Abstract
Superconducting (SC) synchronous generators are
proposed as a promising candidate for 10–20-MW direct-drive
wind turbines because they can have low weights and small sizes.
A common way of designing an SC machine is to use SC wires
with high current-carrying capability in the dc field winding and
the ac armature winding is made with copper conductors. In such
generators, the dc field winding is exposed to ac magnetic field
ripples due to space harmonics from the armature. In generator
design phases, the ac loss caused by these ripple fields needs to be
evaluated to avoid local overheating and an excessive cooling budget.
To determine the applicability of different design solutions in
terms of ac losses, this paper estimates the ac loss level of 10-MW
wind generator designs employing a MgB2 SC field winding.
The effects on ac losses are compared between nonmagnetic and
ferromagnetic teeth with different numbers of slots per pole per
phase. The necessity of an electromagnetic shield is then discussed
based on the obtained loss levels. The results show that the total
ac loss is so small that ferromagnetic teeth can be applied in the
generator design without using an electromagnetic shield.
proposed as a promising candidate for 10–20-MW direct-drive
wind turbines because they can have low weights and small sizes.
A common way of designing an SC machine is to use SC wires
with high current-carrying capability in the dc field winding and
the ac armature winding is made with copper conductors. In such
generators, the dc field winding is exposed to ac magnetic field
ripples due to space harmonics from the armature. In generator
design phases, the ac loss caused by these ripple fields needs to be
evaluated to avoid local overheating and an excessive cooling budget.
To determine the applicability of different design solutions in
terms of ac losses, this paper estimates the ac loss level of 10-MW
wind generator designs employing a MgB2 SC field winding.
The effects on ac losses are compared between nonmagnetic and
ferromagnetic teeth with different numbers of slots per pole per
phase. The necessity of an electromagnetic shield is then discussed
based on the obtained loss levels. The results show that the total
ac loss is so small that ferromagnetic teeth can be applied in the
generator design without using an electromagnetic shield.
