FR3112252A1 - Synchronous electrical machine equipped with a mechanical switch - Google Patents

Abstract

Mechanical switch (40) for an electrical machine (1) suitable for supplying by a polyphase current system comprising q phases, with q positive integer strictly greater than 1, a rotor (3) of a rotating electrical machine having 2*p visible magnetic poles and a magnetic reduction ratio G, comprising: - a commutator (41) mobile in rotation around an axis (X) of the electrical machine, with an elementary pattern equal to 2*π/(G*p*q), - at the at least one pair of brushes with radial extension, a positive brush (45) and a negative brush (46), capable of rubbing on the commutator (41), fixed in rotation, each defined on an angular sector, capable of being connected to one and the same vehicle battery (B), characterized in that the mechanical collector (41) comprises G*p*q, with integer G, conductive blades (60) succeeding each other circumferentially, each blade (60) being defined on a sector angular, the adjacent blades being isolated from each other, the blades being distributed in q gro upes (a', b', c'), all the blades (60) of the same group being electrically connected together, the q groups being circumferentially alternated, and in that the brushes (45, 46) of the same pair are circumferentially offset from each other by [(2k+1)*2*π]/(2*G*p), k being a natural number. Figure for abstract: Fig. 2

Description

Synchronous electric machine equipped with a mechanical commutator

The present invention relates to a mechanical switch for supplying a rotating electrical machine by a polyphase current system. The invention also relates to an electric machine equipped with such a switch for a motor vehicle. This electric machine belongs in particular to the fields of variable reluctance machines.

The invention finds a particularly advantageous application in the field of rotating electrical machines such as alternators, alternator-starters, electric motors and reversible machines. The invention also finds particular application in the traction of low-power motor vehicles, in particular between 4kW and 25kW, for example between 4kW and 8kW, for example between 15kW and 25kW.

The invention can thus advantageously be implemented in particular with low-power four-wheeled electric vehicles (“microcars”), two-wheeled vehicles of the motorcycle type, or heavy quadricycles.

It is known from the prior art of direct current electrical machines, used in particular in motor vehicle starters but also to propel a vehicle. These machines equipped with a stator, here the inductor, comprising several permanent magnets or wound poles (electromagnets) and a rotor, here the armature, comprising conductors forming the winding of the rotor. The armature comprises a mechanical commutator fitted with blades on which brushes rub to supply direct current to the armature.

The brush/collector assembly forms a mechanical commutator which allows the mechanical self-piloting of the winding power supply. Each change in the angular position of the armature corresponds, thanks to the arrangement of the angular position of the blades and the brushes, to a new supply of the winding. The positioning of the brushes and the commutator is fixed by the angular position of the field poles.

The main drawback of these machines lies in the sudden variations of the magnetic energy at each current switching in the conductors, in particular in the armature sections of the winding. Current switching causes excessive brush wear. Furthermore, the performance of such machines is insufficient for an application in the traction chain of a motor vehicle in comparison with polyphase synchronous rotating electric machines, in particular three-phase, with synchronous alternating current.

Such a polyphase synchronous machine conventionally comprises a mobile rotor in rotation around an axis and a fixed stator surrounding the rotor. In alternator mode, when the rotor is rotating, it induces a voltage in the stator which transforms it into electric current to then supply the electrical consumers of the vehicle and recharge the battery. In motor mode, the stator is electrically powered and creates a rotating magnetic field then a torque relative to the field poles, driving the rotor in rotation for example to start the heat engine. These machines have a clear advantage in terms of volume performance compared to DC machines.

Such a machine conventionally comprises a shaft, secured to the rotor, one rear end of which carries slip rings belonging to a commutator. Brushes are arranged to rub on the slip rings. The brush holder is connected to a voltage regulator for use in alternator mode.

The stator comprises a body consisting of a stack of thin laminations forming a crown, the inner face of which is provided with slots open inwards to receive a winding comprising phase windings connected together, for example, in a star or in a triangle . These windings pass through the notches of the body of the stator and form buns projecting on either side of the body of the stator. The phase windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. The winding is electrically connected to an electronic assembly by an input and an output. Unlike DC electrical machines, the windings are open.

The electronic assembly includes power electronic modules for controlling the power supply to the winding phases. The switching here is electronic and requires semiconductor inverters. For example, in the case of electric traction by a three-phase synchronous machine, the phases of the winding are conventionally supplied by an electronic inverter comprising 6 stages of MOSFET type power transistors, the control of which requires the rotor position data obtained at the using different position sensors. In the case of a double-three-phase power supply, 6 inverter arms each with MOFSETs are required, twice as much as in the case of a three-phase power supply. The position sensors can be Hall effect in the case of a direct current permanent magnet synchronous machine (“BLDC” in English) whose power supply is slotted. Position sensors can also be of the resolver type, more expensive than Hall effect sensors, in the case of a synchronous machine with alternating current permanent magnets (“BLAC” in English) whose power supply is sinusoidal.

This electronic assembly is expensive. The reliability of semiconductor components in a severe temperature or vibration environment is not optimal due to the fragility of these components. These components are also dependent on materials such as silicon, the supply of which may or may prove to be sensitive.

There is therefore a need to supply electrical machines with a polyphase current system in a less costly and/or less dependent way in terms of power electronics, or even completely independently in terms of power electronics.

