DESIGN AND CONSTRUCTION OF A 3.5KVA D.C TO A.C INVERTER SYSTEM
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ABSTRACT
This project is titled the design and construction of a 3.5KVA DC to AC inverter system. A power inverter is a device that converts DC power (also known as direct current), to standard AC power (alternating current). Inverters are used to operate electrical equipment from the power produced by a car or boat battery or renewable energy sources, like solar panels or wind turbines. DC power is what batteries store, while AC power is what most electrical appliances need to run so an inverter is necessary to convert the power into a usable form.
It is designed to meet up with the power demand in the offices and in homes in the absence of power supply from the national supply authority, NEPA. In order words the device / item serves as a substitute for NEPA which almost monopolises the power supply to people.
It is designed in such a way that it will take up 12v DC from battery and inverts it to an output of 220v, 50H2 AC. It makes no noise during operation and no hazardous carbon monoxide is generated in the surrounding. And this inverter delivers a power of 3.5KVA to a load, and for this reason it emits high current and requires thick wiring.
ABLE OF CONTENTS
Title Page
Approval Page
Dedication
Acknowledgement
Abstract
Table of Content
CHAPTER ONE
1.0 Introduction
1.1 Objective of the project
1.2 Significance of the project
1.3 limitation of the project
1.4 scope of the project
1.5 types of inverter
1.6 application of the project
CHAPTER TWO
2.0 Literature review
2.1 review of history of an inverter
2.2 review of how to choosing the right inverter
2.3 review of the difference between sine wave and modified sine wave inverter.
2.4 review of inverter capacity
2.5 safety of inverter
CHAPTER THREE
3.0 Construction
3.1 basic designs of an inverter
3.2 block diagram of the system
3.3 modified sine wave inverter circuit
3.4 description of components used
3.5 parts list
3.6 How to Choose A Right Inverter And Battery
3.7 How to choose the best inverter battery
CHAPTER FOUR
RESULT ANALYSIS
4.0 Construction Procedure and Testing
4.1 Casing and Packaging
4.2 Assembling of Sections
4.3 Testing of System Operation
4.4 Cost Analysis
CHAPTER FIVE
5.0 Conclusion
5.1 Recommendation
5.2 References
CHAPTER ONE
1.0 INTRODUCTION
All modern engineering system include certain aspects of control systems at some point in their broadcast sense, control engineering and the associated theory are concerned with the means by which systems may be made to behave an a desired way.
The system on this thesis is a DC – AC converter, which is an apparatus which is used for conversion of Direct Current to Alternating Current or signal.
In our country, this equipment is not all that in used not because it is not important but because people never give it a thought as per the construction and design.
It is meant, use with a 12v lead acid battery. If it’s in a car for example a suitable output voltage of 220v AC is obtainable.
This output voltage of 220v AC can be used for powering small electrical appliances such as light, electric fans, radio, soldering iron etc.
However, it is worthwhile that AC operated with this appliance is nothing comparable to the AC generated by big generators. This is so because the voltage and power are less in terms of AC generation duration. This appliance is therefore suitable for short time replacement for the real AC generation especially in the remote areas and install where electrical appliances are sold and the need might arise for it to be tested and certified good.
Another main area where this equipment can be of great utility is in communication system, in a situation where there is constant AC power supply failure e.g in offices, DC – AC converter is need and in such cases can be used as a light sources.
Most industries in the country do not make use of DC – AC converter because they are thought to be costly with respect to the task they perform. However, putting into consideration the task this appliance can be used for, it can be concluded that it is cheaper. The construction is simple, cheaper easy to operate and portable. The usefulness of this device and the function cannot to be over emphasize now in our economic situation and also when our power generating authority (NEPA).
