Hybrid Vehicle SOC Control via Freeway Engine Charging
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Solution Overview
Problem
Hybrid vehicles face increased total travel costs due to inefficient charging strategies, where external charging is not optimized based on fuel and electric power costs, leading to suboptimal state of charge (SOC) management during travel.
Innovation Solution
The hybrid vehicle employs an electronic control unit to switch between EV and HV travel modes, executing charging amount recovery control by comparing travel costs and adjusting the SOC target value during freeway travel to minimize total travel costs, using external charging strategically based on cost comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If external charging is uniformly performed without considering engine efficiency, then charging simplicity is improved, but total travel cost increases
Solution Approach 1:
The system dynamically changes the charging parameter (SOC target value) based on engine operation parameters. When engine efficiency is high, the SOC target value is increased to utilize engine output for charging, thereby reducing total travel cost while maintaining operational simplicity through automated control
Solution Approach 2:
The control unit continuously monitors engine operation state and adjusts the charging strategy accordingly. By feeding back engine efficiency information to the charging control system, the vehicle automatically optimizes charging timing and amount, resolving the contradiction between operational simplicity and cost reduction
2Productivity
If SOC target value is increased during freeway travel, then charging efficiency is improved, but fuel consumption increases
Solution Approach 1:
The system changes the SOC target value parameter dynamically based on engine operation conditions. During freeway travel when engine efficiency is high, the SOC target value is increased to maximize charging efficiency while the system compensates for fuel consumption by utilizing the high-efficiency engine operation window
Solution Approach 2:
The system performs preliminary charging action during freeway travel when engine efficiency is high, before reaching destinations where external charging would be more expensive. This preliminary charging reduces the need for expensive external charging later, offsetting the fuel consumption during freeway charging
3Object-generated harmful factors
If EV travel region is increased, then travel cost is reduced, but battery charge depletes faster
Solution Approach 1:
The system performs preliminary charging of the battery during freeway travel when engine efficiency is high, increasing the SOC before leaving the freeway. This preliminary action ensures sufficient battery charge is available for EV travel on open roads, allowing the vehicle to reduce travel cost by using EV mode without worrying about charge depletion
Solution Approach 2:
The system dynamically adjusts the EV travel region based on real-time SOC levels and route information. When SOC is sufficient after freeway charging, the EV travel region is expanded; when SOC is low, the system transitions to HV travel to recharge the battery, creating a dynamic balance between travel cost reduction and charge management
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
This approach reduces total travel costs by optimizing SOC levels and charging efficiency, allowing for lower fuel and electric power consumption, thereby minimizing charging costs and overall travel expenses.
Implementation Method 1
a motor generator that generates power by using electric power supplied from said battery
Implementation Method 2
an electric power generator mechanically coupled to the internal combustion engine and generating electric power to be charged to the electrical storage device by using power of the internal combustion engine
Data Source
AI summary
The electronic control unit sets a target value of a charging amount of the electrical storage device and increases the charging amount to the target value during traveling on the freeway. The electronic control unit computes a first travel cost being cost per unit travel distance of fuel used when the EV travel is made by using the electric power charged in the electrical storage device at a time when the HV travel is made on the freeway, and the second travel cost being cost per unit travel distance of the electric power used when the EV travel is made by using the electric power charged in the electrical storage device by the charging mechanism at the destination. The electronic control unit sets the target value on the basis of a comparison result between the first travel cost and the second travel cost.