Unity Input Power Factor Operation Research Articles

Imposed Source Current Predictive Control for Battery Charger Applications with Active Damping

This paper presents an imposed source current predictive control approach for a current source rectifier that can be used as battery charger fed from three-phase ac grid. The proposed MPC technique allows to charge the battery with a constant current or voltage as what is required for cyclic charge process of batteries. The proposed technique ensures unity input power factor operation for grid side. The single-objective cost function of the predictive control employs the error between supply current reference and supply current prediction and the switching state that minimizes this cost function is selected among the nine switching vector combinations of the current source rectifier so as to apply for next sampling interval. An active damping current term, that is predicted from the input filter capacitor voltage estimation is included in the cost function to mitigate the resonance of input LC filter. The supply current references in phase with grid voltages are generated from grid voltages and the amplitude of this reference currents are generated from the charging requirements of the battery. The input filter model is used to predict the filter capacitor voltages at sampling intervals k and k+1 in order to eliminate sensor requirement for them. A simulation study is carried out to observe the proposed method in terms of steady-state and dynamic responses and supply current quality.

PWM-based Integral Sliding-mode Controller for Unity Input Power Factor Operation of Indirect Matrix Converter

PWM-based Integral Sliding-mode Controller for Unity Input Power Factor Operation of Indirect Matrix Converter

Unity Power Factor Operation of Indirect Matrix Converter Tied to Unbalanced Grid

This paper presents a new control method for indirect matrix converter operating under unbalanced grid voltages. The proposed method aims to achieve balanced output voltages as well as a near unity input power factor operation. First, an opportune reference current accurately generated, and a proportional integral resonant controller are designed in a dq reference frame that is synchronized with the positive sequence of the grid voltages so as to achieve a perfect tracking of input reactive power reference. Then, a real-time estimator of the virtual dc-link voltage is developed with the aim to provide balanced output voltages; therefore, an almost constant active power free of low frequency ripple is supplied from the grid. Experimental results are presented to verify the feasibility and effectiveness of the proposed control method.

A hybrid controller for PWM active rectifiers based LCL filters

Purpose – The purpose of this paper is to propose a new hybrid control method of pulse width modulation (PWM) active rectifiers tied to the grid through an LCL filter. The control method is designed with the aim to achieve a perfect regulation of the dc-bus voltage; a near unity input power factor (UIPF) operation as well as a high quality of the line currents. Design/methodology/approach – The proposed hybrid control method consists of a PI-based linear controller cascaded with a nonlinear one. The nonlinear controller (inner loop) is designed using the input-output feedback linearization (IOFL) theory. It should control both the dc-bus voltage and the input currents at the converter’s poles. The linear controller (outer loop) is devoted to control the reactive line current so as to achieve a near UIPF. Findings – A perfect regulation of the dc-bus voltage and a near UIPF operation are achieved. Moreover, a high quality of the line currents is obtained. The robustness and effectiveness of the proposed control method have been successfully tested under variation of the dc voltage reference as well as grid and load disturbances. Practical implications – The proposed method is useful for single-stage and two-stage grid connected photovoltaic systems, wind energy conversion, and distributed power generation systems. Originality/value – The main novelty of this paper is the combination of linear and nonlinear controllers with the aim to control a PWM active rectifier tied to the grid through a third-order LCL filter. In the opinion, such control method has not been applied to this converter in earlier research papers. The numerical simulations carried out under normal and abnormal conditions confirm the effectiveness of the proposed approach.

A reduced hysteresis controller for a four-switch three-phase bidirectional power electronics interface

A reduced hysteresis controller for a four-switch three-phase bidirectional power electronics interface is proposed in this letter. Polarity detection of the input voltages to determine the switching states is not required. The circuit is simple. Experimental results show unity input power factor operation and bidirectional power transfer capability.