Parallel Switching Units for Motor Vehicle Battery Discharge Protection

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Solution Overview

Problem

Existing discharge protection devices for motor vehicle batteries are expensive and inflexible, requiring large, expensive components to handle maximum current loads without distinguishing between normal operation and standby modes, leading to unnecessary energy consumption.

Innovation Solution

The discharge protection device employs two parallel switching units with different holding currents, allowing control electronics to manage them based on load current magnitude, using a smaller holding current for standby mode and a larger one for normal operation, minimizing energy consumption and component size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single switching device is designed for maximum current of the electrical system, then it can handle all load conditions, but the device becomes large, expensive, and consumes excessive holding current in standby mode

Engineering Contradiction:
Improvecurrent handling capabilityVSAvoidholding current consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent divides the single switching device into two parallel switching units with different current ratings. The first switching unit is designed for maximum current handling during normal operation, while the second switching unit is designed for reduced current handling during standby mode. This segmentation allows the system to use only the appropriate switching unit for each operational state, reducing holding current consumption during standby while maintaining full current handling capability when needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic switching between two different switching units based on operational state. The control electronics automatically select which switching unit to activate - using the first switching unit during normal operation and the second switching unit during standby mode. This dynamic adaptation allows the system to optimize holding current consumption according to actual load conditions rather than maintaining fixed high-capacity switching throughout.

Inventive Principle:
Principle #15Dynamics

2Use of energy by stationary object

If a bistable relay is used to prevent holding current consumption, then energy is saved, but the device becomes expensive and must be oversized for maximum current

Engineering Contradiction:
Improveholding currentVSAvoidcomponent cost and availability
Core Design Contradiction:
Use of energy by stationary objectVSEase of manufacture

Solution Approach 1:

Instead of using one expensive oversized bistable relay, the patent segments the switching function into two standard relays with different current ratings. This allows the use of affordable, readily available standard components rather than requiring a single expensive custom-designed bistable relay capable of handling maximum current in all conditions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the current rating parameter of the switching units by providing two different switching units with different maximum current capabilities. This parameter differentiation allows optimization of each unit for its specific operational context, making the overall system more cost-effective while maintaining energy efficiency.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the switching device is designed for maximum current, then it can handle any load condition, but the device size and cost increase unnecessarily for standby operation

Engineering Contradiction:
Improveload condition handlingVSAvoidcomponent size
Core Design Contradiction:
Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The patent segments the switching capability into two specialized units - one optimized for high current during normal operation and another optimized for low current during standby. This segmentation provides adaptability to different load conditions without requiring a single oversized component, thereby reducing the overall size and weight of the switching device assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent achieves multi-functionality by providing two switching units that together can handle both normal operation and standby mode requirements. Rather than designing a single device to universally handle all conditions (which would be oversized), the system uses multiple specialized units that collectively provide universal adaptability across different operational states.

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

Data Source

PatentEP2221941B1Discharge protection device
Publication Date: 2012.11.07 DELPHI TECHNOLOGIES INC
  • EP2221941B1 patent drawingFigure 1~2

AI summary

The protection device has a switching device (16) controlled by a control electronics unit (14). The switching device is arranged between a battery (12) and electrical consumers that are attached to a power supply system (18). The switching device includes two switching units (20, 22) that are arranged parallel to each other, where one of the switching units comprises a FET i.e. P-channel-FET. The switching units are designed such that the switching units are controlled by the control electronics unit at high and low load currents, respectively in a closed condition.