Micro controller Based Multi phase Sequence Detection System
The report describes various methods for determining the phase sequence of a multiphase system. The reference phase is chosen random from the multi-phase and is assigned the serial number 1. Then with the help of a general rule and a micro controller, the serial number of any other phase is determined. The discussion starts with the simple three-phase sequence detection and then proceeds towards multi-phase systems. To ensure that the multiphase sequence detector operates properly, multi-phase supply is needed for its testing. Hence generation of multi-phase sequences becomes a supplementary task. The report also presents various techniques of multi-phase generation along with their merits and demerits. Some experimental results are discussed and conclusions are made related to various methods discussed in the report. Correct sequence identification of a balanced multi-phase system is quite necessary in scientific experiments. For instance when two 3-phase AC generators are to be synchronized their phase sequences should be matched correctly. The conventional method uses sequence indicator, which generally operates on Induction motor principle. Also when the three-phase induction motor is desired to run in a certain direction, proper phase sequence should be applied to it. Here, an unbalanced 3-phase load is used for the purpose of sequence detection, but with the number of phases increasing, the sequence combination increases for n phases system .The number of wrong sequence combinations is {(n 1)! 1}, Thus, for n 3 as in case of six-phase or twelve-phase inverters, this method would no more work. The report describes a method, which uses micro controller and a simple the sequence indication method will be general rule to find the proper phase sequence of any balanced multi-phase system. In case of the unbalanced multi-phase system, relative positions of various phases with respect to reference can be determined by measuring the phase angle of each subsequent phase, the phase sequence then can be obtained by rearranging the phase angles in their ascending order. As discussed earlier, the multi-phase sequence detection system needs to be tested for its operation. Hence it is required to have a multi-phase generation unit. Poly-phase square oscillators supply square wave voltages of an equal amplitude and a suitable phase angle between them. Many times, the oscillator is of variable frequency and its output stage is a switching mode one. Therefore they could perform as a controlled Poly-phase power supply with various applications in power electronics, such as dc-dc converters and electrical motor drivers. A poly phase square wave oscillator that employs only one integrator for any number of generated phases, which uses the multi-hysteresis block as a new circuit component.
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