Vehicle slip control system and method

Abstract

A vehicle is equipped with a motor that receives a supply of electric power, which is output from a battery and is boosted up by a DC / DC converter circuit, via an inverter circuit and outputs a torque to a drive shaft. In response to an estimated variation in road surface condition based on a decrease in angular acceleration of the drive shaft to be less than a threshold value ref during a slip, the control procedure of the invention adds a predetermined value to a torque upper limit Tmax, which is set at the time of the occurrence of the slip, and thereby updates the torque upper limit Tmax to start cancellation of torque restriction. The control procedure then updates the torque upper limit Tmax by a slope of a small time change to restrain the degree of cancellation of the torque restriction. After elapse of a preset time period specified as a waiting time to stabilize the voltage-increasing operation of the DC / DC converter circuit, the control procedure updates the torque upper limit Tmax by a slope of a greater time change to promptly cancel out the torque restriction.

Description

technical field [0001] The present invention relates to a technology applied to a vehicle and a control method of the vehicle. Background technique [0002] A proposed vehicle detects the occurrence of slippage caused by idling of the drive wheels when the rate of change of the angular velocity (angular acceleration) of the drive wheels is not less than a preset level, and limits the torque output from the motor to the drive shaft (for example, See Japanese Patent Laid-Open No. Hei 10-304514). [0003] In response to the reduction in angular acceleration caused by torque limiting, prior art vehicles detect that slip is converging and release the limitation of torque output to the drive shaft. However, such release of the torque limitation may lead to unstable power supply to the motor. The vehicle generally has a booster circuit that increases the voltage of the battery and outputs a voltage-increased power supply to the motor. In the case of a slip that converges in a sh...

AI Technical Summary

Problems solved by technology

In such a case where the torque limit is suddenly released, the increase in the voltage supplied by the booster circuit is delayed, and it is not possible to supply power to the motor with a sufficiently increased output voltage.

This can cause excessive current to flow through the electrical system containing the motor

Images