Synthesis of direct torque and rotor flux control algorithms by means of sliding-mode theory

This paper is an attempt to synthesize the direct torque and rotor flux control (DTRFC) algorithms of induction motor using sliding-mode theory. The choice of the sliding-mode theory has been motivated by the presence of switches in the voltage-source inverter (VSI). Changes in the state of the switches cause the variation in the topology of the controlled system. In addition, this theory offers a mathematical process that allows rigorous procedures of analysis and synthesis. The developed voltage vector is generated by two methods: direct control of the VSI (hysteresis VSI control), and indirect control of the VSI using space-vector modulation. In addition, taking into account the complementarity of the advantages of each VSI control algorithm, the high dynamic performance of the direct control and the smoothness of the indirect control, the idea of the dynamic reconfiguration of DTRFC algorithms is proposed.     

Extension of the DTC concept

The authors propose to extend the direct torque control (DTC) concept. This extension concerns voltage-vector generation. Based on this, it is possible to generate any voltage vector by the space-vector modulation method and apply DTC strategy at the same time. Experimental results are carried out to validate the proposed approach     

Modeling and control of a cascaded doubly-fed induction generator based on dynamical equivalent circuits

This paper deals with the control of an autonomous cascaded doubly-fed induction generator operating in a variable speed constant frequency mode. The proposed structure is a full stand-alone generating system dedicated to isolated grids in embedded systems or in small-scale renewable energy systems such as windmill and hydropower generators. The study is focused on the CDFIG. Its behavior against several design parameters (numbers of pole pairs and rotor interconnection) is recalled. A model, based on dynamical equivalent circuits, is also given for the design of the controller. Finally, the synthesized controller is validated by simulations and experimental results.     

FPGA-Based Current Controllers for AC Machine Drives—A Review

The aim of this paper is to present the interest of implementing digital controllers using field-programmable gate array (FPGA) components. To this purpose, a variety of current control techniques, which is applied to alternating current machine drives, is designed and implemented. They consist of on-off current controllers, proportional-integral current controller, and predictive current controller. The quality of the regulated current is significantly improved. It is mainly due to a very important reduction of the execution time delay. Indeed, in all described techniques, the execution time of the designed hardware architectures is only a few microseconds. This time reduction derives directly from the possibility offered by FPGAs to design very powerful dedicated architectures. Numerous experimental results are given in order to illustrate the efficiency of FPGA-based solutions to achieve high-performance control of electrical systems.