Rectifier (English: rectifier) is a device that converts alternating current into direct current. It can be used for power supply devices and radio signal detection. The rectifier can be made of vacuum tube, pilot tube, solid silicon semiconductor diode, mercury arc, etc. On the contrary, a device that converts direct current into alternating current is called an "inverter".
In the standby UPS, only the battery needs to be charged, and the load is not required to supply power, so there is only a charger. In a double conversion UPS, this device not only supplies power to the inverter, but also charges the battery, so it is called a rectifier/charger.
A rectifier is a rectifier device, simply put it is a device that converts alternating current (AC) into direct current (DC). It has two main functions: first, it transforms alternating current (AC) into direct current (DC), which is filtered and supplied to the load or to the inverter; second, it provides charging voltage to the battery. Therefore, it also acts as a charger at the same time.