Project overview


Inverter Design


Introduction:

DC-AC Inverters are common household devices. This device is commonly based on H-Bridge circuit. SG-3525 IC is used to drive the mosfets by applying 12V DC source (i.e. a battery) on input side and through some process like using DC Booster converter and step up transformer on output side produces 220V AC on the output side. H-Bridge circuit is developed with the help of IC SG3525 which is a regulating pulse width modulator IC. SG3525 is a single package multi function PWM generator IC. The IC we have used is doing this job of driving the mosfets, and each time it operates two mosfets for half of the time to pass the signals and second time for remaing tow respectively. Secnodly we have used current module to sense current and voltage at both ends of circuitry and finally displayed that results on LED using Ardunio. we have discussed each of these toipcs below respectivey.

Nowadays majority of things in our daily life needs electricity, there are so many home appliances which run on AC power supply. Also there are some cases of load shading where we use solar panel and other electrolytic batteries to power the appliances thus we have to first change the dc voltage into ac this is where we do require an inverter.


Delegation of Tasks:

Task Done by
Research on the project Individually
Schematic and PCB design Muhammad Punhal
Ardunio coding Naqcho Ali
Interfacing with display using Ardunio Muhammad Punhal
Collecting the bill of materials & some other peripherals Muhammad Punhal
PCB Soldering Naqcho Ali
Testing the inverter Naqcho Ali
Case design in Solid Works (in process) Muhammad Punhal



High Level Design:

The very first thing came in our mind was the working process of our designed PCB . We brainstromed an got the solution by using our thinking caoability that what to use first and next to work out the sketch. this design is mind map of our complete project.
The very first thing is the dc power source here we have used a 12volts battery, in order to enhance the dc voltage we have used the dc booster. Mosfets are used in the inverter circuit which is responsible for the output signal, two mosfets simultaneously works to make the upper half of the waveform while another two mosfets operate to make the second half of the waveform. The ic we have used is doing this job of driving these mosfets. Another major components that we have used is the microcontroller which is used to operate the current sensors and the lcd . The sensors read a raw value from the input as well as from the output and then send to the analog pins of the microcontroller which then are used in calculation to find out the current flowing from the output and input sides. the remaing main component is the transformer, which is served in stepping up the signal that is at the output terminal of the inverter circuit





Design requirements:

We are going to design a small portable inverter which can produce 500W, provides user interface for power input / output user interface. So for that we will use step up transformer which will boost the power from 12V Dc applied source to the expected result of 220V Ac. For achieving this process we need some tools like PCB design using Eagle and fabrication through SRM20 machine which is rightly avilable at Sukkur Fab Lab. And finally go for prototype of our final product with the help fo Laser cut.


  • Most importantly SG3525 IC:

  • Current Module

  • The Micro-controller (Ardunio):

  • Display


1. SG3525 IC:

This is a regulating pulse width modulator IC, which plays an important role in driving the circuitry and switching the power at Mosfets gates, from where we get output. Pin#11 and #14 (output A and output B): These are the two outputs of the IC which operate in a totem pole configuration or simply in a flip flop or push pull manner. External devices which are intended for controlling the converter transformers are integrated with these pinouts for implementing the final operations.




Main Technical Features:


  • Operating voltage = 8 to 35V
  • Error amp reference voltage internally regulated to 5.1V
  • Oscillator frequency is variable through an external resistor within the range of 100Hz to 500 kHz.
  • PWM pulses are controlled through latching for inhibiting multiple pulse outputs or generation.
  • Output supports a dual totem pole driver configuration.
  • Facilitates a separate oscillator sync pinout.
  • Shut down facility features a pulse by pulse shutdown enhancement.
  • Input under voltage shut down feature also is included.


Below are given bookmarked links only click to see documentation and download datasheet of IC: