Comparison of nonlinear and linear control schemes for independent stabilization of parallel multi-phase converters

Using a parallel three-phase boost converter consisting of two modules, we compare the performances of three nonlinear control schemes. The basic idea, however, can be extended to a system with N modules and other multi-phase converters. All of the control schemes are developed in a synchronous frame and each of the closed-loop power-converter modules operates asynchronously without any communication with the other module. The control schemes stabilize the currents on the dq axes and limit the zero-axis disturbance by preventing the flow of the pure-zero sequence current. One of the control schemes is developed purely in the discrete domain. It combines the space-vector modulation scheme with a variable-structure control, thereby keeping the switching frequency constant and achieving satisfactory factory dynamic performance. The performances of the other control schemes are also satisfactory.