GB2566499A

GB2566499A - Regenerative braking arrangement for electrical vehicles

Info

Publication number: GB2566499A
Application number: GB1714892.5A
Authority: GB
Inventors: lam Albert
Original assignee: DE Innovation Lab Ltd
Current assignee: DE Innovation Lab Ltd
Priority date: 2017-09-15
Filing date: 2017-09-15
Publication date: 2019-03-20
Anticipated expiration: 2037-09-15
Also published as: WO2019053675A2; GB201714892D0; GB2566499B; WO2019053675A3

Abstract

A regenerative braking arrangement for an electric vehicle (e.g. EV, HEV, PHEV, BEV) includes: at least one electric motor having a rotor 208 and casing-mounted stator 204; and a motor control arrangement. The stator includes one or more planar (plate-like or disk-like) elements 204A, 204B extending from the casing 202. The rotor has one or more planar elements 208A, 208B attached to a shaft 210 that is disposed within a central hole 206 of each planar stator element. A magnetic separation gap 212 is present between the stator and rotor elements. The planar stator and rotor elements include electric winding coil arrangements 214A, 214B, 216A, 216B (e.g. printed circuit board (PCB) conductive tracks) having a regenerative braking coil arrangement 218A, 218B. The regenerative braking coil arrangement may be arranged on a first side of the planar stator element(s) with the stator coil arrangement arranged on a second, opposite side of the stator element. The motor control arrangement includes a rotor excitation unit and a switching control unit that selectively couples the regenerative braking coil arrangement for generating electrical power from the motor via regenerative braking in order to recharge the rechargeable battery.

Description

REGENERATIVE BRAKING ARRANGEMENT FOR ELECTRICAL

VEHICLES

TECHNICAL FIELD

The present disclosure relates generally to electrical vehicles; more specifically, the present disclosure relates to regenerative braking arrangements for electrical vehicles.

BACKGROUND

Electrical vehicles are potentially capable of playing a significant role in reducing environmental pollution and encouraging sustainable technologies. Typically, the electrical vehicles produce fewer by-products that cause anthropogenic climate change in comparison to conventional vehicles powered by fossil fuels. However, it has been appreciated that electrical vehicles with efficient methods of power utilization have to be manufactured to encourage the use of electrical vehicles in place of corresponding-performance internal combustion engine vehicles. Furthermore, power utilization of the electrical vehicle may be significantly improved by employing regenerative braking therein.

Typically, regenerative braking in an electrical vehicle is achieved by harvesting kinetic energy of the vehicle that may otherwise be lost as heat during frictional braking of the vehicle. Specifically, the harvested kinetic energy may be used to recharge a battery of the electrical vehicle. Conventionally, a regenerative braking system may include a generator that may generate electrical power from the kinetic energy of the vehicle. Subsequently, the electrical power may be supplied to the battery of the electrical vehicle. Such a complex arrangement of regenerative braking system may lead to energy losses during transmission of electrical power to the battery. More recently, a motor arrangement of the electrical vehicle may be reversed in operation to function as a generator to harvest the kinetic energy. However, such a motor arrangement may comprise complex electrical winding coils that may potentially lead to overheating and power dissipation therein.

Therefore, in light of the foregoing discussion, there is a need to overcome the aforementioned drawbacks associated with regenerative braking system employed in electrical vehicles.

SUMMARY

The present disclosure seeks to provide an improved regenerative braking arrangement for an electrical vehicle.

According to an aspect, an embodiment of the present disclosure provides a regenerative braking arrangement for an electrical vehicle, characterized in that the regenerative braking arrangement includes:

(i) at least one electrical motor including

- a casing,

- a stator mounted on the casing, the stator includes one or more planar stator elements extending from the casing, wherein each of the one or more planar stator elements includes a central hole, and

- a rotor including

- a shaft that is disposed within the central hole of each of the one or more planar stator elements of the stator, and

- one or more planar rotor elements attached to the shaft,

- wherein principal planes of the one or more planar stator and rotor elements are arranged mutually to abut with a magnetic separation gap therebetween, and the one or more planar stator and rotor elements are arranged to have electrical winding coil arrangements disposed thereon, and wherein the electrical winding coil arrangements include a regenerative braking coil arrangement, and

- magnetic bearings coupled to ends of the shaft of the rotor; and (ii) a motor control arrangement including

- a rotor excitation unit to couple electrical power from a rechargeable battery arrangement of the electrical vehicle to a resonant inductive power coupling arrangement, wherefrom the electrical power is coupled wirelessly to the rotor of the at least one electrical motor, and

- a switching control unit for selectively energizing the regenerative braking coil arrangement for generating electrical power from the at least one electrical motor when regenerative braking is applied in operation to recharge the rechargeable battery arrangement of the electrical vehicle.

