Control Technique Analysis for Induction-Type Traction Motor Used in Electrical Vehicle
Date Issued
2012
Date
2012
Author(s)
Wu, Sheng-Yuan
Abstract
This thesis investigates the control techniques of induction-type traction motor for powering electric vehicles. The inner loop of the traction motor control system manages the electric torques delivered to the wheel, the outer loop aims at confining the wheel slip ratio to within a specified range. Induction-type traction motors are known for their firm structure. However, due to the rotor flux produced by the induced current, the torque control to an induction motor is quite complex, especially severe rotor flux fluctuations may occur during low speed drive. The enhanced V/f control technique makes use of a voltage compensation for low speed drive to elevate the torque quality, however, in terms of open-loop control. The direct torque control technique measures and manipulates the stator quantities for estimating and controlling the motor torque. The wheel slip control loop diminishes the drive torque or regenerative torque whenever the wheel tends to skid or lock up. The induction motor model and quarter car load is built in the simulation system as the controlled plant. The traction motor controller of the simulation system contains the wheel slip controller, the direct torque inverter and the enhanced V/F inverter. The performance of the traction motor control system based on the direct torque technique and on the enhanced V/F control technique have been examined and compared extensively through simulations. The results show that the direct torque control one performs better than that of the enhanced V/f control one in terms of the response of electrical torque, recovery of regenerative energy, tracking ability of wheel acceleration, drive stability either on wet or dry road.
Subjects
Electric vehicle
induction motor drive
direct torque control
wheel slip control
regenerative braking
Type
thesis
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