Electrified Vehicle Powertrain Controller Engine Pull-Up Logic
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Solution Overview
Problem
Existing electrified vehicle powertrain control strategies fail to efficiently manage engine operation in relation to battery state of charge and driver-demanded torque, leading to suboptimal energy management and reduced fuel economy.
Innovation Solution
A controller-based engine pull-up/down logic that dynamically adjusts engine operation based on battery state of charge, driver-demanded torque, and vehicle conditions, inhibiting engine start or shutdown to prioritize energy recuperation and charge maintenance, allowing for efficient energy distribution between the engine and electric machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is run to charge the battery when SOC falls below a threshold, then the battery state of charge is improved, but fuel consumption increases
Solution Approach 1:
The engine pull-up/down logic dynamically adjusts engine operation based on real-time battery SOC levels, driver-demanded torque, and vehicle conditions. The controller modifies engine start/stop decisions based on whether the vehicle is accelerating, cruising, or braking, and whether driver-demanded torque is more negative than charge maintenance torque. This dynamic adaptation resolves the contradiction by charging the battery only when it does not significantly increase fuel consumption.
Solution Approach 2:
The system changes operational parameters (engine on/off state, charge maintenance torque thresholds) based on vehicle operating conditions. When driver-demanded torque is more negative than charge maintenance torque during acceleration or constant speed travel, the controller inhibits engine pull-up requests even if SOC is below threshold, thereby avoiding unnecessary fuel consumption while maintaining adequate battery charge levels.
2Loss of energy
If the engine is inhibited from starting when SOC is low during accelerator pedal release or braking, then energy recuperation is improved, but battery state of charge may fall below threshold
Solution Approach 1:
The controller issues inhibit engine pull-up commands in advance during accelerator pedal release or braking events when SOC is below threshold. This preliminary inhibition prevents the engine from starting during regenerative braking opportunities, maximizing energy recuperation. The system accepts temporary lower SOC levels in exchange for capturing kinetic energy that would otherwise be lost.
Solution Approach 2:
The system converts what would be a harmful condition (low battery SOC) into a benefit by inhibiting engine start during braking events. This allows maximum regenerative braking capability, transforming the low SOC state into an opportunity to recapture kinetic energy that can later be used to recharge the battery during subsequent driving cycles.
3Ease of operation
If the engine pull-up request is independent of driver demanded torque, then battery charging is simplified, but energy management efficiency is reduced
Solution Approach 1:
The engine pull-up/down logic transitions from a static, SOC-threshold-only control to a dynamic control system that continuously evaluates driver-demanded torque, vehicle acceleration state, and battery SOC levels. The controller compares driver-demanded torque against charge maintenance torque thresholds and adjusts engine operation accordingly, significantly improving energy management efficiency while maintaining control simplicity through automated decision-making.
Solution Approach 2:
The system implements feedback control by continuously monitoring driver-demanded torque and battery SOC levels, and adjusting engine pull-up/down decisions based on this feedback. The controller modifies EPUD logic in real-time based on the relationship between driver-demanded torque and charge maintenance torque, creating a closed-loop control system that optimizes energy management efficiency while responding to actual driving conditions.
Data Source
AI summary
A vehicle including an engine, an electric machine, a traction battery, and a controller is provided. The controller is programmed to, during acceleration or constant speed travel of the vehicle and responsive to state of charge of the battery falling below a first threshold, run the engine to charge the battery. The controller is further programmed to, during the running and responsive to first occurrence of the state of charge achieving a second threshold, accelerator pedal release, or braking of the vehicle, stop the engine. The controller may be further programmed to, during accelerator pedal release or braking of the vehicle and responsive to the state of charge falling below the first threshold, inhibit start of the engine. The controller may be further programmed to, during the inhibiting and responsive to acceleration or constant speed travel of the vehicle, run the engine to charge the battery.