DC-DC Converter Control for Engine Battery Voltage Priority

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Solution Overview

Problem

Existing systems for charging secondary batteries from an alternator do not account for the charge state of the engine battery, leading to potential discharge of the engine battery, and complex, costly solutions are required to manage this effectively.

Innovation Solution

A power converter system with a DC-DC converter that includes a microprocessor to regulate charging based on the engine battery's voltage, ensuring it remains above a setpoint while prioritizing its charge, and only using excess energy to charge the secondary battery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the alternator charges the secondary battery, then the secondary battery charge level improves, but the engine battery may discharge below critical voltage levels

Engineering Contradiction:
Improvecharge level of secondary batteryVSAvoidengine battery voltage stability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The system continuously monitors the engine battery voltage and uses this feedback to dynamically control the charging current allocation. When engine battery voltage approaches the threshold, the system automatically reduces or stops charging the secondary battery, ensuring the engine battery maintains sufficient charge for critical functions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The charging system dynamically adjusts current distribution between batteries based on real-time voltage conditions. The alternator's charging output is not fixed but varies according to the engine battery's state, allowing the system to adapt to changing electrical demands and maintain reliability.

Inventive Principle:
Principle #15Dynamics

2Productivity

If the alternator charges both batteries simultaneously, then charging efficiency improves, but complex control systems are required to manage power distribution

Engineering Contradiction:
Improvecharging efficiencyVSAvoidcontrol system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The system uses the engine battery as an intermediary in the charging process. The alternator charges the engine battery first, which then acts as a buffer and secondary charge source for the secondary battery. This simplifies control logic by establishing a clear charging hierarchy rather than requiring simultaneous complex power distribution management.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The charging process is segmented into priority levels: the engine battery receives primary charging attention to ensure it maintains critical voltage levels, while the secondary battery receives secondary charging priority. This segmentation simplifies control by dividing the charging function into distinct phases rather than requiring simultaneous management of both batteries.

Inventive Principle:
Principle #1Segmentation

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

Ensures the engine battery is maintained at a sufficient charge level for critical functions while efficiently utilizing alternator energy to charge the secondary battery, preventing discharge and optimizing energy distribution.

Implementation Method 1

A DC-DC converter is provided between the first battery and the second battery

Methodology Applied
Scientific EffectElectrical energy transformation:

Implementation Method 2

the source of electrical energy is an alternator driven by an internal combustion engine

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4636987A1Power converter and charging system with power converter
Publication Date: 2025.10.22 NAVICO GROUP AMERICAS LLC
  • EP4636987A1 patent drawingFigure 1~2
  • EP4636987A1 patent drawingFigure 3
  • EP4636987A1 patent drawingFigure 4~5

AI summary

A system (10) includes a source of electrical energy (78), a first battery (14) electrically connected to and configured to be charged by the source of electrical energy (78), and a second battery (16) electrically connected to at least one load. A power converter module (30) is electrically connected between the first battery (14) and the second battery (16). The power converter module (30) is configured such that the source of electrical energy (78) is used to charge the second battery (16) only if a measured voltage of the first battery (14) is above a first setpoint voltage.