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Title:
A MOTOR CUM GENERATOR
Document Type and Number:
WIPO Patent Application WO/2011/033520
Kind Code:
A2
Abstract:
The present invention relates to a motor cum generator. In particular the present invention relates to a motor cum generator that is capable of being coupled with a power assisting system that is capable of being integrated with vehicle / engine driven system so as to operate the same on electric and / or the original vehicle power source mode. The judicious combination of improved stator and modular winding of the motor cum generator of present invention provides capability to adapt on vehicle / engine driven system so as to operate at low voltage and high current conditions with enhanced power to frame size ratio thereby catering to the torque demand of varying capacity of engines with frame size of the motor cum generator that corresponds to the torque requirement of lowest capacity engine.

Inventors:
KSHATRIYA TEJAS KRISHNA (IN)
Application Number:
PCT/IN2009/000655
Publication Date:
March 24, 2011
Filing Date:
November 19, 2009
Export Citation:
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Assignee:
KPIT CUMMINS INFOSYSTEMS LTD (IN)
KSHATRIYA TEJAS KRISHNA (IN)
International Classes:
H02K29/00; B60L50/10
Domestic Patent References:
WO2008007120A22008-01-17
Foreign References:
EP1283583A22003-02-12
US20080116759A12008-05-22
Attorney, Agent or Firm:
GANGULI, Prabuddha (Plot N°262Sher-e-Punjab,Andheri East, Mumbai 3, IN)
Download PDF:
Claims:
CLAIMS

A motor cum generator comprising stator assembly, modular stator winding, rotor wherein stator assembly comprises of plurality of stampings wherein

the said stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

one or plurality of conductors are housed in each of the said slots and are insulated from the said stamping walls and base by insulating means,

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound wherein in the event of use of plurality of conductors, starting terminals of all the conductors inserted in the said passage are shorted and end terminals of the wound corresponding conductors are shorted

wherein

the said modular winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation of corresponding winding segment,

temperature sensing means disposed in the said winding;

wherein

rotor mounted on a shaft is disposed to maintain air gap between the inner diameter of the said stampings and outer diameter of the said rotor

wherein

selective excitation of the segment of the said stator winding by operating the said tapings and disposition of plurality of conductors in the said slots extended in the stamping enables the said motor cum generator operation for higher power outputs or at tailored current, voltage ratings and desired speed rating without changing stamping dimensions.

2. A motor cum generator as claimed in claim 1 wherein the ratio of outer diameter to inner diameter of the said stamping is in the range of 1.28 to 1.38.

3. A motor cum generator as claimed in claim 1 wherein the said slot of the said stator stamping is rectangle, trapezoid, triangular, square form.

4. A motor cum generator as claimed in claims 1 , 2 wherein the ratio of the depth to width of the said slot is in the range of 0.5 to 3.5. 5. A motor cum generator as claimed in claims 1-4 wherein the pitch of the slots is in the range of 5 to 25 mm.

6. A motor cum generator as claimed in claims 1-5 wherein the ratio of the staid stator stamping outer diameter to the slot depth is in the range of 1 to 12.

7. A motor cum generator as claimed in claims 1-6 wherein the shaft position encoding means is provided wherein two pulses are generated to sense shaft rotation direction and rotational speed. 8. A motor cum generator as claimed in claims 1-7 wherein the air gap between the inner diameter of the said stator stampings and outer diameter of the rotor is in the range of 0.5 to 1 mm.

9. A motor cum generator as claimed in claims 1- 8 wherein one or plurality of conductors are housed in each slot of the said stator stamping assembly.

10. A motor cum generator as claimed in claims 1-9 wherein one or plurality of temperature sensing means is disposed in the stator windings. 11. A motor cum generator as claimed in claims 1-10 wherein the said stator winding is configured in star connection.

12. A motor cum generator as claimed in claims 1-11 wherein the stator material is selected from silicon grade material M19, M36, cold rolled steel or combination thereof.

13. A motor cum generator as claimed in claims 1-12 wherein the said temperature sensing means is selected from thermocouple or RTD.

14. A motor cum generator as claimed in claims 1-13 wherein the said temperature sensing means is mounted on stator winding. 15. A motor cum generator as claimed in claims 1-14 wherein the stator and rotor winding is selected from copper, aluminum.

