Research On Closed-Loop Control Strategy Of Six- Wave Bi-variants Continuous AC- AC Converter Speed Regulation System

This paper based AC variable frequency stepped frequency conversion in the bivariate traditions, further study of six pulse cycloconverter frequency conversion control strategies for continuous and closed loop control in speed regulation system.AC-AC variable frequency speed regulation system in six pulse the original bi-variants,frequency regulation are pre according to cosine nodical method principle, the off-line calculated at a particular frequency thyristor tube trigger sequence and trigger time,written as trigger, according to the trigger table for step frequency, using look-up table method frequency conversion, not only a large amount of calculation and complicated,but also frequency switching in several frequency contact published, and the frequency switching frequency of large span would cause the system to shock and impact.Therefore, this paper puts forward the control strategy of continuous variable, and joined the speed closed loop, the frequency adjustment to achieve closed loop.Firstly, according to the basic principle of cycloconverter, proposed in the statistical significance of the continuous variable frequency control strategy concept.According to the calculation rules of cosine crossing method, the offline calculation method for contact published online real time calculation of trigger time, and analyzes the load characteristics and the calculation method of back-porch trigger time, provides the theoretical basis for the continuous conversion strategy.Secondly, through the Matlab simulation and experiment respectively obtained voltage, current, speed waveform on-line calculation of integer division and the trigger time at any given frequency, and gives the simulation and experimental waveforms under the strategy of continuous variable frequency speed control, speed control effect is good, smooth transition.Finally, based on the continuous variable frequency, joined the closed-loop control in the bi-variants AC-AC variable frequency speed regulation system. Through Matlab/Simulink simulation control model of closed loop, in the speed of a given mutation and load mutation in two cases, closed loop control effect. According to the experimental results, show that the AC-AC variable frequency speed regulation system,continuous closed-loop variable frequency control strategies has good control effect, asmooth transition, high precision.