Simulation of DTC-CBSVPWM fed SPMSM Drive with Five-level Diode Clamped Inverter

In this paper a simulation analysis of DTC-CBSVPWM of SPMSM drive using five-level diode clamped inverter is analyzed. It has simple structure and provides dynamic behavior comparable with classical DTC. Direct Torque Control (DTC) is an accurate controller for permanent magnet synchronous motor (PMSM) due to its robust and fast torque response in steady-state and transient operating condition. However, the main disadvantage of DTC is high ripples in stator current, flux linkage and torque due to the application of same active voltage vector during the whole sample period and possibly several consecutive sample intervals. This can be overcome by using proper modulation technique. Space Vector Modulation (SVM) which synthesizes any voltage vector lying inside the sextant gives good performance, but however the complexity involved is more in calculating angle and sector. To reduce the complexity involved in SVPWM, a novel modulation technique named Unified voltage modulation or carrier based space vector pulse width modulation (CBSVPWM) is described using the concept of effective time. By using this method the inverter output voltage is directly synthesized by the effective times and the voltage modulation task can be greatly simplified. The actual gating signals for each inverter arm can be easily deduced as a simple form using the effective time relocation algorithm.