Gain Scheduling Control Design for Active Front End for Power-Hardware-in-The-Loop Application: An LMI Approach

Abstract

The paper proposes a control design approach for the three-phase grid-side converter of a power amplifier inverter for Power-Hardware-In-the-Loop application. The main challenge for the controller design is to achieve a trade-off between the tight DC link voltage regulation and grid-side power quality objectives due to the established topology of the power amplifier and the associated ripple of the DC link voltage. To this end, a full-state feedback controller with a gain scheduling strategy is adopted to ensure fast control of the DC link voltage, while minimizing the negative impact of DC link voltage ripple on the AC output current. We formulate the problem of gain selection as a two-stage semidefinite programming problem, which allows using efficient convex program solvers. We also describe a bumpless transfer strategy to minimize any transients associated with control output discontinuities following gain transition. The paper demonstrates comprehensive validation of the designed controller, including offline simulations, Control-Hardware-In-the-Loop tests with an embedded controller, as well as experimental validation on a 2-kV 167-kVA module.