Dual-Inverter Power Converter Voltage Filtering for Overvoltage Detection

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Solution Overview

Problem

Conventional power converters face issues with wire impedance differences between inverters, leading to bus voltage fluctuations, increased risk of overvoltage detection malfunctions, and noise interference, which can cause incorrect voltage detection and apparatus failures.

Innovation Solution

The power converter includes separate voltage detection and drive signal generators for each inverter, with filter circuitries and time constants set based on wire impedances to suppress impedance differences, and uses different threshold values for anomaly detection to ensure reliable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If wire impedance is increased to reduce noise influence, then noise immunity is improved, but overvoltage detection responsiveness deteriorates

Engineering Contradiction:

Improvenoise influenceVSAvoidovervoltage detection responsiveness

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies different filter time constants to different voltage detection circuitries based on their respective wire impedances. Specifically, the first filter time constant is set longer than the second filter time constant when the first wire impedance is larger than the second wire impedance. This local differentiation allows each detection circuit to be optimized for its specific impedance characteristics, achieving both noise immunity and overvoltage detection responsiveness simultaneously.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If filter time constant is increased to suppress noise, then measurement stability is improved, but overvoltage detection speed deteriorates

Engineering Contradiction:

Improvevoltage detection accuracyVSAvoidovervoltage detection speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent changes the filter time constant parameter based on wire impedance characteristics. By setting the first filter time constant longer than the second filter time constant when the first wire impedance is larger, the system adapts the filtering strength to match the actual impedance conditions, achieving optimal balance between noise suppression and detection speed for each circuit.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If uniform protection threshold is used for all inverters, then device simplicity is improved, but detection accuracy deteriorates due to impedance differences

Engineering Contradiction:

Improveprotection circuitry configurationVSAvoidanomaly detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements different protection threshold values for different inverter circuits based on their wire impedance characteristics. The first protection threshold value differs from the second protection threshold value when wire impedances differ, allowing each circuit to have optimized protection settings that account for its specific impedance profile, thereby improving detection accuracy without excessive complexity.

Inventive Principle:

Principle #3Local quality

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

This configuration reduces the influence of wire impedance differences, enhancing the reliability and responsiveness of the power converter by preventing malfunctions and protecting components from overvoltage anomalies.

Implementation Method 1

a converter configured to rectify alternating-current power supplied from an alternating-current power supply

Methodology Applied

Scientific EffectRectification: Diode

Implementation Method 2

a main circuitry capacitor that is configured to smooth direct-current power output from the converter

Methodology Applied

Scientific EffectCapacitance filtering: Capacitance

Implementation Method 3

a first voltage detection circuitry configured to detect a voltage input to the first inverter and perform filtering of a detection value

Methodology Applied

Scientific EffectElectronic filtering: Filter (electronic)

Data Source

PatentUS20250373147A1Power converter and air conditioner

Publication Date: 2025.12.04 MITSUBISHI ELECTRIC CORP

AI summary

A power converter includes: a converter that rectifies alternating-current power; a first inverter and a second inverter; a first voltage detection circuitry that performs filtering of a detection value of a voltage input to the first inverter, and outputs the detection value as a first voltage detection value; a second voltage detection circuitry that performs filtering of a detection value of a voltage input to the second inverter, and outputs the detection value as a second voltage detection value; a first drive signal generator that performs, based on the first voltage detection value, operation of generating a drive signal for the first inverter and operation of protecting the first inverter; and a second drive signal generator that performs, based on the second voltage detection value, operation of generating a drive signal for the second inverter and operation of protecting the second inverter.