Rotor position estimation in IPM motor drives based on PWM current harmonics

The paper investigates successfully the possibility of extracting the rotor position information of an Interior Permanent Motors from the PWM current harmonic contents. To this aim, a general description of PWM voltage harmonics is at first given. Current harmonics are then derived assuming an anisotropic rotor and pointing out the rotor position dependence. It is proved that rotor position information can be detected if single edge PWM is adopted. A speed and position estimation scheme is illustrated and the new rotor position estimation technique is then validated by simulations and preliminary experimental tests.