The demand for portable power solutions is ever growing especially in scenarios where access to mains outlets is limited such as in cars, trailers or cottages.
Constructing your own DC/AC power inverter provides a versatile solution to power various household appliances like radios, DVD players, electric shavers and more.
What is a IC 555 Inverter Circuit:
An IC 555 inverter circuit is a circuit that drives a power inverter by creating an oscillating waveform using the well-known IC 555 circuit.
A device that converts direct current DC power into alternating current AC power is called a power inverter.
Because of its flexibility and ease of use the IC 555 is often used in electrical circuits.
Using essential parts like the 555 IC, MOSFETs, transformers and heatsinks this post will guide you through building a power inverter.
Circuit Working:
Parts List:
| Component Type | Description | Quantity |
|---|---|---|
| Resistors | ||
| 4.7k 1/4 W CFR | 1 | |
| 120k 1/4 W CFR | 1 | |
| 2.7k 1/4 W CFR | 1 | |
| 10k 1/4 W CFR | 1 | |
| 470 ohm 1/4 W CFR | 1 | |
| Capacitors | ||
| PPC 100nF | 2 | |
| Electrolytic 2200μF 25V | 1 | |
| Semiconductors | ||
| Transistor BC547 | 1 | |
| MOSFET IRF540 | 2 | |
| IC 555 | 1 | |
| Transformer 9-0-9V / 5A / 220V | 1 | |
| Battery 12V / 25Ah | 1 |
Frequency Generation with 555 IC:
To generate a stable 50Hz frequency a famous 555 IC is used.
The frequency is calculated by the values of resistance Rx and capacitor Cx.
The formula for frequency (f) is given by:
f = 1 / 0.693 × ( Rx + 2 × R1 ) × Cx
where,
- f is a oscillation frequency (f)
- Rx resistor controls the timing capacitors Cx rate of charging and discharging in combination with R1
- R1 by affecting the capacitors rate of charging and discharging R1 affects the oscillation frequency in combination with Rx.
- Cx capacitor creates the timing network that regulates oscillation frequency along with Rx and R1.
MOSFETs and Logic Inverter:
Two N type MOSFETs act as switches in the inverter.
One is directly driven by the 555 IC while the other is controlled through a logic inverter using a BC547 transistor.
Effective power switching is achieved by using of MOSFETs.
Correct isolation and grounding are both should be taken seriously in the overall circuit design.
Transformer Selection:
Choose a transformer mains having two 12V secondary windings.
The transformer should be built to support the highest possible load.
The following is the formula for power P:
P = V × I
where:
- P is power
- V is voltage and
- I is current.
Heatsink Considerations:
Make that the power transistors heatsink is the right size for the projected load.
To avoid unexpected grounding the heatsinks needs to be installed on isolation pads.
As a second choice separate transistor heatsinks can be used, as long as they are not in contact with ground or one another.
Power Supply and Frequency Adjustment:
Maintain a sufficiently hard 12V supply with a voltage range of about 11 to14V.
Integrate a proper fuse in series with the power input for safety.
For applications not reliant on a 50Hz frequency a higher frequency 100 to 300Hz is used to reduce standby power.
Adjust the frequency by modifying the values of Rx and Cx.
MOSFET Selection:
Select the appropriate MOSFET based on the load requirements:
IRFZ44 for loads up to 200W
IRFZ48 for loads up to 350W
IRF3205 for loads up to 600W Combine multiple IRF3205 transistors in parallel for outputs exceeding 600 watts.
The IRF1405 is also recommended for its excellent parameters.
Frequency Generation:
A 555 IC should be placed on a breadboard.
As per the chosen frequency values wire Rx and capacitor Cx to the 555 IC.
For the required frequency calculate the resistor and capacitor values using the previously given formula.
MOSFETs and Logic Inverter:
Connect two N type MOSFETs to the breadboard.
Connect one MOSFET directly to the 555 IC and the other through a BC547 transistor acting as a logic inverter.
Ensure proper grounding and isolation to prevent unwanted interference.
Transformer Connection:
While connecting the transformer mains to the circuit remember to use both of the 12V secondary windings.
Consider the expected maximum load while sizing the transformer.
Heatsink Integration:
Mount the power transistors on the heatsink.
Use isolation pads to prevent grounding.
Alternatively, use separate heatsinks for each transistor ensuring they do not touch each other or ground.
Power Supply and Fuse:
Include a 12V power supply that can handle voltages between 11 and 14V.
To improve safety connect the correct fuse in series with the power input.
Frequency Adjustment and MOSFET Selection:
When needed change the values of Rx and Cx to adjust the frequency.
Using the given ideas select the proper MOSFET based on the expected load.
Warning:
Working with the power inverter requires extreme care because the output voltage can be dangerous.
Even though the input is safe it might be highly hazardous to touch both output terminals.
Although the output voltage is grounded one should maintain caution.
The user bears all risk when building and using the inverter while the writer is not responsible for any damages caused.
When handling electrical components always put safety first and follow the right procedures.
Conclusion:
A simple IC 555 inverter circuit for portable power applications is designed successfully by following the above instructions and obeying the safety rules.
During construction always make sure your connections are safe and make sure the insulation is satisfactory by putting safety first.