Hybrid Vehicle Power Split Using Transient Engine Load Control
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Solution Overview
Problem
Existing methods for operating hybrid vehicles fail to optimally adjust the load point of the internal combustion engine during transient operations, leading to suboptimal fuel consumption due to deviations in emissions and efficiency from steady-state conditions.
Innovation Solution
A method that uses dynamic quantities to determine the optimal load point of the combustion engine by employing a Hamiltonian function and Pontryagin's extremal principle, considering transient efficiency and constraints such as electrical losses and emissions, to adjust the power distribution between the internal combustion engine and electric drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steady-state operation data is used to determine operating strategy, then the control system is simple and computationally efficient, but the load point determination becomes suboptimal during transient operation leading to increased fuel consumption
Solution Approach 1:
The patent applies dynamics by transitioning from static steady-state efficiency maps to dynamic transient efficiency modeling. The system now accounts for time-varying efficiency characteristics during transient operation, allowing the load point determination to adapt to changing operating conditions. This dynamic approach resolves the contradiction by enabling accurate fuel consumption optimization during transients without requiring overly complex computational models, as the transient efficiency can be derived from measured data and simplified mathematical relationships.
2Productivity
If transient operation characteristics are accounted for in load point determination, then fuel consumption optimization improves, but the computational effort and system complexity increase
Solution Approach 1:
The patent applies parameter changes by introducing transient efficiency as a new parameter that varies with operating conditions. Instead of using fixed steady-state efficiency values, the system now uses time-varying transient efficiency parameters that capture the altered performance characteristics during transients. This allows improved fuel consumption optimization while keeping the overall system structure relatively simple, as the transient efficiency can be determined from measured data and incorporated into existing control algorithms.
Solution Approach 2:
The patent applies feedback by using measured operating data (such as actual fuel consumption, power output, and operating conditions) to continuously update and refine the transient efficiency determination. This feedback mechanism allows the system to adapt to real-world transient behavior and improve load point determination accuracy over time, resolving the contradiction by providing a practical way to incorporate transient characteristics without requiring excessively complex predictive models.
3Ease of operation
If static quantities are used for load point determination, then the control algorithm is simple and fast, but the load point adjustment is insufficient during transient operation resulting in suboptimal fuel consumption
Solution Approach 1:
The patent applies preliminary action by pre-determining transient efficiency characteristics from measured operating data before they are needed for control decisions. By collecting and analyzing data during transient operations in advance, the system builds a database of transient efficiency behavior that can be quickly referenced during actual transient events. This resolves the contradiction by preparing the necessary transient efficiency information beforehand, allowing simple and fast control algorithms to access accurate transient characteristics without performing complex real-time calculations.
Data Source
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AI summary
The invention relates to a method for operating a hybrid vehicle, particularly a diesel hybrid vehicle, comprising an internal combustion engine (12) and an electric drive (14). According to the invention, a total power applied in order to drive the vehicle is divided according to a distribution ratio to the internal combustion engine (12) and the electric drive (14). At least in one transient mode of the internal combustion engine (12), dynamic parameters are used to determine an optimal load point of the internal combustion engine (12).