Interior Permanent Magnet Synchronous Generator Research Articles

Beyond 15 MW: A cost of energy perspective on the next generation of drivetrain technologies for offshore wind turbines

Leading wind turbine manufacturers are racing to build larger and more powerful offshore machines. Drivetrain configurations often use a permanent-magnet synchronous generator (PMSG), in either a direct-drive configuration or coupled to a gearbox. With increasing demand for critical rare-earth magnets, new generator technologies are emerging to ensure a stable and secure supply chain. We evaluate three different topologies of radial flux synchronous generators employing high field magnets with reduced or no rare-earth content: a direct-drive interior PMSG (DD-IPMSG), a geared drivetrain combining a medium speed gearbox with a PMSG (MS-PMSG), and a direct-drive low-temperature superconducting generator (DD-LTSG). We develop a conceptual design module for each of these technologies within a larger framework for full turbine design. This provides the fairest comparison between technologies at nominal power ratings from 15–25MW, which represent the next generation of offshore wind turbines. The analyses show that if operational expenditures (OpEx) are constant across the technologies, MS-PMSG results in the lowest LCOE with reductions of up to 7% relative to DD-IPMSG. DD-LTSG also yields lower LCOE values by 2%–3% for fixed-bottom turbines and 3%–5% with a floating platform. However, results are sensitive to OpEx assumptions, with a mere 10% increase causing the conclusions to shift.

Designing of an Enhanced Fuzzy Logic Controller of an Interior Permanent Magnet Synchronous Generator under Variable Wind Speed

On account of active governmental stimulation operations in many countries, the residential production of electricity from renewable resources has increased considerably. Due to high efficiency and reliability, a recommended solution for residential wind energy conservation systems (WECS) is permanent magnet synchronous generators (PMSG). A higher torque ripple (TR), engendered by the contact of the stator with the rotor's magnetomotive force harmonics, is one foremost issue in PMSGs. To control the synchronous generator, numerous control schemes have been proposed. However, it still faces a challenge in the diminishment of the TR. An enhanced fuzzy logic controller (EFLC) in interior PMSG (IPSMG) under variable wind speed (WS) has been proposed in this article to address this challenge. Initially, the wind turbine (WT) system was designed, and the IPMSG was proposed. A hysteresis controller (HC) and fuzzy logic controller (FLC) are the two controller types utilized in this model to control TR. This methodology used the EFLC to eliminate errors during the control. By using the proper membership function (MF) for boundary selection in the WDCSO algorithm, an enhancement was executed. Better performance in TR reduction was attained by the proposed model grounded in the analysis.

Nonlinear Force and Vibration Analysis of an Interior Permanent Magnet Synchronous Generator With Eccentricity Detection

In this article, an in-depth study on eccentricities and their resultant vibration characteristics of an interior permanent magnet synchronous generator (IPMSG) for portable power generation is proposed. Also, this article introduces the eccentricity detection through vibration tests, since the vibration patterns caused by eccentricities are unique. Three basic eccentricity cases are investigated, namely the static, dynamic, and elliptical. Air-gap radial flux density and radial force density profiles are theoretically analyzed through mathematical modeling. With the help of finite-element analysis, the unique force profiles are verified for IPMSG of different cases, and the tooth force chopping process is studied. With modal analysis and testing, the harmonic vibration responses are predicted. An IPMSG prototype is fabricated and an overall eccentricity evaluation is reported through vibration tests.

Multi-objective optimization design and Verification of Interior PMSG Based on Finite Element Analysis and Taguchi method

This paper proposes the optimal design process of an Interior permanent magnet synchronous generator (IPMSG) for wind power systems using the finite-element analysis (FEA). A multi-objective optimization design of PM generator based on Taguchi method is proposed. This paper takes the influence of the pole arc angle, magnet inset, magnet thickness, magnet width, stator tooth width and slot depth into consideration as a design parameters. The main characteristics of generator efficiency, torque ripple and output power are taken as optimization objectives. The orthogonal matrix is established according to the number of selected parameters and the level factor of each parameter and FEM is used to solve the experimental matrix. As a result, an improved generator was designed and selected, which had higher maximum output power and efficiency and lower torque ripple. Finally, a prototype IPMSG was manufactured based on analysis results and Taguchi method, and was tested. The experimental tests were conducted to verify the validity of the proposed design process and the effectiveness of the generator and as a result, perfectly cleared the optimization design.

