Electronic Isolating Relay Module for Motor Arrangement

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Solution Overview

Problem

Existing servo drives in electronic steering systems face reliability issues due to mechanical relays' low reliability and heat management challenges in electronic star-point relays, which can lead to unsteerable vehicles in case of short circuits.

Innovation Solution

A compact motor system with an integrated electronic isolating relay module inside the motor housing, utilizing a contact guide element and a ceramic printed circuit board for heat dissipation and protection, allowing for efficient de-energization of motor phases during faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If mechanical relays are used for isolating motor phases, then the device structure is simple, but the reliability is reduced due to mechanical fatigue and blocked components

Engineering Contradiction:
Improverelay structureVSAvoidphase separation reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces mechanical relays with an electronic switching device (MOSFETs or IGBTs) controlled by a control unit. The electronic switches are driven by gate signals that open or close the motor phase connections without mechanical moving parts, eliminating mechanical fatigue and blocking issues while maintaining the phase isolation function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If electronic relays are used to improve reliability, then the reliability increases, but heat dissipation becomes a challenge requiring suitable design

Engineering Contradiction:
Improvephase separation reliabilityVSAvoidheat dissipation
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent introduces a heat dissipation plate as an intermediary thermal management component. The power semiconductor switches (MOSFETs/IGBTs) are mounted on this plate, which conducts heat away from the active components. The plate is thermally coupled to the motor housing or dedicated cooling structures, providing a thermal pathway that manages heat without affecting the electronic switching reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If the isolating relay module is integrated inside the motor housing, then the space is saved and protection is improved, but the heat management becomes more challenging

Engineering Contradiction:
Improvemotor system volumeVSAvoidheat dissipation
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The patent merges the isolating relay module with the motor housing structure. The housing serves multiple functions: mechanical protection of the electronic components, structural support for the switching device, and thermal conduction path for heat dissipation. The power switches are mounted on housing elements that are thermally coupled to the main housing body, which acts as a heat sink.

Inventive Principle:
Principle #5Merging (Combining)

4Volume of moving object

If the electronic isolating relay module is arranged on the housing element inside the housing, then the space is saved, but the connection resistance must be minimized

Engineering Contradiction:
Improvemotor system volumeVSAvoidconnection reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent implements preliminary action by providing through-conductors embedded in the housing element before the power semiconductor switches are mounted. These through-conductors establish low-resistance electrical pathways from the switching device to the motor phase windings. The housing element is designed with integrated conductive traces and contact elements that ensure optimal electrical connection is achieved as part of the assembly process, eliminating the need for additional high-current connectors.

Inventive Principle:
Principle #10Preliminary action

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

Enhances reliability and failsafety by ensuring low resistance connections and effective heat management, preventing generator operation during short circuits and maintaining vehicle steerability.

Implementation Method 1

A contact guide element which is provided non-conductively with a through conductor and which extends into a through opening of the housing element in order to create contact between an inside and outside of the housing element

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the isolating relay module can be arranged on a printed circuit board, in particular a ceramic printed circuit board, which is arranged on an elevation that is formed on a surface of the housing element

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2147498B1Motor arrangement with an electronic isolating relay module
Publication Date: 2016.02.24 ROBERT BOSCH GMBH
  • EP2147498B1 patent drawingFigure 1~2
  • EP2147498B1 patent drawingFigure 3~4
  • EP2147498B1 patent drawingFigure 5~6

AI summary

The invention relates to a motor arrangement, in particular for use in an electronic steering system, comprising a polyphase motor (1) in a motor housing (10); a housing element (14), which forms a part of the motor housing (10); an electronic isolating relay module (2, 40) in order to switch one or more motor phases such that their current does not flow in the event of a fault; wherein the isolating relay module (2, 40) is arranged in the housing interior on one side of the housing element (14).