16. A motor cum generator as claimed in claims 1-15 wherein the fill factor of the said stator is in the range of 30% to 90%.

17. A motor cum generator as claimed in claims 1-16 comprising

stator assembly, modular stator winding, rotor

wherein stator assembly comprises of plurality of stampings wherein

the said stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls; - wherein

one or plurality of conductors are housed in each of the said slots and are insulated from the said stamping walls and base by insulating means,

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound wherein in the event of use of plurality of conductors, starting terminals of all the conductors inserted in the said passage are shorted and end terminals of the wound corresponding conductors are shorted

wherein

the said modular winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation of corresponding winding segment,

temperature sensing means disposed in the said winding; wherein

rotor mounted on a shaft is disposed to maintain air gap between the inner diameter of the said stampings and outer diameter of the said rotor

wherein

selective excitation of the segment of the said stator winding by operating the said tapings and disposition of plurality of conductors in the said slots extended in the stamping enables the said motor cum generator operation for higher power outputs or at tailored current, voltage ratings and desired speed rating without changing stamping dimensions

adapted on engine of vehicle for power assisting.

18. A motor cum generator as claimed in claim 1 wherein the said segments are configured in series or parallel connections with the aid of said tapings.

19. A motor cum generator wherein stator winding comprises of modular winding wherein winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation of corresponding winding segment.

20. A motor cum generator wherein stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

the ratio of outer diameter to inner diameter of the said stamping is in the range of 1.28 to 1.38, ratio of the depth to width of the said slot is in the range of 0.5 to 3.5, pitch of the slots is in the range of 5 to 25 mm.

21. A motor cum generator wherein the stator comprises of

stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side wails

wherein

the ratio of outer diameter to inner diameter of the said stamping is in the range of 1.28 to 1.38, ratio of the depth to width of the said slot is in the range of 0.5 to 3.5, pitch of the slots is in the range of 5 to 25 mm

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound.

A motor cum generator as claimed in claim 1 operates to provide power assistance to the engine of the vehicle in steps of:

matching torque characteristics of the said motor cum generator with the engine torque characteristics;

selectively exciting part of the said modular stator windings to match the torque characteristics;

supplying tailored current / voltage to the said modular winding. for the designed power output / speed / torque of the motor cum generator.

A motor cum generator as claimed in claims 1 , 22 is interfaced / adapted with controller of the vehicle on which it is to be adapted in steps of :

selectively exciting part of the said modular stator windings according to controller voltage / current rating;

supplying tailored current / voltage to the said modular winding

to enable selection of the controller of relatively lower voltage / current rating for the desired power output.

A motor cum generator as claimed in claims 1-16 comprising

stator assembly, modular stator winding, rotor

wherein stator assembly comprises of plurality of stampings wherein

the said stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

one or plurality of conductors are housed in each of the said slots and are insulated from the said stamping walls and base by insulating means,

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound wherein in the event of use of plurality of conductors, starting terminals of all the conductors inserted in the said passage are shorted and end terminals of the wound corresponding conductors are shorted wherein

the said modular winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation of corresponding winding segment,

temperature sensing means disposed in the said winding;

wherein

rotor mounted on a shaft is disposed to maintain air gap between the inner diameter of the said stampings and outer diameter of the said rotor

wherein

selective excitation of the segment of the said stator winding by operating the said tapings and disposition of plurality of conductors in the said slots extended in the stamping enables the said motor cum generator operation for higher power outputs or at tailored current, voltage ratings and desired speed rating without changing stamping dimensions

adapted on engine for power assisting.

25. A motor cum generator as claimed in claim 1 comprising

stator assembly, modular stator winding, rotor

wherein stator assembly comprises of plurality of stampings wherein the said stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

one or plurality of conductors are housed in each of the said slots and are insulated from the said stamping walls and base by insulating means,

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound wherein in the event of use of plurality of conductors, starting terminals of all the conductors inserted in the said passage are shorted and end terminals of the wound corresponding conductors are shorted wherein

the said modular winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation of corresponding winding segment,

temperature sensing means disposed in the said winding;

wherein

rotor mounted on a shaft is disposed to maintain air gap between the inner diameter of the said stampings and outer diameter of the said rotor

wherein

selective excitation of the segment of the said stator winding by operating the said tapings and disposition of plurality of conductors in the said slots extended in the stamping enables the said motor cum generator operation for higher power outputs or at tailored current, voltage ratings and desired speed rating without changing stamping dimensions

adapted on engine driven system for power assisting.

