http://www.flyelectric.com/ans.kv.html
Inductance Decides kv
code to change the motor amp limit

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Re: code to change the motor amp limit
Last edited by Hummie on 24 May 2017, 17:51, edited 2 times in total.

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Re: code to change the motor amp limit
5 thin strands doing 10 turns each is the same inductance as 1 big strand doing the same 10 turns pretty much, as apposed to one thin strand doing 50 turns and greatly reduce the kv
Inductance decides kv and the resistance produced is an unfortunate byproduct. A correlation you find works in a specific motor design with specific parts but if you compare other motor designs (axial or transverse) or using different conductors (aluminum, multi strand, carbon), or maybe even different sizes, I think you will get a different ratio which I'd like to see. But even with the same parts it's possible to get greater or lesser inductance with the same conductance depending on how well the wires are wound. If you do a bad job winding and the turns are messy the inductance is not as much.
I think it's interesting info and valuable to a degree but it's not a causal relationship or one that reveals a relationship between conductance and inductance universally
Inductance decides kv and the resistance produced is an unfortunate byproduct. A correlation you find works in a specific motor design with specific parts but if you compare other motor designs (axial or transverse) or using different conductors (aluminum, multi strand, carbon), or maybe even different sizes, I think you will get a different ratio which I'd like to see. But even with the same parts it's possible to get greater or lesser inductance with the same conductance depending on how well the wires are wound. If you do a bad job winding and the turns are messy the inductance is not as much.
I think it's interesting info and valuable to a degree but it's not a causal relationship or one that reveals a relationship between conductance and inductance universally

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Re: code to change the motor amp limit
Motor:
Delta
100kv
50 turns
1 cross section
1 copper volume
0.08300 ohm resistance leadtolead (0.0415 ohm VESC detection)
12.04819 siemens conductance = 1/0.08300 ohm
KV Formula For Motor:
100kv = A x 1.73205[Delta] x 50
KV = 100
A = X = Constant(motor)
B = 1.73205 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 50 = turns
This formula can be rearranged to:
A = 1.15470
Therefore:
Formula For Test Motor:
100kv = 1.15470 [A] x 1.73205 [B  Delta] x 50 [C]
100 = 1.15470 x 1.73205 x 50
KV = 100
A = 1.15470 = Constant(motor)
B = 1.73205 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 50 = turns
^Simply 50 turns delta gives 100kv

Retermination of original Test Motor From 100kv Delta to 57.735kv Wye:
Wye
57.735kv = 100kv / sqrt(3) < less kv
50 turns < same turns
1 cross section < same cross section
1 copper volume < same copper volume
0.249 ohm resistance leadtolead = original 0.0830ohm x 3 (0.1245 ohm VESC detection) < 3 times more resistance
4.01606 siemens conductance = original 12.04819 siemens / 3 = 1 / 0.249 ohms < 1/3rd as much conductance
Formula For Retermination of original Test Motor From Delta to Wye:
57.735kv = 1.15470 [A] x 1 [B  Wye] x 50 [C]
57.735 = 1.15470 x 1 x 50
KV = 57.735
A = 1.15470 = Same Constant(motor) as Delta
B = 1 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 50 = turns
^Simply 50 turns wye gives 57.735kv

^So far matches my formula:
conductance change factor: 0.333...  12.04819 original siemens x 0.333... conductance change factor = 4.01606 new siemens
kv change factor: sqrt(0.33333) = 0.57735  100 original kv x sqrt(0.33333) kv change factor = 57.735 new kv

To be continued....
Delta
100kv
50 turns
1 cross section
1 copper volume
0.08300 ohm resistance leadtolead (0.0415 ohm VESC detection)
12.04819 siemens conductance = 1/0.08300 ohm
KV Formula For Motor:
100kv = A x 1.73205[Delta] x 50
KV = 100
A = X = Constant(motor)
B = 1.73205 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 50 = turns
This formula can be rearranged to:
A = 1.15470
Therefore:
Formula For Test Motor:
100kv = 1.15470 [A] x 1.73205 [B  Delta] x 50 [C]
100 = 1.15470 x 1.73205 x 50
KV = 100
A = 1.15470 = Constant(motor)
B = 1.73205 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 50 = turns
^Simply 50 turns delta gives 100kv

Retermination of original Test Motor From 100kv Delta to 57.735kv Wye:
Wye
57.735kv = 100kv / sqrt(3) < less kv
50 turns < same turns
1 cross section < same cross section
1 copper volume < same copper volume
0.249 ohm resistance leadtolead = original 0.0830ohm x 3 (0.1245 ohm VESC detection) < 3 times more resistance
4.01606 siemens conductance = original 12.04819 siemens / 3 = 1 / 0.249 ohms < 1/3rd as much conductance
Formula For Retermination of original Test Motor From Delta to Wye:
57.735kv = 1.15470 [A] x 1 [B  Wye] x 50 [C]
57.735 = 1.15470 x 1 x 50
KV = 57.735
A = 1.15470 = Same Constant(motor) as Delta
B = 1 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 50 = turns
^Simply 50 turns wye gives 57.735kv

^So far matches my formula:
conductance change factor: 0.333...  12.04819 original siemens x 0.333... conductance change factor = 4.01606 new siemens
kv change factor: sqrt(0.33333) = 0.57735  100 original kv x sqrt(0.33333) kv change factor = 57.735 new kv

To be continued....
Last edited by devin on 25 May 2017, 19:30, edited 6 times in total.

