Motor Control Unit Reverse Torque for Shorter AEB Braking Distance
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Solution Overview
Problem
Conventional automatic emergency braking (AEB) systems in electric vehicles require a hydraulic system to build up pressure for braking, leading to a prolonged braking distance due to the time needed for pressure build-up, which can increase the risk of false triggering and compromise safety.
Innovation Solution
A motor control unit is employed to quickly output a reverse torque from the drive motor to complement the braking system, shortening the braking distance by coordinating with the hydraulic braking system to ensure timely deceleration without additional hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the hydraulic braking system is used to complete the entire AEB process, then the braking force is sufficient, but the pressure build-up time is long and the braking distance is increased
Solution Approach 1:
The motor control unit performs preliminary braking action by outputting reverse torque before the hydraulic braking system completes its pressure build-up. This preliminary action reduces vehicle speed during the time delay period, ensuring that when the hydraulic braking force eventually applies, the vehicle has already undergone initial deceleration, thereby shortening the overall braking distance without compromising the sufficiency of the final braking force
Solution Approach 2:
The patent merges the electric motor braking capability with the hydraulic braking system to create a cooperative braking mechanism. The motor control unit and hydraulic braking system work in parallel during the AEB process, with the motor providing immediate response and the hydraulic system providing sustained braking force, thereby combining the advantages of both systems to resolve the contradiction between response time and braking force
2Reliability
If the recognition distance is limited to avoid false triggering, then the false trigger rate decreases, but the braking distance may be increased
Solution Approach 1:
The patent replaces part of the mechanical hydraulic braking response with an electric motor response system. The motor control unit can immediately output reverse torque upon receiving the AEB signal, providing an electrical/electronic response mechanism that is faster than the mechanical hydraulic pressure build-up, thereby enabling shorter braking distances even when recognition distance is limited to reduce false triggering
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 motor control unit effectively reduces the emergency braking distance and enhances safety by ensuring rapid deceleration, minimizing the risk of wheel locking and false triggers, while maintaining vehicle control.
Implementation Method 1
The motor control unit outputs an alternating current to a three-phase stator winding, to control the motor to output the torque. The motor control unit can change intensity and a direction of a magnetic field of a stator by adjusting a magnitude of a current input into the stator winding and a phase of the three-phase current, thereby changing an interaction force between the stator and the rotor
Data Source
AI summary
A motor control unit, a method, and an electric vehicle. The motor control unit is configured to control the drive motor to output a reverse torque after the automatic emergency braking system is triggered and before the automatic emergency braking system outputs the braking force in a traveling process of the electric vehicle. A direction of the reverse torque is opposite to a rotation direction of the drive motor. According to this solution, a braking distance of AEB is shortened or an AEB intervention vehicle speed is increased when a braking distance of AEB remains unchanged, to reduce a false trigger rate of AEB, and improve vehicle safety.