Permanent magnet rotor e1655961736623.jpeg - @article{osti_1349258, title = {Brushless and Permanent Magnet Free Wound Field Synchronous Motors for EV Traction}, author = {Ludois, Daniel C. and Brown, Ian}, abstractNote = {This final report presents an advanced electric motor design for vehicles. The motor is a wound rotor synchronous machine whose rotor coils are …

 
A double-sided permanent magnet rotor with a single stator [2, 3] can offset the axial attraction and increase the output power at the cost of an increased weight. The double-sided permanent magnet rotor design can also reduce bearing wear and noise problem compared with a single-sided structure, which thus increases the generator …. Searchterm

In the same way in , through FEM simulations and experimental results, a simple dynamic abc model for brushless permanent magnet motors, under demagnetisation faults, is presented and validated. The strategies based on the analysis of the harmonics produced by rotor demagnetisation in the phase currents or the EMF are …The prototype machine is an axial-flux permanent-magnet machine with a two-rotor–one-stator configuration. The nominal power of the machine is 300 W and the nominal rotational speed is 500 rpm. The magnets are neodymium iron boron magnets. Twelve magnets are mounted on the rotor surface and 12 magnets buried on the rotor (Fig. 12a).Apr 1, 2023 · The rotor spinning at high speed generates a large tensile stress. Once the yield strength of the permanent magnet (PM) is exceeded, the permanent magnet will be broken. Therefore, a high-strength sleeve must be installed outside the permanent magnet [3, 4]. Many researchers have conducted extensive study on rotor strength analysis of HSPMSM ... In order to improve the performance of synchronous motors, especially in dynamic-transient conditions, induction damper cages are usually used in the rotor structure. In this paper, a new hybrid structure of an axial-flux motor is proposed, which uses a permanent magnet (PM) rotor and an unpaired induction damper cage with …1 Introduction. Over the past decades, the development of the power train with simple structure and high reliability has always been a hot topic in academic research [].Traditional power train with DC motor with double rotor has the shortcomings of poor efficiency and excessive noise [2, 3].Compared with DC motor, permanent magnet …Summary. PM (Permanent Magnet) Type: uses permanent magnets, moderate torque, low to mid-speed. VR (Variable Reluctance) Type: toothed rotor/stator, low torque, mid to high speed. Hybrid Type: combines permanent magnets and teeth, good combination of torque and speed.Non−Magnetic Rotor Core Rotor Magnets Rotor Pole Pieces Figure 2: Axial View of a Flux Concentrating Motor The geometry of one type of internal magnet motor is shown …The demagnetization of rotor permanent magnet is described in terms of rotor offset caused by demagnetization, demagnetization angle, decrease of air-gap MMF at the demagnetization …A computationally efficient design of interior permanent magnet (IPM) motor rotor features is investigated utilizing analytical methods. Over the broad operating range of IPM machines, interactions of MMF sources, permeances, and currents result in torque harmonics. The placement of traditional rotor features along with sculpt features are …To replace permanent magnets on an electric bike rotor, you’ll need a few essential tools: a screwdriver, pliers, and possibly a heat gun. Additionally, gather the …Jun 9, 2022 · To solve the problem of tension stress caused by centrifugal force and caused by high-speed operation of permanent magnet (PM) rotor, a FeCo-based PM rotor structure model is proposed. Based on the thick-walled cylinder theory, the uniform analytical calculation formulas of strain field, displacement field, and stress field of high-speed permanent magnet rotor are derived, and the stresses of ... To replace permanent magnets on an electric bike rotor, you’ll need a few essential tools: a screwdriver, pliers, and possibly a heat gun. Additionally, gather the …The traditional bearingless synchronous reluctance motor (BSynRM) with salient pole rotor has some drawbacks such as high suspension force ripple, low torque density and low power factor. To overcome the above shortcomings, the permanent-magnet-assisted bearingless synchronous reluctance motor (PMa-BSynRM) is …A commercial traction motor (Prius 2010), designed with Nd-Fe-B magnets for maximum power 60 kW and maximum speed 13,500 rpm, is used as the baseline for comparing the HRMM design. The HRMM design shows comparable performance with the commercial design for the given speed range with ~ 50% reduction in critical rare earth …Abstract--Multi-phase permanent magnet assisted synchronous reluctance motor (PMa-SynRM) is proposed as one of the optimal machine designs for vehicular applications such as electric vehicles (EVs) due to their fault tolerant operation capability. However, optimization of the multi-phase PMa-SynRMs for in-wheel