Odtwarzanie napięcia stojana w falowniku trakcyjnym o niskiej częstotliwości przełączeń

The article describes concept of the vector modulator in the control system for the traction drives. The purpose of the proposed modulator is a connection of the well known vector control system with the inverters working with the low switching frequency. These systems are known to have strongly deformed signals of the currents and voltages with significant content of the higher harmonics. The modulator replaces a required voltage vector by the sequence of the well defined space vectors to be realized by a widely used PWM unit. The proper sequence of the vectors with precise PWM frequency leads to the low harmonic contents and the smallest possible deformation of the currents. The article presents the experimental results with the induction motor supplied by the traction inverter with switching frequency fixed at 400Hz.