Vector control of cage induction motors: a physical insight

Understanding the ‘inside workings’ of the cage induction motor is helpful for electrical machines engineers in stripping away much of the mystique surrounding vector control. Attention is focused on how the rotor currents and flux linkages behave, and in particular on what must be done to the stator currents to achieve sudden step changes in torque. These questions are answered in a way which prompts a clear physical understanding of both the steady-state and transient behaviour. It turns out that the conditions are very simple, and that they can be quantified in terms of only two parameters, i.e. slip frequency and rotor time constant.