Comparing the indirect field-oriented-control with a scalar method

The indirect field-oriented (IFO) control and the slip-controlled (SC) method are considered. Their block diagrams and experimental results are analyzed and compared. It is shown that the block diagrams are similar. Their difference lies just in a feedforward block, called the phase regulator block, that gives the current phase to be supplied to the motor in an IFO controller. To perform comparative tests, both control techniques were implemented using the same hardware blocks. The torque time response, the frequency response of the speed-controlled induction motor drive, and the influence of the rotor electrical time constant for both control methods are analyzed based on experimental results. The main conclusion is that the implementation difficulties and cost of both control strategies are quite the same, although the IFO control method has a much better performance than the SC control method, as expected