How to correctly understand the principle that the current of the inductor cannot be abrupt and the

This problem of inductance has also puzzled me for some years, but in retrospect the painstaking process of understanding it has strengthened my conviction: all science has its logic, and I firmly believe that this logic can be understood by the human brain, provided that the problem is viewed objectively enough and there is no problem that cannot be understood. Okay, let's get down to business:

The principle of capacitance please refer to ZYJ1953414 and will not repeat it, here I will add the question about inductance, which involves a feedback structure, to understand it, we must first establish a thinking model of a feedback loop in our minds.

When a voltage U is applied to an inductor, the current i in the inductor must undergo a change process from 0 to U R (R is the internal resistance of the U voltage source plus the internal resistance of the inductor itself), and the change process of this current increase will produce a weak and strong magnetic field around the inductor, and this changed magnetic field will cause the inductor to induce a voltage ug, the direction of the UG voltage is opposite to the direction of u, and the effective voltage that can produce the current is equal to u minus ug, which constitutes a feedback loop: if Once the induced voltage increases, the u-ug will decrease, and the current will slow down, and finally the current in the inductor will increase in equilibrium. Therefore, due to the obstacle of the induced voltage, the increase of the current cannot be completed instantaneously, that is, it cannot be abruptly changed, and in the same way, when the current decreases, the direction of ug is the same direction as you, and the effective voltage of the generated current is equal to u+ug, and the analysis process is the same as above.

Here I want to explain the problem of inductor reverse peak voltage: suppose a current of 1A is flowing through an inductor, and suddenly a switch turns off this current, at this time, if the inductor does not have any devices connected in parallel and the speed of this shutdown is infinitely close to 0 seconds, then the change speed of this current 1a 0s is infinite, the current change speed is infinite, the magnetic field change speed will also be infinite, and then an infinite induced voltage will be generated, that is, the inverse peak high voltage of the inductor.

In this case, if a device is connected in parallel at both ends of the inductor so that the reverse peak voltage can form a current in the inductor, then the feedback loop described above will be formed, and the voltage will no longer be infinite. That's why we add freewheeling diodes to our inductor circuits.

One explanation: When the inductor coil is turned on with voltage, a back-EMF equal to the applied voltage is instantaneously generated, blocking the flow of current.

Two explanations: the magnetic field formed by the inductance coil always has to maintain the current in the coil.

It is easy to understand that the voltage of the capacitor cannot be abruptly changed: because the voltage at both ends of the capacitor is formed by the accumulation of charges on the two plates, the accumulation of charges cannot be completed instantaneously, and a charging process is required.

The inductance is like a waterwheel, when the water comes, it can't reach its maximum speed all at once, so you have to slow it down! Capacitors need to be charged, and charging takes time. The same cannot be mutated!!

The reason why the voltage at the capacitor terminal and the current of the inductor cannot be abruptly changed is ().

a.The rates of change of electric field energy and magnetic field energy are both finite values.

b.The terminal voltage and current of the same element slag part cannot be abruptly changed.

c.Both the capacitor terminal voltage and the inductor current are finite values.

d.The voltage at the capacitor terminal and the inductor current are roughly determined.

Correct answer: Both the electric field energy and the magnetic field energy have limits of change.

The inductor current can not be abrupt and the cause is ().

a.The inductor voltage is subject to the law of commutation.

b.The inductor current is a finite wisdom width.

c.The rate of change of the energy of the magnetic field is a finite value.

d.The rate of change of the energy of the electric field is a finite value.

Correct Answer: The rate of change of the energy of the magnetic field is a finite value.

The charge on the plate of the capacitor has a hindering effect on the charge moving in the direction, which is called capacitive reactance. It is precisely because of the existence of capacitance that the capacitor is not charged nonlinear, the rate of change of the current at the beginning of the charge is large, but the energy is conserved, and the voltage at both ends of the capacitor is small at the beginning of the rate of change, that is, the change is relatively smooth, and the current is supposed to correspond, saying that the voltage at both ends of the capacitor can not change abruptly, so the current is ahead of the voltage.

The charge on the plate of the capacitor has a hindering effect on the charge moving in the direction, which is called capacitive reactance. It is precisely because of the existence of capacitive reactance that the capacitor charging is nonlinear, and the change rate of the starting charging current is large, but the energy is conserved, and the voltage at both ends of the capacitor is starting to change at a small rate, that is, the change is relatively smooth, and the current wants to correspond, saying that the voltage at both ends of the capacitor can not change abruptly, so the current is ahead of the voltage.

In layman's terms, that is, because the capacitor voltage and energy are directly related, because the energy cannot be abruptly changed, the voltage cannot be abruptly changed. The existence of voltage is equivalent to the existence of an electric field, and the energy of the electric field exists, and the greater the voltage, the stronger the electric field, the greater the energy, if the voltage is zero, the energy of the capacitor is also zero. In addition, it is precisely because of the relationship between the voltage of the capacitor and the energy of the electric field that it is an energy storage element, and when the voltage remains unchanged, the energy it has can be stored between the plates and will not disappear.

In addition, it is precisely because of the relationship between the voltage of the capacitor and the energy of the electric field that it is an energy storage element, and when the voltage remains unchanged, the energy it has can be stored between the plates and will not disappear. The so-called capacitor charging and discharging failure is actually the process of capacitor voltage change, thereby changing the electric field energy.

There are many types and specifications of capacitors, but they are composed of two metal plates spaced apart by different insulating media (such as mica, insulating paper, air, etc.), just like sandwich biscuits, as shown in Figure 1-1. When the electric container is connected to a voltage, the two metal plates (plates) will accumulate the same amount of positive and negative charges due to the presence of voltage. At the same time, the presence of voltage must establish an electric field, so the two plates of the capacitor will build an electric field in the medium and have electric field energy.

The principle that the current can not be abrupt and the voltage at both ends of the capacitor cannot be abrupt

1. Inductance coil.

When the voltage is turned on, a back electromotive force equal to the applied voltage is instantaneously generated.

Blocking the flow of electric current.

Second, the magnetic field formed by the inductance coil must always maintain the current in the coil.

Summary: It is easier to understand that the voltage of the capacitor cannot be abrupt, because the voltage at both ends of the capacitor is formed by the accumulation of charges on the two plates, and the accumulation of charges cannot be completed instantaneously, and a charging process is required, and the DC power supply charges the capacitor through a certain circuit.

As the charge accumulated by the capacitor increases, the voltage at both ends of the capacitor gradually increases until it is equal to the power supply voltage, and the charging current stops, so the voltage does not change abruptly.

Inductors. An inductor is a component that converts electrical energy into magnetic energy and stores it. An inductor is similar in structure to a transformer, but with only one winding.

Inductive appliances have a certain inductance, which only hinders the change of current. If the inductor is in a state where no current is passing through it, it will try to block the flow of current through it when the circuit is turned on;

If the telecommunication sensor is in a state where current is passing through it, it will try to maintain the current when the circuit is disconnected. The inductor is also known as the choke and reactor.

Dynamic reactors. Inductors are generally composed of a skeleton, windings, shielding cover, encapsulation material, and a magnetic core or iron core.