Electromagnetic Considerations in the Design of Doubly-Fed Reluctance Generators for use in Wind Turbines

Abstract

This paper reviews some of the electromagnetic design issues in a doubly-fed reluctance machine. This is a novel machine that is still under early-stage development. The control has been studied previously in several papers however the electromagnet design of this machine is now being studied with the key issue being whether to use an axially-laminated rotor or a radially-laminated rotor. This is discussed in the paper.

On the Possibilities of Using a Brushless Doubly-Fed Reluctance Generator in a 2 MW Wind Turbine

“…The machine was heavily loaded to check to see if there was any additional harmonic cross coupling. This was found to be a problem in the 2/6 machine in [1] and [2]. The cross-coupling is very important for correct operation.…”

“…However, as the speed reduces, say to 750 rpm, then the control winding frequency reduces to 25 Hz and now the control winding can only contribute half of the maximum power of the power winding because of the frequency terms in (2). The phasor diagrams are given in Fig.…”

“…The frequency in both windings is 50 Hz at this speed and equation (2) suggests that for maximum power at these currents then each winding contributes about the same power. In Fig.…”

“…A recent paper [1] assessed the iron losses generated in the axially-laminated machine and debated whether the correct option should be to use a radially-laminated rotor to reduce the rotor losses. This was expanded upon in [2]. The control of these machines has already been studies extensively [3]- [7].…”

Two converter based operation of a brushless doubly fed reluctance machine

“…But the majority of the published literature, e.g. [11]- [13], analyzes existing designs, rather than giving others clues regarding commercially viable BDFRM designs. Unlike synchronous reluctance machines, there is not much published information about appropriate design of radially laminated rotors for a BDFRM.…”