Doubly-fed Machine Research Articles

Design and Performance Analysis of Brushless Doubly-Fed Machine for Wind Power Generation Using AI

Design and Performance Analysis of Brushless Doubly-Fed Machine for Wind Power Generation Using AI

Torque Ripple Suppression in Three-Phase Doubly-Fed Machine for Wireless Power Transfer in Integrated Drives

Torque Ripple Suppression in Three-Phase Doubly-Fed Machine for Wireless Power Transfer in Integrated Drives

Investigation of Cascaded and Modulated Rotors for Dual-Stator Brushless Doubly-Fed Machines

Investigation of Cascaded and Modulated Rotors for Dual-Stator Brushless Doubly-Fed Machines

Derivation of Equivalent Circuit Rotor Current from Rotor Bar Current Measurements in Brushless Doubly-Fed Machine

Derivation of Equivalent Circuit Rotor Current from Rotor Bar Current Measurements in Brushless Doubly-Fed Machine

Design and Implementation of Novel Rotor Side Brushless Controller With Bidirectional Wireless Power Transmission for Doubly-Fed Machine

This paper proposes a novel rotor side brushless controller (RSBC) with bidirectional wireless power transmission (WPT) for a doubly-fed motor (DFM), which can realize the brushless DFM without changing the stator and rotor structures. The WPT-RSBC consists of a grid side converter, a series–series compensated resonant converter, and a rotor side converter. According to the operational characteristics of DFMs, the design requirements of the WPT-RSBC are given in this paper. The systematic selection method for four-quadrant operations of the DFM is introduced, and the variable bus voltage control strategy is proposed to improve its transmission efficiency. The mathematical model and small-signal model of each subsystem in the WPT-RSBC are given, and the stability of the primary and secondary DC bus is analyzed. An experimental platform is implemented to verify the feasibility of the WPT-RSBC. For the prototype, the air-gap length is 1 mm, and the RSBC's transmission efficiency can be up to 92%.

Generalized High-Fidelity Reduced-Order Model of Doubly-Fed Machines and Induction Machines

Generalized High-Fidelity Reduced-Order Model of Doubly-Fed Machines and Induction Machines

Design of a Wound Rotor Brushless Doubly-Fed Machine With 1/5 Pole-Pair Combination

The brushless doubly-fed machine (BDFM) can be used in the variable speed constant frequency field. For BDFM, the choice of the pole-pair combination and the design of the rotor are significant. The output factor of the BDFM with 1/5 pole-pair combination is higher than that of the 2/4 pole-pair counterpart. However, the rotor of the BDFM with 1/5 pole-pair combination is hard to design for its wide pole-pair ratio. This paper presents a 1/5 pole-pair combination BDFM used in hydro power with a three-phase symmetrical wound rotor to solve the design challenge. First, the magnetic field modulation theory of the BDFM and the optimal output power in terms of different pole-pair combinations are introduced. Then, the slot-number phase diagram and the ampere-conductor wave method are applied to design windings of a BDFM with 1/5 pole-pair combination. Finally, the finite element (FE) models of the 1/5 and the 2/4 pole-pair combination BDFMs are established for comparison. A prototype of the 1/5 pole-pair combination is manufactured based on the proposed design scheme. Simulated and experimental results verified the feasibility of the design scheme.

Sliding mode control of brushless doubly-fed machine used in wind energy conversion system

This paper presents the applications of the sliding mode control to a brushless doubly fed induction generator (BDFG) used in wind-energy conversion systems. The controller is designed based on the sliding mode control combined with a the stator power winding flux oriented vector principle, the independent control of active and reactive powers has been developed and the performance of proposed the block diagram of the variable speed constant-frequency (VSCF) wind energy generation system is validated in the Matlab/Simulink environment and the computer simulation results obtained confirm the effectiveness of this control strategy.

Rotor Winding Design and Standalone Operation Research of High Natural Synchronous Speed Brushless Doubly-Fed Generator Based on Differential Modulation

Differential Modulation Brushless Doubly-fed Machine (DMBDFM) can achieve smaller equivalent pole-pair number, which broaden the operating range and application of Brushless Doubly-fed Machine (BDFM). However, the existing basic theory of BDFM can not be directly applied to DMBDFM, and the design method of the modulated rotor with different combination of pole-pair numbers (PPN) is not complete. Therefore, in order to achieve the highest natural synchronous speed(<i>n</i>_s) of BDFM at power system frequency, the rotor winding of 3&#x002F;2 pole pairs is designed in this paper. Then the test prototype is developed with the designed rotor scheme and the relevant parameters are given. The validity of the rotor design scheme is verified by finite element simulation and test results.