Comparison of Flux-Switching and Interior Permanent Magnet Synchronous Generators for Direct-Driven Wind Applications Based on Nelder–Mead Optimal Designing

The permanent magnet flux-switching machine (PMFSM) is one of the most promising machines with magnets inserted into the stator. To determine in which applications the use of PMFSM is promising, it is essential to compare the PMFSM with machines of other types. This study provides a theoretical comparison of the PMFSM with a conventional interior permanent magnet synchronous machine (IPMSM) in the gearless generator of a low-power wind turbine (332 rpm, 51.4 Nm). To provide a fair comparison, both machines are optimized using the Nelder–Mead algorithm. The minimized optimization objectives are the required power of frequency converter, cost of active materials, torque ripple and losses of a generator averaged over the working profile of the wind turbine. In order to reduce the computational time, the substituting profile method is applied. Based on the results of the calculations, the advantages and disadvantages of the considered machines were revealed: the IPMSM has significantly lower losses and higher efficiency than the PMFSM, and the PMFSM requires much less rare-earth magnets and copper and is, therefore, cheaper in mass production.

Development of Wind IPMSG Based Bipolar DC Microgrids

This paper presents the development of a wind Interior Permanent-Magnet Synchronous Generator (IPMSG) based bipolar DC microgrids along with various switch-mode rectifiers. Firstly, the wind IPMSG is established and adequately controlled to possess satisfactory generating characteristics during different driven speeds and loads. Later, the boost switch-mode rectifier (SMR) based bipolar DC bus is established. Further, three-phase single-switch (3P1SW) boost SMR, three-phase two-switch (3P2SW) three-level boost SMR, and a three-phase three-switch (3P3SW) Vienna SMR are comparatively evaluated. Along with the proposed robust voltage and current controls, a well-regulated microgrid DC-bus voltage is established. Moreover, the voltage balancing control is proposed to minimize the imbalance in the bipolar DC-bus voltage. For the wind IPMSG having Vienna SMR, the commutation angle setting is adjusted to use the reluctance power component effectively.

A Wind Turbine Emulator Using Field-Oriented Induction Motor

This paper proposes a Wind Turbine Emulator (WTE) using an Indirect Field Oriented (IFO) Induction Motor (IM). The IM drive can be controlled as a conventional prime mover in speed mode, or a wind turbine in torque-speed mode via robust observed torque control. This paper presents key issues for establishing a high-performance IFO IM drive. Further, this study develops a wind turbine load Interior Permanent-Magnet Synchronous Generator (IPMSG) followed by a three-phase Vienna Switch-Mode Rectifier (SMR). It receives mechanical driven power from the WTE and establishes a 400V DC-link for the DC micro-grid. The good generating characteristics are achieved through proper controls of both the IPMSG and SMR. Various wind turbine torque-speed and power-speed characteristic curves under different wind speeds can be emulated by the developed WTE. The designed results are verified by simulations. The measured results indicate that the errors are within 1.5% and 1.0%, respectively, for the torque and the power compared to the designed ones. The maximum power point tracking (MPPT) function with good performance for the PMSG with Vienna SMR is achieved using the perturb and observation (P&O) approach. The dynamic and steady-state operating characteristics of the developed whole turbine emulator driven PMSG system are assessed experimentally.

Optimal design and verification of interior permanent magnet synchronous generator based on FEA and Taguchi method

Optimal design and verification of interior permanent magnet synchronous generator based on <scp>FEA</scp> and Taguchi method

Performance analysis of single phase interior permanent magnet synchronous generator

This work presents the performance analysis of a single phase interior permanent magnet synchronous generator. The stator magneto motive force (MMF) waveform of the single phase winding function was developed. The mathematical model in phase variables by which the performance of the generator can be investigated under various operating conditions was developed. Self-excitation of the generator was achieved through pre-excitation by the permanent magnet in the rotor, and then regulated by connecting 30μF capacitor across the terminals of the stator winding. The performances of the generator under constant speed, constant capacitor value and varying power factor loads was investigated. The voltage build-up characteristics and dynamic loss of load performance was studied. The magnitudes of the output power, real power, load voltage and load current increases with increase in load power factors while the phase voltage, phase current, capacitor current and the reactive power decreases with increase in power factor loads. The generator has shown to be capable of stand-alone power source. Simulations were carried out using the Simulink® toolkit in MATLAB® software. Keywords: Interior permanent magnet, phase variable model, single phase, load characteristic, dynamic loss of load

Efficiency improvement of IPMSG in the electric power generating system of a range‐extended electric vehicle

This study addresses an optimisation method for interior permanent magnet synchronous generators (IPMSGs) to improve the efficiency of the electric power generating system of a range-extended electric vehicle. The target operating point of the IPMSG is specified with an optimal operating line (OOL) of the newly developed two-cylinder engine. The performance and efficiency of the IPMSG throughout the OOL are numerically identified in association with finite element analysis (FEA). For optimal design, intelligent mesh adaptive direct search with clustering and elastic net, which has been validated as a global searching optimisation algorithm with fast convergence on electric machines, is applied for IPMSG to maximise efficiency based on FEA. Furthermore, the optimised prototype is experimentally validated via the resultant efficiency map built up by the static and dynamic dynamometer tests.

