An effcient induction motor drive method with a regenerative power storage system driven by an optimal torque

When the motor speed is reduced by using a regenerative brake, the mechanical energy of rotation can be converted to the regenerative electric energy. In order to improve the efficiency of the motor drive systems, the regenerative power is charged and discharged by power storage systems (PSS). Moreover, optimal regenerative and acceleration torque of the motor should be discussed in order to maximize the regenerative electric energy and to minimize the required energy for acceleration. This paper presents an effective robust control method of a regenerative power storage system (PSS) and a design methodology of an optimal acceleration torque in order to achieve an efficient induction motor drive system. The PSS, treated in this paper, consists of an electrolytic capacitor and a bi-directional DC-DC chopper. At first, it will be shown that the PSS can be represented by a quite general second order differential equation. For this model, a robust control method will be proposed. Secondary, an optimal acceleration torque will be derived by means of variational method. The effectiveness of the proposed methods are illustrated by some simulations and experiments.