Electrical connection assembly for electric traction motor

Abstract

Electrical connection assembly for electric traction motor The invention relates to a connection assembly for an electric traction motor, the electric traction motor being adapted to be powered by a three-phase electricity source and comprising three phase terminals. This assembly (2) comprises a set of three separate single-pole connection boxes (6A, 6B, 6C), each single-pole connection box comprising a metal outer casing (14A, 14B, 14C) connected to an electrical ground of the electric motor, an inner casing (18A, 18B, 18C) made of insulating material, a connection terminal (8, 10, 12) to a phase of the traction motor and a connection terminal (20A, 20B, 20C) to a phase of an electricity source. Figure for the abstract: figure 1

Description

Title of the invention: Electrical connection assembly for electric traction motor

[0001] The present invention relates to an electrical connection assembly for an electric traction motor adapted to be powered by a three-phase electricity source and comprising three phase terminals, an electric traction motor and an associated electric traction vehicle.

[0002] The invention lies in the field of the electrical supply of electrical machines, in particular electric traction motors, and their protection.

[0003] The invention applies in particular to electrically powered vehicles, for example railway vehicles (train, tram, metro). This type of electrically powered vehicle is supplied with electricity by an external electrical energy source, for example a catenary, using a conventional pantograph system.

[0004] In a known manner, in an electrically driven vehicle, an electric traction motor, of the asynchronous or synchronous type with permanent magnets, is powered by an electrical energy source, for example an inverter or any other power supply means. The inverter is designed to process the electrical energy captured by the vehicle, for example by means of a pantograph system, and supply it to the electric motor. The inverter is connected to a terminal block of the motor by a three-phase contactor, which is a means of isolating the inverter from the motor.

[0005] However, in the case of a permanent magnet synchronous motor, even if the contactor is open, a voltage is maintained at the terminals of the motor when it is driven by the forward motion of the electric vehicle. Thus, in the event of an electric arc occurring, following a failure of the insulation, the arc is maintained as long as the electric motor is rotating. Such a phenomenon can lead to destruction of the motor and total blocking of the motor.

[0006] Patent FR3050885 describes a three-phase terminal block for an electrical machine, which is produced in the form of a single housing comprising three connection compartments separated by partitions, and intermediate conductive cores connected to the ground of the electrical machine. This terminal block has the advantage of diverting a short circuit to the electrical ground of the electrical machine via one of the conductive cores, so that damage to the electrical machine caused by an electrical fault is at least partially avoided. However, in the event of destruction of the separating partitions following the occurrence of an electric arc, the insulation between the terminals is no longer ensured, the electric arc risks propagating between the phase terminals and causing the destruction of the electric motor.

[0007] The object of the invention is to improve safety by reducing the risk of total or partial destruction of the electric motor in the event of an electrical fault occurring.

[0008] To this end, the invention proposes, according to one aspect, a connection assembly for an electric traction motor, the electric traction motor being adapted to be powered by a three-phase electricity source and comprising three phase terminals. This assembly comprises a set of three separate single-pole connection boxes, each single-pole connection box comprising a metal outer casing connected to an electrical ground of the electric motor, an inner casing made of insulating material, a terminal for connection to a phase of the traction motor and a terminal for connection to a phase of an electricity source.

[0009] Advantageously, the connection assembly according to the invention comprises three physically separate single-pole connection boxes, each box comprising a metal outer casing connected to ground, which prevents propagation of an electric arc from one connection terminal to another, and consequently from one phase to another. Advantageously, this prevents destruction of the electric motor in the event of the occurrence of an electrical insulation fault causing an electric arc.

[0010] The connection assembly according to the invention may also have one or more of the characteristics below, taken independently or in any technically conceivable combination:

[0011] - the outer metal casing is made of steel;

[0012] - the outer metal casing is made of aluminum;

[0013] - the insulating material is glass;

[0014] - the inner envelope is made by a mica coating;

[0015] - each single-pole connection box comprises a mechanical connection plate metal, said connection terminal to a phase of the traction motor being connected to said connection plate, the assembly further comprising a fixing member adapted to fix the connection terminal to said connection plate.

