Automatic control principle How to find the gain factor

At that time, we were in an open-book exam, and it seemed very simple, that is, a few classic example problems in the book were changed to 2 2-so the remainder factor formula According to the Mason gain formula, the closed-loop transfer function of the system is (2) Ling, and the system is found.

Summary. Open-loop gain: refers to the amplification gain when no negative feedback circuit is added to the amplifier, and the gain after adding negative feedback is called closed-loop gain.

Is this the circuit aspect?

Yes. This is an automatic control method that automatically adjusts the gain of the amplifier circuit according to the signal strength.

Gone? I'm thinking about what to say.

The gain splits the loop and closes the loop.

Open-loop gain: refers to the amplification gain when no negative feedback circuit is added to the amplifier, and the gain after adding negative feedback is called closed-loop gain.

Closed-loop enhancement: In order to improve the performance of the basic amplifier, a reverse signal path is introduced from the output to the input end of the basic amplifier, and the network that constitutes this path is called the feedback network, and the signal of the reverse transmission mask key is called the feedback signal.

In the same system, the closed-loop gain must be smaller than the open-loop gain.

That should be the way it sounds.

Teacher, is there a simpler explanation?

What is this question for you, short answer questions.

What is inverse power?

An automatically controlled gain in which the gain of the amplifier circuit adjusts with the signal strength. In the amplification circuit, the open-loop material gain is not introduced into the reverse signal path, and the closed-loop gain is introduced in the reverse signal path, and in the same system, the closed-loop gain must be smaller than the open-cover Hui return loop gain. In the same system, the closed-loop gain must be smaller than the open-loop gain.

It can be explained this way.

The power direction of the reverse power generator should flow to the bus with the god for the generator, but when the steam turbine loses the original power due to various reasons, the generator becomes a synchronous motor operation, that is, absorbs the active power from the system, and this round is the reverse power.

What is the reverse power protection of a generator?

Generator reverse power protection, also known as power direction protection, is a kind of generator relay protection.

When the reverse power reaches a certain value, the protection action of the generator is either to signal or to trip.

The delay action of reverse power protection is to avoid the short-term and less serious "reverse power" that may occur during the merging operation.

If the received signal changes by a few V and a few mV, that is, the signal strength ratio is 10 to the third and 10 to the fourth power.

Reasons for change: different distances, different radio transmission power:

Mobile radio stations and short-wave signals fade, and the change in strength is relatively slow.

Due to the large change in signal strength, if the amplifier gain is fixed, it will cause:

1) Deviate the post-amplifier from the linear region and distort the signal

For example, the synchronization head of the TV signal is compressed or eliminated, so that the synchronization is out of control. In severe cases, large signal blockage (entering the cut-off, saturation zone) is generated

2) Increase the mixing combination frequency interference and nonlinearity

1. AGC circuit in the broadcast receiver.

2. High linear amplitude modulation in AGC mode.

Automatic Gain Control is an automatic control method in which the gain of the amplifier circuit is automatically adjusted according to the signal strength. Automatic gain control is a type of limiting output that uses an effective combination of linear amplification and compression amplification to adjust the output signal of the booster. When the weak signal is input, the linear amplification circuit works to ensure the strength of the output signal; When the input signal reaches a certain strength, the compression and amplification circuit is activated to reduce the output amplitude.

That is, the AGC function can automatically control the amplitude of the gain by changing the input-output compression ratio. AGC is subdivided into AGCI (Input Automatic Gain Control) and AGCO (Output Automatic Gain Control).