Optimization of air-cooled on-board battery chargers for electric vehicles using WBG devices

Inhalt:
By replacing the liquid cooling system of on-board battery chargers with a stand-alone air cooling system, the charger can be placed independently within the chassis. Air cooling improves reliability, reduces system complexity, and allows noiseless charging operation where natural convection cooling is applicable. To minimize power loss, wide bandgap devices and suitable circuit topologies were chosen. For a volumeoptimal heat sink design, analytical models were applied. Moreover, filter design and loss analysis were conducted analytically. Based on this, an optimization algorithm was developed to identify optimal circuit parameters resulting in minimum system volume. For a 3.7 kW charger, a maximum power density of 4.7 kW/dm3 was calculated for forced convection and 3.4 kW/dm3 for natural convection. An experimental validation shows the feasibility to realize the predicted component sizes.