Parameter Deviation Effect Study of the Power Generation Unit on a Doubly-Fed Induction Machine-based Shipboard Propulsion System

To lower the difficulty of fault protection,a doubly-fed induction machine based shipboard propulsion system(DFIM-SPS)that is partially power decoupled is presented.In such an intrinsically safe SPS architecture,a synchronous generator(SG)is employed for power generation,and the accuracy of the parameters of power generation unit(PGU)plays an important role in SPS stable operation.In this paper,the PGU parameter deviations are studied to evaluate the effects on system performance.The models of salient-pole SG,type DC1A excitation system(EXS)and DFIM are illustrated first.Besides,the corresponding control scheme is explained.For the 16 important parameters of PGU,up to 40%of parameter deviations are applied to implement parameter sensitivity analysis.Then,simulation studies are carried out to evaluate the parameter deviation effects on system performance in detail.By defining three parameter deviation effect indicators(PDEIs),the effects on the PGU output variables,which are the terminal voltage and output active power,are studied.Moreover,the increasing rates of PDEIs with different degrees of parameter deviations for the key parameters are analyzed.Furthermore,the overall system performance is investigated for the two most influential PGU parameters.This paper provides some vital clues on SG and EXS parameter identification for DFIM-SPS.

Performance Analysis of Nested-loop Secondary Linear Doubly-fed Machine Considering End Effects

Nested-loop secondary linear doubly-fed machine(NLS-LDFM) is a novel linear machine evolved from rotary brushless doubly-fed induction machine, which has a good application prospect in linear metro. In order to analyze the performance of NLS-LDFM, the mechanism and action rules of end effects are investigated in this paper. Firstly, the mechanism of static and dynamic end effects is analyzed in aspect of direct coupling, winding asymmetry and transient secondary current. Furthermore, based on the winding theory for short primary linear machines, the machine parameters are established qualitatively considering pulsating magnetic field of NLS-LDFM. Finally, the NLS-LDFM performance analysis is supplemented by the finite element algorithm(FEA) simulation and experiments under different operating conditions.

Brushless Doubly-Fed Induction Machine as a Variable Frequency Transformer

VFT （variable frequency transformer） has been recently used as art alternative to HVDC （high voltage direct current） to control power flow between asynchronous networks. VFT consumes less reactive power than a back-to-back HVDC system, provides faster initial transient recovery, and has better natural damping capability. VFT is simply a DFIM （doubly-fed induction machine） where the machine torque controls the power flow from stator to rotor and vice versa. The main disadvantage of this VFT is the slip rings and brushes required for the rotor circuit, especially in bulk power transmission. The BDFM （brushless doubly-fed machine） with nested cage rotor machine is proved to be a comparable alternative to conventional DFIM in many applications with the advantage that all windings being in the stator frame with fixed output terminals. In this paper, the BDFM is used as a BVFT （brushless variable frequency transformer）. A prototype machine is designed and simulated to verify the system validity.

Brushless Doubly-Fed Machines:Opportunities and Challenges

The brushless doubly-fed machine(BDFM)is a family of multiport electric machines with two ac electrical ports and a common mechanical port.Different from the conventional singly-fed machines whose synchronous speed is solely determined by a single supply frequency and the actual pole pair number,the BDFM has two supply frequencies and two different pole pair numbers to control the rotor speed.By the two accessible electrical ports,all BDFMs are endowed with more degrees of freedom for speed and power control,inherent fault-tolerant capability and high reliability.The BDFM in its broad sense has been extensively investigated as a promising alternative to the conventional slip-ring doubly-fed induction machine(DFIM)during the past decades,for both limited and wide speed range applications.This paper presents a new theoretical framework of the BDFM within which all topological variants can be closely linked by the similarities in working principle.The individualities of each machine topology are presented first,followed by the commonalities such as the modeling techniques,modes of operation,design considerations and control strategies.The challenges are identified and highlighted based on recent developments and possible opportunities are predicted considering the unique nature of this special AC machine type.

Design and analysis of a dual-stator brushless doubly-fed induction machine with a staggered dual-cage rotor

In this paper,a new dual-stator brushless doubly-fed induction machine with a staggered dual cage rotor is proposed,with emphasis on the general interconnection rule of the conductor bars for the staggered dual cage rotor.Since the squirrel cage rotor offers the merits of robustness,reliable structure,high slot filling factor,and low rotor resistance comparing to the wound rotor,it is introduced to the dual-stator brushless doubly-fed induction machine to solve the problems of high copper loss and unreliable rotor structure for the dual-stator brushless doubly-fed induction machine with a wound rotor.The originality of this article is to investigate the interconnection rule of conductor bars between the inner and outer cages.The constraint condition that is supposed to be satisfied is deduced by using the rotating magneto-motive force theory,based on which diverse slot/pole combinations are investigated.The performance comparison between the existing and proposed machines is conducted.Finally,a prototype is designed and fabricated.The experimental results verify the effectiveness of the proposed topology.

Overview of Research and Development Status of Brushless Doubly-Fed Machine System

The brushless doubly-fed machine(BDFM)has been widely used due to its advantages of robustness,reliable operation,ease of maintenance,adjustable power factor,small converter capacity and low cost.BDFM is attractive for use in many applications such as variable frequency speed regulation systems and variable speed constant frequency generation systems.Hence,there is a rapidly growing interest in design and control of BDFM.In this paper,the origin and development of BDFM are reviewed,the structural characteristics of BDFM are discussed at length,the principles of operation and design are analyzed,and the different control methods used for BDFM are overviewed and compared in detail.Finally,challenges and opportunities of BDFM are concluded.

无刷双馈电机工作原理和数学模型的研究

无刷双馈电机作为一种新型的交流调速电机,在风力发电和水力发电中都有很好的发展前景。本文介绍了该电机的工作原理,分析了该电机的两种数学模型-三相静止坐标系中的数学模型和d-q坐标系中的数学模型,并在d-q坐标系数学模型基础上搭建BDFM的Matlab/Simulink动态仿真模型,通过一系列的仿真验证了数学模型的正确性,为以后对该种电机进行深入的研究奠定了基础。