H(s) resembles the transfer function of a negative feedback control system, where the forward path has a unity gain and the feedback is the impedance ratio. Thus, the stability can be analysed based on the impedance ratio, which is also known as the minor loop gain [23]. The Thevenin and Norton equivalents are interchangeable, and choosing Norton equivalent for source and Thevenin equivalent for load inverts the minor loop gain to be Zl (s)/Zs(s). As discussed in [24], the stability analysis can be performed similarly for Zl (s)/Zs(s) and Zs(s)/Zl (s), and the ratio should be chosen so that it has no right-half plane (RHP) poles.