Two-level PWM Rectifier Research Articles

Sliding-Mode Observer Based Voltage-Sensorless Model Predictive Power Control of PWM Rectifier Under Unbalanced Grid Conditions

A sliding-mode grid voltage observer (SMGVO) is proposed and experimentally verified in this paper for voltage-sensorless operation under an unbalanced network. The fundamental positive sequence component (FPSC) and fundamental negative sequence component (FNSC) are inherently separated in the observer without employing any additional filters. Due to embedded filtering effect, high frequency chattering and harmonic ripples can be well suppressed. Additionally, dc components can be completely rejected. As a result, dc offset would not cause fundamental frequency oscillations in magnitude and frequency of the estimated FPSC and FNSC. Owing to the predictive ability of SMGVO, one-step delay can be directly compensated using state variables in the observer. By combining estimation and prediction into one stage, the designed SMGVO turns out to be a compact solution for finite-control-set model predictive power control without voltage sensors. Theoretical proof is derived to verify that FPSC and FNSC can be accurately estimated and separated. Experimental results obtained from a two-level PWM rectifier confirm the effectiveness of the whole control system.

DC Bus Control of Back-to-Back Connected Two-Level PWM Rectifier-Five-Level NPC Voltage Source Inverter to Torque Ripple Reduction in Induction Motor

This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI) in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC) voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

Study and Control of Three-Phase PWM Rectifier Based on Dual Single-Input Single-Output Model

A novel dual single-input single-output (DSISO) model for a three-phase two-level PWM rectifier is proposed, in order to simplify the complicated structure of multiple input variables and multiple control objectives. In the proposed model, the three-phase PWM rectifier is equivalent to two single-phase PWM rectifiers in the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\alpha-\beta$</tex></formula> stationary reference frame, which is easier to analyze than a three-phase PWM rectifier. Based on the DSISO model, the small-signal model is derived, the control-to-output transfer function is deduced, and the design principle of the voltage controller is given. The control strategy is analyzed to determine switching control signals in a switching period. Experimental results confirm the validity of the DSISO model and the feasibility of the control strategy based on DSISO model.