From the discussion above, the accuracy of the current polar is of importance to the compensation results, thus some operations must be cautious. Firstly, the angle φ and compensated time must be calculated in each PWM period. If the angle φ cannot be determine in time, the dead-time compensation effectiveness will decrease. Fig. 2 displays the stator phase current in 25Hz, while the angle φ is updated each 5 PWM periods, and there is some distortion on the curve due to improper dead-time compensation.