GB2603202A

GB2603202A - Bogie for a light rail system

Info

Publication number: GB2603202A
Application number: GB2101416.2A
Authority: GB
Inventors: Pemberton Martin; Salkeld Paul; Hall Matthew; Gustafsson Jorgen; Howson Adrian; Sozanski Antoni
Original assignee: Coventry City Council
Current assignee: Coventry City Council
Priority date: 2021-02-02
Filing date: 2021-02-02
Publication date: 2022-08-03
Anticipated expiration: 2041-02-02
Also published as: GB202101416D0; GB2603202B

Abstract

A bogie 100 for a rail-based vehicle, such as a train or tram. The bogie comprises one or more rail wheel arrangements 110, 120, each having two rail wheels 111, 112. The rail wheels are driven by a motor arrangement 130, comprising one or more electrical motors. The operation of the motor arrangement is controlled by alternating signals provided by an inverter arrangement 140 formed in the bogie. The inverter arrangements converts a direct current (power supply) to one or more alternating currents, or one or more alternating current power supplies, for controlling the torque applied by the electrical motor(s) of the motor arrangement. The inverter arrangement may comprise a separate inverter 141, 142 for each motor. The battery arrangement may be positioned externally to the bogie.

Description

BOGIE FOR A LIGHT RAIL SYSTEM

FIELD OF THE INVENTION

The present invention relates to the field of rail-based vehicles, and in particular, to bogies for use with rail-based vehicles.

BACKGROUND OF THE INVENTION

There is a long tradition of rail-based vehicles, such as a tram or train, which propel themselves along rail-based infrastructure, e.g. along one or more tracks coupled to a ground surface.

There has been a growing adoption of electric rail-based vehicles. Historically, electric rail-based vehicles draw power from an external (to the vehicle) power line that runs above, beside or underneath (e.g. as an electric ground rail) the tracks along which the vehicle travels. Electrical motors are then used to drive wheels of the rail-based vehicle. These wheels may be mounted, for example, upon a bogie fastened to an underside of a carriage for the rail-based vehicle.

There has been an increasing interest in the use of electric rail-based vehicles that contain batteries for powering electrical motors. These rail-based vehicles are sometimes called a battery electric railcar or battery electric multiple unit. The use of batteries avoids the need for external power lines.

There is an ongoing desire to improve the operation of rail-based vehicles, and in particular, rail-based vehicles that make use of batteries.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to examples in accordance with an aspect of the invention, there is provided a bogie for a rail-based vehicle. The bogie comprises: one or more rail wheel arrangements, each rail wheel arrangement comprising a first rail wheel; and a second, different rail wheel; a motor arrangement comprising one or more electrical motors configured to drive the rail wheels of each rail wheel arrangement; and an inverter arrangement.

The inverter arrangement is configured to: receive a direct current from a battery arrangement; convert the direct current into one or more alternating currents; and provide the one or more alternating currents to the one or more electrical motors of the motor arrangement to power the one or more electrical motors.

The present disclosure relates to a concept for positioning one or inverters (of an inverter arrangement), for an electric rail-based vehicle, upon the bogie(s) for the rail-based vehicle.

Positioning the inverter arrangement on the bogie itself helps reduce electromagnetic compatibility issues with the bogie, e.g. by reducing possible electromagnetic interference. In particular, it is recognized that an alternating current (AC) for a motor can cause large amounts of electromagnetic interference, EMI, due to the inherent undesirable impedances in a cable carrying such an alternating current. By positioning the inverter(s) on the bogie itself, the length of the cable carrying such an alternating current is reduced/minimized, thereby reducing the amount of shielding required and/or an amount of EMI.

Positioning an inverter arrangement on the bogie also facilitates independent testing and configuration of the bogies propulsion capabilities. In particular, the inverter arrangement can be configured independently of the rail vehicle, e.g. to tune the inverter arrangement for the specific bogie (and the specific requirements of the motor arrangements of the bogie). This facilitates a "plug-and-play" functionality for the bogie, reducing a configuration or tailoring that needs to be performed once the bogie is connected to the rail-based vehicle.

