Development of efficient power supply for microprocessors using zero voltage switching

Abstract

In order to meet the market demand for faster personal computers and laptops, microprocessor manufacturers are increasing the clock frequency at which the processor operates. And since the technology used is CMOS (Complementary Metal Oxide Semiconductor), the power dissipation of the microprocessor increases linearly with clock frequency. For very powerful processors, conventional heat dissipation methods are insufficient. Normally, a combination of power supply voltage reduction and selective clock speed reduction is used to reduce power dissipation. Thus special power supplies are used that would supply low voltages and high currents to meet the increasing load demands handled by the microprocessor. This work presents a reliable and efficient low voltage high current Voltage Regulator Module (VRM) for devices using microprocessors like desktop computers, laptops and tablets. The Switched Mode Power Supply (SMPS) generally used in computers essentially converts the input AC supply into ±12 V or ±5 V DC supply but to step this DC voltage down to further low voltages (1.2 V), synchronous converters are the obvious choices owing to their low conduction and switching losses. In this project the various losses occurring in the standard buck converter, synchronous buck converter and multiphase synchronous buck converter (MSBC) is analyzed. It is then found that the high side switching loss dominates the total loss. Also, ZVS (Zero Voltage Switching), the most efficient soft switching technique is employed along with a SBC to form an efficient power supply. The suggested ZVS SBC is then simulated using PSIM for design values of 3.3 V, 12 A output and a 200 kHz switching frequency. It is seen that this converter provides an efficient output as compared to a conventional SBC. Moreover, the resonant circuit is devoid of the switching loss. With this satisfactory result, the increase in efficiency of SBC along with ZVS is realized in this dissertation.