FR3098040A1 - WATER-COOLED ROTATING ELECTRIC MACHINE - Google Patents

Abstract

The invention relates mainly to a rotary electrical machine (10), in particular for a motor vehicle, comprising: - a stator (11) comprising a stator body (30) and a winding (33) inserted in notches of the stator body ( 30), - a rotor (12) comprising a rotor body (21) and poles formed by permanent magnets (22), characterized in that the permanent magnets (22) are rare earth magnets, the winding (33 ) being formed by conductive elements in the form of pins and in that said rotary electrical machine (10) comprises a water cooling circuit (17). Figure for abstract: Figure 4

Description

ELECTRIC ROTATING MACHINE WITH WATER COOLING

The present invention relates to a water-cooled rotating electric machine. The invention finds a particularly advantageous, but not exclusive, application with high-power reversible electric machines that can operate in alternator mode and in motor mode.

In a manner known per se, rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be integral with a driving and/or driven shaft and may belong to a rotating electric machine in the form of an alternator, an electric motor, or a reversible machine that can operate in both modes.

The stator is mounted in a housing configured to rotate the shaft, for example via bearings. The rotor comprises a body formed by a stack of sheet metal sheets held in the form of a package by means of a suitable fastening system, such as rivets passing axially through the body of the rotor right through. The rotor comprises poles formed for example by permanent magnets housed in cavities formed in the magnetic mass of the rotor, as described for example in document EP0803962. Alternatively, in a so-called "salient" pole architecture, the poles are formed by coils wound around the arms of the rotor. The machine can be asynchronous and synchro-reluctant.

Furthermore, 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 phase windings. These phase windings pass through the notches of the body of the stator and form buns protruding from either side of the body of the stator. The phase windings are obtained for example from a continuous wire covered with enamel. These windings are polyphase windings connected in star or in triangle whose outputs are connected to a voltage and current rectifier power bridge.

In certain types of motor vehicle traction chains, a high-power reversible rotating electrical machine is coupled to the vehicle gearbox or to a train of the motor vehicle. The electric machine is then able to operate in an alternator mode in particular to supply energy to the battery and/or to the on-board network of the vehicle, and in a motor mode, not only to ensure the starting of the combustion engine, but also to participate in the traction of the vehicle alone or in combination with the internal combustion engine.

The applicant has developed a range of 48V synchronous electrical machines comprising a rotor with permanent magnets made of ferrite. These water- or oil-cooled machines can deliver a power of 15kW. The present invention aims to optimize the configuration of the electric machine in order to obtain a compact model that is therefore easily implantable in the environment of the vehicle while being able to deliver increased power compared to existing configurations.

To this end, the invention proposes a rotating electrical machine, in particular for a motor vehicle, comprising:
- a stator comprising a stator body and a winding inserted in notches of the stator body,
- a rotor comprising a rotor body and poles formed by permanent magnets,
characterized in that the permanent magnets are rare-earth magnets, the winding being formed by conductive elements in the form of pins and in that the said rotating electric machine comprises a water cooling circuit.

According to one embodiment, the rotating electrical machine has a nominal power of 25 kW.

According to one embodiment, a pole is formed by permanent magnets implanted in a V shape.

According to one embodiment, the permanent magnets are located on the outer periphery of the rotor.

According to one embodiment, the stator contains four conductors per slot.

According to one embodiment, a number of pole pairs is between 4 and 8 and is preferably 5.

According to one embodiment, a power inverter is arranged against a rear end face of the rotating electrical machine.

According to one embodiment, a power inverter is arranged on one side, in particular radial, of the rotating electrical machine.

According to one embodiment, the water cooling circuit comprises a cooling chamber for the circulation of water delimited by an outer periphery of a front bearing and an inner periphery of a rear bearing.

According to one embodiment, the cooling chamber is closed at its axial ends by two O-ring seals.

According to one embodiment, the cooling chamber is in communication with a cooling chamber of a heat sink of an inverter.

According to one embodiment, the poles have a rounded shape so as to obtain a continuous magnetic flux in an air gap extending between the rotor and the stator.

According to one embodiment, the rotor and/or the stator has a twisted configuration in which the laminations of the rotor body and/or the laminations of the stator body are angularly offset relative to each other along their circumference.

According to one embodiment, said rotating electrical machine has a transient mechanical power in motor mode for 30 seconds under a minimum of 36 volts which is 16 kW.

According to one embodiment, said rotating electrical machine has a transient mechanical power in motor mode for 30 seconds under a minimum of 48 volts which is 21 kW.

According to one embodiment, said rotating electrical machine has a transient mechanical power in motor mode for 30 seconds under a minimum of 52 volts which is 26 kW.

The invention will be better understood on reading the following description and on examining the accompanying figures. These figures are given only by way of illustration but in no way limit the invention.

