Based on analysis of the mathematic model for an induction machine excited by transient pulses

a method was proposed to obtain the rotor position information by superposing twice subtraction of current transient samples.The output of voltage-source inverter were taken as tested pulses to inject into the phase windings

and the current transient changes of the machine due to stator voltage test pulses were evaluated.Thus rotor information

from its standstill condition to high speed condition

were obtained and further identified by measuring the current transient slope resulting from the inverter PWM modulation.The disturbing of the interlock dead time and some voltage drops were studied by simulations assuming an ideal inverter and an ideal linear machine with no losses.The comparisons were made of the simulated waves of current transient change caused by either exciting pulses with dead time or the ones without dead time.It was found that the main influent of the dead time was a shift in the operating point of the machine.A compensation method was introduced to reduce disturbing harmonics.The feasibility and superiority of the proposed method was verified through the experimental research concerning an induction machine with parameters of 3 kW

380 V

and 50 Hz.