• un collecteur mobile en rotation autour d’un axe de la machine électrique, de motif élémentaire égal à 2*π/(G*p*q),
• au moins une paire de balais d’extension radiale, un balai positif et un balai négatif, aptes à frotter sur le collecteur, fixes en rotation, définis chacun sur un secteur angulaire, aptes à être reliés à une même source de tension, notamment une batterie de véhicule,

The invention aims to effectively remedy this drawback by proposing a mechanical switch for an electric machine capable of supplying by a polyphase current system comprising q phases, with q positive integer strictly greater than 1, a rotor of a rotating electric machine having 2*p apparent magnetic poles and a magnetic reduction ratio G , comprising:

• a commutator mobile in rotation around an axis of the electrical machine, with an elementary pattern equal to 2*π/(G*p*q),
• at least one pair of brushes with radial extension, a positive brush and a negative brush, capable of rubbing on the commutator, fixed in rotation, each defined on an angular sector, capable of being connected to the same voltage source, in particular a vehicle battery,

The mechanical switch is characterized in that the mechanical commutator comprises G*p*q, with integer G, with in particular G=5 or G=11, conductive blades succeeding each other circumferentially, each blade being defined on an angular sector, the adjacent blades being insulated from each other, the blades being divided into q groups, all the blades of the same group being electrically connected together, the q groups being alternated circumferentially.

The mechanical commutator is also characterized in that the brushes of the same pair are circumferentially offset from each other by [(2k+1)*2*π]/(2*G*p)], k being a natural number.

Such a power supply is thus more sustainable and less expensive. The performance is also significantly higher than that of a direct current electric machine.

Such a switch allows electrical machines to be supplied by a polyphase current system without an electronic converter, so that the number of power electronic components and the associated cost is greatly reduced, or even eliminated. Such an autopilot power supply also makes it possible to dispense with a rotor position sensor.

According to one aspect of the invention, the angular offset between the brushes is from center to center, that is to say between the median planes of each brush. A broom can have a substantially parallelepipedal shape. According to one aspect of the invention, the brushes can always be in contact with a blade. A brush may comprise a radially inner cylindrical surface in contact with the commutator, in particular with the blades.

According to one aspect of the invention, the number of pairs of brushes is between 1 and G*p. For example, the number of pairs of brushes can be equal to one or two for a machine with two pairs of apparent poles with a magnetic reduction ratio G equal to 1. All the pairs of brushes rub on the same blades. According to the invention, the number of brushes is therefore even.

According to one aspect of the invention, the collector has G*p*q passages from one type of blade to another. The type of a slide is defined by its membership in one of the slide groups.

According to one aspect of the invention, the collector has G times the same sequence of blades.

According to one aspect of the invention, the blades all have the same angular sector and/or the axial dimension. In particular, all the blades are identical. The blades may not be offset axially. The blades can be copper. The blades can have a radial thickness of between 1mm and 3mm, for example 2mm. This thickness makes it possible to reduce the current volume density in the blades. The blades can have an axial dimension between 8mm and 12mm, for example 10mm. According to the invention, the collector has a single circumferential arrangement of conductive blades around the axis.

According to one aspect of the invention, the collector comprises a skeleton, of revolution around the axis of the electric machine, to hold the blades in position. The skeleton can be made of an electrically insulating material, for example plastic. The skeleton can be in one piece. The skeleton may comprise radial openings, in particular G*p*q openings receiving the blades. The skeleton can be overmolded on the blades. The skeleton may include a central opening for receiving a rotor shaft. The collector may comprise a sleeve disposed in the central opening of the skeleton and adapted to be integral with the rotor shaft. The sleeve is fixed relative to the skeleton. The sleeve is more rigid than the skeleton so as to reinforce the connection between the commutator and the rotor shaft.

According to one aspect of the invention, q can be equal to 3. The switch is thus able to supply an electrical machine according to a three-phase current system.

According to one aspect of the invention, the friction zone between the brushes and the blades can be at a radial distance relative to the axis of between 20 mm and 45 mm, in particular 25 mm, in particular 35 mm.

According to one aspect of the invention, an angular sector on which a given part is defined is the smallest sector which includes the given part in a plane perpendicular to the axis of the machine.

According to another aspect of the invention, the blades of the same group can all be electrically connected to a ring arranged radially inside the blades.

Such a ring makes it possible to pool the electrical connections between the blades of the same group, which simplifies the manufacture of the switch. Within the meaning of the application, the brushes do not rub on the rings but on the blades.

According to another aspect of the invention, a bridge can be provided between each blade and the associated ring. The bridges extend radially from the ring, notably without axial offset from the ring. The bridges and the associated ring are in an interior space of the skeleton while the blades are flush towards the outside to come into electrical contact with the brushes. The blades of the same group, the bridges and the ring form a ring in one piece. The ring and the annulus associated with the blades of group q are said to be of type q.

According to another aspect of the invention, the collector comprises q connecting arms, each being secured to a ring, in particular by welding. Each arm has a free end suitable for being connected to one phase, or to several phases, of the winding of the rotor to supply it or supply them. Each connecting arm emerges, in particular radially, from the skeleton of the manifold through a radial hole formed in the skeleton.

According to one aspect of the invention, the rings of each group can follow one another axially.

This axial juxtaposition favors the compactness of the collector.

According to one aspect of the invention, the bridges of the same type q are offset from the bridges of the other types. The rings can be axially distributed over an axial length of blade.

The bridges can be connected to a central area of the blades or to one end thereof. In particular, when q = 3 (i.e. when the current system is three-phase) the collector comprises three rings, one central and two at the ends surrounding the central ring. The bridges associated with the central ring are connected axially to the center of the blades and the bridges associated with the end rings are connected on the corners of the blades.

Alternatively, the rings can be concentric.

