Inductance is the phenomenon that a conductor resists changes in the current flowing through it. The essence of inductance lies in Maxwell's equations concerning the change of magnetic field and electric field. When the current in a conductor changes, the corresponding magnetic field also changes. According to Faraday's law of electromagnetic induction and Lenz's law, this generates a corresponding electromotive force (EMF), which resists the change in current. Inductance is defined as the ratio of the induced voltage to the rate of change of the current that causes the induced voltage. The dimension of inductance is ML²Tˉ²Iˉ², and the unit in the International System of Units (SI) is H (henry). 1H of inductance represents the inductance that causes a voltage change of one volt when the current changes at a rate of one ampere per second. Electromagnetic induction phenomenon.
The working principle of an inductor is based on the phenomenon of electromagnetic induction. When current flows through an inductor coil, a magnetic field is generated. When the current changes, the magnetic field also changes; this phenomenon is called self-induction. Self-induction generates an induced electromotive force (EMF), the direction of which always opposes the change in the current that caused the self-induction. Specifically, when the alternating current increases, the direction of the self-induced current is opposite to the direction of the alternating current; when the alternating current decreases, the direction of the self-induced current is the same as the direction of the alternating current. This characteristic makes the inductor have a blocking effect on alternating current. 1. Definition and Characteristics of Inductance
Inductance is the phenomenon that a conductor resists changes in the current flowing through it; its essence lies in the change in the electric field caused by a change in the magnetic field, as described in Maxwell's equations. Inductance is defined as the ratio of the induced voltage to the rate of change of the current that causes the induced voltage; its unit in the International System of Units (SI) is the henry (H). In a circuit, inductance acts as a short circuit for direct current (DC), but it impedes alternating current (AC), and the higher the frequency of the AC, the greater the impeding effect of the inductance.
Applications of inductors
Inductors have a wide range of applications in electronic circuits, for example:
Transformer: A transformer uses the principle of mutual inductance to transfer voltage from one circuit to another.
Low-pass filter: A low-pass filter uses the impedance of an inductor to allow low-frequency signals to pass through while blocking high-frequency signals.
Electric motors and generators: These devices use the principle of electromagnetic induction to convert electrical energy into mechanical energy or vice versa.
The physical basis of inductance
The physical basis of inductance is Faraday's law of electromagnetic induction and Lenz's law. When the current changes, the induced magnetic field also changes, thus generating an induced current. This induced current is in the opposite direction to the original current, thereby creating a resistance effect.
inductance
Inductance is a property of a closed circuit, meaning that when the current through the closed circuit changes, an electromotive force (EMF) will appear to resist the change in current. It is short for 'electromagnetic induction'.
Inductor:
An inductor is a circuit component that generates an electromotive force (EMF) in response to changes in the current flowing through it, thereby resisting those changes. The term "inductor" is generally used only to refer to devices whose primary function is self-induction or its effect. Devices that do not primarily rely on self-induction are usually referred to by other names and are not commonly called inductors; examples include transformers and the windings of electromagnetic coils in motors.
Working principle of inductor
When an alternating current is applied to an inductor, the change in its own current causes a change in its own magnetic flux, which in turn induces an electromotive force. This phenomenon is called self-induction. The direction of the self-induced current always opposes the change in the current that causes the self-induction. When the alternating current increases, the self-induced current is in the opposite direction to the alternating current. When the alternating current decreases, the self-induced current is in the same direction as the alternating current. In this way, it has a blocking effect on the alternating current.
1. Self-perception
When current flows through a coil, a magnetic field is generated around the coil. When the current in the coil changes, the surrounding magnetic field also changes accordingly. This changing magnetic field induces an electromotive force (EMF) within the coil itself (EMF is used to represent the terminal voltage of an ideal power source for an active component).
2. Mutual inductance
When two inductors are brought close together, the change in the magnetic field of one inductor will affect the other inductor; this effect is called mutual inductance. The magnitude of mutual inductance depends on the self-inductance of the inductors and the degree of coupling between the two inductors. A component made using this principle is called a mutual inductor.
Inductance
The rate of change of voltage and current in an inductor is directly proportional. This relates to the relationship between voltage and current.
The proportional constant L is the inductance coefficient, which is related to the physical parameters of the inductor, such as the shape of the coil, the number of turns, and the core structure.
The unit of inductance is the Henry, abbreviated as H. 1H is the inductance corresponding to an induced voltage of 1V when the current changes by 1A/s.