Figure 1 is a perspective view of a rotating electrical machine according to the present invention;

Figure 2 is an exploded perspective view of a rotating electrical machine according to the present invention;

Figure 3 is a perspective view of a rotating electrical machine coupled with a motor vehicle train differential;

Figure 4 is a longitudinal sectional view of a rotary electrical machine according to the present invention;

Figure 5 is a perspective view of an inverter of the rotating electrical machine according to the invention;

Figure 6 is an exploded perspective view of a stator of the rotating electrical machine according to the invention;

FIG. 7 is an exploded perspective view of a rotor of the rotating electrical machine according to the invention.

Identical, similar or analogous elements retain the same reference from one figure to another.

In the following description, the front of the machine is located on the output side of the shaft meshing with an element external to the electric machine, while the rear of the electric machine is located on the opposite side.

Figures 1 and 2 show a rotating electric machine 10 comprising a polyphase stator 11 surrounding a rotor 12 of axis X corresponding to the axis of the electric machine 10. The rotor 12 is mounted on a shaft 13. The stator 11 is carried by a front bearing 15 and a rear bearing 16 configured to carry the shaft 13 in rotation via ball bearings 14. The stator 11 of the machine surrounds the rotor 12 with the presence of an air gap between the internal periphery of the stator 11 and the outer periphery of the rotor 12. The electric machine 10 comprises a cooling circuit 17 by water.

More specifically, as can be seen in Figure 4, the water cooling circuit 17 comprises a cooling chamber 17.1 delimited by the outer periphery of the front bearing 15 and the inner periphery of the rear bearing 16. This cooling chamber 17.1 is closed at its axial ends by two seals 24 of the O-ring type. This cooling chamber 17.1 is in communication with a cooling chamber 17.2 of a heat sink of an inverter 38, as shown in figure 1.

The stator 11 is preferably shrunk-mounted inside the front bearing 15 so as to establish intimate contact between the outer periphery of the stator body 30 and the inner periphery of the front bearing 15. The bearings 15 and 16 may be made of aluminum or steel. The front bearing 15 may also include fixing lugs 19 provided with holes for the passage of fixing members such as screws to allow the fixing of the front bearing 15 on the rear bearing 16.

The assembly of the electric machine 10 is carried out from the back to the front. It is thus possible to implement a simplified, standard, and automated assembly method.

The front bearing 15 is equipped with a front bearing 14 mounted just or slightly tight in the bearing 15. An outer ring of the bearing 14 is held by a plate screwed onto the bearing 15. As can be seen in Figure 2, a speed sensor 18, in particular a Hall effect sensor, used in combination with a target connected in rotation with the rotor makes it possible to measure the field variations to deduce the speed of rotation of the rotor 12.

The rotor 12 is press-fitted onto the front bearing 14. The shaft 13 is fitted with straight, helical or smooth splines 20 with clamping to achieve coupling with a gearbox or a differential 27 of a train 29 of motor vehicle, as shown in Figure 3. In such an architecture, the shaft 13 of the electric machine 10 is parallel to the train 29 of the motor vehicle. As a variant, the shaft 13 of the electric machine 10 could be arranged orthogonally with respect to the train 29.

More specifically, as can be seen in Figure 7, the rotor 12 comprises a rotor body 21 in the form of a package of laminations to reduce eddy currents, as well as poles constituted by permanent magnets 22 in earths rare arranged inside cavities 23 of corresponding shape.

A pole is formed by rare-earth magnets 22 implanted in a V-shape on the outer periphery of the rotor 12. The number of pairs of poles is between 4 and 8, and is preferably 5.

The rotor 12 is held by tie rods 25 in the same number as the number of poles of the rotor 12. These tie rods 25 pass through two balancing parts 26 as well as all the magnetic laminations of the rotor body 21.

Holding members 28, such as springs or tabs or any other equivalent means, are arranged so as to hold the permanent magnets 22 in position inside the cavities 23.

The shape of the poles of the rotor 12 is defined so as to obtain a continuous magnetic flux in the air gap. The poles advantageously have a rounded shape with a minimum radius of 5 degrees. This reduces magnetic forces in the air gap as well as noise.

The configuration of the poles makes it possible to have a reluctance effect (Ld different from Lq) typically comprised between 5 and 10%, which makes it possible to increase the nominal torque of the electric machine 10 by at least 3%.

It will be possible to twist the rotor 12, that is to say that the plates of the rotor body 21 can be angularly offset relative to each other along their circumference. The sheets can for example be staggered by forming four packs of sheets, the sheets of the same pack being aligned. In order to achieve this shift, which makes it possible to gradually shift the poles, split permanent magnets 22 may be used. of signal waves in the air gap (phase currents and voltages). Each magnet of the same pole can be associated with a stack of laminations. Each pole extends, for example, circumferentially over 7 degrees.

