Modern methods of motor drives control are ought to be high precision and quality. This quality is achieved through a rapid and accurate realization of given electromagnetic torque which is insensitive to inverter voltage changes. As a result of using such control methods, a whole system can be considered as an element on constant power for constant angular velocity of the rotor, which leads to occurrence of negative admittance in presence of voltage changes. When an inverter input filter has a high inductance value, negative admittance leads to the excitation of input filter voltage oscillations, whose amplitude often exceeds 50% of nominal voltage. Such a perturbations of inverter voltage can lead to unstable work of electric drive or to damaging one of the inverter elements. The article outlined a method for stabilizing an inverter voltage, through an additional admitance which compensates an unstable component of system. Theoretical considerations and practical algorithm are included. As confirmation of the high efficiency of the proposed algorithm, article contains computer simulation, tests and results.