Inverter Power Control via Voltage and Current Sensing

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Solution Overview

Problem

Existing power conversion apparatuses that control inverter circuits based solely on current input fail to precisely account for voltage fluctuations, leading to inefficient operation and potential overheating, as they require conservative current thresholds to prevent overheating, thereby limiting output.

Innovation Solution

A power conversion apparatus that detects both current and voltage inputs to calculate a power value and performs droop control to reduce output when the power value exceeds a predetermined threshold, ensuring more precise control and efficient operation by directly addressing the heat generated by components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If output control is based on current value only, then the control method is simple, but the control precision is insufficient and operation efficiency is reduced

Engineering Contradiction:
Improvecontrol method complexityVSAvoidoutput control precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines current detection and voltage detection into a unified power-based control system. By merging these two detection functions and calculating power from both parameters, the system achieves more precise output control while maintaining reasonable complexity through integrated processing.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces simple current-based control with a power-based control system that calculates power from voltage and current measurements. This substitution enables more accurate thermal management and output control by directly monitoring the actual power consumption rather than relying on current alone.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If conservative current thresholds are used to prevent overheating, then component safety is improved, but output is limited and efficiency is reduced

Engineering Contradiction:
Improvecomponent safetyVSAvoidoutput efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements feedback control by continuously monitoring both voltage and current, calculating real-time power consumption, and adjusting the output accordingly. This feedback mechanism allows the system to operate closer to actual thermal limits rather than conservative thresholds, improving both safety and efficiency.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transitions from static current thresholds to dynamic power-based control. By continuously adjusting the output based on real-time power measurements, the system can adapt to varying operating conditions and maximize output within safe thermal limits rather than being constrained by fixed conservative thresholds.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If voltage fluctuations are not considered in control, then the control system is simpler, but heat generation is not accurately controlled

Engineering Contradiction:
Improvecontrol system complexityVSAvoidcomponent heat generation
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The patent replaces simple current monitoring with power-based control that incorporates both voltage and current measurements. This substitution enables accurate monitoring of actual power consumption and heat generation, allowing for precise thermal management that accounts for voltage fluctuations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2273662B1Power conversion device
Publication Date: 2020.01.08 DAIKIN INDUSTRIES LTD
  • EP2273662B1 patent drawingFigure 1
  • EP2273662B1 patent drawingFigure 2
  • EP2273662B1 patent drawingFigure 3

AI summary

The invention relates to a power conversion apparatus including a converter circuit and an inverter circuit. The invention allows more precise output control of the inverter circuit than a power conversion apparatus in which the output control is performed based on a current value only, thereby improving operation efficiency. A current sensor (17) detects input current of the inverter circuit (3), and a voltage sensor (15) detects input voltage of the inverter circuit (3). A power value calculator section (33) in an inverter microcomputer (30) obtains a power value based on the input current and the input voltage. The inverter microcomputer (30) and the control microcomputer (40) perform droop control of reducing the output of the inverter circuit (3) to make the power value smaller than a predetermined power value.