“…7. It is the most widely studied UPQC system configuration [12]- [15], [17]- [20], [22], [24], [26], [29], [32]- [34], [36], [38], [39], [42], [44]- [50], [52], [54], [56], [59]- [61], [63], [65], [67], [68], [71], [72], [74], [75], [80], [84], [87], [91], [92], [94]- [100], [103], [109], [112], [113], [115], [117], [119], [120], [124], [127], [131]- [139], [141], [143], …”