【Simulation Model】03-Inductor

1. Basics of Inductors

        An inductor is formed by winding a wire into a coil. Inductors have the property of hindering current changes. For convenience, the inductor can also be referred to as an inductor, and the unit of inductance is H (Henry). Although inductors are composed of coils, they can basically be divided into two categories, fixed inductors and variable inductors. They are mainly divided into the following categories according to different processes and packaging:

(1) SMD inductors: This type of inductors can be divided into low-power and high-power inductors, which can be distinguished by their size. The ones that are small in size and the size of patch capacitors are low-power inductors, and the ones that are large in size are high-power inductors.

(2) Color ring inductor: It looks like a color ring resistor. It is generally green in appearance and the reading method is the same.

(3) Power inductor: This type of inductor is often used in circuits with higher power. It can also be subdivided into magnetic core inductors composed of coils and magnetic cores and coils simply wound with thicker enameled wires;

(4) I-shaped inductor: This type of resistor has a more complex structure and is larger in size, so it can carry larger currents. It is named after its special shape;

(5) Common mode inductor: This type of inductor is often used for anti-interference capability in switching power supplies, UPS and other power equipment. The structure is a closed magnetic ring with coils wound symmetrically in opposite directions. It can be manually performed according to different application scenarios. Winding.

(6) Variable inductance: By adjusting the position of the magnetic core in the coil, it changes the inductance.

        Inductors are not as widely used as capacitors. They are mainly used for the anti-interference ability of circuits, providing noise suppression and tuning functions. For example, in a switching circuit, high-frequency noise will be generated due to the presence of some high-frequency components. Since the inductive reactance of the inductor increases as the frequency increases, the high-frequency noise can be well suppressed.

2. Inductor simulation demonstration

        Lichuang EDA provides basic inductor device simulation, including American standards, European standards and 3D style drawings. It can be used during actual simulation.

        The basic function of an inductor is to generate voltage to hinder current changes, but the current in the inductor cannot change instantaneously. Analogous to the charging and discharging of a capacitor, a time constant τ (τ=L/R) is also taken here. It also passes through 5 time constants, that is, 5τ After the current becomes stable, you can use simulation tools to verify:

        Open EasyEDA and switch to simulation mode. Call a resistor and inductor from the simulation base library, a pulse source from a voltage source. There are currently no current probes. We can also use voltage probes to detect changes in current. Place a voltage probe at both ends of the resistor, named V1 and V2 respectively. Draw according to the following circuit device parameters and wiring:

        Among them, the pulse voltage source can be selected from the voltage source, and the parameter settings are as follows:

        After checking that the circuit is correct, click Run Simulation (shortcut key F8) to get the following simulation results. From the time constant calculation formula, we can see that τ=L/R=1/1K=0.001s=1ms, 5 times the time constant is 5ms. From the figure, we can see that the orange line V1 is the waveform diagram of the pulse voltage source, with a period of 20ms; blue The color line is V2, which represents the voltage change of the inductor. When the power is turned on, due to the characteristics of the inductor that blocks the current, the voltage across the inductor decreases. After 5ms, the voltage across the inductor is 0. At this time, the inductor is short-circuited. The current tends to be stable; when the voltage suddenly drops from a high level to a low level, the voltage change causes the inductor to generate an induced voltage that hinders the reduction of the current. The reverse voltage generated at this time slowly decreases with time, and after reaching 5ms, it is close to 0, the current is stable at 0 at this time.

        In practical applications, the inductance parameters are small and the response speed is fast. After fully understanding the characteristics of the inductor, you can deepen your understanding of the working characteristics of the circuit. In the subsequent simulation demonstration, we will show you more application cases of the inductor. Welcome everyone to continue to pay attention to Lichuang EDA simulation teaching class.

Click to view the video explanation: https://www.bilibili.com/video/BV1Ab4y1a7hg