| Abstract |
Deadbeat-direct torque and flux control (DB-DTFC) is a powerful control law for drives which allowsfor choosing the flux linkage at every switching period without affecting the torque. This independentmanipulation of torque and losses, i.e. flux linkage, allows for new capabilities such as dynamic lossminimization at every switching instant, signal injection without any additional torque ripple forparameter estimation or self-sensing, as well as closed-loop torque control with minimal parametersensitivity. Moreover, since DB-DTFC uses an inverse model solution based on flux linkages, itinherently utilizes the full inverter Volt-sec. hexagon without changing the control law at the inverterlimits. While these features cannot be achieved with conventional current vector control (CVC), thispaper explains how to increase the capability of drives by flexibly moving between CVC, and DB-DTFCto take advantage of their best properties. The focus of this paper is to enable seamless and dynamictransitions between the controls even under parameter uncertainties. While switching betweencontrollers can add additional features, the switching transients are undesirable. In order to makeswitching between controllers more attractive, this paper focuses on making the switching transient assmooth as possible and shows how to shape the transient so it becomes acceptable for the application.The key issue here is that different controllers have different parameter sensitivities, so when theparameters are not precisely estimated, the controller will need to switch from one trajectory to the other. Finally, this paper discusses potential use cases for this technology. In particular, a comparison of the operation at the voltage and current limits for DB-DTFC and CVC is shown, where some controllertrade-offs become very obvious and control switching becomes an attractive solution. The discussion inthis paper is supported by simulation and experimental results on an IPMSM, which are in goodagreement with each other and the underlying concepts. |
