Mohd Junaidi Abdul Aziz

A new method for RFOC of Induction Motor under open-phase fault

From an energy conversion point of view, most of electrical machines including Induction Motors (IMs) can be modeled by an equivalent 2-phase machine model (d-q model). A 3-phase IM, with one of the phases opened (faulty 3-phase IM), can also be modeled by an equivalent 2-phase machine. If a conventional Rotor Field-Oriented Control (RFOC) for balanced IM is used for this faulty machine, considerable oscillations in the torque and speed will result. In this paper, a new technique for vector control of faulty 3-phase IM is presented. In the proposed method, the supposition of Lqs/Lds = (Mq/Md)2 = a2, which is normally applied in other FOC of unbalanced 2-phase IMs, is not used. Results showed that considerable improvements in the torque and speed responses are achieved, specifically in the reduction of the oscillations.

A simple vector control technique for 3-phase induction motor under open-phase fault based on GA for tuning of speed PI controller

This paper discusses a simple vector control technique for vector control of faulty 3-phase Induction Motor (3-phase IM under open-phase fault) based on Rotor Flux-Oriented Control (RFOC). It is shown in the adapted system for vector control of the faulty IM, it is essential for the speed PI controller coefficients to modify. For this reason, Genetic Algorithm (GA) is employed for tuning of speed PI controller. The results of this study show that the proposed drive system have acceptable good speed and torque responses.

Modeling and RFOC of faulty three-phase IM using Extended Kalman Filter for rotor speed estimation

This research discusses d-q model and Rotor Flux-Oriented Control (RFOC) technique for faulty three-phase Induction Motor (three-phase IM when one of the stator phases is opened). In the controlling technique, two transformation matrixes are applied to the equations of faulty three-phase IM. As a result, the equations of faulty three-phase IM become similar to the balanced IM. Therefore, by employing some modifications in the conventional block diagram of the balanced IM, faulty motor control is possible. Additionally, for high performance vector control of the faulty IM, an Extended Kalman Filter (EKF) is used for motor speed estimation. Simulation results demonstrate the validity and applicability of this technique to improve performance of the faulty IM.

A high power density soft switching bidirectional converter using unified resonant circuit

This paper proposes a high efficiency bi-directional converter with high power handling capability. Soft switching technique is endowed with all power switches by using an auxiliary unified resonant circuit. Zero voltage switching (ZVS) and zero current switching (ZCS) modes are implemented for all power switches in boost operation. For buck mode of operation, ZVS and ZCS are executed for most of the power switches. Voltage stresses for all of the power switches are significantly reduced. Additionally, the proposed converter has a high step up and step down gain compared to a conventional bi-directional converter. The circuit is simulated in PSPICE and performance parameters are measured and verified.

Rule-based supervisory control of split-parallel hybrid electric vehicle

Hybrid electric vehicles (HEVs) have been a hot topic of research over recent years due to their features whereby make them a feasible solution to tackle concerns regarding to global warming. HEVs powertrain control plays an important role to accomplish control objectives such as low emission and good vehicle performance. This paper presents a system-level simulation and rule-based supervisory control strategy of a Split-Parallel Hybrid electric vehicle (SPHEV) which can be regarded as Parallel-HEV powertrain family. Advance vehicle Simulator (ADVISOR) is used to determine the sizing and ratings of key components of SPHEV driveline to satisfy specific performance constraints. Then physical model of the vehicle of interest is developed and simulated in Matlab/Simscape environment. Subsequently, simulation results are presented and discussed in terms of their effectiveness and accuracy.

Modeling and speed estimation of a faulty 3-phase induction motor by using extended Kalman filter

This paper presents a modeling technique for a faulty 3-phase Induction Motor (3-phase Induction Motor IM under open-phase fault). The developed model has the same structure of equations as the balanced 3-phase model. It is shown that the model can be utilized to estimate the speed of a faulty IM based on an Extended Kalman Filter (EKF) estimation technique, which was developed for a balanced 3-phase IM. Simulation and experimental results are presented to show the validity of the proposed techniques.

Vector Control of Star-Connected 3-Phase Induction Motor Drives under Open-Phase Fault Based on Rotor Flux Field-Oriented Control

Abstract This article presents a technique for vector control of star-connected 3-phase induction motor drives with an open-phase fault (faulty 3-phase induction motor) based on the rotor flux field-oriented control method. In this method, two appropriate transformation matrices are applied to the equations of faulty induction machine. It is shown that the structure of the derived faulty induction machine equations is similar to the healthy 3-phase induction motor equations; make it possible to control a faulty machine with some modifications in the conventional controller. Hence, a modified rotor flux field-oriented controller that capable to control a star-connected 3-phase induction motor under open-phase fault is proposed. The performance of the proposed method is verified through simulations and experiments on a 1.5 kW star-connected 3-phase induction motor drive. The comparative results obtained from the simulations and experiments confirm the ability of the proposed control method in vector control of 3-phase induction motor during open-phase fault.

Improving start-up operation of sensorless DTC of induction machines using simple flux regulation

This paper presents a direct torque control drive system utilizing constant switching frequency controller (CSFC) with EKF based speed estimation. By employing CSFC instead of the conventional hysteresis controller, the torque ripple is reduced and constant switching frequency is achieved, and more importantly, the simple structure of DTC without any modification to the look-up table is maintained. The main contribution to the use of CSFC is on the improvement of speed estimation at start-up and low speed operations. This is accomplished due to the improvement in the stator flux regulation. The experimental results of the proposed system showed a significant improvement in speed and torque estimations at very low and zero speed and are comparable to a more complex implementation of DTC.

Experimental evaluation of FOC of 3-phase IM under open-phase fault

ABSTRACT This paper presents an investigation of a novel Field-Oriented Control (FOC) performance for star-connected 3-phase induction motor (IM) drives with an open-phase fault. The control system enables to work in healthy and faulty conditions without requiring any modifications to the conventional control structure but with modifications only in the control parameters. This introduced control topology leads to the mitigation of any speed and torque oscillations resulting from the asymmetrical conditions related with this type of fault. A comparative study for vector control strategy using the proposed and conventional methods is experimentally verified.

A high gain soft switching non-isolated bidirectional DC-DC converter

This paper proposes a switched capacitor based non-isolated zero voltage switching (ZVS) bi-directional dc-dc converter. By implementing a switched capacitor loop, it can provide high step up and step down gain. The converter is operated in continuous current mode (CCM) mode where all the power transistors are soft switched by means of dedicated auxiliary resonant networks. Each network consists of a low-rated power switch (with a body diode), a resonant capacitor and a resonant inductor. The resonant capacitors are further optimized for zero voltage switching (ZVS) turn off of the power switches. The ZVS turn on and turn off conditions are achieved for all power switches in the boost and buck mode of operations. In addition, the voltage and current stresses on the power switches are significantly reduced, thus enhancing the converter operation at high power applications.