Energy efficiency is a major concern regarding the application of electrical actuators in the automotive industry. Online Maximum Torque per Ampere (MTPA) is an optimal strategy for the torque control of IPMSM at base speed, since copper losses are minimized. Current methods present various disadvantages, e.g. torque ripple, high measurement effort, heavy assumptions and convergence issues. This paper presents an algorithm to calculate MTPA set point online using known machine parameters. The convergence of the proposed solution is guaranteed and its feasibility and performance are demonstrated through simulation and experiments.