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DC DC converter working principle

DC DC converter working principle

DC DC circuit principle: DC DC is the abbreviation of English DC to DC, so DC-DC circuit is a circuit that converts DC power into different voltage values. DC-DC is a branch of switching power supply technology. Switching power supply technology includes two ff branches of AC-DC and DC-DC. The DC-DC circuit is divided into functions according to functions: Boost converter: A circuit that converts a low voltage into a high voltage.

DC-DC circuit principle:

DC-DC is an abbreviation for English DC to DC, so the DC-DC circuit is a circuit that converts a DC power source into different voltage values. DC-DC is a branch of switching power supply technology. Switching power supply technology includes two ff branches of AC-DC and DC-DC. The DC-DC circuit is divided into functions according to functions:

Boost converter: A circuit that converts a low voltage into a high voltage.
Buck converter: A circuit that converts a high voltage into a low voltage.

Inverter: A circuit that changes the polarity of a voltage, and has a positive power supply to a negative power supply, and a negative power supply to a positive power supply.

There are three main branches, of course, there are functions such as boost reverse and buck boost in the same circuit.

The basic circuits of the DC DC converter include a boost converter, a buck converter, and a buck-boost converter.

The schematic diagram of the buck converter is shown in Figure 1. When the switch is closed, the voltage applied across the inductor is (Vi-Vo). At this time, the inductor is excited by the voltage (Vi-Vo), and the magnetic flux increased by the inductance is: Vi-Vo)*Ton.

When the switch is turned off, due to the continuous output current, the diode VD becomes conductive, the inductor is magnetized, and the magnetic flux with reduced inductance is: (Vo)*Toff.

When the state in which the switch is closed and the switch is off is balanced, (Vi-Vo)*Ton=(Vo)*Toff, since the duty ratio D<1, Vi>Vo, the buck function is realized.

Buck converter schematic
Figure 1 Buck converter schematic

The schematic diagram of the boost converter is shown in Figure 2. When the switch is closed, the input voltage is applied to the inductor. At this time, the inductor is excited by the voltage (Vi), and the magnetic flux of the inductance is increased by: (Vi)*Ton.

When the switch is turned off, due to the continuous output current, the diode VD becomes conductive, the inductor is magnetized, and the magnetic flux with reduced inductance is: (Vo-Vi)*Toff.

When the state in which the switch is closed and the switch is off is balanced, (Vi)*Ton=(Vo-Vi)*Toff, since the duty ratio D<1, Vi.

Boost converter schematic
Figure 2 Boost converter schematic

The buck-boost converter, the opposite polarity principle is shown in Figure 3. When the switch is closed, the inductor is excited by the voltage (Vi), and the magnetic flux of the inductance is: (Vi) * Ton; when the switch is open, the inductor For magnetic shaving, the magnetic flux with reduced inductance is: (Vo)*Toff. When the state in which the switch is closed and the switch is off is balanced, the increased magnetic flux is equal to the reduced magnetic flux, (Vi)*Ton=(Vo)*Toff, depending on the Ton ratio Toff value, possibly Vi< Vo, or possibly Vi >Vo.

Schematic diagram of the buck-boost converter
Figure 3 Schematic diagram of the buck-boost converter

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