Machine Parameter-Independent Maximum Torque Per Ampere Control for Dual Three-Phase PMSMs

This article proposes a novel dual dc injection-based maximum torque per ampere (MTPA) control algorithm for dual three-phase permanent magnet synchronous machines (PMSMs). The proposed analytical model takes magnetic saturation and temperature effects into account for achieving optimal current angle. In taking consideration of the two effects, a set of small currents are injected in the harmonic plane rather than the fundamental subspace, namely
DQ
₂
, which does not interfere with average torque output. In such a way, a novel torque model only involving the command currents and voltages is derived to avoid machine parameters. Furthermore, an MTPA indicator is constructed by the proposed torque to current model to seek the MTPA angle, in which the optimal current angle is found when the indicator magnitude reaches the maximum. In particular, the gradient descent algorithm is employed to ensure the adaptivity and robustness of MTPA control, which offers high real-time capability, low computational cost and low complexity. The experiments validate the proposed MTPA strategy under various load, speed and temperature conditions.