Wide-Speed Direct Torque and Flux Control for Interior PM Synchronous Motors Operating at Voltage and Current Limits

An Enhanced Finite-Settling-Step Direct Torque and Flux Control (FSS-DTFC) for IPMSM Drives

“…In this operation, the command voltage vector needs to be scaled back due to physical limits. For full utilization of the physical resources, both the voltage and current constraints should be considered when modifying the command voltage vector [5].…”

“…Recently, discrete-time versions of the DTFC, called the deadbeat-direct torque and flux control (DB-DTFC), have been introduced to achieve the fastest torque and flux response within operating limits [4], [5]. The DB-DTFCs apply the principle of deadbeat control to achieve a desired value in one inverter switching period.…”

“…Recently, a finite-settling-step DTFC (FSS-DTFC) method associated with the inverter voltage and current constraints for IPMSMs has been proposed [5], [6]. The FSS-DTFC is an exact counterpart of the DB-DTFC, in terms of the physical constraints, in discrete time.…”

“…Howeveer, it has one important caveat because it relies on the steady-state current limit (SSCL) [5]- [7]. Although a relatively simple calculation can be achieved when using the SSCL, the number of potential secondary upsets is increased, i.e.…”

“…Although a relatively simple calculation can be achieved when using the SSCL, the number of potential secondary upsets is increased, i.e. a more complicated voltage selection rule due to multiple solutions, add-on harmonic production [5] which is more significant at higher speeds, and an instantaneous over-current exceeding the inverter maximum current.…”