Abstract: Because of high working frequency, the output filter inductor of inverter power supply is usually about tens of microhenry, and the time constant is very small. In order to keep the system stable, integral circuit is usually used in feed back loop. Under this condition, when the disturbance occurs, there will be about 1ms before the system comes to stability, which is much longer than the inherent time constant of the system. A new kind of nonlinear synthesis control method is proposed. When the error between the input and the output is bigger than a threshold value, a nonlinear control method is used to change the width of working pulse of inverter, so the dynamic characteristic of inverter is enhanced greatly. Because the working pulse is symmetry, the transformer will work safely even the pulse width changes dramatically. The experiment indicates that nonlinear control method enhances the dynamical characteristic of inverter power supply greatly, which is very important to the waveform controlled inverter welding machine and pulse MIG welding machine.

Key words: Dynamic characteristic, Inverter power supply, Nonlinear control