applications in EVs and aircrafts ... Magnet Rotors. Magnetic rotor, or permanent magnet rotor is the non stationary part of a motor. The rotor is the moving part in an electric motor, generator and more. Magnetic rotors are designed with multiple poles. …An internal permanent magnet synchronous machine (IPMSM) was designed for heavy-load traction vehicles applied in port transportation. Based on finite element analysis (FEA), the rotor iron core topology was optimized with the most attention paid to cogging torque and torque ripple. The influences of the iron core on the air-gap …Nov 27, 2021 · In this study, an analytical model is established to efficiently compute the magnetic field and unbalanced magnetic pull (UMP) in axial-flux permanent-magnet motors (AFPMMs). The effects of stator slotting, end effect, and rotor eccentricity on the magnetic field and forces were investigated. Static and dynamic eccentricities are analyzed and considered in the model. An effective function of ... Axial-flux permanent-magnet (AFPM) motors are a kind of important motor with compact structure, high power density and high torque density. In this review, the progress of AFPM motors and their key technologies are analyzed and described, with emphasis on the topological structures, design and optimization methods and control …an interior permanent magnet (PM) synchronous motor into a hybrid motor. This hybrid technology uses a conventional induction rotor cage to bring the motor up to its slip speed just like any traditional induction motor. Once at slip speed, the powerful interior magnets pull the rotor into true synchronous speed with the rotating magnetic field.Feb 9, 2018 · Electric machines with permanent magnet rotors are becoming increasingly popular due to the high power density that they offer relative to other configurations. Where the speed of rotation is high, the magnets are typically mounted on the surface of the rotor and retained by an outer sleeve. In the literature, a variety of analytical models have been proposed to aid the mechanical design ... 2.2 External rotor permanent magnet motor rotor air gap magnetic field When the motor is running at no load, the air gap magnetic field is provided by the permanent magnet alone. The generated magnetic field rotates together with the rotor and the rotational speed is synchronous speed.In this study, an analytical model is established to efficiently compute the magnetic field and unbalanced magnetic pull (UMP) in axial-flux permanent-magnet motors (AFPMMs). The effects of stator …In a permanent-magnet machine, where the magnets reside on the rotor, there is no secondary winding. However, the permanent magnet can be modeled with a fictitious secondary winding excitation [1,2] and therefore the stator leakage inductance can be defined. Care must be taken that permanent magnets do not get demagnetized due to excessive ... The prototype machine is an axial-flux permanent-magnet machine with a two-rotor–one-stator configuration. The nominal power of the machine is 300 W and the nominal rotational speed is 500 rpm. The magnets are neodymium iron boron magnets. Twelve magnets are mounted on the rotor surface and 12 magnets buried on the rotor (Fig. 12a).Nov 11, 2021 · According to the location of permanent magnet on the rotor, the permanent magnet synchronous motor rotor mainly has two different structures: surface-mounted and buried. Due to the strength limitation of silicon steel sheets, the application of buried rotor in the high-speed field is relatively smaller than surface-mounted rotor. High Performance Magnets and Precision Assemblies. Arnold’s high-performance permanent magnets have a wide variety of applications, from electric motors on ships, aircraft, and motorsport cars to pump couplings, batteries, solar panels and NMR Equipment. Our diverse markets allow us to keep our technologies on the leading edge of innovation. Eddy current losses in magnets are a major consideration in the rotor design of permanent magnet synchronous motors (PMSMs). Stator design choices and the use of modern inverters with high switching frequency introduce harmonics that can contribute to significant losses in the magnets, causing the rotor to heat up. In typical …Apr 1, 2023 · The rotor spinning at high speed generates a large tensile stress. Once the yield strength of the permanent magnet (PM) is exceeded, the permanent magnet will be broken. Therefore, a high-strength sleeve must be installed outside the permanent magnet [3, 4]. Many researchers have conducted extensive study on rotor strength analysis of HSPMSM ... This paper presents a design method of the basic model of high-speed surface-mounted permanent magnet synchronous motor (SPMSM) comprehensively considering the mechanical and electromagnetic properties based on the subdomain method. In the rotor design stage, the mechanical stresses of the permanent magnet …where Φ is the magnet flux crossing the air gap, R is the total reluctance through the flux paths and θ is the rotor