The Research Of One-cycle Control Technology And Its Application In Active Power Filter

With the rapid development of power electronics technology, the usage of electronics equipment is increasing rapidly. These electronics equipments impose nonlinear loads to the ac main that draw reactive and harmonic current in addition to active current. Therefore, solving these problems has become an important task in power electronic disciplines. Acive power filter (APF) generates the compensating current which is equal to harmonic current in amplitude and opposite in polarity, which is thought of as a new equipment of cancelling harmonic, aim at cancelling the current harmonics and reactive components generated by the load. So active power filter has been studied widely and begin to industralise.One-cycle control method is a nonlinear control method, firstly provided by American researchers Keyue M. Smedley and Slobodan Cuk, which is perfect for switching control. Compared to the other PWM control methods, One-cycle control responses fast, it can reject power perturbations and the control circuit is simple and reliable. Therefore, the application of one-cycle control technique in active power filter supplies a new method for the control of active power filter.The problem of one-cycle control for active power filter is proposed based on the analysis of existing main circuit topology, harmful current detecting methods and current tracking control of active power filter in this paper. The application of one-cycle control technique in active power filter is discussed. Afterwards, some control models are built for active power filters. At the same time, some simulations are done.The research achievements of the single,three-phase three-wire,three-phase four-wire active power filters with one-cycle control are fully complied in this paper.Based on which the one-cycle control relationships and models of shunt and series active power filters in different phase are discussed. Especially, the one-cycle control models are proposed for the related active power filter respectively. Some simulations are done.The results of simulation proof the validity of theory analysis. In this paper, one-cycle control technique is used to the control of three-phase four-wire series active power filter with four-leg first time, on the basis of analysis and summary the previous research achievements. The analysis for the average model of the three-phase four-wire series active power filter in switching period is performed and the control equation is derived. The one-cycle control model of the three-phase four-wire active power filter with four-leg is built, the simulation is carried out. The results of simulation verify that the three-phase four-wire series active power filter with one-cycle control can dynamically and effectually compensate the harmonics, reactive current and zero sequence current and they have excellent compensating capability.