Dedicated Key-Off DCDC Conversion for EV Auxiliary Loads

Solution Overview

Problem

Existing electric vehicles face inefficiencies in providing power to key-off functions when the vehicle is turned off, leading to increased battery wear and tear or high energy consumption, which reduces vehicle range and increases maintenance costs.

Innovation Solution

A dedicated DCDC conversion system that uses a micro DCDC converter to supply power to key-off modules from the propulsion battery, eliminating the need for a 12V battery and reducing power consumption by operating only when necessary, thereby decreasing the electrical overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a 12V battery is continuously cycled to provide power to key-off functions, then key-off electrical loads can operate, but battery wear and tear increases and replacement frequency increases

Engineering Contradiction:

Improvekey-off function availabilityVSAvoidbattery service life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent segments the power conversion function by introducing a dedicated key-off DCDC converter that operates independently from the main power train DCDC converter. This dedicated converter handles only key-off electrical loads, separating this function from the main propulsion power management system and eliminating the need for continuous 12V battery cycling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The key-off DCDC converter acts as an intermediary device between the high-voltage propulsion battery and the low-voltage key-off electrical loads. It directly converts power from the propulsion battery to supply key-off functions, eliminating the need for the 12V battery to serve as an intermediate energy storage device.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the main DCDC converter in the power train is kept active to supply key-off loads, then key-off functions can operate, but energy consumption increases and vehicle range decreases

Engineering Contradiction:

Improvekey-off function availabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent segments the power conversion function by introducing a dedicated key-off DCDC converter that operates independently from the main power train DCDC converter. This dedicated converter handles only key-off electrical loads, separating this function from the main propulsion power management system and eliminating the need for continuous 12V battery cycling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The key-off DCDC converter operates periodically only when key-off electrical loads require power, rather than remaining continuously active. This on-demand operation significantly reduces energy consumption compared to keeping the main DCDC converter continuously active, while still ensuring key-off functions are available when needed.

Inventive Principle:

Principle #19Periodic action

3Power

If the main DCDC converter is used for key-off loads, then power can be supplied, but overhead energy consumption increases and power is wasted

Engineering Contradiction:

Improvepower supply capabilityVSAvoidoverhead energy consumption

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent segments the power conversion function by introducing a dedicated key-off DCDC converter that operates independently from the main power train DCDC converter. This dedicated converter handles only key-off electrical loads, separating this function from the main propulsion power management system and eliminating the need for continuous 12V battery cycling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The key-off DCDC converter is sized and designed to handle only the partial power requirements of key-off electrical loads, rather than being oversized to handle all power train requirements. This right-sizing eliminates excessive overhead energy consumption that would occur if the main DCDC converter were used for small key-off loads.

Inventive Principle:

Principle #16Partial or excessive action

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 decreases battery drain on key-off power consumption, increases vehicle range, reduces weight and cost by eliminating the 12V battery, and enhances power conservation by using a smaller, more efficient conversion unit for key-off functions.

Implementation Method 1

one or more dedicated key-off conversion units down convert current from the battery to a lower voltage, such as 12V

Methodology Applied

Scientific EffectDCDC conversion: Electromagnetic Induction

Data Source

PatentEP4286202A1Dedicated DCDC conversion unit for supplying key-off electrical loads from the propulsion battery in a vehicle

Publication Date: 2023.12.06 VOLVO CAR CORP

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AI summary

A device enabling dedicated DCDC conversion for key-off electrical loads is described. According to one or more embodiments, a device is provided comprising a battery, one or more main conversion units coupled to the battery, and one or more dedicated key-off conversion units coupled to the battery and to one or more key-off electrical modules.