Extension of Virtual-Signal-Injection-Based MTPA Control for Interior Permanent-Magnet Synchronous Machine Drives Into the Field-Weakening Region

This paper presents a field-weakening control scheme to expand the speed operating region of the recently reported virtual signal injection control (VSIC) method for interior permanent-magnet synchronous machine (IPMSM) drives. Because of voltage saturation, the VSIC for IPMSM drives is not effective in the field-weakening region. A new control scheme is developed to guarantee that the torque can be controlled with minimum current amplitude. The proposed method realizes fast dynamic response and efficient operation of IPMSM drives in both constant torque and field-weakening regions by controlling the d-axis current through virtual signal injection and detection of the voltage saturation. The proposed method can track maximum torque per ampere (MTPA) points in the constant torque region and voltage-constrained MTPA points in the field-weakening region accurately without prior knowledge of accurate machine parameters. The proposed control method is demonstrated by both simulations and experiments under various operating conditions on a prototype IPMSM drive system.