angle. It is clear that if the reluctance R does not vary as the rotor rotates, then the cogging torque T cog is zero. From this point of view, the cogging torque can be improved by changing the V-shape rotor structure variables …Rotor The rotor is made of permanent magnet and can vary from two to eight pole pairs with alternate North (N) and South (S) poles. Based on the required magnetic field density in the rotor, the proper magnetic material is chosen to make the rotor. Ferrite magnets are traditionally used to make permanent magnets. As the technology advances, rare Purpose This paper comprehensively analyses the radial electromagnetic (EM) force by unit area and vibration characteristics in a permanent magnet synchronous motor (PMSM). This provides the possibility to verify the action law, causes, and influencing factors of vibration deformation and provides new ideas for vibration management. …A permanent magnet synchronous generator is a generator where the excitation field is provided by a permanent magnet instead of a coil. The term synchronous refers here to the fact that the rotor and magnetic field rotate with the same speed, because the magnetic field is generated through a shaft mounted permanent magnet mechanism and current is induced into the stationary armature. Traditional diesel generators on a merchant ship, composed of a wound rotor synchronous generator and a four-stroke diesel engine, supply electrical power for various loads. Recently, shaft generators for merchant ships have been increasingly replacing diesel generators to reduce CO2 emissions through fuel efficiency improvement. In particular, …A double-sided permanent magnet rotor with a single stator [2, 3] can offset the axial attraction and increase the output power at the cost of an increased weight. The double-sided permanent magnet rotor design can also reduce bearing wear and noise problem compared with a single-sided structure, which thus increases the generator …Summary. PM (Permanent Magnet) Type: uses permanent magnets, moderate torque, low to mid-speed. VR (Variable Reluctance) Type: toothed rotor/stator, low torque, mid to high speed. Hybrid Type: combines permanent magnets and teeth, good combination of torque and speed.The equivalent magnetic circuit (EMC) is employed both to design the mechanical parameters of the rotor while considering nonlinear magnetic saturation effect and to analyze the magnetic characteristics of the air-gap of the motor. This paper considers the design and performance evaluation of interior permanent magnet …Mar 29, 2018 · For the high-frequency permanent magnet electrical machine, a reasonable mechanical aspect design is crucial to meet its stability and reliability. This study focuses on the accurate modelling and analysis of the natural frequencies and modes of the rotor assembly for a designed and manufactured 100 kW 32,000 r/min motor. Several new topologies without permanent magnets in the rotor have been published recently [3]. These topologies feature either a low mechanical complexity [4], a wide air gap to rotor radius ratio [5], further called gap factor G, or a good torque per stator permanent magnet mass ratio [6]. In theory, reluctance rotors have advantages for very ...Magnet Rotors. Magnetic rotor, or permanent magnet rotor is the non stationary part of a motor. The rotor is the moving part in an electric motor, generator and more. Magnetic rotors are designed with multiple poles. …The development of high-speed (operating at a rotation speed above 10,000 rpm) synchronous electric machines with permanent magnets is currently a relevant design direction [1,2,3,4,5].The structure of the rotor of synchronous machines with permanent magnets is a system of permanent magnets kept from their radial movement with the …A high-speed (HS) permanent magnet (PM) synchronous motor (HSPMSM) with a carbon fiber-reinforced plastic (CFRP) protective sleeve in the surface-mounted rotor was explored in this study.To enable a successful transition, the availability of resources must be ensured. In particular, rare earth materials used in permanent magnets of permanent magnet synchronous machines (PMSM) are already considered as a critical resource. Therefore, high performance magnets of existing PMSM rotors must be recovered and …For the high-frequency permanent magnet electrical machine, a reasonable mechanical aspect design is crucial to meet its stability and reliability. This study focuses on the accurate modelling and analysis of the natural frequencies and modes of the rotor assembly for a designed and manufactured 100 kW 32,000 r/min motor.The prototype machine is an axial-flux permanent-magnet machine with a two-rotor–one-stator configuration. The nominal power of the machine is 300 W and the nominal rotational speed is 500 rpm. The magnets are neodymium iron boron magnets. Twelve magnets are mounted on the rotor surface and 12 magnets buried on the rotor (Fig. 12a).The advantages of choosing Sintex® magnetic rotors are as follows: Patented solutions. Complete solutions. 