Previously I wrote about TL494 based inverter designed for low frequency(50/60Hz) intended for large and heavy iron-core transformer. After revisiting it and thought I should make another TL494 based inverter which is more advanced high frequency (SMPS) inverter. The previous TL494 inverter was a simple one which used complementary power transistors TIP41 and TIP42 with fixed 50% duty cycle. Here I will be showing a professional 12V DC to 220V AC inverter designed with two BC327 driver stage and four IRFZ44N MOSFETs based output power stage.
Update:
The 2nd part of this inverter design: DIY 12V DC to 220V AC Inverter using TL494 PWM. See the 3rd part is here: How 12V to 220V AC TL494 Inverter Works - Simulation
Circuit Diagram
The following shows the circuit diagram of 12V DC to 220V AC inverter using TL494 PWM controller IC.
The design step is as follows:
Setting up the TL494 PWM Controller
Begin by placing the TL494 IC, the heart of the PWM controller. Connect Pin 1 (1IN+) and Pin 2 (1IN-) to the common rail. Place a 15nF timing capacitor (C1) between Pin 5 (CT) and Ground to set the switching frequency. Finally, add a 5k Variable Resistor (RV1) and a 1k resistor (R1) to Pin 6 (RT); this allows for fine-tuning the frequency specifically for the ferrite transformer.
Power and Ground Railing
Connect the input connector J1 and bridge Pin 7 (GND) to the negative rail. Ensure Pin 12 (VCC) and Pin 11 (C2) are tied to the 12V supply rail. For proper push-pull operation, connect Pin 13 (OCTRL) directly to Pin 14 (REF).
Driver Stage with BC327
Place two 1k pull-down resistors (R2, R3) on the output lines from Pins 9 and 10. Add two BC327 PNP transistors (Q1, Q2) and two 1N4148 diodes (D1, D2) to act as the gate drivers. The emitters of these transistors will drive the MOSFET gates through 47-ohm resistors (R4, R5).
MOSFET Power Bank
Add the power MOSFETs using four IRFZ44N units (Q3, Q4, Q5, Q6) arranged in two parallel pairs. Each MOSFET gate must have its own 47-ohm resistor to ensure balanced switching and prevent overheating. Complete this stage by joining the sources of all MOSFETs to the common ground rail.
Final Transformer Assembly
Place the Step-Up Transformer (TR1). The center tap of the primary winding connects directly to the +12V DC input. Connect the drains of one MOSFET pair to one side of the primary, and the other pair to the opposite side. Finally, add a large 1000uF electrolytic capacitor (C2) across the power lines to filter out switching noise and stabilize the voltage.
🛠️ Components Used in This Design:
Battery 12V DC
Oscillator IC TL494
MOSFETs IRFZ44N (x4)
BJT BC327(x2)
Transformer High-Frequency Ferrite Core Transformer
Diodes 1N4148(x2)
Capacitors 1000µF, 15nF
Resistors 1k (2), 47Ω(x4)
How to Design 12V DC to 220V AC Inverter Circuit Schematic in Proteus
The following video shows how to design the inverter circuit in Proteus
Related resources:
