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How does DC DC converter work?

All about DC/DC converter

DC-DC voltage module converting are widely used in electronic and computer engineering and automation, telecommunications, etc.

DC-DC converter is used to receive the other output voltage as the input. It may be higher than the original, or below.

Types of DC DC Converter

There are many different dc dc converters on the market, which are often used by consumers.

  1. DC / DC converters without inductors.

This is capacitor voltage amplifiers. It based on pumping energy. This converters can reduce, thereby increase or leave most voltage as the input. They are used for various amplifiers, voltage sensors, interfaces, where a negative voltage is needed.

  1. DC / DC converters with the inductors.

Very popular are those who don’t have galvanic isolation between input and output. This converter is insulated by a single power supply which produces constant current from the AC voltage. Depending on the key position, the voltage can be raised, lowered, convert voltage in the opposite polarity. Key elements often act bipolar transistors isolation gate (IGBT) and various types of field effect transistors (FET),

There is among converters with inductance:

  • Step-down switching converter. The key has a transistor controlled rectangular pulses, which regulates the pulse width modulator.
  • Switching Boost DC-DC converter. Its features will be discussed below.
  • Converter with a change of polarity of the input and output voltage. This type of device is called inverting stabilizers. At the entrance we have a positive voltage, and in output it becomes negative. The bottom line is the polarity of the diode, buyout voltage changes polarity.
  • Any inverter output voltage. They are able to produce both high and low voltage at the output. Why do they need? For example, for use in communication schemes, where the voltage is given by Li-ion battery. They have voltage 3.3V. Eventually its operating voltage is reduced, and therefore it makes sense to translate the output to 3.3. An example of this is the Buck-boost DC DC converter from Terratel.

Buck-boost DC-DC converter input 35V-160V, 48V-24V output. Block Diagram

Multiple units DC-DC converter

3. DC / DC converter with galvanic isolation.

Used pulse transformers, buyout have 2 or more windings. At the same time there is no connection between the input and output circuit.

Such transformers potential difference between input and output is very large. They are used for the power supply pulse flashbulbs that the output voltage of about 400V have.

Principle of buck-boost DC-DC converters operation

We have 5 volts in input, and need to have more in output. There are several options how to achieve this. For example, you can charge a capacitor in parallel, and then switch them consistently. You need to do this very quickly, several times a second. Of course, in practice this is unrealistic, so there is special DC DC converters.

To understand how this works, imagine yourself a plumber.

Step 1 – Accelerate the turbine.

We need to accelerate the turbine. We open the flap and the water is drained simply by transferring part of its energy to the turbine, which begins to spin latter.
DC DC converters

Step 2 – Filling the pressure accumulator.

The flap is closed. But the water has nowhere to go, it had already dispersed, turbine unwind. Water can’t stop, and therefore through the valve of the water enters the pressure accumulator. And the rest is sent to the user, only this time with high pressure, to which alone it would not have developed. The valve also prevents water is not turned back.
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Step 3 – Getting energy from the pressure accumulator and accelerate the turbine.

Turbine speed begins to fall. Water can no longer push the valve, and the energy accumulated in the battery is sufficient. The valve opens and water begin run away, and the turbine spins up again. At the same time the consumer receives energy from the battery, so did not notice anything.
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And then everything is repeated.

Well, the principle is clear. Now let’s move from the plumbing to electronics.

Instead turbine we have inductive drosel. The transistor is used instead of valves that regulate the flow of water. Role of valve performs diode and the capacitor is thus a pressure accumulator.

And so it looks like DC DC Converter. How does it work? Everything is the same.

Step 1 – Accumulation of charge by inductance.

Switch is closed. Source produce current and delivers it to the spool.

How does DC DC converter work

Step 2 – Transfer of energy to the capacitor.

Switch is opened, but the coil has stockpiled energy in a magnetic field. Current tries to remain at the same level, but the extra energy from the coil pops out and the voltage jumps dramatically to knock diode and go further. This forms from 5 volt to 12. Part of the energy goes to the consumer, and the remainder is stuffed into the condenser.

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Step 3 – Energy storage in inductance and power transmission.

Key again closes and the energy again starts to be engraved in the coil. The consumer also still takes energy from the capacitor.

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