The function of inductor
Traffic obstruction
For direct current, inductance is equivalent to a short circuit; while for alternating current, inductance impedes it, and the higher the frequency of the alternating current, the greater the impediment effect of the inductance.
transformer
The most commonly used inductor is the transformer. Figure 1 shows the circuit symbol of a transformer. If the number of turns in the left coil is 100 and the number of turns in the right coil is 50, and if the left coil is connected to 220V AC, then the voltage induced on the right coil will be 110V, that is, "turns ratio = voltage ratio", but the current will be completely opposite; if 1A of current flows into the left coil, then 2A of current will flow out of the right coil, that is, "turns ratio = inverse ratio of current", because inductors only change voltage and current, but cannot change power. It would be illogical for voltage and current to be directly proportional.
I. Working principle of inductors
An inductor is a component that stores magnetic field energy. In circuits, it primarily functions as a filter, oscillator, delayer, and notch filter. Its working principle is based on the law of electromagnetic induction: when the current in a conductor coil changes, it generates a changing magnetic field. This magnetic field induces an electromotive force in the conductor coil, opposing the change in current. Inductors utilize this effect to store and release magnetic field energy.
The main parameters of an inductor include inductance, quality factor (Q value), and self-resonant frequency. Inductance determines the inductor's ability to store magnetic field energy, the quality factor reflects the inductor's performance at the resonant frequency, and the self-resonant frequency is a key indicator of the inductor's performance degradation at high frequencies.
II. Classification of Inductors
Inductors can be classified into various types based on their structure and operating characteristics. Here are some common classification methods:
Inductors can be classified into two types based on their inductance type: fixed inductors and variable inductors. Fixed inductors have a fixed inductance, while variable inductors can have their inductance changed mechanically or electromagnetically.
Inductors can be classified according to the nature of their magnetic conductor: air-core coils, ferrite coils, copper-core coils, aluminum-core coils, etc. The main difference between these inductors lies in the material of their magnetic conductor, which directly affects the inductor's performance.
Inductors can be classified according to their function: antenna coils, oscillator coils, choke coils, filter coils, coupling coils, and choke coils. These inductors play different roles in circuits to meet different application requirements.
III. Applications of Inductors
Circuit tuning: Inductors are used as tuning elements in circuits, such as in the tuning coil of a radio and the resonant coil of an intermediate frequency transformer.
Oscillating circuits: Inductors are also used in oscillating circuits, such as the oscillating coil in a radio and the inductor coil in various LC oscillating circuits.
Current filter: Inductors are commonly used in LC filter in power supply filters to filter out noise, spurious signals and other harmful signals in the circuit, ensuring the reliability of the circuit operation.
Frequency selection: Bandpass and bandstop filters use resonant inductors for frequency selection. Inductors are also used to select signals of specific frequencies, which is especially common in wireless communication, modulation and demodulation, audio and other fields.
Energy storage: Inductors can store electrical energy and release it when needed, and are used in circuits for instantaneous power compensation, switching power supplies, amplifiers, etc.
Control, Detection, and Protection: Inductors can measure the strength and direction of electromagnetic fields, thereby controlling the operating status of electronic equipment, such as controlling the speed and direction of motors, and controlling the switching and adjustment of circuits. Simultaneously, they can detect and measure changes in electromagnetic fields and events that occur, protecting electronic equipment from damage caused by electromagnetic waves.
IV. Introduction to Popular Models
With the continuous development of electronic technology, the types and models of inductors are also constantly being updated. Below are some currently popular inductor models:
CD32 inductors are a common and best-selling power inductor model on the market. They typically measure 3mm x 3.2mm x 2.5mm and are characterized by miniaturization, high quality, high energy storage, and low resistance. CD32 inductors are widely used in computer graphics cards, pulse memory circuits, and DC-DC converters. Due to their unique construction and coil technology, they achieve low DC impedance and high current tolerance.
CKO32 inductors are typically used in power supply circuits requiring high power output and small size. These inductors play a crucial role in circuit design, ensuring power supply stability and efficiency. Their specific dimensions and performance parameters may vary depending on the manufacturer and application.
0402 inductor: This is a surface-mount device package with dimensions of 0.4mm x 0.2mm. This miniaturized inductor is widely used in electronic products such as mobile phones and tablets. It features a flexible lead design to ensure proper component positioning and good mechanical reliability. The 0402 inductor meets the requirements of high-frequency circuits and functions as a current limiter, voltage reducer, and voltage divider.
0503 Inductor: This may be an inductor model designation specific to a particular manufacturer or application area. Since specific product information and performance parameters may vary between manufacturers, it is recommended to consult the relevant manufacturer's technical documentation or contact the manufacturer directly for accurate information.