According to one aspect of the invention, each blade can be separated from the two adjacent blades by an inter-blade.

The inter-blade is defined to prevent circumferential contact between two successive blades.

According to one aspect of the invention, the inter-blades can all have the same angular opening.

The angular opening of each blade can thus be equal, in radians, to [2*π- G*q*p*(opening of an inter-blade)]/(G*p*q).

According to one aspect of the invention, the angular opening of an inter-blade is smaller than the angular opening of one of the blades. As a variant, the angular opening of an inter-blade can be greater than the angular opening of one of the blades.

According to one aspect of the invention, the minimum dimension in the circumferential direction between two successive blades, that is to say the circumferential dimension of the inter-blades, is chosen to avoid dielectric breakdown. The minimum dimension can be between 1.6mm and 2.4mm when the switch is powered at 48V.

This dimension of the inter-blades makes it possible to avoid electric arcs between adjacent blades while leaving sufficient space for the blades, which simplifies the manufacture of the skeleton. This dimension of inter-blades can also allow the continuity of the friction between the brushes and the blades.

The minimum radial dimension of the collector is imposed by the number of blades and by the minimum dimension of the inter-blades to be respected.

The angular opening of one of the inter-blades is deduced from the radial distance of the friction zone and the circumferential dimension of this inter-blade.

The angular opening of the blades can be identical to the angular opening of the inter-blades. Each leaf and each inter-blade each extend over 2*π/(2* G*p*q).

According to one aspect of the invention, the inter-blade can be insulating. The inter-blade can be an empty space between two successive blades. The inter-blade may comprise a non-conductive protrusion, in particular formed by the skeleton.

According to one aspect of the invention, one of the inter-blades, in particular each inter-blade, can comprise an isolated blade. The insulated blade is not electrically connected to any other blade. The blade is said to be insulated in opposition to the conducting blades, electrically connected which form the q groups. As a variant, the inter-blades can be connected together forming a group of insulated blades under the same conditions of electric potential.

According to one aspect of the invention, the isolated blades can be fixed on an inter-blade ring. The inter-blade ring can be arranged in the interior space of the skeleton. The inter-blade ring can be radially outside the q-type rings. Insulated slats have a foot inserted into an opening in the inter-slat ring for fixing the insulated slat. The inter-blade ring can include windows for the passage of the bridges between the blades of one of the q groups and the associated ring.

The insulated blade is separated from the conductive blades by interstices. The gaps can measure between 1mm and 5mm in the circumferential direction. The insulated blades are received in radial openings. The collector can then comprise 2*G*p*q blades, the conductive blades being alternated with the insulated blades. The insulated blades are at floating potential.

According to one aspect of the invention, the angular opening of the insulated blades can be between 20 and 50%, in particular between 40% and 50% of the angular opening of the conductive blades.

The insulated blades ensure uniform contact between the commutator and the brushes. Indeed the brushes rub almost continuously on the blades, insulated or conductive.

According to one aspect of the invention, the angular opening of each brush is greater than the angular opening of the inter-blades. Thus, each brush is always in contact with at least one blade. Each brush can be in simultaneous contact with at most two different groups of blades.

According to one aspect of the invention, the overlap rate may be the ratio between the difference between the angular opening of a brush and the angular opening of an inter-blade divided by the elementary pattern of the commutator.

According to one aspect of the invention, the recovery rate can be between between 10% and 55%. This rate of

According to one aspect of the invention, the sum of the angular opening of a brush and the angular opening of a blade can be greater than or equal to 120 electrical degrees and strictly less than 180 electrical degrees.

Within the meaning of the application, the ratio between an electrical degree and a geometric degree is equal to G*p.

Within the meaning of the application, the overlap is the period during which a given brush is in contact with two blades of different groups. During this covering, the brush can thus supply two separate groups of blades simultaneously. The simultaneous supply of two groups of blades for the same brush influences the form of the polyphase current system. The waveform of each phase is changed. The covering makes it possible to supply the rotor according to a polyphase current system, for example slotted, for example quasi-sinusoidal while maintaining the current of the voltage source at a non-zero average value, of the same current sign over time .

According to one aspect of the application, with a fixed commutator (angular opening of the blades and fixed inter-blades), the opening of the brushes can be chosen to obtain different forms of current system. For a given collector, there can therefore be several current systems.

• un commutateur mécanique tel que décrit précédemment,
• un stator fixe en rotation, le stator formant l’inducteur de la machine,
• un rotor mobile en rotation autour de l’axe de la machine électrique, le rotor formant avec le collecteur un induit de la machine, le rotor comprenant :
  1. un arbre de rotor, et
  2. un corps de rotor comprenant :
     1. un paquet de tôles comprenant des tôles empilées axialement, le paquet de tôles comprenant Nr dents rotoriques, le paquet de tôles ayant une pluralité d’encoches d’extension axiale,
     2. au moins un bobinage, le bobinage étant reparti en q phases (a, b, c) alimentées par le commutateur, les phases comprenant des sections de bobinage logés dans les encoches, les sections de chaque phase se succédant circonférentiellement, chaque phase présentant deux extrémités (32).

The invention also relates to an electric machine which comprises:

• a mechanical switch as described previously,
• a stator fixed in rotation, the stator forming the inductor of the machine,
• a rotor mobile in rotation around the axis of the electric machine, the rotor forming with the commutator an armature of the machine, the rotor comprising:
  1. a rotor shaft, and
  2. a rotor body comprising:
     1. a lamination package comprising axially stacked laminations, the lamination package including Nr rotor teeth, the lamination package having a plurality of axially extending slots,
     2. at least one winding, the winding being divided into q phases (a, b, c) supplied by the switch, the phases comprising winding sections housed in the notches, the sections of each phase succeeding each other circumferentially, each phase having two ends (32).

