Savvas Tsotoulidis

Deployment of an Adaptable Sensorless Commutation Technique on BLDC Motor Drives Exploiting Zero Sequence Voltage

This paper introduces an improved signal processing technique of zero sequence voltage (ZSV) with the scope of position sensorless commutation of a BLDC motor drive system. Rotor position information is extracted in the proposed technique from ZSV. This signal includes all time intervals where back electromagnetic force (EMF) zero crossings (ZCs) occur, from which the commutation instants are determined. This technique exploits maximally flat group delay of Bessel low-pass filters for switching noise suppression. This attribute leads to a speed-independent time displacement of ZSV. The fundamental frequency of ZSV is determined through a median-filtering algorithm, which is required for a dynamic rate limiter that eliminates erroneous ZCs. In sequence, a pulse train is generated by the detected ZCs of the emerged signal and properly shifted to determine the correct commutation instants. The proposed technique ensures a wide operational speed range for the drive system. A theoretical analysis of the drive system is presented, considering a BLDC motor with nonideal back-EMF. Experimental results presented in this paper validate the effectiveness and robustness of the proposed position sensorless commutation technique under various operational conditions.

Design of a wavelet multiresolution controller for a fuel cell powered motor drive system

A multiresolution wavelet-based controller for regulating the DC-link voltage of a fuel cell powered electric drive system is presented in this work. The system consists of a PEM fuel cell stack, an interleaved boost converter and an inverter driving a brushless DC motor. Control of the DC bus voltage is critical owing to the strong dependence of the voltage produced by the PEM fuel cell from load variations. Using a wavelet based controller gives the advantage of good control dynamics, while, due to the nature of the controller, the use of a filter in the measured output is avoided. Simulation results show that the proposed controller has fast transient response and satisfactory operation under steady state conditions.

Side-effects of Hall sensors misplacement on BLDC motor drive operation

In this paper, the impact of Hall sensors misalignment on BLDC motor operational characteristics, i.e. DC bus current, electromagnetic torque and system efficiency, is investigated. A method for identifying and evaluating Hall sensors misplacement is described. The BLDC motor drive system is simulated in Matlab/Simulink environment software with ideally and misplaced positioned Hall sensors. Typical scenarios regarding Hall sensors angular misplacement have been simulated for the most commonly mounting configurations. The electromagnetic torque spectrum as an indicator for mechanical vibrations and noise generation has been examined. Simulations results indicate that system efficiency is decisively decreased as angular misplacement becomes greater than 30o electrical degrees.

Comparative study of three types of step – up DC - DC converters for polymer electrolyte membrane fuel cell applications

In this work, the suitability of three dc-dc converters for application in a PEM fuel cell system is examined. Investigation of boost converter, interleaved boost converter and interleaved boost converter with switch capacitors takes place. The efficiency of each converter at different load values is compared and the harmonic content that each of them produces is examined. Two different scenarios are presented. In the first one the system was designed to generate a converter output voltage of 50 V and in the second the output voltage is 100 V.

Demagnetization faults analysis in a BLDC motor for diagnostic purposes

This paper investigates a surface inset-permanent magnet brushless DC motor with fractional-slot winding configuration driven by a three-phase inverter under different types of defected magnets. The comparative study on demagnetization faults is carried out using FEM analysis. The number of damaged magnets, their relative position in the rotor surface and their demagnetization level are studied for diagnostic purposes. The harmonic components of the stator current and torque spectrums are considered as diagnostic means of the demagnetization faults. The influence of different types of demagnetization faults on the electromagnetic behavior of the BLDC motor is also investigated exploiting FEM analysis.

