Drive Device Phase Order Inversion for Wiring Length Variation

Solution Overview

Problem

Existing drive devices for electric power steering systems face challenges in minimizing the variation of wiring length among phases, leading to inconsistencies in impedance and potential inefficiencies in power transmission.

Innovation Solution

The proposed drive device incorporates a rotating electric machine with a stator having two winding groups and a substrate-mounted inverter configuration, where the first and second extension lines are arranged with reversed phase orders, reducing wiring length variation and impedance differences among phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the inverter circuit is housed in one case attached on the outer shell of the compressor, then the device structure is simplified, but the wiring length variation among phases increases

Engineering Contradiction:

Improvedevice structureVSAvoidwiring length variation

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by arranging the first and second drive elements in symmetric regions relative to the shaft, but with reversed phase orders. This creates an asymmetric phase arrangement that compensates for wiring length differences, reducing impedance variation among phases while maintaining the simplified integrated structure.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent uses inversion by reversing the phase order of the second drive element relative to the first drive element. Specifically, if the first drive element has phase order U-V-W, the second drive element has phase order W-V-U. This inverted arrangement balances the wiring lengths from the stator windings to the inverter circuit, reducing impedance variation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Device complexity

If the phase arrangement order is not optimized, then the device structure remains simple, but the impedance variation among phases increases

Engineering Contradiction:

Improvephase arrangementVSAvoidimpedance consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies asymmetry by arranging the first and second drive elements in symmetric regions relative to the shaft, but with reversed phase orders. This creates an asymmetric phase arrangement that compensates for wiring length differences, reducing impedance variation among phases while maintaining the simplified integrated structure.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent uses inversion by reversing the phase order of the second drive element relative to the first drive element. Specifically, if the first drive element has phase order U-V-W, the second drive element has phase order W-V-U. This inverted arrangement balances the wiring lengths from the stator windings to the inverter circuit, reducing impedance variation.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9479025B2Drive device and electric power steering device including the drive device

Publication Date: 2016.10.25 DENSO CORP

AI summary

A drive device includes a rotating electric machine, a substrate, a first drive element, a second drive element, a first extension line, and a second extension line. The rotating electric machine including a stator with a first winding group and a second winding group wound on the stator in at least three phases. The first extension line and the first drive element, as well as the second extension line and the second drive element have respectively reversed phase orders in an arrangement of the phase orders from an end close to a reference position toward an other end of the arrangement. In such manner, variation of wiring lengths from an electric power supply region among different phases is reduced.