Inverter DC Bus Filtering and Capacitor Discharge for Heat and EMI

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Solution Overview

Problem

Existing inverters face issues with premature degradation, undesirable complexity, over-temperature conditions, and undesirable vibrations in bus bars, particularly in electric vehicles and solar installations.

Innovation Solution

The inverter assembly includes a phase-control chamber with a DC link capacitor connected to a control circuit board via multiple connectors and a DC chamber with a ferrite filter fixed to a DC bus bar via a support component, utilizing a compliant pad to reduce vibration and electromagnetic interference, and a discharge resistor to manage thermal conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bus bars are used to electrically connect the capacitor to the control circuit board, then electrical connection is achieved, but over-temperature conditions and undesirable vibrations occur in the bus bars

Engineering Contradiction:

Improveconnector reliabilityVSAvoidbus bar temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent introduces a connector as an intermediary component between the bus bar and the control circuit board. This connector serves as a mediator that reduces the thermal and vibrational stress transferred to the bus bar, thereby preventing over-temperature conditions and undesirable vibrations while maintaining electrical connection reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the electrical connection system into distinct components: the bus bar, the connector, and the control circuit board. By dividing the connection path into separate segments, the system can isolate and manage thermal and vibrational stresses in each component individually, preventing the propagation of these adverse effects throughout the entire system.

Inventive Principle:

Principle #1Segmentation

2Volume of moving object

If all internal circuitry is positioned in a single housing enclosure, then device compactness is achieved, but electromagnetic interference increases

Engineering Contradiction:

Improveinverter sizeVSAvoidelectromagnetic interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent divides the inverter housing into multiple separate chambers or enclosures, each housing different internal circuitry components. This spatial segmentation allows electromagnetic interference to be contained within specific chambers while preventing it from affecting other sensitive components, thereby reducing overall EMI without significantly increasing the total device volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces EMI shielding structures and filtering components as intermediaries between different circuitry sections. These intermediary elements act as barriers that block or attenuate electromagnetic interference while allowing the compact housing design to be maintained, thus reducing EMI without requiring a larger enclosure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If discharge resistor is integrated into the control circuit board, then space efficiency is improved, but thermal management becomes problematic

Engineering Contradiction:

Improveinverter volumeVSAvoiddischarge resistor temperature

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The patent extracts the discharge resistor from the control circuit board and positions it in a separate location within the inverter housing. This extraction allows the discharge resistor to be placed in an area with better thermal dissipation characteristics, such as near heat sinks or in chambers with improved airflow, thereby managing its thermal conditions while still maintaining overall space efficiency in the inverter design.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces thermal management intermediaries such as heat sinks, thermal pads, or cooling channels between the discharge resistor and the surrounding environment. These intermediary thermal management components facilitate heat dissipation from the discharge resistor, allowing it to be positioned in a compact configuration while preventing overheating.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This design enhances inverter longevity, reduces electromagnetic interference, and improves thermal management, leading to increased space efficiency and reduced complexity.

Implementation Method 1

the ferrite filter allows the amount of electromagnetic interference (EMI) in the DC chamber to be reduced

Methodology Applied

Scientific EffectElectromagnetic interference filtering: Absorption (EM radiation)

Implementation Method 2

The compliant pad reduces the amount vibration transferred to the DC bus bar assembly

Methodology Applied

Scientific EffectVibration damping: Damping

Implementation Method 3

the discharge resistor may be configured to discharge the DC link capacitor when the inverter assembly is turned off

Methodology Applied

Scientific EffectResistive heating: Joule Heating

Data Source

PatentUS12375008B2Inverter with capacitor discharge and DC bus filtering

Publication Date: 2025.07.29 DANA TM4 INC

AI summary

An inverter assembly including a phase-control chamber and a direct current (DC) chamber. The phase-control chamber includes a direct current (DC) link capacitor electrically connected a control circuit board via multiple connectors. The DC chamber includes a ferrite filter fixed to a DC bus bar via a support component.