Surface-mounted Permanent Magnet Synchronous Generator Research Articles

A Thorough Procedure to Design Surface-Mounted Permanent Magnet Synchronous Generators

This paper sets forth a thorough procedure to design surface-mounted permanent magnet synchronous generators. Since synchronous generators generate the majority of electrical energy, their relevance in society nowadays is substantial. As a consequence, the methodology to design these electrical machines also holds great importance. However, even though a considerable amount of works addresses the matter, it is difficult to find a complete and thoroughly explained design procedure. The proposed method is based on analytical equations to fully consider PM generator fundamentals with a few simplifications, which implies in a considerable number of design equations and parameters. Differently from most papers on the design of PM synchronous generators, a significant level of detail and explanation is presented, all design choices are discussed, and the suggested ranges for the design parameters are shown. This results in a straightforward procedure that allows non-experienced designers to easily replicate the results and effectively enhance the comprehension of permanent magnet synchronous machines, and provides a guideline for researchers from other fields who may need to understand and perform a synchronous generator design. To show the effectiveness of the proposed design procedure, a PM generator is designed, and the results are compared with a finite element simulation, showing good accuracy.

Virtual inertia support based frequency and dynamic voltage control for grid-connected SPMSG-based wind turbine

The Challenge to stabilize the grid frequency increases with the increment of renewable energy resources. System inertia/frequency control is a significant concern for maintaining system stability with a fast response time during the load transition. This manuscript proposes surface-mounted permanent magnet synchronous generator (SPMSG) based wind energy conversion system (WECS) with a frequency support DC-link controlling loop and a converter protective DC-link voltage-controller frequency support system. To achieve power exchange, the frequency control system (FCS) for the SPMSG-based wind turbine supports the grid-side virtual inertia. The DC-link voltage is disturbed during the load transition to maintain the frequency, while the electrolytic capacitor requires extra care regarding the DC bus voltage. This manuscript incorporates the FCS system with a supercapacitor and dynamic voltage limiter to avoid additional care of the DC bus voltage. A detailed analysis of system frequency with the additional load increment, normal connected load decrement, and various fault scenarios has been done. The proposed system is compared with the existing virtual inertia support (VIS). The simulation results show that the proposed frequency control system-based VIS efficiently limits the frequency deviations & DC-link voltage. The results are verified in the OPAL-RT 4510 real-time simulator environment to ensure the efficacy of the proposed system.

Demagnetization effects of surface-mounted permanent magnet synchronous wind generator

To prevent fossil resources from being depleted and protect the natural balance, renewable resources come to the forefront as an alternative to fossil resources. Wind energy resources, among the renewable energy resources, are important in terms of ensuring the reliability of energy and the use of their resources. Generators are the most important components for the conversion of wind power. Permanent magnet synchronous generators (PMSGs) are preferred in wind turbines since they have high efficiency and high volume/torque densities, thereby optimization of the PMSGs is an important topic for the wind energy community. On the one hand, these machines can cause problems due to overheating and mechanical friction during their long-time operation. To identify the performance lack of the machines due to the de-magnetization faults, systematic work has been performed. When a magnet of a PMSG is de-magnetized at different rates (i.e. 33%, 50%, and 100%), we have explored the artifacts in the electric generation. Besides, the torque performances of the generator at rated load are examined and the flux density distributions are revealed. The rated torque decreased substantially when the demagnetization rate of the magnet increased.

Design and Analysis of a Variable-Speed Constant-Amplitude Wind Generator for Stand-Alone DC Power Applications

This paper presents the design and analysis of a permanent magnet (PM) wind generator which consists of two sets of windings, and two rotors. The proposed PM wind generator is designed for variable-speed constant-amplitude voltage operation in DC power applications, in order to maximize the utilization of wind energy and make the electricity more accessible to stand-alone situations, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e.g.</i> , remote areas and offshore islands. The operating principle of the variable-speed constant-amplitude voltage operation of the proposed PM wind generator is demonstrated in detail. A comparative study is carried out among the proposed generator, a conventional surface-mounted PM synchronous generator, and an existing counterpart generator used for the same application. The results show that compared to the conventional PM synchronous generator and the existing counterpart, the proposed PM wind generator exhibits the advantages of high induced voltage, high torque/power density, high efficiency, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">etc.</i> Finally, the proposed PM wind generator is prototyped and manufactured. The validity of the variable-speed constant-amplitude operation of the proposed generator under both steady-state and dynamic conditions, is verified by experimental results.