This approach thereby facilitates increased ease of installing a bogie and/or maintaining the electrical components of a bogie, i.e. providing a more modular rail-based vehicle. This desire for a more modular rail-based vehicle has been previously unnoticed or unrecognized in the rail industry, but facilitates reduced downtime and ease of maintenance. In the context of the present application, the terms "direct current-and -alternating current" are considered interchangeable with the terms "direct current supply" and -alternating current supply" respectively, or with the terms "direct voltage-and "alternating voltage" respectively, or with the terms "direct voltage supply" and "alternating voltage supply" respectively.

An alternative label for a bogie is a "truck", and the two terms are considered interchangeable.

In some examples, the inverter arrangement comprises, for each electrical motor of the motor arrangement, a respective inverter configured to receive the direct current from the battery arrangement and convert the direct current into an alternating current for the electrical motor.

A separate inverter for each motor facilitates improved control over the propulsion provided by the bogie. In particular, the separate converter can provide different levels of power for each motor, to facilitate distributed driving of the bogie (and a rail-based vehicle that makes use of such a bogie).

In some examples, the motor arrangement comprises, for each rail wheel set, a respective electrical motor configured to drive the rail wheels of the rail wheel set. Use of different electric motors for each rail wheel set facilitates the use of distributed torque techniques for the bogie.

Preferably, the one or more wheel arrangements comprises two or more rail wheel arrangements.

In at least one embodiment, the bogie further comprises a cooling system configured to cool the motor arrangement and the inverter arrangement. The cooling system may comprise any suitable coolant, e.g. air or water, for cooling the motor arrangement and the inverter arrangement. The cooling system may be confined to the bogie alone (i.e. may be mounted on and cool components of only a single bogie). The cooling system may draw power from the inverter arrangement, e.g. there may be a separate inverter for the cooling system.

Positioning the cooling system on the bogie alone further increases a modularity (as well as an ease of maintenance and bogie-replacement) of the overall rail-based vehicle, as it avoids the need for a coolant line to be connected to the bogie. This increases an ease of disconnecting a bogie from the rest of the rail-based vehicle.

The inverter arrangement may further comprise an inverter controller, configured to control the properties of the one or more alternating currents provided to the one or more electrical motors of the motor arrangement. The inverter controller may be responsive, for instance, to a user input provided at a control panel or user interface of the rail-based vehicle. The inverter controller may therefore be adapted to receive, at an input interface, an input signal, and control the one or more alternating currents provided to the one or more electrical motors responsive to the input signal (effectively controlling a propulsive force provided by the bogie).

The input signal may, for instance, define a desired torque to be applied by the one or more electrical motors to the respective rail wheel arrangements, and may be provided from a vehicle control system (e.g. via a Control Area Network (CAN) bus). This input signal may be responsive to a user input provided at a user interface or control panel (e.g. to achieve a desired speed or the like).

The inverter controller may also be responsive to diagnostic information, current and voltage measurements (i.e. feedback), temperature sensing inputs and the like.

Approaches for controlling the operation of an inverter and motor arrangement based on such information will be readily apparent to the skilled person.

Preferably, the inverter arrangement is configured to receive the direct current from a battery arrangement positioned externally to the bogie.

The inverter arrangement may be positioned towards the center of the bogie. In other words, the inverter arrangement may be positioned closer to the center of the bogie than to an outer edge of the bogie.

Preferably, all inverters of the inverter arrangement are positioned adjacent to one another, e.g. side by side.

There is also proposed a rail-based vehicle comprising two or more bogies as herein described. The rail-based vehicle may further comprise a battery arrangement configured to provide a direct current to the inverter arrangement of each bogie. Preferably, the battery arrangement is separate to the two or more bogies.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figures 1 and 2 illustrate a bogie according to an embodiment; and Figure 3 illustrates a rail-based vehicle according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will be described with reference to the Figures.

It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

The invention provides a bogie for a rail-based vehicle, such as a train or tram.

The bogie comprises one or more rail wheel arrangements, each having two rail wheels. The rail wheels are driven by a motor arrangement, comprising one or more electrical motors. The operation of the motor arrangement is controlled by alternating signals provided by an inverter arrangement formed in the bogie. The inverter arrangement converts a direct current (power supply) to one or more alternating currents, or one or more alternating current power supplies, for controlling the torque applied by the electrical motor(s) of the motor arrangement.

