Switching Power Supply: Design and Schematic
Design of a Switching Power Supply
"Welcome to the free information service over renewable energy and the market of the most reliable and efficient products for wind and solar photovoltaic systems!"
Finally SOLARIX has arrived, the Mppt Solar Charge Controller that is able to increase the energy efficiency of photovoltaic systems up to 30%!
With this program you will be able to size correctly the electric cables to connect battery and inverter of your photovoltaic system.
Easy and free!
Welcome in this information page of Mppt Solar. Perspective of saving energy and a cleaner and better future could not hold back from you know switching supply. In fact, this page will explain what a power supply switching, how it works, what is your wiring diagram, what are the differences between the old and the new linear regulated power supply and power differences between power switching type step-up (boost) and those of step-down (buck) and finally how to make a proper design.
Due to their small size and the possibility of obtaining a wide range of voltages, switching power supplies have now replaced the traditional linear power supplies in many applications. Many electronic hobbyists who would easily be able to build a regulated power supply linear, undergo many difficulties when they decide to build a switching power supply. If it is not difficult to understand in broad terms the principle of operation of this latest generation of power supplies, in fact, design one and make it work as it should, is another matter. Switching power supplies have, compared to a classic power supply, a schematic design decidedly more complex, not to mention that even in the stage of realization is indispensable to implement some design features.
Born from aerospace technology, which is of fundamental importance in the use of equipment of reduced weight and size, equipped with a high efficiency, the switching power supplies for several years now entered by force into common use, finding widespread in most electronic equipment.
It's due to their small size that it was possible to make devices more and more miniaturized and efficient, such as laptop computers, DVD players, mobile phone chargers, and many other devices of everyday use. The small size and light weight are not the only choice, because the offer to the electronic switching other possibilities, which make them almost irreplaceable in some applications. Just to mention one, that of being able to obtain an output voltage higher than that applied at input, the so-called step-up (or boost), that function can not be ensured by the classic linear power supply.
The latter in fact uses an adjustment element, generally constituted by a power transistor, on which it produces the voltage drop which adjusts the output voltage. In this case, the transistor works as a variable resistance placed in series with the load. It follows that the output voltage is always lower than the input.
It's a regulation system that works well, but has the disadvantage of a rather low efficiency, generally between a 30% and a 60%, since a non-negligible part of the power supplied input is dissipated and therefore lost on the element adjustment. The latter must be mounted on a suitable heat sink so that it works at temperatures not too much that many, not surprisingly, this power supply is also called "dissipative".
This does not happen with the switching power supply, which works in a completely different way. With this type of power supply is not only possible to produce output voltage values higher than those of input, but above all it reaches an efficiency much higher, of the order of 80% -90%, which makes it possible to to considerably reduce both the its size and those of the cooling fins and the power transformer and to extend the operating times of battery-powered equipment. As you are aware that this type of power can also be useful in small wind and photovoltaic plants where it is important to maximize the production and management of energy.
On the other hand, the switching power supply has some disadvantages, such as a ripple superimposed on the output voltage rather substantial and the presence of high frequency noise, which makes it inadvisable in certain sensitive applications, such as the stabilized power for laboratory or amplifiers hi -fi, in which the conventional power supply is still beneficial. To overcome the difficulty of designing the switching, are present time on the market numerous integrated circuits, hobbyists that offer the possibility of realizing each time the type of power supply which has necessity. One of these is the integrated MC34063A, which allows you to create a wide range of switching power supplies.
Switching Power Supply Design, 3rd Ed.
This Third Edition presents the basic principles of the most commonly used topologies, providing you with the essential information required to design cutting-edge power supplies.
Switching Power Supplies A - Z, Second Edition
This book provides you the theoretical and practical aspects of controlling and measuring Electromagnetic Interference in switching power supplies, including input filter instability considerations.
Switch-Mode Power Supplies Spice Simulations and Designs
Invaluable to both the graduating student and the experienced design engineer, this guide explains how to derive founding equations of the most popular converters.
Introduction to switching power supply step-down and step-up.
Below we will illustrate the two types of main power supply, and precisely the step-down, by which the DC output voltage is a value less than that applied in the input and the step-up, which allows to derive a DC output voltage exceeding that at input. We also explain what are the differences between these two configurations and how to calculate the various components needed to implement them. You will find so that with this integrated design of a switching is not difficult to become truly accessible to all. Once you are familiar with this area, you can enjoy meeting other switching power of a more complex and more sophisticated performance.
Switching power supply step-down.
The principle of operation of a switching power supply of the type step-down is represented in the figure beside. Input is applied the voltage coming from the rectifier assembly and leveler voltage, or from a battery. In this case, the switching power supply can also be seen as a DC-DC converter, ie direct voltage - direct voltage. On the input line is place a switch (S1), downstream of which is located an inductance L1 that is in series with the load, schemattizzato by the resistance RC. In parallel with the load is placed on capacitor C1. At one end of the inductance is connected to the cathode of the diode DS1.
To understand how the power supply must observe what happens in the closing phase and in the open position of the switch. Call Ton time in which the switch remains closed, the Toff time in which T remains open and the sum of the two times Ton + Toff. At the time of closure of the switch, begins to flow through it a current, which partly passes through the inductance and the load placed in series, and partly goes to charge the capacitor C1. The value of the current, flowing in the inductance, increases in a progressive manner during the time Ton, because this component has the characteristic to oppose the change of current running through it.
If the elapsed time Ton the switch is opened, the inductance will tend to circulate in the circuit the same current value that had been reached at that moment. At the terminals of the inductance produces a voltage in fact, with the polarity indicated the figure, which tends to circulate also for the time Toff the current on the load through the diode DS1, which is now forward biased. In this way the voltage across the load is also present in the time Toff, ie the switch is off. When the current through the inductance is reduced, which takes over the capacitor is discharged on the load, keeping the voltage constant. Attaching and detaching the switch periodically, is obtained in output a voltage whose amplitude depends on the ratio between the time Ton and the period T. This ratio is called duty cycle.
Switching power supply step-up.
With this type of converter is possible to withdraw an output voltage greater than that applied at input, provided that it is possible to obtain only with a switching power supply. In the figure beside we reported the basic schematic design of such a configuration. The inductance L1 with respect to the step-down configuration is placed in series, through the diode DS1, the input voltage and the output voltage.
During the phase Ton, when the transistor is saturated, the inductance stores energy to transfer it towards the outlet during the Toff phase, thus adding to the input voltage an additional voltage, which will produce an output voltage higher than the input . The diode DS1 prevents the output voltage to be shorted by the transistor during Ton.
Discover the wonderful advantages that solar and wind power makes us available:
1 free energy
2 clean and inexhaustible energy
3 energy accessible from all over the world
4 energy available at night through the ability to store it in batteries.
Was this information helpful? Keep up to date free of charge thanks to our Facebook Page!
How to properly connect in parallel equal and different panels, what happens in case of shading and how to optimize the system.
How to properly connect in series equal and different panels, what happens in case of shading and how to optimize the system.
Do you want to be updated on news from Mppt Solar? Subscribe: easy and free!
Want to learn more about Renewable Energy?
Well, in this section you will find some of the best books on the market, selected and ordered by Mppt Solar to provide a clear and comprehensive answers to your questions.