Ali Rabiei

Field-oriented control of a PMSM drive system using the dSPACE controller

Field-oriented control (FOC) of the permanent magnet synchronous motor (PMSM) is one of the widely used scheme in drive system application. Moreover, in some high performance applications, the rotor position information is needed that can be measured by a resolver for example. A drive system is designed and explained based on the FOC of a PMSM using the dSPACE controller. A resolver sensor is used for the position measurement in the system. Simulation and practical implementation results are presented to verify the proper operation of the drive system that is a speed controller in this case.

Comparative Study of a Multi-MW High-Power Density DC Transformer With an Optimized High-Frequency Magnetics in All-DC Offshore Wind Farm

In this paper, the design of a 1/30 kV, 10 MW modular isolated dc-dc converter is presented. The design and optimization of a high-frequency transformer as the key part of such a converter is addressed. Efficiency curves for different semiconductors and frequencies are presented in order to find an optimum frequency-enabling adequate transformer volume reduction with a suitable compromise with the converter efficiency. It was found that for this voltage level and size, it is no point to go above 6 kHz from the transformer perspective since the isolation requirement that leads to that the size is not reduced much more for even higher frequencies. At 5 kHz, the efficiency of the transformer having a nanocrystalline core reached 99.7% while the power density was about 22 kW/l. For the entire dc-dc converter, an efficiency of 98.5% was reached at 5 kHz switching frequency using SiC metal-oxide semiconductor field-effect transistors as switching elements while the efficiency when using insulated-gate bipolar transistors reached 97.2% at the same frequency.

Design considerations and laboratory testing of power circuits for parallel operation of silicon carbide MOSFETs

In this paper, the impact of using parallel SiC MOSFETs as the switching device is investigated. Measurement considerations for a double pulse test are discussed, and the influence of the load inductor characteristic and the voltage measurement technique on the measurement results is demonstrated. It is shown that the inductor load can produce high frequency oscillations of up to 10 % of the load current in the switching current, which can wrongly be associated with the switching device. It is also shown that the standard earth connection of passive voltage probes can induce an extra stray inductance in the measurement loop, which can lead to a measurement of an extra overvoltage of up to 50 V, which is not due to the actual switching. Moreover, the dependency of turn-on and turn-off losses on the load current and the dc-link voltage is presented. It is shown that doubling the load current would increase the switching losses more than the double amount. Therefore, use of two parallel MOSFETs instead of a single one would decrease the total switching losses for a given load current. On the other hand, the parallel configuration is shown to have a higher overvoltage than one single MOSFET for a similar load current. This, however, can be reduced by a higher gate resistance which will eventually keep the total switching loss of parallel configuration equal to the single MOSFET configuration for a given load current. Finally, it is also shown that switching losses can be greatly decreased by decreasing the gate resistance, but this leads to a higher overvoltage on the device. Therefore, the final choice for design is a compromise between the switching losses and the overvoltage.

Analytical prediction of switching losses in MOSFETs for variable drain-source voltage and current applications

This paper presents an analytical modeling of a MOSFET during switching operation, aimed at determining the switching losses. Moreover it compares the theoretical results with experimental data. The switching losses are calculated for different DC link voltages and load currents. The stray inductances and capacitances of the MOSFET were considered in the modeling. Besides the parasitic inductance in the circuit was calculated from the measurement and was applied in the loss modeling. It is shown that the switching waveforms obtained from the measurement are in agreement with the simulation results. However, due to the limitations of the drive circuit, the driver circuit output gate signal registered in the measurements had to be used in the simulations.

Switched reluctance motor in electric or hybrid vehicle applications: A status review

Drive systems based on a switched reluctance motor (SRM) are important alternatives in traction applications because of the motor simple and robust structure without using rare-earth permanent magnets. In this paper, different aspects of the SRM-based drive systems for the vehicle traction are presented and reviewed. Motor design and comparison with the permanent magnet motors, power electronics, simulation, control, and thermal design of the drive are explained and discussed.