Design and Implementation of Predictive Controllers for a 36-Slot 12-Pole Outer-Rotor SPMSM/SPMSG System with Energy Recovery

This paper investigates a drive system with energy recovery which uses a 3-phase 1-kW 36-slot 12-pole distributed winding outer-rotor surface-mounted permanent-magnet synchronous motor (SPMSM) and surface-mounted permanent-magnet synchronous generator (SPMSG), which can be used in indoor exercise bicycles. In order to extend drive system operating speed range, the constant torque control, flux-weakening control, and maximum torque/voltage control are used to extend its operation speed up to 1.75 times rated speed. In addition, a predictive speed controller and a predictive current controller are proposed to improve transient responses, load disturbance responses, and tracking responses. A digital signal processor, type TMS-320F-28035, manufactured by Texas Instruments, is used as a control center for the proposed SPMSM/SPMSG drive system. Experimental results validate the feasibility and correctness of the proposed methods.

Direct Power Control of a Surface-Mounted Permanent Magnet Synchronous Generator Wind Turbine for Offshore Applications

This paper proposes a direct power control scheme for an offshore wind turbine-driven surface-mounted permanent magnet synchronous generator with a full back-to-back converter situated onshore to decentralize the weight of the turbine. The proposed model is designed in a stationary reference frame and does not require a phase-locked loop as opposed to the traditional vector current control method. Simple feed-forward and feedback control loops are used in the proposed model to extract the maximum available wind power, maintain constant voltage at the coupling DC link, and ensure power injection into the electric network at unity power factor. Simulation results carried out in MATLAB/SIMULINK show that the proposed model has fast transient response and steady-state performance consistent with the vector current control model. Furthermore, eigenvalue analysis results demonstrate that the proposed method’s performance is robust to variations in different system parasitic elements, even under both stiff and weak electric network conditions. These results also indicate that the back-to-back converter can operate effectively when located onshore close to the load center, while the turbine is in close proximity offshore. This can be suitable for multiple specific offshore applications as it has the potential to reduce the overall weight, volume, and cost of the offshore wind turbine infrastructure.

A SDTOGI based speed control method for SPMSG in WECS

Abstract The sensorless techniques are incorporated to optimize the cost and performance of the Surface Mounted Permanent Magnet Synchronous Generator (SPMSG) in the Wind Energy Conversion System (WECS) in this manuscript. Strengthen Dual third-Order Generalized Integrator (SDTOGI) with Synchronous Reference Frame-Phase Locked Loop (SRF-PLL) is applied in SPMSG to estimate the speed &amp; position of the measured generator stator current. The proposed technique is applied in low-speed direct-driven 1.5 MW SPMSG. SDTOGI with SRF-PLL technique is compared with conventional techniques to investigate the efficacy of the proposed sensorless technique due to rapid change in the torque of the turbine. The stability of the proposed system is higher, as shown in the Nyquist plot. Further, the obtained simulation result shows that the proposed method estimates position and speed efficiently. The results are verified in the OPAL-RT 4510 real-time simulator environment to ensure the efficacy of the proposed technique.

Online Detection and Location of Eccentricity Fault in PMSG With External Magnetic Sensing

The detection and location of eccentricity faults in a permanent magnet synchronous generator (PMSG) become increasingly essential, especially in safety-critical applications. However, the existing approaches for monitoring eccentricity subject to many limitations. In this article, a novel method for online detection and location of the eccentricity fault in a PMSG is proposed based on the external magnetic sensing. The noninvasiveness facilitates installation and maintenance work. In this article, the effect of different eccentricity faults on the external leakage flux density is analyzed theoretically with the magnetic equivalent circuit method first. Then, two indicators are proposed for detecting static eccentricity (SE) and dynamic eccentricity (DE), respectively. The amplitudes of the SE and DE indicators are proportional to the fault degree. The angle of the SE indicator proves to be the direction of SE. Meanwhile, two indicators show excellent robustness and are independent of loads and rotation speed. Moreover, these indicators can be applied in any surface-mounted PMSG with a three-multiple number of slots. Accordingly, an algorithm to diagnose the eccentricity fault is shown based on two indicators from three sensing points outside. The computation of the method is light, which leads to fast detection speed. Finally, the accurate results in multioperating conditions from simulations and experiments verify the feasibility of the proposed approach.

