Design considerations for a stator side voltage regulated permanent magnet AC generator

Abstract

The application of permanent magnet generators in variable-speed applications is made difficult by the lack of a direct field control and the variation of the stator voltage with shaft speed and also with load. This paper presents the use of reactive power injection into the stator as a means of regulating the stator voltage. Design-oriented analysis of the machine stator current and reactive power requirements for this mode of operation leads to the conclusion that high machine saliency enables excellent terminal voltage regulation over a specified speed and load range while minimizing stator current requirements. It is shown that the incorporation of saliency into the permanent magnet generator can significantly reduce the size of the reactive current source and the stator current that is required to regulate the stator voltage during operation over a broad range of speeds and loads. Experimental results are presented to confirm the basic principles of this approach.

Regulation of permanent magnet generators using angle control of stator-connected voltage source inverters

“…It has also been shown that the use of an interior permanent magnet (IPM) synchronous machine with a high magnetic saliency can significantly reduce the weight, volume, and cost of the injection current source, making this approach more appealing for a variety of weight-and costsensitive applications [4].…”

Nonlinear Model Predictive Control of Permanent Magnet Synchronous Generators in DC Microgrids

“…Since the latter utilizes both d and q axis currents, when the same strategy as SPMSM is used for IPMSM, the reluctance torque is not optimally used and the generator/motor is operated at a lower power factor (increasing ac side losses). For example, in [2], [4], [6], [7], [9], [10], [16], [20], the q axis current is used to control the dc bus voltage (generator) and Most controllers for dc/ac and dc/dc converters employ a two loop strategy: inner current control and outer voltage or speed/torque control [12], [22], [23], and their stability analysis is typically presented using linearization techniques such as root locus [19]. This particular control structure owes its development to the nature of the physical system, composed of both fast and slow states.…”