Research On Fuzzy Direct Torque Control System For Induction Motor Of Hybrid Electric Vehicle

Hybrid Electric Vehicles(HEV) combines the advantages of conventional engine-driven vehicles and pure Electric Vehicles(EV).This provides satisfied driving performance and lower exhaust emission.Thus,HEV is a feasible solution to solve the energy crisis and environmental pollution problems.There are mainly three hybrid driving structures for the HEV at present:Series Schedule,Parallel Schedule and Series-Parallel Combined Schedule.The structures and features of the three hybrid power systems are analyzed in this paper.The different structures of the parallel type are introduced and analyzed emphatically.Parallel type Hybrid Electric Vehicles drive system model is established.It is embedded in the ADVISOR.Model and control strategy is simulated.Drive motor being a main department of HEV,plays an important part in HEV development.So research and analysis on drive motor have a great significance.In this paper,fuzzy direct torque control system of induction motor is used as parallel type Hybrid Electric Vehicles drive system.Direct torque control of induction motor,which follows the field-oriented control,is a new control method for motor drive.The conventional Direct Torque Control(DTC) does not require rotating coordinate transformation and any current regulator,it controls torque and flux directly based on their instantaneous errors.In spite of its simplicity,direct torque control is able to produce very fast torque response and is robust with respect to motor parameters changes.However,insteady-state operation,notable torque,flux and acoustical noise occur.In this paper,aimed at the problem of notable torque ripples in conventional DTC,two improved schemes using newly-emerged strategies are described,and then,a novel scheme that can minimize torque ripples is proposed.In this paper,two improved schemes of fuzzy direct torque control are discussed and analyzed detailed.In the first improved schemes,a fuzzy logic controller is adgpted, instead of hysteresis controllers of torque and flux.It can improve dynamic response speed, but effect is not obvious in decreasing torque ripples.The other scheme of fuzzy direct torque control scheme is based on Discrete Space Vector Modulation(SVM).Using SVM, It can generate a number of voltage vectors higher than that used in conventional DTC scheme.And then,a fuzzy logic controller is used to select optimum voltage vector.It can decrease torque ripples increasingly.At last,simulation result demonstrates effectiveness of two improved schemes.In the simulation,fuzzy control technology and voltage space vector module technology is used,and it is proved to be effective.The novel design shows improvement over parallel HEV of Advisor 2002 and is validated as a viable HEV design.