Analysis And Control Of V Style Interior Composite-Rotor Controllable-Flux PMSM

Permanent magnetic synchronous machine(PMSM) has perfect performance and wide application future. In the fields of digital control machine tool, robot and navigation, PMSM has applied value. Vlado Ostovic brought forward the idea of interior composite-rotor PMSM—memory motor at first. But there are disadvantages in structure and mechanical behavior. Using the different characters of NdFeB and AlNiCo, this paper introduces a new class of interior composite-rotor controllable-flux PMSM which has high power density, wide speed range and flux memory function-memory motor.This paper analysis the flux distribution characters by magnetic circuit calcution. To obtain ideal magnetic material structure, this paper analysed and calculated different structures and then proposed 6 poles V style structure. The radial-set magnets are NdFeB. The tangential-set magnets are AlNiCo. Applying a pulse of stator current id, the magnetizing intensity and direction of AlNiCo are controllable. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified. Or the flux created by NdFeB is partially bypassed by AlNiCo in the rotor. So the air-gap PM-flux is weakened. The dimension of permanent magnet and magnetic structure are demonstrated. When the q-axis larger magnetic resistance and smaller inductance are designed, the result of weakening-flux will be better. And the influence of armature reaction on air-gap PM-flux is weakened. In order to increase the q-axis magnetic resistance, hollow slots are specially set in each d-axis.This paper proposed the control strategy suit to the new class of machine. That is when the speed needs to be changed, In a fraction of period of current, applying a pulse of id with controllable amplitude and direction in three-phase stator windings induce magneto motive force of d-axis armature reaction. And the air-gap flux is reduced or enhanced. So the speed can be changed. Control strategies of i=iq and id=0 are adopted when needless to adjust speed in order to lower copper loss. The control system of PMSM is built taking DSP chip TMS320LF2407 as core device.