Download 11/29/2016 - Cognito Forms

Project
Pico Hydro
Project Record:
Research: Generator, Electrical Components,
and Circuit Design
Version 1
11/29/2016
Jonathan Rogers
Joshua Pardoe
1 | Page
Version History
Version
Date
Description/Notes
1.0
11/29/2016
MVP 2 Fall 2016
2 | Page
Table of Contents
Abstract
4
Goal
4
Electrical Research
5
General Electrical Knowledge
5
Alternator Research
7
Battery Research
10
Electrical load/Power Output Research
12
Conclusion
14
References
15
3 | Page
Abstract
In order to increase understanding of the team members in the electrical aspects in EMI’s
WEDGE prototypes, research was conducted on common electrical systems as well as specific
electrical components and their relation to each other in this project’s design. Within this
research, topics included general electrical knowledge, alternators, battery research, electrical
loads, and power output of an electrical system. Specific research was conducted on the
alternator on the WEDGE 3.0 prototype as well as a tangible load to use to measure power
output from the alternator. The research on the electrical load led to the completion of a load
made up of a series of lights which will be used in future testing of the prototypes. In general,
this research was conducted so that the electrical power generated by the turbine can be utilized
in the most efficient way through the electrical systems of the turbine.
Goal
To gain knowledge on electrical terminology and systems through summarizing research in
writing at the start of the 2nd MVP work cycle so that it can be used efficiently and accurately in
the testing and building of pico hydro turbines.
4 | Page
Electrical Research
General Electrical Knowledge
Common electrical terms:
AMPERE - A unit of measure for the flow of current in a circuit. One ampere is the amount of
current flow provided when one volt of electrical pressure is applied against one ohm of
resistance. The ampere is used to measure electricity much as "gallons per minute" is used to
measure water flow.
CAPACITOR - A device which stores electrical energy. Commonly used for filtering out voltage
spikes.
CHARGE - To restore the active materials in a storage battery by the passage of direct current
through the battery cells in a direction opposite that of the discharging current.
CURRENT - Movement of electricity along a conductor. Current is measured in amperes.
DIODE - An electrical device that will allow current to pass through itself in one direction only.
ELECTROLYTE - Any substance which, in solution, is dissociated into ions and is thus made
capable of conducting an electrical current. The sulfuric acid - water solution in a storage battery
is an electrolyte.
GENERATOR - A device which converts mechanical energy into electrical energy.
5 | Page
INDUCTANCE - The property of an electric circuit by which an electromotive force (voltage) is
induced in it by a variation of current either in the circuit itself or in a neighboring circuit.
OHM - The standard unit for measuring resistance to flow of an electrical current.
RECTIFIER - A device (such as a vacuum tube, commutator, or diode) that converts alternating
current into direct current.
TRANSFORMER - A device made of two coil windings that transfers voltage from one coil to
the next through electromagnetic induction. Depending upon the number of windings per coil, a
transformer can be designed to step - up or step - down its output voltage from its input voltage.
Transformers can only function with alternating current (AC).
VOLTAGE - That force which is generated to cause current to flow in an electrical circuit. It is
also referred to as electromotive force or electrical potential. Voltage is measured in volts.
WATT - A unit of measure for indicating the electrical power applied in a circuit. It is obtained
by multiplying the current (in amperes) by the electrical pressure (in volts) which cause it to
flow. That is: watts = amperes x volts.
WATT-HOUR - A unit of electrical energy. It indicates the amount of work done in an hour by a
circuit at a steady rate of one watt. That is, watt-hours = ampere-hours x volts.
6 | Page
Alternator Research
Alternators (General)
Alternator rotor - This rotor is made up of an iron core that was a coil of wire wrapped around
the core. The electric current strength determines the size and strength of the magnetic field. The
electric current is DC, which is supplied to the wire coil itself by some brushes and slip rings. An
alternator pulley drives the rotor.
Stator - The stator is a set of coils that surrounds the rotor. These coils do not turn seeing as how
they are fixed to the shell of the alternator. When the rotor turns inside of the stator coils, there is
a change in magnetic flux. This change in magnetic flux causes an induced current inside the
stator coils. However, because the rotor is constantly rotating, an AC current is produced in the
stator.
Output diodes - If the alternator is used in a DC application, the AC voltage from the stator has
to be converted to DC before it can be effectively used. The “bridge rectifier” is where the
conversion takes place. The bridge rectifier consists of diodes. Diodes are special in the fact that
they allow current to flow in one direction, while they block the flow in the other direction. The
output of the alternator is not a pure DC, but rather a pulsating DC.
7 | Page
Voltage Regulator - The voltage regulator consists of two inputs and one output. The two inputs
are control voltage input and electric current supply. The single output is for the field current that
does to the rotor. The control voltage input is used to control the electric current input that can
pass to the rotor coils.
The following diagram shows a schematic of an alternator in a car application:
8 | Page
DC-540 Low Wind Permanent Magnet Research
The alternator used in WEDGE 3.0 is a DC-540 Low Wind Permanent Magnet
Alternator. It contains a 303 stainless steel shaft which helps fight corrosion and maximizes
power output. The model consists of a 3-phase external rectifier output pigtail. This allows for
cheaper connectors and wires. The rectifier output can be connected for DC output if the battery
terminal located on the alternator is used. It is important to note, though, that only one output can
be connected to the battery at a time. Also, the rectifier output connector does not allow the
alternator to be a “grid-tie.” [1]
The chart below captures output of the alternator on a test stand. Voltages were recorded
with an open circuit configuration, while the Amperages were recorded with a short circuit
configuration. [1]
9 | Page
Figure 2. Composite graph of Volts vs RPM and Amps vs RPM for a DC-540 Low Wind
Permanent Magnet Alternator.
