Motor Torque Stop Waveform Control for Smooth Vehicle Braking
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Solution Overview
Problem
Existing control devices for vehicles with rotating electric machines struggle to effectively suppress vibrations and discomfort during braking, particularly when stopping, due to sudden changes in braking force and torsional releases in power transmission members.
Innovation Solution
A control device that includes an operation controller, first and second torque detectors, and a waveform setter to set a stop waveform for the rotating electric machine, gradually changing the braking/driving torque from a traveling torque to a standstill torque, ensuring a smooth stop process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the braking force is continuously generated according to the amount of brake actuation until the vehicle is brought to a stop, then the braking control is simple and responsive, but the vehicle vibrates significantly in the longitudinal direction after stopping, causing discomfort to occupants
Solution Approach 1:
The control device performs preliminary action by detecting the power transmission member's torsional state before the vehicle stops and proactively adjusting the braking force in advance. The operation controller reduces the braking force generated by the rotating electric machine when torsional release is detected, preventing the vibration issue before it occurs rather than reacting after the vehicle stops.
Solution Approach 2:
The control device implements feedback by using the torque detector to continuously monitor the torque of the power transmission member during braking. This feedback information about torsional state is fed back to the operation controller, which adjusts the braking force accordingly, creating a closed-loop control system that responds to real-time mechanical conditions.
2Use of energy by moving object
If the amount of regeneration is limited to a smaller amount as vehicle speed decreases when the vehicle is about to come to a stop, then energy recovery is optimized, but vibrations are not sufficiently suppressed when stopping
Solution Approach 1:
The control device uses feedback from the torque detector to monitor power transmission member torsion during the stopping process. When torsional release is detected, this feedback triggers the operation controller to adjust the braking force independently of the vehicle speed-based regeneration limits, enabling vibration suppression while maintaining optimized energy recovery at different speeds.
Solution Approach 2:
The control device applies dynamics by making the braking force adjustable and variable based on real-time torsional conditions. Rather than using fixed regeneration limits based only on vehicle speed, the system dynamically modifies the braking force in response to detected torsional release, adapting the control strategy to the actual mechanical state of the power transmission system.
3Speed
If sudden changes in braking force occur during stopping, then the stop response is quick and efficient, but torsional releases in power transmission members cause vibrations and discomfort
Solution Approach 1:
The control device performs preliminary detection of torsional state using the torque detector before the vehicle comes to a complete stop. When torsional release is detected in advance, the operation controller proactively adjusts the braking force to prevent sudden changes that would cause vibration, while still maintaining quick stop response through controlled braking adjustments.
Solution Approach 2:
The torque detector provides continuous feedback about the power transmission member's torsional state during the stopping process. This feedback enables the operation controller to detect torsional release and respond by adjusting the braking force, creating a responsive control system that balances quick stop response with vibration prevention through real-time monitoring and adjustment.
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 device effectively reduces vibrations and discomfort by smoothly transitioning the braking force, allowing the vehicle to stop without sudden changes, thus maintaining a stable and comfortable ride.
Implementation Method 1
Vehicles equipped with rotating electric machines as driving force sources for traveling have undergone a widespread distribution. Such rotating electric machines are also called 'motor generators.' In a vehicle equipped with a rotating electric machine, the driving force of the rotating electric machine is used not only during acceleration of the vehicle, but also during deceleration of the vehicle.
Data Source
AI summary
A control device for a vehicle includes an operation controller that controls operations of a rotating electric machine mounted to the vehicle, a first torque detector that detects a traveling torque which is a braking/driving torque to be output from the rotating electric machine when the vehicle is traveling, a second torque detector that detects a standstill torque which is a braking/driving torque to be output from the rotating electric machine upon the vehicle coming to a stop, and a waveform setter that sets a stop waveform which is a waveform indicating a time variation in the braking/driving torque output from the rotating electric machine from the traveling torque to the standstill torque. The operation controller performs a stop process that is a process to bring the vehicle to a stop while changing the braking/driving torque output from the rotating electric machine in accordance with the stop waveform.