100% sealed enclosure – can run as wet runner. Corrosion-resistant materials. High efficiency / low energy loss. Maintenance-free. Long service life. …2.2 External rotor permanent magnet motor rotor air gap magnetic field When the motor is running at no load, the air gap magnetic field is provided by the permanent magnet alone. The generated magnetic field rotates together with the rotor and the rotational speed is synchronous speed.Axial flux permanent magnet (AFPM) machines are good candidates for electric vehicle applications due to their high torque density, improved efficiency, and better flux distribution; thus, they are often used. A dual-rotor single-stator AFPM machine with four differently shaped permanent magnet (PM) rotors is investigated. The main aim of …Nov 15, 2016 · Any device that turns electricity into motion, meaning electrical energy into mechanical energy, is called an electric motor. Due to the continuous need for increased power density and high efficiency levels, PM motors (permanent magnet) are now common among today’s motor market. The first electric motors used bar magnets, and were more or ... This study performs a dynamic modeling and analysis of the axial uniform demagnetization rotor of a motor to investigate the demagnetization peculiar for permanent magnet synchronous motor (PMSM). First, the air-gap change in the motor is analyzed by constructing a dual coordinate system of stator and rotor, and the unbalanced magnetic …In this work we proposed to study the use of permanent magnet synchronous motors (PMSM) for railway traction in the high-speed trains (HST) of Renfe Operadora (the Spanish national railway operator). Currently, induction motors (IM) are used in AVE classes 102–112 trains, so, the IM used as a traction motor in these trains has …Dual Rotor Axial Flux Generator (DRAFG) is a permanent magnet axial flux generator commonly used for low speed power generation using wind power. This generator can generate useful amount of ...Aug 25, 2020 · Permanent Magnet AC Motors. Like an induction motor, a permanent magnet motor has a Stator configured to provide a number of poles, usually for a 3-Phase supply. However, instead of containing Rotor bars, the Rotor has magnets mounted on, or embedded in, the laminations. These magnets, which are often made from rare earth elements (neodymium or ... The actual power capacity of permanent magnet synchronous machine for electric vehicles is usually limited by rotor temperature, ... Usually, measuring the temperature of the rotor permanent magnet is very difficult by equipping sensors to rotate the body directly. Some common techniques include slip rings, ...2. All electro-magnetic generators need magnetic field to induce electric current. This is called excitation. Some generators use permanent magnets to create magnetic field. usually small and low power. simple to build. simple to use. no voltage/power control (only by changing applied speed/torque)Apr 1, 2023 · The rotor spinning at high speed generates a large tensile stress. Once the yield strength of the permanent magnet (PM) is exceeded, the permanent magnet will be broken. Therefore, a high-strength sleeve must be installed outside the permanent magnet [3, 4]. Many researchers have conducted extensive study on rotor strength analysis of HSPMSM ... For permanent-magnet (PM) machines, only specific stator MMF harmonic, known as working harmonic, interacts with the PM field to produce continuous electromagnetic torque . Lower and higher order stator MMF spatial harmonics rotating at different speeds to the rotor, will bring about unwelcome effects, such as eddy current …1 Introduction. Flux-switching permanent-magnet (FSPM) motors have advantages such as high-power and -torque density, high efficiency and simple and robust mechanical structure in the rotor [1-4].These motors have bipolar flux linkage and sinusoidal back-electromotive force (EMF) [].In FSPM motors, because of the placement of …Sep 17, 2020 · Differently from the surface-mounted permanent magnet (PM) synchronous motors, there is an asymmetry of the reluctance between the d-axis and the q-axis, in which saliency can be used to produce reluctance torque in addition to the magnet torque, thus improving the efficiency. In addition, the IPMSMs provide more rotor robustness as magnets are ... Coaxial counter-rotating propellers have been widely applied in ships and helicopters for improving the propulsion efficiency and offsetting system reactive torques. Lately, the counter-rotating concept has been introduced into the wind turbine design. Distributed wind power generation systems often require a novel approach in generator …For the high-frequency permanent magnet electrical machine, a reasonable mechanical aspect design is crucial to meet its stability and reliability. This study focuses on the accurate modelling and analysis of the natural frequencies and modes of the rotor assembly for a designed and manufactured 100 kW 32,000 r/min motor.Nov 