Design of an optimal servo-controller for current control in a permanent magnet synchronous motor

The design of an optimal current controller for a permanent magnet synchronous motor is presented. Robust and simple current controllers that do not require the use of an added lagging compensator, are designed using the inverse linear quadratic (ILQ) design method. The ILQ design method is a strategy to find the optimal gains that is based on pole assignment without having to solve Riccati's equation. The basic ILQ technique is improved by the addition of an analytical equation that guarantees the optimality of the solutions. The optimum gains that minimise the settling time for step responses of the motor currents with no overshoot are obtained. The proposed procedure can be applied to any system with a single input and a single output and extends the conventional ILQ design method allowing its use in new areas.