The present disclosure seeks to provide an improved regenerative braking arrangement for an electrical vehicle; moreover, the regenerative braking system provides an efficient, inexpensive system for harvesting kinetic energy of the electrical vehicle.

It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

The present invention is included in the general business context, which aims to substitute vehicles powered by traditional fuels, for example gasoline or diesel, by electric vehicles. In particular, the present invention is intended for use in electric vehicles used within cities, which can be highly beneficial to the local environment due to significant reduction of gaseous emissions as well as significant reduction of noise. Overall environmental benefits can also be significant when electric vehicles are charged from renewable energy sources.

DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

FIG. 1 is a schematic illustration of an electrical vehicle having a regenerative braking arrangement, in accordance with an exemplary embodiment of the present disclosure;

FIG. 2 is a schematic illustration of an electrical motor of the regenerative braking arrangement of FIG. 1, in accordance with an exemplary embodiment of the present disclosure; and

FIG. 3 is a schematic illustration of electrical architecture for the regenerative braking arrangement of FIG. 1, in accordance with an exemplary embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

DESCRIPTION OF EMBODIMENTS

In overview, embodiments of the present disclosure are concerned with regenerative braking arrangements of electrical vehicles.

Referring to FIG. 1, shown is a schematic illustration of an electrical vehicle 100 having a regenerative braking arrangement 102, in accordance with an embodiment of the present disclosure. As shown, the electrical vehicle 100 comprises a vehicle frame 104 and a rechargeable battery arrangement 106 for storing energy. The regenerative braking arrangement 102 includes at least one electrical motor, such as an electrical motor 110, and a motor control arrangement 120 for controlling an electrical power flow between the rechargeable battery arrangement 106 and the electrical motor 110. The motor control arrangement 120 includes a rotor excitation unit 122 and a switching control unit 124, which will be explained in greater detail hereinafter in conjunction with subsequent figures.

According to an embodiment, the electrical vehicle 100 is shown to be driven by rear wheels 130 with the help of the electrical motor 110. For example, the electrical motor 110 is operable to drive the rear wheels 130 via a driveshaft 132 linked to a rear axle 134 by a differential gear arrangement 136. Alternatively, the electrical vehicle 100 may include multiple motors, i.e. individual motors operatively coupled to each of the rear wheels 130. In another embodiment, the electrical vehicle 100 may also include multiple motors, i.e. individual motors operatively coupled each to front wheels 140. Furthermore, the motors may be one of wheel hub motors or motors mounted on the vehicle frame 104. In one example, the electrical vehicle 100 includes two-wheel hub motors coupled to each of the front wheels 140 and two motors coupled to each of the rear wheels 130 mounted on the vehicle frame 104 (such that the motors form a part of sprung weight of the electrical vehicle 100).

Referring to FIG. 2, illustrated is a schematic illustration of the electrical motor 110 of the regenerative braking arrangement 102 of FIG. 1, in accordance with an exemplary embodiment of the present disclosure. The electrical motor 110 includes a casing 202. In one example, the casing 202 is implemented as a hollow cylindrical structure that is operable to accommodate the components of the electrical motor 110. Furthermore, in an example, the casing 202 is fabricated using an aluminum (aluminium) sheet. Such fabrication of the casing 202 using the aluminum sheet enables to provide a lightweight structure that is associated with a low manufacturing cost, while enabling convenient dissipation of heat generated during operation of the electrical motor 110. In another example, the casing 202 is fabricated using a steel sheet.

Furthermore, the electrical motor 110 includes a stator 204 mounted on the casing 202. The stator 204 is a stationary component of the electrical motor 110. Furthermore, the stator 204 is operable to provide a magnetic field to enable operation of one or more components of the electrical motor 100 (such as a rotor). The stator 204 includes one or more planar, for example plate-like, stator elements 204A-B extending from the casing 202, wherein each of the one or more planar stator elements 204A-B includes a central hole 206. In one example, the one or more planar stator elements 204A-B is fabricated using fiberglass, carbon fiber, fiber-reinforced resin composite or similar. Furthermore, the one or more planar stator elements 204A-B are attached to an inside of the casing 102. In one example, the one or more planar stator elements 204A-B are implemented as semi-circular half plates that are operable to be arranged to form the one or more planar stator elements 204A-B. For example, the casing 202 is implemented as a semi-cylindrical structure and furthermore, the one or more planar stator elements 204A-B are formed as an integral part of the casing 202. Such implementation of the one or more planar stator elements 204A-B

Ί enables easy accommodation of one or more components (such as a rotor shaft) of the electrical motor 110 and consequently, convenient assembly (and/or disassembly) of the electrical motor 110.

