Stability of induction motor drive controlled by current-source inverter

The stability of an induction motor driven by pulse width modulated current-source inverters (CSI) is considered. The effects of capacitors connected in parallel with the induction motor, to bypass the commutating energy, can not be assessed by conventional analysis methods. To overcome this limitation, a method based on a rigorous state-space analysis is presented and compared with the more usual approximate analysis by means of dominant roots of the system. The results confirm the feasibility of pulse width modulated CSIs and show that larger bypass capacitors cause oscillating unstable operations, even with constant V/f control