[0016] According to another aspect, the invention relates to an electric traction motor adapted to be powered by a three-phase electricity source and comprising three phase terminals, comprising a connection assembly as briefly described above, each phase terminal of the electric traction motor being connected to a connection terminal of a single-pole connection box of said connection assembly.

[0017] According to another aspect, the invention relates to an electrically driven vehicle comprising an electric traction motor comprising a connection assembly of the type described above, the vehicle comprising a three-phase electrical power supply device comprising three electrical power supply terminals, each electrical power supply terminal being connected to a connection terminal of the assembly connection.

[0018] Other characteristics and advantages of the invention will emerge from the description given below, for information purposes only and in no way limiting, with reference to the appended figures, among which:

[0019] [Fig-1] [Fig.l] is a diagram of a connection assembly according to a method of rea lization of the invention.

[0020] In an exemplary embodiment, illustrated in [Fig.l], an electrical connection assembly 2 for an electric traction motor 4, suitable for driving an electrically driven vehicle, for example a railway vehicle (train, metro, tram) in motion, comprises a set of three single-pole connection boxes 6A, 6B, 6C.

[0021] These single-pole connection boxes 6A, 6B, 6C are physically separated.

[0022] For example, the three single-pole connection boxes 6A, 6B, 6C are positioned next to each other as shown in [Fig.l], for example two adjacent boxes, for example 6A and 6B or 6B and 6C, are placed at a distance D from each other, the distance D being for example between 10 and 20mm. In this embodiment, the overall size of the connection assembly 2 is substantially greater than the size of a monolithic three-phase connection terminal block.

[0023] In an alternative embodiment not shown, the single-pole connection boxes 6A, 6B, 6C forming an electrical connection assembly 2 are placed at any distance from each other, according to a design choice.

[0024] The electric motor 4 is in this example a permanent magnet type motor (PMM motor) comprising a 3-phase winding. Each single-pole connection box comprises a phase connection terminal 8, 10, 12, connected to one of the three phases. Such a connection terminal is for example in the form of a metal contact piece.

[0025] The electrically powered vehicle comprises a power circuit, not shown, for supplying each of the phase terminals.

[0026] In one embodiment, the single-pole connection boxes 6A, 6B, 6C are structurally identical, each box being intended to connect one phase among the 3 phases of the electric motor to a three-phase electricity source, which is in one embodiment a three-phase external electrical power supply device, for example an inverter 26.

[0027] Each single-pole connection box 6A, 6B, 6C comprises a metallic outer casing 14A, 14B, 14C connected to an electrical ground M of the electric motor 4.

[0028] In one embodiment, the electric motor 4 comprises a conductive casing 16 which is connected to the electrical ground of the vehicle. The casing conductive 16 itself constitutes an electrical ground of the electric motor 4.

[0029] The outer metal casing 14A, 14B, 14C is for example made of steel or aluminum. Any other conductive metal can also be used.

[0030] As illustrated in schematic section in [Fig.l], each outer casing 14A, 14B, 14C has for example a rectangular profile, with rounded corners. For example, each single-pole connection box 6A, 6B, 6C is parallelepipedal in shape.

[0031] Each single-pole connection box 6A, 6B, 6C further comprises an inner casing 18A, 18B, 18C made of insulating material.

[0032] The term insulator refers to electrical insulation under normal conditions of use.

[0033] The insulating material is for example glass, particularly fiberglass or glass mat stiffened by a resin. Alternatively, the inner envelope 18A, 18B, 18C is made by a mica coating for example.

[0034] The inner casing 18A, 18B, 18C made of insulating material is placed between the walls of the outer casing 14A, 14B, 14C and the other elements of the single-pole connection box.

