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 _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 _dc) becomes almost insensitive to the load variations. As a result, the level of v _dc could be stabilized with a small C _o. Without any considerations of the RMS current stress on the C _o, a calculation method of a minimum dc-link capacitor C _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.