27, 2021 · In this study, an analytical model is established to efficiently compute the magnetic field and unbalanced magnetic pull (UMP) in axial-flux permanent-magnet motors (AFPMMs). The effects of stator slotting, end effect, and rotor eccentricity on the magnetic field and forces were investigated. Static and dynamic eccentricities are analyzed and considered in the model. An effective function of ... External rotors of “outrunner” type. Rotors with additional bandage (Polyglas, Kevlar, carbon) Rotors with protecting sleeve. Contact us. Jan Kratochvil ml. +420 607 570 823 [email protected]. We will be happy to cooperate on development and manufacturing of rotors with permanent magnets, please contact our specialist. Leave …A high-speed (HS) permanent magnet (PM) synchronous motor (HSPMSM) with a carbon fiber-reinforced plastic (CFRP) protective sleeve in the surface-mounted rotor was explored in this study.Summary. PM (Permanent Magnet) Type: uses permanent magnets, moderate torque, low to mid-speed. VR (Variable Reluctance) Type: toothed rotor/stator, low torque, mid to high speed. Hybrid Type: combines permanent magnets and teeth, good combination of torque and speed.2.2 External rotor permanent magnet motor rotor air gap magnetic field When the motor is running at no load, the air gap magnetic field is provided by the permanent magnet alone. The generated magnetic field rotates together with the rotor and the rotational speed is synchronous speed.This paper presents a design method of the basic model of high-speed surface-mounted permanent magnet synchronous motor (SPMSM) comprehensively considering the mechanical and electromagnetic properties based on the subdomain method. In the rotor design stage, the mechanical stresses of the permanent magnet …A double-sided permanent magnet rotor with a single stator [2, 3] can offset the axial attraction and increase the output power at the cost of an increased weight. The double-sided permanent magnet rotor design can also reduce bearing wear and noise problem compared with a single-sided structure, which thus increases the generator …Permanent Magnet Rotors. Magnetic motor rotor, which is formed by magnetic steel, metal shaft or metal shell. According to detailed application situation, the …The demagnetization of rotor permanent magnet is described in terms of rotor offset caused by demagnetization, demagnetization angle, decrease of air-gap MMF at the demagnetization …1 Introduction. Flux-switching permanent-magnet (FSPM) motors have advantages such as high-power and -torque density, high efficiency and simple and robust mechanical structure in the rotor [1-4].These motors have bipolar flux linkage and sinusoidal back-electromotive force (EMF) [].In FSPM motors, because of the placement of …In order to improve the performance of synchronous motors, especially in dynamic-transient conditions, induction damper cages are usually used in the rotor structure. In this paper, a new hybrid structure of an axial-flux motor is proposed, which uses a permanent magnet (PM) rotor and an unpaired induction damper cage with …The SPMSM has the permanent magnets fixed on the surface of the rotor leading to a symmetrical radial air-gap reluctance path between the rotor and the stator core. The IPMSM has the permanent magnets inserted inside the rotor core leading to a non-symmetrical radial air-gap reluctance path between the rotor and the stator core. In order to address these issues, a 2-DOF surface permanent magnet spherical motor with a new mechanical design for the movement of the rotor with a large tilt angle of ±45° was designed, simulated, produced and tested in this paper. The motor consisted of a 4-pole permanent magnet rotor and a 3-block stator with 18 coils.Since the pole arc coefficient of the rotor permanent magnet is 0.5, according to Ref. 28, the magnetomotive force generated by the permanent magnet is equal to that generated by the adjacent FMP.Aug 17, 2022 · For high-speed permanent magnet machines (HSPMMs), two different rotor structures are widely used: surface-mounted permanent magnet (SPM) and interior permanent magnet (IPM). The two different rotor structures have a large impact on the comprehensive performance in multiple physical fields of HSPMMs, including mechanical stress, electromagnetic characteristics, and temperature distribution ... High-speed or ultra-high-speed permanent magnet synchronous motors (PMSMs) have a strong trend of application in modern industry due to those simple structures and high power density. 1,2 For high-speed motors or generators, the rotor speed is normally above 30,000 r/min even may exceed 100,000 r/min. Designs of such high …Permanent magnets generate a rotor magnetic field that creates a sinusoidal rate of change of flux based on the rotor angle. For the axes convention, when you set the Rotor angle definition parameter to Angle between the a-phase magnetic axis and the d-axis, the a -phase and permanent magnet fluxes align when the rotor mechanical angle, θr, is ...

