Patent ID: 8886381
Filing Date: 2014-11-11
Classification: B60K,B60L,Y02T

Abstract:
1. An electric vehicle comprising: a motor unit configured to drive a drive wheel; a motor control circuitry configured to control the motor unit in accordance with a motor torque command value that is generated based on commands produced from an acceleration manipulation unit and a deceleration manipulation unit; a slip ratio estimator configured to estimate a slip ratio of the drive wheel on a road surface, based on a detection value indicating a travel speed of the vehicle and a rotational frequency of the drive wheel; a disturbance observer configured to estimate a torque that is attributable to external force that acts on the vehicle, based on the detection value indicating a travel speed of the vehicle and the motor torque command value; an applied torque estimator configured to estimate an entire torque applied to the drive wheel, based on (i) the motor torque command value or a motor current value of the motor unit and (ii) the torque estimated by the disturbance observer that is attributable to external force; a coefficient of friction estimator configured to estimate a coefficient of friction between a road surface and a tire of the drive wheel, based on the torque estimated by the applied torque estimator and the slip ratio estimated by the slip ratio estimator; a maximum acceptable torque determiner configured to determine, according to a predefine rule, a maximum acceptable torque, based on the estimated coefficient of friction and a vertical load component acting on the drive wheel; and a motor torque command value limiter configured to limit, based on the determined maximum acceptable torque, the motor torque command value to the motor unit that is generated responsively to the acceleration manipulation unit and the deceleration manipulation unit.