什么是耦合电感器:工作及其应用

电感器是双端电气分量,用于将能量存储在磁场内一旦电流通过它。它也称为扼流圈,线圈或反应器。通常,电感器包括绝缘线,其伤到线圈中。一对电感器is known as coupled inductors, which is used to transmit energy from one winding to another using the common core. So, this article discusses an overview of a耦合电感器and its differences from a transformer.


What is Coupled Inductor?

Coupled inductor definition是通过电磁感应可以通过电磁感应来完成两个线圈或电感的连接。每当在整个初级线圈的交流流动时,线圈将建立连接到次级线圈的磁场并引起线圈内的电压。从一个电感到另一个电感的诱导电压的现象称为相互电感。

Coupled inductors are mainly used as essential parts fortransformers,电子电路和配电系统。一对耦合电感器可以特征在于三个参数,如L1,L2和互感等两个自体电感,如L12 = M。这耦合电感符号如下所示。

Coupled Inductor Symbol
Coupled Inductor Symbol

耦合电感器方程

与其他电路相比,包括耦合电感器的电路更复杂,因为线圈的电压可以简单地以它们的电流简单地表达。

具有相互电感的耦合电感器
具有相互电感的耦合电感器

In the above-coupled inductor circuit, two coils like L1 & L2 are very close to each other. Because of the ‘i1’ current flowing throughout the primary coil ‘L1’, magnetic flux can be induced, and after that, it will be transferred to the secondary coil L2.

当“V1”电压施加到初级线圈'L1'时,'I1'电流将开始在整个线圈L1中流动。因此,当前变化率将产生通量在整个磁芯中供应,并在次级线圈'L2'内产生电压。

在初级线圈'L1中,'电流的变化率也改变了进一步控制次级线圈'L2'内的感应电压的磁通量。因此,可以通过使用以下公式来计算初级线圈'L1'内的感应电压。

PCBWay

V1 = M {di2(t)/dt}

From the above ‘V1’ equation, the mutual inductance ‘M’ is mainly responsible for the voltage which is induced mutually in two independent circuits. So, this mutual inductance (M) is the coefficient proportionality.

Similarly, for the first ‘L2’ coil, the mutually induced voltage because of mutual inductance for the ‘L2’ coil can be expressed as

v2 = m {di1(t)/ dt}

Similar to the inductance, mutual inductance (M) can also be measured in Henry. So, the highest mutual inductance value can be expressed as √L1L2. When the inductance induces voltage through the rate of change of current, mutual inductance (M) also induces a voltage which is known as mutual voltage M(di/dt). So, this mutual voltage is either positive (+ve) or negative (-ve) mainly depending on the construction of the inductor & the flow of current direction.

DOT公约

相互诱导的电压的极性可以通过像点约这样的基本工具来确定。在点转换中,“点”标记符号看起来像一个圆形,其主要用于两个线圈端在相互耦合的电路内。因此,该点符号提供关于其磁芯区域中的绕组结构的数据。

Dot Convention
Dot Convention

In the above dot convention circuit, the inductors L1 & L2 are mutually coupled. The V1 & V2 voltages are developed across the two L1 & L2 inductors which are the outcome of current flowing into the two inductors on the dotted terminals.

By assuming the two inductors mutual inductance is M, the voltage which is induced can be calculated by using the below formula,

For the primary inductor ‘L1’, the induced voltage ‘V1’ is;

V1 = L1(DI1 / DT)±M(DI2 / DT)

For the secondary inductor ‘L2’, the induced voltage ‘V2’ is;

V2 = L2(DI2 / DT)±M(DI1 / DT)

Thus, the above circuit contains two types of induced voltage like the voltage induced because of self-inductance & the voltage induced mutually because of the mutual inductance.

这voltage induced based on the self-inductance can be calculated with the formula like V = L(di/dt) which is positive (+ve), however, the voltage induced mutually can be negative (-ve) or positive(+ve) based on the construction of winding & the current flow. Here, the dot is an essential parameter used to determine mutually induced voltage polarity.

耦合电感分析和设计

通过使用以下反激式转换器电路可以进行耦合电感器的设计和分析。该电路可以用基本构建电子元器件like a coupled inductor (flyback transformer), a diode, the capacitor, etc.

