Inverter Capacitor Connection Testing for High-Voltage Reliability

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Solution Overview

Problem

Existing systems lack the ability to effectively test capacitors in high voltage circuits, such as inverters for electric vehicles, after they have been deployed, which can lead to disconnection or failure due to environmental factors, resulting in system performance degradation.

Innovation Solution

A testing circuit is implemented within the inverter system, utilizing a voltage divider, voltage detectors, and controllers to monitor capacitor connections and functionality by measuring voltages at different thresholds, allowing for real-time detection of disconnected or faulty capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capacitors are used in high voltage circuits exposed to environmental factors, then the system can operate in rugged environments, but the capacitors may detach or fail resulting in open circuits and system performance degradation

Engineering Contradiction:
Improvecapacitor connection reliabilityVSAvoidenvironmental factors (heat, cold, humidity, impact)
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The testing circuit performs preliminary detection of capacitor connections and functionality before failures occur. The voltage detector continuously monitors capacitor status, enabling early identification of detachment or failure conditions caused by environmental factors, allowing preventive maintenance or system shutdown before performance degradation occurs.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If existing testing systems are used, then basic capacitor testing can be performed, but they lack the ability to effectively test capacitors in high voltage circuits after deployment

Engineering Contradiction:
Improvecapacitor status detection accuracyVSAvoidpost-deployment testing capability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent introduces a testing circuit as an intermediary system between the high voltage inverter circuit and the detection mechanism. This testing circuit includes voltage dividers and detectors that safely interface with high voltage capacitors, enabling precise measurement of capacitor status without directly exposing the detection system to dangerous high voltage conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a testing circuit is implemented to monitor capacitor connections, then real-time detection of disconnected or faulty capacitors is enabled, but the device complexity increases

Engineering Contradiction:
Improveinverter system reliabilityVSAvoidtesting circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The testing circuit is designed to perform multiple functions: detecting capacitor disconnection, measuring capacitor functionality, and providing early failure warnings. By consolidating these detection capabilities into a single integrated testing circuit rather than separate systems, the patent achieves high reliability monitoring while minimizing the increase in overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 continuous monitoring and automatic detection of capacitor disconnection or failure in high voltage circuits, ensuring the inverter system operates reliably even in rugged environments.

Implementation Method 1

a voltage divider including resistors; a voltage detector configured to measure a voltage at the voltage divider

Methodology Applied
Scientific EffectVoltage divider: Ohm's Law

Implementation Method 2

a first capacitor connected in series with a second capacitor; Circuits that use capacitors may be exposed to environmental factors

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP4650794A1Systems and methods for testing capacitors in an inverter
Publication Date: 2025.11.19 BORGWARNER US TECHNOLOGIES LLC
  • EP4650794A1 patent drawingFigure 1
  • EP4650794A1 patent drawingFigure 2
  • EP4650794A1 patent drawingFigure 3

AI summary

Disclosed techniques relate to a system for testing a capacitor. An example system includes an inverter to convert DC power from a battery to AC power to drive a motor. The inverter includes a noise filter including a first capacitor connected in series with a second capacitor and a testing circuit configured to test one or more of the first capacitor or the second capacitor. The testing circuit includes a voltage divider including resistors; a voltage detector configured to measure a voltage at the voltage divider; a switch configured to connect the noise filter to the voltage divider; and one or more controllers configured to control an operation of the switch to connect the noise filter to the voltage divider, and to determine, from an output of the voltage detector, whether one or more of the first capacitor or the second capacitor are connected to the noise filter.