Electric Power Inverter Radial Current Paths

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Solution Overview

Problem

Conventional electric power inverters for electrical machines face issues such as heat generation, electromagnetic interference, and mechanical failure due to vibrations, which lead to solder joint breakage and increased height, affecting their reliability and efficiency.

Innovation Solution

The electric power inverter design features a stacked configuration of capacitor and semiconductor boards with radial current paths, mechanical dissociation of capacitors, and a thermally conductive heat exchanger plate to reduce parasitic resistances and inductances, enhance cooling, and prevent mechanical stress on soldered contacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capacitors are soldered to the capacitor board with rigid wire connections, then electrical connectivity is ensured, but the soldered joints and wire connections are prone to breaking due to vibrations and oscillations

Engineering Contradiction:
Improvereliability of electrical connectionsVSAvoidstrength of soldered joints
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The capacitor board is divided into multiple separate capacitor units, each with its own mounting structure. This segmentation allows each capacitor to be independently secured to the capacitor board, distributing the mechanical stress and reducing the risk of connection failure due to vibrations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The capacitor housing is integrated with the mounting structure, combining the electrical component housing and the mechanical mounting function into a single unified structure. This merging eliminates the need for separate mounting brackets and reduces the number of potential failure points in the connection system.

Inventive Principle:
Principle #5Merging (Combining)

2Quantity of substance

If capacitors are arranged with substantial height, then adequate space for electrical components is provided, but the overall height of the electric power inverter is disadvantageously increased

Engineering Contradiction:
Improvespace for electrical componentsVSAvoidoverall height of inverter
Core Design Contradiction:
Quantity of substanceVSLength of stationary object

Solution Approach 1:

The capacitor units are arranged in a planar configuration on the capacitor board rather than stacking them vertically. This dimensional change from vertical to horizontal arrangement allows adequate space for electrical components while maintaining a compact overall height of the inverter.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If current paths on the capacitor board are extended, then adequate space for component arrangement is achieved, but parasitic resistances and inductances increase

Engineering Contradiction:
Improvespace for component arrangementVSAvoidparasitic resistances and inductances
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The current paths on the capacitor board are designed with curved traces rather than straight lines, optimizing the electrical pathways to minimize inductance while accommodating the planar arrangement of capacitor units. The curved paths reduce sharp angles and discontinuities that would increase parasitic effects.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 improves the reliability and efficiency of the electric power inverter by reducing parasitic resistances and inductances, protecting soldered contacts from breakage, and maintaining a compact form factor while effectively cooling the components.

Implementation Method 1

a thermally conductive heat exchanger plate to reduce parasitic resistances and inductances, enhance cooling

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3609067B1Electric power inverter
Publication Date: 2022.08.31 MAHLE INT GMBH
  • EP3609067B1 patent drawingFigure 1
  • EP3609067B1 patent drawingFigure 2~3
  • EP3609067B1 patent drawingFigure 4~6

AI summary

The invention relates to an electric power inverter (10) for an electrical machine of an electrically powered drive system. The electric power inverter (10) incorporates a capacitor board (20) having a plurality of capacitors (21), and more than one semiconductor board (30) each having a plurality of power semiconductors (31), which are mutually stacked in a stacking direction (11), with a clearance, in a stack formation (12), and are electrically interconnected. The plurality of capacitors (21) are arranged on the capacitor board (20) in the stacking direction (11), and are fitted to a side thereof facing the semiconductor boards (30). The plurality of capacitors (21) are arranged on the capacitor board (20) to form more than one open location space (23) between the capacitors (21) on the capacitor board (20), each location space (23) positioned to accommodate one of the respective semiconductor boards (30), and the respective semiconductor board (30) is arranged within the respective location space (23), with a clearance to the capacitor board (20). According to the invention, at least some capacitors (21) are arranged in the middle of the capacitor board (20) and the semiconductor boards (30) are all arranged on the edge of the capacitor board (20), so that current paths on the capacitor board (20) extend generally radially from the middle to the edge of the capacitor board (20). The invention also relates to an electrical machine having said electric power inverter (10).