One-cycle Control of induction machine traction drive for high speed railway part II: Square wave modulation region

The configuration of a single-phase AC-DC converter plus a three-phase DC-AC inverter traction system has been widely applied in high speed railway electrical drive systems. If the LC filter is not adopted in the DC-link, the DC-link voltage fluctuation may beat with the motor electric frequency, which could cause an increase in power loss, torque pulsation and audible noise. This paper aims to reduce the beat effect of DC-link voltage fluctuation in the traction drive system, Firstly, the harmonic spectra and beat phenomena are analyzed when square wave modulation is adopted in the high speed region. Secondly, a new extension of One-cycle Control (OCC) is proposed for the inverter-motor drive system in high speed region, which is used for square wave modulation, and the adopted OCC method is designed and analyzed in detail in the paper. Finally, the comparison between the performance of the adopted OCC scheme and the traditional square wave modulation is made, and the effectiveness and advantages of the OCC scheme are confirmed by simulation test.