Optimised speed control in state space for PMSM direct drives

Nowadays, more and more applications use direct drive actuators. This leads to a more flexible structure represented by a two-mass model. Furthermore, the parameter variations create an oscillating system and need a new definition of controller synthesis to maintain unchanged performance. Firstly, a common pole placement is designed, followed by three methods based on linear quadratic optimisation: the first is optimised with a small number of parameter, the second takes the energy into account and the third combines this principle with the pole placement to achieve all the goals required by an industrial application. Finally, all controllers are compared with results obtained on an experimental test bench. All controllers reach the requirements but the last is quickly tuned and has positive results, thus providing an interesting method for engineers.