HOW POWERWALL WORKS

Inside a Cell Phone

On a "complexity per cubic inch" scale, cell phones are some of the most intricate devices people use on a daily basis. Modern cell phones can process millions of calculations per second in order to compress and decompress the voice stream. If you have readHow Cell Phones Work, you know that they can transmit and receive on hundreds of FM channels, switching channels in sync with base stations as the phone moves between cells.

If you ever take a cell phone apart you will find that it contains just a few individual parts:

• A microscopic microphone
• A speaker
• An LCD or plasma display
• A keyboard not unlike the one we saw in a TV remote control
• An antenna
• A battery
• An amazing circuit board containing the guts of the phone

The circuit board is the heart of the system. Here is one from a typical Ericsson cell phone:

In this picture several of the components are identified. Starting from the left you the see the Analog-to-Digital and Digital-to-Analog conversion chips. You can learn more about A-to-D and D-to-A conversion and its importance to digital audio in How CDs Work. The DSP is a "Digital Signal Processor" -- a highly customized processor designed to perform signal manipulation calculations at high speed. This DSP is rated at about 40 MIPS (Millions of Instructions per Second) and handles all the signal compression and decompression. The microprocessor (Ericsson phones use an ASIC version of the Z-80) and memory handle all of the housekeeping chores for the keyboard and display, deal with command and control signaling with the base station and also coordinate the rest of the functions on the board. The RF and power section handles power management and recharging and also deals with the hundreds of FM channels. Finally the RF (Radio Frequency) amplifiers handle signals in and out of the antenna.

What is amazing is that all of that functionality -- which only 30 years ago would have filled the entire floor of an office building -- now fits into a package that sits comfortably in the palm of your hand.

DC Motor Speed and direction control over GSM Mobile/Modem

This is a DC Motor Control Device which controls the stepper motor through messages received as SMS or GPRS Packets and also sends acknowledgment of task. These devices are designed to remotely control the DC Motor from anywhere and anytime. This remote control DC motor control device is possible through embedded systems. The toolkit receives the SMS, validates the sending Mobile Identification Number (MIN) and performs the desired operation after necessary code conversion. The system is made efficient by SIMs so that the SMS can be received by number of devices boards in a locality using techniques of time division multiple access. With this in mind, we have designed the project to work with sim300 technology.

The speed of the motor is measured using contact-less speed measurement technique. Speed control is done using PWM (Pulse Width Modulation) method. User can send SMS messages to control the motor speed and direction. A GSM modem attached to the control unit handles automatic SMS sending and receiving process. As this monitoring and controlling can be done by any mobile phone, we provided a security feature by implementing password-based protection. User has to send the password along with the commands to be controlled.

The purpose of this project is to control the speed and direction of DC Motor using Microcontroller and GSM Modem with password protection. This uses a PWM (Pulse Width Modulation) technique to control the speed of motor from 0% to 100%.

The SMS can be sent to any mobile user of any service provider with no or minimum charge. This system is designed using a GSM modem. The GSM modem is configured as a receiver. The SMS sent by the user is written in a particular format. The controller receives the message and decodes it and identifies the task to be done and the SMS received by the controller is decoded, and the proper message is displayed on the LCD by the microcontroller.

GSM Modem connected to microcontroller unit is used to control the motor and know the motor live speed. Microcontroller automatically reads the SMS messages stored in the SIM card and takes necessary action like speed control, direction control etc. There will be a particular code that needs to be sent through SMS to set the speed and get the speed from the DC motor.

Components

• GSM Module – SIM 300

                                                                       

This GSM Modem can accept any GSM network operator SIM card and act just like a mobile phone with its own unique phone number. Advantage of using this modem will be that you can use its RS232 port to communicate and develop embedded applications. Applications like SMS Control, data transfer, remote control and logging can be developed easily.The modem can either be connected to PC serial port directly or to any microcontroller. It can be used to send and receive SMS or make/receive voice calls. It can also be used in GPRS mode to connect to internet and do many applications for data logging and control. In GPRS mode you can also connect to any remote FTP server and upload files for data logging.

This GSM modem is a highly flexible plug and play quad band GSM modem for direct and easy integration to RS232 applications. Supports features like Voice, SMS, Data/Fax, GPRS and integrated TCP/IP stack.