Description:
" A motor cum Generator"

Field of the Invention

The present invention relates to a motor cum generator. In particular the present invention relates to a motor cum generator that is capable of being coupled with a power assisting system that is capable of being integrated with vehicle / engine driven system so as to operate the same on electric and / or the original vehicle power source mode.

Background Art

Most of the engines and engine driven systems such as vehicles / cars are designed for peak power requirement. It is required to provide intermittent selective power assistance to these systems so as to enhance efficiency of the engine. For example cars that use electric and engine power source are designed to overcome problem of engine sizing and enhance engine performance. A motor as a part of power assisting system is used as a source of electric energy in such vehicles. This motor is also required to operate as generator selectively in these applications to charge batteries. Thus the motor is used to assist engine as well as a source of current to charge battery.

However in most of the applications motor and engine are developed as one integrated unit. Very few attempts have been made to adapt electric systems to existing vehicles, as coupling the motor with the engine of the vehicle, disposition of the motor in the available space and very high current ratings that are required for dual source applications pose techno-economic challenges. Designing of motors for such purposes using available stators lead to bulky motors that cause problems of mounting in the available spaces in existing vehicles. The power demand of the motor varies according to the increased engine capacity of the vehicle to achieve higher torque. It would be desirable to provide one frame size of the motor that is capable of being adapted to a wide range of vehicle/ engine capacities. This has led to the development of motor integrated engines for vehicles that use dual power source, popularly known as hybrid vehicles. However, it requires dedicated motor integrated engines and tailored transmission systems. Attempts have been made to develop high power density motor cum generators for vehicles that use electric and/or internal combustion engine power.

European Patent Application EP 1283583 discloses stator with high slot-fill factor that improves slot fill percentage without increasing the complexity or cost of the manufacturing operation. A high slot-fill stator design is provided, which allows and enables higher generator efficiencies and output for a given package size. However, means of selective excitation of the stator windings to achieve desired output without changing stator stamping dimensions is not disclosed in this application. US Patent 6232681 discloses a powdered magnetic material stator core with plurality of embedded stator windings. The plurality of stator windings are used to increase current density. However, the limitation of this system lies in its inflexibility of its frame size and power ratings for its adaption on a wide range of vehicle/ engine capacities. Further, the patent does not disclose multiple stamping materials or combinations and selective excitation of the stator windings.

US Patent Application 20060012260 aims to attain high fill factor by inserting plurality of conductors in the stator having side walls. However the limitation is in its non-adaptability on motors in existing engines / vehicles. The patent does not disclose use of multiple stamping materials along with selective excitation to achieve desired output.

US Patent 5982068 discloses motors with high current density using multiple conductors in stator slots. This invention provides substantial number of conductor members in a stator slot with small number of annular windings. Conductor member in the slot are paired with other members in the slot. However this arrangement suffers from the limitation of being non- compact with regard to power to motor frame size ratio. Use of multiple stamping materials along with selective excitation to achieve desired output is not taught in this patent.

WO/2006/028861 discloses motor system having multiple torque constants. The motor has a plurality of winding combinations that may be switched in and out of the motor circuit. A torque controller selects the winding combination in response to motor speed to deliver torque efficiently to the load throughout the speed range. However, this motor needs a dedicated torque controller to respond dynamically to deliver torque which also becomes a limiting factor for its adaptability to a range of existing vehicles / engines. US 2003178896 discloses rotary electrical machines. It comprises of a stator assembly having a plurality of conductive windings spaced around an axis of rotation, a rotor which is adapted to rotate about the axis of rotation dependent upon the flow of current through the stator windings, and a plurality of switching assemblies provided at circumferentially spaced locations around the stator. Each switching assembly is electrically connected between an end of at least one of the windings and a power supply busbar ring assembly) comprising at least one conductor. Each of the switching assemblies is effective to selectively control supply of current to at least one of the windings. The need for a switching assembly constraints its adaptation on existing engines / vehicles.

