Generator device of electrical energy with permanent magnets, particularly for the supply of electrical loads and/or batteries of vehicles

Abstract

The generator device of electrical energy with permanent magnets, particularly for the supply of electrical loads and/or batteries of vehicles, connectable to at least a driving shaft of a motor, comprises: a rotor element rotating around an axis of rotation; a stator element contained inside the rotor element, or containing the rotor element, and coaxial to the rotor element, the stator element having a plurality of stator slots; a plurality of stator windings of a conductive material arranged at each of the stator slots and connected to a power supply line; a plurality of permanent magnets having a first side associated with the rotor element and a second side facing the stator element; wherein the permanent magnets are associated with the rotor element in a configuration of the Halbach array type to define a magnetic coupling to the stator windings wherein the magnetic field flow at the second side of each of the permanent magnets is substantially greater than the flow of the magnetic field at the first side of each of the permanent magnets.

Claims

1. A permanent magnet motor generator, particularly for a supply of electrical loads and/or batteries of vehicles, connectable to at least a driving shaft of a motor, comprising: at least a rotor element rotating around an axis of rotation; at least a stator element contained inside said rotor element, or containing said rotor element, and coaxial to said rotor element, said stator element having a plurality of stator slots; a plurality of stator windings of a conductive material arranged at each of said plurality of stator slots and connected to a power supply line; a plurality of permanent magnets having at least a first side associated with said rotor element and at least a second side facing said stator element; detection means comprising Hall probes for detecting an intensity of a magnetic field flow of said permanent magnet motor generator, the detection means being operatively connected to an inverter device, with said detection means being adapted to provide a value relating to an angular position of said rotor element with respect to said stator element; and an air gap that is disposed between the stator element and the rotor element, the air gap comprising at least one of (i) air and (ii) a dielectric material, and the air gap being configured to allow for rotation of the rotor element with respect to the stator element, wherein said plurality of permanent magnets are associated with said rotor element in a configuration of a Halbach array type to define a magnetic coupling to said plurality of stator windings, wherein a magnetic field flow at said second side of each of the permanent magnets is substantially greater than a flow of a magnetic field at said first side of each of the plurality of permanent magnets, wherein said permanent magnet motor generator is operatively connected to said driving shaft, wherein said stator element is connected to a poly-phase power supply line, having at least three supply phases, which is connected to an inverter device, wherein said inverter device is adapted to activate rotation and adjustment of a rotation speed of said driving shaft, wherein said detection means are associated with the stator element so that an angular distance between each of the Hall probes with respect to the stator element is dependent on a number of the plurality of stator slots, a number of phases, and a number of the plurality of permanent magnets associated with the rotor element, and wherein the Hall probes provide said inverter device with said angular position of said rotor element with respect to said stator element, and depending on said angular position, said inverter device is adapted to regulate the poly-phase power supply line connected to said stator element during a start-up phase of the permanent magnetic motor generator.

2. A permanent magnet motor generator, particularly for a supply of electrical loads and/or batteries of a motorcycle, connectable to at least a driving shaft of a motor, comprising: at least a rotor element rotating around an axis of rotation; at least a stator element contained inside said rotor element, or containing said rotor element, and coaxial to said rotor element, said stator element having a plurality of stator slots; a plurality of stator windings of a conductive material arranged at each of said plurality of stator slots and connected to a power supply line; and a plurality of permanent magnets having at least a first side associated with said rotor element and at least a second side facing said stator element, wherein said plurality of permanent magnets are associated with said rotor element in a configuration of a Halbach array type to define a magnetic coupling to said plurality of stator windings, wherein a magnetic field flow at said second side of each of the permanent magnets is substantially greater than a flow of a magnetic field at said first side of each of the plurality of permanent magnets, wherein said permanent magnet motor generator is operatively connected to said driving shaft, wherein said stator element is connected to a poly-phase power supply line, having at least three supply phases, which is connected to an inverter device, wherein said inverter device is adapted to activate rotation and adjustment of a rotation speed of said driving shaft, wherein the permanent magnet motor generator is configured to provide high breakaway torque during start-up while maintaining low overall dimensions, wherein the permanent magnet motor generator is configured to reduce magnetic induction in said rotor element and increasing magnetic induction to the stator element and to an air gap without requiring any increase in outer dimensions and overall dimensions of the rotor element, and wherein the permanent magnet motor generator is configured to reduce losses due to dissipation in the rotor element and increase magnetic induction to the air gap which permits reducing a thickness of the stator element and the overall dimensions of the permanent magnet motor generator and to increase performance of the permanent magnet motor generator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other characteristics and advantages of the present invention will become more evident from the description of a preferred, but not exclusive, embodiment of a generator device of electrical energy with permanent magnets, particularly for the supply of electrical loads and/or batteries of vehicles, illustrated by way of an indicative, but non-limiting example in the accompanying drawings, wherein:

