A comparative overview of indirect field oriented control (IFOC) and deadbeat-direct torque and flux control (DB-DTFC) for AC motor drives

Abstract

Indirect field oriented control (IFOC) has become a widely adopted solution for AC motor drives. Standard IFOC controls torque and rotor flux linkage via q- and d- axis current. Alternatively, deadbeat-direct torque and flux control (DB-DTFC) has emerged as a promising motor control strategy for the future, which manipulates Volt-sec. vector directly. Air-gap torque and stator flux linkage are decoupled and independently controlled over each switching period. Stator flux linkage is used as a separated degree-of-freedom to manipulate losses dynamically without compromising torque dynamics and torque ripple. In voltage-limited operations, direct selection of Volt-sec. allows DB-DTFC to fully utilize the dc bus voltage and produce fast torque. A single control law is used over a wide speed range. This paper aims to provide a comparative overview of the two motor controls regarding their sensitivity to parameters, current- and voltage-limited operation, loss manipulation, and torque ripple during signal injection. Based on the comparison, the ultimate objective is to demonstrate the opportunities and remaining challenges in DB-DTFC.