4,374 research outputs found
A novel enhanced connection of AC/AC powertrain for HEV - modelling and simulation results
The paper deals with a novel enhanced connection of AC/AC powertrain for Hybrid Electric Vehicles (HEV). The substantial contribution of such a connection is the absence of 4QC auxiliary converter needed for autonomous and hybrid operational modes and its compensation by power-lesser 0x5 matrix converter. The main advantages of a simplified connection are, beside smaller auxiliary converter sizing, also possible better efficiency of the HEV powertrain. So, powertrain operation in autonomous traction accu-battery modes uses direct 0x5 configuration of traction 3x5 MxC matrix converter, and in hybrid modes of Internal Combustion Engine (ICE) and accu-battery uses besides traction 3x5 MxC matrix converter the auxiliary 0x5 matrix converter. Modeling and simulation using Matlab-Simulink environment of traction powertrain configuration in autonomous modes are presented in the paper as well as all simulation experiment result
Multiphase induction motor drives - a technology status review
The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operatio
Small-Signal Modelling and Analysis of Doubly-Fed Induction Generators in Wind Power Applications
The worldwide demand for more diverse and greener energy supply has had a significant
impact on the development of wind energy in the last decades. From 2 GW in 1990,
the global installed capacity has now reached about 100 GW and is estimated to grow to
1000 GW by 2025. As wind power penetration increases, it is important to investigate its
effect on the power system. Among the various technologies available for wind energy
conversion, the doubly-fed induction generator (DFIG) is one of the preferred solutions
because it offers the advantages of reduced mechanical stress and optimised power capture
thanks to variable speed operation. This work presents the small-signal modelling and
analysis of the DFIG for power system stability studies.
This thesis starts by reviewing the mathematical models of wind turbines with DFIG
convenient for power system studies. Different approaches proposed in the literature for
the modelling of the turbine, drive-train, generator, rotor converter and external power
system are discussed. It is shown that the flexibility of the drive train should be represented
by a two-mass model in the presence of a gearbox.
In the analysis part, the steady-state behaviour of the DFIG is examined. Comparison
is made with the conventional synchronous generators (SG) and squirrel-cage induction
generators to highlight the differences between the machines. The initialisation of the
DFIG dynamic variables and other operating quantities is then discussed. Various methods
are briefly reviewed and a step-by-step procedure is suggested to avoid the iterative
computations in initial condition mentioned in the literature.
The dynamical behaviour of the DFIG is studied with eigenvalue analysis. Modal
analysis is performed for both open-loop and closed-loop situations. The effect of parameters
and operating point variations on small signal stability is observed. For the
open-loop DFIG, conditions on machine parameters are obtained to ensure stability of
the system. For the closed-loop DFIG, it is shown that the generator electrical transients
may be neglected once the converter controls are properly tuned. A tuning procedure is
proposed and conditions on proportional gains are obtained for stable electrical dynamics. Finally, small-signal analysis of a multi-machine system with both SG and DFIG is
performed. It is shown that there is no common mode to the two types of generators.
The result confirms that the DFIG does not introduce negative damping to the system,
however it is also shown that the overall effect of the DFIG on the power system stability
depends on several structural factors and a general statement as to whether it improves or
detriorates the oscillatory stability of a system can not be made
Guidelines for Weighting Factors Adjustment in Finite State Model Predictive Control of Power Converters and Drives
INTERNATIONAL CONFERENCE ON INDUSTRIAL TECHNOLOGY () (.2009.VICTORIA, AUSTRALIA)Model Predictive Control with a finite control set has
emerged as a promising control tool for power converters and
drives. One of the major advantages is the possibility to control
several system variables with a single control law, by including
them with appropriate weighting factors. However, at the present
state of the art, these coefficients are determined empirically.
There is no analytical or numerical method proposed yet to obtain
an optimal solution. In addition, the empirical method is not
always straightforward, and no procedures have been reported.
This paper presents a first approach to a set of guidelines
that reduce the uncertainty of this process. First a classification
of different types of cost functions and weighting factors is
presented. Then the different steps of the empirical process are
explained. Finally, results for several power converters and drives
applications are analyzed, which show the effectiveness of the
proposed guidelines to reach appropriate weighting factors and
control performance
Sliding modes in power electronics and motion control
In the paper the general approach to motion control systems in the sliding mode framework is discussed in details. It has been shown that, due to the fact that a motion control system with n d.o.f may be mathematically formulated in a unique way as a system composed on n 2 d.o.f systems, design of such a system may be formulated in a unique way as a requirement that the generalized coordinates must satisfy certain algebraic constrain. Such a formulation leads naturally to sliding mode methods to be applied where sliding mode manifolds are selected to coincide with desired constraints on the generalized coordinates. In addition to the above problem the design of full observer for IM based drive is discussed
Predictive control in matrix converters. Part I, Principles, topologies and applications
This paper presents an overview of the predictive control principles applied to matrix converters and also the different topologies where this control technique is applied. It will be shown that the predictive strategy is a promising alternative to control matrix converters due to its simplicity and flexibility to include additional aspects in the control being suitable for different industrial applications
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