Hybrid EV Power Split Control With Dynamic SOC Referencing
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Solution Overview
Problem
Existing hybrid vehicle control systems struggle to optimally manage battery state-of-charge (SOC) and average engine power (AEP) across different drive cycles and ambient conditions, leading to suboptimal fuel economy, performance, emissions, and component life.
Innovation Solution
A dynamic SOC referencing system for plug-in series hybrid electric vehicles that tracks a dynamic reference SOC profile and maintains average engine power above a threshold, using a controller with modules for EV enabling, battery management, and dynamic SOC referencing, to optimize power split between the battery and engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single calibration or set of predetermined references is used for powertrain control, then the control system is simple to implement, but it cannot optimize fuel economy, emissions, and performance across different drive cycles and ambient conditions
Solution Approach 1:
The patent implements dynamic SOC referencing where the reference SOC profile is not fixed but adapts in real-time based on ambient conditions, drive cycle detection, and vehicle operating parameters. The controller continuously adjusts the reference profile to optimize powertrain performance across varying conditions, transforming the static control system into a dynamic one that responds to environmental and operational changes
Solution Approach 2:
The system incorporates feedback mechanisms by monitoring actual SOC, comparing it against the dynamic reference profile, and adjusting power split decisions accordingly. The controller uses feedback from ambient sensors, drive cycle detectors, and powertrain operating parameters to continuously refine control decisions, enabling adaptation without requiring complete re-calibration for each condition
2Use of energy by moving object
If the battery SOC is allowed to deplete completely, then more energy can be extracted from the battery, but it risks damaging the battery and reducing component life
Solution Approach 1:
The system performs preliminary actions by establishing a dynamic reference SOC profile that proactively prevents SOC from reaching dangerous depletion levels. The reference profile acts as a pre-set boundary that the control system maintains, ensuring the battery operates within safe charge ranges while still maximizing energy utilization. This preliminary constraint prevents battery damage before it can occur
Solution Approach 2:
The patent dynamically adjusts the SOC reference parameter based on battery state, temperature, and operating conditions. By changing the reference SOC threshold adaptively rather than using a fixed value, the system optimizes energy extraction while maintaining battery health. The parameter changes allow the system to push battery limits safely under favorable conditions while providing greater protection under stressful conditions
3Use of energy by moving object
If the engine operates at low power levels, then fuel economy improves, but emissions control and aftertreatment effectiveness deteriorate
Solution Approach 1:
The dynamic SOC reference profile serves as an intermediary mechanism that coordinates between fuel economy objectives and emissions control requirements. By adjusting the reference profile based on engine operating conditions, the system mediates power split decisions to ensure the engine operates in regions that satisfy both efficiency and emissions constraints, using the reference profile as the mediating control parameter
Data Source
AI summary
A system and method for power management of hybrid electric vehicles is provided. In some implementations, a plug-in series hybrid electric vehicle may include an engine, a motor/generator (MG), a traction motor, an energy storage device, and a controller. The controller is coupled to the engine and the MG to control operation of the engine and the MG such that a state-of-charge (SOC) of the energy storage device tracks a dynamic reference SOC profile during a trip and an average engine power (AEP) is maintained above a threshold. In some instances, maintaining AEP above a threshold supports emission control of the vehicle.