Inductance is one of the essential components in electronic devices, and its role covers multiple fields from signal processing to power management. This article will analyze the working principle and practical application of inductance in detail from five aspects: the basic concept, characteristics, role, classification and key parameters of inductance.
I. Introduction to inductance
Inductance is a closed loop property based on electromagnetic induction. In a coil, when current passes through it, a magnetic field is generated around it; and the change of this magnetic field will generate an induced current in the inductor to offset the changing trend of the current. This phenomenon is called self-inductance. The unit of inductance is "Henry (H)", named after American physicist Joseph Henry. The size of the inductance value directly affects the performance of the inductor and is an important indicator to measure its self-induction ability.
II. Inductance characteristics
Inductance is a physical quantity that measures the ability of a coil to generate electromagnetic induction. When a non-steady-state current is passed through the coil, a changing magnetic field will be generated around it. The greater the power passed into the coil, the higher the intensity of the excited magnetic field, and vice versa.
III. The role of inductors in circuits
Basic roles: filtering, oscillation, delay, trapping, etc., can be summarized as: "passing DC and blocking AC".
- Passing DC: In a DC circuit, an inductor is equivalent to a section of wire, which has almost no impedance to the current.
- Blocking AC: In an AC circuit, the inductive reactance generated by the inductor increases with the increase of frequency, thereby hindering the transmission of AC signals.
IV. Classification of inductors
According to the structure and application scenarios, inductors can be divided into the following categories:
1. Color-coded inductors (color ring inductors)
- Mainly used in signal processing equipment.
- Due to low cost and easy identification, it is suitable for electronic products with low volume requirements, such as plug-in circuit boards.
2. Plug-in inductors
- I-shaped inductors: have lower DC resistance (RDC) and improve energy storage performance.
- Applied to signal and power circuits, but are more sensitive to electromagnetic interference (EMI).
3. Ring inductor
- Commonly used in power circuits, with good magnetic shielding, heat resistance and weldability.
- Widely used in high-frequency scenarios such as audio and video equipment, communication equipment.
4. Chip inductor
- Winding type: wide inductance range, high Q value, suitable for high-performance scenarios.
- Laminated type: miniaturized design, suitable for high-density installation.
- Film type: with higher precision and consistency, suitable for microelectronic devices.
- Braided type: used for anti-interference needs in special scenarios.
5. Magnetic beads
- Mainly used to absorb high-frequency noise.
- Unlike traditional inductors, magnetic beads are mainly used for energy loss and are used for EMI suppression and signal integrity control.
V. Interpretation of inductor parameters
When selecting and designing inductors, you need to pay attention to the following key parameters:
- Inductance
Inductance (self-inductance coefficient) is a physical quantity that represents the self-inductance ability of the inductor. Generally, the more turns a coil has, the denser the coil is, the higher the magnetic permeability is, and the greater the inductance is.
- Allowable deviation
The allowable error between the actual inductance of the inductor and the nominal value, expressed as a percentage.
- Quality factor (Q value)
The Q value is an important parameter for measuring the efficiency of an inductor, defined as the ratio of inductive reactance to equivalent loss resistance. The higher the Q value, the smaller the loss and the better the performance.
- Distributed capacitance
Distributed capacitance refers to the capacitance between turns of the coil and between the coil and the magnetic core. The smaller the distributed capacitance of the inductor, the better its stability.
- Rated current
The rated current is the maximum current value allowed to pass through the inductor when it is working normally. Exceeding this value may cause the inductor to overheat or be damaged.
Inductor identification method:
- Direct marking method: directly mark the inductance and allowable deviation on the outside of the inductor.
- Digital marking method: use three digits to represent the inductance value, the first two digits are valid digits, and the third digit is the number of subsequent "0".
- Text symbol method: Inductance and its deviation value are represented by a combination of letters and numbers. For example, "4R7" means 4.7μH, and "47N" means 47nH.
- Color code method: Similar to the color ring identification of resistors, colors are used to represent inductance values and errors.
Summary
Inductors play a vital role in modern electronic technology. From simple filtering functions to complex signal modulation applications, their design and parameter selection directly affect the performance of the circuit. A deep understanding of the characteristics and applications of inductors can help engineers achieve more efficient and stable circuit solutions in their designs.