[0035] Each single-pole connection box further comprises a connection terminal (also known as a "lug") 20A, 20B, 20C which is electrically connected to a metal connection plate 22A, 22B, 22C, each metal connection plate being connected to a phase terminal of the electric motor. For example, the metal connection plate 22A, 22B, 22B is made of copper, and comprises a connection terminal 8, 10, 12 to a respective phase of the electric motor, each connection terminal 8, 10, 12 being in direct contact with the metal connection plate. For example, the phase connection terminal 8, 10, 12 is connected to the metal connection plate 22A, 22B, 22C by screwing;

[0036] The connection terminal 20A, 20B, 20C is also connected to a power cable 24A, 24B, 24C. For example, the power cables 24A, 24B, 24C are used to connect the connection assembly 2 to the inverter 26.

[0037] The inverter 26, which is a three-phase power supply device, comprises power supply terminals 30, 32, 34, each power supply terminal 30, 32, 34 being connected to a connection terminal 20A, 20B, 20C of the connection assembly 2, via the corresponding power cable 24A, 24B, 24C.

[0038] In addition, each single-pole connection box 6A, 6B, 6C comprises a fixing member 28A, 28B, 28C, adapted to fix the metal connection plate 22A, 22B, 22C to the corresponding connection terminal 20A, 20B, 20C. The fixing member 28A, 28B, 28C is for example a screw.

[0039] A hole (not visible in [Fig.l]) is drilled in the inner casing 18A, 18B, 18C made of insulating material to allow the passage of the power cable 24A, 24B, 24C.

[0040] In one embodiment, the envelope 18A, 18B, 18C made of insulating material has a thickness e which varies according to industrial production requirements.

[0041] According to a variant, the single-pole connection box 6A, 6B, 6C does not include a metal connection plate, but a nut in the form of an insert in the support, in which the connection terminal 8, 10, 12 of the corresponding phase conductor and the connection terminal 20A, 20B, 20C are connected. For example, a fixing member, such as a screw, is used to fix these connection terminals. In this embodiment, the connection member is thus shared.

Claims

Claims

1. Connection assembly for an electric traction motor, the electric traction motor being adapted to be powered by a three-phase electricity source and comprising three phase terminals, characterized in that it comprises a set of three separate single-pole connection boxes (6A, 6B, 6C), each single-pole connection box comprising a metal outer casing (14A, 14B, 14C) connected to an electrical ground of the electric motor, an inner casing (18A, 18B, 18C) made of insulating material, a connection terminal (8, 10, 12) to a phase of the traction motor and a connection terminal (20A, 20B, 20C) to a phase of an electricity source.

2. A connection assembly according to claim 1, wherein said metallic outer shell (14A, 14B, 14C) is made of steel.

3. A connection assembly according to claim 1, wherein said metallic outer shell (14A, 14B, 14C) is made of aluminum.

4. A connection assembly according to one of claims 1 to 3, wherein said insulating material is glass.

5. Connection assembly according to one of claims 1 to 3, in which the inner envelope (18A, 18B, 18C) is made by a mica coating.

6. Connection assembly according to one of claims 1 to 5, in which each single-pole connection box (6A, 6B, 6C) comprises a metal connection plate (22A, 22B, 22C), said connection terminal to one phase of the traction motor being connected to said connection plate, the assembly further comprising a fixing member (28A, 28B, 28C) adapted to fix the connection terminal (20A, 20B, 20C) to said connection plate.

7. An electric traction motor (4) adapted to be powered by a three-phase electricity source (26) and having three phase terminals, comprising a connection assembly according to claims 1 to 6, each phase terminal of the electric traction motor (4) being connected to a connection terminal (8, 10, 12) of a single-pole connection box (6A, 6B, 6C) of said connection assembly.

8. An electrically powered vehicle comprising an electric traction motor adapted to be powered by a three-phase electricity source (26) and comprising three phase terminals, comprising a connection assembly (2) according to claims 1 to 6, the vehicle comprising a three-phase power supply device (26) having three power supply terminals (30, 32, 34), each power supply terminal (30, 32, 34) being connected to a connection terminal (20A, 20B, 20C) of the connection assembly (2).

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