Analytical modelling of an induction motor fed by a four‐switch PWM VSI

This paper presents analytical and experimental results that quantify the performance of an induction motor fed by a space‐vector pulse width modulated four‐switch (B4) voltage source inverter. First, as voltage vectors in the inverter form unsymmetrical sequences, the discrete Fourier transform is used to express the voltage vectors in symmetrical form. Second, by using a mixed p‐z approach for every voltage vector sequence, we can derive a closed‐form solution, including steady‐state and transient components of the motor currents. From the motor currents, we can derive an analytical equation for the electromagnetic torque. Both the steady‐state and transient components of the motor currents are determined in a simple and lucid analytical form, which avoids involved matrix inversion as well as exponentiation. The theoretical considerations are verified on an experimental unit.