I've never heard of it as "soft commutation" just because of the diode. The anti-parallel diode is used in a lot converters with "soft commutation" though. That's largely because the schottky diode is often a better diode than the FET's body diode. Some type of diode is needed, body or anti-parallel, to implement deadtime which ensures both switches aren't on at the same time during commutation. The external diode is a way to reduce dead time losses.Baluncore said:I believe a simple flyback diode would be classed as “soft commutation”. If you parallel the flyback diode with a MOSFET you can improve efficiency by reducing the flyback diode voltage drop. The gate of the parallel MOSFET would need a control signal from somewhere, and could then be called “synchronous rectification” or even “hard commutation” because it is forced.
4.1 INTRODUCTION
In the Chapter 3, it has been shown that AC supply of inductive or capacitive loads can be achieved very satisfactorily (high efficiency, low distortion). It has also been shown that the performance of these resonant inverters was tightly linked to the commutation process in these switching devices all of which execute one controlled switching and one inherent switching.
We will define as a soft-commutated direct converter a converter only involving switches, each of these switches having at most one controlled switching and at least one inherent switching, the controlled and inherent switchings being if necessary different from one switch to another. So the soft commutation is not compatible with totally controlled switches. In soft-commutated converters the power transfer is controlled by means of switches or by a set of switches with thyristor or dual thyristor switching features.
The term 'soft commutation' is legitimate since those switches that have one controlled switching and one inherent switching can be fitted with lossless snubbers (a series inductor when turn on is controlled or a parallel capacitor when turn off is controlled) so that the switching losses are considerably reduced.
A synchronous buck converter switching is a type of DC-DC converter that uses two power switches (usually MOSFETs) to regulate the output voltage. It operates by switching the input voltage on and off at a high frequency, and then stepping down the voltage using an inductor and capacitor.
Compared to other types of DC-DC converters, synchronous buck converters have higher efficiency and better regulation of the output voltage. They also have a smaller size and lower cost due to the use of fewer components.
The main components of a synchronous buck converter switching are the two power switches (usually MOSFETs), an inductor, a capacitor, and a control circuit. The control circuit is responsible for regulating the switching of the power switches to maintain a stable output voltage.
The main difference between a synchronous and an asynchronous buck converter is the use of a diode in the latter. In an asynchronous buck converter, the diode is used to rectify the output voltage, while in a synchronous buck converter, the second power switch is used instead of a diode. This results in higher efficiency and better regulation in synchronous buck converters.
The efficiency of a synchronous buck converter switching is calculated by dividing the output power by the input power. It is affected by various factors such as the switching frequency, the characteristics of the components used, and the load conditions. Generally, synchronous buck converters have efficiencies ranging from 80% to 95%.