Application of a Composite Estimator of Tire Force to the Driving Torque Strategy for an Electric Vehicle Driven by Multiple Motors
Date Issued
2016
Date
2016
Author(s)
Chen, Chien-Kuo
Abstract
This research proposes a new approach of estimator of tire force for electric vehicle (EV), which combines two different ways of estimating tire longitudinal force. The two methods are based on different analytical methods. The normal tire longitudinal force estimation analyzes single wheel model, but composite estimation analyzes not only tire model but also vehicle model. This composite estimator system is based on the powertrain of EV consists of three motors: a 15-kW front traction motor with gearbox and two 7-kW in-wheel motors installed inside both rear wheels. This configuration not only provides the vehicle good performance for planar motion control, but also improves driving efficiency of vehicle by driving and regenerative braking torque distribution of three motors. This research is found upon the sensors which configured in the EV of this laboratory to design an estimator system which can provide parameters to the distribution strategy of energy conservation and security. This estimator provides data to distribution strategy and allow it to calculate each torque of motors according to driver’s order. The strategy will adjust torque command of motors by particle swarm optimization (PSO) that makes motor operate in high efficiency region The torque distribution algorithm can improve driving efficiency by minimizing each instantaneous cost power and maximizing each instantaneous recovery power. In addition, in order to enhance the safety of vehicle driving, this research further develops the strategy by integrating electronic stability program (ESP), which is composed by slip ratio controller (SRC) and direct yaw-moment controller (DYC). Finally, this research verifies the accuracy of estimator and distribution strategy by model-in-the-loop (MIL) simulation. The vehicle model is designed from the software CarSim. Experimental results show that the composite estimator can calculate the values more accurately than traditional estimator, which can make ESP work more effiecntly than before. According to this data, the torque distribution strategy can ensure the driving safety by ESP and save energy when EV is either driving or braking on straight or curve roads.
Subjects
tire-force estimator
composite estimator
particle swarm optimization
energy conservation
vehicle stability control
torque distribution
electric vehicle
SDGs
Type
thesis
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