Electric Vehicle Control Device for Slope Stop and Deceleration Vibration
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Solution Overview
Problem
Existing electric vehicle regenerative brake control systems experience acceleration vibrations during deceleration and inefficient electricity usage when holding a vehicle stop state, particularly on slopes, due to high regenerative braking forces and continuous motor current supply.
Innovation Solution
A control method and device that adjust motor torque to converge with disturbance torque estimates, switching from motor torque to friction braking to minimize current consumption and prevent acceleration vibrations, ensuring smooth deceleration and reduced electricity costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor torque is used to hold the vehicle stop state on a slope road, then the vehicle stop state can be maintained, but current consumption increases and electricity efficiency deteriorates
Solution Approach 1:
The patent introduces friction braking force as an intermediary to assist the motor in holding the vehicle stop state. By combining motor torque with friction braking force, the system can maintain the vehicle stop state on slope roads while reducing the motor's current consumption, thus resolving the contradiction between reliability and energy efficiency
Solution Approach 2:
The patent dynamically adjusts the motor torque command value based on vehicle speed parameters. As the vehicle speed approaches zero, the motor torque command value is reduced to converge toward the disturbance torque estimated value, which represents the minimum torque needed to counteract gravitational force on slopes. This parameter change enables the motor to maintain stop state with minimal current consumption
2Productivity
If regenerative braking force is increased to improve deceleration performance, then braking efficiency improves, but acceleration vibration occurs during deceleration
Solution Approach 1:
The patent dynamically adjusts the motor torque command value during deceleration based on the vehicle speed parameter. As speed decreases, the motor torque command value is continuously reduced to converge toward the disturbance torque estimated value. This dynamic adjustment prevents sudden changes in braking force that would cause acceleration vibration, while still achieving effective deceleration through regenerative braking
Solution Approach 2:
The patent uses feedback control by continuously monitoring the vehicle speed parameter and adjusting the motor torque command value accordingly. The control system compares the current speed with the target stop state and modulates the motor torque to achieve smooth deceleration without vibration, while maximizing regenerative braking efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces motor current consumption and eliminates acceleration vibrations during deceleration, improving electricity efficiency and ensuring smooth vehicle stop and start transitions across various road conditions.
Implementation Method 1
an electric motor for driving or braking wheels, and a motor controller that controls this electric motor
Implementation Method 2
the friction brakes that provide the friction braking force to the vehicle
Data Source
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AI summary
the control device for electric vehicle in the first embodiment, in the electric vehicle including the motor that functions as the traveling driving source and provides a regenerative braking force to the vehicle, and the friction brakes that provide the friction braking force to the vehicle, detects the motor rotation speed proportionate to a running speed of this electric vehicle, estimates the disturbance torque that acts on the motor, and performs the control such that the motor torque command value converges to the disturbance torque estimated value as the motor rotation speed decreases. Then, when the motor rotation speed becomes almost 0, the control device performs the control such that the friction-braking-amount command value with respect to the friction brakes converges to a value determined on the basis of the disturbance torque estimated value, and causes the motor torque command value to converge to almost 0.