The inventors have recognized an advantage to positioning an inverter (arrangement) for the electrical motor(s) of a bogie upon the bogie itself This reduces the length of cables carrying alternating current(s) for the electrical motor(s), e.g, to reduce an amount of material required and/or to reduce electromagnetic interference provided by such cables carrying alternating signals. This approach also facilitates testing and tuning of the inverter for the specific motor arrangement of the bogie independently of the rail-based vehicle (e.g, only needing the bogie, without needing the rest of the rail-based vehicle), to facilitate improved ease in maintaining and replacing bogies.

Effectively, the present invention recognizes a benefit in placing the inverters for electric-based vehicles upon the bogies of the vehicles, rather than externally to the bogies (e.g, together with the battery arrangement that stores power for driving the motor arrangement(s)).

Figures 1 and 2 illustrate a bogie 100 according to an embodiment of the invention. The bogie is designed for a rail-based vehicle, e.g, a carriage, train or tram. The rail-based vehicle may comprise a plurality of such bogies, as would be readily apparent to the skilled person.

Figure 1 provides an exploded view of the bogie 100, and Figure 2 provides a top-down view of the bogie 100.

The bogie 100 may be configured to carry and/or support a carriage for the rail-based vehicle thereon The bogie 100 comprises a first rail wheel arrangement 110 and a second rail wheel arrangement 120. The skilled person would appreciate that the bogie may be adapted to comprise only a single rail wheel arrangement or more than two rail wheel arrangements. C)

The first 110 and second 120 rail wheel arrangements are near-identical, differing primarily in their positions on the bogie. For the sake of conciseness, only a single one of these rail wheel arrangements will be hereafter described, although the other rail wheel arrangement may comprise similar/corresponding elements.

The first rail wheel arrangement 110 comprises a first rail wheel 111 and a second rail wheel 112. A rail wheel is a wheel that is configured/designed for use on a railway track. The rail wheels III, 112 are connected via a rail wheel axle. The rail wheel axle may, as illustrated, be a split wheel axle which effectively forms a first rail wheel axle and a second rail wheel axle, which are connected together by a differential, such as an open differential.

However, in other examples, the rail wheels 111, 112 may be connected by a single, unified rail wheel axle (i.e. so that the rail wheels 111, 112 are controlled so as to rotate at a same speed).

The bogie 100 also comprises a motor arrangement 130. The motor arrangement comprises one or more electrical motors configured to drive the rail wheels of each rail wheel arrangement. In the illustrated example, the motor arrangement HO comprises an electrical motor for each wheel arrangement, i.e. a first electrical motor 131 and a second electrical motor 132.

The electrical motor(s) are configured to control the rotation of the rail wheels, i.e, drive the rail wheels. The electrical motor(s) may control the rotation of the rail wheels using any suitable control mechanism, e.g. via one or more gearboxes and/or differentials.

Suitable mechanisms for facilitating control of rail wheel rotations using electric motors will be readily apparent to the skilled person.

The bogie 100 also comprises an inverter arrangement 140. The inverter arrangement 140 is configured to provide one or more alternating currents to the motor arrangement 130. In particular examples, the inverter arrangement is configured to provide a different alternating current (or set of alternating currents -e.g, three alternating currents for providing a three-phase power supply) to each electrical motor 131, 132 of the motor arrangement 130.

In particularly preferable examples, the inverter arrangement 140 comprises a separate inverter 141, 142 for each electrical motor of the motor arrangement. For instance, a first inverter 141 may be configured to control the operation of the first electrical motor 131, and a second inverter 142 may be configured to control the operation of the second electrical motor 132.

The properties of the alternating current(s) define the torque supplied by each electrical motor of the motor arrangement for driving the rail wheels. In particular, a magnitude of the current and/or voltage of the alternating current(s) supplied by the inverter arrangement to the motor arrangement controls or otherwise defines the torque provided or supplied by the electrical motor(s).

In particular, the inverter arrangement is configured to receive a direct current (supply) from a battery arrangement, which may be positioned separately or externally to the bogie itself (i.e. "off-board"). For instance, the battery arrangement may be mounted upon other parts of a rail-based vehicle comprising the bogie -e.g. the carriage of the rail-based vehicle.

