Operation analysis of a frequency converter with control realized in LabView

The paper presents a three-phase transistor bridge IGBT, controlled by a circuit made in LabView. The signal is collected from the parallel port, through a galvanic separation circuit made with optocouplers. The command sequence consists of three simultaneous pulses for three transistors, cyclic repeated to obtain the three-phase system of output voltages. The impulses are followed by a rest period before the next command sequence, to avoid the conduction of two transistors on the same branch. The signal output from the parallel port is amplified in current, for a firmer control of the optocouplers, and hence of the transistors IGBT, which are equipped with surge protection circuits.