Torque calculations of current-source induction machines using the 1-2-0 coordinate system

The authors extend the use of the classical induction motor equations obtained through the 1-2-0 coordinate system to cover situations with nonsinusoidal, chopped current sources. Detailed analysis is demonstrated through the widely used six-pulse, current-source-inverter-fed induction machines. The derivations of two different types of analytical torque equation (time-domain and frequency-domain series equations) are given. Their results are compared with each other and with results obtained from extensive air-gap and shaft torque measurements. The only difference in results between the frequency- and time-domain methods is that the voltage pulse corresponding to the switching is not included in the time-domain method; however, a voltage spike, as indicated by the frequency-domain-series method, would be expected at each switching point because of the rapid change of flux linkage. Test results agree with calculated results