Description:Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompanying drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation. The numerical values mentioned in embodiment are only approximation, the values higher and/or lower than values mentioned fall within the scope of disclosures.
According to present invention, electric vehicle induction motor consists, of a circular stator lamination (100) and rotor lamination (200) separated by an air gap length (300). To simplify the understanding, stator winding from stator lamination (100) is omitted. Other components including but not limited to rotor end rings, shaft, enclosure, end covers, mechanical assembly, electrical insulation system, sensors and cooling assembly are the integral part of induction motor operation. Present embodiment can vary including but not limited to change in radial air gap length (300) and axial stack length (400). Plurality of stator lamination (100) and rotor lamination (200) of specific thickness and material class are axially bundled to get particular stack length (400) as per motor output requirement.
Said stator lamination (100) concentrically position between stator inner diameter (101) and stator outer diameter (102), consists of plurality of stator slot (103), plurality of stator tooth (104), a stator yoke (105) and plurality of cleating notch (106).
Plurality of stator slot (103) and stator tooth (104) are equally spaced and radially expanded from stator inner diameter (101) to stator outer diameter (102). Stator slot (103) of present embodiment are determined considering number of phase and number of pole pair and may vary to keep balance between stator tooth (104) flux density and manufacturability based on stator inner diameter (101) and stator outer diameter (102). Two adjacent sides of plurality of each stator slot (103) are arranged to form parallel sided stator tooth (104). A stator yoke (105) and plurality of stator tooth (104) are continuous part of assemble providing path to time varying flux.
Parallel sided stator tooth (104) of embodiment, shapes stator slot (103) such that stator slot (103) region near to stator yoke (105) referred as slot outer surface (103a)is broader than stator slot (103) region near to stator inner diameter (101) referred as slot inner surface (103b). The slot outer surface (103a) of each stator slot (103) is flat and the corners that joins slot outer surface (103a) to slot side surface (103c) have small slot corner radius (103d). Stator winding coils (not shown) are inserted inside each stator slot (103) through small stator slot opening (103e) made at stator inner diameter (101) periphery and remains inside the stator slot (103) due to slot lip (103f) and slot wedge (103g) section connected to slot inner surface (103b).
Larger stator outer diameter (102) than axial stack length (400) of present invention, maximizes the amount of torque per stator current and torque per rotor volume, furthermore radially expanded stator lamination (100) provides large slot area for stator winding and reduced axial stack length (400) shortens stator winding mean turn length successively results in small stator winding resistance, less winding cooper loss, improved efficiency and low temperature rise.
Ratio of stator outer diameter (102) to axial stack length (400) of embodiment varies between 1.2:1 and 3.0:1 as per motor output demand.
Ratio of stator outer diameter (102) to stator inner diameter (101) between 1.40:1 and 1.45:1 contributes to develop maximum torque-speed and power-speed demand of present electric vehicle induction motor.
Ratio of stator tooth height (104b)to stator yoke depth (105a) is optimized to 2.0:1 to minimalize magnetic saturation in stator yoke (105) and stator tooth (104).
Considering flux density limit and manufacturability, the ratio of stator tooth height (104b) to stator tooth width (104a) is optimized to 4.2:1.
Ratio of stator slot opening (103e) to slot lip (103f) between 2.2:1 and 3.2:1 is preferred as per stator winding manufacturing method.
Said rotor lamination (200) concentrically position between rotor inner diameter (201) and rotor outer diameter (202), consists of plurality of rotor slot (203), plurality of rotor tooth (204), a rotor yoke (205) and plurality of rotor duct (206).
Plurality of rotor slot (203) and rotor tooth (204) are equally spaced and radially expanded from rotor outer diameter (202) to rotor inner diameter (201). Rotor slot (203) of present embodiment are determined considering torque ripple and overall good performance and may vary to keep balance between rotor tooth (204) flux density and manufacturability based on rotor outer diameter (202) and rotor inner diameter (201). Two adjacent sides of plurality of each rotor slot (203) are arranged to form parallel sided rotor tooth (204). A rotor yoke (205) and plurality of rotor tooth (204) are continuous part of assemble providing path to time varying flux.
Parallel sided rotor tooth (204) of embodiment, shapes rotor slot (203) such that rotor slot (203) region near to rotor yoke (205) referred as slot inner surface (203a) is narrower than rotor slot (203) region near to rotor outer diameter (202) referred as slot outer surface (203b). The slot inner surface (203a) and slot outer surface (203b) of each rotor slot (203) are curved and the corners that joins slot inner surface (203a) and slot outer surface (203b) to slot side surface (203c) have small slot corner radius (203d). A small bridge thickness (203e) separates, completely closed plurality of rotor slot (203) from rotor outer diameter (202). Plurality of rotor bar (207) housed inside plurality of rotor slot (203) are short-circuited by end rings (208) on both sides.
Smaller rotor tooth height (204b) than rotor yoke depth (205a) of present invention reduces the volume of active part of rotor bar (207), furthermore single cage, shorter rotor slot (203) optimizes the torque-speed and power-speed requirement at low slip successively results in lower slip frequency, small rotor resistance, less copper loss in rotor bar (207), improved efficiency and low temperature rise. Additionally, shorter rotor slot (203) creates more space for rotor duct (206) inside rotor yoke (205).
Ratio of rotor tooth height (204b) to rotor yoke depth (205a) is optimized to 0.6:1.
Considering flux density limit and manufacturability, the ratio of rotor tooth height (204b) to rotor tooth width (204a) is optimized to a value 4.2:1.
Ratio of rotor slot bridge thickness (203e) to air gap length (300) of embodiment varies between 1.0:1 and 2.0:1 bearing in mind air gap length (300) varies between 0.4 and 0.8 millimeter.