Multiresolution PID control of Brushless DC motor in fuel cell electric vehicles

The exploitation of wavelet theory in a control structure of a Brushless DC (BLDC) motor integrated in a Fuel Cell Electric Vehicle is proposed. The controlling structure, consisted of two interrelated multiresolution PID (MRPID) controllers, regulates: a) BLDC motor torque through DC current and b) rotor speed. The proposed structure is deployed on an algorithm that exploits inherit wavelet filtering capabilities for improving control dynamics and stability over a wide operational range. Full system (FCEV) performance is assessed for both cases of MRPID and conventional PID controlling structures via simulation in MATLAB/Simulink environment.

Analysis of a wind energy conversion system with Doubly-Fed Induction Generator in healthy and fault condition via simulation

In this paper, a wind energy conversion system that uses the “Cascade technology” especially the structure of Doubly-Fed Induction Generator (DFIG) is presented and analyzed. Moreover, a simulation of this wind energy conversion system under fault conditions in MATLAB/ SIMULINK is done and the results are evaluated. Open-circuit faults in one IGBT or in two IGBTs are studied.

Design and construction of a four-channel interleaved buck dc/dc converter for an electric boat application

This paper focuses on the design and construction of an electric drive system for an electric boat. A number of technical interventions were made to convert a simple boat to an electrically driven boat. In our days the electric boats and the electric propulsion in general constitute a part of the electric transportation. The electric transportation seems to be an alternative solution in the continuously increasing demand in the sector of transports as well as in energy and environmental problems. The high efficient electric machines and power electronic converters, the high control level of power electronics that offers manoeuvrability in a ship, the lack of noise — disturbance and the absence of pollution lead to the use of electric propulsion in boats and ships more and more nowadays. In the application, on account of practical and safety reasons we were led to the choice of a low voltage permanent magnet direct current (DC) motor. This is resulting to a high value of current to get the nominal power of 1.5 kW. For this reason an interleaved four — channel dc/dc converter was designed and constructed which has the ability to control high currents and can be considered as ideal for such type applications. The particular converter is constituted by 4 parallel channels, it is working in the continuous conduction mode (CCM) and it decreases the voltage of 36 V to 0–24 V to control the velocity of the dc propulsion motor which its full load current is 78 A. Firstly, simulation via PSpice program and also a number of experiments have been made to investigate the operation of the converter. The experiments show that the efficiency of the interleaved converter of the application is about 95 %, so it is a good solution for driving low voltage — high current dc motors. Such types of electric motors are used in electric transportation applications. The launching of the boat “PROTEUS” and a number of sea tests show the advantages of the electric propulsion.

Development of a novel Energy Management Strategy for Hybrid Electric Vehicles

Nowadays, in order to provide high efficiency products, automotive industry is looking towards Hybrid Electric Vehicles. Fuel Cells technology is considered to be a promising solution for on board power generation. However, FCs require auxiliary sources, such as Batteries and/or Ultracapacitors, in order to deal with the issue of fast load dynamics. Within that context, Energy Management Strategy is defined as a critical component of Hybrid Electric Vehicle, since it is responsible for energy sharing among the different sources. In this paper, a novel Energy Management Strategy is proposed that aims on current sharing between primary and auxiliary sources. This strategy is deployed in two stages through a set of rate limiter and a Fuzzy Logic Controller. The first stage defines the low harmonic component of current load demand and assigns it to FC, while the second determines which harmonic component of current load demand Ultracapacitor should cover. That procedure takes considerably into consideration energy stored in ancillary sources as well as load demands. Simulation results validate the efficiency of the proposed Energy Management Strategy.

Stress-oriented driver assistance system for electric vehicles

Stress is physiological and physical reaction that appears in highly demanding situations and affects humans perception and reaction capability. Occurrence of stress events within highly dynamic road environment could lead to life-threatening situation. With the perspective of safety and comfort driving provision to anxious drivers, in this paper a stress-oriented Driver Assistance System (DAS) is proposed. The DAS deployed on Electric Vehicle. This novel DAS customizes driving command signal in respect to road context, when stress is detected. The effectiveness of this novel DAS is verified by simulation in MATLAB/SIMULINK environment.