Such a machine is particularly remarkable in that the rotor is supplied according to a system of polyphase currents by means of a mechanical switch supplied with direct current. The rotor obtains its voltage and its current from a voltage source, for example the accumulator battery, therefore in DC and not in AC.

Such a polyphase electric machine is economical because it avoids a costly electronic assembly for the alternating current supply of the multiple phases of the machine from a direct current.

The brushes are also supplied with direct current, they are connected to the same voltage source. They are not connected to the phases of the rotor, it is the groups of blades which are connected to the q phases of the rotor.

According to one aspect of the invention, the machine may have a number of pairs of apparent poles comprised between 1 and 12. In particular, the machine may have 6 pairs of apparent magnetic poles.

According to one aspect of the invention, the winding can be distributed or with fractional pitch.

According to one aspect of the invention, each phase may have a single conductor forming the different winding sections. Each phase can have several conductors assembled together outside the slots. These conductors can be pins, for example U-shaped, for example I-shaped. These pins can be inserted axially and then connected together. Pins provide better performance, especially in terms of engine torque.

According to one aspect of the invention, Nr can be between 2 and 50, preferably between 16 and 24 and for example equal to 20. The number of notches can be equal to Nr, each notch then being placed between two teeth successive rotors.

According to one aspect of the invention, the rotor teeth may have a domed shape.

According to a first variant, the stator comprises Ns stator teeth. The machine has 2*p apparent magnetic poles with 2*p=Nr-Ns and a magnetic reduction ratio G=Ns/2p.

According to this variant, the stator is not powered by a voltage and/or current source. The stator is not wired to a voltage or current source. The stator is pure reluctance. The stator does not include permanent magnets. This electric machine saves expensive raw materials and the manufacturing process is extremely simplified.

According to one aspect of the invention, the stator can be formed by a stack of laminations. The stator may include recesses between each successive stator teeth. These recesses may have a rounded shape.

According to one aspect of the invention, Ns can be between 2 and 50, preferably between 10 and 30 and for example equal to 24.

According to one aspect of the invention, G can be between 1 and 20, preferably between 3 and 15, for example 5, for example 11.

According to a second variant, the stator comprises Na pairs of magnetic poles. The electrical machine has 2*p apparent magnetic poles with p = Nr-Na and G = Na/p. According to this variant, the number of magnetic poles at the stator is not the number of apparent magnetic poles of the electric machine.

According to one aspect of the invention, Na can be between 1 and 50, preferably between 5 and 30 and for example equal to 22.

According to one aspect of the invention, the stator may comprise a yoke equipped with one or more magnets distributed circumferentially. The magnets can be permanent magnets, in particular ferrite, in particular with rare earths. In this case, stator excitation is not necessary. The stator may include one or more Halbach magnetization magnets. Alternatively, the magnets can be electromagnets.

These structures of electric machines, called Vernier, in particular with a large number of teeth, provide a very high torque density, simultaneously with a speed multiplication effect, starting from the mechanical speed of the rotor, going towards the speed of a permeance wave. .

These structures make it possible to obtain a magneto-mechanical reduction effect where the permeance wave, useful for the electromechanical conversion of energy, rotates G times faster than the rotor. The magnetic reduction ratio G is expressed simply as a function of the number of teeth and poles in the stator.

The mechanical switch will paradoxically provide autopilot between the mechanical speed and the power supply, i.e. at a speed identical to that of the permeance wave, i.e. G x the mechanical speed of the rotor and the blades .

According to another aspect of the invention, the phases of the winding can be connected to the blades of the commutator, in particular to the rings of the commutator, via the connection arms.

According to another aspect of the invention, the electric machine can also comprise a fixed rotating brush-holder assembly in which the commutator brushes are housed. The brush holder can surround the commutator.

The electric machine may comprise a casing that is fixed in rotation. The housing can surround the entire stator, rotor and commutator. The housing can be in two parts, a front and a rear. The brush holder can be fixed on the rear part of the casing. The stator can be fixed on the front part of the casing.

According to another aspect of the invention, the collector can be fixed in rotation on the rotor shaft, in particular the sleeve of the collector can be press-fitted. Alternatively, the commutator can be mounted on the rotor shaft in a reversible manner. Running gear may be disposed between the rotor shaft and the housing to support the rotor.

According to a first winding mode, each of the q groups of blades is electrically connected to one of the two ends of one of the q phases of the rotor, the other ends of the q phases are electrically connected together so as to form a star winding.

In a particular example of this first winding mode, q is equal to three, the commutator therefore supplies the rotor according to a three-phase current system. One end of each of the three winding phases can be fixed, in particular by welding to one end of one of the three connecting arms.

According to another aspect of the invention, only one of the two ends of each phase can be connected to a connecting arm. Each group of blades can supply a single and unique phase of the q, in particular three, phases of the rotor. Each group of blades, in particular each collector ring, supplies a separate phase.

According to one aspect of the invention, the collector can also comprise a connector capable of electrically connecting together the ends of the phases of the winding. The connector can be arranged circumferentially next to the free ends of the link arms. The connector can emerge radially from the skeleton. The connector comprises q ends, in particular three, for each receiving each of the phase ends.

According to a second winding mode, each of the q groups of blades is electrically connected to two ends of two distinct phases of the q phases of the rotor so as to form a polygon winding.

