IPMSMs used for industrial applications generally require high efficiency operation in a certain operating point or area in addition to constant torque operation. In this research, the examined motor demands high efficiency operation at high speed and high torque area. In this case, the current phase angle is small and it is difficult to use reluctance torque effectively. Furthermore, concentrated winding structure has been adopted to cut manufacturing cost and to use limited space effectively. In general, IPMSMs using concentrated winding structure have a difficulty of generating reluctance torque from the perspective of getting #-axis armature reaction magnetic flux. In this paper, to enhance the efficiency of V-shaped IPMSM using concentrated winding structure at high speed and high torque area, the rotor structures which effectively use permanent magnet torque have been examined. Analysis result of 2D-FEA shows that the examined rotor structure, which arranges disproportional gap and large flux barrier on the #-axis magnetic flux path, can enhance the efficiency at high speed and high torque by suppressing the #-axis magnetic flux and by concentrating the field magnetic flux of PMs on the d-axis.