US Patent 6255755 disclose a single phase three speed motor with shared windings. There are multiple separate winding, and they are shared in various combinations in three configurations of the motor. 4-pole, 6-pole and 8-pole, each with different speed & torque characteristics. The necessity of varying number of poles poses limitations on adapting the motor on vehicle / engine because it is difficult to match engine characteristics with the motor. US Patent 5821660 discloses a brushless direct current motor having adjustable motor characteristics. It comprises of multiple stator windings wherein some of the windings are isolated in some configurations, while all windings are used in another configuration. One of the cited patents in this patent discloses winding configuration that allows configuring the same windings in star or delta configurations. However, the mere use multiple windings without increasing motor power to frame size ratio does not enable motor to be adapted to a variety of engines / vehicles.

US Application 2008/0116759 discloses adaptive winding system and control method for electric machines. It discloses an adaptive winding configurations and control method for the electromagnetic poles of electric machines, including motors and generators to dynamically adjust their operating characteristics to maintain a constant rated power over a large operating speed range with high efficiency. These generators are also able to dynamically change their output voltage and current (thus charging speed) when charging batteries depending on the charged state of the battery, and on the expected duration of the input power.

Such a system is not suitable for use in power assisting systems to be adapted on vehicles.

US Patent 5867005 discloses AC motor winding circuit in which a method to connect two main and one auxiliary winding in series or parallel configurations to handle different voltage ratings is described. The use of auxiliary winding results in increased weight of the motor, which is undesirable.

US Patent 7075206 discloses alternator that provides lower output while using same stator core and winding by virtue of pairing of the conductors wherein first pair of conductors and second pair of conductors occupy adjacent slots in the stator. The selective excitation of the stator windings to achieve desired output without changing stator stamping dimensions along with multiple stamping materials is not disclosed / taught in this patent. US Patent 6278217 discloses coils that are stacked in a slot and sandwiched between separator bars also in the slot to achieve higher current density. The patent does not mention about selective excitation of the stator windings to achieve desired output without changing stator stamping dimensions along with multiple stamping materials.

US Patent 20060012259 discloses a ac induction motor with a flat form factor by virtue of the end of the wire being greater than the width of the stator. The patent also mentions of increasing the gap between the stator and rotor to increase motor torque. However the patent does not mention combinations of multiple stamping materials or unique dimensions of the stator slots along with selective excitation achieved by means of multiple windings.

WO/2006/028861 discloses an electric motor along with a torque controller that selects winding combinations in response to motor speed to deliver torque efficiently. However the patent does not mention use of multiple stamping materials along with unique combinations of ratios of dimensions for the stator slots.

US7061149 discloses an electric motor with stator having multiple conductive windings and switching assemblies connected electrically. The patents however does not unique combinations of ratios of dimensions for the stator slots along with combinations of multiple stamping materials

US6255755 mentions a single-phase, three speed induction motor comprising a stator, a rotor rotatably mounted in the stator having multiple slots and windings operating at different speeds. The patents however does not mention unique combinations of ratios of dimensions for the stator slots along with combinations of multiple stamping materials

US 20080 6759 mentions an adaptive winding configuration and control method for electric motors to dynamically adjust operating characteristics. However the patent does not mention unique combination of ratios of dimensions for the stator slots along with combinations of multiple stamping materials

US5867005 mentions an ac motor winding circuit for use with different input signals along with a switch connected to the main winding to switch between multiple configurations. However the patent does not mention unique combination of ratios of dimensions for the stator slots along with combinations of multiple stamping materials US6048219 mentions an electrical connector for configuring the supply voltage of rotary electric machines or motors having multiple windings. However the patent does not mention unique combination of ratios of dimensions for the stator slots along with combinations of multiple stamping materials

Attempts are made to develop DC motor for providing power assisting.

US Patent 6424798 discloses a sensoriess brushless-DC-motor mounted on an electric or hybrid vehicle is powered by an on-board battery through an inverter supplying a three-phase pulse width modulated voltage (PW voltage).

Japanese Patent JP2007143290 discloses a hybrid vehicle that is mounted with a second DC power supply device that generates power equivalent to power consumed by the auxiliary machine, besides a first DC power supply device that feeds DC power to a power converter that drives

Prior art reports use of electric motor cum generator on hybrid vehicles.

