Reduction of Torque and Flux Variations Using Fuzzy Direct Torque Control System in Motor Drive

This paper presents a fuzzy direct torque control (Fuzzy-DTC) IC, which is fabricated in a standard TSMC 0.18-μm 1P6M CMOS process. The proposed chip enhances the performance of the three-phase induction motor by reducing the variations of torque and flux with fuzzy theory. In general, the motor control system firstly calculates the stator´s magnetic flux and torque by detecting the current, voltage, and rotor speed of the three-phase induction motor. Using the torque error, magnetic error, fuzzy vector selection table and coordinate transformation, a suitable voltage space vector can be obtained to control the switches of MOSFET in inverter and to have a stable response in motor speed. Furthermore, the fuzzy controller and fuzzy vector selection table are used to establish an appropriate voltage vector with high operating speed and good stability. According to the simulation results, the proposed fuzzy DTC system performs with the coverage of 96.03 % and the fault coverage of 95.06 % at the operating frequency of 50 MHz, the supplied voltage of 1.8 V and the power consumption of 79.5 mW, and that the chip area of the proposed fuzzy DTC ASIC is 1.8x1.8 mm² involving pads.