Capacitor Charging Control for Magnetic Actuators

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Solution Overview

Problem

Existing techniques for charging and monitoring capacitors used in magnetic actuator control mechanisms for medium or high voltage switchgear fail to efficiently charge the capacitors in minimum time, verify correct charge, detect faults, limit charging current, and prevent power supply tripping due to faults or errors, while also allowing capacitor reforming and generating alarms for anomalies.

Innovation Solution

A system comprising voltage and current regulators, a switch, and a converter to control the charging and monitoring of capacitors, allowing rapid charging, current limitation, fault detection, and capacitor reforming, with digital control of charging current and alarm generation for faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If conventional charging techniques are used, then the capacitor can be charged, but the charging time is excessive and the current is not limited, risking capacitor damage

Engineering Contradiction:
Improvecharging timeVSAvoidcapacitor safety
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent implements dynamic charging current control through a regulator that continuously adjusts the charging current based on real-time capacitor voltage feedback. The current starts high for rapid charging then automatically reduces as the capacitor approaches full charge, optimizing both charging speed and safety. This dynamic adjustment prevents thermal runaway while minimizing charging time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates a feedback mechanism where the capacitor voltage is continuously measured and fed back to the current regulator. This feedback loop enables the regulator to automatically adjust the charging current magnitude based on the actual charging state, ensuring the capacitor is charged efficiently without exceeding safe current limits that could cause damage.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If leakage current measurement is implemented, then capacitor faults can be detected, but false fault detection occurs leading to excessive unavailability

Engineering Contradiction:
Improvefault detection accuracyVSAvoidsystem availability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent monitors the evolution of charging current parameters over time during the charging process. Instead of relying on single-point leakage measurements that may be inaccurate, the system analyzes changes in current magnitude and timing characteristics throughout the charging cycle to detect genuine faults while filtering out transient anomalies that would cause false alarms.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system performs preliminary characterization of the capacitor's charging behavior during normal operation, establishing a baseline profile. This preliminary action enables the system to distinguish between normal variations in charging characteristics and actual fault conditions, reducing false fault detections and maintaining system availability.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If rapid charging is implemented, then charging time is reduced, but the charging current may exceed safe limits and damage the capacitor

Engineering Contradiction:
Improvecharging speedVSAvoidcapacitor thermal stress
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The charging system dynamically adjusts the current magnitude during the charging process. Initially, high current is applied for rapid charging when the capacitor voltage is low and thermal stress is minimal. As the capacitor voltage increases and approaches the target value, the current automatically reduces, preventing thermal runaway and damage while maintaining maximum charging speed throughout the process.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates protective measures in advance by implementing current limiting circuitry and monitoring mechanisms before charging begins. These precautions are built into the charging protocol to prevent harmful thermal stress from occurring in the first place, allowing rapid charging to proceed safely without risking capacitor damage.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

Enables capacitors to be charged within a fixed time, detects anomalies quickly, corrects faults when possible, and prevents damage by limiting charging current, ensuring safe operation and avoiding unnecessary tripping or capacitor destruction.

Implementation Method 1

a capacitor making it possible to supplying electrical power to the electromagnetic control device

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

an electromagnetic control device for moving the actuator from a first switching position to a second switching position

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2228813B1Medium or high voltage apparatus comprising a monitoring and charging device for a capacitor used for driving a magnetic actuator
Publication Date: 2017.08.09 SCHNEIDER ELECTRIC ENERGY FRANCE
  • EP2228813B1 patent drawingFigure 1
  • EP2228813B1 patent drawingFigure 2A~2D
  • EP2228813B1 patent drawingFigure 3

AI summary

The device has a regulator (10) whose set point input is connected to output of a voltage set point supply unit (12) and output is connected to input of a current set point supply unit (12 '). Another regulator (11) comprises a measurement input, a set point input and an output and regulates the charge current of a capacitor (C). The set point input of the latter regulator is connected to the output of the current set point supply unit. A switch (13) is located between a power supply (14) and a terminal of the capacitor and controlled by the output of the latter regulator. Independent claims are also included for the following: (1) a system for controlling a magnetic actuator in an average or high voltage apparatus (2) a method for charging and monitoring a capacitor that is used for controlling a magnetic actuator during discharge.