The electrical motor 110 further includes a rotor 208. The rotor 208 is a rotatable component of the electrical motor 110 that enables to generate torque, for example, for rotating one or more wheels associated with the electrical vehicle. In an embodiment, the rotor 208 is operable to rotate at a maximum rotation rate in a range of 30000 rotations per minute (r.p.m.) to 100000 rotations per minute (r.p.m.). It will be appreciated that such high rotation rate of the rotor 208 enables a high speed operation of the electrical motor 110.

The rotor 208 includes a rotor shaft 210 that is disposed within the central hole 206 of each of the one or more planar stator elements 204AB of the stator 204. For example, the rotor shaft 210 is implemented as a cylindrical rod that is operable to rotate around an axis (such as an axis passing through center of the cylindrical rotor shaft). Furthermore, the rotor 208 includes one or more planar, for example plate-like, rotor elements 208A-B attached to the rotor shaft 210. In one example, the one or more planar rotor elements 208A-B are fabricated using fiberglass, carbon fiber, fiber-reinforced resin composite or similar. Furthermore, the one or more planar rotor elements 208A-B are attached to the rotor shaft along the axis thereof.

Optionally, the one or more planar stator elements and the one or more planar rotor elements are provided with paramagnetic cores for providing a low magnetic reluctance path for magnetic fields generate by the one or more planar stator elements and the one or more planar rotor elements. The paramagnetic cores are beneficially manufactured from a ferromagnetic material, for example a ferrite material or a laminate structure including a plurality of layers of ferromagnetic material (for example silicon steel sheets as employed in electrical transformers).

Beneficially, the paramagnetic cores have a low electrical conductivity so as to reduce eddy current induction therein when the one or more planar stator elements and the one or more planar rotor elements are subjected to temporally changing magnetic fields when in operation.

Furthermore, in operation, heat may be generated in the electrical motor 110, for example, due to resistance (or drag) of the rotating rotor 208 against air within the electrical motor 110, flow of electrical power through one or more components of the electrical motor 110, and so forth. In such an instance, providing one or more planar stator elements 204A-B and the one or more planar rotor elements 208A-B enables improved air flow (such as, between the one or more planar stator and rotor elements) within the electrical motor 110. Consequently, the improved air flow within the electrical motor 110 to be air cooled, thereby, reducing a requirement of external cooling arrangements to be accommodated therein. It will be appreciated that such air cooled electrical motor 110 can be arranged in a lightweight and compact design and furthermore, will be associated with low manufacturing cost (due to reduced costs associated with cooling arrangements). Additionally, such air cooling enables high speed operation of the electrical motor 110, further allowing high speed operation of the electrical vehicle (for example, the electrical vehicle may be driven at high speeds).

Moreover, principal planes of the one or more planar stator elements 204A-B and rotor elements 208A-B are arranged mutually to abut with a magnetic separation gap 212 therebetween. For example, the one or more planar rotor elements 208A-B are attached to the rotor shaft 210 such that the one or more planar rotor elements 208A-B are positioned alternately with the one or more planar stator elements 204A-B of the stator 204. In such an instance, it will be appreciated that the one or more planar stator elements 204A-B do not obstruct the rotation of the rotor 208 as the one or more planar rotor elements 208A-B of the rotor

208 are disposed in a gap (forming the magnetic separation gap 212) formed by two adjacent planar stator elements 204A-B. For example, the magnetic separation gap 212 is defined by distance between principal surface planes of the one or more planar stator elements 204A-B and the one or more planar stator elements 208A-B (such as, flat planes of the one or more planar stator elements 204A-B and the one or more planar stator elements 208A-B facing each other). According to an embodiment, the magnetic separation gap 212 is in a range of 0.3 mm to 10.0 mm, and more optionally in a range of 0.5 mm to 5.0 mm. In one example, the magnetic separation gap 212 is 1.0 mm. In another example, the magnetic separation gap is 4.5 mm.

