| Abstract |
Large energy storage systems are used in many applications. If they are not in operation continuously, they will discharge themselves. To restart the operation, the supercapacitors should be pre-charged again to reach the nominal voltage range. Mostly, the capacitors are connected to a source via a DC/DC converter. For a fast reaction on load transients, fast-switching DC/DC converters are needed. Due to the high switching frequencies, soft switching is essential to keep the losses low. This is important for the normal operation but also for the pre-charging phase because pre-charging takes up to several minutes for large capacities. This work presents a zero-voltage switching (ZVS) analysis and extended-phase shift (EPS) modulation to reach ZVS switching for all semiconductors of the DC/DC converter during the complete pre-charge procedure. The analysis is done with a capacitance time-domain-based model and experimentally validated on a prototype. |
