# 什么是RL电路：工作和其用途

The resistor (R), inductor (L), and capacitor(C) are the basic passive linear circuit elements. These components play a key role to form an electrical circuit in four different ways like the RL circuit, theLC电路和RLC电路。这些电路在模拟电子器件中是必不可少的，因为它们表现出大腿性能。必威网址下载一般来说，两者都是capacitorsand inductors are more preferred as compared with other basic components because the manufacturing of these can be done very easily. These elements are small in size for mostly high values of components. A single-pole filter can be formed by using both the RL and RC circuits. When the reactive elements like capacitor or inductor are connected in series/parallel with the load so that it will state whether the filter is high-pass or low-pass. The RL circuits are frequently used in RF amplifiers like DC power supplies, wherever the inductor (L) is used to supply DC bias current & block the RF from reaches back into the power supply.

## 什么是rl电路？

An RL circuit is also known as an RL filter, resistor–inductor circuit otherwise RL network, and it can be defined as a circuit that can be built with passive circuit components like resistor and inductor through a current source or voltage source. Because of the existence of a resistor R in the perfect form of the circuit, this circuit will utilize energy similar to an RC/RLC circuit.

这不像LC电路的完美形式，由于电阻不存在，这将没有能量。即使，这只是在电路的完美形式。实际上，即使是电感电容器电路也将使用一些能量，因为不存在电阻和连接线。

Consider the following RL circuit which includes a resistor and inductor using a voltage supply. Let us believe the flow of current within the circuit is I (amp) & through the resistor is IR & the inductor is IL correspondingly.

由于R＆L等组件串联连接，因此组件和整个电路中的电流流量将与IR = IL = I相同。电阻器和电感器上的电压降是VR＆VI

ApplyingKirchhoff电压法(i.e sum of voltage drop must be equal to apply voltage) to this circuit we get,

Once KVL (Kirchhoff voltage law) is applied to the above circuit, then we get

**V = V _{R}+V_{L}**

### 功率因数

The RL circuit or resistor-inductor circuit is one kind of electric circuit that can be built with resistors & inductors which are connected to a voltage or current source. A first-order RL circuit mainly comprises one resistor & one inductor to form an RL circuit. Thepower factorof this circuit is low because of the inductive load like a 3-phase induction motor. Even the lamps, transformers, welding devices operate at low lagging power factors.

In the RL series circuit, the flow of current is lagging behind the voltage through an angle ‘ϕ’ due to the inductor effect. So here, the power factor (PF) can be given like the cosine of lagging angle ‘ϕ’

The power factor = Cos ϕ = Resistance/Impedance = R/Z

**cosφ= r /√r ^{2}+X_{L}^{2}= R/√R^{2}+ (ω_{L})^{2}**

The above equation can be divided with ‘R’

**Cosφ= 1 /√1+（ω _{L /}R)^{2}**

实际上，当我们有ωl>> r时，即小功率因数，分母中的“1”变得微不足道。

**所以，Cosφ= r /ωl**

### Phasor Diagram

The**phasor diagram of the RL Series circuit**is shown below:

以下步骤逐步提供指令绘制Phasor图。

这里，电流（i）可以作为参考。

The VR which is known as the voltage drop across the resistance = IR can be drawn within phase through the current (I).

在感应电抗的横跨电压下降是VL = IXL可以在电流的流程之前绘制，因为，电流的流动通过电感电路内的90度延迟电压。

The two voltages vector sum drops are VR & VL which are equivalent to the given voltage V.

所以，

在上面的三角形，如oab

**V _{R}= I._{R}and V_{L}= I.X_{L}其中x_{L}=2πflrl.**

**V = √(V _{R})^{2}+（V._{L})^{2}**

^{=}√(I_{R})^{2}+ (IX_{L})^{2}

**=I√® ^{2}+（X._{L})^{2}**

**I = L = V/Z**

**z =√r. ^{2}+ X_{L}^{2}**

Here, ‘Z’ is the whole resistance that is offered to the flow of AC through an RL Series circuit. So it is known as the impedance of the RL circuit and it is measured in ohms (Ω).

#### 相位角

在RL串联电路中,流of current lags the voltage with 90o angle is called as phase angle

**φ= TAN.-1 (X _{L}/R)**

#### The Impedance of Series RL Circuit

The series RL circuit’s impedance opposes the current flow and it is nothing but the combination of resistance (R) & inductive reactance (XL) effect of the entire circuit. The impedance ‘Z’ within ohms can be given like the following.