This effectively means that a bogie can be simply coupled to a carriage (i.e. the remainder of the rail-based vehicle) and connected with a power supply (provided by a battery) and control wires/cables in order to correctly operate (e.g. rather than needing to connect to a potential complex inverter output). This facilitates increased ease in installing, removing and/or maintaining a bogie, as it can be readily separated from the rest of the rail-based vehicle. Put another way, the proposed bogie facilitates an improved, more modular rail-based vehicle (i.e. in which parts or components can be readily replaced).

The inventive concept is particularly advantageous when the inverter arrangement provides a set of (at least three) alternating currents to each electrical motor, i.e. when the electrical motor(s) is configured to operate using at least three alternating currents as input (i.e. three-phase design). In particular, a direct current supply is usually carried over two cores/cables (one to provide a high voltage, and one to provide a ground/reference voltage). If the inverter arrangement is configured to provide a set of at least three alternating currents (to each electrical motor), then the amount of cable/core required to provide the electrical motor is reduced when the inverter is located in the bogie, compared to if the inverter arrangement is external to the bogie, as the inverter arrangement will be more proximate to the electrical motor(s), thereby requiring a reduced amount of cabling. This is because at least one less cable/core will be provided from outside of the bogie to within the confines of the bogie.

The inverter arrangement 140 may comprise one or more inverter controllers, configured to control the properties of the one or more alternating currents provided to the one or more electrical motors of the motor arrangement. In some examples, each inverter (of the inverter arrangement) comprises a separate inverter controller.

In particular, and as previously explained, it will be appreciated that the properties of the one or more alternating currents provided to the electrical motor(s) of the motor arrangement 130 define an operation of the electrical motor(s), e.g. define a torque applied by the electrical motor(s) and thereby a propulsive force and/or rotation speed of the rail wheels 111, 112. In particular, the magnitude of a current and/or voltage supplied by the inverter arrangements to the electrical motor(s) defines the torque provided by the electrical motor(s). Typically, the greater the power of the alternating current(s) supplied to the motor arrangement, the greater the torque applied by the motor arrangement.

The inverter controller(s) thereby controls the (magnitude of the) propulsive force provided by the bogie 100, and thereby the speed of the overall rail-based vehicle comprising the bogie.

The inverter controller may be responsive to one or more input signals, e.g. received at an input interface of the inverter controller.

At least one input signal may be provided by an external vehicle control system, e.g. which controls or defines a desired operation for the motor arrangement -e.g. defining a torque to be provided by each motor to the rail wheels. The input signal may, for example, be responsive to a user input received at a user interface of the rail-based vehicle, to allow a user to control the operation/speed of the rail-based vehicles. The input signal may be received by the inverter controller via a Control Area Network (CAN) bus, using approaches well known to the skilled person.

The one or more input signals may further comprise signals carrying additional information, such as diagnostic information, current and voltage measurements (e.g. feedback information), temperature information and the like. This additional information aids in the accurate provision of a desired torque by the electrical motor(s), as would be readily apparent to the skilled person.

Mechanisms and schemes for controlling the speed of a rail-based vehicle by controlling the operation of inverters for electrical motor(s) of bogies are well known and

established in the prior art.

The bogie may comprise a cooling system (not visible) configured to cool the motor arrangement and the inverter arrangement. The cooling system may, for example, be a water-cooling system, which may require a radiator with a fan and/or a water pump. However, other suitable coolants (e.g. gaseous coolants such as air) could be used.

Preferably, all the components located in the bogie are cooled using the same cooling system. In some examples, the cooling system may be confined to the (single) bogie -i.e. may be unconnected from other components of a rail-based vehicle comprising the bogie. It is recognized that confining a cooling system to a bogie facilities increased ease in connecting and disconnecting a bogie (e.g. for maintenance or repair), e.g. as there will be no need to disconnect a coolant supply from the bogie. This facilitates a further improved "plug and play" functionality of the bogie.

It is recognized that positioning the inverters on the bogie itself (e.g. rather than externally to the bogie) means that the cooling system required for a powertrain of a single bogie can be confined to the bogie itself reducing an amount of cooling system elements needed to be positioned off-board from the bogie.

The various components of the bogie 100 may be mounted on a bogie frame 150, sometimes called a chassis or framework. The bogie frame 150 is also configured or arranged to be fastenable to a carriage, train or tram (not shown), i.e. the rest of the rail-based vehicle.