Furthermore, as shown in Figure 6, the stator 11 comprises a body 30 in the form of a stack of laminations provided with notches 31, for example of the semi-closed type, equipped with notch insulation 32 for mounting of a winding 33. The winding 33 comprises a set of phase windings 34 made from conductive elements 35 in the form of pins connected together for example by welding. The stator 11 advantageously contains four conductors per slot 31, one conductor corresponding to a branch of a winding pin 33. These windings are, for example, three-phase windings connected in a star or in a triangle. The stator 11 may also have a twisted configuration in which the laminations of the stator body 30 are angularly offset relative to each other along their circumference.

The phase outputs 37 visible in FIG. 2 are connected to a power inverter 38 comprising electronic components, such as diodes or transistors, for example of the MOSFET type. As can be seen in Figure 5, the inverter 38 may include a water cooling circuit 40 having an inlet 41 and a water outlet 42, so that water can pass through the inverter 38. The output 42 is intended to cooperate with the connector 42.1 of the chamber 17.2 (see Figures 1 and 2). This cooling circuit 40 is thus compatible with an electric machine 10 also cooled by water in order to reduce production costs .

An interconnector 43 visible in FIG. 2 makes it possible to group the phase outputs 37 of the electric machine 10 according to a predefined angular sector. Interconnector 43 is compatible for delta or star phase connections. In the case of a double three-phase star type system, there are two independent neutral points. It is possible to make an interconnector 43 for multiphase machines. The machine output shaft 13 is provided on the same side as the phase output interconnector 43.

As illustrated by Figures 2 and 3, the inverter 38 may also be arranged on a radial side of the electric machine 10. The inverter is then radially above the electric machine. A bend is then made between the axial phase outputs 37 and the connection terminals of the inverter 38.

As a variant, the inverter 38 could be arranged against a rear end face of the electric machine 10, as shown in FIG. 4. The connections between the phase outputs and the inverter 38 could be axial.

The desired performances of the electric machine 10 are indicated below. The electric machine 10 has a torque of the order of 82 Nm at low speed.

The electric machine 10 has a transient mechanical power in motor mode for 30 seconds under a minimum of 36 volts which is 16 kW. The continuous power is 14 kW in continuous mode, that is to say for operation in motor mode for a period of more than 1 minute.

The electric machine 10 has a mechanical transient power in motor mode for 30 seconds under a minimum of 48 volts which is 21 kW. The continuous power is 18 kW in continuous mode, that is to say for operation in motor mode for a period of more than 1 minute.

The electric machine 10 has a transient mechanical power in motor mode for 30 seconds under a minimum of 52 volts which is 26 kW. The maximum speed is at least 20000 rpm in continuous mode.

According to a particular embodiment, the electric machine 10 is of the double three-phase type with an axial length of iron in the rotor 12 and the stator 11 of the order of 66 mm, a diameter of the order of 161 mm and a weight around 15 kg. By “around” is meant a variation of plus or minus 10% around the value.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention, which would not be departed from by replacing the various elements with any other equivalents.

Claims (10)

Rotating electrical machine (10), in particular for a motor vehicle, comprising:
- a stator (11) comprising a stator body (30) and a winding (33) inserted into notches (31) of the stator body (30),
- a rotor (12) comprising a rotor body (21) and poles formed by permanent magnets (22),
characterized in that the permanent magnets (22) are rare earth magnets, the winding (33) being formed by conductive elements (35) in the form of pins and in that the said rotating electric machine (10) comprises a circuit cooling (17) by water. Rotating electrical machine according to Claim 1, characterized in that the rotating electrical machine (10) has a nominal power of 25 kW. Rotating electric machine according to Claim 1 or 2, characterized in that one pole is formed by permanent magnets (22) implanted in a V-shape. Rotating electrical machine according to any one of Claims 1 to 3, characterized in that the stator (11) contains four conductors per slot (31). Rotating electrical machine according to any one of Claims 1 to 4, characterized in that a number of pairs of poles is between 4 and 8 and is preferably 5. Rotating electrical machine according to any one of Claims 1 to 5, characterized in that a power inverter (38) is arranged against a rear end face of the rotating electrical machine (10). Rotating electrical machine according to any one of Claims 1 to 5, characterized in that a power inverter (38) is arranged on one side of the rotating electrical machine (10). Rotary electric machine according to any one of Claims 1 to 7, characterized in that the water cooling circuit (17) comprises a cooling chamber (17.1) for the circulation of water delimited by an outer periphery of a bearing front (15) and an inner periphery of a rear bearing (16). Rotary electric machine according to Claim 8, characterized in that the cooling chamber (17.1) is closed at its axial ends by two seals (24) of the O-ring type. Rotary electric machine according to Claim 8 or 9, characterized in that the cooling chamber (17.1) is in communication with a cooling chamber (17.2) of a heat sink of an inverter (38).