Implementation of AC servo controllers employing frequency-domain optimization techniques

The design and implementation of a permanent magnet synchronous motor drive based on H₂ and H_∞ optimal control theory are presented. A mathematical model of the drive is introduced. Based on appropriate assumptions, the model is reduced to a second-order, linear time-invariant system so that the H₂ and H_∞ optimization techniques are applicable. H₂ and H_∞ controllers are derived on the basis of the simplified model. A stability analysis is conducted, and stability regions based on controller tuning parameters and sampling periods are constructed. The relationship between closed-loop bandwidth and sampling period due to discretization effect is investigated. Implementation of the controllers and experimental results are described. A multiprocessor-based, fully digital control system is used to realize and experimentally verify the H₂ and H_∞ control algorithms. Controller performance is evaluated in terms of speed and position responses, and closed-loop and sensitivity frequency responses