US Patent Application 20090029823 discloses a hybrid vehicle having at least one electric motor which is usable as a generator and charges a vehicle battery during a recuperation phase, there is provided an additional actuating element independent of a brake system which is used to transfer the electric motor into its recuperation state without activating the brake system. US Patent 4470476 discloses hybrid vehicles having two or more power plants which can be operated independently or simultaneously and includes an electric motor as well as an internal combustion engine which may be selectively connected to drive the drive wheels of such vehicles either independently or simultaneously. Conventional motor / power systems used for power assisting system suffer from following drawbacks:

Existing designs result in non-adaptable frame sizes especially with regard to motors for higher capacity engine in vehicles which have space limitations. Larger frame sizes lead to increase in weight per unit power output of motor. This adversely impacts on their adaptability to engines/ vehicles of varying capacities.

Non-adaptable motors for use in existing vehicles / engines specifically with regard to their matching / tuning torque characteristics. Operating a motor on low voltage and high current requires the use of thick conductors thereby resulting in larger frame sizes of motors.

There is a long felt need to provide motor cum generators for power assisting systems that are capable of being integrated with vehicle / engine driven system so as to operate at low voltage and high current conditions with enhanced power to frame size ratio thereby catering to

the torque demand of varying capacity of engines with frame size of the motor that corresponds to the torque / power requirement of lowest capacity engine,

spectrum of vehicles with varied capacity of engines yet maintaining lower weight of the motor cum generator.

Summary of the Invention

The main object of the invention is to provide a motor cum generator for low voltage and high current applications.

Another object of the invention is to provide a motor cum generator that is capable of being coupled with a power assisting systems. Another object of the invention is to provide a motor cum generator with enhanced power to frame size ratio.

Yet another object of the invention is to provide motor cum generator that is capable of providing power assistance to varied capacity of engines without increase in frame size with respect to capacity / power demand of the engine.

Another object of the invention is to provide improved stator stamping for the motor cum generator. Yet another object of the invention is to improve stator slots to house various types of windings according to torque requirement corresponding to engine capacity / vehicle capacity.

Yet another object of the invention is to provide modular winding for the motor cum generator. Yet another object of the invention is to provide temperature sensing means to monitor winding temperature of the motor cum generator. Yet another object of the invention is to provide motor rotational speed and direction sensing means to monitor the speed and direction of the motor cum generator.

Yet another object of the invention is to enhance forced air cooling of the motor cum generator to maximize the heat dissipation when using the motor at its peak capacity.

Yet another object of the invention is to provide adequate insulation between the motor windings and motor body to avoid any breakdown of insulation due to high temperature / currents / voltages.

Yet another object of the invention is to provide appropriate conductor size that is compatible with the available stators such as IEC, NEMA etc. for corresponding power ratings.

Yet another object of the invention is to enhance adaptability of motor for the power assisting system.

Yet another object of the invention is to provide three phase AC motor for the power assisting system used on vehicle. Yet another object of the invention is to provide a motor cum generator using stator available as per industry standard such as IEC, NEMA.

Another object of the invention is to provide motor cum generator for power assisting engine of vehicle.

Another object of the invention is to provide motor cum generator for engine.

Another object of the invention is to provide motor cum generator for engine driven system. Another object of the invention is to provide motor cum generator that offers flexibility to select lower voltage handling capacity controller when adapted on vehicle.

Thus in accordance with the invention, the motor cum generator comprising stator assembly, modular stator winding, rotor

wherein stator assembly comprises of plurality of stampings

wherein the said stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

one or plurality of conductors are housed in each of the said slots and are insulated from the said stamping walls and base by insulating means

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound wherein in the event of use of plurality of conductors, starting terminals of all the conductors inserted in the said passage are shorted and end terminals of the wound corresponding conductors are shorted

wherein

the said modular winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation , of corresponding winding segment,

temperature sensing means disposed in the said winding;

wherein

rotor mounted on a shaft is disposed to maintain air gap between the inner diameter of the said stampings and outer diameter of the said rotor

wherein

selective excitation of the segment of the said stator winding by operating the said tapings and disposition of plurality of conductors in the said slots extended in the stamping enables the said motor cum generator operation for higher power outputs or at tailored current, voltage ratings and desired speed rating without changing stamping dimensions.

