Optimal LQI synthesis for PMSM driving mechanical load with inertia variation and elastic joint

In industrial world, direct drives are more and more used and rise up new control issues when parameter variations occur. New methods have been created, however, high cost computer and expert is often needed to implement them. In this paper, state feedback controller optimized by linear quadratic principle are shown up. These methods achieve cost requirement cause they provide lighter regulators with constant gain coefficients. Criterions must let the closed loop system stable and keep performances whatever the load inertia is. First method is using an iterative method using linear quadratic criterion with few parameters. The last blends traditional poles placement and linear quadratic principle to achieve a fast synthesis method with interesting results. Experimental results have been obtained taking into account internal current control and inverter limitation too.