On the space vector modulation and limiting algorithms for three-phase four-leg voltage source inverter in abc coordinates

This paper proposes two limiting algorithms for three-phase four-leg voltage source inverters to constrain the command vector inside the dodecahedron defined by the boundaries of the inverter linear operating range in abc coordinates. The first algorithm uses an inscribed ellipsoid on the dodecahedron, and the second one is based on the dodecahedron boundary planes. A detailed description, with the key points required for a digital implementation of space vector and limiting algorithms, is given. In addition, the output voltages controlled by means of MIMO controller in abc coordinates. This controller is designed using optimal discrete linear quadratic regulator technique, which ensures stability for the system. In order to provide smooth transitions among the different modes of operation, nonlinear MIMO anti-windup algorithm is proposed to dynamically update the controller variables. Finally, simulation and experimental results on a 15 kVA PWM inverter controlled by a DSP TMS320F241 are presented to validate the proposed algorithm and demonstrate the performance of the overall system.