Unified Leakage Current Calculation for Inverter Systems

Solution Overview

Problem

Existing leakage current calculation devices require different configurations based on the presence or absence of an inverter, making them inconvenient for facilities where inverters are added or removed for energy-saving purposes, as they need to be changed accordingly to accurately measure ground insulation resistance component leakage current.

Innovation Solution

A device and method that measure line voltages, calculate ground voltages, extract frequency components, determine phase differences, and assess whether an inverter is inserted, allowing for precise calculation of ground insulation resistance component leakage current regardless of inverter presence, using a unified calculation procedure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If different leakage current calculation devices are used depending on the presence or absence of an inverter, then measurement precision is improved, but device complexity and ease of operation deteriorate

Engineering Contradiction:

Improveground insulation resistance component leakage current measurement precisionVSAvoiddevice configuration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The leakage current calculation device incorporates multiple calculation procedures (first procedure for systems without inverters, second procedure for systems with inverters) within a single device. The insertion determination unit automatically detects whether an inverter is present and selects the appropriate calculation procedure, making one device universally applicable to both inverter and non-inverter systems while maintaining measurement precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The device dynamically adapts its calculation method based on the detected system configuration. The insertion determination unit monitors the power system and automatically switches between the first calculation procedure (for direct connection systems) and the second calculation procedure (for inverter-connected systems), allowing the device to optimize its operation for the current system state without requiring manual reconfiguration.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If different leakage current calculation devices are used depending on the presence or absence of an inverter, then measurement precision is improved, but ease of operation worsens

Engineering Contradiction:

Improveground insulation resistance component leakage current measurement precisionVSAvoiddevice operation convenience

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The leakage current calculation device performs self-diagnosis through the insertion determination unit, which automatically detects whether an inverter is inserted in the power system. Based on this automatic detection, the device autonomously selects and executes the appropriate calculation procedure without requiring user intervention or manual configuration, thereby maintaining high measurement precision while ensuring ease of operation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The device dynamically adapts its calculation method based on the detected system configuration. The insertion determination unit monitors the power system and automatically switches between the first calculation procedure (for direct connection systems) and the second calculation procedure (for inverter-connected systems), allowing the device to optimize its operation for the current system state without requiring manual reconfiguration.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If a unified leakage current calculation device is used for both inverter and non-inverter systems, then adaptability is improved, but measurement precision may deteriorate

Engineering Contradiction:

Improveadaptability to different system configurationsVSAvoidground insulation resistance component leakage current measurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The leakage current calculation device divides the calculation process into two distinct procedures: the first calculation procedure for systems without inverters and the second calculation procedure for systems with inverters. The insertion determination unit automatically identifies which procedure to use based on the presence or absence of an inverter, ensuring that each specific system type receives the optimized calculation method designed for it, thereby maintaining high measurement precision across different configurations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The device dynamically adapts its calculation method based on the detected system configuration. The insertion determination unit monitors the power system and automatically switches between the first calculation procedure (for direct connection systems) and the second calculation procedure (for inverter-connected systems), allowing the device to optimize its operation for the current system state without requiring manual reconfiguration.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11009559B2Leakage current calculation method

Publication Date: 2021.05.18 OMRON CORP

AI summary

An insertion determination unit (16) for precisely calculating a ground insulation resistance component of a leakage current regardless of the presence or absence of an inverter determines whether an inverter (3) is inserted between a commercial power system (2) and a three-phase motor (5). A resistance component leakage current calculation unit (18) calculates a ground insulation resistance component of a leakage current on the basis of a calculation procedure corresponding to the result of the above determination.