In a particular example of this second winding mode, q=3, the commutator therefore supplies the rotor according to a three-phase current system. The winding is therefore in a triangle. One end of each of three winding phases can be fixed, in particular by welding to one end of one of the three connecting arms.

According to another aspect of the invention, each phase of the rotor can be connected to two distinct groups of blades. Each phase of the winding can be connected to two connection arms. Each connection arm can be connected to two phases of the winding. The potential can be identical at both ends of each phase of the winding.

According to a preferred configuration of the electric machine, the stator comprises The stator may comprise one or more magnets with Halbach magnetization and the winding is of fractional pitch.

• une machine électrique tel que décrite précédemment, et
• un hacheur connecté électriquement aux balais du commutateur mécanique et apte à être connecté à la batterie du véhicule.

The invention also relates to a traction system for a transport vehicle comprising:

• an electric machine as described previously, and
• a chopper electrically connected to the brushes of the mechanical switch and adapted to be connected to the battery of the vehicle.

The transport device can be a vehicle, in particular a car. The transport vehicle may be an autonomous vehicle for delivering objects, in particular with wheels, in particular with propellers, for example a vehicle of the “drone” or “droid” type.

The chopper allows the adjustment of the voltage and thus the function of power variator. The chopper here is not an inverter which allows the generation of sinusoidal current signals. A rheostat can be provided instead of the chopper which makes it possible to completely extract the power electronics for supplying the electrical machine.

Such a traction system makes it possible to propel a motor vehicle at low cost.

As a variant, the invention may also relate to an alternator comprising the electrical machine. The invention may also relate to a system comprising the electrical machine that can operate in motor mode and in alternator mode.

Other characteristics and advantages of the invention will become apparent through the description which follows on the one hand, and several embodiments given by way of indication and not limiting with reference to the appended diagrammatic drawings on the other hand, on which :

and

are schematic views, in section, of an electrical machine according to the invention,

and

schematically illustrate the power supply of the winding of the machine according to a first star winding mode,

and

illustrate an example of commutator collector according to the invention for supplying the winding in the first mode.

and

schematically illustrate the power supply of the winding of the machine according to a second triangle winding mode.

,

, and

illustrate an example of commutator collector according to the invention for supplying the winding in the first mode.

illustrates an isolated ring from the collector in Figure 9.

schematically and partially illustrates an electric machine according to the first variant

schematically and partially illustrates an electric machine according to the second variant

There is shown schematically in Figure 1, in section, an electric machine 1. The machine 1 is suitable for equipping a traction system for transport equipment, in particular a motor vehicle.

In the example considered, the machine comprises a rotor 3 mobile in rotation around the axis X of rotation of the machine and a stator 4 fixed in rotation comprising 2*p visible magnetic poles and having a magnetic reduction ratio G. The rotor forms the armature and the stator forms the inductor of the machine. The machine has a number of visible poles p which can be between 1 and 12. In particular, the machine can have 6 pairs of visible magnetic poles.

The machine 1 also comprises a casing 5 fixed in rotation, here in two parts, a front 5a and a rear 5b. The casing surrounds the assembly of the stator and the rotor The casing can be in two parts, The stator 4 is fixed to the front part of the casing, for example mounted by force.

In the example considered, the rotor 3 comprises a rotor shaft 10 and a rotor body 11.

In the example considered, a front bearing 13 and a rear bearing 14 are traversed by the rotor shaft 10. The rotor shaft 10 is mounted for rotation relative to the casing 5, for example by means of rolling members mounted on bearings 13, 14.

For example, the rotor 3 comprises a first drive member 20 belonging to the machine 1. A second drive member 21 mounted on an element of a traction chain, for example a crankshaft, of the motor vehicle, and a element 22 transmitting the rotational movement of the second drive member 21 to the first drive member 20 are provided. According to a particular example, the drive members 20, 21 are pulleys and the element 22 transmitting the movement is a belt.

As best seen in Figure 2, the pulley 20 is mounted integral in rotation on the rotor shaft 10. The rotor shaft can therefore be driven in rotation by the rotational movement of the pulley 20. The pulley 20 is arranged on a first end of the shaft 14, called the front end. The shaft 14 has a second end, called the rear end, opposite the front end.

In the example considered in figure 1, the machine is in a second variant. The stator 4 comprises a yoke equipped with one or more magnets distributed circumferentially. The magnets here are electromagnets. For example, the stator comprises Na pairs of magnetic poles, with Na = 22.

In the example considered, the electromagnets are supplied with a DC excitation electric current EXC coming from a stator chopper 25. The stator 4 is supplied through the stator chopper by a voltage source which is here the vehicle battery B. The excitation winding is connected to the B+ terminal of battery B.

As a variant of the electromagnets, the stator can have one or a plurality of permanent magnets to form the Na poles. These magnets can be ferrite or rare earth. Preferably, the magnets are Halbach magnetized. In the case of permanent magnets, stator excitation is not necessary. The stator is not wired to a voltage or current source. A machine according to this second variant is illustrated in figure 14.

In a first variant of the machine 1, the stator 4 this time comprises Ns stator teeth. Ns can be equal to 24. The stator 4 can be formed by a stack of laminations. A machine according to this first variant is illustrated in figure 13.

According to this first variant, the stator is not powered by the battery. The stator is not wired to a voltage or current source. The stator 4 is pure reluctance. The stator does not include permanent magnets.

In the example considered, the rotor body 11 comprises a stack of laminations, made of ferromagnetic material, comprising laminations stacked axially. The lamination package comprising Nr rotor teeth and a plurality of axial expansion slots.

