Wireless User Interface for Variable Frequency Drives

Team 168Alex Shuster (EE)Michael Kloter (EE)Christopher Perugini (EE)Kevin Wei (EngPhys - EE)

Sponsor: Lenze Advisor: Professor John Chandy

Outline• Lenze

• Existing Problems

• Deliverables

• Solution▫Wireless▫Hardware

▫Network Topology

▫Transmission

▫Adaptation

• Budget

• Project Summary

Lenze

Provide Motor Control Solutions• Automotive Construction• Robotics• Manufacturing and Packaging

Variable Frequency Drives• Speed and Control System for AC motor

Existing Problems and Deliverables

Current Problems• Hardwired Communication• Manually Set Parameters• Limited Accessibility

Objectives • Develop VFD Wireless Interface• Maximize Transmission Distance• Multi VFD Operation• Industrial Grade

Wireless SolutionCommunication Options:

• Wi-Fi• Bluetooth• ZigBee

Wireless Communication Choice: ZigBee• 10-100m / Node • Unlimited Range Extension• Low Cost• Industrial Operation

Hardware Solution

B&B Electronics USOPTL4• USB Serial Converter• Transforms Serial

Signal to RS-485

Sparkfun ATMega128RFA1• MCU and ZigBee

Transceiver Combo• Cost Effective• Compact Size

Hardware ConstraintsMCU/Transceiver:

• Communicates using TTL levels• VFD requires RS-485 levels

Reference Voltage Conflict: RS-485 vs TTL

Solution:• Breakout Board Switching• MCU Code Modification

RS-485 TTL

High Reference Level

+200mV Differential 3.3V

Low Reference Level

-200mV Differential 0V

Software Stack Solution

• Basic Data Services

• Routing

• Power Management

• Network Management

• Data Failure Correction

• Message Payload Formatting

• Advanced Security

• MCU Power Management

• Hardware Peripheral Interface

Lightweight Mesh

Transceiver Scheme SelectionOptions:• FIFO Byte by Byte

▫Buffer vectors inserted in payload frame as received• FIFO Message

▫Waits for full message before sent to payload frame

Framing Choice: FIFO Byte by Byte• Simplicity

Transmission Options

Predefined Buffer Size•Transmits when buffer filled

Variable Buffer Size•Transmits when timer triggered

Real Time Transmission•Transmit data as received

Real Time Transmission

Easiest Method:•Each data byte transmitted to the VFD

once received from the computer

Most Convenient Method:

•Easily adaptable to other applications

•Will not restrict the use for future products

Indirect Adaptation

Indirect Adaptation

Problems:

•Added Costs•RS232/RS485 Converter Bulky

Solutions:•Direct Adaptation•Modify Code to Half Duplex•Incorporate GPIO from MCU

Direct Adaptation

Tx/Rx Control:•Tell RS485/TTL Transceiver when to

Send/Receive ▫ Incorporate GPIO from MCU

Direct Adaptation

TX/RX Control

TX/RX Control

RS485 to TTL

MCU+

Transceiver

TTL toRS485

MCU+

Transceiver

Computer to USB to RS485

TX/RX

RX

TX

GPIO

TX/RX TX/RX

TX/RX

GPIO

BudgetLenze Grant: $1000

Product Quantity Unit Price Price

Design Estimates

In System Programmer

1 $35.36 $35.36

Single Chip MCU and ZigBee Transceiver

3 $9.75 $29.25

RS-485 to TTL Transceiver

3 $2.70 $8.10

ZigBee Development Kit

1 $119.00 $119.00

RS-232 to RS-485 Converter

3 $80.11 $240.33

RS-232 to TTL Transceiver

3 $18.54 $55.62

Misc. Supplies $100.00

Total: $587.66

Project Summary

ZigBee PCB Antenna:• Easy to tune• Reduces Costs

MCU Integration:• Eliminate External

Hardware• Wireless Upgrade Package

Future Implementation

• Communication Established

• Hardwired Connections Eliminated

• Cost Effective Implementation

Questions