In another aspect of the invention the motor cum generator comprises of a stator provided with circumferential slots, rotor, two or plurality of poles, output shaft, conductors that are wound on the said stator

wherein each of the stator slot houses a cluster of conductors wherein cross section of each conductor is such that it passes through the opening of the said slot. In another aspect of invention the said motor cum generator is adapted on engine of vehicle for power assisting. In yet another aspect of the invention the said motor cum generator is adapted on engine for power assisting.

In yet another aspect of the invention the said motor cum generator is adapted on engine driven system.

In another aspect of the invention stator winding comprises of modular winding wherein winding corresponding to each of the phase out of three phases is provided with intermediate one or plurality of tapings so as to enable excitation of corresponding winding segment. In another aspect of the invention the said motor cum generator operates to provide power assistance to the engine of the vehicle in steps of:

matching torque characteristics of the said motor cum generator with the engine torque characteristics;

selectively exciting part of the said modular stator windings to match the torque characteristics;

supplying tailored current / voltage to the said modular winding.

In another aspect of the invention the said stamping is in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

the ratio of outer diameter to inner diameter of the said stamping is in the range of 1.28 to 1.38, ratio of the depth to width of the said slot is in the range of 0.5 to 3.5, pitch of the slots is in the range of 5 to 25 mm.

In another aspect of the invention stator comprises of stamping in the form of a substantially circular lamina wherein the portion in the vicinity of the centre of the said lamina is cut so as to create annular region wherein inner edge portion of the said annular region is provided with plurality of circumferential slots

wherein

each of the slots comprises of open portion / opening region to insert conductors and base region to provide seat for the conductors, the slot extends into the said annular region and is bound by the two side walls;

wherein

the ratio of outer diameter to inner diameter of the said stamping is in the range of 1.28 to 1.38, ratio of the depth to width of the said slot is in the range of 0.5 to 3.5, pitch of the slots is in the range of 5 to 25 mm.

wherein

plurality of stampings are stacked on each other to form cylinder like structure wherein the stampings are disposed such that the said side walls and base of each of the slots of each stamping match with the other stamping such that a longitudinal passage is created for conductors to be wound.

Detailed Description of the Invention

Features and advantages of the invention will become apparent in the following detailed description and the preferred embodiments with reference to the accompanying drawings.

Figure 1 Representation of a single conductor section (Sheet 1)

Figure 2 .Exploded view of stator slot (Sheet 1)

Figure 3 Conductor connection representation (Sheet 1)

Figure 4 Schematic of a stamping (Sheet 2)

Figure 5 Schematic of stator (Sheet 2)

Figure 6 Winding configuration (Sheet 3)

Figure 7 Winding configuration (Sheet 3)

Figure 8 Segmented winding configuration (Sheet 4)

Figure 9 Series winding configuration (Sheet 5)

Figure 0 Parallel winding configuration (Sheet 6)

The motor cum generator of the present invention comprises of a stator provided with circumferential triangular slots, rotor, two or plurality of poles, output shaft, conductors that are wound on the said stator. Figures 1, 2 and 3 illustrate the inventive feature of the motor cum generator that is used in power assisting system for vehicle/ engine driven systems. The said power assisting system application demands motor to operate on low voltage and high current that can get to as high as 200 Amps. Typically, thick conductors are used to ensure high current carrying capacity. However, when conductor size increases, it is imperative to choose stator core with larger slots ensuring the ease of winding of thick conductors. Such larger stators cause severe limitations especially when motor sizes in applications become critical.

The stator used in the present invention is of stator size. Figure 1 depicts cross section of one of the conductors wherein it passes through the gap 10 of the slot in stator 20 as shown in Figure 2. It can be noted that the illustration of stator surface is made in the Figure 2. There is a plurality of slots 30 on the circumference of the stator. It is surprisingly found instead of using one conductor whose cross sectional dimensions and hence current carrying capacity is limited by the said gap 10, it is possible to use cluster of smaller diameter conductors in the same slot. This is illustrated in Figure 2 wherein plurality of smaller diameter conductors 50 is accommodated in the said slot 30. These conductors are then connected as shown in Figure 3 that shows each winding turn. Each turn ends with two terminals. In the first one it ends with A1 , B1. In the second turn it ends with A2 , B2 and so on. These terminals are then shorted in such a way that A1, A2, A3, up to An are shorted and B1, B2.B3 up to Bn are also shorted. Power is connected across the two end terminals. This arrangement can carry n times as much current as a single winding would.

