A buck converter steps down voltage to power a lower voltage load with high efficiency. Linear regulators are simple but inefficient. Buck-boost converters can function as both buck and boost converters for solar energy systems.
A buck converter is a converter that steps down the voltage that reaches a direct current (DC) load. For example, the output of a 24 volt (V) direct current (VDC) power source can be scaled down to power 12 volt equipment. A well-designed buck converter is able to deliver a constant output voltage under varying load conditions and maintain very low power dissipation, leading to high efficiency.
Linear regulators can be a simple solution for low power requirements. They make use of a series-passed power transistor which controls the current through the load to produce the constant DC output voltage. If a 50V DC supply uses a linear regulator to drive a 25V load at 1 ampere (A), the power through the load and the linear regulator will be 25 watts (W). This means that 50W is drained from the 50V power supply. The conversion efficiency is 50%, but if a buck converter is used and the power dissipation in the buck converter is 2.5W while the power at the load is still of 25 W, the efficiency is about 90%.
The buck converter is a DC-to-DC converter that works much like a switched-mode power supply (SMPS), controlling the duty cycle of a fixed-frequency square wave. When the load requires less current, the square wave “turn on” time is short, but when the load requires current very close to the SMPS limit, the “turn on” time exceeds 85%. Switched DC uses a fast switching diode in series inductor that uses inductive backflow to sustain energy transfer when the main driving element is turned off for short periods.
For an opposite application to that of the buck converter, the step-up boost converter (SUBC) is used. The SUBC generates an output voltage higher than its input. In this application, the inductor in series with the load converts a collapsing magnetic field into a DC voltage higher than the input voltage of the circuit.
Another electrical energy conversion device is the buck-boost converter which can function as both a buck converter and a boost converter. In solar energy systems, a wide DC voltage range can be achieved depending on the availability of sunlight. A battery bank charged by a photovoltaic array can have a voltage between 40 and 56 VDC. If a sensitive load requires 47 to 49 VDC, a buck-boost converter will function as a boost converter when the battery bank voltage is below 47 V. The converter will function as a buck converter when the voltage is above 49 V.
Protect your devices with Threat Protection by NordVPN
