Low-speed Permanent Magnet Research Articles

Comprehensive Comparison of Different Rotor Structures of Low-Speed Permanent Magnet Motor

Comprehensive Comparison of Different Rotor Structures of Low-Speed Permanent Magnet Motor

Low-speed permanent magnet generator for use in a compact wind turbine

PurposeThis paper aims to present the project of a permanent magnet synchronous machine which can be used as generator in the vertical axis wind turbine.Design/methodology/approachIn the study, finite element analysis was used to perform simulation research of electrical machines. Based on the simulation studies, an experimental model was built. The paper presents also selected experimental results.FindingsDuring the research, it was found that the radial arrangement of the permanent magnets is more favorable than the tangential one for the selected structure of the generator with permanent magnets.Research limitations/implicationsDuring the experimental research, a problem was encountered involving the correct control of the constructed generator at low rotational speeds.Practical implicationsThe proposed solution can be used in low-speed vertical axis wind turbines.Social implicationsThe presented research fits the global trend toward the use of alternative and renewable energy sources.Originality/valueThe paper presents new simulation studies of two low-speed generator topologies. The results for the radial and tangential arrangement of the permanent magnets in the rotor were verified. Based on this research, an experimental prototype of a generator for a slow-speed vertical axis wind turbine was built.

Friction Loss Calculation and Thermal Analysis of Submerged Low Temperature High Speed Permanent Magnet Motor

Friction Loss Calculation and Thermal Analysis of Submerged Low Temperature High Speed Permanent Magnet Motor

Design and Performance Analysis of a Staggered Vernier Generator for Wave Power Generation

In this paper, a staggered vernier generator suitable for a counter-rotating self-adaptable WEC is proposed to meet the energy demand of the small-scale engineering equipment in the deep sea. According to the vernier effect of the magnetic gear, the generator modulates the low-order rotating magnetic field generated by the rotation of the low-speed permanent magnet rotor into a high-order magnetic field rotating at a high speed, thereby realizing the acceleration of the generator magnetic field. A staggered structure permanent magnet vernier generator with 18 teeth/28 poles is designed. The main magnetic flux path on the staggered structure in the staggered vernier generator is analyzed, and the air-gap magnetic field distribution of the generator is analyzed with the help of numerical simulation software. The influence of different design parameters on the vernier generator is discussed. The staggered vernier structure can improve the main magnetic flux of the generator, reduce the magnetic flux leakage, and improve the performance of the generator without adding additional structures and materials.

Comparison of Temperature Characteristics of Outer Rotor Low-Speed PM Motors Considering Magnetic Load and Current Density

In the electromagnetic design process of the outer rotor of a low-speed permanent magnet motor (LSPMM), due to the different heat dissipation conditions of the stator core and the stator winding, the selection of different magnetic loads and stator current densities will produce different temperature distributions even under the same efficiency. In the existing literature, the effects of magnetic load and current density on temperature distribution are rarely studied, which makes it difficult for designers to select optimal electromagnetic parameters to achieve better temperature performance. Therefore, in this paper, the comparison of temperature characteristics considering magnetic load and current density is conducted based on an outer rotor LSPMM. Firstly, the structure and parameters of an initial scheme of a 200 kW 56 rpm motor is determined, and the electromagnetic and temperature characteristics of the initial scheme are obtained through two-dimensional finite element analysis (2D-FEA) using Ansys Maxwell and Motor-CAD software. Secondly, by comparing the temperature and loss characteristics under different magnetic loads and different current densities, the effect of magnetic load on temperature and the effect of current density on temperature are obtained. Furthermore, four different schemes are proposed, and the loss and temperature characteristics of the four schemes under rated load are also compared to obtain the comprehensive effects of magnetic load and current density on temperature. Next, a final scheme is determined based on the above analysis, and the temperature characteristics of the final scheme and the initial scheme are compared to verify the validity of the conclusions. Finally, a prototype is built and tested to verify the feasibility of the conclusions. For LSPMM design, the results and several measurements provided in this paper can help researchers to choose a better optimization scheme to achieve good temperature performance.

