| Abstract |
The presented work treats the modelling and the control of variable frequency converters. The modelling of these converters is rather delicate because of their variable framework. The variation of their states implies a global non-linear behaviour with respect to the state (output current and voltage) and to the entry (frequency). Thus we linearise the discrete model of the converter. For the analog control, a V.C.O. is needed. The behaviour of this one being non-linear at low frequencies, we propose a precise modelling of this component. To make nil the static error and to do the poles placement, we suggest an analog state feedback control with integrator. Associating to the model of the V.C.O., the converter one and the controller one we can build the closed loop transfer function and study the evolution of the poles locus, parametered by the parameters of the controller. In our case we have three degrees of freedom and we can impose the desired behaviour by mean of the resolution of a non-linear equations system. |
