The Difference Between Direct Current And Alternating Current And The Scope Of Use

DC power has positive and negative poles, but AC power does not. The inventor of direct current was Edison, and the inventor of alternating current was Tesla.

Alternating current generally refers to a voltage or current whose size and direction change periodically over time. Its most basic form is sinusoidal current. Refers to the current whose direction and time do not periodically change, but the current may not be fixed in size, resulting in a waveform.

In daily life, the sockets at home and the meters on the street are all alternating current. It seems that there is no intersection between alternating current and direct current, just like two different fields. In fact, there are many, many connections between them.

Alternating current can be converted into direct current.

AC can be changed to DC. The computers, mobile phones and other devices we usually use are directly connected to the sockets with AC power, while our mobile phones and computers run DC power. So, there are doubts. Since the grid uses AC power for power generation and transmission, why is it now turned into DC power at this time?

The reason is this. The communication fluctuates in a sine law on the time axis, rising from 0 to the maximum, then gradually decreasing from the maximum to 0, then gradually changing from 0 to the negative maximum, and then returning to 0. However, our mobile phones, computers and other electronic components work by identifying high and low potentials. Due to its sinusoidal fluctuation, alternating current will generate high and low potentials, which conflicts with the logical judgment of electronic components. For example, in a computer, if there is a potential, it is 1, and if there is no potential, it is 0, and the alternating current itself has a zero-crossing potential. Therefore, alternating current cannot work for electronic components.


So, who will complete the work of converting AC to DC? The rectifier, as shown in the figure below, is a common rectifier product.

Common rectifier

Are DC and AC really opposed forever?

When using electrical appliances such as computers, we need to use a rectifier to convert AC to DC for use. For example, in the washing machine we usually use, the drive motor uses alternating current, and the rectified direct current is on the control panel.

Direct current can also be converted into alternating current

So, will there be a scene where DC changes to AC? The answer is yes. The inverter is a device for converting direct current to alternating current. Simply put, the inverter is composed of an inverter bridge, control logic and filter circuit. It is widely used in air conditioners, home theaters, electric grinding wheels, computers, TVs, etc. For example, car air conditioners need inverters to convert the DC power in the car battery into AC power to work. The following picture shows a 1000W inverter product.

Mother Company: Guangdong Super Telecom Co., Ltd. (Stock No. SH.603322)

Business Type: ISO 9001:2008 and ISO 14001:2004 certified Manufacturer

Main Products: Telecom SCADA; Energy Meter; RTU; Cabinet air conditioner; CRAC

Total Annual Revenue: US$ 14 Million-US$20 Million

Main Market: Asia, South America, Europe

Location: Chengdu, China (Panda’s homeland)

Year Established: 2010

R&D Achieves: 16 product patents; 6 software copyrights

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