Design considerations for the brushless doubly‐fed (induction) machine

Abstract

5A design procedure for the Brushless Doubly Fed machine is based on equations derived from a simplified equivalent circuit. 6The method allows the many variables in the design of this machine to be handled in straightforward way. Relationships are 7 given for the division of slot area between the two stator windings and for the design of the magnetic circuit. The design method 8 is applied to a frame size 180 machine. In particular, calculated values for flux densities in the machine have been verified by 9 time stepping finite element analysis for actual operating conditions. The approach outlined can also be used as part of a design 10 optimization routine.

Influence of Pole-Pair Combinations on the Characteristics of the Brushless Doubly Fed Induction Generator

“…Both the total pole-pair count and the split between the windings affect machine performance. Direct coupling between the two stator windings must be avoided and this can be achieved by applying the rules given in [18]. In some cases, several pole number combinations are possible and there is the choice of giving the higher or lower pole number to the PW.…”

“…An expression for the power rating of the brushless DFIG, calculated from the equivalent circuit model, was derived in [1]. This expression was based on the quadrature sum (B quad ) of the two fields in the machine but an alternative approach taking a more conservative view of the maximum allowable fields was developed in [18] based on the simple sum of the fields. Both relationships are given in A.…”

“…The PW power factor is set to 0.95 lagging, determining the CW voltage and the balance between B 1 and B 2 is changed by varying number of turns. The total flux density, B sum , is 0.7 T and peak flux densities in the rotor tooth and back-iron is limited to 1.5 T. All equivalent circuit parameters, including leakage inductances, are recalculated for each new design using the software described in [18]. The total stator electric loading is kept at 5.7 A/mm.…”

“…To investigate the effect, brushless DFIGs were designed with the same overall rotor dimensions, starting from the wellcharacterized 250 kW D400 frame size machine [15], for different pole numbers using the design methodology reported in [18]. The stator windings were configured to use the same number of stator slots and the rotor slots are chosen to give enough conductor area for the stator electrical loading to be balanced, with the same current density in the rotor conductors as the previous section.…”

Rotor optimisation design and performance comparison of BDFG for wind power generation

“…Unlike the traditional generators, there are two sets of windings with a different pole-pair number in the same stator, i.e. PW and control winding (CW) [11][12][13]. There is basically no literature to describe whether the CW should be few-pole winding or multi-pole winding, therefore, that needs to be researched further.…”