Inductor

Inductor classification:

1. Classification by structure:

• Air core inductor: No magnetic core, only wound by wire. Suitable for high-frequency applications.
• Iron core inductor: Use ferromagnetic materials as magnetic core, such as ferrite, iron powder, etc. This type of inductor is usually used in low-frequency to medium-frequency applications.
• Air core inductor: Use air as magnetic core, with good temperature stability, suitable for high-frequency applications.
• Ferrite inductor: Use ferrite core, with high saturation flux density, suitable for high-frequency applications, especially in RF and communication fields.
• Integrated inductor: Miniature inductor manufactured by integrated circuit technology, suitable for high-density circuit boards.

2. Classification by use:

• Power inductor: Used in power conversion circuits, such as switching power supplies, inverters, etc., capable of handling large currents.
• Signal inductor: Used in signal processing circuits, such as filters, oscillators, etc., suitable for high-frequency signals.
• Choke: Used to suppress high-frequency noise or prevent high-frequency signals from passing, usually used in RF circuits.
• Coupled inductor: used for coupling between circuits, such as transformer primary and secondary coils.
• Common mode inductor: used to suppress common mode noise, usually used for protection of power lines and data lines.

3. Classification by packaging form:

• Surface mount inductor (SMD/SMT): suitable for surface mount technology, with compact size, suitable for high-density circuit boards.
• Through-hole mount inductor: installed through through-holes on the circuit board, usually with high mechanical strength and heat dissipation performance.
• Wirewound inductor: inductor made by traditional manual or automatic winding methods, suitable for high current applications.
• Printed circuit board (PCB) inductor: inductor made directly on the circuit board, usually used for miniaturization and low-cost design.

The main role of inductors:

1. Filtering: Inductors combined with capacitors can form LC filters, which are used to smooth the power supply voltage, remove AC components, and provide more stable DC voltage.

2. Energy storage: Inductors can store magnetic field energy, provide instantaneous energy when the power is interrupted, and are used in energy conversion and storage systems.

3. Oscillator: Inductors and capacitors can form LC oscillators, which are used to generate stable AC signals and are commonly found in radio and communication equipment.

4. Impedance matching: In RF and communication circuits, inductors are used for impedance matching to ensure effective signal transmission and reduce reflection and loss.

5. Choke: In high-frequency circuits, inductors are used as chokes to block high-frequency signals while allowing low-frequency signals to pass.

6. Transformer: Inductors can be used with other inductors to form transformers, which are used to change voltage levels or isolate circuits.

7. Signal processing: In signal processing circuits, inductors are used for signal division, coupling, and filtering to help separate signals of different frequencies.

8. Power conversion: In switching power supplies and DC-DC converters, inductors are used to regulate voltage and current for efficient energy conversion.

9. Protection circuits: Inductors can be used to protect circuits from transient overvoltages, such as using chokes on power lines to suppress spike voltages.

10. Noise suppression: In sensitive electronic devices, inductors can be used to suppress electromagnetic interference (EMI) and radio frequency interference (RFI), reducing signal distortion and interference.

Inductor manufacturing process:

1. Design and planning:

• Determine the specifications of the inductor, including inductance value, operating frequency, rated current, etc.
• Select the appropriate core material and wire type.

2. Core preparation:

• Select the core material, such as ferrite, iron powder, ceramic, etc.
• Cut or shape the core according to the design requirements.

3. Winding the coil:

• Prepare the wire, usually copper wire or silver-plated copper wire.
• Wind the coil, determine the number of turns of the coil and the diameter of the wire according to the required inductance value and operating frequency.
• You may need to use a winding machine to automate this process.

4. Assembly:

• Mount the wound coil on the core.
• If you use an iron core inductor, you need to ensure close contact between the coil and the core.
• For air core inductors, the coil can be wound directly on the skeleton.

5. Testing and Adjustment:

• Test the inductor’s inductance, DC resistance, quality factor and other key parameters.
• Adjust the number of turns of the coil or the position of the core to achieve the required inductance.

6. Packaging:

• Package the inductor, usually using plastic or epoxy resin to provide physical protection and reduce electromagnetic interference.
• For surface mount inductors, special packaging may be required to adapt to the SMT process.

7. Quality Control:

• Perform a final quality check on the finished product to ensure that all parameters meet the specifications.
• Perform aging tests to ensure that the performance of the inductor is stable after long-term operation.

8. Marking and Packaging:

• Mark the necessary information on the inductor, such as inductance value, rated current, etc.
• Pack the finished product and prepare it for shipment.