Model predictive control of direct-driven surface-mounted permanent magnet synchronous generator based on active disturbance rejection controller

PurposeThis paper aims to mainly discuss how to suppress the disturbances accurately and effectively in the wind energy conversion system (WECS) of the direct drive surface mount permanent magnet synchronous generator (SPMSG).Design/methodology/approachThe disturbances in wind energy conversion system have seriously negative influence on the maximum power tracking performance. Therefore, a model predictive control (MPC) method of model compensation active disturbance rejection control (ADRC) strategy in parallel connection is designed, which optimizes the speed tracking performance compared with the existing control strategy of MPC and ADRC in series connection. Based on the traditional ADRC, a multi parameter model compensation ADRC strategy is added to better estimate the disturbances. At the same time, a torque feedback strategy is added to compensate the disturbances caused by load torque and further optimize the speed loop tracking performance.FindingsThe simulation results show that the designed control method has advantages than the traditional control method in compensating the disturbances and tracking the maximum power more effectively.Originality/valueThe simulation results show that the designed control method is superior to the traditional proportional control method, which can better compensate the internal and external disturbances and track the maximum power more effectively.

An Improvement on Slot Configuration Structure of a Low-Speed Surface-Mounted Permanent Magnet Synchronous Generator with a Wound Cable Winding

This paper are concentrated on low-speed surface-mounted permanent magnet synchronous generator (LS-SMPMSG) electromagnetic design using finite-element (FEM)-based method. Introduced LS-SMPMSG as an important generator in the industry is utilized in marine energy conversion (MEC) and tidal energy conversion (TEC) systems. The main feature of the designed LS-SMPMSG exhibited is its ability to generate electrical power in MEC and TEC systems at a low speed of approximatively 100 rpm. In this paper, a new slot structure for LS-SMPMSG has been proposed to enhance the LS-SMPMSG performance. The FEM analysis and comparing results shows that the new slot structure reduced the torque ripple and the cogging torque equal to 19.54% and 87.5%. respectively. Also, it influenced the LS-SMPMSG Joule losses by reducing it close to 16.1%. Another advantage of the new slot structure of LS-SMPMSG is its easy construction and assembly. The FEM analysis as a powerful method validates the advantages of the proposed structure.

Composite control for disturbed direct-driven surface-mounted permanent magnet synchronous generator with model prediction strategy

In order to obtain the best power in the wind energy conversion system (WECS) of the direct-driven surface-mounted permanent magnet synchronous generator (SPMSG), active disturbance rejection control (ADRC) is introduced to track the motor speed in real time. The control algorithm provides a new design concept and an inherent robust controller component that requires very little system information. Aiming at the problem of system parameter mutation caused by internal factors and external environment changes, an adaptive controller with multi parameter identification is designed, and the disturbance caused by parameter changes is compensated in real time. The model predictive current control (MPC) technology for the sudden change of external environment is designed to accelerate the response speed of the current loop, so as to weaken the estimation of the current disturbance by the active disturbance rejection controller, and make the speed estimation more accurate. Simulation results show that the proposed control strategy is effective and satisfactory.

New Adaptive Control Strategy for a Wind Turbine Permanent Magnet Synchronous Generator (PMSG)

Wind energy conversion systems have become a key technology to harvest wind energy worldwide. In permanent magnet synchronous generator-based wind turbine systems, the rotor position is needed for variable speed control and it uses an encoder or a speed sensor. However, these sensors lead to some obstacles, such as additional weight and cost, increased noise, complexity and reliability issues. For these reasons, the development of new sensorless control methods has become critically important for wind turbine generators. This paper aims to develop a new sensorless and adaptive control method for a surface-mounted permanent magnet synchronous generator. The proposed method includes a new model reference adaptive system, which is used to estimate the rotor position and speed as an observer. Adaptive control is implemented in the pulse-width modulated current source converter. In the conventional model reference adaptive system, the proportional-integral controller is used in the adaptation mechanism. Moreover, the proportional-integral controller is generally tuned by the trial and error method, which is tedious and inaccurate. In contrast, the proposed method is based on model predictive control which eliminates the use of speed and position sensors and also improves the performance of model reference adaptive control systems. In this paper, the proposed predictive controller is modelled in MATLAB/SIMULINK and validated experimentally on a 6-kW wind turbine generator. Test results prove the effectiveness of the control strategy in terms of energy efficiency and dynamical adaptation to the wind turbine operational conditions. The experimental results also show that the control method has good dynamic response to parameter variations and external disturbances. Therefore, the developed technique will help increase the uptake of permanent magnet synchronous generators and model predictive control methods in the wind power industry.