Moreover, the one or more plate-like stator elements 204A-B and the one or more plate-like rotor elements 208A-B are arranged to have electrical winding coil arrangements disposed thereon. In one example, each of the one or more planar stator elements 204A-B are arranged to have a stator coil arrangement 214A and 214B respectively, disposed thereon. Such stator coil arrangements 214A-B enables to provide the magnetic field to enable the rotation of the rotor 208. In an embodiment, the stator coil arrangements 214A-B (i.e. electrical winding coil arrangements) are implemented using printed circuit board conductive tracks. For example, the one or more planar stator elements 204A-B is implemented as a printed circuit board that is fabricated using fiberglass. In such an instance, the stator coil arrangements 214A-B are implemented as copper conductive tracks that are lithographically (for example, using optical lithography) printed or etched on the printed circuit board. Furthermore, such conductive tracks associated with the one or more planar stator elements 204A-B enable a flow of electrical current therethrough. Such flow of electrical current through the conductive tracks enables the stator 204 to function as an electromagnet for providing the magnetic field for rotation of the rotor 208.

In an embodiment, the electrical motor 110 includes non-permanentmagnet ferrite elements, for example the aforementioned paramagnetic cores, for defining a torque-generating magnetic field for the electrical motor 110 when in operation. In one example, the non-permanentmagnet ferrite elements are implemented as unmagnetized ferrite cores within the one or more planar stator elements 204A-B. For example, the unmagnetized ferrite cores are implemented as a ferromagnetic ferrite plate-like element that is incorporated (or sandwiched') between layers comprising each of the one or more planar stator elements 204AB. In one example, there is employed a ferromagnetic ferrite planar element is fabricated using silicon steel. In another example, the ferromagnetic ferrite or silico steel planar element has thickness in a range of 100 micrometers (pm) to 1000 micrometers (pm). In such an instance, the unmagnetized ferrite cores enable to provide a low reluctance path for the magnetic field associated with the stator 204. It will be appreciated that the magnetic field is provided orthogonally to principal surface planes of the one or more planar stator elements and rotor elements. According to an embodiment, the unmagnetized ferrite cores have a relative permeability (μ_Γ) in a range of 10 to 3000 and more optionally, in a range of 100 to 1000. In one example, the unmagnetized ferrite cores are fabricated from iron alloy powder, by using a technique such as powder sintering. In such an instance, an electrical conductivity associated with the unmagnetized ferrite cores is low as compared to the relative permeability thereof, to reduce magnetic hysteresis associated with the provided magnetic field and/or to reduce induced eddy currents associated with electrical power provided to the stator coil arrangements 214A-B.

In an example, each of the one or more planar rotor elements 208A-B are arranged to have a rotor coil arrangements 216A and 216B respectively, disposed thereon. According to an embodiment, the rotor coil arrangements 216A-B are implemented using printed circuit board conductive tracks. For example, the one or more plate-like rotor elements 208A-B is implemented as printed circuit boards that are fabricated using fiberglass. In such an instance, the rotor coil arrangements 216A-B is implemented as conductive tracks that are lithographically printed or formed by etching on the printed circuit board. In one example, the printed circuit board includes copper conductive tracks. Furthermore, the electrical winding coil arrangements for the one or more planar stator and rotor elements 204A-B, 208A-B include a regenerative braking coil arrangement. Specifically, regenerative braking coil arrangement, such as the regenerative braking coil arrangement 218A, 218B, are arranged on the one or more planar stator elements 204A-B. Furthermore, the regenerative braking coil arrangements 218A, 218B are arranged on a first side of the one or more planar stator elements 204A-B, and the stator coil arrangements 214A-B are arranged on a second side, opposite to the first side, of the one or more planar stator elements 204A-B.

The electrical motor 110 includes magnetic bearings 220A-B coupled to ends of the rotor shaft 210. For example, the rotor 208 is operable to rotate at high maximum rotation rates, such as, in a range of 30000 rotations per minute (r.p.m.) to 100000 rotations per minute (r.p.m.). In such an instance, the magnetic bearings are operable to prevent physical contact between the rotor shaft 210 and one or more other components of the electrical motor 110, such as, the one or more planar stator elements 104A-B. As shown, the magnetic bearings 220A-B include rings that are coupled to the rotor shaft 210 at two ends thereof. Furthermore, the magnetic bearings 220A-B include rings that are coupled to the stator 204 opposite to the rings coupled to the rotor shaft 210. In such an instance, the rings coupled to the rotor shaft 210 and the rings coupled to the stator 204 are associated with same magnetic poles (such as magnetic north poles or magnetic south poles). It will be appreciated that providing such same magnetic poles on the magnetic bearings 220A-B enables to maintain a gap between the rotor 208 and the stator 204 using magnetic levitation (such as, by magnetic repulsion therebetween). In an embodiment, the magnetic bearings 220A-B include a permanent magnet. For example, the magnetic bearings 220AB includes a rare-earth magnet. In one example, the rare-earth magnet is a neodymium magnet.

