New Adjacent Four-Vector Synthesis Principle-Based Phase Current Reconstruction for PMSMs

For the topology placing the shunt resistor between the upper bridge arms of two adjacent phases, the existing phase current reconstruction techniques (PCRTs) apply the active zerostate PWM (AZSPWM) to reconstruct phase currents. However, adopting four active voltage vectors to synthetize the reference voltage vector, AZSPWM introduces excessive phase current harmonics and only eliminates partial reconstruction dead zones (RDZ) in the low-modulation regions. To address these issues, this paper proposes a novel PCRT based on a new adjacent fourvector (A4V) synthesis principle. Firstly, this paper develops a right-angled triangle-based four-vector PWM (RAT-FVPWM) adopting zero voltage vectors to reduce current harmonics introduced by using AZSPWM. Then, a systematic analysis of the control degrees of freedom for RAT-FVPWM is given. Finally, a new PCRT based on the hybrid modulation with RAT-FVPWM is proposed to eliminate RDZ in the sector-boundary and lowmodulation regions. Through coordinated utilization of degrees of freedom and rational partitioning of space vector hexagon into 18 regions, the phase current harmonics are decreased with the proposed PCRT. Simulation and experimental results validate the effectiveness of the proposed method in this paper.