A Novel Predictive Control for an Active Front End Rectifier using Lyapunov Stability Criteria

A novel predictive current controller is proposed for a three-phase two-level active front end rectifier using virtual vector switching. Lyapunov stability criteria is applied to optimise the angle and magnitude of the virtual converter voltage vector to be applied at each sampling instant. The optimal virtual vector is then realised using suitable space vector modulation technique, thereby ensuring a constant switching frequency of operation of the converter. Since active front end converters are desired to operate at unity power factor, 60 degrees continual bus clamping space vector modulation is employed to reduce the switching losses. The proposed controller thus ensures optimum operation of the converter at a fixed switching frequency, similar to conventional model predictive controllers along with the reduction in line current ripple, improved line current quality, minimal switching losses and less computational burden on the controller. The efficacy of the proposed controller is investigated for a two level active front end rectifier and the simulation results are presented.