An Efficient Controller for SV-PWM VSI Based on the Multivariable Structure Function

In this paper a novel control strategy for pulse-widh modulated voltage source inverters (PWM VSI) is presented. It is based on a linear, diagonal, low order, minimum-phase, fixed, and stable multivariable controller. It is obtained via individual channel design (ICD), a new framework that allows analysis and synthesis of multivariable control systems by means of the multivariable structure function (MSF). Such controller generates the appropriate reference voltage signals for the power inverter via a space-vector PWM (SV-PWM), which in turn provides the voltage signals for the terminals of an induction motor. The theoretical principles behind this control strategy are summarised for completeness. The similarities and differences between some current loop controllers found in literature and the scheme here proposed are discussed. In order to show the ICD controller performance a digital simulation is included. Moreover, it is also shown through the MSF that the dynamical system structure is not sensible to rotor speed or parameter variations. Therefore, it is possible to design a fixed linear robust controller for the whole speed range. Such solution is feasible for engineering applications due to its simplicity and robustness.