Power Converter Pulse-Width Limiter for Overheating Prevention

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Solution Overview

Problem

Conventional power converters face overheating failures due to malfunctioning error amplifiers or comparators, and struggle to immediately adjust output voltage when input voltage increases rapidly, leading to unintended output voltage increases.

Innovation Solution

A power converter with a pulse-width limiter that adjusts the drive signal based on input and output voltages, preventing overheating by limiting pulse width even if reset signal generation fails, and immediately suppressing output voltage increases during rapid input voltage changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the error amplifier, comparator and RS flip-flop adjust the drive signal to suppress output voltage increase, then the output voltage is stabilized, but the response delay prevents immediate adjustment when input voltage rapidly increases

Engineering Contradiction:

Improveoutput voltage stabilityVSAvoidresponse speed to input voltage changes

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The pulse-width limiter pre-establishes a maximum pulse width threshold based on the relationship between input and output voltages. When the input voltage rapidly increases, this pre-set limit immediately constrains the drive signal pulse width without requiring sequential processing through the error amplifier, comparator, and RS flip-flop, thereby achieving immediate response while maintaining output voltage stability.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the reset signal generation components function normally, then the drive signal is properly controlled, but component failure or malfunction causes the switch to remain on and overheat

Engineering Contradiction:

Improvedrive signal control reliabilityVSAvoidswitch overheating due to component failure

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The pulse-width limiter establishes a safety threshold for the drive signal pulse width based on the input and output voltage relationship. This pre-set limit acts as a protective barrier that automatically constrains the switch conduction time even when the reset signal generation components fail or malfunction, preventing the switch from remaining on indefinitely and avoiding overheating damage.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS8994353B2Power converter with a pulse-width limiter that limits a drive signal pulse width according to the input voltage

Publication Date: 2015.03.31 DENSO CORP

AI summary

A power converter includes a control circuit provided with a set signal generator, a current command generator, a reset signal generator, a drive signal generator, and a pulse-width limiter. The set signal generator generates a set signal at every predetermined cycle. The current command generator generates a current command based on an output voltage command and an output voltage. The reset signal generator generates a reset signal based on an input current and the generated current command. The drive signal generator generates a drive signal which turns on in synchronization with the generated set signal to turn on a switching element and which turns off in synchronization with the subsequently generated reset signal to turn off the switching element. The pulse-width limiter limits a pulse-width of the drive signal according to an input voltage and the output voltage, or according to the input voltage and the output voltage command.