Research and Analysis of the Characteristics of the Brushless Doubly-Fed Machine with High-Performance Decoupling Control

The paper presents the state-space (SS) model of the brushless double-fed machine (BDFM) by taking the negative conjugate (NC) transformation of the power machine’s correlation variable when the current source of the control machine is supplied in the m-t reference frame. Based on this, the testing method of machine parameters is given, and the SS model described by five parameters is obtained. The derivation process and realization method of the slip-frequency vector feedback linearization control (SFV-FLC) strategy are given. Then, researching the SS equation in the m-t reference frame by the control machine rotor field-oriented, the relationship between the maximum and minimum output torque and the control machine rotor flux amplitude and slip velocity, the machine parameters are given considering power supply constraints. Finally, the validity of the theoretical analysis is verified by simulation and experiment, and the feasibility of the decoupling control method are also demonstrated.

Design of a Brushless Doubly-Fed Machine for Aviation Electric Propulsion

This article discusses a high-speed brushless doubly-fed machine (BDFM) for aviation turboelectric distributed propulsion application. After a brief overview of the machine fundamentals and propulsion architecture, the electromagnetic properties of the newly designed BDFM are analyzed. An innovative rotor mechanical design is introduced, which allows for a significant increase of speed compared to legacy rotor designs. Experiments were conducted to verify the 12 000-r/min high-speed operation. The findings in this article will give prominence to the feasibility of applying BDFMs for aviation applications.

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.

Speed sensorless direct voltage control of brushless doubly-fed machine independent generation system based on improved particle swarm optimization algorithm

The speed information is obtained by sensors in the control strategy of brushless doubly-fed machine (BDFM) independent power generation system. However, the use of sensors increases the hardware cost of the system, reduces the reliability and the sensors are difficult to adapt to the harsh environment such as high temperature and high humidity. In order to solve the above problems, a speed sensorless direct voltage control method for brushless doubly-fed machine independent generation system is proposed. At the same time, in order to improve the control quality, the improved particle swarm optimization algorithm is used to optimize the control parameters of the system. Simulation results show that the BDFM independent power generation system can still maintain excellent performance and can meet the performance requirements in various operating conditions with the control method proposed in this paper.

Hierarchical frequency control strategy of doubly-fed induction diesel generator under emergency condition

Natural disasters lead to the uncertain topological structure of the urban distribution network. It is difficult for the communication system to recover quickly, which brings great difficulties to restoring the power supply. Therefore, the deployment of an emergency power supply is one of the critical measures to ensure the stable operation of isolated network systems and reduce power loss. Compared with the traditional synchronous diesel generator (SDG) as an emergency power supply, a doubly-fed induction diesel generator (DFIDG) has the advantages of flexible and controllable, rapid response and high operation efficiency. This paper presents a layered frequency control strategy for a doubly-fed induction diesel generator in an emergency scenario. Firstly, the models of doubly-fed induction diesel generator and its control system, prime mover and its speed regulation system are established. Secondly, the hierarchical frequency control strategy is proposed, including primary integrated frequency control (including droop control and virtual inertia control) and secondary frequency regulation control based on translation method. The virtual inertia control can make the doubly-fed machine quickly release the rotor kinetic energy when the frequency changes rapidly, so as to improve the frequency supportability. According to the overall shortage of the system and the maximum output power of the doubly-fed induction diesel generator, the strategy calculates the secondary frequency regulation power adjustment as the DFIDG power setting value, and then can realize automatic secondary frequency regulation without a communication system. Finally, simulation results verify the effectiveness of the proposed strategy.

Impedance modeling of wind turbine-variable speed pumped storage combined operation system

In the combined operation system of variable speed pumped storage and direct drive wind turbine, multiple power electronic devices are coupled with each other, and the operating conditions are complex, it is necessary to conduct deep research on the stability of the system. In the synchronously rotating coordinate d-q-0 system, this paper introduces the speed of the doubly-fed machine as a variable, and adds the small signal model of the pump turbine, and establishes a joint operation system suitable for 0.1 Hz–200 Hz stability analysis broadband impedance model. Based on the generalized Nyquist theory, the corresponding stability analysis of the system under different working conditions and different parameters can be carried out.

