Tesis doctoral de Carlos Ortega García
The control of ac machine drives is a continuously advancing subject satisfying increasing high performance applications demands. Induction motor (im) drives with cage-type machines has been the workhorses of industrial variable speed drives applications, including pumps and fans, paper and textile mills, electric vehicles, locomotive propulsion, wind generation systems, etc. In addition to performance requirements, energy saving aspects of variable speed drives is gaining attention nowadays. permanent magnet synchronous machines (pmsm) are becoming a very attractive alternative to im. Among other advantages, these type of machines offer higher efficiency, high power density and very fast dynamic performance. Pmsm, in particular in the low power range, are already widely used in industry and recently, the interest in their application is growing, particularly up to 100 kw. variable speed drives fed by voltage source inverters has been traditionally employed in industrial applications. In the past few years, matrix converters have emerged to become a close competitor to the conventional inverter. A matrix converter is an advanced circuit topology capable of converting ac-ac, providing generation of load voltage with arbitrary amplitude and frequency, bi-directional power flow, sinusoidal input/output waveforms, and operation under unity input power factor. Furthermore, since no inductive or capacitive elements are required, mc allows a very compact design. there are several methods to control ac machines, vector control methods being the most suitable for high performance demands. Among others, field oriented control and direct torque control are the most widely used. Although being one of the emerging control techniques for industrial applications, the direct torque control has some inherent drawbacks that are still being investigated by researchers. The work reported in this thesis is devoted to the investigation of direct torque control of pmsm drives fed by matrix converters. this work considers the replacement of the conventional voltage source inverter by a matrix converter. The features of matrix converters are exploited to reduce the inherent electromagnetic torque and stator flux ripples arising from the direct torque control driving a pmsm. A new direct torque control using small and large voltage vectors of matrix converters has been developed during the course of this work. the undesirable effects of the common mode voltage related with the utilization of the conventional voltage source inverter, like electromagnetic interferences and the machine early failures, are other issues with which this work is also concerned. A very simple algorithm to reduce the common mode voltage in direct torque control drives using matrix converters is developed and investigated in this work. the main limitation of all sensorless vector control schemes, based on the conventional fundamental frequency models or observers, is that they fail at very low speeds. The desirability to operate continuously at low or zero speed has led to another sensorless approaches where the saliency of the machine is tracked through some form of signal injection to obtain flux or position information. A new algorithm to inject a rotating vector in the frame when employing a direct torque control has been developed in this thesis.
Datos académicos de la tesis doctoral «Direct torque control of permanent magnet synchronous machines using matrix converters«
- Título de la tesis: Direct torque control of permanent magnet synchronous machines using matrix converters
- Autor: Carlos Ortega García
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 23/10/2008
Dirección y tribunal
- Director de la tesis
- Antoni Arias Pujol
- Tribunal
- Presidente del tribunal: josep Balcells sendra
- ramon Blasco gimenez (vocal)
- cyril Spiteri staines (vocal)
- greg Asher (vocal)