Flyback Converter Circuit Diagram
Flyback Converter Circuit Diagram

这flyback converter circuit is apower supplytopology that uses a coupled inductor to store energy once current supplies throughout & the energy will be released once the power supply is detached. These converters are related to the booster converters in design & performance except the transformer’s primary winding can be replaced with an inductor whereas the secondary winding provides the o/p. Both the windings in the flyback arrangement are utilized as two separate inductors.

耦合电感器工作和操作

反激式逆变器电路如下所示。电路中的反激变压器是包括盖芯的耦合电感器。在整个循环中,一旦输入电压提供给变压器的初级绕组,能量可以存储在芯间隙内。之后,将能量转移到次级绕组以向负载提供能量。这些变压器主要用于反激式转换器,以提供电压和电路隔离的变换。

这principle of a flyback converter is, when the flow of current throughout an inductor is disabled, then the energy stored within the magnetic field can be released by reversing the terminal voltage suddenly.

这flyback diode in the circuit is connected across an inductor for eliminating flyback, which means when voltage surge was seen across the load once its current supply is interrupted or reduced suddenly. This diode is also known with different names like commutating diode, snubber diode, suppressor diode, freewheeling diode, catch diode, or clamp diode.

一般的ly, a switching device used in a flyback converter circuit is a MOSFET transistor which is switched ON & OFF by a PWM signal. The polarity of the transformer is generally upturned such that once the transistor is switched on, the flow of current will be there in the primary winding, but, the second diode is reverse biased so, there is no flow of current in this winding.

这energy will be stored within the transformer until the transistor is turned OFF. So, the energy which is stored will generate a current, so that the diode can be forward-biased which rectifies it to generate a DC output.

回程转换器用于电视机使用small amount of power, chargers of cell phones, computers, high-voltage supplies in CRT, Lasers, copiers, Xenon flashlights, etc.

耦合电感VS变压器

下面讨论耦合电感器和变压器之间的差异。

Coupled Inductor

变压器

这耦合电感器is mainly used for transmitting energy from the primary winding to the secondary through a core. A transformer is mainly used for power transmitting from the primary winding to the secondary.
Coupled inductor utilizes a gapped magnetic core for changing the voltage between two coils & transmits power at time intervals which are controlled. 这transformer utilizes a non-gap magnetic core for changing the voltage in between two coils & transmits the power in real-time.
这耦合电感器includes an air gap. 这transformer doesn’t include an air gap.
在耦合电感器中,输入功率不等于现有电源。 In a transformer, the entering power is equal to the existing power from the transformer.
这storage of energy in the core can be possible in the coupled inductor. 在变压器中无法在核心中存储能量。
It is used in DC to DC converter like flyback converter to decrease the voltage from 24V DC to 5V DC. 它用于AC到AC转换,如从120VAC-24Vac的交流壁出口的电压降低。

Advantages

advantages of a coupled inductorinclude the following.

  • Current ripple can be reduced significantly
  • Conversion of voltage.
  • Circuit impedance can be changed.
  • Galvanic isolation
  • Switching power supplies comprise multiphase converters, SEPIC converters, galvanically isolated converters & special converter circuits that decrease the hard switching negative characteristics.

Disadvantages

耦合电感器的缺点include the following.

  • Slightly higher losses
  • Non-ideal operations within the flyback converter
  • 这耦合电感器’s current specifications will change based on their windings which are connected within series or parallel.

Applications

耦合电感器的应用include the following.

  • Coupled inductors are used in electrical applications
  • Used in power conversion-based circuits like SEPIC, flyback, ZETA, Fly-Buck, Cuk & multi-phase topologies.
  • 这些电感器的性质将允许增加或减小电流和电压。
  • 这些用于在整个电路中传输阻抗
  • 这se can be used to isolate two circuits electrically from each other.
  • 这windings of the coupled inductor can be connected in different configurations for different purposes.
  • 这windings of these inductors can be connected separately to circuits to use like common mode chokes & isolation transformers.

Thus, this is all about an overview of the coupled inductor. A coupled电感用于DC到DC转换器for transferring one winding energy to another throughout the common core. These are existing in different sizes, current ratings, inductance values & shielded magnetically for low EMI (electromagnetic interference). The coupled inductor windings may have equivalent like 1:1 or un-equivalent turns ratios like 1:N. Here is a question for you, what is the function of an inductor?

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