EV Driving Motor Torque Control for Post-Stop Jerk Reduction
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Solution Overview
Problem
Existing methods for reducing the jerk phenomenon in electric vehicles after stopping are ineffective in terms of responsiveness and often cause additional noise, vibration, and harshness (NVH) problems, as they primarily focus on correcting braking force before stopping rather than addressing the jerk that occurs immediately after the vehicle comes to a halt.
Innovation Solution
An apparatus and method that utilize a controller and vehicle state detection system to determine when the vehicle has stopped and generate a torque command for the driving motor to offset and reduce the jerk, using vehicle acceleration information from an acceleration sensor to apply a torque that minimizes the jerk felt by the vehicle and driver, thereby improving ride comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If braking force correction is applied before stop, then the jerk phenomenon can be reduced, but the actual vehicle braking state becomes different from driver's intention causing additional NVH problems
Solution Approach 1:
Instead of correcting braking force before stop as in prior art, this patent applies torque command to the driving motor immediately after stop completion is detected. This reverses the timing and approach: rather than modifying the braking action, it compensates for the jerk using the motor's torque capability after the brake is released, thereby avoiding distortion of the driver's intended braking state while still reducing jerk.
Solution Approach 2:
The driving motor acts as an intermediary device to compensate for stop jerk. Rather than directly modifying the braking system, the patent uses the motor's torque output as a mediating force to counteract the jerk phenomenon, allowing jerk reduction without interfering with the brake system's primary function and avoiding additional NVH issues.
2Productivity
If valve control is used to control hydraulic pressure of braking system immediately after stop, then braking force can be adjusted, but responsiveness is limited and additional NVH problems occur
Solution Approach 1:
The patent replaces the mechanical valve control system with an electric motor torque control system. By using the driving motor's electronic torque command capability instead of hydraulic valve control, the system achieves faster responsiveness while maintaining the ability to adjust braking force, thereby eliminating the responsiveness limitation inherent in valve-based systems.
3Object-affected harmful factors
If braking force is corrected before stop, then jerk can be reduced, but the method cannot effectively respond to jerk occurring after vehicle is stopped
Solution Approach 1:
The controller prepares by detecting stop completion state and detecting vehicle acceleration using an acceleration sensor just before jerk occurs. This preliminary detection and preparation of torque command allows the system to respond immediately when jerk is detected, ensuring effective response to post-stop jerk that prior art methods cannot achieve.
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
Effectively reduces the stop jerk phenomenon, enhancing ride comfort by using the driving motor's torque to offset the jerk within the compliance range of the vehicle's chassis and suspension system, without additional hardware or increased costs, and improves responsiveness in reducing the jerk occurrence.
Implementation Method 1
vehicle acceleration information detected by an acceleration sensor of the vehicle state detection part
Implementation Method 2
a vehicle body and the human body receive a force to be pulled in the driving direction due to an inertial force
Implementation Method 3
since the vehicle is an elastic body, a restoring force of the elastic body acts at an instant immediately after the tire is stopped on the road surface
Data Source
AI summary
An apparatus and a method reduce a jerk phenomenon of an electric vehicle occurring immediately after the electric vehicle is stopped. The method of reducing a stop jerk of an electric vehicle includes acquiring vehicle state information through a vehicle state detection part and determining whether the vehicle reaches a stop completion state based on the acquired vehicle state information. The method includes, when it is determined that the vehicle reaches the stop completion state, determining and generating a torque command for jerk reduction to offset and reduce a vehicle jerk immediately after the stop based on vehicle acceleration information detected by an acceleration sensor and includes controlling an operation of a driving motor according to the generated torque command for jerk reduction. The apparatus for reducing a stop jerk performs the method.