Have you ever wondered how high voltage is obtained in Hybrid Electric Vehicles and Lighting system? Also, there have been a lot of situations where we need a higher voltage than our power supplies can provide. We need 12 volts but have only a 9-volt battery. Or maybe we have a 3.3V supply when our chip needs 5V. Enter Boost Convertors.
It is a simple converter that is used to convert the DC voltage from a lower level to a higher level. Boost converters are also called a step-up converter due to its function. In this guide, we will see what is a Boost Converter, how it works, and the applications of it.Boost Converter
A boost converter (step-up converter) is a DC-to-DC power converter that steps up the voltage from its input (supply) to its output (load). It is a class of switched-mode power supply containing at least two semiconductors and at least one energy storage element: a capacitor, inductor, or the two in combination. To reduce voltage ripple, filters made of capacitors are normally added to such a converter's output and input.
Power for the boost converter can come from any suitable DC source, such as batteries, solar panels, rectifiers, and DC generators. A boost converter is a DC to DC converter with an output voltage greater than the source voltage. A boost converter is sometimes called a step-up converter since it "steps up" the source voltage.Working of Boost Converter
The main working principle of the boost converter is that the inductor in the input circuit resists sudden variations in input current. When the switch is OFF the inductor stores energy in the form of magnetic energy and discharges it when the switch is closed. The capacitor in the output circuit is assumed large enough that the time constant of the RC circuit in the output stage is high.
When the switch is closed, current flows through the inductor in the clockwise direction, and the inductor stores some energy by generating a magnetic field. The polarity of the left side of the inductor is positive.
(b) When the switch is opened, the current will be reduced as the impedance is higher. The magnetic field previously created will be destroyed to maintain the current towards the load. Thus the polarity will be reversed (meaning the left side of the inductor will become negative). As a result, two sources will be in series causing a higher voltage to charge the capacitor through the diode D.
While the switch is opened, the capacitor in parallel with the load is charged to this combined voltage. When the switch is then closed and the right-hand side is shorted out from the left-hand side, the capacitor is, therefore, able to provide the voltage and energy to the load. During this time, the blocking diode prevents the capacitor from discharging through the switch. The switch must of course be opened again fast enough to prevent the capacitor from discharging too much.
· In the On-state, the switch is closed, resulting in an increase in the inductor current;
· In the Off-state, the switch is open and the only path offered to inductor current is through the flyback diode, the capacitor, and the load. This results in transferring the energy accumulated during the On-state into the capacitor.
The input current is the same as the inductor current as can be seen in figure 2. So it is not discontinuous as in the buck converter and the requirements on the input filter are relaxed compared to a buck converter.
When a boost converter operates in continuous mode, the current through the inductor never falls to zero. In the steady-state, the DC voltage across the inductor must be zero so that after each cycle the inductor returns the same state because the voltage across the inductor is proportional to the rate of change of current through it.Applications of Boost Converter
- They are used in regulated DC power supplies.
- They are used in regenerative braking of DC motors
- Low power boost converters are used in portable device applications
- As switching regulator circuit in highly efficient white LED drives
- Boost converters are used in battery-powered applications where there is space constraint to stack more number of batteries in series to achieve higher voltages.
The NHW20 model Toyota Prius HEV uses a 500 V motor. Without a boost converter, the Prius would need nearly 417 cells to power the motor. However, a Prius actually uses only 168 cells and boosts the battery voltage from 202 V to 500 V. Boost converters also power devices at smaller-scale applications, such as portable lighting systems.
Given below is a list of some of the best Boost Converters at the best price that is used in various applications as mentioned above:-
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