Improving control of three=phase pulse inverter - changing over inverter switches according to current-tolerance band regulating method

摘要

The regulating deviations of the phase currents are determined by phase comparators, and upon reaching or overstepping specified tolerance bands for the phase currents, a set of controls is brought into effect. The switches are changed over so that respectively, upon exceeding a positive tolerance limit by a current regulating deviation of a phase, this phase is changed over to plus potential of the intermediate circuit voltage (on "1") and, upon exceeding the negative tolerance limit, to minus potential of the intermediate circuit voltage (on "0"). In the operating position "free-running" of the switching positions (000 and 111), upon reaching or overstepping a tolerance limit of the tolerance band of a determined phase, the two other phases are changed over, if one determined phase lies already at the correct potential of the intermediate circuit voltage for a correction so that a correcting change-over is not possible there. USE/ADVANTAGE - Preventing overstepping of current peaks during free running phases. Due to quick reaction, current regulating deviations are kept small.