The bogie frame 150 may connect to the carriage via a bolster 153 and a fastening mechanism 155. The fastening mechanism 155 may be configured to rotate with respect to a connected carriage, e.g. the fastening mechanism may allow the bogie 100 to rotate about some predetermined axis. Thus, the fastening mechanism 155 may comprise a fulcrum or pivot pin (sometimes called a center pin). However, the use of a rotatable fastening system is not essential, and the bogie may instead be fixedly secured to the remainder of the rail-based vehicle.

The fastening arrangement 155 is not visible in Figure 2.

In some examples, the fastening arrangement 155 is configured to allow the passage of cables, e.g. control cables or cables carrying the direct current, to the components of the bogie.

In some such examples, the inverter may be positioned proximate or adjacent to the fastening arrangement, in order to reduce or minimize the amount of cabling required (and thereby reduce potential electromagnetic interference caused by lengthy cables as well as improving efficiency by reducing potential loss of energy, e.g. due to impedances in the cables and the like).

Just as the fastening arrangement 155 may be positioned towards a center of the bogie (e.g. to facilitate improved ease of following the curvature of the track and to maximize a support provided by the bogie), so the inverter arrangement 140 may be positioned towards a center of the bogie.

In particular, if a horizontal plane of the bogie is conceptually divided into a 3x3 grid, the center of the inverter arrangement may be positioned in the central column and central row of the 3x3 grid. The horizontal plane is a plane which, when the bogie is placed on flat ground, is parallel to the flat ground.

Other suitable components of a bogie will be readily apparent to the skilled person, and may include (amongst others) a suspension arrangement, a braking arrangement).

A full description of such components is omitted for the sake of conciseness, and to emphasize the inventive concept of the present invention.

Figure 3 illustrates a rail-based vehicle 300 according to an embodiment. The rail based vehicle comprises a plurality of bogies 100, and in the illustrated example, comprises two bogies.

The rail-based vehicle 300 may further comprise a battery arrangement 310. The battery arrangement may be configured to provide (direct current) power to the inverter arrangement (of each of the bogies 100). The battery arrangement 310 may be configured to connect to the inverter arrangement over one or more power cables (not shown), which may be designed for carrying high voltages. These voltages may be in the region of 500V to 800V, e.g. up to no more than 750V, e.g. up to around 710V.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS: A bogie for a rail-based vehicle, the bogie comprising: one or more rail wheel arrangements, each rail wheel arrangement comprising a first rail wheel; and a second, different rail wheel; a motor arrangement comprising one or more electrical motors configured to drive the rail wheels of each rail wheel arrangement; and an inverter arrangement configured to: receive a direct current from a battery arrangement; convert the direct current into one or more alternating currents; and provide the one or more alternating currents to the one or more electrical motors of the motor arrangement to power the one or more electrical motors.
2. The bogie of claim 1, wherein the inverter arrangement comprises, for each electrical motor of the motor arrangement, a respective inverter configured to receive the direct current from the battery arrangement and convert the direct current into an alternating current for the electrical motor.
3. The bogie of any of claims 1 or 2, wherein the motor arrangement comprises, for each rail wheel set, a respective electrical motor configured to drive the rail wheels of the rail wheel set.
4. The bogie of any of claims 1 to 3, wherein the one or more wheel arrangements comprises two or more rail wheel arrangements.
5. The bogie of any of claims 1 to 4, further comprising a cooling system configured to cool the motor arrangement and the inverter arrangement.
6. The bogie of any of claims 1 to 5, wherein the inverter arrangement further comprises an inverter controller, configured to control the properties of the one or more alternating currents provided to the one or more electrical motors of the motor arrangement 7. The bogie of any of claims I to 6, wherein the inverter arrangement is configured to receive the direct current from a battery arrangement positioned externally to the bogie.8. The bogie of any of claims 1 to 7, wherein the inverter arrangement is positioned towards the center of the bogie 9. A rail-based vehicle comprising two or more bogies according to any of claims 1 to 8.10. The rail-based vehicle of claim 9, further comprising a battery arrangement configured to provide a direct current to the inverter arrangement of each bogie.1 1. The rail-based vehicle of claim 10, wherein the battery arrangement is separate to the two or more bogies.