Power Converter Maintenance Timing Using Reserve Module Failure Rates

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Solution Overview

Problem

Existing methods for determining the maintenance schedule of electrical power converters often result in premature maintenance, leading to unnecessary costs and downtime, as they do not accurately assess the availability of reserve modules and the frequency of module failures.

Innovation Solution

A method and monitoring device that determine the time until the next maintenance by calculating the frequency of module failures and comparing it with the number of available reserve modules, using either real-time data or historical experience frequencies to ensure maintenance is only performed when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If maintenance is performed at regular intervals, then the power converter is maintained proactively, but maintenance is performed too early leading to unnecessary costs and downtime

Engineering Contradiction:
Improvemaintenance reliabilityVSAvoiddowntime
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The maintenance schedule transitions from static regular intervals to dynamic intervals based on actual module failure frequency. The control device continuously monitors defective modules and adjusts the maintenance timing dynamically, extending the interval when failure rate is low and shortening it when failure rate increases, thus avoiding unnecessary early maintenance while ensuring timely intervention when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback by continuously monitoring the frequency of defective modules and using this information to determine the optimal maintenance time. The control device receives data about module failures, calculates the failure frequency, and adjusts the maintenance schedule accordingly, creating a closed-loop system that adapts to actual system conditions rather than following a predetermined schedule.

Inventive Principle:
Principle #23Feedback

2Loss of energy

If maintenance is postponed to save costs, then costs and downtime are reduced, but the power converter may fail when reserve modules are depleted

Engineering Contradiction:
Improvemaintenance costsVSAvoidpower converter reliability
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The system performs preliminary action by determining the optimal maintenance time in advance based on the current number of reserve modules and the observed failure frequency. The control device calculates how long the reserve modules will last at the current failure rate and schedules maintenance before reserve modules are depleted, preventing converter failure while avoiding unnecessary early maintenance.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The maintenance decision is based on changing parameters - specifically the number of reserve modules and the failure frequency of modules. As these parameters change over time, the optimal maintenance time is recalculated. The system monitors changes in failure frequency and adjusts the maintenance schedule accordingly, maintaining reliability while optimizing costs.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of stationary object

If the number of reserve modules is increased, then the power converter can operate longer without maintenance, but the device complexity and initial costs increase

Engineering Contradiction:
Improveoperation duration without maintenanceVSAvoidconverter complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The system segments the maintenance decision into two independent components: the number of reserve modules (fixed hardware parameter) and the failure frequency monitoring (dynamic software parameter). By separating these, the system can maintain a reasonable number of reserve modules without excessive complexity, using intelligent monitoring and calculation to extend operational duration rather than relying solely on having many more reserve modules.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control device performs self-service by automatically monitoring module failures, calculating failure frequency, and determining optimal maintenance timing without external intervention. This intelligent self-monitoring allows the system to maximize the utilization of available reserve modules, extending operational duration between maintenances without adding physical complexity or additional hardware components.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3394975B1Method for determining a time duration
Publication Date: 2024.05.22 SIEMENS ENERGY GLOBAL GMBH & CO KG
  • EP3394975B1 patent drawingFigure 1
  • EP3394975B1 patent drawingFigure 2~3
  • EP3394975B1 patent drawingFigure 4~5

AI summary

The invention relates to a method for determining a period until the next maintenance of an electrical power converter which has a multiplicity of identical modules (1_1, 1_2, 1_3) each having at least two electronic switching elements (202, 206) and an electrical energy store (210). A subset of the modules are reserve modules (1_n+1, 1_n+2), with the result that, if a defective module (1_3) occurs, one of the reserve modules (1_n+1) can be used instead of the defective module (1_3). In the method, the frequency of the occurrence of defective modules is determined (502), and the period until the next maintenance is determined by comparing the number of reserve modules available at the determination time with the frequency of the occurrence of defective modules (506).