In the present study, a drive scheme for IPMSM is proposed to obtain high dynamic performance and system efficiency with reduced computational cost. To achieve these objectives, a discontinuous modulation technique was used in the converter and an MTPA strategy was developed in the IPMSM. It is based on Lagrange interpolation with the Briot-Ruffini-Horner technique, which makes it possible to obtain interpolators with reduced interpolation error. Simulation results validated the accuracy and processing time of the obtained MTPA interpolation and a simulation based on a nonlinear machine model demonstrated the effectiveness of the proposed scheme.