Abstract: Under the electromotive force (EMF) of ideal trapezoidal wave, when the current of ideal three-phase square wave is passed, although the brushless DC motor can produce a constant instantaneous torque, it cannot minimize the copper loss. Considering the EMF of non-ideal trapezoidal wave and the current of non-ideal square wave, large torque ripples will be generated. For this reason, a copper loss minimization and instantaneous torque control technology of brushless DC motor with phase EMF vector orientation was proposed. The mathematical model under the phase EMF vector-oriented d-q rotating coordinate system had the characteristic that the torque was only related to the current of q-axis winding and not related to the current of d-axis winding, which was the basis for realizing the constant instantaneous torque control of the brushless DC motor. In addition, the d-axis current required for copper loss minimization was theoretically calculated, and a brushless DC motor instantaneous torque control system that could minimize copper loss was constructed. The proposed control technology verified its feasibility and effectiveness through corresponding dsp control experiments.