In the example considered, Nr can be between 2 and 50, for example equal to 20. The number of notches can be equal to Nr, each notch then being arranged between two successive rotor teeth.

In its first variant, machine 1 has 2*p visible magnetic poles with 2*p = Nr-Ns and a magnetic reduction ratio G = Ns/2p.

In its second variant, machine 1 has 2*p apparent magnetic poles with p=Nr-Na and G=Na/p.

The rotor body 11 also comprises at least one winding 30, the winding being divided into q phases. The phases include winding sections 31 housed in the slots, the sections of each phase succeeding each other circumferentially. Each phase has two ends 32. The notches are separated from each other by rotor body teeth. The winding can be distributed or fractionally pitched.

In the example considered in figure 2, q = 3, the winding is therefore a three-phase winding whose phases are a, b and c. The rotor 3 is therefore supplied according to a three-phase current system.

The phases of the winding 30 can be connected in a star or in a polygon. In this embodiment, the rotor has three phases a, b, c connected in a triangle, as shown in Figure 2.

In the example considered, each sheet may have an annular shape and include grooves arranged radially. The notches of the stacked sheets form the notches of the stack of sheets extending in a direction substantially parallel to the axis X. Between the notches are formed the Nr rotor teeth.

In the example considered, each phase a, b, c can have a single conductor forming the different winding sections.

In the example considered, buns 35 formed by the winding 30 are arranged on either side of the stack of sheets.

The machine 1 according to the example considered is particularly remarkable in that it comprises a mechanical switch 40 to supply the q phases of rotor 3. In the example considered, in FIGS. 1 and 2, the mechanical switch therefore supplies the rotor 3 with a three-phase current system. The switch 40 is arranged inside the casing.

In the example considered, the switch 40 comprises a commutator 41 mobile in rotation around the axis X. The commutator will be described in more detail in the following references. The commutator 41 is fixed in rotation on the rotor shaft 10 and forms with the rotor 3 the armature of the machine 1.

In the example considered, the switch 40 also comprises at least one pair of brushes with radial extension, a positive brush 45 and a negative brush 46, able to rub on the commutator 41. The brushes 45, 46 are fixed in rotation, they are each defined on an angular sector and they are connected to the same voltage source, here battery B of the vehicle. The brushes are therefore supplied with direct current.

In the example considered, a chopper 48 is arranged between the brushes 45, 46 and the B+ terminal of the battery B to regulate the voltage and act as a voltage variator.

In the example considered, the brushes 45, 46 have a substantially parallelepipedal shape. Each brush has a cylindrical radially inner surface in contact with the commutator 41.

In the example considered, the machine 1 comprises a brush holder assembly 50 fixed in rotation in which the brushes 45, 46 are housed. The brush holder 50 carries the brushes. The brush holder 50 surrounds the collector 41. The brush holder is fixed to the casing, in particular on the rear part 5b of the casing. The brush holder can be fixed on the rear bearing 14 or directly on the yoke of the stator.

When machine 1 operates in generator mode, pulley 20 and rotor 3 are driven in rotation and the winding of rotor 30 is electrically powered by switch 40. Rotor 3 is then magnetized, a magnetic field is created and generates a current armature in the stator winding.

The operation and structure of the switch will now be described in detail.

FIGS. 3 and 4 schematically illustrate the supply by a three-phase current system of the winding of a rotor 3 of a machine 1 comprising two pairs of visible poles, i.e. p=2, according to a first star winding mode and according to the first machine variant, i.e. pure reluctance. Figures 3 and 4 show the commutator 40 and the winding of the rotor 30 unwound.

With reference to FIG. 3, the collector 41 comprises G*p*q conductive blades 60 succeeding each other circumferentially, with here G=2, p=2 and q=3, therefore 12 conductive blades. Only half of the 12 blades 60 are represented here. Each blade 60 is defined on an angular sector, the adjacent blades are isolated from each other. The conductive blades are divided into q groups, here three groups a', b', c'. All the blades 60 of the same group a', b', c' are electrically connected together and the three groups are alternated circumferentially.

In the example considered, the collector 41 has an elementary blade pattern which is repeated G*p times, here four times. The basic pattern of blades is here: blade of group a', blade of group b' and blade of group c'. Collector 41 presents G*p*q passages, here twelve, from one type of blade to another. The type of a blade is defined by membership in a group. The collector thus has an elementary pattern equal to 2*π/(G*p*q), ie π/6 or even 30°.

In the example considered, each of the three groups a', b', c' of blades is electrically connected to one of the two ends 32 of one of the three phases a, b, c of the rotor 3. The other ends 32 of the three phases are electrically connected together so as to form a star winding.

In the example considered in Figures 3 and 4, G=2 and p=2 gives us Nr = 12 and Ns = 8.

In the example considered, the rotor can comprise 12 slots, as many as Nr rotor teeth. Each of the twelve commutator blades is aligned with a rotor body tooth. Each of the notches in which is housed a section belonging to a phase of the type q is aligned axially with a blade of the collector 41 of the same type.

In the example considered, all the blades all have the same angular sector and the same axial dimension. In particular, all the blades 60 are identical and are not axially offset. The blades 60 can be made of copper. The blades 60 can have a radial thickness comprised between 1mm and 3mm, for example 2mm. The blades can have an axial dimension between 8mm and 12mm, for example 10mm.