Analysis and Design of a Delta-Type Interior Permanent Magnet Synchronous Generator by Using an Analytic Method

The analytic analysis of delta-type interior permanent synchronous machines is difficult due to the absence of a useful analytic method, especially considering the high magnetic saturation effect of the machine. Hence, the nonlinear magnetic equivalent circuit (MEC) method, which considers the severe magnetic saturation of the iron core, is proposed in this paper. With the proposed nonlinear MEC method, the characteristics of the delta-type interior permanent magnet synchronous generator (IPMSG) are precisely calculated and the computational burden is remarkably reduced. The proposed MEC method is validated by comparing the calculated data with the experimental results.

Development of a Prime Mover Emulator Using a Permanent-Magnet Synchronous Motor Drive

This paper presents the development of a surface-mounted permanent-magnet synchronous motor (SPMSM) drive for constructing the prime mover emulators. It draws power from the mains via a single-phase boost type switch mode rectifier (SMR) with good line drawn power quality and well-regulated dc-link voltage. The SPMSM drive control scheme can be arranged to drive the tested generator in a conventional speed control mode or a specific wind turbine torque–speed control mode. For performing the prime mover loading test, an interior permanent-magnet synchronous generator (IPMSG) followed by a three-phase Vienna SMR is established. It receives the mechanical driven power from the prime mover and establishes a 400 V dc-link for a dc microgrid. Various wind turbine torque–speed characteristic curves under different wind speeds can be faithfully emulated by the developed prime mover. And the maximum power point tracking function for the IPMSG followed by Vienna SMR is achieved using the perturb and observation method. The established whole prime mover emulator driven IPMSG system is evaluated experimentally under autonomous and microgrid interconnected operation.

Model Predictive Direct Current Control of a Permanent Magnet Synchronous Generator Based on Flexible Lyapunov Function Considering Converter Dead Time

This paper proposes a dual-mode model predictive direct current control (MP-DCC) of a permanent magnet synchronous generator (PMSG). The proposed algorithm is capable of minimizing switching losses in a two-level synchronous generator side converter (SGSC). A new prediction model that takes the converter dead time into consideration when choosing the optimal switching state is introduced. The proposed prediction model provides a more accurate state prediction, ensuring that the states of the system stay inside the control invariant set in the steady state, even in the case of a significant converter dead time. To guarantee recursive feasibility and closed-loop stability, a flexible control Lyapunov function (CLF) is employed as an optimization problem constraint, which enables the minimization of switching losses both during transients and in the steady state. The influence of the converter dead time on the performance of the proposed algorithm is considered, and accordingly, a control invariant set is determined. Simulation results show that stator currents are kept within the control invariant set if dead time is taken into account in the prediction model. Furthermore, the proposed algorithm is implemented in a digital control system and experimentally verified on a 375 kW interior PMSG. Experimental results verify that the proposed control algorithm provides a successful flying start of the PMSG and show that the application of the flexible CLF results in a lower switching frequency, but also in higher current ripple. By adjusting the upper bound of the control invariant set, a desired tradeoff between the low stator current ripple and the minimization of switching losses can be achieved.

A Novel Sequential-Stage Optimization Strategy for an Interior Permanent Magnet Synchronous Generator Design

For an optimal design of an interior permanent magnet synchronous generator (IPMSG) for range the extended electric vehicle (REEV), many design variables and objective functions should be considered. Conventional optimization methods like the Taguchi method and multiobjective optimization algorithm have completeness or calculation time problems when solving the many design variables and objectives problems. To address these problems, a sequential-stage optimization strategy (SSOS) is proposed. In the first stage of the SSOS, the initial design result considering the various objective functions is derived by using the Taguchi method. In addition, the sensitive design variables are sorted through the calculation of synthetic signal to noise. In the second stage, the optimal solution for the sensitive design variables is derived using the surrogate assisted genetic algorithm (SAGA). The SAGA not only obtains an accurate and well-distributed Pareto front set but considerably reduces the number of function calls as well. In the last stage, the uncertainty consideration based on the worst-case scenario is applied to derive the robust optimal solution. By applying the proposed optimization strategy to the optimal design of IPMSG for REEV, an optimal solution is derived with fewer function calls, and the feasibility of the proposed optimization is verified by experimental results of manufactured generator.

