Transcript Solid State Relay Opto 22 - Purdue College of Engineering

ECE 477 Design Review – Spring 2010
Team 15
Team Members
Outline











Project Motive
Project Overview
Project-Specific Success Criteria
Block Diagrams
Component Selection Rationale
Packaging
Schematic
PCB Layout
Preliminary Software Design
Software Status
Project Timeline
Project Motive
Green Energy Management System aims to conserve
electric power by facilitating remote management of
household appliances through a web interface and a
touch screen.
Project Overview
 Adapter
 Connects to two appliances
 Monitor usage of power over time
 Communicates with a base-unit using R/F
 Can turn devices on/off on receiving appropriate
command
Project Overview
 Base
 Touch-Screen Interface
 Communicates with adapter using R/F
 Stores appliance usage data
 Usage based alerts , modes and statistics
 Hosts server and web-services for remote access
Project-Specific Success Criteria
 An ability to measure power consumption of plugged-in




devices over time
An ability to communicate with a base unit using RF and to
upload recorded information on a web server using the
Ethernet interface
An ability to turn devices on/off remotely
An ability to set up intelligent power plans to turn off
devices either after a fixed amount of time or after fixed
power consumption
An ability to use touch screen interface to control operating
parameters of the power management system
Block Diagram
ATD
MC9S12A512
(uC)
Rx
Tx
Transformer
ATD
(steps down voltage for
voltage sensing)
Solid State
Relay
Solid State
Relay
ATD
Transceive
r
TRM315LT
AC
in
AC out
Current
Sensor
AC out
Current
Sensor
RF
AC
in
Adapter Unit
Block Diagram
RF
Transceive
r
TRM315LT
Tx
MC9S12A512
(uC)
RS232
VGA
Intel Atom Board
Base Unit
USB
L
C
D
Touch screen
Rx
Component Selection Rationale
 Current Sensor
- Must be able to tolerate huge amounts of current (up
to 25A).
- Must be able to measure alternating current
- Muse be cheap and easy to use.
Solid State Relay
Opto 22 – 120D25
Carlo Gavazzi – RA 2410LA
Optical Isolation
Yes
No
Zero Switching
Yes
Yes
Control Voltage
3-32
3-32
Price
$26.50
$36
Component Selection Rationale
 Solid State Relay
- Optical Isolation for protecting the rest of the circuit
from current surges.
- Zero crossing for switching inductive loads.
- Control voltage should be low enough to be
produced by microcontroller.
Current Sensor
Tamura - L18P***D15
Allegro - ACS710
Output Voltage
4V
2.5V
Accuracy
+-1%
+-2.2%
Price
$12.50
$22.00
Component Selection Rationale
 Microcontroller
- Low power consumption
- Multiple ATD channels.
- SCI interface or built-in RF interface
- Cost effective (Must be cheap as it would have to be
installed in every power adapter.)
Component Selection Rationale
Microcontroller
ATMEGA128RFA1
Freescale mc9S12A512
# of pins
64
112
# of I/O pins
38
54
Program Memory (kB)
128k(Flash) 4k(EEPROM)
14k (RAM), 4K(EEPROM)
Flash (kB)
16k
512K
ATD resolution
8 bit
10 bit
Power Consumption
16mW
25 mW
Documentation
Yes
Yes
Price
Sample Available
Sample Available
Availability
Shipping Delayed
Available
Packaging
Solid State Relay
PCB
Plug point
Fuse box and
switch
2.5 x 3.5
cm
3.3cm
4 cm
Adapter Unit
7.5 cm
7 cm
6 cm
18 cm
Packaging
Base Unit
Schematic & Theory of
Operation
 Main Components
 Power Supply Circuit