Multi-Objective Optimization for Outer Rotor Low-Speed Permanent Magnet Motor

For outer rotor low-speed permanent magnet motors (LSPMMs), in the optimization design process, not only is the electromagnetic performance optimized, but the influence of the thermal load and copper loss on the temperature in the electromagnetic parameters should also be considered. However, these optimized designs that comprehensively consider electromagnetic performance and temperature characteristics are rare in the existing literature. Therefore, this paper focuses on a multi-objective optimization process considering efficiency, thermal load and copper loss. Firstly, according to the initial design, the influence of the design parameters on the efficiency and thermal load is analyzed, and the range of optimization parameters is determined. Next, the response surface is built, the response-surface analysis of electromagnetic performance is performed, and the parameter sensitivity is calculated. Then, the multi-objective optimization design is carried out by comprehensively considering the electromagnetic performance and temperature. Finally, compared with the initial scheme, the optimized scheme improves the efficiency and reduces the temperature, and the optimized scheme is verified by experimentation on a 22 kW, 56 rpm LSPMM prototype, which can provide a reference for the multi-objective optimization of LSPMMs by comprehensively considering the electromagnetic performance and temperature.

Research on a Limit Analytical Method for a Low-Speed Micro Permanent Magnet Torque Motor with Back Winding

The conventional permanent magnet torque motor (PMTM) is slotted on the inner surface of the stator core. When the size of the stator core is small, the winding coils are difficult to embed into the slots. To solve the problem, a novel PMTM is presented, which is slotted on the outer surface of the stator core. As a result, the winding coils can be conveniently embedded into the slots from the outer surface of the stator core. The novel structure of the PMTM with back winding (BWPMTM) is introduced, and the advantage of the novel structure is analyzed. Furthermore, this paper proposes a limit analytical method to solve the optimal parameters of the motor which comprehensively considers four constraints: no-load back electromotive force (EMF), torque, temperature and slot space factor. The optimal parameters of the motor are directly solved to maximize torque density within the constrained range. This method avoids repeated iterative processes and greatly reduces the amount of calculation for PMTM design. Electromagnetic performance and thermal performance are analyzed based on the finite element model (FEM). Finally, the building of a prototype and the experimental results obtained with it are discussed. The rationality of the novel structure and the limit analytical method are verified.

Modelling and Analysis of Wind Turbine using Permanent Magnet synchronous generator for Maximum Power Tracking Control

This research uses Matlab/Simulink simulation tools to analyse and simulate the performance of a wind power system powered by a low-speed Permanent Magnet Synchronous Generator (PMSG). A wind turbine (WT), PMSG, maximum power point tracking (MPPT), a three-phase diode bridge rectifier, a dc bus connected to a capacitor, and a PWM voltage source inverter regulated by a current source are all part of the system. With an MPPT control, the optimum coefficient of performance parameter was attained in the WT model as a function of wind velocity. The use of low-speed PMSG, which results in improved efficiency, eliminates the need for a gearbox. The ac output power obtained from PMSG is supplied to a three-phase rectifier bridge, which allows for maximum power extraction by using the boost converter's optimal voltage and current settings. The total system is connected to the electrical utility using a current source PWM inverter for dc/ac conversion.

An efficient multidisciplinary design research for the integrated low speed permanent magnet motor system based on analytical and numerical hybrid analysis

This paper proposed an efficient high-accuracy multidisciplinary design process for the integrated system of low speed permanent magnet synchronous motor (PMSM). The method combined the analytical models and numerical models together to get an efficient way to design the integrated motor. In the proposed method, a magnetic equivalent circuit (MEC) model of the motor is established first based on one modular structure of the motor, and the finite element analysis (FEA) numerical model is used to correct the results of the analytical model next. Then the iron loss, copper loss, and switching loss from the results of the electromagnetic model are loaded to a proposed simplified lumped parameter fluid-thermal model. This fluid-thermal coupled analytical model cuts the fluid flow into several parts depends on the parameters of the cooling path, each parts act as a current controlled voltage source coupled with these parameters. And because this coupled model has controlled sources, the conventional node voltage method is not suitable anymore, so a more universal list parameter calculation method is proposed for this coupled model. Finally, the computational fluid dynamics (CFD) model is used to correct the results of the analytical model as well. The aim of the above analytical models is to quickly get the suitable multidisciplinary pre-design or design trends, and this pre-work or trends will reduce the design process time of the high-accuracy numerical models.