**Z = (R ^{2}+ XL.^{2）0.5}**

从以下图像中的直角三角形，相位角**φ= TAN. ^{-1}（X_{L}/R).**

### RL并联电路

When both the resistor as well as the inductor is connected in parallel connection through each other and supplied through a voltage source is known as RL parallel circuit. The circuit’s input and output voltages are Vin and Vout. Once the resistor & inductor are connected within parallel then the Vin is equivalent to Vout. However, the flow of current within these components is not the same.

这种电路不能用作电压的滤波器，因为该电路中的输入和输出电压都是相等的。因此，由于这个原因，该电路不经常使用为串联RL电路。

#### Phasor Diagram

在一个平行的RC电路,主要的关系ong the voltage ¤ts can be illustrated through the vector (phasor) diagram.

- 参考矢量'E'并表示RL并联电路内的电压。
- As the flow of current throughout the resistor is within phase by the voltage across it, then IR is shown on the voltage vector.
- The ‘IL’ lags the voltage through 90 degrees angle & can be arranged within a down direction for lagging the voltage vector through 90 degrees angle.
- Here, both the vectors addition like IR & IL provides a result that signifies the sum (IT) otherwise line current
- The angle ‘θ’ denotes the phase among the given line current & voltage.
- 并行RL电路相位图如下所示。

In the case of a parallel circuit, the flow of current within every branch of a circuit performs independently of the currents within the remaining branches. The flow of current in every branch can be determined through the voltage across the branch & the resistance to flow of current in the form of either inductive reactance or resistance included within the branch.

单个分支中的电流可以通过欧姆法确定

**I _{R}= E/R**

**I _{L}= E/X_{L}**

电阻分支内的电流流包括给定电压的类似相;然而，电感分支中的电流滞后于具有90度的给定电压。因此，整个线电流包括IR和IL，彼此通过90度。

The flow of current in both the components can form the legs for a right triangle & the whole current is the hypotenuse. So, the Pythagorean theorem is used to include these currents together through using the following equation:

**I _{T}= √I_{R}^{2}+ I_{L}^{2}**

In these circuits, the phase angle by which the whole current lags the voltage is anywhere between 0 & 90 degrees. So, the angle size can be determined through whether there is an additional inductive current otherwise resistive current.

如果存在额外的电感电流，则相位角度'θ'将更靠近90度。如果存在额外的电阻电流，它将更接近零度。因此，从上面的电路矢量图，我们可以观察到相位角值可以从以下等式测量：

**θ= tan-1（i _{L}/I_{R})**

#### Impedance

The impedance of a parallel RL circuit can be defined as the whole resistance toward the current flow. It comprises the resistance that is offered from the resistive ‘R’ branch as well as the inductive reactance ‘XL’ can be offered through the inductive branch.

The parallel RL circuit’s impedance can be calculated like a parallel resistive circuit. But, since R & XL are vector quantities, so they should be included vectorially. Consequently, the impedance equation of a parallel RL circuit includes a single resistor & inductor, So the impedance formula for a parallel RL circuit is

**Z = RX _{L}/√R^{2}+ XL.^{2}**

在上述等式的分母中是电阻和电感电阻的矢量和。因此，如果电阻和电感的一个分支，则它们必须相当于这些平行分支的整体阻力。

一旦整个电流和施加的电压是众所周知的，就可以通过使用如下方式使用欧姆的法律更简单地测量阻抗。

**Z = E/I _{T}**

The parallel RL circuit’s impedance is low always as compared to the resistance otherwise inductive reactance of any branch. Due to this is the reason, every branch forms a separate lane for the flow of current, therefore decreasing the whole circuit resistance toward the flow of current.

When the branch has the highest amount of current so that has the most effect on the phase angle. So, this is reverse to a series RL circuit.

在并联RL电路中，如果电感高于电阻，则与电感分支电流相比，电阻分支电流优越。因此，给定电压和整个电流之间的相位角可以更靠近0度，因为它在性质中更响应。

### RL电路使用

组合电阻器，电容器和电感器等基本组件以形成不同的电路，例如RC，RL和RLC电路。RL电路的应用，RC＆RLC包括以下内容。

- RF Amplifiers
- Communication Systems
- Filtering Circuits
- Processing of Signal
- Oscillator Circuits
- 电流或电压的放大率
- Variable Tunes Circuits
- Radio Wave Transmitters
- Resonant LC Circuit/RLC Circuit
- These circuits are used as DC power supplies within RF amplifiers because the inductor (L) is used to supply DC bias current & block the RF to reach the power supply.

因此，这一切都是关于an overview of RL Circuit, RL series circuit, RL parallel circuit, phasor diagram, and its uses. Here is a question for you, what are the advantages of RL circuits?