Comparison of not synchronized sawtooth carrier and synchronized triangular carrier phase current control for the VIENNA rectifier I

Integrated control circuits being available for the input current control of single-phase power factor correctors are frequently applied also for realizing a simple current control for each phase of a three-phase PWM rectifier system. There, the input currents are controlled independently although the three phases are mutually coupled, i.e., the sum of the phase currents is forced to zero for missing connections between the mains star point and the output voltage center point. However, ignoring of the coupling of the three phases results in increased amplitudes of harmonics with switching frequency and/or in a significantly higher ripple of the rectifier input current. This is shown in this paper by a detailed analysis of different current control concepts for a three-phase three-switch three-level boost-type PWM rectifier (VIENNA Rectifier I) with unity power factor. The theoretical considerations are verified by digital simulations and an experimental analysis of a laboratory prototype and are valid in general for three-phase boost-type voltage DC link PWM rectifier systems