According to one embodiment, the rotor 208 of the electrical motor 110 is further provided with mechanical bearings 222A-B that bears the rotor 208 relative to the stator 204 when the magnetic bearings 220A-B are loaded to cause at least a portion of a gap of the magnetic bearings 220A-B to be mechanically contacted. For example, at the high speed operation of the electrical motor 110 due to the high rotation rate of the rotor 208, a load on the rotor shaft 210 increases. Consequently, a load associated with the magnetic bearings 220A-B increases. In such an instance, the gap between the rotor 208 and the stator 204 decreases, leading to a bottoming out condition of the magnetic bearings 220A-B (such as a condition associated with physical contact of the rings coupled to the rotor shaft 210 and the stator 204 respectively). In such an instance, the mechanical bearings 222A-B enable to reduce friction associated with the physical contact of the rings of the magnetic bearings 220A-B. In one example, the mechanical bearings 222A-B include a ball-race bearing arrangement. In such an instance, rotation of the rotor 208 is supported by rolling of a plurality of balls on races associated with the ball-race bearing arrangement. In another example, the mechanical bearings 222A-B include a roller-race bearing arrangement. In such an instance, rotation of the rotor 208 is supported by rolling of a plurality of rollers on races associated with the roller-race bearing arrangement.

In one embodiment, the electrical motor 110 includes a plurality of ferrite spacer rings 224A-B. For example, the ferrite spacer rings 224A-B are arranged between the one or more plate-like stator elements 204A-B.

In such an instance, the plurality of ferrite spacer rings 224A-B further enables to provide the magnetic field substantially orthogonally to the principal surface planes of the one or more planar stator elements 204AB and the one or more planar rotor elements 208A-B.

Referring to FIG. 3, there is shown a schematic illustration of an electrical architecture 300 for the regenerative braking arrangement 102 of FIG. 1, in accordance with an exemplary embodiment of the present disclosure. It will be appreciated that the electrical architecture 300 relates to a circuit configuration implemented for operation the regenerative braking arrangement 102. As shown, the electrical architecture 300 includes the rechargeable battery arrangement 106. Furthermore, the regenerative braking arrangement 102 is shown to includes an electrical motor, such as the electrical motor 110 of FIGs. 1 and 2, particularly, the electrical motor is shown to be implemented with the help of a rotor 302 and a stator 304. It will be appreciated that the rotor 302 and the stator 304 correspond to the rotor 208 and stator 204, respectively, shown and explained in conjunction with FIG. 2. Moreover, the electrical motor may also include other elements, such as a shaft, magnetic bearings and the like, not shown in schematic electrical architecture 300 of FIG. 3. The regenerative braking arrangement 102 also includes a motor control arrangement, such as the motor control arrangement 120 of FIG. 1, particularly, the motor control arrangement is shown to be implemented with the help of the rotor excitation unit 122 and the switching control unit 124. It will be appreciated that the motor control arrangement may also include other electronic elements and software modules that are not shown in FIG. 3. For example, the motor control arrangement may relate to hardware, software, firmware, or a combination of these, operable to control operation of the at least one electrical motor.

The rotor excitation unit 122 is operable to couple electrical power from the rechargeable battery arrangement 106 to a resonant inductive power coupling arrangement 306, wherefrom the electrical power is coupled wirelessly to the rotor 302. The resonant inductive power coupling arrangement 306 is operable to provide resonant inductively coupled power to the rotor 302 (such as the rotor 208 of FIG. 2). Subsequently, a current return of the rotor excitation unit 122 then feeds to a negative terminal of the rechargeable battery arrangement 106 via a stator 304 (such as the stator 204 of FIG. 2).

In one embodiment, the rotor excitation unit 122 is operable to convert a direct current (DC) from the rechargeable battery arrangement 106 into an alternating current (AC) that is to be coupled to the resonant inductive power coupling arrangement 306. Optionally, the rotor excitation unit 122 includes a resonant oscillator circuit, wherein the resonant oscillator circuit includes a tunable capacitor, a transformer including a primary winding and a secondary winding, and two push-pull transistors and. In such an instance, the tunable capacitor and primary winding of the transformer constitute a tank circuit that is tunable to a resonant frequency. Optionally, the transformer is implemented as a compact ferrite ring core transformer. Furthermore, optionally, the two push-pull transistors and are driven in mutual anti-phase at the resonant frequency of the resonant oscillator circuit. More optionally, the two pushpull transistors and are implemented by way of silicon carbide transistors.