Battery Research
Batteries (General)
All batteries use chemical energy for storage. However, there are multiple types of batteries.
Each has different characteristics related to charge, storage, and discharge.
Nickel Cadmium battery: This type of battery is rechargeable. It uses metallic cadmium and
nickel oxide hydroxide as electrodes. Each cell has a nominal cell potential of 1.2 volts. For
normal AA batteries, 1.8 amperes is the maximum discharge rate. Sealed cells do have pressure
vessel which stores oxygen and hydrogen gas produced will they can combine into water.
Nickel-metal hydride battery: This type of battery is rechargeable. The chemical reactions at the
electrodes are similar to the Nickel Cadmium battery except the negative electrode uses a
10 | Page
hydrogen-absorbing allow. The Nickel-metal hydride battery can even be two or three times the
capacity of an equivalent size Nickel Cadmium battery. The cells in the battery have an alkaline
electrolyte. A fully charge battery will supply an average of 1.25 volts per cell if it is
discharging.
Lead acid battery - This type of battery is the oldest type of rechargeable battery. The cells have
a large power-to-weight ratio. As a result, the battery is able to supply high surge currents. When
discharging, the positive and negative plates become lead(II) sulfate. The electrolyte does lose
sulfuric acid. When fully charged, the negative plate is lead and the positive plate is lead dioxide.
There is concentrated sulfuric acid as the electrolyte. These types of batteries are most
commonly used in cars.
Lithium ion batteries - This type of battery is a rechargeable battery. The main concept behind
these types of batteries is that lithium ions go from the negative to positive electrode when
discharging and back when charging. There are three main components in a lithium-ion battery:
positive electrode, negative electrode, and electrolyte. These batteries are most common in
household electronics.
Lithium Polymer batteries - This type of battery is a rechargeable battery. It is in pouch format.
These batteries work on the processes of intercalation and de-intercalation. An advantage of this
type of battery is it can easily be produced in almost any shape.
Car Batteries
11 | Page
In order to use a car battery as a power source it needs to be connected to a power
inverter in order to convert DC to AC. This is done by connecting the positive terminal of the
power inverter to the positive post of the battery, connecting the negative terminal of the power
inverter to the negative post of the battery, turning on the power inverter, and waiting 30 seconds
before using the current. When choosing an inverted, the max wattage should be the wattage the
objects using the power need.
When measuring between the post of a battery, the voltage represents main battery
voltage minus the ESR which is the internal series resistance. This internal resistance can be
influenced the age, size, temperature, chemical properties, and discharge current of the battery.
The capacity of a battery is measured is A-h or mA-h (amp-hours). Power should be in terms of
W-h, but because V stays the same it is usually label in A-h for battery capacities. Smartphones
required 1800mA-h. The charging rate of a battery is called C or C-rate and is the charge rate as
a percent of full capacity in one hour. In order to increase the life of a battery, the specified rate
should be used from the battery datasheet. When choosing a battery, it is important to consider,
system run time, form factor, weight, and charging time. The battery is done charging usually
when it hits its current termination level but some batteries but can be done with safety timers if
charging takes too long. The current going into the battery when charging will be lower than the
theoretical value when a system is running of the battery because the system takes some of the
current away from the battery.
12 | Page
Electrical load/Power Output Research
In terms of power, P= IV = V2/R = I2R with the R being the sum of the internal resistance
of a battery and load resistance of the series circuit. In in our light board, the load resistance
would be the sum of the lightbulbs added up together. When R= the load resistance and r = the
internal resistance the power dissipated by the internal resistance Pr = I2r = V2r/(r+R)2 and the
power to the load PR = I2R = V2R/(r+R)2. When R = r, the power transfer is the most efficient so
that not too much is turned into heat internally (r > R) and the current is not too low to use (r <
R).
Light-board Load.
The light-board which was started last MVP was completed with 8 lights connected in
series. The light bulbs used were 12V and 100W in order to test up to as high of a power output
as possible and up to the maximum power output in the goal for the final turbine design of
13 | Page
800W.
Figure 3: Electrical schematic of circuit for determining power output if all eight light bulbs are
used on the current light board
To determine the power output with the light board, the alternator leads will be placed at
the connections between lightbulbs so that the light bulbs light up starting will one and
increasing until the alternator cannot light up the bulbs. The cutoff light bulb intensity to be
considered lit was determined to be 30 lumens per square foot off recommendations from the
IESNA handbook.
14 | Page
Figure 4 and 5: Connecting a power source to the light-board starting with one light bulb and
then increasing the number of light bulbs.
Conclusion
Teams members researched common electrical terms, alternators, and electrical
components in order to gain a better understanding of the water turbines. Batteries were also
researched as well electrical loads and power outputs. Specially attention was given to WEDGE
3.0. Specifically its alternator and adequate load needed. The team now has the electrical
background necessary to manufacture and analyze the turbine. These skills will be used in
boosting turbine efficiency.
15 | Page
References
[1]http://www.windbluepower.com/Permanent_Magnet_Alternator_Wind_Blue_Low_Wind_p/d
c-540.htm
[2]https://www.swtc.edu/ag_power/electrical/terms.htm
[3]https://alternatorparts.com/understanding-alternators.html
16 | Page