Research of PMSM Fuzzy Direct Torque Controller Based on Sliding Mode Observer

In this paper, fuzzy control is introduced to reduce the big flux linkage and torque ripple of traditional PMSM DTC system. Simultaneously, using SVPWM to modulating voltages, using the full-order state observer to replace the integral part of the stator flux linkage observer, those method effectively reduce the dc drift, the integral error accumulation, other shortcomings and modulation precision. Moreover, a new position observing system was designed instead of the traditional position sensor in this control system. This design replaced the traditional switch functions with continuous saturation functions in the sliding mode observer, and the result showed the high frequency noise signal could be reduced effectively. By the experimenting for the traditional PMSM DTC system with stator flux linkage integral observer and the PMSM fuzzy DTC system with full-order state observer and sliding mode observer those are designed in this paper, the results show the control performance of the new fuzzy DTC system is better than the one of traditional DTC system evidently. The stator flux linkage and torque ripple of new system are decreased significantly. The new sliding mode observer could accurate observing position signal.