Figure 4 illustrates schematic of a stamping 40 of the motor cum generator. The said stamping is in the form of a substantially circular lamina wherein the portion 43 in the vicinity of the centre of the said lamina is cut so as to create annular region 42 as indicated in the Figure 4. The inner edge portion 44 of the said annular region 42 is provided with plurality of circumferential slots 45. Each of the slots comprises of open portion / opening region 50 and base region 51. The slot extends into the said annular region 42 and is bound by the walls 52. The reference numerals are indicated only for one slot as a representation, it may be noted that all the slots comprise of the open region, base portion and the walls that bound the slot.

The said depth d2 (indicated by numeral 46) of the slot is the distance from the inner annular edge portion 44 to the base region 51 of the slot. The distance d1 (indicated by the numeral 55) is the width of the annular region; it is the distance between the inner edge portion 44 of the annular region 42 to the outer edge portion 56. The distance between the said base region 51 of the slot and the said outer edge portion 56 is shown as W (indicated by reference numeral 60) in Figure 4. Figure 5 depicts stator assembly 70. It comprises of plurality of stampings 40 stacked on each other to form cylinder like structure of length L which is the length of the stator. The stampings are disposed such that the slots, in particular walls of each of the slots of each stamping match with the other stamping such that a longitudinal passage created. The conductors are disposed in these passages. The outer diameter of the rotor is shown in Figure 5 and indicated by numeral 75.

The inner diameter of the rotor is indicated by the reference numeral 76. In one of the embodiments the ratio of outer to inner diameters is in the range of 1.28 to 1.38. The said outer diameter is the radial distance between opposite annular edge portions 44 of the said stamping. The conductors are disposed in the passages to complete winding of the stator wherein each turn of the winding corresponds to the length of the conductor that is laid in the said passages through distance L of the stator and again wound back from outside over the said outer region 56 of the stampings. This is indicated as representation by dashed line 80 in the Figure 5. It may be noted that these are only the directional representation of one of the embodiments to indicate how the conductors are wound. There is one or plurality of conductors in each slot and terminals of each of the conductor are shorted with each other. The terminals corresponding to three phases R, Y and B are taken out to be configured in star type.

Figure 6 and Figure 7 depict winding configuration of the stator. It can be noted from the Figure 7 that the winding configuration is primarily star type. In Figure 6, representation of the windings R, Y and B is indicated by numerals 90, 91 and 92 respectively. The respective terminals are indicated as R1-R4, Y1-Y4 and B1-B4.

The winding is modular type wherein each of the winding is provide with further winding tapings in the form of R2, R3, Y2, Y3, B2, B3. There could be plurality of tapings depending on the requirement and end application. It may be noted that the said tapings can be selectively excited by passing current to activate portion of the winding so as to achieve desired power / torque output. It is surprisingly found that the modular winding and increase in the slot depth d2 for the same outer diameter of the stator substantially enhances power to frame size ratio (frame size of the motor cum generator is primarily function of stator diameter and stator length). Thus it is possible to adapt the said motor cum generator of the same frame size for higher capacities.

The usefulness of the above construction is illustrated as follow:

Let us assume that a motor cum generator of 2.4 kW capacity motor with frame size X is required for a 0.8 litre capacity (swept volume) engine. The present construction allows the adaptation of the same X frame size motor cum generator for a vehicle using 1.3 litre engine that needs 10 kW capacity motor cum generator without increasing frame size of the motor cum generator.

It is therefore possible to deliver higher power rating from the motor cum generator with frame size corresponding to lowest power rating without changing stator, rotor etc. Thus power out put to frame size ratio is clearly enhanced.

The adaptation of the motor cum generator on vehicle / engine is possible with the use of the modular winding. The motor cum generator functions in a manner to provide flexibility in terms of voltage, current and speed. The said motor cum generator is operated on desired and tailored voltage and / or current for the same power rating by virtue of modular winding. For example using combination of said tapings, the motor cum generator can operate at 20 Volts and 10 Amp as well as 10 Volts 20 Amp. It therefore ought to be noted that though power output is same, the construction provides the flexibility of selecting the current and voltage ratings, an aspect distinctly lacking in any of the motors disclosed in the prior art.