NIPPF versus ANIPPF controller outcomes on semi-direct drive cutting transmission system in a shearer

Nonlinear integral positive position feedback (NIPPF) and adaptive nonlinear integral positive position feedback (ANIPPF) controllers are used in a shearer's semi-direct drive cutting transmission system, which is powered by a low speed and high torque permanent magnet synchronous motor (PMSM). The transmission system's torsional vibration characteristics were investigated with internal parameter and external cutting load excitation changes caused by harmonic force. In the case of primary and 1:1 internal resonance, an analytic solution is obtained by employing the averaging technique to solve the nonlinear differential equations and modeling the system with NIPPF and ANIPPF controllers. The Poincare portraits were created to imagine how the PMSM would behave around their fixed points. A good match is found when the approximate solutions are compared to the numerical simulations via the Runge–Kutta method fourth-order (RK4). The linearized stability strategy is used to ensure stability near fixed points in the autonomous system. Before and after control, the steady-state amplitude and stability of nonlinear systems were investigated and analyzed. Optimal system operation conditions and frequency response curves (FRCs) were examined at various controller and system parameter values. Numerous system characteristics were found to have an effect after being combined with NIPPF and ANIPPF. The numerical and analytical solutions at time-history and FRCs were compared using the MATLAB program to confirm their comparability. This study's findings were compared to those found in the literature. We conclude from this analysis that the ANIPPF controller provides the best system control. The calculations also revealed that ANIPPF is the most effective controller. Finally, the controls suppress the system's vibration amplitude and chaos motion. The outcomes of this study were used to develop a theoretical foundation for the shearer semi-direct drive cutting transmission system's design and construction.

Design and characteristic analysis of dual-excitation and dual-modulation axial permanent magnetic gear

In order to solve the problems of serious axial and tangential leakage and low torque density in the magnetic circuit axial permanent magnet gear (APMG), an external regulating ring is introduced on the basis of APMG to form a dual-excitation and modulation APMG structure, namely DEM-APMG. The low speed rotor of DEM-APMG is clamped between the inner and outer magnetizing rings to generate dual-excitation field (i.e. dual excitation). At the same time, the inner and outer magnetizing rings modulate the low speed rotor dual-directionally modulation (i.e. dual modulation). The axial and tangential leakage flux of APMG can be converted into useful harmonics to increase the output torque and torque density on the basis of APMG. In this study, mathematical analysis is used to describe the air gap magnetic density and electromagnetic torque model of a DEM-APMG, which essentially describes the root cause of the increase in torque density. Using 3D finite element static and dynamic simulations, the transmission characteristics of the APMG and DEM-APMG are compared and analyzed. Results show that the maximum static torque of the DEM-APMG high-speed and low-speed rotors with the same outer diameter increase by 22.7% and 23.8%, respectively, compared with APMG, 26% and 29%, respectively, in steady-state operation, and the torque density increases by 24%. The influence of the primary structural parameters on the transmission characteristics is also investigated using the control variable method. Results show that the duty cycle of the magnet adjusting block, the axial length of the high-speed permanent magnet and the low-speed permanent magnet have the strongest effect on the torque density of the DEM-APMG. When the axial length of the high-speed permanent magnet and low-speed permanent magnet is 8mm, and the duty cycle is 0.4, the torque density can reach the optimal value of 156kNm/m3.