An Enhanced Control Scheme for an IPM Synchronous Generator Based Wind Turbine With MTPA Trajectory and Maximum Power Extraction

This paper proposes an enhanced control scheme for a direct drive variable speed wind turbine with an interior permanent magnet (IPM) synchronous generator. The proposed control scheme incorporates maximum torque per ampere (MTPA) trajectory and maximum power extraction, which ensures the generation of required torque for maximum power extraction with minimum stator current. This in turn minimizes stator copper loss and excessive heat generated in the IPM synchronous generator. The performance of the proposed control scheme has been validated through rigours simulation and experimental studies under varying wind speed conditions. The simulation and experimental results demonstrate the efficacy of the proposed control method.

IPMSG을 이용한 풍력 발전 시스템의 최대 출력화 제어 특성

This paper proposes the variable wind generation system based on the direct torque control(DTC)for the interior permanent magnet synchronous generator. The proposed system can achieve the MPPT control without wind speed in addition to the speed and position sensorless control as well as the conventional current control method. The DTC has several advantages such as simply system configuration, ease of the flux weakening control and the sensorless control. The experimental results show the performance of the proposed wind generation system.

Open-Circuit Fault-Tolerant Control for Outer Switches of Three-Level Rectifiers in Wind Turbine Systems

A three-level converter is used as the power converters of wind turbine systems because of their advantages such as low-current total harmonic distortion, high efficiency, and low collector–emitter voltage. Interior permanent magnet synchronous generators (IPMSGs) have been chosen as the generator in wind turbine systems owing to their advantages of size and efficiency. In wind turbine systems consisting of the three-level converter and the IPMSG, fault-tolerant controls for an open-circuit fault of switches should be implemented to improve reliability. This paper focuses on the open-circuit fault of outer switches ( $S_{x1}$ and $S_{x4}$ ) in three-level rectifiers (both neutral-point clamped and T-type) that are connected to the IPMSG. In addition, the effects of $S_{x1}$ and $S_{x4}$ open-circuit faults are analyzed, and based on this analysis, a tolerant control is proposed. The proposed tolerant control maintains normal operation with sinusoidal currents under the open-circuit fault of outer switches by adding a compensation value to the reference voltages. The effectiveness and performance of the proposed tolerant control are verified by simulation and experiment.

소수력 발전용 고효율 100kW 발전기의 설계해석 및 경제성 분석

This paper shows the design of the 100 kW IPMSG for small hydraulic power generator. The high-efficient generator, method of the dual layer interior permanent magnet was studied to improve the method of the single layer interior permanent magnet, which is mostly used. Analysis of magnet arrangement and cogging torque was done by FEM. According to structure analysis of dual layer interior permanent magnet, the amount of usage of the permanent magnet was reduced and cogging torque was decreased as well. With these successful results, the high-efficient generator design was accomplished. Based on the results of the structure analysis, the test product was designed and manufactured. And the design values and performance outputs were compared and verified with success. Also, the economic feasibility was conducted based on the electric power generated from the test product installed at the site. By the B/C analysis, in case that only SMP was analyzed, B/C ratio was 1.24 at the discount ratio of 5.5%, which considered to be economically feasible. The study is expected to be used for the application of developing large scale high-efficient interior permanent magnet synchronous generator.

Development of a Wind Interior Permanent-Magnet Synchronous Generator-Based Microgrid and Its Operation Control

This paper presents the development of a wind interior permanent-magnet synchronous generator (IPMSG)-based dc microgrid and its operation control. First, the derated characteristics of PMSG systems with various ac/dc converters and operation controls are comparatively analyzed. Then, the IPMSG followed by a three-phase Vienna switch-mode rectifier is developed to establish the common dc bus of dc microgrid. Good developed power and voltage regulation characteristics are achieved via the proposed commutation tuning, robust current, and voltage controls. Second, a single-phase three-wire inverter is constructed to serve as the test load. Good ac 220 V/110 V output voltage waveforms under unknown and nonlinear loads are preserved by the developed robust waveform tracking control scheme. Third, a battery energy storage system is established, and the fast energy storage support response is obtained via the proposed droop control approach with adaptive predictive current control method. In addition, a chopped dump load is equipped to enhance the energy balance control flexibility.

특수차량용 엔진 직결형 IPMSG의 넓은 속도운전 범위를 위한 부스트/약자속 제어기에 관한 연구

This paper proposes a boost/flux-weakening controller (BFWC) for wide speed operation range having engine and interior permanent magnet synchronous generator (IPMSG) for special equipment vehicle. The proposed BFWC exploits direct torque/flux control (DTFC) scheme based on space vector modulation method to control the constant DC voltage output within the entire speed operation range of engine. And, to improve the response characteristics of maximum torque per ampere (MTPA) operation and flux-weakening operation, the MTPA and flux-weakening feed-forward controllers are applied. To estimate feasibility and usefulness of the proposed controller, the simulation and experimental results are compared.