Pseudo-vector control - An alternative approach for brushless DC motor drives

This paper provides an alternative approach called “Pseudo-Vector Control” (PVC) to reduce torque ripple in Square-wave PM Motors (BLDC motor). Instead of conventional square-wave form, the method uses the principle of vector control to optimally design the wave-form of reference current in such a way that the torque ripple is minimal. The currents are however still regulated in phase current control manner. The proposed PVC has 2 majors advantages: a) the torque ripple is greatly reduced, and b) the flux weakening for constant-power high-speed mode can be achieved by injecting a negative d-axis current into the control system, just like for the case of PM Synchronous Motors (sine type machines).