Farid Meibody-Tabar

Distributed Active Resonance Suppression in Hybrid DC Power Systems Under Unbalanced Load Conditions

Power-electronics-based hybrid dc power systems (HDCPSs) are increasingly used in many industrial applications such as land, sea, and air vehicles. In these systems, small dc-link and LC filter capacitors are of great interest for weight saving. Usually, in HDCPSs, there are constant power loads and negative dynamic impedance of these loads may generate unstable oscillations. Besides, the risk of resonance may be increased under unbalanced load conditions. In this paper, a distributed active oscillation suppression approach is presented. It is based on the analytical study of the linearized model of the studied system around the operating point. The studied system consists of one main dc source and one storage element supplying two loads: a permanent magnet synchronous motor connected to the dc link by a voltage source inverter and a resistive load supplied by a dc/dc converter through the same dc bus. The proposed approach is particularly used to overcome the resonance under unbalanced load conditions and allows reducing dc link and LC filter capacitors for weight saving. Simulations and experimentations are carried out which confirm the validity of the proposed approach.

Comparison Criteria for Electric Traction System Using Z-Source/Quasi Z-Source Inverter and Conventional Architectures

This paper deals with objective criteria to compare conventional electric traction systems composed of a dc-dc boost converter, a voltage source inverter, and a permanent magnet synchronous machine with alternative topologies such as Z-source inverter (ZSI) or quasi Z-source inverter (QZSI). Rather focusing only on efficiencies issues, this paper deals with other relevant criteria. The stored energy in the systems is for instance linked with their passive elements weight, size, or cost. The currents rms values and the stepup voltage ratio are also considered. A complete losses evaluation is given and validated by both simulation and experimental results. The results show that the QZSI exhibits real advantages in terms of passive elements size since the stored energy during one operating cycle is lower than that for the conventional topologies.

A Novel Quasi-Z-Source Inverter Topology With Special Coupled Inductors for Input Current Ripples Cancellation

This paper proposes an inductors coupling technique to cancel input current ripples of a quasi-Z-source inverter (ZSI) without adding any additional components. The source input filter thus might be suppressed. This remains valid whatever the boost factor value. This cancellation property is made possible by a suitable coupling of the two existing quasi-Z-source inductors according to mathematical condition. The considered system in this paper is an electric drive system composed of a motor fed by the proposed coupled quasi-ZSI. An experimental prototype to validate both the theoretical and simulation analyses has been developed. The results have validated the proposed coupling strategy and show that it does not degrade the global efficiency of the system.

Efficiency Improvement of a Quasi-Z-Source Inverter-Fed Permanent-Magnet Synchronous Machine-Based Electric Vehicle

This paper proposes an improved control strategy for a quasi-Z-source inverter (QZSI)-fed permanent-magnet synchronous machine (PMSM)-based electric vehicle. The proposed strategy aims to improve efficiency of the powertrain with this particular dc/ac converter. For this purpose, it is proposed to adapt in real time the dc-bus voltage to the mechanical speed of the machine. The strategy is realized by implementing a control method based on the flatness properties of the system. These particular properties allow mastering all the state variable or input variable trajectories, which is interesting in the present case where the dc-bus voltage trajectory has to be well known. In order to increase the control dynamic, a one-loop flatness-based control is implemented. The structure thus allows increasing the controller bandwidth that helps in reducing the size of the dc-bus capacitors. Simulations and experiments on a 500-W powertrain are carried out to show that the proposed control strategy is effective and provides an efficiency improvement.

Stator winding inter-turn fault detection using control voltages demodulation

In this paper, a new technique for stator winding inter-turn fault detection in current controlled Permanent Magnet Synchronous Machines is proposed. The method is based on the online extraction of the second harmonic component of the voltage reference vector in the d-q frame. It will be shown that the amplitude of this harmonic depends on the inter-turn fault severity and the fault detection is realized by comparing the amplitude of the second harmonic to a threshold. This is a low cost method in CPU time. The experimental results show the validity of the proposed method.

Soft-switched quasi-Z-source inverter topology for variable speed electric drives

A novel bidirectional soft switched quasi-Z-source inverter is presented in this paper. By using a resonant capacitor and coupled inductors, the proposed quasi-Z-source inverter topology provides a solution to hard-switching problems for hybrid electric applications. The presented topology allows soft switching operations which aims at reducing the inverters active devices switching stresses as well as mastering the slew rate dv/dt that have a negative effect over the motor windings. The effectiveness of the proposed topology has been analytically studied and simulated in Matlab/Simulink and the results have been validated by experiment for both motoring and generating modes.

Hybrid data-based/model-based inter-turn fault detection methods for PM drives with manufacturing faults

In this paper, improved online inter-turn fault detection methods are proposed in order to take into account some design specifications related to recent Permanent Magnet Synchronous Machine (PMSM) topologies having modular stator combined with Fractionnal Slot Concentrated Winding (FSCW). This winding allows compact PM motor mainly by reducing end windings. It is often associated with segmented stator in order to simplify the construction of the motor as in the case of Electro-Mechanical Actuators (EMA). This technique may lead to the presence of manufacturing faults such as additional air gaps between the various parts of the modular stator. This urges users to consider complex models of PMSM far removed from classical dq models. Consequently, undesirable harmonics, torque ripples can interfere with fault detection such as inter-turn fault detection algorithms. This paper proposes invasive methods interacting with PMSM control using both model-based and data-based methods in order to take into account these aspects for control and online inter-turn fault detection. Various experimental tests on an industrial EMA prototype validate the effectiveness of the proposed solution.

Comparison criteria for electric traction system architectures

This paper deals with objective criteria to compare conventional electric traction systems composed of a DC-DC boost converter, a Voltage Source Inverter and of a Permanent Magnet Synchronous Machine with alternative topologies such as the Z-source or Quasi Z-source inverters. Analytical expressions are given and validated by both simulation and experimental results (efficiency).

A large signal stabilizer for high damping performance of PWM load converter with input LCL-filter

This paper develops a robust tool for the treatment of AC side stability problems occurring in interconnecting PWM voltage source converter with passive LCL filter. An LCL filter can reduce the harmonics introduced by PWM switching frequency and guarantee low currents THD using small component values comparing to the L filter solution. Nevertheless, the additional poles introduced by the LC part induce resonance in the system, leading to stability problems. To deal with this problem, in this contribution, a large signal stabilizing supervisor based on the indirect Lyapunov theory will be designed. The main objective of this stabilizer is to ensure both efficiency and robustness damping proprieties by the using of the Lyapunov method for the generation of power stabilizing signals. The stability phenomenon is highlighted and the effectiveness of the global stabilizer is validated by experimental results.

Stability and stabilization of permanent magnet synchronous machine fed by Quasi-Z-source inverter

Abstract This paper deals with the study of both the stability and stabilization of an electric drive system composed of a permanent magnet machine fed by a quasi-Z-source inverter. Quasi-Z-source inverters are DC-to-AC converters that are able to step up the DC-source voltage. They can be used to adapt the DC-bus voltage to the power or the speed of the machine that they feed. This ensures the controllability of the machine over a large speed range without using field weakening strategies. This also leads to inverter losses reduction. When the DC-source voltage is large enough to control the machine, there is no need to step it up. The quasi-Z-source inverter is thus assimilated to a simple LC filter. Some stability problems can thus appear and this paper presents a way to solve them by implementing stabilization strategies aiming at having an optimal functioning of the system.