Model Reference Adaptive System with Finite-Set for Encoderless Control of PMSGs in Micro-Grid Systems

In micro-grid systems, wind turbines are essential power generation sources. The direct-driven surface-mounted permanent-magnet synchronous generators (SMPMSGs) in variable-speed wind generation systems (VS-WGSs) are promising due to their high efficiency/power density and the avoidance of using a gearbox, i.e., regular maintenance and noise are averted. Usually, the main goal of the control system for SMPMSGs is to extract the maximum available power from the wind turbine. To do so, the rotor position/speed of the SMPMSG must be known. Those signals are obtained by the help of an incremental encoder or speed transducer. However, the system reliability is remarkably reduced due to the high failure rate of these mechanical sensors. To avoid this problem, this paper presents a model reference adaptive system with finite-set (MRAS-FS) observer for encoderless control of SMPMSGs in VS-WGSs. The motif of the presented MRAS-FS observer is taken from the direct-model predictive control (DMPC) principle, where a certain number of rotor position angles are utilized to estimate the stator flux of the SMPMSG. Subsequently, a new optimization criterion (also called quality or cost function) is formulated to select the best rotor position angle based on minimizing the error between the estimated and reference value of the stator flux. Accordingly, the traditional fixed-gain proportional-integral regulator generally employed in the classical MRAS observers is not needed. The proposed MRAS-FS observer is validated experimentally, and its estimation response has been compared with the conventional MRAS observer under different conditions. In addition to that, the robustness of the MRAS-FS observer is tested at mismatches in the parameters of the SMPMSG.

Controllable single-phase smart synchronous generator towards solar-pneumatic power generation

This paper presents the development of a controllable single-phase surface-mounted permanent magnet synchronous generator (SPSMPMSG) for low speed applications. Presently, the world is faced with degrading climatic conditions that may be worsen if energy need is met by fossil fuel and other conventional means of generation. On the other hand, renewable alternatives are not always of constant speed, and are usually not high enough to turn conventional alternators. There is therefore a need for the development of alternators that can generate electricity from low speed sources. The development of permanent magnet from rare-earth materials has revolutionized the electrical generator development. Permanent magnet machines are characterized by high torque, low noise, high efficiency and high power factor. The use of these magnets also made it possible to add computer based controllability making the generator a smart machine. This paper presents a CAD design of smart generator at an input speed of 500rpm to a turbine to produce a constant output of 220V. Simulation and physical test results produce an output of 220V ± 1% and give a clear indication that low speed renewable energy sources can produce usable electrical power.&#x0D; Keywords: Smart generator, Permanent magnet generator, stator, rotor, Computer-aided design.

Wind-Speed Estimation and Sensorless Control for SPMSG-Based WECS Using LMI-Based SMC

To enhance system reliability and to reduce the cost and complexity, this paper presents an efficient wind-speed estimation method and a sensorless rotor-position/speed control method for a surface-mounted permanent-magnet synchronous generator (SPMSG)-based variable-speed direct-drive wind-energy conversion system (WECS). In this regard, sliding mode control (SMC) based on a linear matrix inequality (LMI) is proposed to estimate the rotor position of an SPMSG. This method depends on measured electrical quantities, such as stator voltages and estimated stator current error, to evaluate the back electromotive force components, which are used to estimate the rotor position. The rotor speed is assessed according to the rate of change of the estimated rotor position. The wind speed is estimated by estimating the backpropagation power flow according to the nonlinear dynamical power wind-speed characteristics of the wind turbine. In estimating the rotor position, the proposed LMI-based SMC design provides good steady-state and dynamic performances under all operating modes of the WECS. The proposed control schemes are validated by simulating a test system, i.e., a 250-kW SPMSG-based WECS, in MATLAB/Simulink. The results confirm the effectiveness and correctness of the designed control schemes in estimating and tracking the actual rotor position/speed and wind speed with trivial errors.

Parameters evaluation of a permanent magnet synchronous generator with modular stator

This paper presents the evaluation of the parameters of a surface-mounted permanent magnet synchronous generator designed for wind generation in urban areas, and manufactured in a ring shaped around the turbine with modular stator. In the project, the analytical subdomain method and finite element analysis provides the inductances, both in two dimensions, and compared with experimental results in order to quantify the end winding leakage inductance. The analytic and numeric results indicate a reduction of inductances with increases of slots per winding phase. The experimental measurement allows identify the end winding leakage inductance that, due to the unconventional dimension proportions, is approximately 30% of total.