Short-Circuit Characteristics of Superconducting Permanent Magnet Generators for 10 MW Wind Turbines

Superconducting permanent magnet generators (SCPMGs) are a potential candidate for 10 MW direct-drive wind turbine applications. This paper presents two 10 MW SCPMG designs using MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> cables for the armature winding and investigates the short-circuit characteristics of the designed SCPMGs. The first part of the results shows that the SCPMGs can double the shear stress of a conventional low-speed permanent magnet (PM) generator (from 65 kPa to 130 kPa) whilst avoiding demagnetization of the PMs in rated-load operation. However, the power factor has to drop to a range of 0.7-0.8. The second part of the results shows that during a sudden three-phase short circuit, the superconducting armature winding is prone to quench and the PMs are likely to be demagnetized in both proposed designs.

Online Diagnosis of Slight Interturn Short-Circuit Fault for a Low-Speed Permanent Magnet Synchronous Motor

Online diagnosis of slight interturn short-circuit fault (ISCF) has always been difficult in low-speed permanent magnet synchronous motors (PMSMs). It is found that the residual zero-sequence voltage exists in healthy PMSMs due to the inherent unbalance of a low-speed motor. This article proposes a new ISCF diagnosis method based on zero-sequence voltage vector decomposition to solve this problem. The voltage vector whose phase angle is closest to the ISCF phase angle is extracted from the zero-sequence voltage vector, which improves the sensitivity of fault phase identification. Furthermore, the method of extracting phase voltage from PWM duty-cycle control voltage is proposed, which can reduce the error caused by measuring zero-sequence voltage with three-phase balanced resistance. Experiments demonstrate that the online detection limit of ISCF is reduced from 5% to 1% (short-circuit ratio) for a low-speed PMSM.

Analysis of torsional vibration characteristics and time delay feedback control of semi-direct drive cutting transmission system in shearer

Abstract The semi-direct drive cutting transmission system driven by low speed and high torque permanent magnet synchronous motor (PMSM) in shearer is a typical electromechanical coupling system. In this paper, the torsional vibration characteristics of the transmission system with internal parameter and external cutting load excitation changes are studied. Considering the torsional vibration angle and the air gap magnetic field energy of the PMSM, the torsional vibration model of the electromechanical coupling transmission system is derived by the Lagrange-Maxwell equation. Then, in the case of 1:1 internal resonance and external resonance, the first-order approximate solution is obtained by multiple scale method, and the influence of cutting load excitation and current on the torsional vibration characteristics of the rotor system is analyzed. In addition, the numerical simulation is used to study the vibration jump phenomenon of the nonlinear electromechanical coupling system. The influence of the cutting load excitation on the chaos motion is obtained by the bifurcation diagram and maximum Lyapunov index map. Finally, the vibration amplitude and chaos motion of the rotor system are suppressed by the time delay feedback controller. The research results can provide a theoretical basis for the design and manufacture of the shearer semi-direct drive cutting transmission system.

3D-printed materials based low-speed permanent magnet generator for energy harvesting applications

Abstract This work presents the study about the practicability of building a low-speed permanent magnet generator suitable for energy harvesting applications using 3D-printed structures. 3D-printer is used to prepare phototype of proposed generator. The major parts of the proposed device are fabricated through Polylactic Acid and permanent magnet materials. The prototype permanent magnet generator is tested with rotational speed under low speed condition. The experimental results have been shown that the construction generator can generate the electrical energy to charges the battery with maximum voltage at battery terminal of 1,136 mV

VERTICAL AXIS WIND TURBINE DESIGN FOR MOVEMENT PERMANENT MAGNETIC GENERATORS OF AXIAL TYPE

One of the alternative energy source that can be developed is the Wind Power Plant. The need for electrical energy that continues to increase, it takes not a little time to build a power plant. System planners must also be able to see the possibilities of the development of the power system in the years to come. Indonesia is a country that has abundant energy resources, one of which is a source of wind energy. Indonesia which is an archipelagic country and one of the countries located on the equator is a factor, that Indonesia has abundant wind energy potential. In this study the output that produced is a renewable energy product, which is a power plant product in the coastal area. In the previous study a low-speed permanent magnet generator has been produced which can be driven by wind turbines which will be continued through the design of vertical type wind turbines. The results of this study can then be developed, especially for electricity generation products in the coastal region. In the process of planning and manufacturing vertical type wind turbines, to produce enough power to meet household electricity needs should be based on several factors that support the effectiveness of the power produced by the turbine, namely: Turbine Dimensions (Length and Blade Width), Material Strength , Shaft, Bearing and Generator Shaft

