Jan Melkebeek

Speed sensorless direct torque control of induction motors using an adaptive flux observer

The authors present a new sensorless induction motor drive. The drive uses an adaptive flux observer for speed estimation and the discrete-time direct torque control technique for torque and stator flux control. The adaptive flux observer uses a mechanical model to improve the behavior during speed transients. The estimated stator flux of the adaptive observer is used in the discrete-time direct torque control method to provide fast torque response combined with torque ripple free operation over the whole speed range. The sensorless drive system is capable of working from very low speed to high speed and exhibits good dynamic and steady state performance. The authors demonstrate the steady state and dynamic performance of the proposed sensorless drive using simulation and experimental results.

Small-Signal

As the performance of microcontrollers has increased rapidly during the last decade, there is a growing interest to replace the analog controllers in low power switching converters by more complicated and flexible digital control algorithms. Compared to high power converters, the control loop bandwidths for converters in the lower power range are generally much higher. Because of this, the dynamic properties of the uniformly-sampled pulse-width modulators (PWMs) used in low power applications become an important restriction to the maximum achievable bandwidth of the control loop. Though frequency- and Laplace-domain models for uniformly-sampled PWMs are very valuable as they improve the general perception of the dynamic behavior of these modulators, the direct discrete design of the digital compensator requires a

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-Domain Analysis of Digitally Controlled Converters

-domain model for the combination modulator and converter. For this purpose a new exact small-signal

Digitally controlled boost power-factor-correction converters operating in both continuous and discontinuous conduction mode

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Input-Current Distortion of CCM Boost PFC Converters Operated in DCM

-domain model is derived. In accordance with the zero-order-hold equivalent commonly used for “regular” digital control systems, this

Small-signal Laplace-domain analysis of uniformly-sampled pulse-width modulators

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Improved Natural Balancing With Modified Phase-Shifted PWM for Single-Leg Five-Level Flying-Capacitor Converters

-domain model gives rise to the development of a uniformly-sampled PWM equivalent of the converter. This

Reciprocity relations for the mutual inductances between orthogonal axis windings in saturated salient-pole machines

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Modeling of electromagnetic phenomena in soft magnetic materials under unidirectional time periodic flux excitations

-domain model is characterized by its capability to quantify the different dynamics of the converter for different modulators, its ease of use and its ability to predict the values of the control variables at the true sampling instants of the real system.