High-Performance Advanced Discontinuous PWM Algorithm for Direct Torque Controlled Induction Motor Drives for Reduced Ripple

摘要

In this paper a high performance advanced discontinuous pulse width modulation (ADPWM) based direct torque controlled (DTC) induction motor drive operating at high line side voltages is proposed. The proposed ADPWM based IM drive uses a special category of sequences which not only reduces the switching losses but also reduces the line current distortion during high speed operations. However analysis in this paper is limited to harmonic ripple in line current and comparison of the proposed method is done with the conventional DTC (CDTC), conventional space vector pulse width modulation (CSVPWM) based DTC and clamping sequences based DTC. The proposed method uses a special category of DPWM sequences, 0121 and 7212. This category of DPWM sequences are referred as double switching clamping sequences as they not only clamp one of the phase to either of the buses but also switches one of the remaining two phases twice in every sub cycle. In this paper it is shown that, utilizing DPWM sequences and by changing the zero state at any spatial angle ? ? ? where ? is between 00 and 600an infinite number of ADPWM methods can be generated which are categorized as continual clamping and split clamping sequences. It will be shown that steady state line current distortion at higher line side voltages is reduced significantly compared with the CDTC, CSVPWM based DTC as well as the ADPWM based DTC using clamping sequences.