Submersible direct-drive progressing cavity pump rodless lifting technology

Abstract Submersible electrical motor direct-drive progressing cavity pump (PCP) rodless lifting was studied to solve the traditional rod-drive pump problems, such as rod-tubing wearing, low efficiency and short running time. The theoretical researches and laboratory experiments of key tools such as submersible motor and the construction technology of lifting system were introduced. The field application and economic benefit were analyzed and compared with the traditional rod pumping unit. A new low speed and large torque permanent magnet synchronous motor was developed. This motor was used to drive PCP without gear reducer, which improved the reliability and feasibility. It can run at the speed from 50 to 500 r/min with stepless speed regulation, and it can perform high efficiency and large torque. Besides, other key supporting tools, such as motor protector and flex shaft, were developed. The submersible electrical motor direct-drive PCP technology can be used in a 139.7 mm (5.5 in) casing well, with daily output ranging from 5 to 50 m3. Until now, the technology has been deployed more than 100 wells. The field application results show that it eliminates the rod-tubing wearing and saves electric energy by more than 30% compared with the traditional rod pumping unit. And it also makes the oil produced in a safe and environmental friendly way.

Design And Implementation Of Ls-Pmsg For Small Scale Hydro Power Plant

- In conventional power system, synchronous generator which characterized by high-speed operating condition has been widely implemented. However, those high-speed synchronous machines are not suitable for a power plant powered by renewable energy (RE) due to uncertain feature of renewable resources. To overcome this problem, an electrical machine with low-speed characteristic is required for ensuring stable operation and maintaining output power of the RE based distribution generation (DG) unit. In this paper, a low-speed permanent magnet synchronous generator (LS-PMSG) is designed and implemented. To realize low-speed operation capability, the multi-stages permanent magnet synhcronous machine is proposed. The multi-stages machine equipped with two stators and three rotors construction. From the experimental results, it was monitored that output voltage of single rotor of the designed machine was 35 V. Moreover, to increase the output voltage to 50 V, those three rotors can be connected in series.

Influence of Permanent Magnet Characteristic Variability on the Wind Generator Operation

Abstract The paper discusses problems concerning the influence of permanent magnet material characteristics on the low-speed permanent magnet generator losses and output characteristics. The variability of the magnet material and its effect on the output parameters of the machine has been quantified. The characteristics of six different grades of neodymium permanent magnets have been measured and compared to the supplier specification data. The simulations of the generator have been carried out using transient finite element analysis. The results show that magnet materials from different suppliers have different characteristics, which have a significant influence on the generator output parameters, such as efficiency and power factor.

Development and Field Trials of Ultra Low Wind Speed Vertical Axis Wind Turbine (VWAT) for Home Application

Objectives: The turbine is of 1.5 m diameter and two bays of 0.5 m length blades NACA 0015 airfoil profile is used for the fabrication of hydrofoil blades. Glass fibre reinforced poly pipeline is used for the fabrication of the blades. The blades are assembled to a 50mm KTEC pipe to form a 1.5 m diameter ring. 200 watts ultra low speed Permanent Magnet Alternator (PMA) was used with suitable electronic circuit and battery backup. Methods/Statistical Analysis: Filed trials were conducted in the salt extraction filed of Chemfab Industries at Marakkanam. Since the initial results are encouraging and proves the technology of the concept, it is proposed to develop more turbines. Findings: In this paper development and results of the field trials of an ultra low wind speed vertical axis wind turbine are presented. Application/Improvements: This type for use in the coastal areas with larger dimensions to harvest higher green energy.