Drive Axle Control for Excess Regenerative Power During Coasting
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Solution Overview
Problem
Electrified vehicles face challenges in managing regenerative power when torque accuracy is poor, leading to unabsorbed energy that can potentially overcharge the electric power source, especially when propulsion and regenerative braking torques are not requested.
Innovation Solution
A method and system that provides electrical energy from an external source to the electric motor to offset regenerative power, using a controller to manage torque based on vehicle motion and pedal inputs, ensuring the electric power source can absorb or discharge excess regenerative power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative power is allowed to be generated by the electric motor during coasting, then energy recovery is improved, but the electric power source may be overcharged when the electric power source cannot absorb the regenerative power
Solution Approach 1:
The controller continuously monitors the regenerative power generated by the electric motor and the absorption capacity of the electric power source. When the regenerative power exceeds the absorption capacity, the controller activates the offsetting mechanism by providing propulsion torque from the electric power source to counteract the excess regenerative power, preventing overcharging while maximizing energy recovery.
Solution Approach 2:
The system dynamically adjusts the net torque command to the electric motor based on real-time conditions. When offsetting regenerative power is required, the controller modifies the torque parameter by adding propulsion torque to counteract the regenerative braking torque, thereby controlling the amount of power charged to the electric power source and preventing overcharging.
2Measurement precision
If expensive hardware is used to ensure precise torque accuracy, then regenerative power management is improved, but system cost increases
Solution Approach 1:
The controller acts as an intermediary that compensates for torque accuracy limitations of less precise (and therefore less expensive) hardware. By continuously monitoring regenerative power and using the electric power source to provide offsetting propulsion torque, the controller achieves accurate regenerative power management without requiring expensive high-precision torque sensors or control hardware.
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 manages regenerative power by counteracting it with propulsion torque, preventing overcharging and allowing the use of less expensive hardware, thus optimizing energy management and reducing system costs.
Implementation Method 1
regenerative power that is generated by the electric motor when the vehicle is in motion
Implementation Method 2
electric power source cannot absorb the regenerative power generated by the electric motor
Implementation Method 3
Providing electrical energy from the electric power source to the electric motor may provide propulsion torque that counteracts the regenerative power
Data Source
AI summary
A vehicle having a drive axle system and a method of control. Electrical energy is provided from an electric power source to an electric motor to offset regenerative power generated by the electric motor when the vehicle is in motion and braking and acceleration of the vehicle are not requested.