• PIC 16F887

The PIC16F887 is one of the latest products from Microchip. It features all the components which modern microcontrollers normally have. For its low price, wide range of application, high quality and easy availability, it is an ideal solution in applications such as: the control of different processes in industry, machine control devices, measurement of different values etc. Some of the features are as follows:-

                                                             

·        RISC Architecture

·        Oscillator Support 0-20 MHz

·        In Circuit Serial Programming Option (ICSP)

·        Watch-Dog Timer

·        Brown-out Reset (BOR) with software control option

·        Power saving sleep mode

·        Enhanced UART Module

·        256 bytes EEPROM

·        PWM output steering control

• Motor Driver IC – L293D

The L293 and L293D are quadruple high-current half-H drivers. The L293 is designed to provide bidirectional drive currents of up to 1 A at voltages from 4.5 V to 36 V. The L293D is designed to provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V. Both devices are designed to drive inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well as other high-current/high-voltage loads in positive-supply applications. All inputs are TTL compatible. Each output is a complete totem-pole drive circuit, with a Darlington transistor sink and a pseudo-Darlington source. Drivers are enabled in pairs, with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 enabled by 3,4EN. 

                                                               

When an enable input is high, the associated drivers are enabled and their outputs are active and in phase with their inputs. When the enable input is low, those drivers are disabled and their outputs are off and in the high-impedance state. With the proper data inputs, each pair of drivers forms a full-H (or bridge) reversible drive suitable for solenoid or motor applications.

Block Diagram

                                                                   

Circuit Diagram

                                                                  

GSM technology capable solution has proved to be controlled remotely, provide industrial security has achieved the target to control different industrial appliances remotely using the SMS-based system satisfying user needs and requirements GSM technology capable solution has proved to be controlled remotely, provide industrial security and is cost effective as compared to the previously existing systems.

Different method for correction of power factor

Losses In Transformer

Losses In Transformer

 An electrical transformer is an static device, hence mechanical losses (like windage or friction losses) are absent in it. A transformer only consists of electrical losses (iron losses and copper losses). Transformer losses are similar to losses in a DC machine, except that transformers do not have mechanical losses.
Losses in transformer are explained below -

(I) Core Losses Or Iron Losses

Eddy current loss and hysteresis loss depend upon the magnetic properties of the material used for the construction of core. Hence these losses are also known ascore losses or iron losses.

§  Hysteresis loss in transformer: Hysteresis loss is due to reversal of magnetization in the transformer core. This loss depends upon the volume and grade of the iron, frequency of magnetic reversals and value of flux density. It can be given by, Steinmetz formula:
W_h= ηB_max^1.6fV (watts)       where,   η = Steinmetz hysteresis constant
                                                     V = volume of the core in m³

§  Eddy current loss in transformer: In transformer, AC current is supplied to the primary winding which sets up alternating magnetizing flux. When this flux links with secondary winding, it produces induced emf in it. But some part of this flux also gets linked with other conducting parts like steel core or iron body or the transformer, which will result in induced emf in those parts, causing small circulating current in them. This current is called as eddy current. Due to these eddy currents, some energy will be dissipated in the form of heat.

 (Ii) Copper Loss In Transformer

Copper loss is due to ohmic resistance of the transformer windings.  Copper loss for the primary winding is I₁²R₁ and for secondary winding is I₂²R₂. Where, I₁ and I₂ are current in primary and secondary winding respectively, R₁ and R₂ are the resistances of primary and secondary winding respectively. It is clear that Cu loss is proportional to square of the current, and current depends on the load. Hence copper loss in transformer varies with the load.

Efficiency of Transformer

Just like any other electrical machine, efficiency of a transformer can be defined as the output power divided by the input power. That is  efficiency = output / input .Transformers are the most highly efficient electrical devices. Most of the transformers have full load efficiency between 95% to 98.5% . As a transformer being highly efficient, output and input are having nearly same value, and hence it is impractical to measure the efficiency of transformer by using output / input. A better method to find efficiency of a transformer is using, 

efficiency = (input - losses) / input = 1 - (losses / input).

Condition For Maximum Efficiency

Let,Copper loss = I₁ ²R₁ & Iron loss = Wi 

Hence, efficiency of a transformer will be maximum when copper loss and iron losses are equal.
         That is Copper loss = Iron loss.

Clean Solar Power to Replace Fossil Fuel

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India has recently stepped it up in terms of the government’s support of renewable energy through its efforts in moving from coal powered railways to clean solar panels for electricity and fuel consumption.

The Indian Railways is one of the largest railway systems in the world,  requires massive energy expenditures – specifically 17.5 kWh of electricity per year, and over 90,000 liters of diesel.

