what kind of transformer is used in inverters?

Inverters are used to convert DC (direct current) to AC (alternating current), and the choice of components in an inverter circuit is crucial for its functionality and efficiency. Below is an explanation of the components, the type of transformer typically used in inverters, as well as details on the CD4047 IC, IRFZ44 MOSFET, and a 12-0-12/1A secondary transformer.

Transformer Used in Inverters

Inverters commonly use step-up transformers to convert low-voltage DC from batteries to higher-voltage AC. 

The transformer used in inverters typically has the following characteristics:

1. Type:

   • Center-tapped Transformer: A center-tapped transformer is often used, which provides two equal voltages from a center-tap connection. This allows for the generation of both positive and negative halves of an AC waveform.
   • Toroidal Transformer: Toroidal transformers are also used for their efficiency, reduced electromagnetic interference, and compact size.

2. Specifications:

   • Primary Winding: Connected to the inverter's output (usually low voltage).
   • Secondary Winding: Provides higher AC voltage output (e.g., 220V or 110V AC).
   • Power Rating: Depends on the application, ranging from a few watts to several kilowatts.

12-0-12/1A Secondary Transformer

The 12-0-12/1A Secondary Transformer is a type of center-tapped transformer with the following specifications:

• Voltage Rating: 12-0-12 volts AC (24V center-tapped).
  • Center Tap: The center tap divides the secondary winding into two equal halves, each providing 12V. The total across both ends is 24V AC.
• Current Rating: 1 Ampere.
• Usage: Often used in low-power inverter circuits, battery chargers, power supplies, and audio amplifiers.
• Role in Inverters:
  • The transformer steps up the voltage from a low DC level (converted to AC by the inverter circuit) to a higher AC voltage suitable for powering AC appliances.

CD4047 IC

The CD4047 is a CMOS-based monostable/astable multivibrator IC used in inverter circuits for generating square wave signals. Here's an overview of its features:

• Operating Modes:
  • Monostable Mode: Generates a single pulse of a specific duration.
  • Astable Mode: Generates continuous square waves, which is used for clock generation in inverter applications.
• Applications:
  • Inverter Circuits: Acts as an oscillator, providing the necessary timing and control signals to drive MOSFETs or transistors.
  • Timing Applications: Pulse generation, frequency generation.
• Features:
  • Low Power Consumption: CMOS technology ensures low power usage.
  • Wide Operating Voltage Range: 3V to 15V.
  • Adjustable Frequency: Frequency of oscillation can be adjusted using external resistors and capacitors.

CD4047 Inverter Circuit Example

Here's a basic schematic of how the CD4047 IC is used in a simple inverter circuit:

Components:

• CD4047: Used as an oscillator to generate a square wave.
• IRFZ44 MOSFETs: Used to drive the transformer.
• Transformer: Steps up the voltage to AC output.
• Capacitors and Resistors: Set the frequency of oscillation.

IRFZ44 MOSFET

The IRFZ44 is an N-channel MOSFET commonly used in inverter circuits due to its high current-carrying capacity and efficiency. Here are its key characteristics:

• Voltage Rating: V_DS = 55V (Drain-Source Voltage).
• Current Rating: I_D = 49A (Continuous Drain Current).
• R_DS(on): Low on-state resistance, ensuring minimal power loss.
• Applications:
  • Switching Applications: Used as a switch to drive loads.
  • Inverter Circuits: Acts as a power switch to convert DC to AC by switching the transformer.
• Gate Drive: Requires a gate-source voltage (V_GS) typically around 10V for full conduction.

Working of Inverter with CD4047 and IRFZ44

1. Oscillator Stage (CD4047):

   • The CD4047 generates a square wave signal in astable mode. The frequency of this signal can be set using external resistors and capacitors.
   • The square wave output is used to drive the gates of the IRFZ44 MOSFETs.

2. Driver Stage (IRFZ44):

   • Two IRFZ44 MOSFETs are used in a push-pull configuration to alternately drive the two halves of the transformer's primary winding.
   • The MOSFETs switch the DC input, creating an alternating current through the transformer.

3. Transformer Stage:

   • The transformer steps up the low-voltage AC to the desired high-voltage AC output (e.g., 220V AC).
   • The center tap of the transformer is connected to the DC source, while the two MOSFETs switch the other ends.

Application Example: Simple 100W Inverter

Here's a practical example of a simple inverter circuit using a 12-0-12/1A transformer, CD4047, and IRFZ44:

Circuit Diagram:

Explanation:

1. CD4047 Configuration:

   • R1 and R2: Set the frequency of oscillation.
   • C1: Works with R1 and R2 to set the timing.
   • Pins A and B: Provide complementary square wave outputs to drive the MOSFETs.

2. IRFZ44 Configuration:

   • The MOSFETs switch the current through the transformer's primary winding.
   • R4 and R5: Current limiting resistors for MOSFET gates.

3. Transformer:

   • 12-0-12/1A transformer steps up the voltage to 220V AC.

Output:

• AC Output: The circuit can provide around 100W of power at 220V AC, suitable for powering small appliances.

See also the video that animates how inverter circuit works,

Conclusion

Inverter circuits using CD4047 ICs and IRFZ44 MOSFETs are popular for their simplicity and efficiency. The 12-0-12 transformer plays a critical role in stepping up the voltage to usable levels for AC appliances. By carefully selecting and configuring these components, you can build an effective inverter for various applications.

Resources

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