Optionally, the resonant oscillator circuit of the rotor excitation unit 122 operates in a frequency range of 50 kilohertz to 1 megahertz. In such an instance, a frequency of the alternating current (AC) that is to be coupled to the resonant inductive power coupling arrangement 306 lies within the aforesaid frequency range. A subset of the one or more planar stator elements and the one or more planar rotor elements are provided with coil arrangements for enabling resonant inductor power coupling to occur wirelessly to the rotor 302.

Optionally, a bypass capacitor is provided across the rotor excitation unit 122, in order to remove stray alternating current noise within the direct current provided from the rechargeable battery arrangement 106. Beneficially, use of such a bypass capacitor allows for purifying the direct current received by the rotor excitation unit 122 and consequently allows for purifying the alternating current that is to be coupled to the resonant inductive power coupling arrangement 306.

In an embodiment, the rechargeable battery arrangement 106 may comprise Lithium Iron Phosphate (LiFeP04) gel polymer cells.

In an embodiment, the rotor 302 includes a rectifier arrangement 310 for converting resonant inductively coupled power received wirelessly at the rotor 302 into direct current (DC) to generate the rotor magnetic field. Specifically, the resonant inductive power coupling arrangement 306 is operable to transfer alternating current (AC) to the rotor 302. Subsequently, the rectifier arrangement 310 is operable to convert the transferred alternating current (AC) to direct current (DC). In an example, the rectifier arrangement 306 may be a bridge rectifier, for example a silicon bridge rectifier. Furthermore, the rectifier arrangement 310 may provide the converted direct current (DC) to the winding coils C (i.e. the rotor coil arrangement 216A-B, shown in FIG. 2), disposed on one or more planar rotor elements (such as the one or more plate-like rotor elements 208A-B of FIG. 2) of the rotor 302. Consequently, the converted direct current may generate a magnetic field of the rotor 302.

According to an embodiment, the winding coils C are formed at an angle of 60° and moreover, the winding coils C are disposed at a sector angle of 180° on the plate-like rotor elements. In one example, the winding coils C are disposed at a sector angle of 90° on the plate-like rotor elements. In another example, each of the winding coils C is associated with multiple turns of conductive tracks thereon.

In an embodiment, the switching control unit 124 includes a first switching arrangement 320 that is operable to switch commutation magnetizing currents supplied to the stator coil arrangement, such as stator coil arrangements 214A-B of FIG. 2, of the stator 304 when in operation. In one embodiment, the switching control unit 124 of the motor control arrangement is implemented with the help of the stator 304 by providing a silicon carbide transistor switching arrangement for switching commutation magnetizing currents supplied to the stator 304 when in operation. According to an embodiment, the stator 304, i.e. the one or more planar stator elements 204A-B of FIG. 2, is implemented as semi-circular half plates. Furthermore, each half-plate includes electrical winding coil arrangements, such as stator coil arrangements 214A-B of FIG. 2, implemented as phase coils Pl, P2 and P3. As shown, the phase coils Pl, P2 and P3 are disposed in a 3-phase arrangement and at a sector angle of 180° (such that each semi-circular half plates includes the phase coils Pl, P2 and P3 associated with the 3-phases). In one example, the phase coils Pl, P2 and P3 are disposed at a sector angle of 90°. In another example, each of the phase coils Pl, P2 and P3 are formed at an angle of 60°. In yet another example, each of the phase coils Pl, P2 and P3 is associated with multiple turns of conductive tracks thereon. As shown, the first switching arrangement 320 includes switching elements SI, S2, S3. Moreover, a negative connection of the rotor excitation unit 122 is coupled via the phase coils Pl, P2, P3 and their respective switches SI, S2, S3 to the negative terminal of the rechargeable battery arrangement 106. Although a three-phase commutation arrangement is described, it will be appreciated that other numbers of phases are optionally employed, for example five phases.

Optionally, the switching control unit 124 further includes a second switching arrangement 322, having switching elements S4, operable for selectively energizing a regenerative braking coil arrangement, such as the regenerative braking coil arrangement 218A, 218B, implemented as phase coils P4 when regenerative braking is applied in operation, which will be explained in greater detail herein later.

