Integrated Motor-Inverter Layout for Compact Cooling and Wiring

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Solution Overview

Problem

Conventional electric power units face challenges in compact packaging due to the mismatched shapes of AC electric motors and inverters, leading to increased size and inefficient cooling, along with the need for numerous connectors and cables.

Innovation Solution

The electric power unit integrates a power assembly and control assembly within a common enclosure on the longitudinal side and end of the AC electric motor housing, with a cooling jacket surrounding the stator, reducing the overall size and eliminating the need for extensive wiring by using AC power busbars and sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the inverter is mounted on the AC electric motor housing, then the inverter and motor can be integrated, but the overall size increases due to shape mismatch and mounting space requirements

Engineering Contradiction:
Improveintegration of inverter and motorVSAvoidoverall size of power unit
Core Design Contradiction:
Device complexityVSVolume of moving object

Solution Approach 1:

The inverter is nested within the hollow interior cavity of the AC electric motor housing, allowing the inverter to be contained within the motor's existing structural space. This eliminates the need for separate mounting space and reduces the overall volume of the power unit while maintaining integration between the inverter and motor components.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Shape

If the inverter housing is made cylindrical to match the motor shape, then packaging efficiency improves, but the longitudinal occupancy increases significantly

Engineering Contradiction:
Improvecylindrical shape compatibilityVSAvoidlongitudinal occupancy
Core Design Contradiction:
ShapeVSLength of stationary object

Solution Approach 1:

Instead of extending the inverter longitudinally along the motor shaft, the inverter is positioned in the radial dimension by nesting it within the hollow interior cavity of the motor housing. This dimensional shift from longitudinal to radial placement reduces the longitudinal occupancy while maintaining cylindrical shape compatibility for compact packaging.

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

3Reliability

If conventional wiring and connectors are used to link the inverter and motor, then electrical connections are established, but the wiring complexity and number of components increase

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidwiring and connectors
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The inverter and AC electric motor are merged into a single integrated assembly with the inverter nested within the motor housing. This consolidation eliminates the need for extensive external wiring and multiple connectors, reducing wiring complexity and component count while maintaining reliable electrical connections through integrated busbars and direct mounting.

Inventive Principle:
Principle #5Merging (Combining)

4Device complexity

If the inverter is mounted on the motor housing, then integration is achieved, but cooling effectiveness of the combined unit is insufficient

Engineering Contradiction:
Improveintegration of electronic unitsVSAvoidcooling effectiveness
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The motor housing is designed with differentiated local properties: it serves as both a structural enclosure and a thermal management component. The housing includes dedicated cooling channels and thermal pathways specifically oriented toward the inverter's location within the cavity, providing localized cooling effectiveness to the integrated electronic units without compromising the overall integration benefits.

Inventive Principle:
Principle #3Local quality

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 configuration results in a more compact design with improved cooling efficiency and reduced wiring complexity, enhancing operational reliability and efficiency by allowing precise monitoring and control of the AC electric motor.

Implementation Method 1

a cooling jacket surrounding the stator

Methodology Applied
Scientific EffectHeat transfer: Convection

Implementation Method 2

a power assembly configured to receive direct current (DC) power from a DC power source and to convert the DC power into AC power

Methodology Applied
Scientific EffectPower conversion:

Data Source

PatentEP4593261A1Electric power unit
Publication Date: 2025.07.30 BRP-ROTAX GMBH & CO KG
  • EP4593261A1 patent drawingFigure 1
  • EP4593261A1 patent drawingFigure 2
  • EP4593261A1 patent drawingFigure 3

AI summary

An electric power unit comprises an AC electric motor, a power assembly, and a control assembly. The AC electric motor has a housing and an output shaft supported in the housing, the housing having a first end and a second end opposite the first end, the output shaft protruding from the first end. A combination of the power assembly and of the control assembly forms a DC to AC inverter. The power assembly receives DC power from a DC power source and converts the DC power into AC power. The control assembly controls a transmission of the AC power from the power assembly to the AC electric motor. The power assembly is disposed on a longitudinal side of the housing, the longitudinal side extending between the first and second ends of the housing. The control assembly is mounted on the second end of the housing.