Jun 23, 2022 · The rotor overtemperature caused by losses is one of the important issues for the high-speed electrical machine. This paper focuses on the rotor loss analysis and CFD-thermal coupling evaluation for 105 kW, 36,000 r/min HSPMSM. Three types of sleeve materials as carbon-fiber, Titanium alloy, and stainless steel are introduced in this paper, researching the effects of sleeve conductivity ... . Sellers funeral home and cremation services obituaries

permanent magnet rotor e1655961736623.jpeg

This paper presents a design method of the basic model of high-speed surface-mounted permanent magnet synchronous motor (SPMSM) comprehensively considering the mechanical and electromagnetic properties based on the subdomain method. In the rotor design stage, the mechanical stresses of the permanent magnet …The rotor overtemperature caused by losses is one of the important issues for the high-speed electrical machine. This paper focuses on the rotor loss analysis and CFD-thermal coupling evaluation for 105 kW, 36,000 r/min HSPMSM. Three types of sleeve materials as carbon-fiber, Titanium alloy, and stainless steel are introduced in this paper, …Synchronous motor. Miniature synchronous motor used in analog clocks. The rotor is made of permanent magnet. Small synchronous motor with integral stepdown gear from a microwave oven. A synchronous electric motor is an AC electric motor in which, at steady state, [1] the rotation of the shaft is synchronized with the frequency of the supply ... 2.1 Electrical Characteristics. The equivalent circuit of a PMDC motor is shown in Fig. 1. The supply voltage and the current are given. The circuit consists of an induced voltage (Vi) in series with an armature resistor (Rarm) and inductance (Larm). The rotation of the ux generates the induced voltage. 1 Introduction. Over the past decades, the development of the power train with simple structure and high reliability has always been a hot topic in academic research [].Traditional power train with DC motor with double rotor has the shortcomings of poor efficiency and excessive noise [2, 3].Compared with DC motor, permanent magnet …The fundamental operation of a permanent magnet motor is like most electric motors; the outer stator holds windings of coils fed by a power source, and the rotor freely rotates based on the forces imparted by the stator coils. Many of the same basic principles for induction motors hold true for permanent magnet motors, and more information can ...Based on the complex structural characteristics of permanent magnet-assisted synchronous reluctance motors (PMA-SynRMs), this paper proposes a multi-objective optimization design method for the motor using a composite algorithm. Firstly, the power density, electromagnetic torque, cogging torque, and torque fluctuation coefficient …Brushless DC electric motor. The motor from a 3.5 in floppy disk drive. The coils, arranged radially, are made from copper wire coated with blue insulation. The rotor (upper right) has been removed and turned upside-down. The grey ring inside its cup is a permanent magnet. This particular motor is an outrunner, with the stator inside the rotor.1 Introduction. Flux-switching permanent-magnet (FSPM) motors have advantages such as high-power and -torque density, high efficiency and simple and robust mechanical structure in the rotor [1-4].These motors have bipolar flux linkage and sinusoidal back-electromotive force (EMF) [].In FSPM motors, because of the placement of …1 Introduction. Nowadays, high-speed surface-mounted permanent magnet synchronous machines (SPMSMs) are becoming more and more common due to their simple structure, high-power density and high efficiency [1-3].The rare-earth permanent magnets (PMs) are widely applied in the high-speed SPMSMs owing to their high …This study performs a dynamic modeling and analysis of the axial uniform demagnetization rotor of a motor to investigate the demagnetization peculiar for permanent magnet synchronous motor (PMSM). First, the air-gap change in the motor is analyzed by constructing a dual coordinate system of stator and rotor, and the unbalanced magnetic …1 Introduction. Nowadays, high-speed surface-mounted permanent magnet synchronous machines (SPMSMs) are becoming more and more common due to their simple structure, high-power density and high efficiency [1-3].The rare-earth permanent magnets (PMs) are widely applied in the high-speed SPMSMs owing to their high …2. All electro-magnetic generators need magnetic field to induce electric current. This is called excitation. Some generators use permanent magnets to create magnetic field. usually small and low power. simple to build. simple to use. no voltage/power control (only by changing applied speed/torque).

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