may not be sufficient to control transformer secondary current over a -le range. This paper discusses the possibility of a frequency-controlled inverter power supply. Experimental results licate that it is possible. Control of an actual welding current with a frequency-controlled inverter power supply s found to require a non-inductive current sensor Thus, a current sensor consisting of two copper pipes is roduced. PWM inverter power supplies that utilize IGBTs capable of driving induction motors at variable speeds well known. In recent years, research into reducing IGBT switching losses has intensified due to increasedinterest in issues concerning energy conservation and the global environment. The frequency-controlled inverterpower supply, unlike the PWM design, does not require high-frequency switching, and therefore contributes toreduced switching losses.