Vpliv magnetnih nelinearnosti sinhronskega stroja s trajnimi magneti na izkoristek pogona z brezsenzorskim vodenjem : doktorska disertacija

slovenian

doktorska dela

2013

Univerza v Mariboru, Fakulteta za elektrotehniko računalništvo in informatiko

This Ph.D. thesis deals with the efficiency improvement of an electrical drive. It focuses on the efficiencies of inverter and electrical machine, which, in the given case, is a Permanent Magnet Synchronous Machine (PMSM). The efficiency of an electrical drive depends on the power losses in individual elements of the drive. The findings of performed analysis of drive's losses are used to select the most suitable solutions for efficiency improvements in individual drive elements and in the entire drive. Only those solutions that can be applied on the existing inverter and PMSM are considered, which means by the control realization and proper setting of inverter parameters. In the case of PMSM vector control realizations, the generation of the direct- and quadrature-axis reference currents has substantial impact on drive efficiency. In the reference currents generation the Maximum Torque Per Ampere (MTPA) characteristics are used. They provide the maximum torque per unit of current. In order to assure drive's maximum efficiency, the Maximum Efficiency (ME) characteristics are introduced in the reference currents generation. Since the analytical descriptions of the MTPA and ME characteristics contain some variable parameters that are difficult to be determined, the MTPA and ME characteristics are determined experimentally and given in the form of look-up tables. The PMSM vector control realization is modified by the inclusion of MTPA and ME characteristics applied for reference currents generation, which leads to the drive efficiency improvementthat is confirmed by measurements. The drive efficiency is further improved by the use of optimal modulation frequency and by the variable DC-busvoltage. The last one can substantially improve the efficiencies of variable speed drives operating at partial load and low speeds. All described solutions for efficiency improvement are applied to improve the efficiency of the PMSM sensorless control realization based on the active flux principle. The result is a mechanically robust and reliable sensorless drive realization,where the reference currents generation based on MTPA and ME characteristics improves the drive efficiency. The findings of this Ph.D. thesis are confirmed by experiments and measurements.

07.08.2023