Vehicle Electrical System with Segmented Energy Storage
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Solution Overview
Problem
Traditional lead acid batteries in start/stop systems for internal combustion engines face reduced battery life and require larger sizes to handle increased energy throughput, leading to limitations in handling frequent start/stop events and high current consumption.
Innovation Solution
An electrical system with a primary battery, alternator, and a third source of electrical energy (such as a super capacitor or lithium-ion battery) connected in parallel, where the third source is charged by the alternator and used to supply loads when the alternator is shut down, reducing the energy burden on the primary battery and enhancing redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional lead acid batteries are used in start/stop systems, then the system can provide fuel savings during city driving, but the battery life is significantly reduced and the battery size must be increased to handle increased energy throughput
Solution Approach 1:
The electrical energy storage system is segmented into multiple battery units with different characteristics. A first battery unit (traditional lead acid) handles engine starting, while a second battery unit (lithium-ion or similar) handles electrical loads during engine-off periods. This segmentation allows each battery type to operate in its optimal performance range, extending overall system life while maintaining fuel savings benefits.
2Duration of action of moving object
If traditional lead acid batteries are sized up to handle increased energy throughput, then the battery can fulfill required battery life, but the device complexity and weight increase
Solution Approach 1:
Instead of using one large battery, the system uses two smaller battery units with complementary roles. The lithium-ion battery unit has higher energy density and lighter weight for its capacity, reducing overall system weight while providing sufficient energy throughput handling capability.
3Ease of operation
If one large main battery and one smaller support battery are used, then the support battery can supply electrical system during warm-starts, but the system suffers limitations with increased start/stop events and higher current consumption
Solution Approach 1:
The system changes the electrical parameters (voltage, current handling capability) available to different parts of the electrical system based on engine state. During engine-off periods, the lithium-ion battery provides high current capability to support increased current consumption from modern electrical loads. The control system dynamically manages power distribution based on real-time conditions, ensuring reliability under varied start/stop event frequencies.
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 configuration significantly reduces the energy throughput on the primary battery, extends its life, and improves redundancy and weight efficiency in the electrical system, allowing for engine and alternator shutdown during driving, applicable to various vehicle types.
Implementation Method 1
an alternator and an electrical load in parallel with one another and selectively connectible in parallel with the primary battery via a first switch, and a third source of electrical energy selectively connectible in parallel with the alternator via a second switch
Implementation Method 2
a DC/DC converter in parallel with the alternator and arranged for selectively charging the third source of electrical energy via the second switch
Implementation Method 3
a primary battery connectible to an engine starter motor
Data Source
AI summary
An electrical system for a vehicle having an internal combustion engine provided with a start/stop system includes a primary battery connectible to an engine starter motor, an alternator and an electrical load in parallel with one another and selectively connectible in parallel with the primary battery via a first switch, and a third source of electrical energy selectively connectible in parallel with the alternator via a second switch. A DC/DC converter may be arranged in parallel with the alternator for selectively charging the third source of electrical energy via the second switch. A secondary battery may be arranged in parallel with the alternator.