Push & Pull Converter

 Push & Pull Converter 

One of the earliest switching topologies, the push-pull converter may produce several outputs from a single input. It is also one of the most commonly used in industries. By altering the turns ratio of the transformer's windings, it is possible to make the output voltages of the device lower or higher than the input voltages.

When dealing with power electronics, a DC-DC converter topology becomes very important for the practical designs of devices. Switching converters and linear converters are the two primary topologies that may be used for large DC-DC conversions in power electronics. Both of these topologies have their advantages and disadvantages. The rule of conservation of energy states that energy cannot be generated nor destroyed, but the only thing that can happen to energy is for it to be converted. The same is true for switching regulators. The wattage, or output power, of any converter, is equal to the product of its output voltage and current. In an ideal situation, a DC-DC converter will convert either the voltage or the current while maintaining the same wattage.

Push-pull Converters may be identified by their defining characteristic of pairs of transistors in a symmetrical push-pull circuit. These transistors, which regularly turn on and off units, reverse the current flowing through the transformers. As a result, there is a draw on the line's current supply during both halves of the switching period. The distinction between buck-boost converters and push-pull converters is that the former utilizes a single transistor in the same manner as the latter, but draws current for only one-half of the time. Therefore, thanks to this particular push-pull circuit, push-pull converters have a stable input current, generate less noise on the input line, and are more efficient in applications that need more power. The simplest push and pull converter generally consists of transistors that can be used as switches, center-tapped transformers, and Diodes that work as rectifiers and LC filters. 

Initially in the first half cycle of the switching frequency, the Supply will be turned on for the first switch and the other switch will be turned off. The current will flow in a clockwise direction, and Diode 1 will become forward biassed while Diode 2 will become reverse biassed. The ripple in the output voltage will be smoothed down by an LC filter, resulting in a pure DC version of the output voltage. In the second half cycle, the reverse process occurs. 

So that the output voltage may be controlled and maintained over a wide range of time intervals, by using two transistors as switches. But the most crucial rule is that two transistors cannot be closed at the same time since this might result in damage. Middle to high power (150W to 1000W) applications often adopt push-pull designs, which operate more efficiently and produce less noise.

               Typical Push And Pull Converter

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