| Abstract |
The paper reviews the general relations of vector PWM on the basis of conventional, polar
notation of the space vector. Vector amplitude and position is used, in this case, to compute vector
on-duration and commutation delays for the inverter. Two other notations are proposed in the paper:
on the basis of stationary ab co-ordinates and in abc frame. Very simple relations are obtained for
vector on-duration when using abc frame. Commutation delays can be calculated directly from abc
phase voltages of the machine. It is shown in the paper that space vector PWM is equivalent to the
carrier PWM, with modulating signal composed of a sinus and triple harmonic in the form very close
to a triangle. Overmodulation strategy based on the correction of commutation delays. is presented.
Gate pulse minimum time is always under control. Real position and amplitude of space vector in the
overmodulation are presented. |
