Stepped Bus Bar Design for Motor Drive Apparatus

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing motor drive apparatuses face challenges in achieving low heat loss, high coupling strength, high vibration resistance, and low production cost due to difficulties in processing narrow-width bus bars and the limitations of traditional screw-fastening methods, which result in increased production costs and heat loss.

Innovation Solution

A motor drive apparatus design featuring a bus bar with a stepped structure and a conductive support block, where the bus bar includes a first plate-like connector portion fixed to the power device, a second connector portion connected to the printed wiring board, and an extension portion passing through a hole in the board, allowing for improved mechanical strength and reduced heat loss through a larger contact area and elastic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional screw-fastening methods are used to connect the bus bar to the power device, then coupling strength can be achieved, but heat loss increases due to small contact area and processing difficulties

Engineering Contradiction:

Improvecoupling strengthVSAvoidheat loss

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The bus bar is divided into multiple sections with different structures: a first connector portion for the power device, a second connector portion for the printed wiring board, and an extension portion connecting them. This segmentation allows each part to be optimized for its specific function, resolving the contradiction between coupling strength and heat loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the bus bar are given different local qualities: the first connector portion has a plate-like structure with large contact area for low heat loss, while the extension portion has elastic properties for vibration resistance. This local differentiation resolves the contradiction between coupling strength and heat loss.

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If the bus bar is processed by sheet-metal process to achieve narrow width, then device compactness is improved, but manufacturing difficulty increases making production cost higher

Engineering Contradiction:

Improvedevice compactnessVSAvoidmanufacturing difficulty

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The bus bar incorporates an elastic extension portion that can dynamically adapt to assembly variations and mechanical stresses. This dynamic property allows the narrow-width bus bar to maintain connection reliability without requiring complex processing, resolving the contradiction between compactness and manufacturing ease.

Inventive Principle:

Principle #15Dynamics

3Length of moving object

If the bus bar is made with narrow width to reduce space, then device dimension is reduced, but vibration resistance decreases

Engineering Contradiction:

Improvedevice dimensionVSAvoidvibration resistance

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The bus bar transitions from a two-dimensional narrow strip to a three-dimensional structure with an extension portion that passes through the printed wiring board. This dimensional change provides mechanical anchoring that enhances vibration resistance while maintaining compact overall dimensions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The extension portion of the bus bar is designed with elastic properties, acting as a flexible element that can absorb vibration and mechanical stress. This flexibility compensates for the narrow width, maintaining vibration resistance while keeping the device compact.

Inventive Principle:

Principle #30Flexible shells and thin films

4Ease of manufacture

If production cost is reduced by simplifying processing, then manufacturing cost decreases, but assembly complexity increases

Engineering Contradiction:

Improveproduction costVSAvoidassembly complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The bus bar integrates multiple functions into a single component: electrical connection, mechanical support, vibration damping, and structural alignment. By merging these functions into one piece rather than using separate components, the invention reduces production cost while keeping assembly simple.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11451104B2Motor drive apparatus having electric power flowing into/out of power device through bus bar

Publication Date: 2022.09.20 FANUC LTD

AI summary

A motor drive apparatus includes: a power device constituting a portion of a power conversion circuit for generating electric power for driving a motor and having input/output terminals; a printed wiring board having a hole; a bus bar connected to both of the power device and the printed wiring board, wherein the bus bar includes a first plate-like connector portion to be fixed to the input/output terminal, a second connector portion to be connected to the printed wiring board, and an extension portion extending between the first connector portion and the second connector portion that will pass through the hole.