Referring to Figure 4, the switch comprises a single pair of brushes 45, 46 always in contact with the blades 60. Two pairs of brushes could have been considered because the number of pairs can be between 1 and p. The brushes of the pair shown are circumferentially offset from each other by [(2k+1)*2*π]/(2*G*p)], k being a natural number. In the example considered, the brushes can therefore be offset, for example, by an angle of π/2 or 3π/2, here the brushes 45, 46 are offset by π/2.

The angular offset between the brushes 45, 46 is from center to center, that is to say between the median planes A of each brush.

In the example considered, each blade 60 is separated from the two adjacent blades 60 by an insulating inter-blade 62. The angular opening of each inter-blade 62 is identical.

In the example considered, the angular opening of each brush 45, 46 is greater than the angular opening of the inter-blades 62. Thus, each brush is always in contact with at least one blade and with two blades during the phases of recovery.

With reference to FIGS. 5 and 6, we will now describe a concrete variant of collector 41 for the supply by a three-phase current system (q=3) of a machine 1 with two pairs of apparent poles and with a reduction ratio magnetic G equal to 4 with a star winding. The collector therefore has an elementary pattern equal to 2*π/(G*p*q), ie π/12 or even 15°.

In the example considered, each inter-blade 62 comprises an insulated blade 63 which is not electrically connected to any other blade. Blades 63 are said to be insulated in contrast to electrically connected conductive blades 60 which form the three groups of blades. The insulated blades are at floating potential. The insulated blades 63 are separated from the conductive blades 60 by interstices 64 which can measure between 1mm and 5mm in the circumferential direction.

According to one aspect of the invention, the angular opening of the insulated blades 63 is between 40% and 50% of the angular opening of the conductive blades 60.

In the example considered, the collector comprises 48 blades, 24 conductive blades 60 (G=4, p=2 and q=3) and 24 insulated blades 63, the conductive blades 60 being alternated with the insulated blades 63.

In the example considered, the collector 41 has G*p*q passages, here 24 passages, from one type of conductive blade to another. The type of a blade is defined by membership in a group. Isolated blades do not belong to any group.

In the example considered, the collector 41 comprises a skeleton 65, made of insulating material, for example plastic, of revolution around the axis X to hold the blades 60, 63 in position. The skeleton is substantially cylindrical in shape. Skeleton 60 is here in one piece. The skeleton comprises 48 radial openings 67 receiving the blades 60, 63. The skeleton comprises a central opening 68 receiving the rotor shaft 10. The collector 41 also comprises a central hub 69 for the passage of the rotor shaft. The skeleton is fixed to the central hub, for example molded onto the central hub 69.

Figure 6 is an exploded view of the collector of Figure 5. The blades 60 of the same group a', b', c' are all electrically connected to a ring disposed radially inside the blades. In the example considered, the commutator comprises a ring of type a 70 to connect together the blades 60 of group a', a ring of type b 71 and a ring of type c 72.

In the example considered, the rings 70, 71, 72 follow one another axially. The type b ring is central and the type a and type c rings are at the ends. The rings are axially distributed over an axial length of blade 60.

In the example considered, a bridge 75 is provided between each blade 60 and the associated ring 70, 71, 72. Each bridge is associated with a single blade 60. The bridges 75 extend radially from the rings without axial offset.

The bridges 75 of the b-type ring 71, central, are connected to a central zone of the blades 60. The bridges 75 of the end rings 70, 72 are connected to the corners of the blades 60.

The bridges and the rings are in an interior space of the skeleton 67 while the blades 60 are flush towards the exterior to come into electrical contact with the brushes 45, 46.

In the example considered, the blades 60 of the same group a', b', c', the bridges 75 and the ring 70, 71, 72 form a ring in one piece. The collector thus comprises an a-type ring 77, a b-type ring 78 and a c-type ring 79. The b-type ring 78 is shown separately in Figure 8.

In the example considered, the isolated blades are fixed on an inter-blade ring 73. The inter-blade ring 73 is arranged in the interior space of the skeleton 65. The inter-blade ring 73 radially to the outside of the rings 70, 71, 72. The insulated slats 63 have a foot 74 inserted into an opening of the inter-blade ring by fixing the insulated slat.

The inter-blade ring 73 includes windows 76 for the passage of the bridges 75 between the blades 60 of group b and the ring 72 which is in the central position. Thus, the bridges 75 of the b-type ring 78 cross the inter-blade ring 73.

In the example considered, the manifold 41 comprises three link arms 80, each being integral with one of the rings 70, 71, 72. Each link arm comprises a portion which is integral with the rings and a portion comprising the end free 81. The two portions are fixed to one another, for example by welding. Each free end 81 is connected to a winding phase a, b, c to supply it. Each connecting arm 80 emerges radially from the skeleton 65 of the manifold through a radial hole 82 formed in the skeleton.

In the example considered, only one of the two ends 32 of each phase a, b, c is connected to a connecting arm. Each group of blades a’, b’, c’ thus supplies a single and unique phase of the 3 phases of the rotor.

In the example considered, the collector 41 also includes a connector 90 for electrically connecting together the ends 32 of the phases a, b, c. The connector 90 is arranged circumferentially next to the free ends 81 of the connecting arms. The connector 90 emerges radially from the skeleton 67. The connector comprises three ends 91, for each receiving each of the phase ends 32. Thus each phase a, b, c comprises an end 32 connected to a connecting arm 80 and an end connected to the connector 90.

FIGS. 7 and 8 schematically illustrate the supply by a three-phase current system of the winding of a rotor 3 of a machine 1 comprising two pairs of visible poles (p=2) and a magnetic reduction ratio G equal to two according to a second winding mode (triangle). Figures 12 and 13 partially show the commutator 40 and the winding of the rotor 30 unwound.

