Self-Sensing Control of Induction Machines based on an Additional Single-Axis Short-Circuited Rotor Winding

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With the aid of field-oriented control methods, induction machines (IM) can be employed to design highly dynamic drives of high Control quality when using the appropriate mechanical sensors. Compared to the conventional operation with sensors, sensorless or self-sensing Operation features a lot of advantages, such as saving of cost, volume and maintenance effort as well as operation under extreme environmentalconditions not permitting the use of mechanical sensors. The challenge is to ensure position and speed tracking over the entire speed and frequency range. Up to now, there exist no self-sensing control methods for IM which are applicable down to zero Stator frequency, requiring low magnetization with little losses especially at low torques, and which allow for rotor position estimation. The Focus of the research project is on investigating design methods for a self-sensing control over the entire speed range featuring the aforementioned aspects. The initial point is to investigate a self-sensing control method using the same observer structure for EMF-based and saliency-based estimation. To further improve the quality of self-sensing control, current oversampling and almost complete voltage error compensation of the inverter shall be employed. Another goal is to develop a novel rotor design for IM to increase saliency, in order to facilitate particularly the operation of IM up to zero Stator frequency even at low magnetization. The basic idea of a unified observer structure and a modified rotor design has already been successfully investigated in preliminary work of the applicants done on permanent magnet synchronous machines (PMSM). The major issue of this proposal is to find out if and how these approaches can also be apploed to IM and in how far it is possible to improve self-sensing control of IM. Apart from transferring the aforementioned methods to IM, a method shall be developed to design the rotor with an additional coil with the aim to increase the rotor position-dependent saliency of IM without considerably deteriorating torque and torque ripple as well as efficiency. The aditional coil has to b e considered when modelling the machine for the control. Based on the enhanced model, a self-sensing control shall be investigated, tracking the rotor position by use of the newly applied saliency. Performance and limitations of the novel self-sensing control shall be evaluated in a final step.