Power Converter Second Reactor Overcurrent Suppression

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Solution Overview

Problem

Power converters with full bridge circuits often experience overcurrent due to deviations in switching timing caused by vertical offset and phase shift in detection voltage, leading to short circuits and potential overcurrent flow.

Innovation Solution

Incorporating a second reactor positioned between AC side terminals and connection points within the full bridge circuit, which uses its inductance to suppress or reduce overcurrent by aligning current changes with the AC power supply's polarity changes, thereby preventing short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a full bridge circuit is used for power conversion, then power conversion efficiency is improved, but switching timing deviation causes overcurrent and short circuits

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidswitching timing accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces a detection voltage correction unit as an intermediary component that processes the detection voltage to generate corrected detection voltage. This correction unit compensates for vertical offset and phase shift errors, serving as a mediator between the imperfect detection system and the switching control system, thereby eliminating switching timing deviation while maintaining full bridge circuit operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback mechanism where the detection voltage is continuously monitored, corrected based on identified errors (vertical offset and phase shift), and the corrected voltage is fed back to the switching control unit. This closed-loop feedback ensures accurate switching timing by continuously compensating for detection errors, resolving the contradiction between maintaining full bridge operation and achieving precise switching timing

Inventive Principle:

Principle #23Feedback

2Device complexity

If detection voltage is used to determine switching timing, then switching control is simplified, but vertical offset and phase shift cause timing deviation

Engineering Contradiction:

Improveswitching control complexityVSAvoiddetection voltage accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The detection voltage correction unit acts as an intermediary that processes the raw detection voltage without complicating the overall control structure. It specifically targets and corrects vertical offset and phase shift errors, maintaining simplicity in the switching control logic while improving measurement precision through dedicated correction processing

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by adjusting the detection voltage parameters (correcting vertical offset and phase shift) to eliminate timing deviation. By modifying these specific parameters of the detection voltage, the system maintains simple switching control logic while achieving accurate timing determination

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If switching timing is synchronized with detection voltage zero-crossing, then control is simplified, but polarity change timing is deviated

Engineering Contradiction:

Improveswitching control easeVSAvoidswitching timing deviation

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The system uses feedback from the detection voltage correction unit to identify and compensate for timing deviation. By continuously monitoring the relationship between detection voltage zero-crossing and actual polarity changes, the correction unit adjusts the switching timing through corrected detection voltage, maintaining ease of operation while eliminating time loss due to synchronization errors

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by pre-correcting the detection voltage for vertical offset and phase shift errors before it is used for switching timing determination. This preliminary correction ensures that the subsequent switching operation is based on accurate timing information, eliminating the need for complex real-time adjustments while maintaining synchronization accuracy

Inventive Principle:

Principle #10Preliminary action

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 second reactor effectively reduces overcurrent flow even when switching timing deviates from actual voltage polarity changes, enhancing the stability and efficiency of the power converter.

Implementation Method 1

Methodology Applied

Scientific EffectInductance: Inductor

Data Source

PatentUS11258351B2Power converter

Publication Date: 2022.02.22 DENSO CORP

AI summary

A control unit determines a polarity of an actual voltage value of an AC power supply if it is either positive or negative based on a detection voltage thereof detected by the voltage detector. The control unit alternately actuates a set of a first switch and a fourth switch and another set of the second switch and a third switch each time when it is determined that the polarity of the actual voltage value of the AC power supply changes. A second reactor is disposed at at least one of first and second positions. The first position is located between a first AC side terminal and a connection point located between the first switch and the second switch. The second position is located between a second AC side terminal and a connection point located between the third switch and the fourth switch.