In reality, the power adapter is more switching power supply, we learn the power adapter circuit, to learn to analyze the circuit, the next power adapter manufacturer YHY for you to explain the power adapter circuit in detail.
1. Channel state:
A path is a circuit in which a switch closes and a current flows through the load. In this state, the relationship between the terminal voltage of the power adapter and the load current can be determined by the external characteristics of the power adapter. According to the size of the load, it is divided into three cases: full load, light load and overload. The working state of the load under rated power is called rated working state or full load; Lower than the rated power of the working state called light load; The working state above the rated power is called overload. Because overload is very tolerant of late burn out electrical appliances, so generally do not allow overload.
2. Short circuit state
If the external circuit is switched on by a conductor with approximately zero resistance, then the power adapter is in a short-circuit state, in which the current in the circuit (short-circuit current)I≈E/R. As we know, the internal resistance of the power adapter is generally very small, so the short circuit current may reach a very large value, which will have the risk of burning the power adapter, must be strictly prevented, avoid happening.
The most common way to prevent a short circuit is to install a fuse in the circuit. The fuse in the fuse tube is made of low melting point lead tin alloy, silver wire. When the current increases to a certain value, the fuse is first blown, thus cutting off the circuit.
The terminal voltage of the power adapter in the short-circuit state is:
U = E - IR material E - E/R * R = 0
It can be seen that the main characteristics of the short-circuit state are: the short-circuit current is large, and the terminal voltage of the power adapter is zero.
It needs to be noted here that usually the internal resistance of the power adapter is basically unchanged and the value is very small, so it can be approximated that the terminal voltage of the power adapter is equal to the electromotive force of the power adapter. In the future, if you do not specifically point out the internal resistance of the power adapter, it means that the internal resistance is very small and can be ignored.
3. Open state
Open is the power adapter at both ends of the open circuit somewhere disconnected, no current through the circuit, the power adapter does not deliver electrical energy to the load. For a power adapter, this state is called no-load. The main characteristic of the open state is that the current in the circuit is zero. The terminal voltage of the power adapter is equal to the electromotive force.
These three states, can be seen everywhere in our life, such as the switch of the light, the light shining, this is a channel state, if open the light, at the same time open the refrigerator, air conditioning, rice cooker, TV, computer, speaker, frying pan, then the load is more, allow late overload phenomenon, when the overload wire easy to smoke fire. When the switch is turned on, the light goes out, which is an open circuit. And when the two wire (fire line, zero line) skin is damaged by rats, resulting in two lines together, will cause short circuit, if there is a flow switch, the flow switch immediately work, if there is no flow switch, immediately smoke fire.
