Fuel Injector Drive Circuit Short Detection by Frequency Analysis

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Solution Overview

Problem

Existing fuel injector drive circuitry is prone to damage due to high frequency switching under shorted load conditions, which existing overcurrent mechanisms fail to detect reliably, leading to incomplete protection.

Innovation Solution

A High Frequency Switching Detection Module integrated into the ASIC monitors the frequency of high side drive signals, comparing it against pre-set thresholds to identify and immediately halt high frequency switching, providing comprehensive fault detection and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If high frequency switching is enabled in the High Side Drive, then the drive frequency capability is improved (up to 212KHz), but the reliability deteriorates under shorted load conditions causing FET damage

Engineering Contradiction:

Improvedrive frequencyVSAvoidFET durability under short conditions

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary detection of shorted load conditions by monitoring the High Side Drive enable signal frequency before damage occurs. The detection module continuously analyzes the BNK[x]_HS_EN signal, and when abnormal high frequency switching is detected, the system proactively shuts down the High Side Drive output FET to prevent damage, rather than waiting for failure to occur.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If existing overcurrent mechanisms are used, then some protection is provided, but detection precision is insufficient to reliably detect shorted load conditions

Engineering Contradiction:

Improveprotection capabilityVSAvoidshort condition detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary detection module that specifically monitors the High Side Drive enable signal (BNK[x]_HS_EN) frequency. This intermediary mechanism bridges the gap between the control system and the FET protection, providing specialized frequency-based detection that complements existing overcurrent mechanisms. The detection module acts as a mediator that translates enable signal characteristics into protective shutdown actions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3947947B1Method and circuitry to detect and prevent shorting in fuel injector drive circuitry

Publication Date: 2025.12.24 BORGWARNER US TECHNOLOGIES LLC

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AI summary

Drive circuitry for a fuel injector actuator, said drive circuitry including a High Side Drive portion and a Low Side Drive Portion, and including determination means to determine a short condition, said determination means adapted to perform a frequency analysis of a voltage(s) or a voltage signal at, or from, one or more points in the High Side Drive, and to determine if a faulty short conditions exists based on said analysis.