HEV Controller Mode Selection Using Cost Functional Optimization
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Solution Overview
Problem
Existing hybrid electric vehicle (HEV) controllers face challenges in efficiently determining the optimal operational mode due to the unavailability of certain modes, leading to increased computational burden and potential mode chattering, which affects fuel efficiency and driver perception.
Innovation Solution
A controller that selects operational modes based on a cost functional using a control optimization methodology, allowing for the identification of the lowest cost mode and switching to alternative modes if the first choice is unavailable, with the ability to reference pre-calculated torque split data stored in databases to reduce real-time calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the controller evaluates all operational modes to determine the optimal mode, then fuel efficiency is improved, but computational burden increases
Solution Approach 1:
The patent pre-calculates and stores operational mode evaluations in lookup tables during system initialization or offline processing. During real-time operation, the controller simply queries these pre-computed tables based on current operating conditions, avoiding the need to evaluate all modes from scratch and thus reducing computational burden while maintaining fuel efficiency optimization
Solution Approach 2:
The patent divides the operational mode selection process into discrete, pre-defined modes stored in lookup tables. Instead of continuously evaluating all possible modes, the controller segments the operating space into distinct modes and selects from these predefined options, significantly reducing real-time computational requirements
2Use of energy by moving object
If the controller switches between operational modes frequently to optimize performance, then fuel efficiency improves, but mode chattering occurs affecting driver perception
Solution Approach 1:
The patent implements minimum dwell time constraints between mode transitions and uses hysteresis bands in mode selection logic. These pre-built protective measures prevent frequent switching by requiring a minimum time interval between mode changes and by creating buffer zones that prevent oscillation between modes, thus cushioning against mode chattering while maintaining optimization benefits
Solution Approach 2:
The patent applies counter-measures in advance to prevent mode chattering by implementing transition suppression logic that detects conditions likely to cause frequent switching and prevents transitions under those conditions. This preliminary anti-action stops mode chattering before it occurs, maintaining fuel efficiency while protecting driver perception
3Loss of energy
If the controller selects the lowest cost functional mode, then energy efficiency improves, but availability constraints may make the selected mode unavailable
Solution Approach 1:
The patent implements a feedback-based mode selection process where the controller first identifies the lowest cost functional mode, then checks its availability based on current system state constraints. If the optimal mode is unavailable, the feedback mechanism triggers a search for the next best available mode, ensuring both energy efficiency and adaptability to actual system conditions
Solution Approach 2:
The patent makes the mode selection process dynamic by allowing the set of available modes to change based on real-time system conditions such as battery state of charge, component operational status, and driving conditions. This dynamic adaptation ensures the controller always selects from currently available modes while maintaining energy efficiency optimization
Data Source
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AI summary
The present invention provides a controller for a hybrid electric vehicle and a respective method. The controller has a plurality of actuators (111, 117) each operable independently to provide torque to a driveline (123) of the vehicle, at least one of the actuators (111) being arranged to consume a fuel and at least one of the actuators comprising an electric machine (117) operable to be powered by energy storage means. The controller is operable to control the plurality of actuators to apply respective amounts of torque to a driveline (123) of the vehicle according to one of three or more operational modes of the vehicle. The respective amounts of torque are calculated responsive to a value of each of a first set of two or more operating parameters of the vehicle. The controller is arranged to select two or more of the operational modes responsive to the first set of operating parameters, the modes being selected responsive to a value of a cost functional. A first of the selected modes is the mode having the lowest cost functional according to a control optimisation methodology implemented by the controller. The controller is further configured to control the vehicle to assume the first of the selected modes, in the event the first selected mode is unavailable the controller being arranged to control the vehicle to assume another of the selected modes.