(2) FIG. 1a is a sectional view of a device of known type in a first embodiment;

(3) FIG. 1b is a sectional view of a device of known type in a second embodiment;

(4) FIG. 2 is a sectional view of the device according to the invention in a first embodiment;

(5) FIG. 3 is a schematic representation of a detail of the device according to the invention;

(6) FIG. 4a illustrates the radiation diagram of the magnetic field flow of the device according to the invention;

(7) FIG. 4b illustrates the radiation diagram of the magnetic field flow of a device of known type;

(8) FIG. 5 graphically illustrates the pattern of the magnetic induction quantity B.sub.z according to the distance x;

(9) FIG. 6 is a sectional view of the device according to the invention in a second embodiment;

(10) FIG. 7 illustrates a comparative graph between the performance obtained by a device of known type, in which the permanent magnets are arranged in a classic configuration, and by the device according to the invention, in which the permanent magnets are arranged in the Halbach configuration;

(11) FIG. 8 illustrates a comparative table of the results obtained by a device of known type, in which the permanent magnets are arranged in a classic configuration, and by the device according to the invention, in which the permanent magnets are arranged in the Halbach configuration.

EMBODIMENTS OF THE INVENTION

(12) With particular reference to such figures, globally indicated with reference numeral 1 is a generator device of electrical energy with permanent magnets, particularly for the supply of electrical loads and/or batteries of vehicles.

(13) The device 1 is connectable to a driving shaft of an engine, e.g. of the type of an internal combustion engine, and comprises: a rotor element 2 rotating around a relevant axis of rotation; a stator element 3 contained inside the rotor element 2, or containing the rotor element 2, coaxial to the rotor element 2 and having a plurality of stator slots 4; a plurality of stator windings 5 made of a conductive material arranged at each of the stator slots 4 and connected to a power supply line; a plurality of permanent magnets 6 having a first side 7 associated with the rotor element 2 and a second side 8 facing the stator element 3.

(14) The stator element 3 is composed of a lamellar pack made of ferromagnetic material and the rotor element 2 is composed of a cap or crown made of ferromagnetic material.

(15) Alternative embodiments cannot however be ruled out wherein the rotor element 2 is made of a material other than ferromagnetic material, e.g., of diamagnetic or paramagnetic material.

(16) In the embodiments shown in the illustrations, the stator element 3 is contained inside the rotor element 2 and these are coaxial to one another.

(17) More in detail, between the stator element 3 and the rotor element 2 is an interspace containing air or dielectric material, commonly known as air gap, such as to allow the rotation of the rotor element 2 with respect to the stator element 3.

(18) Alternative embodiments cannot however be ruled out wherein the rotor element 2 is contained inside the stator element 3 and these are coaxial to one another.

(19) According to the invention, the permanent magnets 6 are associated with the rotor element 2 in a configuration of the Halbach array type to define a magnetic coupling to the stator windings 5 wherein the flow of the magnetic field at the second side 8 of each of the permanent magnets 6 is substantially greater than the flow of the magnetic field at the first side 7 of each of the permanent magnets 6.

(20) Within the scope of this treatise, with the expression Halbach array is meant the particular configuration wherein a plurality of permanent magnets 6 are arranged in contact with one another so as to strengthen and intensify the magnetic field along one face of the array, which in the embodiments shown in the illustrations is substantially defined by the second sides 8 of the permanent magnets 6 turned towards the stator element 3, and at the same time cancel by interference the magnetic field which develops on the opposite face, substantially defined by the first sides 7 of the permanent magnets 6.

(21) In a first embodiment shown in FIG. 2, the device 1 is a generator with permanent magnets wherein the permanent magnets 6 are arranged in the Halbach array configuration.

(22) More in detail, FIG. 3 illustrates the arrangement and the orientation of the North and South poles of the permanent magnets 6 which are associated with the rotor element 2 so as to achieve the Halbach array configuration.