In these times when control and monitor a complex field engineering operations have gone computer based, a failure of AC power supply to communication equipment means work stoppage and to some small scale industries a lot of economic and material losses avoidable. To this end, the equipment (DC-AC Converter) is incorporated to an impulse sealer machine which has about 3 sections where the,
First stage is of the dimmer switch with regulates, the rate at which the power flow is needed. The second stage being the main switch(s) which controls the primary side, secondary side of the transformer, the stage 3 comprise of the element made of construction wire which does or finishes the work needed for the machine.
1.2 OBJECTIVE OF THE STUDY
The objective of this project is to design and construct an inverter which can be powered from the source of 12V battery which incorporated its battery charger. The battery charger is used to charged 12 volts battery. This inverter is capable of operating a wide variety of loads; electronic and household items including but not limited to TV, VCR, and satellite receiver, computers, and printers.
1.3 SIGNIFICANCE OF THE PROJECT
- high quality and inexpensive; using modified square wave; output correction waveform; relatively stable; suitable for ordinary personal users with TV, fan, lamp, computer, hot pot
- The efficiency of an AC is enhanced since the start/stop cycles are eliminated in a DC Inverter AC. The AC does not operate at full power, but still maintains the desired temperature. This is another reason why these ACs can still save energy even if there are regular power outages.
- Inverter ACs are cheaper to operate in almost all types of conditions.
- Quicker cooling or heating (based on feature availability) can be achieved since an inverter AC can pull the required current on its own to increase initial cooling or heating. The inverter AC can calculate the current draw by using the indoor and outdoor temperature difference.
- DC Inverter ACs don’t put extra load on its power supply. Therefore you don’t see fluctuations in electricity caused by them.
- The life of components (used in the AC and other electrical household components) is increased due to the same reason i.e. gentle power draw.
- DC Inverter ACs are much quieter compared to conventional ones. The outdoor unit usually makes far less sound as the unit is operating at a reduced rate.
1.4 PROBLEM/ LIMITATION OF THE PROJECT
- lack of power, can not run the appliances with same power labeled; it’s easy to damage the machine if customers are not familiar with the operation, the user needs to strictly follow the manufacturers’ instructions.
- DC Inverter ACs cost more. Even without the dual-mode function, they still come with high price tags.
- The built-in circuit becomes far more complex due to multiple conversions from AC (Alternating Current) to DC (Direct Current) and back to AC (Alternating Current). 3-DC, 4-D or All DC inverter ACs have even more conversions taking place as there are more components working on DC.
- Repair costs increase as components are more sophisticated and as a result, more expensive. They require more effort to build or repair.
- Response Time: The inverter shall respond to any line voltage variation in 1/2 cycle while operating linear or non-linear loads, with a load power factor of 0.60 of unity. Peak detection of the voltage sine wave shall not be permitted to avoid inaccurate tap switching due to input voltage distortion.
- Operating Frequency: The inverter shall be capable of operating at +10% to -15% of the nominal frequency, 50Hz.
- Rating: this device shall be rated at 3.5kVA.
- Access Requirements: The inverter shall have removable panels on the front, rear and sides as required for ease of maintenance and/or repair.
- Metering: An input meter is provided to display line voltages.
- Ventilation: The inverter isolation transformer shall be designed for convection cooling. If fan cooling is required for the MOSFET used.
1.5 SCOPE OF THE PROJECT
A power inverter, or inverter, is an electronic device or circuitry that changes direct current (DC) to alternating current (AC). The input voltage, output voltage and frequency, and overall power handling depend on the design of the specific device or circuitry.
inverter takes current from a battery, which is usually 12 Volt Dc, as batteries usually produce DC power, and then after passing this current through a 50Hz processor, it converts it into the normal 220 volt Ac which is commonly used.
1.5 TYPES OF INVERTER
Inverters can be categorized the following ways:
– Stand-alone (also known as Off-Grid):
Used in isolated systems where the inverter draws its DC energy from batteries charged by solar arrays and/or other sources, such as wind turbines, hydro turbines etc. Normally these do not interface in any way with the utility grid, and as such are not required to have anti-islanding protection.
