Armature reaction will cause a distortion of the distribution of the magnetic field in the air gap of the PM generator.
The d-axis component of armature reaction by the direction of permanent magnet axis will affect the strength of the primary magnetic field in the air gap (Fig.
It will reduce relatively the effect of armature reaction on the magnetic field in the air gap compared to conventional synchronous machines of traditional construction.
At analysing magnetic flux distribution of armature reaction for d-axis, the expression for resulting magnetic flux per one pole pitch [tau] in d-axis was obtained as follows:
sigma]d] is the magnetic flux coefficient of armature reaction for d-axis
The formulae for calculation of magnetic flux of armature reaction for q-axis can be expressed as
The d-axis component of armature reaction will cause reduction of magnetic flux density by about 12-15% in the teeth zone of the armature core at rated load currents.