One-Pedal Drive Torque Control for Road Gradient Compensation
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Solution Overview
Problem
Existing one-pedal drive systems in hybrid/electric vehicles face challenges in efficiently transitioning between propulsion and braking, particularly on varying road gradients, and maintaining a stopped position without manual intervention.
Innovation Solution
A vehicle system incorporating an electric machine, friction brakes, and a controller that adjusts torque based on road surface gradients and pitch, using regenerative braking and compensation torque to ensure smooth transitions and maintain a stopped position, allowing for one-pedal operation without applying the brake pedal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is used to brake the vehicle in response to releasing the accelerator pedal, then energy recovery is improved, but braking control precision deteriorates on varying road gradients
Solution Approach 1:
The controller continuously monitors rotor position, vehicle speed, and accelerator pedal position to dynamically adjust the regenerative braking torque. This feedback mechanism ensures precise braking control on varying road gradients while maximizing energy recovery, resolving the contradiction between energy efficiency and control precision.
Solution Approach 2:
The system changes the torque parameter dynamically based on operating conditions. The controller adjusts the regenerative braking torque level according to rotor position, vehicle speed, and road gradient detection, enabling precise control across different scenarios while maintaining energy recovery efficiency.
2Stability of the object's composition
If friction brakes are used to maintain stopped position without depressing accelerator or brake pedals, then vehicle stability is improved, but energy consumption increases
Solution Approach 1:
The system uses the electric machine's electromagnetic drag effect to maintain the stopped position without continuous energy input. Once the vehicle stops, the electric machine naturally provides holding torque through electromagnetic forces, eliminating the need for continuous friction brake application and reducing energy consumption while maintaining stability.
3Measurement precision
If desired torque is adjusted based on road surface gradient, then propulsion accuracy is improved, but control complexity increases
Solution Approach 1:
The controller uses feedback from the accelerator pedal position sensor and gradient sensor to automatically adjust the desired torque. This feedback-based approach simplifies the control logic compared to complex open-loop calculations, achieving high propulsion accuracy while maintaining manageable control complexity.
Solution Approach 2:
The system performs preliminary torque adjustment based on detected gradient before the vehicle begins moving. By pre-calculating the compensation torque needed for the current gradient, the system simplifies real-time control while ensuring accurate propulsion response from the start of motion.
4Reliability
If compensation torque is applied when rotor moves opposite to desired direction, then system reliability is improved, but control complexity increases
Solution Approach 1:
The controller applies compensation torque in advance when it detects rotor movement opposite to the desired direction. This preliminary anti-action prevents the erroneous movement from affecting vehicle operation, improving reliability while using straightforward detection and correction logic that maintains acceptable control complexity.
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
Enables seamless propulsion and braking in hybrid/electric vehicles using one-pedal operation, effectively managing road gradients and maintaining a stopped position, enhancing driving efficiency and safety by automatically adjusting torque to compensate for pitch and gradient variations.
Implementation Method 1
The electric machine has a rotor, is configured to propel the vehicle in response to depressing the accelerator pedal
Implementation Method 2
The electric machine is configured to brake the vehicle via regenerative braking in response to releasing the accelerator pedal
Implementation Method 3
The friction brakes are configured to brake the vehicle in response to depressing the brake pedal
Data Source
AI summary
A vehicle includes an accelerator pedal, an electric machine, and a controller. The electric machine is configured to propel and brake the vehicle according to a one-pedal driving operation. The controller is programmed to, in response to depressing the accelerator pedal, command a desired torque to the electric machine. The controller is further programmed to, adjust the desired torque based on a gradient of a road surface that the vehicle is positioned on. The controller is further programmed to, in response to movement of the electric machine in a direction that is opposite to a desired direction while the adjusted desired torque is being applied, increase the adjusted desired torque by a compensation torque such that movement of the electric machine transitions to the desired direction.