Converter Circuit Self-Test Using Temporal Current Monitoring

Solution Overview

Problem

Existing electrical converter circuits, particularly in safety-critical applications like LED vehicle lighting, face economic and spatial disadvantages due to the need for additional measuring components to ensure plausibility of current control, which is essential for compliance with safety standards like ASIL-B.

Innovation Solution

A self-test method for electrical converter circuits that utilizes a control device to measure the temporal profile of electrical operating variables, such as current intensity, over a measurement cycle, using a counter to detect time and determine if the operating variable remains within a predetermined reference interval, thereby assessing component functionality without requiring additional measuring circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an additional simple measuring component is provided in the converter circuit to check current intensity plausibility, then the safety compliance and plausibilization capability are improved, but the cost and space occupation increase

Engineering Contradiction:

Improvesafety complianceVSAvoidcomponent quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control device's existing components (counter, comparator, timing circuitry) are made multi-functional by using them for both normal converter operation control and for self-test/plausibility checking of the current control. The counter that normally tracks switching cycles is also used to measure the time duration for current rise, and the comparator that normally controls switching is also used to detect when current reaches threshold values for test evaluation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The converter circuit performs its own self-test and plausibility checking using its existing control device components without requiring external measuring components. The control device monitors its own operation by detecting the time profile of the current through existing circuitry, enabling the system to self-verify its safety-critical functions.

Inventive Principle:

Principle #25Self-service

2Reliability

If an additional simple measuring component is provided in the converter circuit to check current intensity plausibility, then the safety compliance and plausibilization capability are improved, but the manufacturing cost increases

Engineering Contradiction:

Improvesafety complianceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The control device's existing components (counter, comparator, timing circuitry) are made multi-functional by using them for both normal converter operation control and for self-test/plausibility checking of the current control. The counter that normally tracks switching cycles is also used to measure the time duration for current rise, and the comparator that normally controls switching is also used to detect when current reaches threshold values for test evaluation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The converter circuit performs its own self-test and plausibility checking using its existing control device components without requiring external measuring components. The control device monitors its own operation by detecting the time profile of the current through existing circuitry, enabling the system to self-verify its safety-critical functions.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If the measurement cycle uses a fixed time duration, then the measurement precision and simplicity are improved, but the adaptability to different operating conditions decreases

Engineering Contradiction:

Improvemeasurement simplicityVSAvoidoperating condition adaptability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The measurement cycle duration is made dynamic rather than fixed. The measurement automatically adapts to different operating conditions by detecting when the current reaches a predetermined threshold value. This allows the measurement time to vary based on actual circuit behavior while maintaining precise measurement through the counter's ability to accurately time any duration.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The measurement process uses feedback from the current threshold detection to determine when to end the measurement cycle. The comparator continuously monitors the current and provides feedback to the counter to stop timing when the threshold is reached, creating an adaptive measurement system that responds to actual circuit conditions.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11226377B2Method for carrying out a self-test of an electrical converter circuit, and converter circuit and vehicle luminaire

Publication Date: 2022.01.18 CONTINENTAL AUTOMOTIVE TECHNOLOGIES GMBH

AI summary

A method carries out a self-test of an electrical converter circuit, by use of a control device, proceeding from a known operating point at which a predetermined electrical operating variable has a predetermined starting value, a measurement cycle is begun by the converter circuit being operated. It is additionally provided that the time since the starting of the measurement cycle is detected, and the electrical operating variable and the time constitute two monitoring variables of the self-test. The measurement cycle is ended if one of the two monitoring variables satisfies an ending criterion. A test value is then formed from a measurement value of the other of the two monitoring variables at the end of the measurement cycle and a check is made to ascertain whether the test value lies outside a predetermined reference interval. If so an error signal is generated.