Design criteria for a synchronous active front-end in high power applications

In high power applications the problem of ac/dc conversion by four quadrants boost converters, named active front-end (AFE), is critical. Design criteria of these kinds of converters have to consider some aspects like: maximum switching frequency of inverters devices, harmonic currents circulating in the transformers, voltage notches at point of common couple (PCC) and the correct behavior of the AFE as current source. The currents absorbed by such a device are affected by a switching ripple whose characteristics are related to the electrical parameters of the boost converter. In high power handling, where the switching frequency is low, the ripple on line currents can be very dangerous and it produces notches in the node voltages which may cause several problems. The authors propose an innovative parallel system, called synchronous active front-end (SAFE) that well satisfies the trade-off between high dynamic performances and minimum harmonic noise. Moreover, the design criteria for a SAFE, are presented