Power Conversion Device Step-Up Unit Insulation Diagnosis

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Solution Overview

Problem

Existing power conversion devices require a large and costly step-up unit for confirming soundness before interconnection with a DC power supply, due to inefficiencies in AC/DC converters when load is low, leading to increased size and cost.

Innovation Solution

A power conversion device with a capacitor on the DC power supply side and a step-up unit that generates voltage for insulation diagnosis, reducing the need for a large step-up unit by charging the capacitor for both insulation diagnosis and pre-charging, thereby minimizing size and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the AC/DC converter is operated to step up voltage for insulation diagnosis, then the voltage can be increased, but the device size and cost increase due to low efficiency at low load

Engineering Contradiction:

Improvevoltage outputVSAvoidstep-up unit size

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent divides the voltage generation function into two separate units: a step-up unit for generating high voltage insulation diagnosis voltage, and an AC/DC converter for normal power conversion. This segmentation allows the step-up unit to be sized appropriately for insulation diagnosis only, rather than requiring the AC/DC converter to handle both insulation diagnosis and normal operation, thus reducing the step-up unit size and cost.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines the insulation diagnosis voltage generation and capacitor charging functions into a single step-up unit. The step-up unit generates high voltage for insulation diagnosis and simultaneously charges the capacitor, eliminating the need for the AC/DC converter to operate at low load for insulation diagnosis purposes.

Inventive Principle:

Principle #5Merging (Combining)

2Power

If the AC/DC converter is operated for insulation diagnosis, then voltage can be stepped up, but energy loss increases due to low load operation

Engineering Contradiction:

Improvevoltage outputVSAvoidconverter loss

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent segments the voltage generation functions by dedicating the step-up unit specifically to insulation diagnosis voltage generation. This allows the AC/DC converter to operate only at efficient load levels for normal power conversion, while the step-up unit handles the low-load insulation diagnosis function, thereby minimizing overall energy loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The step-up unit acts as an intermediary device that generates the high voltage needed for insulation diagnosis without requiring the AC/DC converter to operate inefficiently. The step-up unit mediates between the power source and the insulation diagnosis requirement, enabling voltage step-up while avoiding the energy losses associated with low-load AC/DC converter operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If a large step-up unit is used for insulation diagnosis, then sufficient voltage can be generated, but the cost increases

Engineering Contradiction:

Improveinsulation diagnosis voltageVSAvoidmanufacturing cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent segments the voltage generation requirements by creating a dedicated step-up unit that is sized only for insulation diagnosis voltage generation, rather than requiring an oversized AC/DC converter to handle both insulation diagnosis and full-power operation. This segmentation allows for a more cost-effective step-up unit design that meets only the insulation diagnosis requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a step-up unit that is designed specifically for the temporary insulation diagnosis function rather than for continuous operation. This allows the use of simpler, less expensive components that are adequate for the short-duration insulation diagnosis task, reducing overall manufacturing cost while still achieving the required voltage output.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 achieves size and cost reduction of the step-up unit, reducing losses and enabling efficient soundness confirmation before interconnection, while also suppressing inrush currents and preventing failures.

Implementation Method 1

a capacitor provided on the DC power supply side of the AC/DC converter and storing the DC power

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the step-up unit generates voltage for insulation diagnosis on the basis of insulation diagnosis reference voltage, and applies the voltage for insulation diagnosis to the DC power supply side of the AC/DC converter, to charge the capacitor

Methodology Applied

Scientific EffectElectrical voltage generation:

Data Source

PatentUS10256713B2Power conversion device and method for controlling power conversion device

Publication Date: 2019.04.09 MITSUBISHI ELECTRIC CORP

AI summary

A power conversion device which converts power between a power grid and a DC power supply, includes: AC/DC converters for performing conversion from AC power to DC power or from DC power to AC power between the power grid and the DC power supply; a capacitor provided on the DC power supply side of the AC/DC converters and storing DC power; and a step-up unit for charging the capacitor.