RO132797A2 - Electro-thermal generator with axial-flux permanent magnets - Google Patents

Abstract

The invention relates to an electro-thermal generator with permanent magnets with axial magnetic field flux, meant to be used for converting mechanical rotation energy into electric power and heat. According to the invention, the generator comprises a rotor and a stator, where the rotor consists of two disc-shaped magnetic cores (1) made of massive magnetic steel, fixed on a shaft (5) and to each other, where one or several pairs of permanent magnets (2), alternately magnetized in axial direction, are mounted on each of them, the stator consisting of a toroidal pipe (3) of magnetic steel around which several coils (4) made of a thin insulated conductor are arranged in connection to one another, so as to form a system of windings, where both the coils (4) and the stator pipe (3) are embedded in an epoxy resin (11), the rotary magnetic field developed as a consequence of the rotation of the permanent magnets (2) generating induced currents in the stator pipe (3), most of the heat released from losses dissipated in the pipe (3) and the Joule losses in the coils (4) being taken over by a heating medium (6) which enters the thermal circuit under pressure, in cold state, through an orifice (7) and gets out heated, through another orifice (8).

Description

DESCRIPTION

The invention relates to an electrothermal generator with permanent magnets with axial flow used for the conversion of the mechanical energy of rotation into electricity and heat.

The specialized literature presents electric generators with axial magnetic flux intended for the production of electricity through the conversion of mechanical rotational energy. An example of such a generator is presented in the paper: F. Marignetti, R. Di Stefano, Y. Coia, “Analysis of Axial Flux PM Machines Including Stator and Rotor Core Losses Proc. of the 34 ^th IEEE Annual Conference of Industrial Electronics, (IECON 2008), pp. 2035 2040, 2008. This study presents an axial magnetic flux generator used for the conversion of mechanical energy into electricity.

This solution has the following disadvantages:

- Relatively low energy efficiency (the main categories of losses being Joule losses from windings, losses in iron, losses through swirling currents in magnets, mechanical losses),

- Relatively large dimensions.

The invention, by the proposed technical solution, removes the disadvantages of the solution presented in the above work by the fact that an important part of the losses dissipated in the machine is recovered by cogeneration and transformed into useful thermal energy, the proposed electrothermal generator having an overall higher conversion efficiency and dimensions. reduced size.

By applying the invention, several advantages are obtained such as:

- Ensuring a process of converting the mechanical energy of rotation into electric and thermal energy through cogeneration, at a high overall efficiency (electrical and thermal), higher than the conventional electric generators;

- Smaller dimensions of dimensions as the electrical and magnetic demands for which the generator is designed and realized can be much higher than the conventional electric generators;

- High energy density per volume unit;

- The proposed solution can be used in wind systems integrated in energy efficient buildings, possibly in combination with other renewable energy sources (eg solar thermal panels, heat pumps, photovoltaic panels, etc.);

- Low unit costs of the energy supplied (electric and thermal);

- Simple and cheap management of heat and electricity.

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The following is a non-limiting example in relation to Figures 1-5 which represents:

- Figure 1, Main diagram regarding the operation of the electrothermal generator as a converter of the mechanical energy of rotation in electricity and heat;

- Figure 2, Component parts of the electrothermal generator with axial magnetic flux, without highlighting the housing and the resin in which the stator is embedded, respectively without highlighting the details regarding the shaft dimensions;

- Figure 3, 3D view on the component parts of the electrothermal generator with axial magnetic flux, without highlighting the stator coils, the housing and the resin in which the stator is embedded, respectively without highlighting the details regarding the shaft dimensions;

- Figure 4, Axial section through the electrothermal generator;

- Figure 5, 2D view of the electrothermal generator.

The ElectroTermic generator (GET) with permanent axial flow magnets allows the conversion of the rotational mechanical energy into electricity and heat (Figure 1).

The GET is composed of a fixed part called a stator and a movable part called a rotor, the two parts being housed by the housing 9.

The generator rotor is composed of two discoidal magnetic cores 1 made of solid magnetic steel, one or more pairs of permanent magnets being mounted on each of them 2. The two discoidal magnetic cores 1 are fixed to each other by means of screws 14, respectively fixed. compared to shaft 5 made of steel, all these components rotating in solidarity under the action of mechanical rotational energy. Permanent magnets 2 are magnetized alternately (alternating sequence of North-South-North-South type) in axial direction.

The generator stator (fixed part) is made of a toroidal tube 3 made of magnetic steel, around which the coils 4 are arranged, the coils and the stator tube being embedded in an epoxy resin 11. The coils 4 are made of insulated thin conductor. and are connected in

9 series / parallel and can form a single-phase, two-phase, three-phase or polyphase winding system (depending on the number of phases chosen). The electricity produced by the generator is transmitted to the load through the cables 15 to which the ends of the windings of the generator are connected.

