An electric bus system has been operating in the downtown area of Chattanooga, Tennessee for more than four years. The buses use traditional hard-switched IGBT inverters driving special induction motors with a speed sensor (tachometer) and two embedded fluxsensing windings to provide rotor speed and flux information to the motor controller for implementation of high performance field oriented c...

This paper presents a predictive torque and flux control algorithm for the synchronous reluctance machine. The algorithm performs a voltage space phasor pre-selection, followed by the computation of the switching instants for the optimum switching space phasors, with the advantages of inherently constant switching frequency and time equidistant implementation on a DSP based system. The criteria...

Parallel to the highly successful Ericksen-Leslie hydrodynamic theory for the bulk behavior of nematic liquid crystals (NLCs), we derive a set of coupled hydrodynamic boundary conditions to describe the NLC dynamics near NLC-solid interfaces. In our boundary conditions, translational flux (flow slippage) and rotational flux (surface director relaxation) are coupled according to the Onsager vari...

In the present paper a simple sensorless spccd estimation scheme is presented , where the speed information is obtained from the motor phase current ripple. The scheme measures the stator current phasor deviation direction to determine the back emf vector position during inverter zero vector switching states. This measurcment of rotor flux position is done indirectly by computing the motor back...

One of the most important issues in power system restoration is overvoltages caused by transformer switching. These overvoltages might damage some equipment and delay power system restoration. This paper presents a radial basis function neural network (RBFNN) to study transformer switching overvoltages. To achieve good generalization capability for developed RBFNN, equivalent parameters of the ...

Direct torque control (DTC) of an induction motor fed by a voltage source inverter is a simple scheme that does not need long computation time and can be implanted without mechanical speed sensors and is insensitive to parameter variations. In principle, the motor terminal voltages and currents are sampled and used to estimate the motor flux and torque. Based on estimates of the flux position a...

AC drives are more predominant than dc drives. Ac drives require control of frequency, current and voltage for variable-speed applications. The difference between the traditional vector control and the DTC is that the DTC has no fixed switching pattern. The DTC switches the inverter according to the load needs. Though conventional DTC (CDTC) is simple, easy to implement generates substantial st...