Motor Control Unit Reverse Torque for Shorter AEB Braking
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Solution Overview
Problem
The conventional automatic emergency braking (AEB) systems in electric vehicles require a hydraulic system to build up pressure for braking, which takes a significant amount of time, leading to increased braking distances and potential false triggers.
Innovation Solution
A motor control unit is employed to quickly output a reverse torque from the drive motor to compensate for the hydraulic braking force buildup time, coordinating with the braking system to reduce the emergency braking distance and enhance safety.
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 controlling the drive motor to output reverse torque during the hydraulic pressure build-up phase. This preliminary action reduces vehicle speed before the hydraulic braking force fully engages, effectively compensating for the time delay in hydraulic system response.
Solution Approach 2:
The patent merges the motor braking system and hydraulic braking system into a coordinated dual-braking architecture. The motor control unit and braking system work together, with the motor providing immediate braking torque and the hydraulic system providing sustained braking force, achieving both rapid response and sufficient braking capability.
2Reliability
If the recognition distance is limited to avoid false triggering, then the false trigger rate is reduced, but the braking distance needs to be reduced further
Solution Approach 1:
The motor control unit initiates braking action immediately upon AEB trigger signal, performing preliminary deceleration before the hydraulic system fully engages. This preliminary action reduces the overall braking distance, allowing for safer recognition distance thresholds and reducing false trigger concerns.
3Loss of time
If the drive motor outputs reverse torque during AEB, then the braking distance is shortened, but the coordination with braking system must be precise
Solution Approach 1:
The motor control unit receives feedback signals from the braking system regarding hydraulic pressure status and braking force output. Based on this feedback, the motor control unit dynamically adjusts the reverse torque output, ensuring precise coordination between the motor braking and hydraulic braking systems throughout the AEB process.
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 shortens the emergency braking distance and reduces false triggers by leveraging the drive motor's rapid torque response, ensuring timely deceleration without additional hardware costs.
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, that is, controlling the torque output by the drive motor.
Data Source
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AI summary
A motor control unit and control method for shortening an emergency braking distance, and an electric vehicle are provided, relate to the field of new energy vehicles, and may be applied to a pure electric vehicle and a hybrid vehicle. The motor control unit is used in an electric vehicle, the motor control unit is configured to control a drive motor of the electric vehicle to output a positive torque to drive a wheel of the electric vehicle, the electric vehicle further includes an automatic emergency braking system, and the automatic emergency braking system is configured to output a braking force after being triggered, to brake the electric vehicle. The motor control unit is further 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 speed 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.