Application of SMC with I/O feedback linearization to the control of the cascade controlled-rectifier/inverter-motor drive system with small dc-link capacitor

The necessity of the compactness of the converters in many applications imposes the reduction of the size of their different components when it is possible. In this paper, a control method allowing the use of a small size dc-link capacitor ([C.sub.o]) for the cascade of voltage controlled-rectifier/inverter-motor drive system is proposed. This is achieved by adding the power balance equation in the system's model and the application of an exact I/O feedback linearization technique in a way that the rectifier controller compensates any sudden change in the inverter load, which is here an induction motor. Since the exact I/O feedback linearization technique is sensitive to the uncertainties over system parameters, a robust control strategy based on sliding mode controller (SMC) is proposed. By this approach, the dc-link voltage ([v.sub.dc]) becomes almost insensitive to the load variations. As a result, the level of [v.sub.dc] could be stabilized with a small [C.sub.o]. Without any considerations of the RMS current stress on the [C.sub.o], a calculation method of a minimum dc-link capacitor [C.sub.o](min) based on its storage energy is proposed. All the investigations are shown by computer simulations and the performance of controlled system is verified by experimentation results. Index Terms--Controlled rectifier, induction motor, I/O linearization technique, sliding mode control, small dc-Link capacitor.