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All colleagues unite and focus their efforts to write a new chapter of developmentWhat are the operating modes of a switching power supply, and what are their characteristics?
所属分类： Industry News
发布时间：2020-04-16
As the name suggests, Switching power supply It employs electronic switching devices—such as transistors, field-effect transistors, and thyristors—and, through a control circuit, repeatedly switches these devices between “on” and “off” states. This enables pulse‑width modulation of the input voltage, thereby achieving DC/AC and DC/DC voltage conversion, as well as adjustable output voltage and automatic voltage regulation.
Work mode
Switching power supplies typically operate in three modes: frequency‑fixed, pulse‑width‑fixed; frequency‑fixed, pulse‑width‑variable; and both frequency and pulse width are variable. The first mode is commonly used in DC/AC inverters or DC/DC voltage converters, while the latter two are predominantly employed in switching regulators. In addition, switch-mode power supplies offer three methods for regulating output voltage: direct‑output voltage control, average‑value output voltage control, and peak‑value output voltage control. Again, the first method is often found in DC/AC inverters or DC/DC converters, whereas the second and third methods are more typical of switching regulators.
Based on the way switching devices are connected in the circuit, switch-mode power supplies can generally be classified into three major types: series‑type, parallel‑type, and transformer‑type. Among these, the transformer‑type switch-mode power supply (hereafter referred to as the transformer‑type SMPS) can be further subdivided into push‑pull, half‑bridge, full‑bridge, and other configurations. Depending on the transformer’s excitation scheme and the phase relationship of the output voltage, it can also be categorized into forward, flyback, single‑ended, and dual‑ended topologies. Moreover, when classified according to their applications, even more distinct types can be identified.
Key Features
1. Compact size and lightweight: Without a mains-frequency transformer, its volume and weight are only 20–30% of those of a linear power supply.
2. Low power consumption and high efficiency: Power transistors operate in switching mode, resulting in low power dissipation and high conversion efficiency—typically 60–70%—whereas linear power supplies achieve only 30–40%.