ANALYSIS OF SINGlE-MACHINE UNINTERRUPTIBLE SUPPLY SCHEME USING SIX-PHASE SYNCHRONOUS MACHINE

Abstract

For greater reliability and overload capacity in uninterruptible power supply , (UPS) scheme application of six-phase synchronous machine is analysed in this present work. Six-phase synchronous machine not only has higher power/weight ratio but its power output is also almost double for the equivalent three-phase synchronous machine. Various characteristics of six-phase synchronous machine useful in UPS scheme are j discussed. The two sets of windings are simulated in differ nt motor and generator mode and behaviour of output power, torque angle and speed is analyzed. The present work deals with single machine UPS scheme and the development of control circuitry for the inverter fed six-phase synchronous machine so that output frequency deviation and voltage dip be minimized. Finally, merits of six-phase synchronous machine is discussed for the proposed six-phase synchronous machine based single machine UPS scheme. (iv) machine. This system consists of a current source inverter, a six-phase (double wound) synchronous machine, a position sensor and a control circuit. A six-phase synchronous machine with a controlled bridge rectifier connected to one set of stator windings is increasingly being used in novel AC-DC power supplies With mechanical power input,, the six phase machine is able to supply AC power from one stator set and DC power through the rectifier connected to the another stator set. Such AC-DC generators have been proposed as power supplies on air crafts and ships because they not only cost and weigh less in comparison to alternative three phase generator transformer rectifier set but also require less filtering. Beside this, the rotor inertia also helps to smoothen out fluctuations in the energy transfer. When only DC power input is available, the same configuration operated as an inverter can replace DC motor/AC generator sets for less weight and maintenance requirement. 1.2 Literature Review Now a days for obtaining higher reliability and distortion free UPS, the six-phase synchronous machine based uninterruptible power supply can be used. This novel single machine UPS scheme has advantages over two or three machine types UPS. Knight et al. [11] have traced the evaluation of uninterruptible power systems (UPS) from their beginning to the present time and take a look into possible future systems and requirements. The need will remain, however for UPS that is 100 percent reliable and require little or no maintenance.