Vehicle Solar Charging Control with Sub-Battery Power Segmentation

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Solution Overview

Problem

Existing vehicle charging systems face inefficiencies when using in-vehicle solar cells, as the generated power often cannot meet the demands of electronic components during travel, leading to complex control systems and increased development costs, and the charging management becomes complicated due to competition among power sources.

Innovation Solution

A charging control device that includes a motor generator, main battery, sub-battery, electric power supply unit, and charging control unit, which disconnects power from the main battery during travel to prevent direct charging and stores it in the sub-battery, allowing efficient use of solar-generated power without complex high-voltage management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the solar cell directly charges the main battery during vehicle travel, then the main battery can be charged with solar power, but the power supply stability deteriorates due to competition between solar power and motor generator power

Engineering Contradiction:
Improvesolar power utilizationVSAvoidpower supply stability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent divides the battery system into two segments: main battery for motor generator charging and sub-battery for solar cell charging. This segmentation isolates the power sources, preventing competition between solar power and motor generator power, thereby maintaining power supply stability while enabling solar power utilization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sub-battery acts as an intermediary between the solar cell and the main battery. Solar power is first stored in the sub-battery, which then supplies power to the main battery when needed. This intermediary approach prevents direct competition between power sources while enabling solar power to contribute to main battery charging.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If complex control systems are implemented to manage multiple power sources, then power management efficiency improves, but device complexity increases

Engineering Contradiction:
Improvepower management efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

By segmenting the battery system into main battery and sub-battery with clearly defined roles, the control logic is simplified. The control device only needs to manage basic charging/discharging operations for each battery type, avoiding complex multi-power-source arbitration algorithms while maintaining efficient power management.

Inventive Principle:
Principle #1Segmentation

3Loss of energy

If the solar cell power is used to charge the main battery during travel, then energy utilization improves, but the electronic component power supply reliability deteriorates due to power competition

Engineering Contradiction:
Improveenergy utilization efficiencyVSAvoidelectronic component power supply reliability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent creates separate power supply pathways: motor generator charges main battery, solar cell charges sub-battery. This segmentation ensures electronic components receive stable power from the main battery while solar power is captured in the sub-battery without causing power competition, thus maintaining both energy utilization efficiency and power supply reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sub-battery serves as an intermediary storage device that accumulates solar power and releases it to the main battery when needed. This intermediary approach allows solar power to be utilized effectively without directly competing with the motor generator for main battery charging, thereby preserving electronic component power supply reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution enables efficient use of solar-generated power by storing it in a sub-battery during travel and transferring it to the main battery when stationary, reducing development costs and avoiding complex control systems, thereby enhancing power management and utilization.

Implementation Method 1

a solar cell configured to charge the in-vehicle battery

Methodology Applied
Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentEP3907096B1Charging control device using in-vehicle solar cell
Publication Date: 2025.01.08 TOYOTA JIDOSHA KK
  • EP3907096B1 patent drawingFigure 1
  • EP3907096B1 patent drawingFigure 2
  • EP3907096B1 patent drawingFigure 3

AI summary

A solar ECU (31) included in a charging controller (30) is configured to temporarily store electric power generated by an in-vehicle solar cell (21) of an electric power supply unit (20) in a low-voltage battery (22) when a vehicle (100) is traveling. Further, when the vehicle (100) is traveling, a battery ECU (32) included in the charging controller (30) is configured to maintain a charging relay (27) in an open state (disconnected state) so that the electric power temporarily stored in the low-voltage battery (22) is not supplied to a main battery (18). On the other hand, when the vehicle (100) is traveling, the solar ECU (31) supplies the electric power temporarily stored in the low-voltage battery (22) to a sub-battery (19).