Predictive Current Control for Six-Phase PMSM Motor With Multi-Step Synthesis Based Virtual Vectors

Abstract

The concept of virtual vector has been a standard practice for the multiphase machine drives. However, simply adopting the fixed or adjustable duty-ratio virtual vectors fails to mitigate the current tracking error in the fundamental plane satisfactorily. To that end, this paper proposes a new model predictive control (MPC) method for a six-phase permanent magnet synchronous motor (PMSM) using multi-step synthesis based virtual vectors to regulate two planes simultaneously. The virtual vectors are formed through a two-step synthesis process. First, two groups of real vectors are used to synthesize 12 elementary virtual vectors to nullify the harmonic currents in the secondary plane. Subsequently, the 12 elementary virtual vectors are employed to further form other 60 composite virtual vectors to enhance the current tracking in the fundamental plane. For the sake of easy practical implementation, the pulse width modulation (PWM) switching sequence of all virtual vectors are analyzed to ensure that they present standard PWM switching sequence. The proposed multi-step synthesized composite virtual vectors can suppress the harmonic currents in the secondary plane and reduce the current tracking error in the primary plane simultaneously. Experimentations are conducted to verify the effectiveness of the proposed method.