Design Method of Differential Cascading for Dual-Stator Brushless Doubly-Fed Induction Wind Generator With Staggered Dual Cage Rotor

This article proposes a new differential-cascading-based dual-stator brushless doubly-fed induction machine with a staggered dual cage rotor. Conventional differential mode of the brushless doubly-fed machine with cage rotor suffers from the low number of rotor bars because of the low equivalent synchronous pole pairs of |p1-p2|, and thus, severe rotor flux leakage, low capacity of magnetic field conversion of the rotor and low efficiency. To overcome the obstacle of the excessive harmonics of the rotor, a design method based on the differential cascading is proposed which enables the cage rotor with a high number of conductor bars even in the case of low pole pairs of |p1-p2|, hence the greatly reduced rotor leakage inductance and enhanced performance of the machine. The rotating magneto-motive force theory is applied to derive the interconnection rule of the staggered dual cage rotor, and meanwhile, the corresponding examples are illustrated. The performance comparisons between the differential cascading and the sum cascading based on the proposed machine are carried out. The results show that the proposed machine based on the differential cascading obtains higher power densities comparing to the sum cascading at the region of sub-natural synchronous speed, while its drawback is the increment of the loss due to the high rotor frequency, gaining lower efficiencies at the region of super-natural synchronous speed.

Control system of induction motor drive of a hoisting unit with a controlled current converter in the rotor circuit

The use of a double-feed machine circuit is a promising way to modernize induction motor drives of mine hoisting installations. The main problem of using doubly-fed electric machine in the electric drives with a large range of speed control is the release implementation and machine operation of after it at low speed. Existing implementations of electric drives based on a doubly-fed machine (DFM) assume the use of additional resistors in the rotor circuit (rotor station) for releasing the brakes, which complicates the control circuit and significantly reduces the reliability of the drive. In this case, the electric drive circuit with additional active resistances in the rotor circuit has optimal starting characteristics, since a change in the active resistance of the rotor does not cause a change in the critical moment, and, therefore, in the overload capacity, which makes it possible to implement the release mode. It is possible to preserve the advantages of regulating the DFM speed by changing the active resistance of the rotor by using an imitation of its change. The article is devoted to the study of the possibility of implementing such mode using a controlled current converter in the rotor circuit.

A New Iron Loss Model for Brushless Doubly-Fed Machines With Hysteresis and Field Rotational Losses

The brushless doubly-fed machine (BDFM) has two stator windings with different pole numbers, supplied with different frequencies. Therefore, the distribution of magnetic fields in stator and rotor iron is complex. In addition, the stator flux density distribution is non-sinusoidal and has a DC offset at the natural speed. This makes the use of conventional hysteresis models utilised for sinusoidal fields impractical for the BDFM. In this paper a new hysteresis model is proposed for the BDFM stator iron based on the scalar Preisach model. The rotational characteristics of the magnetic fields in the BDFM are also considered and their effects in generating iron losses are assessed. 2-D time-stepping finite element (FE) models are developed for a prototype D160 BDFM to estimate iron losses and are validated by experiments.

Modeling and Simulation of Mechanical and Electrical Transient of Variable-Speed Pumped Storage Units

In order to study the operation characteristics of large capacity variable-speed pumped storage units connected to the system, the electromechanical transient model is established. Firstly, based on the basic equations of the doubly-fed machine, the generator model represented by an equivalent voltage source is built. Secondly, on the premise of coupling term cancellation, the frequency conversion controller, frequency converter and generator connection module are normalized. Then, the generator model and variable frequency controller model are integrated to form the electromechanical transient model of the unit, which is not only the fitting of external characteristics but also retains the dynamic process of the motor flux linkage and the dynamic characteristics of the controller’s inner loop. Finally, the electromechanical transient model is simulated on the RTDS platform. The simulation results show that the model is correct and effective, which is of great significance to the study of transient problems of large-capacity doubly-fed units connected to the grid.

Modeling of induction motor drive of a mine hoist on the basis of a doubly-fed electric machine

One of the options for the modernization of existing hoist electric drives with a wound-rotor induction motor is its starting according to the scheme of a doubly-fed machine. For this purpose, a frequency converter with an adjustable amplitude, frequency and phase shift of the voltage at its output is connected to the motor rotor. At the same time, the problem of obtaining a mathematical model of both the double fed machine itself and the speed control system based on it is relevant due to the need to take into account the additional supply voltage in the differential equations drawn up in accordance with the Kirchhoff’s law for the stator and rotor windings. The paper proposes a structural diagram for the mathematical model of an induction motor drive of a hoist based on a doubly fed machine.