Switching Element Drive Control for Fast Overcurrent Detection

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Solution Overview

Problem

Conventional switching element current detection systems face challenges in accurately detecting currents due to sense resistance and capacitance variations, making it difficult to rapidly identify overcurrent or short-circuit conditions, which can lead to reduced element lifetime and increased complexity.

Innovation Solution

A drive control apparatus for switching elements that includes a drive circuit, a transient characteristic absorbing circuit, and a determination circuit, allowing for rapid detection of overcurrent or short-circuit states by absorbing transient characteristics and determining abnormal conditions without waiting for the completion of transient changes, thereby preventing continued current flow and reducing the required current capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional current detection is used with sense resistance and capacitance, then current monitoring is enabled, but transient characteristics cause detection inaccuracy and delay

Engineering Contradiction:

Improvecurrent detection accuracyVSAvoiddetection response time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The transient characteristic absorbing circuit is activated in advance during the turn-on period to preemptively eliminate transient effects before they interfere with accurate current detection. By preparing the absorption mechanism beforehand, the system achieves rapid accurate detection without waiting for transient characteristics to naturally decay.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A transient characteristic absorbing circuit is introduced as an intermediary component between the sense element and the detection system. This intermediary absorbs the harmful transient characteristics (capacitance effects, voltage spikes) while allowing the true current information to pass through, thereby resolving the contradiction between detection speed and accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If wait for transient characteristic completion before detection, then accurate measurement is possible, but element lifetime is reduced due to continued abnormal current flow

Engineering Contradiction:

Improvecurrent measurement accuracyVSAvoidswitching element lifetime

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The transient characteristics that normally cause detection errors and delays are converted into beneficial effects by the absorbing circuit. The circuit transforms harmful voltage spikes and capacitance effects into manageable signals that can be quickly processed, enabling both rapid detection and element protection simultaneously.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The transient characteristic absorbing circuit serves as a mediator that separates the harmful transient effects from the useful current information. By filtering out the transient noise while preserving the actual current signal, the system can make accurate protection decisions immediately without waiting for transient characteristics to settle, thereby extending element lifetime.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If additional correction circuits are added to improve detection accuracy, then measurement precision increases, but device complexity increases

Engineering Contradiction:

Improvecurrent detection precisionVSAvoidcircuit configuration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The transient characteristic absorbing function is merged with the existing current detection circuit rather than being implemented as a separate complex correction system. By combining multiple functions (transient absorption, current sensing, and protection detection) into a unified circuit architecture, the system achieves high detection precision without proportionally increasing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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

The solution enables rapid and accurate detection of overcurrent or short-circuit states, reducing the risk of element damage and allowing for a simpler, less expensive configuration that effectively limits the duration of abnormal current flow.

Implementation Method 1

a transient characteristic absorbing circuit that absorbs a transient characteristic of the sense element when the switching element is turned on

Methodology Applied

Scientific EffectCapacitance absorption: Capacitance

Data Source

PatentUS11095283B2Drive control apparatus for driving a switching element including a sense element

Publication Date: 2021.08.17 DENSO CORP

AI summary

A drive control apparatus for a switching element drives a switching element including a sense element, and includes a drive circuit that provides a gate driving signal to the switching element, a transient characteristic absorbing circuit that absorbs a transient characteristic of the sense element when the switching element is turned on, and a determination circuit that determines an overcurrent or a short-circuit state of the switching element from an output of the sense element.