Search

The direct thrust control (DTC) has been utilized as a general formalism methodology for permanent-magnet linear synchronous motors (PMLSMs). The imposition control policies did not seem to handle the inherent flux linkage problems. This paper will try to propose a solution for the problems. This paper presents a genetic PI parameters generator and a new DTC policy for the motor control systems. Moreover, this paper also proposes a new switching table which can assist in selecting the optimum voltage vectors for the control system. The advantage of the proposed approach is that the clear presentation of the system behavior and readiness for implementation. Finally, some results of the simulation and the experiment both are met as expected. To the authors' knowledge, this is the first work that employs DTC to implement on a real-world PMLSM which is starting at arbitrary positions and can be allowed moving in the full route. Index Terms--Direct thrust control (DTC), flux linkage estimation, permanent-magnet linear synchronous motor (PMLSM).

A siphon-based algorithm for deadlock prevention of a type of Petri nets called [S.sup.3]pMR, which is a subclass of [S.sup.3]PG[R.sup.2], is presented in this correspondence. The proposed method is an iterative approach by adding two kinds of control places called ordinary control (OC) places and weighted control (WC) places to the original model to prevent siphons from being unmarked. An OC place with ordinary arcs, which optimally prevent a siphon from becoming unmarked, is employed whenever it is possible, and otherwise, the WC places that adopt a conservative policy of controlling the release of parts into the system are used. Furthermore, this algorithm is not only for the subclass Petri nets but also for [S.sup.3]PR, E[S.sup.3]pR, [S.sup.2]LSPR, and [S.sup.3]PG[R.sup.2] nets. The authors prove the liveness and reversibility of the controlled net, and hence establish the correctness of the deadlock prevention policy. Finally, numerical experiments indicate that the proposed policy appears to be more permissive than closely related approaches in the literature. Index Terms--Deadlock, manufacturing systems, Petri nets, siphon.