The motor cum generator can function at desired speed as the rated speed. This is achieved by selecting the tapings of the modular winding. The motor cum generator can therefore be operated in a band of speeds thereby enhancing the torque response to a vehicle / engine to which it is adapted. The flexibility of operating the motor cum generator at desired rated speed enables coupling of the motor cum generator at the engine, just before gear box and after gear box wherein speed of the transmission shaft is different from that of the engine. This makes the motor cum generator robust, adaptable and responsive to the need of the vehicle / engine which is a distinct and major step as compared to any of the systems in the prior art.

The functioning of the motor cum generator in a modular fashion as mentioned above is elaborated with reference to Figure 8. In this representation for illustration and understanding it is presumed that the tapings from each of the winding as described in Figure 6 lead to segment of coil, for example coil segment between R1 to R2 is considered as A (indicated by reference numeral 94), coil segment between R2 and R3 is considered as B (indicated by reference numeral 95). With reference to Figure 8, let the voltage across winding A is v and current passing through it is / ' . Similarly the voltage across winding B is v and current passing through it is / ' . Power required is P and it is equal to w for each winding. For example, of current is 10 Amp and voltage is 10 Volt the power rating is 100 Watt.

The motor cum generator functions to work on desired / tailored voltage and current ratings. One of the embodiments is represented in Figure 9. The tapings and thereby segments of the said winding 94 and 95 are connected in series to form a combined series winding configuration 96. The voltage across winding A (94) and B (95) in series is 2v and current passing through it is / ' . Power required is 2P and it is equal to 2vi. Thus, continuing with the values of current and voltage from above example, the voltage in the winding becomes double to 20 Volt and current is 10 Amp by virtue of series connection of the said segments. Thus the power rating is 200 x 10 that is 200 Watt.

The motor cum generator functions to operate on increased power without increase in the voltage rating with configuration depicted in Figure 10. The coil segments A (94) and B (95) are connected in parallel wherein voltage across the said winding segments is v and current passing through it is increased to 2i. Thus power required is 2P and it is equal to 2vi. Continuing with the same ratings as mentioned above, the current rating is increased from 10 Amp to 20 Amp in the circuit yet the voltage is 20 Volt resulting in power of 200 Amp.

Thus with the same frame size motor it is possible to increase the output to double. It may be noted that this is a representative example and the current and voltage ratings are mentioned to explain the functioning. The functioning of the motor is not limited to these ratings.

The said motor cum generator is adapted on an engine / vehicle to provide power assisting. The said motor cum generator functions to provide necessary intermittent demanded torque in steps of:

matching torque characteristics of the said motor cum generator with the engine torque characteristics;

selectively exciting part of the stator windings to match the torque characteristics;

supplying desired / tailored current / voltage for the designed power output.

In one of the embodiments the stator stamping material is selected from silicon grade material M19 or M36, cold rolled steel or combination thereof.

In one of the embodiments the said stator stamping slots are in the form of rectangle, trapezoid, triangular, square or combination thereof.

In another embodiment the ratio of the said slot depth to width is in the range of 0.5 to 3.5.

In yet one of the embodiments the ratio of the staid stator stamping outer diameter to the slot depth is in the range of 1 to 12.

In yet one of the embodiment pitch of the slots is in the range of 5 to 25 mm. In yet another embodiment the shaft position encoding means is provided wherein two pulses are generated to sense shaft rotation direction and rotational speed.

In yet one of the embodiment air gap between the inner diameter of the said stator stampings and outer diameter of the rotor is in the range of 0.5 to 1 mm.

In yet one of the embodiment one or plurality of conductors are housed in each slot of the said stator stamping assembly.

In yet one of the embodiment one or plurality of temperature sensing means is disposed in the stator windings. In one of the variants of this embodiment the said temperature sensing means is selected from thermocouple and RTD.

In yet another embodiment the said winding is selected from copper, aluminum. In one of the embodiments the fill factor (ratio of cross section / volume available in the slot to the cross section / volume occupied by the conductors) of the said stator is in the range of 30% to 90%.

Thus it is evident that the splitting of a conductor into plurality of smaller size conductors that can pass through opening of the slot of the available stator, improvement in the stamping and modular winding results in providing a motor with enhanced power to frame size ratio for low voltage and high current operational conditions.