Electric Motor Torque Control for Uphill Stall Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Control devices for electric motor-driven vehicles face challenges in preventing overload and backward movement during stalled states, especially when the vehicle is stopped on an uphill road, due to the slow response of hydraulic brake pressure changes.
Innovation Solution
A control device that performs driving force limit control based on the coefficient of static friction, reducing the electric motor's driving force when the vehicle is stalled and the accelerator pedal is depressed, thereby preventing overload and backward movement without relying on braking power, and adjusts the driving force to ensure immediate movement when requested.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If braking power is used to compensate for decrement in electric motor output torque during stalled state, then overload is prevented, but vehicle cannot move rapidly when accelerator pedal is depressed due to slow hydraulic pressure response
Solution Approach 1:
The patent replaces the hydraulic brake system with an electric motor control system. Instead of using brake torque to compensate for motor torque decrement, the system controls the electric motor's output torque directly through electronic control, eliminating the need for hydraulic pressure changes and enabling immediate response when the accelerator pedal is depressed.
Solution Approach 2:
The patent changes the control parameter from brake hydraulic pressure to electric motor torque instruction value. By adjusting the motor torque instruction value in real-time based on vehicle state and accelerator pedal position, the system achieves rapid response without the inertia of hydraulic pressure changes.
2Temperature
If electric motor output torque is decreased to prevent overheating of source power supply circuit, then thermal overload is prevented, but vehicle movement is delayed when driver depresses accelerator pedal
Solution Approach 1:
The patent implements a feedback control system that continuously monitors vehicle state (including temperature conditions) and adjusts the motor torque instruction value accordingly. When the vehicle is stalled and temperature rises, the system reduces torque to prevent overheating. When the accelerator pedal is depressed, the system immediately detects this input and adjusts torque upward without delay, eliminating the time loss associated with hydraulic brake response.
3Stability of the object's composition
If braking power is increased to maintain vehicle position on uphill road, then backward movement is prevented, but vehicle cannot move rapidly when starting is requested
Solution Approach 1:
The patent implements dynamic torque control where the electric motor's output torque is continuously adjusted based on real-time vehicle conditions. On uphill roads, the system provides sufficient torque to prevent backward movement. When the accelerator pedal is depressed, the system dynamically increases torque immediately, eliminating the delay caused by hydraulic brake pressure changes and enabling rapid starting movement.
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 prevents overload and backward movement by reducing the electric motor's driving force based on static friction, allowing the vehicle to move immediately when the stall condition is resolved, while avoiding unnecessary control actions and minimizing fuel consumption.
Implementation Method 1
a transport vehicle configured to travel with a driving force output from an electric motor
Implementation Method 2
the control device performs a driving force limit control to reduce the driving force of the electric motor based on a coefficient of static friction of the transport vehicle
Data Source
AI summary
A control device for a transport vehicle configured to travel with a driving force output from an electric motor is provided. When the transport vehicle is driven by a driving force of the electric motor, the control device performs a driving force limit control to reduce the driving force of the electric motor based on a coefficient of static friction of the transport vehicle in a case of satisfying conditions that a parameter relating to a traveling speed of the transport vehicle is less than a first threshold value and a state in which the parameter is less than the first threshold value continues for a predetermined time or more.