Switched mode power supply (SMPS): Working Principle of SMPS  ITI’s 50V – 2000A Power Plant?

Functional Description of Rectifier

The Switched mode power supply (SMPS) 50V-5600W rectifier is state-of-the-art switch-mode power conversion equipment. The unit comprises two cascaded power converters performing power factor correction and DC/DC conversion. The power stages are synchronized and work with a constant switching frequency of 100 kHz.

The rectified AC mains voltage is processed first in the power factor corrector circuit, which is based on a boost topology. The boost converter has the inherent advantage of continuous input current waveform, which relaxes the input filter requirements. A proprietary snubber circuit, which reduces the switching losses of the power semiconductors because non-zero switching times improve the performance of the basic boost cell. The snubber circuit also decreases the electromagnetic interference (EMI) generated primarily during the turnoff process of the boost diode. The output of the boost converter is a stabilized 400V DC voltage.

Further conversion of the stabilized high voltage output of the power factor corrector circuit is necessary to generate the isolated low voltage output and to provide the required protection functions for telecommunication applications. These tasks are achieved in the DC/DC converter circuit which is based on full-bridge topology. The full-bridge circuit is operated by phase-shift pulse width modulation with current-mode control. This control method provides zero voltage switching conditions for all primary side power semiconductors, effectively reducing switching losses and electromagnetic interference. An advanced solution reduces the stresses of the output rectifier diodes.

Proper operation of the power converters is managed by individual controller circuits and supervised by housekeeping electronics.

Remote commanding and monitoring of the modules are possible through a power system controller housed in the system.

Functional Description of Power System Controller

The power system controller is designed to control the modes of operation of rectifiers, acknowledge and display the status of rectifiers and system, and controls parameters of rectifiers.

The controller accepts signals from individual rectifiers through 8 pin telephone jack and controls the operation of each individual rectifier.

The mode of operation of rectifier modules depends on the coded signal M1 and M2 from the controller. Depending on the state of the batteries, the ATM circuit either gives a signal for float or charge. These signals are encoded by an encoder to obtain suitable coded signals M1 and M2.

Depending upon the mode of operation of Rectifier modules, they acknowledge coded signals S1 and S2. These signals are decoded to display whether the modules are in auto float/charge or fail condition.

The total battery current can be suitably programmed to limit the current supplied from the modules through the current programming pin in modules.

Switched mode power supply (SMPS) 48V – 5600W – Introduction

The Switched mode power supply (SMPS) 48V-5600W is a three-phase, unity power factor power supply with a wide input voltage range of 3 X 185 Vac to 275 Vac (with neutral wire) and with a useful output power of 5600W delivered to the load. This unit has been developed for cost-effective but highly intelligent modular telecommunication power systems. It fulfills the specification of


A primary application of the rectifiers SMPS 48V-5600W are in the supply of Telecom equipment. The convection cooled unit may be operated up to 60oC ambient air temperature.

The rectifier operates from a nominal 3 X 230 Vac rms (with neutral wire) source. The mains frequency may vary from 45 Hz to 65 Hz. The total harmonic distortion (THD) of the input current waveform is below 5%.

The output of the rectifier conforms to the generic requirements of telecommunication power supplies in terms of noise, voltage programmability, as well as over-voltage, overload, and short-circuit protection. The rectifier SMPS 48V-5600W can be set in the 3 modes ‘auto float’, ‘auto charge’, and ‘manual boost’ by the power system controller.

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