Voltage Regulator circuits
 Microcontroller Circuit


Current Sensor Circuits
Voltage Sensor Circuits
Power Supply
 120 V AC voltage stepped down to 25V using simple
center – tapped step down transformer
 3 sets of rectifier circuits connected to specific voltage
regulators to generate a regulated DC supply
 +/- 15 V (7915,7815)
 +/-5V (7905,7805)
 +/-2.5V (2937,2837)
Schematic
 Power Supply
Schematic
 Voltage Regulator Circuit
Voltage Sensors
 Stepped down voltage to 5Vpp
 V out shifted up by 2.5 V to get accurate value on ATD
of microcontroller
 Voltage shift is done using adder circuits using 741
operational amplifiers
Schematic
 Voltage Sensor
Current Sensors
 Current Sensors work on hall effect principle
 Small in size
 PCB mountable
 Keeps direct line current away from PCB
 The output voltage varies between +/- 4 Vpp based on
amount of current
 The output voltage is shifted up by 2.5 V to get accurate
reading on the ATD.
Schematic
 Current Sensor
Solid State Relays
 The solid state relays work on DC control which varies
between 3V – 32V
 Allows current to flow above 3.5 V
 Provides optical isolation to rest of the circuit when
switched off
Microcontroller
 Sample the voltages from current sensor and voltage
sensor circuits
 Transmit the collected data to the base station
 Receive control signals from the base station and
control the appliances accordingly
Schematic
Microcontroller Circuit
PCB Design Considerations
 2 PCB boards
 Power Adapter: Small, narrow to allow for portability.
 Base Unit: Must be able to fit a small LCD display (10”)
 Microchip Transceiver close to PCB edge.
 Current Sensor must be close to PCB edge.
 High Electromagnetic Interference from the power
lines and most electric lines.
Microcontroller Layout
 Decoupling capacitors must be placed as close to the
IC as possible.
 Voltage regulators must be used to ensure that
maximum input voltage of ATD is not exceeded.
 The supply voltage to the microcontroller must be
satisfied from the power line voltage. This requires the
use of current rectifiers and regulators to supply DC
voltage.
 Tri-state buffers are required for the Tx/Rx pins
Microcontroller Layout
• Bypass filters placed
close to micro controller
•Pierce oscillator circuit for
generating clock
•Regulated 2.5 V power
supply
Power Supply
 The following voltage supplies are needed for different
circuit components - +15,-15,+5,-5,+2.5V
 The power supply needed by most of the components
is DC thereby requiring the use of rectifiers and
voltage regulators.
 Requires circuit components which can tolerate high
amounts of current(0-20A) and voltage fluctuations.
Power Supply
• 3 sets of regulated
voltage supply ( +/15V,+/-5V, 2.5V)
•Rectifier circuits placed
at the edges
PCB Layout
PCB Layout
RF
transceiver
& tristate
buffer
Voltage
Regulator +/-15V
Voltage
Regulator +/5V
MC9S12A512
Voltage
Regulator +/2.5V
Current Sensors
BDM
Preliminary Software Design
 Power Adapter Unit
 Decided on TCP/IP like protocol to communicate with
base station.
 Used Real-time interrupts of the microcontroller to
initiate the ATD conversion.
 Multi-Channel ATD conversion carried across three
channels. (2 for current sensor and 1 for voltage sensor)
 Send the recorded values using Serial Communication
Interface to the RF transceiver.
 Check for incoming commands from the base station at
regular intervals
Preliminary Software Design
 Base Station
 Receive data sets from the RF transceiver using the serial
port
 Buffer any on/off signals for devices and transmit them
at regular intervals
 Send the data sets to the Intel Atom Board using the
COM port
 Host a web-server on the Intel Atom board so that it
could be accessed using a web-browser
Software Status
 Adapter Unit
 Majority of software complete except for interface with
R/F module and network protocol
 Base Unit
 XP has been installed
 Apache Servers installed
 Touch Screen interfaced (Drivers, etc.)
Project Timeline
Design Review
Finalizing PCB design
ATD module
Setting up RF interface using SCI
Debugging data transmission
errors
Configuring firmware and webserver on Intel Atom Board
Setting up RF interface on base
station
GUI development for base
station
Writing Web Services
Packaging
Debugging
Week
8
Week
9
Week
10
Week
11
Week
12
Week
13
Week
14
Week
15
Week
16
1-Mar
8-Mar
15-Mar
22-Mar
5-Apr
12-Apr
19-Apr
26-Apr
3-May
Questions