Current phase control methods for permanent magnet synchronous motors

Three types of current phase control methods are examined for the interior magnet motor and the surface magnet motor: (1) the i _d=0 control method, (2) the cos φ=1 control method, and (3) the constant-flux-linkage control method. The control circuits for realizing these control methods were investigated and a drive test carried out. The most suitable current phase control method for the rotor geometry was examined by computer simulation and experimentation. It was found that in the i_d=0 control method, high-performance torque control can be obtained as the torque is proportional to the armature current. In the cos φ=1 control method, the torque per armature current is small and the torque characteristic is nonlinear. Therefore, high-performance torque control cannot be expected. The constant-flux-linkage control method is desirable for interior magnet motors as the torque characteristic is almost linear and the required inverter capacity is comparatively small