Position sensorless and optimal torque control of reluctance and permanent magnet synchronous machines
Date
2009-03
Authors
De Kock, Hugo Werner
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
Keywords: position sensorless control, torque control, synchronous machines
The work in this thesis deals with energy e cient torque control and rotor position estimation
in the full speed range, for a family of synchronous machines that should be used more often
in the near future. This family consists of the permanent magnet synchronous machine
(PMSM), the reluctance synchronous machine (RSM), the interior-PMSM and the PMassisted-
RSM.
By designing and controlling these synchronous machines correctly, better performance and
higher energy e ciency can be expected compared to the performance and e ciency of an
industry standard induction machine. However, applications are limited to variable speed
drives (VSD) in a certain power range, e.g. below 100kW. With the growing concern and
necessity of a better utilization of energy, it is becoming standard to use electronically
controlled power converters between the electricity grid and electrical machines. Therefore,
there is a very large scope for the implementation of this synchronous machine technology.
For traction applications like electrical vehicles, the optimally controlled synchronous machine
technology has a very strong position. Very compact and robust synchronous machines
with a very high power density can be designed that may out-perform the induction machine
by far. However, one major requirement for most applications is position sensorless control,
i.e. rotor position estimation in the whole speed range.
To achieve energy e cient torque control, maximum torque per Ampere (MTPA) control
should be implemented. It is possible to achieve MTPA control at low speed, but above the
rated speed of the machine, eld weakening needs to be performed. The question is how to
implement MTPA and e ective eld weakening for any value of speed and DC bus voltage
and for any machine within this family of synchronous machines. In this thesis a method is
explained to achieve this goal using results from nite element (FE) analysis directly. The
scheme may be implemented within a very short period of time.
The contribution of this thesis is a general understanding of the problems at hand, with
an in-depth view into the mathematical representation of synchronous machines, a generic
method of energy e cient torque control and a thorough study of rotor position and speed
estimation methods.
Description
Thesis (PhD (Electric and Electronic Engineering))--University of Stellenbosch, 2009.
Keywords
Theses -- Electrical engineering, Theses -- Electronic engineering, Dissertations -- Electrical engineering, Dissertations -- Electronic engineering