Introduction to the role and common applications of magnetic ring inductance
Inductor is one of the commonly used components in circuit design. It can form LC filter network with capacitor C, form freewheeling function with diode in step-down circuit, and can also be used in LC resonant circuit. Common applications of inductors are described below. 1. Use capacitors to form a liquid crystal filter circuit As we all know, inductance can pass DC and resist AC, because the inductance of the inductor has a great relationship with the AC frequency. The higher the frequency, the greater the inductance. As shown in the figure below, it is the most commonly used circuit structure of switching power supply, and the inductor and capacitor play the role of filtering. The AC ripple in the circuit will be filtered by the inductor and the capacitor C to make the back-end output smoother. This is typically used in switching power supplies or high power applications.
2. Used in DC/DC step-down circuit The DC/DC step-down chip has a wide input range and high conversion efficiency. The circuit principle of the DC/DC step-down chip is generally realized by inductors, capacitors and diodes. As shown in the figure below, it is an ordinary DC/DC power chip, in which the inductor and diode constitute the freewheeling function. When the internal MOS tube is turned on, the inductor stores energy; when the internal MOS tube is turned off, the inductor can supply power to the load. This is also the most commonly used PWM step-down principle.
3. Used in LC resonant circuit LC can form series resonance or parallel resonance, also called frequency selection, that is, among many input frequencies, only those that are consistent with the resonant frequency can pass. This circuit is commonly used in broadcast, television and other applications. When designing an LC resonant circuit, extensive calculations are required to determine the optimal parameters for inductance and capacitance.
A toroidal inductor is a coil with a magnetic toroid. Because the coil has inductive reactance to alternating current after it is energized, it constitutes an electronic component - an inductance! Its inductance value ranges from zero to ten millitin. Originally, only the coil can form the inductance, but in order to increase the inductance, reduce the volume and DC resistance of the wire, and increase the ferrite core with the smallest eddy current loss. For example, if a magnetic core with a permeability of 100 is added to a coil of 1 microenjoy, the theoretical inductance increases by a factor of 100, becoming 100 microenjoy. But the actual increase is not only the permeability, but also the shape of the magnetic core (in addition to the ring, there are also cylindrical, square, bar, king, mouth, etc.). High-frequency AC circuits generally use tens of milliseconds or less. the core inductance. AC circuit inductances above a few hundred milliseconds below a few hundred hertz - enjoy. Not suitable for magnetic cores, use microcrystalline, slope film alloys, or even silicon steel sheets! The volume and weight are much larger! Do not add iron cores where the inductance quality is extremely high.
Inductive components are mainly used in resonant circuits, bandpass filters and bandstop filters. According to the design requirements, the circuit consists of a tuning circuit, a frequency selector, a wave trap, a filter, a high frequency and an intermediate frequency transformer, an anti-interference circuit, a damping circuit, a spark suppression circuit, an energy storage circuit, and a bridge. Commonly used for filtering and anti-interference!