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Three-phase dc/dc converters have the superior characteristics including lower current rating of switches, the reduced output filter requirement, and effective utilization of transformers. To further reduce the voltage stress on switches, three-phase three level (TPTL) dc/dc converters have been investigated recently; however, numerous active powers switches result in a complicated configuration in the available topologies. Therefore, a novel TPTL dc/dc converter adopting a symmetrical duty cycle control is proposed in this paper. Compared with the available TPTL converters, the proposed converter has fewer switches and simpler configuration. The voltage stress on all switches can be reduced to the half of the input voltage. Meanwhile, the ripple frequency of output current can be increased significantly, resulting in a reduced filter requirement.
This paper proposes a sensorless control method for a surface-mounted Permanent-Magnet Synchronous Machine (PMSM) based on the stator parameters. The toque of the motor is indirectly controlled based on the stator voltage measurements and current measurements and also on knowledge of stator inductance and stator resistance. The rotor speed is also indirectly calculated and used for sensorless speed control. The use of sliding control (smc) technique method provides a straight forward solution for the control input. It is a dynamic control scheme which minimises error by comparing input and output values. It is a robust control scheme based on the concept of changing the structure of the controller in response to changing the state of the system in order to obtain desired output. Experimental results confirm good dynamical performance, even at low speeds.