Dual Battery Hybrid Vehicle Power Management

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Small-sized hybrid vehicles are unable to equip large batteries, resulting in insufficient charging power and inefficient engine operation, often running in low-load regions where engines have low efficiency.

Innovation Solution

A vehicle configuration that includes a first and second power storage device, with a supply device transferring power from the first to the second device, increasing engine load and efficiency by operating the engine in high-load regions, and stopping power transfer during no-load or idle operations to minimize losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a small battery is equipped in a small-sized hybrid vehicle, then the vehicle size and weight are reduced, but the charging power is insufficient and engine efficiency deteriorates

Engineering Contradiction:
Improvevehicle weightVSAvoidengine efficiency
Core Design Contradiction:
Weight of moving objectVSLoss of energy

Solution Approach 1:

The patent divides the power storage system into two separate batteries: a first battery for power storage and a second battery for power supply. This segmentation allows the first battery to be charged by the engine even at low loads, as the power can be stored in the first battery rather than requiring high-load operation. The second battery handles immediate power supply demands, enabling the engine to operate in efficient low-load regions while still achieving effective charging.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first battery acts as an intermediary between the engine and the second battery. It receives power from the engine through the generator and transfers it to the second battery, which supplies power to the motor. This intermediary structure allows the engine to operate at low loads while still charging the system effectively, resolving the contradiction between small battery size and charging capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If the engine operates in low-load region to match small battery charging needs, then the battery can be charged, but the engine efficiency becomes low

Engineering Contradiction:
Improvebattery charging capabilityVSAvoidengine efficiency
Core Design Contradiction:
Loss of energyVSUse of energy by moving object

Solution Approach 1:

By segmenting the battery system into first and second batteries with distinct functions, the patent enables the engine to charge the first battery even at low loads. The first battery serves as a buffer that accumulates energy from low-load engine operation, which is then transferred to the second battery for motor power supply. This resolves the contradiction by allowing effective charging without requiring high engine loads.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the operational parameters by introducing a dual-battery architecture that decouples the charging function from the power supply function. This allows the engine to operate in the low-load region (changing the load parameter) while still achieving effective energy transfer to the motor through the first battery's buffering capability, thereby maintaining both charging effectiveness and engine efficiency.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If a large battery is equipped to provide sufficient charging power, then engine efficiency can be improved, but the vehicle size and weight increase

Engineering Contradiction:
Improveengine efficiencyVSAvoidvehicle weight
Core Design Contradiction:
Use of energy by moving objectVSWeight of moving object

Solution Approach 1:

The patent segments the single large battery into two smaller batteries with specialized functions. The first battery is optimized for charging from the engine generator, while the second battery is optimized for high-power discharge to the motor. This segmentation allows each battery to be smaller and lighter than a single large battery would be, while collectively providing the same or better overall performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first battery serves multiple functions: it acts as a buffer for engine-generated power, a regulator for charging rates, and a source of auxiliary power. This multi-functionality reduces the need for a single large battery, allowing the system to achieve sufficient charging capability with smaller, lighter battery components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Use of energy by moving object

If power is supplied from the first battery to the second battery during engine load operation, then engine efficiency is improved, but system complexity increases

Engineering Contradiction:
Improveengine efficiencyVSAvoidpower supply system complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

While segmentation into two batteries does increase component count, it simplifies the control logic by creating clear functional separation. The first battery handles charging operations with simple charge/discharge control, while the second battery handles power supply to the motor. This functional segmentation makes the control strategy more straightforward compared to managing a single large battery with complex state-of-charge requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first battery serves as an intermediary that simplifies the interface between the engine generator and the motor battery. It absorbs the variability in engine output and provides a stabilized power source to the second battery, reducing the complexity of power management algorithms that would otherwise be needed to directly coordinate engine and motor operations.

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 configuration enhances engine efficiency by operating in high-load regions where engines perform better and reduces losses during no-load or idle conditions, improving overall fuel efficiency.

Implementation Method 1

the supply device is a converter

Methodology Applied
Scientific EffectElectrical energy conversion: Electrical Resistance

Data Source

PatentEP2749467B1Vehicle, and control method and control device for vehicle
Publication Date: 2018.01.10 TOYOTA JIDOSHA KK
  • EP2749467B1 patent drawingFigure 1
  • EP2749467B1 patent drawingFigure 2~3
  • EP2749467B1 patent drawingFigure 4

AI summary

A vehicle includes a traveling battery storing electric power, an auxiliary battery connected to the traveling battery, a DC/DC converter supplying the electric power from the traveling battery to the auxiliary battery, and an engine operated at a load corresponding to the electric power supplied from the traveling battery to the auxiliary battery. If the load of the engine is smaller than a threshold value during load operation of the engine, the DC/DC converter supplies the electric power from the traveling battery to the auxiliary battery.