Fuel bills are actually the 2nd largest expense of the Indian Railways. With rising prices of fuel imports, the Indian government has began focusing on other forms of energy to power the coaches, specifically solar energy.

Recently, the first solar powered coach was tested, which is a non-airconditioned coach with solar panels installed on its rooftop. The Rewari-Sitapur passenger train was able to generate 17 kWh for an entire day, which was enough to cover only the lighting load of the coach.

Two other coaches have been fitted with solar panels, but are yet to begin their testing stage. These said coaches belong to 2 narrow-gauge trains for the Pathankot-Jogindernagar route in the Kangra Valley and the Kalka-Shimla section.

This massive project and potential move to clean energy is touted to solve two major problems faced by the IR today: rising energy prices and the threats to environment caused by the massive use of fossil fuels. Ideally, the trains will still be powered by traditional diesel-run engines, but the lighting of the passenger coaches will utilize solar energy.

According to a Northern Railway official, there is a total of 40 square meter of space on a typical coach rooftop. The said coach was fitted with 12 solar panels over 24 square meters, but the remaining 16 square meters can still accommodate 6 more panels for more energy production.

Officials say that India has a huge potential for solar power, and that the installation of solar panels are not limited to the train’s rooftops, but can also include those of the railway’s buildings to provide renewable energy for its infrastructure.

The typical cost for fitting panels on one coach is Rs 3.90 lakh, and its return on investment per year is Rs 1.24 lakh. The potential savings of millions of dollars can also include that of foreign exchange reserves in terms of diesel imports. Aside from solar power’s obvious economic benefits for the IR, the use of clean solar power also reduces their emission of carbon dioxide by over 200 tonnes in a year.

Currently, the Indian government is planning to create a solar policy that would lead the way to the production of 1000 megawatts of solar power in the next 5 years. The main aim of the said policy states that by the year 2020, the IR’s renewable energy production will be able to provide at least 10% of the entire enterprise’s energy consumption need.

Today, the project is aimed at a few rooftops lighting up a few non-airconditioned coaches. Future testing is still needed to understand the economics of the proposal before it is implemented on a larger scale. So far, results have been promising and further positive data might just lead the Indian Railways to utilize the use of clean solar energy for all of its coaches.

Wireless energy transmission

Wireless energy generation in space is one step closer to becoming a feasible delivery source of power following a new experiment that transmitted electricity through microwaves.

The Japan Aerospace Exploration Agency (Jaxa) conducted the research, which sent 1.8 kilowatts of electricity 170 feet through the air, in the form of microwave radiation. The beam was transmitted with a great degree of accuracy, showing the technique may be used on a larger scale.

Solar energy might, one day, be collected by massive solar panels in space, and the energy generated from the systems could be sent to Earth in the form of microwaves. Such networks for generating electricity in space would have some advantages over ground-based systems. Solar collectors in space would not be subject to the cycles of day or night, or cloudy conditions.

"This was the first time anyone has managed to send a high output of nearly 2 kilowatts of electric power via microwaves to a small target, using a delicate directivity control device," a Jaxa spokesman said.

Engineers at Jaxa have spent years researching new technologies to deliver energy from space-based solar collectors down to our home planet. Solar cells commonly power satellites, space probes, and the International Space Station. However, delivering that power to Earth in an economical manner is still a challenge facing developers.

Current plans to develop an orbiting energy generation system involve sending satellites into geostationary orbits more than 22,000 miles above the Earth. The satellites would require large solar panels. Challenges facing engineers include launching these massive solar collectors that high above the Earth, and maintaining them once they are in space. Because of these issues, Jaxa engineers believe that a full network to generate electricity in space will not be available until sometime in the 2040's.

Japan is dependent on imports for near all of its energy needs, feeding a desire to develop their own systems. The nation had utilized nuclear reactors to generate electricity, but those plants shut down in the wake of the 2011 Fukushima disaster.

Mitsubishi Heavy Industries recently announced its researchers have successfully transmitted around 10 kilowatts of electricity to a receiver located more than 1,600 feet.

The idea of producing energy in space and sending it to Earth for use has been studied by American researchers for more than 50 years.

Additional uses for the transmitters could include charging electric cars, or sending electricity to remote regions in the wake of natural and man made disasters. Future development of the current system could produce a device capable of transmitting and receiving energy from ocean platforms, far from the nearest coast.