P16262: EV Team Motor Test Stand
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Systems Design

Table of Contents

Team Vision for System-Level Design Phase

During this phase, we planned to verify our systems level design choices, and begin the design of our system at a sub-system level. We were able to complete the subsystem design, and make many high level decisions to support subsystem design.

Problem Definition

This project focuses on the development of a Electric Motor Test Bench for RIT's Electric Vehicle Team. This project is designed to test the capabilities of the motor of an electric vehicle when used in conjunction with a motor control unit. The test bench will apply a dynamically variable load to the motor and controller, and then measure how these components react to the given conditions.

Customer Requirements

Customer Requirements were developed from meetings with the EVTeam, as well as various "startup packages" from the EVT team. We have further refined some of these requirements as per meetings with the EVTeam.
Customer Requirements Document

Customer Requirements Document

Engineering Specifications

Engineering Specifications were developed based off of the results of the Functional Decomposition, as well as from the Customer Requirements. These specifications have been further refined as per meetings with the EVTeam

Engineering Requirements Document

Engineering Requirements Document

Benchmarking

Purpose

During our systems level design, we wanted to take a look at the way that similar problems had been solved in the past, and ensure that our initial systems design had been validated by previous endeavors.

Previous Patents and Products

Brusa Test Bench

KST Test Bench

Motor Test Bench Patent

Systems Level Analysis

The team took a top-level down approach to the defined problem using tools like functional decomposition and pugh analysis. From a systems perspective, the general design was mostly defined already in the PRP document and via our discussions with the customer. Thus, the systems design phase started broaching topics within the upper echelons of the subsystem level. As seen below, we've already been able to make some decisions about subsystem design and begin acquisition of materials.

Requirements Tracabilility Matrix

The Requirement Matrix was used to guarantee coverage and traceability of the Customer Requirements, as well as avoiding non-useful Engineering Specifications.
Requirements Matrix

Requirements Matrix

Functional Decomposition

Purpose

We completed the Functional Decomposition as a method to verify that our engineering requirements were represented by subsystems in the functional design of the system. We found this to be a very effective exercise, and upon revisiting our functional decomposition after defining our systems level design, we found that none of the decomposition needed to be changed, but we added Engineering Requirement labels to each section for reference.

Systems Level Functional Decomposition

Functional Decomposition

Functional Decomposition

Subsystems Concept Development

Load Generation Subsystem

This subsystem is intended to generate the physical dynamic load on the system.
Concepts
Load Generation Concepts

Load Generation Concepts

Final Choice
The Electric DC Load Generator will allow for simple torque control, with an added element of safety for the UUT, as the load will be limited by the load resistor. We proved out the concept using a quick lab procedure, performed originally in Dr. Lyshevski's Mechatronics course. The video of our trial can be found below.

Motor/Generator Proof of Concept

Central Test Controller Subsystem

This subsystem is intended to generate load and throttle commands, as well as processing the sensor signals.
Concepts
Final Choice
The ds1103 Board

The ds1103 Board

The dSPACE Hardware was chosen for its ease of use, prior knowledge, and cost effectiveness. We received loaner hardware from dSPACE, as well as access to their software package. dSPACE is one of the world leaders in design of mechatronic system development and test hardware.

dS1103 Board Information

Motor Coupling Subsystem

Concepts
This subsystem is designed to allow a connection between the test motor and the load generator, also allowing "easy" swapping.
Mounting Concepts

Mounting Concepts

Below is an example calculation we used to establish shaft diameter requirements:

Mounting Concepts

Mounting Concepts

Final Choice
The final choice for this subsystem will be made during the next design cycle.

Bench Structure Subsystem

This subsystem is intended to provide the framework of the whole system.
Concepts
Final Choice

Extruded Aluminum framing: Allows us to purchase exactly what we need, provides many interface options and is very robust

Risks

Systems Level Test Plan

Systems Level Test

Systems Level Test

Project Plan

The high level vision for the project is to develop a prototyping platform for electric vehicle motor components and controllers. The platform should be safe, usable, and provide valuable unit test data to EVT engineers.

A more detailed project schedule can be found below, which goes into specific tasks associated with this project.

Week 6 Project Schedule

Week 6 Project Schedule


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