Vector controlled AC/AC converters with a minimum of energy storage

Increasing use of power electronic equipment causes an increasing harmonic load on the line. Regulations acknowledge this problem with limits for this harmonic load, expected to make it impossible to use directly connected diode rectifiers as in conventional frequency converters. An alternative solution is self-commutated rectifiers. In this paper a control strategy for a frequency converter with self-commutated line side is discussed, in order to minimize the necessary DC link energy storage. It is shown that synchronized modulation of both the line side and load side inverters together with load information feedforward from load side to line side current controllers has the potential to minimize the need of energy storage. Apart from minimized energy storage, higher power rating, bidirectional power flow and active filter capabilities are results of the topology discussed. Simulations and measurements are presented