This paper deals with the torque control of m_s-phase synchronous machines where the first odd harmonics below m_s are injected. A new vectorial approach to describe the voltage and current limits is proposed. Starting from the transformed dynamic equations and using the voltage and current constraints, the optimal current references is obtained. It holds for an arbitrary number of star connected phases and an arbitrary shape of the rotor flux. Some simulation results for a 7-phase motor validate the proposed control law.