power electronic based power and propulsion systems are used in a wide variety of applications including locomotives , hybrid electric vehicles , aircraft , spacecraft , and ships . in general , the power electronic loads in such systems have tightly regulated outputs which causes them to behave as constant power loads exhibiting negative input impedances in a small signal sense . such systems can be prone to negative impedance instability . the present invention mitigates negative impedance instability without the introduction of any passive or active devices into the system by providing nonlinear modulation of the power into the power electronic load .