Vehicle Control Unit Diode Fault Detection Circuit

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Solution Overview

Problem

Existing control units for vehicles with idling stop systems face challenges in detecting open faults in diodes of back-up power source lines, which can lead to insufficient voltage during engine restart, particularly in unfavorable conditions, affecting safety devices like airbag control units.

Innovation Solution

A control unit with a redundancy circuit and fault detector that includes a main power source line, a back-up power source line, and a diode, where the back-up power source performs voltage compensation and is turned on after a predetermined time, allowing the fault detector to monitor the cathode voltage of the diode for open fault detection by comparing it to a threshold after the main power source is turned off.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a diode is used in the back-up power source line for redundancy, then the back-up power source can be activated when main power fails, but it becomes difficult to detect open faults in the diode due to common voltage at the cathode side

Engineering Contradiction:

Improveback-up power supply reliabilityVSAvoiddiode open fault detection difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The fault detection circuit performs preliminary detection of diode open faults by monitoring voltage during the transition period when the back-up power source is activated. This preliminary action allows detection before actual power failure occurs, resolving the contradiction by enabling fault detection while maintaining the diode's protective function.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A fault detection circuit is introduced as an intermediary component that monitors the voltage at the cathode side during the transition period. This intermediary enables indirect detection of diode status by observing voltage characteristics, solving the detection difficulty while preserving the redundancy circuit's reliability function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the back-up power source line is turned on immediately, then voltage compensation can occur faster, but the back-up power source may be damaged by inrush current

Engineering Contradiction:

Improvevoltage compensation speedVSAvoidback-up power source durability

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The back-up power source is preliminarily charged through a current limiting circuit before being activated. This preliminary charging action prepares the back-up source without subjecting it to damaging inrush current, enabling both fast response and durability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A current limiting circuit is implemented as a cushioning mechanism that restricts inrush current to the back-up power source during activation. This beforehand cushioning protects the back-up source from damage while still enabling timely voltage compensation when main power fails.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If the engine is restarted from an idling stop state, then the vehicle can resume driving quickly, but the voltage may become insufficient due to unfavorable conditions such as battery deterioration or cold temperature

Engineering Contradiction:

Improvevehicle restart speedVSAvoidvoltage sufficiency for safety devices

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The back-up power source is preliminarily charged and activated before the engine restart process completes. This preliminary action ensures that sufficient voltage is available during the transition period, preventing insufficient voltage conditions even in unfavorable environments while maintaining quick restart capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The back-up power source acts as a cushioning power supply that provides additional voltage support during engine restart. This beforehand cushioning compensates for voltage drops caused by battery deterioration or cold temperatures, ensuring reliable operation of safety devices during quick restart operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS9328711B2Control unit for vehicle

Publication Date: 2016.05.03 DENSO CORP

AI summary

In a control unit for a vehicle, a redundancy circuit includes a main power source line, a back-up power source line, and a diode. The back-up power source line performs a voltage compensation operation when a voltage of the main power source line is lower than a predetermined voltage. The back-up power source line is turned on when a predetermined period of time has elapsed after the main power source line is turned on. The back-up power source line is turned off when a predetermined period of time has elapsed after the main power source line is turned off. The diode is disposed on the back-up power source line. The fault detector detects an open fault of the diode when a voltage of a cathode of the diode is lower than a predetermined threshold within the predetermined period of time after the main power source line is turned off.