Summary This study presents classical direct torque control (DTC) performance of line‐start permanent magnet synchronous motor (LSPMSM). An LSPMSM is designed based on an actual IM with finite element analysis. To present an in‐depth analysis, a comparison of a simple classical DTC performance of a three‐phase four‐pole LSPMSM and its equal induction motor (IM) in different conditions is provided. In addition, to evaluate the effectiveness of this method, simulation results from matlab/Simulink software are presented for both line‐starting and adjustable speed drive applications under the same conditions. Furthermore, both nominal voltage and voltage sag conditions are simulated for the aforementioned situations, and it shows that on one hand, the starting and synchronization process of LSPMSM often encounter problems for voltage sag conditions. On the other hand, a better transient and steady‐state response of an LSPMSM drive is obtained rather than that of IM, especially for voltage sag conditions. Copyright © 2014 John Wiley & Sons, Ltd.

SUMMARY This paper proposes a modified switching strategy for hybrid flow controller (HFC) as a power flow controller. The current strategies for HFC are suitable only for specific situations and generally are not applicable. The modified strategy is implemented by using the logical operators as a classical controller. Simulation results on two situations, representing all the possible states of the HFC, verify its performance. The fluctuations of the transferred active power caused by switching the HFC might have an adverse effect on the decision of the controller as well as the stability of the system. To mitigate the fluctuations, a fuzzy logic controller is designed, and also a comparison with the classical controller is provided. Copyright © 2013 John Wiley & Sons, Ltd.

An improved configuration of the hybrid flow controller (HFC) is introduced to continuously adjust the power flow. In this configuration, a thyristor-controlled series capacitance (TCSC) is added to the conventional HFC to provide continuous variation in the HFC reactance. Moreover, simple closed-loop control methods are designed by considering all the practical constraints of TCSC for this improved HFC (IHFC) and another hybrid arrangement, which is called hybrid power flow controller. Furthermore, to compare and highlight features of the IHFC, simulation results of the designed controllers are carried out in different operating conditions and disturbances. This study also provides a quantitative comparison of various hybrid flexible AC transmission system devices.

Summary In this study, a Z‐source alternating current‐to‐alternating current (AC–AC) converter with a specific topology, which can provide both buck and boost modes, is investigated. This converter, which can be implemented easily, utilizes only two switches with complemented commands. A comparison between the Z‐source AC–AC converter and a conventional thyristor voltage controlled one is presented here, and it shows that in the most areas, the Z‐source converter provides a faster response and lower total harmonic distortion of the output currents than the conventional one. Moreover, the Z‐source converter is also extended to the multiphase systems. In addition, a new arrangement of this converter is proposed here to remove the isolated single‐phase sources. Furthermore, an open‐loop method is proposed for soft‐starting applications. Finally, a closed‐loop control system is also suggested for a three‐phase Z‐source converter to soft start and control the speed of an induction motor. Computer simulations show the validity and effectiveness of the proposed schemes. Copyright © 2014 John Wiley & Sons, Ltd.

-This paper attempts to design and present a comparison of classical Direct Torque Flux Control (DTFC) for Line-Start Permanent Magnet Synchronous Motor (LSPMSM) and its equal Permanent Magnet Synchronous Motor (PMSM). In order to present an in-depth analysis, both motors for DTFC Voltage Source Inverter (VSI)-fed in the same situations of different conditions are simulated and tested. The advantages of the proposed method for LSPMSM over the PMSM are discussed and analyzed.