Medium and high power switch mode power supplies SMPS (>500W) used in telecommunications stations are normally based on the full-bridge DC-DC converter with isolation transformer. According to the transistors states, the full-bridge converter allows four different switching sates which can be used to control the output voltage of the SMPS, and to perform the power factor corrector (PFC) functio...

Reactive energy and power factor L2 1.1 The nature of reactive energy L2 1.2 Equipment and appliances requiring reactive energy L2 1.3 The power factor L3 1.4 Practical values of power factor L4 Why to improve the power factor? L5 2.1 Reduction in the cost of electricity L5 2.2 Technical/economic optimization L5 How to improve the power factor? L7 3.1 Theoretical principles L7 3.2 By using what...

Various inductive loads used in all industries deals with the problem of power factor improvement. Capacitor bank connected in shunt helps in maintaining the power factor closer to unity. They improve the electrical supply quality and increase the efficiency of the system. Also the line losses are also reduced. Shunt capacitor banks are less costly and can be installed anywhere. This paper deal...

To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is introduced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the deficiency of control strategy, the contr...

This thesis focuses on the study, implementation and improvement of a digital controller for a power factor correction (PFC) converter. The development of the telecommunications industry and the Internet demands reliable, cost-effective and intelligent power. Nowadays, the telecommunication power systems have output current of up to several kiloamperes, consisting of tens of modules. The high-e...

The NCP1612 is designed to drive PFC boost stages based on an innovative Current Controlled Frequency Fold−back (CCFF) method. In this mode, the circuit classically operates in Critical conduction Mode (CrM) when the inductor current exceeds a programmable value. When the current is below this preset level, the NCP1612 linearly decays the frequency down to about 20 kHz when the current is null....