Non‐linear vector current source for the control of permanent magnet synchronous generators in wave energy applications

A current source with a space-vector hysteresis band and a constant switching frequency has been designed to be used with surface-mounted permanent magnet synchronous generators. Its fast response makes it very suitable to carry out the precise control necessary in wave energy converters (WEC). These systems are characterised by large variations of speed, torque (or force) and frequency which means that the control has to cope with large variations of voltage and current and also with persistent periods where these variables present low values. The control system takes into account both rotation direction (or displacement direction, when a linear generator is considered) and electrical sequences, something necessary in WEC such as point absorbers. The algorithm was successfully tested in the laboratory using an ad hoc built emulator, that reproduces the behaviour of an oscillating water-column-based WEC. The emulator was built using a similar hardware to those used in equivalent real systems.

Digital Controller Design via LMIs for Direct-Driven Surface Mounted PMSG-Based Wind Energy Conversion System.

The main concern of this paper is to design the efficient sampled-data controller scheme that resolves the stabilization issue of a surface-mounted permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS). Distinct to the existing controller schemes on WECS, the present scheme contains both continuous (plant) and discrete (control) type of signals which outperforms the traditional scheme with continuous or discrete signals. Besides that the fundamental analysis of the closed-loop system under the designed controllers explore the dynamical characteristics of the considered PMSG-based WECS. The stability and stabilization of the proposed closed-loop system have guaranteed through the Lyapunov stability theory and solvable linear matrix inequalities (LMIs). In detail, first, the nonlinear PMSG model has equivalently expressed into linear submodels via the Takagi-Sugeno (T-S) fuzzy approach based on suitable membership rules. Second, the sufficient conditions have been derived as LMIs that ensure the stability and stabilization of the formulated T-S fuzzy PMSG-based WECS. Finally, the effectiveness of the designed controller as well as the consistency of sufficient conditions has demonstrated through numerical evaluations of the closed-loop system.

Efficient Direct-Model Predictive Control With Discrete-Time Integral Action for PMSGs

This paper presents an efficient direct-model predictive control (EDMPC) technique for surface-mounted permanent-magnet synchronous generators (PMSGs) in variable-speed wind energy conversion systems. The proposed control technique is based on directly computing the reference voltage vector (VV) from the demanded currents using a deadbeat (DB) function. Then, a discrete-time integral action (DTIA) is added to this DB function to enhance the robustness of the proposed EDMPC scheme against variations of the machine parameters and to achieve a good steady-state response. The proposed DTIA is simple and easy to implement. Finally, according to the location of this reference VV, two evaluations of the quality function are only required. Accordingly, the proposed EDMPC technique with DTIA overcomes the following drawbacks of the conventional direct-model predictive control (DMPC): high calculation burden, sensitivity to parameters mismatches, and non-zero steady-state error. The performance of the proposed EDMPC technique with DTIA has been experimentally investigated and compared with that of the EDMPC with time delay control approach and with the performance of the convention DMPC using a $\text{14.5}\,\text{kW}$ PMSG.

Full operational regimes for SPMSG-based WECS using generation of active current references

The intermittency of wind speed poses challenges to obtaining reliable power and integrating wind plants successfully with existing power infrastructure. Fast and efficient controls are required to cater to the transient nature of wind speed and simplify wind power control. This paper presents an efficient control mechanism for operating a wind energy conversion system (WECS) over its full operating range by incorporating a surface-mounted permanent magnet synchronous generator (SPMSG) to generate suitable active current references based on generator voltage and achieve the maximum power output from a wind turbine. In the partial-load state, the control scheme operates based on field-oriented control with a maximum power point tracking controller to maximize the energy harvested from the wind. In the full-load operating regime, the control swings towards maximum electrical torque by invoking a feedback-based flux-weakening strategy with voltage and current constraints. Furthermore, a nonlinear pitch angle controller is employed to ensure normal operation at high wind speeds. The proposed scheme is intended for a variable-speed variable-pitch WECS based on a direct-drive SPMSG for both underrated and overrated wind speeds, and can be connected to the utility grid. The validity and effectiveness of the proposed scheme are verified through numerical simulations performed on a 2.41 MW WECS. The results confirm the scheme’s ability to cope with WECS dynamics within safe operating limits.