How a Simple Boost Converter Work?

A boost converter is a DC-DC converter that steps up a lower input voltage to a higher output voltage.

In this article I demostrate how a basic boost converter works. Boost converter are fundamental parts of mobile devices powered by batteries.

Components of a Simple Boost Converter:

Inductor (L): Stores energy and is the key component in the voltage boost process.

Diode (D): Ensures that current flows in one direction, directing energy to the output.

Switch: Controls when the inductor is charged and discharged.

Capacitor (C): Stabilizes the output voltage by smoothing fluctuations.

Values of Components:

Inductor: I made the inductor in this circuit using 0.5mm copper wire and a 4mm bolt.

Diode: 1N4007

Switch: A simple push button

Capacitor: 150 µF, 53V

Note: In practical circuits, MOSFETs are commonly used as switching components. A controller (PWM signal) is typically used to regulate the switch by turning it on and off to adjust the voltage.

To construct the inductor, follow these steps:

1. Insulation: Begin by wrapping a paper label around the 3mm bolt to provide insulation.
2. Winding the Coil: Carefully wind the copper wire around the bolt as evenly as possible. Try to keep the turns tight and uniform.
3. Layer Insulation: After completing each layer of winding, repeat the paper wrapping process to insulate the layers from each other.
4. Number of Layers: Repeat this process for 3 to 5 layers.

By the end of this process, you will have an inductor with an approximate inductance of 300-350 microhenries.

Placing and Soldering Components on Perforated Board:

Begin by placing each component (inductor, diode, switch, and capacitor) on the perforated board according to the schematic diagram. Make sure the leads of the components are inserted into the appropriate holes.

Double-check the layout to ensure all components are correctly positioned and their leads are properly aligned with the circuit connections.

Once the components are in place, begin soldering the leads to the copper traces on the underside of the board. After soldering, use wire cutters to trim any excess lead length for a clean and neat finish.

Inspect all solder joints to ensure they are strong and free of cold joints (dull or cracked solder), which can cause unreliable connections.

Switch Closed (Transistor On): When the switch is on, the current flows through the inductor, building up a magnetic field and storing energy.

Switch Open (Transistor Off): When the switch is off, the stored energy in the inductor is released. The voltage increases as the magnetic field collapses, and the diode directs this higher voltage to the output. The capacitor helps smooth the output, providing a stable higher voltage to the load.

Use a multimeter to measure the output voltages. You should observe a significant voltage increase at the output.

Step-by-step breakdown of the circuit in action:

Powering the Circuit:

When a DC input voltage (e.g., 3.7V from a lithium-ion battery) is supplied to the circuit, the inductor (L) begins to store energy.

Switch Closed (Charging Phase):

When the switch (transistor or push button) is closed, current starts flowing through the inductor. This flow of current generates a magnetic field around the inductor, allowing it to store energy.

During this phase, the diode is reverse biased, preventing current from reaching the output, and the stored energy is held in the inductor.

Switch Open (Discharging Phase):

When the switch opens, the current flow through the inductor is interrupted. The magnetic field that was created begins to collapse, and the stored energy is released.

As the energy is released, the inductor produces a voltage spike, which is higher than the input voltage. This higher voltage is directed through the diode to the output.

Voltage Boost:

The released energy, combined with the input voltage, results in a higher output voltage than the original input. This is the boost action of the converter.

The capacitor at the output smooths out fluctuations, ensuring a stable DC voltage.

Resulting Output:

We obtained an output voltage of around 12V. This value will decrease when a load is connected

It's also a good idea to test the circuit under different loads to see how well the boost converter performs and how stable the output voltage remains.

Switching Frequency:

In a more advanced version of this circuit, a PWM signal (Pulse Width Modulation) is used to rapidly switch the transistor on and off. The frequency of switching directly affects the efficiency and the output voltage.

A well-optimized switching frequency ensures that the boost converter operates efficiently and maintains a consistent output voltage under varying load conditions.