Common Problems of DC Power Supply
1, What are the similarities and differences between DC power supply, single-phase power supply, AC power supply, and three-phase power supply?
A DC power supply has two electrodes, positive and negative. The positive electrode has a high potential and the negative electrode has a low potential. When the two electrodes are connected to the circuit, they can maintain a constant potential difference between the two ends of the circuit, thus forming a current from the positive electrode to the negative electrode in the external circuit, such as dry batteries and rechargeable batteries
Phase is phase. There are three live wires and one neutral wire coming out of a power plant, and the phase difference between the three live wires is 120 degrees. Single phase electricity refers to one of the live wires and the shared neutral wire.
The voltage between the single-phase live and neutral wires is 220V, while the voltage between the three-phase live wires is 380V, which is the standard in China. The voltage waveform is a sine wave Vt=Vrms * SIN (wt+A).
Three phase electricity is a live wire, and it's impossible to touch either one. The voltage between two wires is 380V, and the voltage between each wire and the neutral wire is 220V, which is what we use in our daily lives.
2, How to change the universal charging source to a DC power supply?
The two output lines of universal charging are DC positive and negative poles. As long as the voltage is appropriate and the current is not overloaded, it can be directly used as a DC power supply. For electrical appliances with high power requirements, voltage stabilizing and filtering electronic components can be installed between the connected appliances.
4, How to reduce the voltage of DC power supply?
By using 7805, a voltage of 5V or a current of 1A can be obtained. Generally, a heat sink is required. The voltage drop of each secondary pole of a series diode is about 1V.
It is better to use 12-5 DC-DC batteries. 7805 is a linear power source, which is too wasteful of electricity. Nowadays, DC-DC can achieve an energy utilization rate of over 90%.
Is the household power supply DC power supply?
The household power source is AC power, while dry batteries are a typical DC power source. Direct current refers to a current that does not undergo periodic changes in direction and time, but its magnitude may not be fixed, resulting in a waveform. Also known as constant current. The circuit passed through is called a DC circuit, which is a closed conductive circuit composed of a DC power source and a resistor. In this circuit, a constant electric field is formed. Outside the power supply, positive charges flow through a resistor from a high potential to a low potential. Inside the power supply, the non electrostatic force of the power supply overcomes the electrostatic force and then reaches the high potential from the low potential. This cycle forms a closed current line. So, in a DC circuit, the function of the power supply is to provide a constant electromotive force that does not change over time, to supplement the energy consumed by Joule heating on the resistor.