Through the magnetic steel pipe 3 circulates the thermal agent 6 which enters under pressure (by pumping) in the cold state circuit through the hole 7 and exits the hot state circuit through the hole 8 (Figure 2).

following the rotation of the permanent magnets 2 which move in solidarity with the magnetic cores 1 and the shaft 5, a rotating magnetic field is produced which determines the occurrence of induced voltages in the coils 4 of the 2017 00061

06/02/2017 to the stator, just like in the case of a synchronous electric generator with flow

Λ axial magnetic that will produce useful electrical energy. At the same time the rotating magnetic field will determine the occurrence of induced currents in the walls of pipe 3, which by Joule effect will determine its heating. Much of the heat developed as a result of losses through turbulent currents and hysteresis in pipe 3, respectively a large part of Joule losses dissipated in coils 4 as a result of the passage of electric current through conductors will be taken by forced convection by the heat agent 6 what goes through the pipe 3.

The GET stator is fixed inside the housing 9, made up of two parts fixed by means of the clamping ears 12, fastened by the screws 13 (Figure 4 and Figure 5). The housing is centered on the shaft 5 by ball or roller bearings 10 (Figure 4).

The flow rate of the liquid thermal agent 6 must be controlled so that its temperature is kept within certain limits that prevent the generator from overheating which can affect the insulation system and can irreversibly demagnetize the permanent magnet 2. The heat taken by the thermal agent 6 and discharged through the hole 8 will be used for other useful purposes such as preheating of domestic water, heating of premises, etc.

By the forced cooling provided by the thermal agent the electrical and magnetic demands (the current density in the stator coils 4 and the magnetic induction in the stator tube 3) for which the GET is designed and realized can be significantly higher than in the usual electric generators with axial flow with permanent magnets. , resulting in a more compact machine construction. Also, by recovering a large part of the Joule losses and the iron losses through the heat agent 6, the energy efficiency of the GET will be superior to the classic cars.

The GET configuration can take several constructive variants, such as:

- variant with an internal toroidal stator and two rotor discs face to face (variant described above),

- variant with a single rotor disk face to face with a toroidal stator,

- variant with an internal rotor and two external toroidal stators,

- the variant with several rotors and stators mounted on the same axis to obtain a higher power of the system.

The electricity produced by GET and transmitted to the load via cables 15 can be injected into the power grid through a specialized electronic converter, can be charged to a consumer-owned network or stored.

Claims (4)

An electrothermal generator with permanent flux magnets with axial flow designed to convert the mechanical energy of rotation into electric energy and heat, consisting of a movable part called a rotor and a fixed part called stator, separated by an air layer called air gap, the rotor being composed of - one or more pairs of permanent magnets (2) alternately magnetized in the axial direction, the magnets (2) being mounted on the inner faces of two discoidal magnetic cores (1) made of solid magnetic steel and fixed to the shaft (5) (14), the stator being in turn being made up of a toroidal pipe (3) made of magnetic steel around which are disposed several coils (4) connected in series / parallel forming the winding system of the generator can be of the monophasic, biphasic, triphase or polyphase type (depending on the chosen configuration), the coils (4) being made of in an insulated thin conductor, inducing electromagnetic voltages in the coils as in the case of a conventional synchronous electric generator with axial magnetic flux with permanent magnets, the power generated by the generator being transmitted to the load through the cables (15) to which the ends of the winding system of the generator, both the coils (4) and the stator pipe (3) being embedded in the epoxy resin (11), the rotating magnetic field resulting from the rotation of the permanent magnets (2) giving rise to induced currents in the stator pipe most of the heat developed as a result of the losses in the stator pipe (3) and the Joule losses in the coils (4) are taken over by the cold (cold-pressure) thermal agent (6) through the orifice 7) leaving it in the hot state through the orifice (8), the rotor and stator of the generator being housed by a housing (9) made of two identical metallic parts fixed by means of the clamping eyes (12) tightened by means of the screws (13), the carcass (9) being centered on the shaft (5) by means of the bearings (10). An electrothermal generator with axial flow permanent magnets according to the preceding claims with the particularity that the rotor consists of a single discoidal magnetic core (1) with permanent magnets (2) mounted on one side of the rotor core. An electrothermal generator with permanent magnet with axial flow according to the claims in item 1 with the particularity that the equipment consists of two outer stators identical to the one described above and an inner rotor made of a single magnetic discoidal core (1) with magnets permanent (2) mounted on both sides of the rotor core. An electrothermal generator with permanent magnet with axial flow according to the claims in item 1 with the particularity that the equipment is made up of several stator-rotor groups mounted face to face on the same shaft in order to obtain a total (electrical and thermal) power.