– Grid-Tied:
These systems match their phase with a utility-supplied sine wave. Grid-tie inverters are designed to shut down automatically upon loss of utility supply (referred to as anti-islanding protection). They do not provide backup power during utility outages. In Ontario, any solar arrays that feed the utility grid (under the FIT/microFIT programs for example), are required to have anti-islanding protection.
– Battery Backup:
These are special inverters which are designed to draw energy from a battery, manage the battery charge via an onboard charger, and export excess energy to the utility grid. These inverters are capable of supplying AC energy to selected loads during a utility outage, and are required to have anti-islanding protection.
1.7 APPLICATION OF THE PROJECT
Inverters find diverse uses and applications in daily life, due to their function of converting DC to AC. The applications are as follows:
DC power source utilization
Inverter designed to provide 115 VAC from the 12 VDC source provided in an automobile. The unit shown provides up to 1.2 amperes of alternating current, or enough to power two sixty watt light bulbs.
An inverter converts the DC electricity from sources such as batteries or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage.
Uninterruptible power supplies
An uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when main power is not available. When main power is restored, a rectifier supplies DC power to recharge the batteries.
Electric motor speed control
Inverter circuits designed to produce a variable output voltage range are often used within motor speed controllers. The DC power for the inverter section can be derived from a normal AC wall outlet or some other source. Control and feedback circuitry is used to adjust the final output of the inverter section which will ultimately determine the speed of the motor operating under its mechanical load. Motor speed control needs are numerous and include things like: industrial motor driven equipment, electric vehicles, rail transport systems, and power tools. Switching states are developed for positive, negative and zero voltages as per the patterns given in the switching Table 1.The generated gate pulses are given to each switch in accordance with the developed pattern and thus the output is obtained. Thus the Simulink model and output voltage waveform of Symmetric multilevel inverter.
Power grid
Grid-tied inverters are designed to feed into the electric power distribution system. They transfer synchronously with the line and have as little harmonic content as possible. They also need a means of detecting the presence of utility power for safety reasons, so as not to continue to dangerously feed power to the grid during a power outage. The subsystem which includes sinusoidal and triangular subsystem brief about the comparison of sine wave which is the modulated signal and is compared with carrier signal. When the reference signal is greater than or equal to carrier signal, then the output waveform is above the reference and otherwise it will be below the reference.
Solar
A solar inverter can be fed into a commercial electrical grid or used by an off-grid electrical network. Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection. Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid. They are grid tie designs by default.
Induction heating
Inverters convert low frequency main AC power to higher frequency for use in induction heating. To do this, AC power is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power. Due to the reduction in the number of DC Sources employed the structure become more reliable and the output voltage has higher resolution due to increase in the number of steps and the reference sinusoidal voltage can be better achieved. This configuration recently becomes very popular in AC power supply and adjustable speed drive applications. This new inverter can avoid extra clamping diodes or voltage balancing capacitors There are three kinds of level shifted modulation techniques, namely;
Phase Opposition Disposition (POD)
Alternative Phase Opposition Disposition (APOD) Phase Disposition (PD)
HVDC power transmission
With HVDC power transmission, AC power is rectified and high voltage DC power is transmitted to another location. At the receiving location, an inverter in a static inverter plant converts the power back to AC. The inverter must be synchronized with grid frequency and phase and minimize harmonic generation.
Electroshock weapons
Electroshock weapons and tasers have a DC/AC inverter to generate several tens of thousands of V AC out of a small 9 V DC battery. First the 9VDC is converted to 400–2000V AC with a compact high frequency transformer, which is then rectified and temporarily stored in a high voltage capacitor until a pre-set threshold voltage is reached. When the threshold (set by way of an airgap or TRIAC) is reached, the capacitor dumps its entire load into a pulse transformer which then steps it up to its final output voltage of 20–60 kV. A variant of the principle is also used in electronic flash and bug zappers, though they rely on a capacitor-based voltage multiplier to achieve their high voltage.