In an embodiment, digital commutation is provided to generate motion in the electrical motor of the regenerative braking arrangement 102. Furthermore, digital commutation may be implemented using digitally controlled current pulses. Optionally, the rotor magnetic field is operable to interact in operation with a commutated magnetic field of a stator 304 of the electrical motor. More optionally, during commutation, the current pulses are applied to commutation windings of the electrical motor, and a free-wheeling period is implemented between application of the current pulses during which the commutation windings are non-energized. Specifically, commutation winding of the at electrical motor may comprise electrical winding coil arrangement 214A-B of FIG. 2 disposed on the one or more planar stator elements 204A-B of the stator 304 (such as the stator 204 of FIG. 2). Therefore, current pulses may be applied to the phase coils Pl, P2, P3 using the first switching arrangement 320; specifically, switching elements SI, S2, S3 respectively. In operation, a current pulse may be provided to the phase coil Pl of the commutation winding using the switching element SI to generate a motion in the rotor 302. Subsequently, the current pulse may be switched to phase coil P2 of commutation winding using the switching element S2 to sustain the generated motion. Furthermore, the current pulses may be switched continuously from phase coil Pl to P2, P2 to P3 and subsequently, P3 to Pl to maintain rotational motion of the electrical motor 110 of FIG. 1. Specifically, the phase coils Pl, P2 and P3 are beneficially energized in sequence as the rotor 302 rotates, and the coils Pl, P2 and P3 are not energized simultaneously, namely only one commutated phase is energized at any given time. Therefore, a free-wheeling period may be implemented between the switching of current between the phase coils. Alternatively, optionally, for obtaining a smoother torque, two adjacent phase coils, for example the phase coils Pl and P2, are momentary simultaneous energized when the winding coils C straggle significantly both phases Pl and P2, and so forth.

Optionally, during commutation, current pulses are applied to the commutation windings of the electrical motor using pulse-width modulation (PWM). Specifically, width of the current pulses in a currenttime graph may be modulated to control speed of the electrical motor and operation of the switching control unit 124. Furthermore, by using pulse-width modulation power control, rotation rate and/or torque characteristics of the electrical motor can be controlled very precisely, enabling the electrical vehicle to exhibit extremely smooth and versatile power transmission to wheels thereof.

In operation, the switching control unit 124 is operable to selectively couple the regenerative braking coil arrangement, i.e. implemented as phase coils P4, for generating electrical power from the electrical motor when regenerative braking is applied in operation to recharge the rechargeable battery arrangement 106 of the electrical vehicle. Specifically, the motor control arrangement detects when regenerative braking is applied in operation, for example, with the help of a sensing element such as potentiometer. The application of the regenerative braking allows the rotor 302 to remain energized, i.e. continue to draw electrical power from the rechargeable battery arrangement 106, to generate a magnetic field. However, during regenerative braking, phase winding Pl, P2 and P3 are not energized by their respective switching elements SI, S2, S3, and the rotor excitation unit 122 is coupled directly across the rechargeable battery arrangement 106. Furthermore, during regenerative braking, the switching elements S4 (which may be implemented as a bypass silicon carbide transistor) is activated to cause the winding coils C of the rotor 302 to be energized, to generate power in the regenerative braking coil arrangement, i.e. implemented as phase coils P4, of the stator 304. For example, during the regenerative braking, the rotor 302 remains energized, which causes the winding coils C of the rotor 302 to generate a rotating magnetic field around the regenerative braking coil arrangement, i.e. the phase coils P4. This in turn causes induced power to be generated on the phase coils P4, which can subsequently be rectified (using rectifiers, not shown) for use in recharging the rechargeable battery arrangement 106. In an example, this may be achieved using an isolating switched inverter charging circuit.

The regenerative braking system of the present disclosure provides many benefits and enables harvesting of kinetic energy of a vehicle (for example, an electrical vehicle) that may be wasted during braking thereof. The regenerative braking system of the present disclosure improves energy efficiency of the electrical vehicle. Therefore, mileage per unit electrical power consumed by the electrical vehicle is increased. Furthermore, the regenerative braking system provides an eco-friendly system of recharging the battery vehicle by harvesting the energy that may have been dissipated as heat losses. Furthermore, the electrical motor of the regenerative arrangement employs magnetic bearings for operation; there is thereby reduced wear-and-tear in the electrical motor, thereby providing the electrical motor with an exceptionally longer operating lifetime (for example, many decades of times). Beneficially, a complexity of the regenerative braking system may be significantly reduced. Additionally, energy losses during transmission of electrical power to the battery of the electrical vehicle are substantially eliminated. For example, the rotor of the electrical motor, of the regenerative braking system of the present disclosure, does not require to be rotated in an opposite direction to act as a generator for regenerative braking. Essentially, with the rotation of the rotor of the electrical motor in a same direction allow the electrical motor of the regenerative braking system to act as the generator.