(23) By way of example and explanation, FIG. 4a illustrates the radiation diagram of the magnetic field in the event of the permanent magnets 6 being arranged in the Halbach array configuration; while FIG. 4b illustrates the radiation diagram of the magnetic field in the event of the permanent magnets 6 being arranged in a classic configuration with alternated polarities.

(24) FIG. 5 graphically illustrates the magnetic induction pattern according to the intensity of the magnetic field.

(25) More in detail, the magnetic induction quantity is indicated by B.sub.z, the distance quantity is indicated by x while the pole pitch quantity is indicated by I.sub.a.

(26) In particular, it can be seen that the magnetic induction B.sub.z according to the distance x has a substantially sinusoidal pattern, different with respect to the pattern obtained for the devices of known type.

(27) In a second embodiment shown in FIG. 6, the device 1 is a motor generator with permanent magnets.

(28) More in detail, the device 1 is operatively connected to the driving shaft and the stator element 3 is connected to a poly-phase power supply line, having at least three supply phases, in turn connected to an inverter device.

(29) In particular, the inverter device is an electronic device adapted to rectify the alternating current supplied by the device 1 to supply the battery and/or the electrical loads when it operates as a generator, after the internal combustion engine is started; vice versa the inverter device is adapted to convert the direct current into poly-phase alternating current to supply the device 1 during the start-up phase wherein the device itself operates as a brushless motor to start the internal combustion engine.

(30) In such a second embodiment, the device 1 comprises detection means 9 of the intensity of the flow of the magnetic field, generated by the device itself, which are operatively connected to the inverter device to activate the rotation and the regulation of the rotation speed of the driving shaft during the start-up phase.

(31) The detection means 9 are adapted to provide a value relating to the angular position of the rotor element 2 with respect to the stator element 3.

(32) Preferably, the detection means 9 are of the type of one or more Hall probes. Advantageously, the Hall probes 9 are associated with the stator element 3 so that the angular distance between each Hall probe 9 with respect to the stator element 3 is dependent on and related to the number of stator slots 4, to the number of phases and to the number of permanent magnets 6 associated with the rotor element 2.

(33) More in detail, the Hall probes 9 provide the inverter device with the angular position of the rotor element 2 with respect to the stator element 3 and, depending on such angular position, the inverter device is adapted to regulate the poly-phase supply of the stator element 3 during the start-up phase of the device 1.

(34) FIGS. 7 and 8 illustrate, by way of example, the results relating to the performance achieved by the device 1 in the event of the permanent magnets 6 being arranged in the classic configuration with the North and South polarities alternated the one with the other and in the event of the permanent magnets 6 being arranged in the Halbach array configuration.

(35) In particular, both the devices 1, when compared, have the same outer diameter and diameter at air gap as well as the same number of rotor poles (in this specific case 16 rotor poles) and the same number of stator slots 4 (in this specific case 18 stator slots) with three-phase stator windings 5 with star connection.

(36) The results shown in FIGS. 7 and 8 refer to the performance obtained by measuring the current at the output of each of the devices 1 connected to a three-phase supply line and to a constant voltage of 14 V.

(37) More in detail, from the table in FIG. 8, it can be seen that in the case of Halbach array configuration of the permanent magnets 6, a reduction is obtained in the phase resistance which consequently leads to a reduction of losses in copper.

(38) This characteristic is particularly important in the event of the device 1 being a generator with permanent magnets combined with a shunt type regulator.

(39) The same results in terms of efficiency and indicated overall dimensions can also be obtained in the event of the device 1 being a motor generator with permanent magnets.

(40) It has in fact been ascertained that the described invention achieves the intended objects and in particular the fact is underlined that the device made this way permits reducing the magnetic induction in the rotor element and increasing the magnetic induction to the stator element and to the air gap without any increase in the outer dimensions and overall dimensions of the rotor element.

(41) This is therefore followed by a reduction in losses due to dissipation in the rotor element and by a considerable increase in magnetic induction to the air gap which permit reducing the thickness of the stator element, and therefore the overall dimensions of the device, as well as increasing the performance of the device itself.

(42) In other words, the reduction in thickness of the stator element, the magnetic flow in the stator element itself being equal, permits reducing the length of the stator windings and at the same time results in a reduction of the electrical resistance of the stator winding and therefore of the losses by Joule effect in copper.