E. E. El-Kholy

Power Factor Correction Using Predictive Current Control for Three-phase Induction Motor Drive System

Abstract This paper presents the study of a three phase pulse width modulation inverter-fed induction motor drive with single phase utility input, with and without a power factor correction circuit (PFC). The PFC circuit is controlled with the proposed predictive current control. The effects of the PFC circuit on the magnitude of the input current, harmonic contents and input power factor of the AC drive system are studied. A comparative study of simulation and experimental results for the AC. drive system, with and without PFC circuit, is carried out. The experimental implementation of PFC control of the boost converter controlled three-phase IM drive system using DSP controller board DS1104 is achieved using the proposed predictive control. The proposed PFC control method used to achieve a low input line current harmonics, for obtaining a good power quality with a fast dynamic response for output voltage and line current.

Adaptive cascaded delayed signal cancelation PLL based fuzzy controller under grid disturbances

Phase Locked Loop plays a crucial role in synchronizing medium voltage converters. PLL has to precisely and continuously track the grid voltage vector angle and feed it to the converter control loop. Grid disturbances such as voltage dips, harmonics, DC-offset and frequency changes have undesired effects on the estimated angle and as a consequence, the rectifier behavior will be deteriorated. A robust PLL design is essential to provide high immunity to grid disturbances and enable for converter ridging-through during severe disturbances. Using pre-filters to mitigate the grid disturbances slow down the overall system dynamic performance. This paper presents a novel method to ride-through wide range of disturbances by combining an Adaptive Cascaded Delayed Signal Cancellation (CDSC) operator as a pre-filter with a Fuzzy Controller. The obtained results show that the proposed scheme has a great potential for synchronizing high power converters under highly distorted grids.

New current references calculation for dual vector controlled three level active rectifiers under asymmetrical voltage operation

This paper introduces an effective nonlinear current references calculation to enhance the performance of the dual vector control under asymmetrical grid for three level neutral point active (NPC) rectifiers. Maintaining the DC-link voltage at the desired level without oscillation is the main target for such kind of application. The asymmetrical grid voltage or voltage dip introduces negative sequence components with badly penetrates through the rectifier control loop casing DC-link to oscillate with twice grid frequency. Conventional vector control (VC) technique failed to meet the control targets under unbalance operation of grid voltage as twice grid frequency ripple pollutes the DC-link voltage. Dual vector control (DVC) concept is implemented to control the positive and negative sequence currents separately. The conventional DVC control scheme can be enhanced by incorporating line power losses for calculating the reference currents. Maintaining the DC-link voltage at the desired level without any symptom of twice grid frequency ripples is one of the control targets which can be achieved by selecting the proper constrains for calculating the current references. The proposed enhanced DVC scheme performance is verified under asymmetrical voltage dip test. The entire system is modeled and simulated with real system parameters of a 7 MW multilevel NPC-type active rectifier.