Modifications to embodiments of the invention described in the foregoing are possible without departing from the scope of the invention as defined 5 by the accompanying claims. Expressions such as including, comprising, incorporating, consisting of, have, is used to describe and claim the present invention are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the 10 singular is also to be construed to relate to the plural. Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.

Claims

1. A regenerative braking arrangement for an electrical vehicle, characterized in that the regenerative braking arrangement includes:

(i) at least one electrical motor including

- a casing,

- a rotor including

- one or more planar rotor elements attached to the shaft,

- magnetic bearings coupled to ends of the shaft of the rotor;

(ii) a motor control arrangement including

- a switching control unit for selectively coupling the regenerative braking coil arrangement for generating electrical power from the at least one electrical motor when regenerative braking is applied in operation to recharge the rechargeable battery arrangement of the electrical vehicle.

2. A regenerative braking arrangement of claim 1, characterized in that the electrical winding coil arrangements further comprises

- a stator coil arrangement arranged on the one or more planar stator elements, and

- a rotor coil arrangement arranged on the one or more planar rotor elements.

3. A regenerative braking arrangement of claim 2, characterized in that the regenerative braking coil arrangement is arranged on the one or more planar stator elements, wherein the regenerative braking coil arrangement is arranged on a first side of the one or more planar stator elements and the stator coil arrangement is arranged on a second side, opposite to the first side, of the one or more planar stator elements.

4. A regenerative braking arrangement of claim 2, characterized in that the switching control unit includes a first switching arrangement operable for switching commutation magnetizing currents supplied to the stator coil arrangement of the stator when in operation.

5. A regenerative braking arrangement of claim 4, characterized in that the switching control unit further includes a second switching arrangement operable for selectively energizing the regenerative braking coil arrangement when regenerative braking is applied in operation.

6. A regenerative braking arrangement of any one of the preceding claims, characterized in that the electrical winding coil arrangements are implemented using printed circuit board conductive tracks.

7. A regenerative braking arrangement of any one of the preceding claims, characterized in that the at least one electrical motor is operable to function as a digitally-commutated electrical motor, wherein, during commutation, current pulses are applied to commutation windings of the at least electrical motor, and a free-wheeling period is implemented between the current pulses during which the commutation windings are non-energized.

8. A regenerative braking arrangement of any one of the preceding claims, characterized in that the at least one electrical motor includes non-permanent-magnet ferrite elements for defining a torque-generating magnetic field for the at least one electrical motor when in operation.

9. A regenerative braking arrangement of any one of the preceding claims, characterized in that the rotor includes a rectifier arrangement for converting resonant inductively coupled power received at the rotor into a direct current to generate the rotor magnetic field.

10. A regenerative braking arrangement of claim 1, characterized in that the rotor is operable to rotate at a maximum rotation rate in a range of 30000 rotations per minute (r.p.m.) to 100000 rotations per minute (r.p.m.).

11. A regenerative braking arrangement of any one of the preceding claims, characterized in that the ends of the shaft of the rotor of the at least one electrical motor is further supported on permanent-magnetic magnetic bearings.

12. A regenerative braking arrangement of claim 11, characterized in that the ends of the shaft of the rotor of the at least one electrical motor is provided with a mechanical bearing that bears the shaft of the rotor relative to the stator when the magnetic bearing is loaded to cause at least a portion of a gap of the magnetic bearing to be mechanically contacted.

13. A regenerative braking arrangement of any one of the preceding claims, characterized in that the magnetic separation gap (G) is in a range of 0.5 mm to 5.0 mm.

14. A regenerative braking arrangement of any one of the preceding claims, characterized in that one or more planar rotor elements include a peripheral edge reinforcement arrangement for converting radial forces acting upon the rotor when rotating in operation into corresponding circumferential forces.

15. A method of using a regenerative braking arrangement for an electrical vehicle, characterized in that the method includes arranging for:

(i) at least one electrical motor to include

- a casing,

- a rotor including

- one or more planar rotor elements attached to the shaft,

- magnetic bearings coupled to ends of the shaft of the rotor;

(ii) a motor control arrangement including

- a switching control unit for selectively coupling the regenerative braking coil arrangement for generating electrical power from the at least one electrical motor when regenerative braking is applied in operation to recharge the rechargeable battery arrangement of 5 the electrical vehicle.