This example differs from that illustrated in FIGS. 3 and 4 in that each of the 3 groups of blades a', b', c' is electrically connected to two ends 32 of two distinct phases a, b, c so as to form a winding in a triangle.

In the example considered, each phase a, b, c is connected to two separate blade groups a', b', c'.

With reference to FIGS. 9 to 12, a description will now be given of a switch 40 for the supply by a three-phase current system (q=3) of a machine 1 with two pairs of poles and with a reduction ratio G equal to 3 with a triangle winding.

In the example considered, the collector here comprises 18 conductive blades 60. (G=3, p=2 and q=3). collector 41 presents G*p*q passages, here 18, from one type of blade to another. The collector 40 has an elementary pattern of blades which is repeated G*p times, here 6. The elementary pattern is here: blade of group a', blade of group b' and blade of group c' (a', b', vs').

The collector 40 considered here differs from that of the previous ones in that it does not include a connector. The collector comprises only 3 connecting arms 80 which each receive two phase ends 32. The ends 32 are for example fixed by welding. Each phase a, b, c is therefore connected to two connecting arms 80 and each connecting arm 80 is connected to two phases of the winding. The potential is identical at the two ends 32 of each phase a, b, c.

FIG. 13 schematically presents a machine 1 according to the first variant in which Nr=24, Ns=20. The number of visible poles p is thus equal to 2, the magnetic reduction ratio G equal to 5 and the number of blades of the collector equal to 30. The number of notches is equal to 24.

In the example considered, according to one aspect of the invention, the Ns rotor teeth have a domed shape. The stator comprises recesses between each successive stator teeth each having a rounded shape.

Finally, FIG. 14 schematically presents a machine 1 according to the first variant in which Nr=24, Na=22. The number of visible poles p is thus equal to 2, the magnetic reduction ratio G equal to 11 and the number of blades of the collector equal to 66. The number of notches is equal to 24.

Claims (10)

Mechanical switch (40) for an electrical machine (1) suitable for supplying by a polyphase current system comprising q phases, with q positive integer strictly greater than 1, a rotor (3) of a rotating electrical machine having 2*p visible magnetic poles and a magnetic reduction ratio G, comprising:

• a commutator (41) mobile in rotation around an axis (X) of the electrical machine, with an elementary pattern equal to 2*π/(G*p*q),
• at least one pair of brushes with radial extension, a positive brush (45) and a negative brush (46), capable of rubbing on the commutator (41), fixed in rotation, each defined on an angular sector, capable of being connected to one and the same vehicle battery (B),

characterized in that the mechanical commutator (41) comprises G*p*q, with integer G, conductive strips (60) succeeding each other circumferentially, each strip (60) being defined on an angular sector, the adjacent strips being insulated from each other others, the slats being divided into q groups (a', b', c'), all the slats (60) of the same group being electrically connected together, the q groups being alternated circumferentially,
and in that the brushes (45, 46) of the same pair are circumferentially offset from each other by [(2k+1)*2*π]/(2*G*p), k being a whole natural. Mechanical switch (40) according to claim 1, the blades (60) of the same group (a', b', c') all being electrically connected to a ring (70, 71, 72) disposed radially inside blades (60). Mechanical switch (40) according to the preceding claim, the sum of the angular opening of a brush (45, 46) and the angular opening of a blade (62) being greater than or equal to 120 electrical degrees and strictly less than 180 degrees electric Electric machine (1) comprising:

• a mechanical switch (40) according to any one of claims 1 to 3,
• a stator (4) fixed in rotation, the stator (4) forming the inductor of the machine,
• a rotor (3) rotatable about the axis (X) of the electric machine, the rotor (3) forming with the commutator (41) an armature of the machine, the rotor comprising:
  1. a rotor shaft (10), and
  2. a rotor body (11) comprising:
     1. a lamination package comprising axially stacked laminations, the lamination package including Nr rotor teeth, the lamination package (10) having a plurality of axially extending slots,
     2. at least one winding (30), the winding being divided into q phases (a, b, c) powered by the switch (40), the phases comprising winding sections housed in the notches, the sections (31) of each phase circumferentially succeeding each other, each phase having two ends (32).

Electrical machine (1) according to the preceding claim, comprising in which the stator (4) comprises Ns stator teeth, the machine having 2*p visible magnetic poles with 2*p=Nr-Ns and G=Ns/2p. Electric machine (1) according to Claim 4, in which the stator (4) comprises Na pairs of magnetic poles, the electric machine having 2*p visible magnetic poles with p = Nr-Na and G = Na/p. Electric machine (1) according to the preceding claim, in which the stator (4) comprises one or more magnets with Halbach magnetization and the winding (30) has fractional pitch. Electric machine (1) according to any one of Claims 4 to 7, each of the q groups of blades (a', b', c') being electrically connected to one of the two ends (32) of one of the q phases ( a, b, c) of the rotor, the other ends (32) of the q phases being electrically connected together so as to form a star winding (30). Electric machine (1) according to any one of Claims 4 to 7, each of the q groups of blades (60) being electrically connected to two ends (32) of two distinct phases of the q phases (a, b, c) of the rotor so as to form a winding (30) in polygon. Traction system for a transport vehicle comprising:

• an electric machine (1) according to one of Claims 4 to 8, and
• a chopper (48) electrically connected to the brushes (45, 46) of the mechanical switch (40) and adapted to be connected to the battery (B) of the vehicle.