Rotor bars (207) are either skewed by 8° mechanical angle to eliminate 11th order harmonic or 13° mechanical angle to eliminate 7th order harmonic or 18° mechanical angle to eliminate 5th order harmonic or between any of said mechanical angle to get overall good performance.
Plurality of rotor bar (207) housed in plurality of rotor slot (203) are made of either aluminum or aluminum alloy or copper or copper alloys based on electrical vehicle torque-speed and power- speed requirement. , C , C , C , Claims:We Claims,
1.Electric vehicle induction motor of present embodiment mainly consists of a circular stator lamination (100) and rotor lamination (200)
a. wherein stator lamination (100) consists of plurality of stator slot (103) and stator tooth (104) equally spaced and radially expanded from stator inner diameter (101) to stator outer diameter (102), a stator yoke (105) and plurality of cleating notch (106)
i. wherein stator slot (103) region near to stator yoke (105) referred as slot outer surface (103a) is broader than stator slot (103) region near to stator inner diameter (101) referred as slot inner surface (103b)
ia) wherein slot outer surface (103a) of each stator slot (103) is flat and the corners that joins slot outer surface (103a) to slot side surface (103c) have small slot corner radius (103d)
ib) wherein small stator slot opening (103e) is made at stator inner diameter (101) periphery
ic) wherein slot lip (103f) section connects slot wedge (103g) section and slot inner surface (103b)
ii. wherein two adjacent sides of plurality of each stator slot (103) forms parallel sided stator tooth (104)
ia) wherein plurality of stator tooth (104) have stator tooth width (104a) and stator tooth height (104b)
iii. wherein stator yoke (105) and plurality of stator tooth (104) are continuous assembly
ia) wherein stator yoke (105) have stator yoke depth (105a)
iv. wherein plurality of cleating notch (106) are equally spaced and positioned at stator outer diameter (102) periphery
b. wherein concentrically positioned rotor lamination (200) consists of plurality of rotor slot (203) and rotor tooth (204) equally spaced and radially expanded from rotor outer diameter (202) to rotor inner diameter (201), a rotor yoke (205) and plurality of rotor duct (206)
i. wherein rotor slot (203) region near to rotor yoke (205) referred as slot inner surface (203a) is narrower than rotor slot (203) region near to rotor outer diameter (202) referred as slot outer surface (203b)
ia) wherein slot inner surface (203a) and slot outer surface (203b) of each rotor slot (203) are curved and the corners that joins slot inner surface (203a) and slot outer surface (203b) to slot side surface (203c) have small slot corner radius (203d)
ib) wherein a small bridge thickness (203e) separates completely closed plurality of rotor slot (203) from rotor outer diameter (202) periphery wherein plurality of rotor bar (207) housed inside plurality of rotor slot (203) are short-circuited by end rings (208) on both sides
ii. wherein two adjacent sides of plurality of each rotor slot (203) forms parallel sided rotor tooth (204)
ia) wherein plurality of rotor tooth (204) have rotor tooth width (204a) and rotor tooth height (204b)
iii. wherein rotor yoke (205) and plurality of rotor tooth (204) are continuous assembly
ia) wherein rotor yoke (205) have rotor yoke depth (205a)
iv. wherein plurality of rotor duct (206) are equally spaced and positioned inside rotor yoke (205)
c. wherein circular stator lamination (100) and rotor lamination (200) are separated by an air gap length (300)
d. wherein plurality of stator lamination (100) and rotor lamination (200) of specific thickness and material class are axially bundled to get particular stack length (400)
2.Electric vehicle induction motor as claimed in claim 1, wherein said stator lamination (100) comprises 48 stator slot (103) and rotor lamination (200) comprises 44 rotor slot (203);
3.Electric vehicle induction motor as claimed in claim 1, wherein said stator lamination (100) dimensions such as stator inner diameter (101), stator outer diameter (102), stator tooth width (104a), stator tooth height (104b), stator yoke depth (105a), stack length (400), stator slot opening (103e), slot lip (103f) holds a numerical values
a. wherein ratio of stator outer diameter (102) to axial stack length (400) is between 1.2:1 and 3.0:1
b. wherein ratio of stator outer diameter (102) to stator inner diameter (101) is between 1.40:1 and 1.45:1
c. wherein ratio of stator tooth height (104b) to stator yoke depth (105a) is at least 2.0:1
d. wherein ratio of stator tooth height (104b) to stator tooth width (104a) is 4.2:1
e. wherein ratio of stator slot opening (103e) to slot lip (103f) is between 2.2:1 and 3.2:1
4.Electric vehicle induction motor as claimed in claim 1, wherein said rotor lamination (200) dimensions such bridge thickness (203e), rotor tooth width (204a), rotor tooth height (204b), rotor yoke depth (205a) holds a numerical values
a. wherein ratio of rotor tooth height (204b) to rotor yoke depth (205a) is 0.6:1
b. wherein ratio of rotor tooth height (204b) to rotor tooth width (204a) is 4.2:1
c. wherein ratio of rotor slot bridge thickness (203e) to air gap length (300) is between 1.0:1 and 2.0:1 bearing in mind air gap length (300) varies between 0.4 and 0.8 millimeter
5.Electric vehicle induction motor as claimed in claim 1, wherein said plurality of rotor bar (207) are skewed by either
8° mechanical angle to eliminate 11th order harmonic
13° mechanical angle to eliminate 7th order harmonic
18° mechanical angle to eliminate 5th order harmonic
between any of said mechanical angle for overall good performance;

6. Electric vehicle induction motor as claimed in claim 1, wherein said plurality of rotor bar (207) are made of either aluminum or aluminum alloy or copper or copper alloys.