Vector-Symmetry-Based PWM Phase Shift Compensation for Current Reconstruction Using a Single DC-Link Current Sensor

To reduce the complexity and cost of permanent magnet synchronous motor (PMSM) drive systems, a single DC link current sensor scheme with phase-shifting is often adopted for three-phase current reconstruction. However, traditional phase-shifting methods tend to introduce current distortion and increase harmonic content. To address this issue, this paper proposes an improved Vector Symmetry Phase Shifting (VSPS) criterion, which synchronously adjusts the three-phase trigger waveforms under symmetric constraints in space vector modulation (SVM). Furthermore, three phase-shifting methods are proposed based on the VSPS criterion, and their integration with an existing saturation handling scheme is analyzed in terms of the linear modulation range. The proposed methods feature the following characteristics: 1) they enhance the symmetry of pulse width modulation (PWM) signals; 2) they reduce residual voltage vector distortion under saturation handling for two of the three variants; 3) they require no modifications to the standard SVM architecture and introduce no additional switching operations. Simulation and experimental results demonstrate that the VSPS-based phase-shifting methods not only reduce the total harmonic distortion (THD) of the phase current but also extent the linear modulation range, as compared to conventional phase-shifting methods.