P16262: EV Team Motor Test Stand
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Subsystem Design

Table of Contents

Team Vision for Subsystem-Level Design Phase

During the Subsystem Level Design Phase, we planned to execute some full system level feasibility analysis using representative components. This allowed us to fully verify that the subsystem concepts we chose ahead of time in the previous project phase would interface correctly and without major error.

Design Review Materials

Load Generation Subsystem

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

Load Generation Block Diagram

Current Status
Load Generation Requirements Flowdown

Load Generation Requirements Flowdown

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 original trial can be found below.

Motor/Generator Proof of Concept

This concept development was taken a step further, incorporating the switching device into the circuit as well, allowing us to use a low voltage to rapidly open and close the connection of the generator and the load resistor.

Motor/Generator Proof of Concept with IGBT

Future Goals
The next major step for this subsystem will be to choose a final product to be used as a load resistor. This component will need to safely dissipate nearly 15kW of power. There are a few different concepts currently under consideration.

These concepts are being considered based on their safety, reliability, and accuracy within the circuit.

Major Risks
Safety and thermal dissipation are the main two considerations for risk in this subsystem.

Central Test Controller Subsystem

This subsystem is intended to generate load and throttle commands, as well as processing the sensor signals.
Current Status
Central Controller Requirements Flowdown

Central Controller Requirements Flowdown

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.

The hardware is currently on its way to the Design Center!

Future Goals
Upon arrival, a quick setup will get us access to the hardware and software in the Senior Design Lab. We can then begin integrating the dSPACE hardware into our feasibility analysis tests.

dS1103 Board Information

Major Risks
No major risks have been identified.

Sensing Subsystem

This subsystem is intended to perceive test data from other subsystems and collate it.
Current Status
Sensing Block Diagram

Sensing Block Diagram

There are three main domains of sensory input that will be used to extrapolate much of the test output from the test bench.

First is voltage sensing. This will be done by voltage dividing down the driving input on the DC load motor and feeding this back into a dSpace IO pin.

Second is current sensing. This will be done using a high power current sensor that outputs a DC voltage to the dSpace IO pin proportional to the current in the system.

The third is angular velocity sensing. This will be done using an optical sensor and some reflective tape to figure out the shaft RPM by filtering the optical sensor output through an analog input pin on the dSpace board.

Sensing Requirements Flowdown

Sensing Requirements Flowdown

Future Goals
Once the sensors are ordered, feasibility tests need to be conducted using the small mechatronics lab motors, before scaling up to the full bench.
Major Risks
No major risks have been identified.

Bench Subsystem

This Subsystem is responsible for containing all the other subsystems in an ergonomic and space efficient manner without compromising safety or structural integrity.
Current Status
Concept Drawing of the Vertical Test Bench

Concept Drawing of the Vertical Test Bench

Bench Requirements Flowdown

Bench Requirements Flowdown

The concept of the bench has changed drastically since the last review. The EVT Lab has limited space, but underutilized vertical space. We decided to create a "bookshelf" with a shelf dedicated to a subsystem or subsystems. This design also makes shielding the moving parts easier and reduces the amount of material we would need. This design also features a bay where the unit under test can be easily mounted and swapped.
Future Goals
Once the final components for the other sub assemblies are finalized, the shelf dimensions can be finalized and the total space constraints and structural concerns can be calculated and tested.
Major Risks
No major risks have been identified

Coupling Subsystem

This subsystem is intended to allow quick swapping of test specimens with the load generator.
Current Status
Preliminary mechanical analysis regarding the required shaft sizes have been completed. Research has shown that while a "chuck" will allow for easier swapping, the method for installation of a chuck will be a Jacobs Taper, which is incredibly similar to the slot drive design. Using a Jacobs Taper would allow us to save money by not purchasing a chuck (especially with the required diameter) but would require us to provide enough pressure to engage the taper and prevent lash.
Taper Design

Taper Design

Diameter Analysis for Steel

Diameter Analysis for Steel

Future Goals
Major Risks

Project Planning

Week 6 Project Schedule

Week 6 Project Schedule


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