Revision as of 18:01, 25 February 2014

Smart shade literature Review

here is the methods for smart shade project, go back to smart shade literature Review.

Methods

introducing the project:

During night, when window shades are left open, a lot of heat from the inside is lost. This project aims to implement photovoltaic cells in the shades such that they cause the shades to open and generate electricity during the day, and automatically close the shades at night. The key feature is the dual implementation of PV cells as power sources and as light sensors. Due to this, the heat lost during the night through windows can be conserved, which in-turn reduces the heating energy costs for buildings and improves their energy efficiency.[1-2]

General review of method

The logic is to compare the desired temperature to room temperature and opens or closes the blinds based on temperature difference. Rather than sensing temperature, this could also be done in another way, by sensing the amount of voltage produced by the PV cell, thereby gauging the amount of ambient light and controlling the shades based on that.

required components	detail
DC Motor	GM3
SPDT Relay	For switching motor
SPST switch	For discharging Power storage
PV panel	Power source or sensor
Ultracapacitor or battery	Power storage
Controller	Arduino Uno
Power resistor	For discharging ultracapacitor
DC-DC Converter
Fuse holder and Fuse

Hardware Components

PV Panel

A small C-Si PV panel is used to act as a light-controlled switch for the window shade, and also charge the battery. It was tested under bright light conditions and found to generate a no-load voltage upto 6V DC.

DC-DC Converter

The Arduino Uno micro-controller requires 5V DC for power, so a DC-DC buck-boost converter is used to maintain a constant 5V voltage across the battery terminals. As the converter has to deal with low input voltages, The LT1073-5 was selected due to the few number of external components needed, as well as its low required input voltage (1V).

Electric Motor

Due to its cheap cost, a small geared hobby motor was selected, utilizing a potentiometer for position feedback. The GM3 geared hobby motor provides up to .34 Nm of torque at rated voltage.

Battery

For energy storage, a Li-ion battery will be used to provide 5V output to the micro-controller circuit and the motor. It's specifications are yet to be determined.

Future Works

This project's design aims to be safer due to the lack of an ultra-capacitor, more compact and cheaper. If more time was available, it is possible to have developed future iterations of this project to extend its functionality beyond just window shade control, such as utilizing the window shade position to change the indoor electrical lighting intensity. More complex models may be used to operate the blinds at many different angles to allow varying amounts of sunlight depending on the time of the day, rather than just open/close positions. An additional PV cell could be placed indoors too, close to a light source, so that it can generate electricity to charge the battery using the indoor electrical lighting at night. Based on the data that is to be found on potential energy savings for a building outfitted with these smart shades, we can extrapolate that to find the savings for a small town or city block if all buildings utilize them.

reference

1. Tzempelikos, Athanassios; Andreas K. Athienitis (2007). "The impact of shading design and control on building cooling and lighting demand". Solar Energy 81 (3): 369 – 382. doi:10.1016/j.solener.2006.06.015. ISSN 0038-092X
2. M., Zaheer-Uddin (1987). "The influence of automated window shutters on the design and performance of a passive solar house". Building and Environment 22 (1): 67-75. doi:10.1016/0360-1323(87)90043-6. ISSN 0360-1323

@@ Line 51: / Line 51: @@
 |-
 |}
-==components detais==
+==Hardware Components==
 =====PV Panel=====
-The PV panel is still yet to be determined, however, it would be best if its open circuit voltage is close to 2.7 volts.  This would prevent the ultracapacitor from overcharging no matter what.<br />
+A small C-Si PV panel is used to act as a light-controlled switch for the window shade, and also charge the battery. It was tested under bright light conditions and found to generate a no-load voltage upto 6V DC.<br />
 =====DC-DC Converter=====
-Given that the Arduino Uno used as the controller in this experiment is powered off of a 5V power source, a method is needed to convert the ultracapacitor voltage.  Using Digikey's search feature, a number of DC-DC converters were found to output 5v.  The LT1073-5 was selected due to the few number of external components needed, as well as its low required input voltage (1V).<br />
+The Arduino Uno micro-controller requires 5V DC for power, so a DC-DC buck-boost converter is used to maintain a constant 5V voltage across the battery terminals. As the converter has to deal with low input voltages, The LT1073-5 was selected due to the few number of external components needed, as well as its low required input voltage (1V).<br />
 =====Electric Motor=====
-Servo, stepper, and DC motors were considered for the window blind actuation.  The cheapest option was found to be a geared hobby motor utilizing a potentiometer for position feedback.  The GM3 geared hobby motor provides up to .34 Nm of torque at ultracapacitor voltage.<br />
+Due to its cheap cost, a small geared hobby motor was selected, utilizing a potentiometer for position feedback. The GM3 geared hobby motor provides up to .34 Nm of torque at rated voltage. <br />
-=====Ultracapacitor=====
+=====Battery=====
-The power storage component was fortunately given from a cost standpoint, but unfortunate from an engineering standpoint.  It is governed by the relationship of current to the change in voltage in a capacitor.
+For energy storage, a Li-ion battery will be used to provide 5V output to the micro-controller circuit and the motor. It's specifications are yet to be determined. <br />
-:<math>i(t)= C\frac{\mathrm{d}v(t)}{\mathrm{d}t}</math>.
-Given that the voltage range of the ultracapacitor to be 1.0-2.7V dictated by the maximum ratings of the ultracapacitor and minimum ratings of the DC-DC converter, this means the voltage may drop 1.7V.  This equates to approximately 6.9 KJ of energy, enough to run the selected motor at its maximum power at 3V for over an hour - much longer than is needed.<br />
-====Ultracapacitor Safety====
-Due to the high energy content and discharge rate of the ultracapacitor, considerations must be taken into account to keep the ultracapacitor from being over charged.  A relay is put in between the PV panel and ultracapacitor.  It is normally closed, so it's default action is to charge the ultracapacitor.  However, the Arduino controller has control of the relay and reads in the ultracapacitor voltage as an analog input.  If this voltage is deemed to high, the Arduino has control to cut power to the ultracapacitor.
-Since there is a potential hazard to use such a large capacitor such as the 3000F Maxwell capacitor used in this experiment, a method is needed to easily and safely discharge the capacitor.  A power resistor is put in parallel with the ultra capacitor with a switch in series for this reason.  In practice, it may be useful to have this feature for time when users are away from the room for extended periods of time such as vacations.
 ==Future Works==

Smart shade method: Difference between revisions