The Switching Mode Rectifier (SMR) is a compact, high-efficiency high-frequency switching power supply device designed
to convert alternating current (AC) into direct current (DC).
After being filtered, the DC power is supplied to the load. Its small size, high efficiency, and ease of expansion, mobility,
and installation make it highly versatile.
High-frequency switch rectifiers, thanks to their benefits of compact size, lightweight, high conversion efficiency, stable
output, and adjustable features, have become prevalent in
communication equipment as power supply and conversion devices.
Compared with traditional rectifiers, high-frequency switching rectifiers (taking EVS 48V as an example) have the following advantages:
(1) Traditional power frequency transformers and reactors have been eliminated, resulting in smaller size and higher technical specifications.
(2) Capable of stable voltage and current limiting operation. The communication input adopts power factor correction technology to make
the input current close to a sine wave and reduce the impact of low order harmonic components on the power grid. Meanwhile, EMI filtering
can effectively prevent high-frequency interference from entering the AC system. The rectifier can charge the battery pack and
operate with load at the set voltage value and current limit value. When the output current exceeds the current limit value,
the rectifier automatically enters a steady current operation state; When the output current is less than the current limit value,
the rectifier automatically enters a stable operation state.
(3) Output voltage programmable adjustment function. Add an adjustable DC voltage (-10~+10V) to the programmable voltage terminal
VP of the rectifier (shared with the output negative bus), and the output voltage will change at a slope of "-6.5V/V" (rectifier with rated
output voltage of DC 220V) or "-4V/V" (rectifier with rated output voltage of DC 110V) based on the output voltage reference value set
inside the rectifier. For example, in a rectifier with a rated output voltage of DC 220V (the output voltage is set to DC 230.0V at the factory),
a DC voltage of "-2.0V" (relative to the output negative bus) is applied to the programmable voltage terminal VP, and the output voltage of
the rectifier is 230.0V+(-6.5V/V) (-2.0V)=243.0V. Therefore, it has a wider range of applications.
(4) Hot swappable function. Multiple rectifiers working in parallel on the rack can be easily plugged in and out without affecting the normal
operation of other rectifiers, making inspection and maintenance more convenient.
(5) The protection function is more complete. When a rectifier is in the protective action state, its current sharing and external control functions
will automatically exit without affecting the normal current sharing operation of other rectifiers.
① Input protection. When the AC input power supply of the rectifier experiences overvoltage or undervoltage, the rectifier will automatically
shut down. When the AC input power supply returns to normal, the rectifier will automatically start.
② Output overvoltage protection. When the DC output voltage of the rectifier exceeds the specified DC output overvoltage protection value,
the rectifier will shut down and restart. Otherwise, the rectifier will be in a cycle of startup protection shutdown restart protection. When this
phenomenon occurs, the rectifier should be pulled out and repaired.
③ Overcurrent protection. The rectifier will automatically protect and shut down when overcurrent occurs. When multiple rectifiers are running
in parallel, if there is a short circuit in the output or the load suddenly increases, the rectifiers may experience overcurrent protection and restart
to operate in a current limiting state.
④ Short circuit protection. The rectifier is equipped with multiple current limiting protections, which can withstand continuous short circuits
without damage and have high reliability.
⑤ Temperature protection. When the temperature of the main components of the rectifier exceeds 75 ° C, the rectifier will automatically shut
down. After the temperature drops to normal, the rectifier will automatically start and enter normal operation.
⑥ Alarm and display. The rectifier is equipped with alarm indicators and fault output terminals, which will accurately display when a fault occurs.
Monitor System
The monitoring system is the monitoring center of the high-frequency switch type rectifier, which monitors and coordinates the work of each
rectifier module, detects various parameters of the system, processes alarm information, provides a human-machine interface for user operation,
and thus controls the operation of the entire power system. The structure of the monitoring system is shown in Figure 2. The monitoring system
mainly consists of an alarm module, RS485 and RS232 communication interfaces, and a microcontroller inside the rectification module.
The alarm module communicates with various rectifier modules through RS485 communication interface to monitor their operation. The alarm
module communicates and accesses the peripheral PC or terminal through the RS232 communication interface, and achieves "three remote" through a modem.