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Re: code to change the motor amp limit
ReWinding the 57.735 KV Wye to 100 KV Wye Keeping Same Copper Volume:
Wye
100kv = 57.735kv original wye x sqrt(3) [kv change factor sqrt(3)] < more kv
28.86 turns = 50 original turns / sqrt(3) < less turns
1.73205 cross section = 1 x sqrt(3) [keeps copper volume constant after turns reduction] < more cross section
1 copper volume < same copper volume
0.0830 ohm resistance leadtolead = original 0.249ohm / 3 (0.0415 ohm VESC detection) [resistance change factor 0.333...] < 1/3rd as much resistance
12.04819 siemens conductance = original 4.01606 siemens x [3 conductance change factor] = 1 / 0.0830 ohm < 3 times as much conductance
Formula For ReWinding the New 57.735 KV Wye to 100 KV Keeping Same Copper Volume:
100kv = X [A] x 1 [B  Wye] x 28.86 [C]
This formula can be rearranged to:
A = 3.46500 = ( 3 x 1.15470 original Constant(motor) # )
^notice motor constant change factor [3] from original value is equal to conductance change factor [3].
Therefore:
100kv = 3.46500 [A] x 1 [B  Wye] x 28.86 [C]
100 = 3.46500 x 1 x 28.86
100 = (3 x 1.15470 original Constant(motor) value) x 1 x 28.86
KV = 100
A = 3.46500 = (3 x 1.15470 original Constant(motor) value) = Constant(motor)
B = 1 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 28.86 = turns
^Simply 28.86 turns wye gives 100kv

^So far matches my formula:
conductance change factor: 3  4.01606 original siemens x 3 conductance change factor = 12.04819 new siemens
kv change factor: sqrt(3) = 1.73205  57.735 original kv x sqrt(3) kv change factor = 100 new kv
notice motor(constant) number has necessarily increased by the same factor [3] as the conductance change factor [3] for the equation to provide a valid answer

ReWinding the New 100 KV Wye to 150 KV Wye Keeping Same Copper Volume:
To be continued...
Wye
100kv = 57.735kv original wye x sqrt(3) [kv change factor sqrt(3)] < more kv
28.86 turns = 50 original turns / sqrt(3) < less turns
1.73205 cross section = 1 x sqrt(3) [keeps copper volume constant after turns reduction] < more cross section
1 copper volume < same copper volume
0.0830 ohm resistance leadtolead = original 0.249ohm / 3 (0.0415 ohm VESC detection) [resistance change factor 0.333...] < 1/3rd as much resistance
12.04819 siemens conductance = original 4.01606 siemens x [3 conductance change factor] = 1 / 0.0830 ohm < 3 times as much conductance
Formula For ReWinding the New 57.735 KV Wye to 100 KV Keeping Same Copper Volume:
100kv = X [A] x 1 [B  Wye] x 28.86 [C]
This formula can be rearranged to:
A = 3.46500 = ( 3 x 1.15470 original Constant(motor) # )
^notice motor constant change factor [3] from original value is equal to conductance change factor [3].
Therefore:
100kv = 3.46500 [A] x 1 [B  Wye] x 28.86 [C]
100 = 3.46500 x 1 x 28.86
100 = (3 x 1.15470 original Constant(motor) value) x 1 x 28.86
KV = 100
A = 3.46500 = (3 x 1.15470 original Constant(motor) value) = Constant(motor)
B = 1 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 28.86 = turns
^Simply 28.86 turns wye gives 100kv

^So far matches my formula:
conductance change factor: 3  4.01606 original siemens x 3 conductance change factor = 12.04819 new siemens
kv change factor: sqrt(3) = 1.73205  57.735 original kv x sqrt(3) kv change factor = 100 new kv
notice motor(constant) number has necessarily increased by the same factor [3] as the conductance change factor [3] for the equation to provide a valid answer

ReWinding the New 100 KV Wye to 150 KV Wye Keeping Same Copper Volume:
To be continued...

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Re: code to change the motor amp limit
ReWinding the 100 KV Wye to 150 KV Wye Keeping Same Copper Volume:
Wye
150kv = 100kv original wye x 1.5 [kv change factor 1.5] < more kv
19.24 turns = 28.86 original turns / 1.5 < less turns
2.59807 cross section = 1.73205 original cross section x 1.5 [keeps copper volume constant after turns reduction] < more cross section
1 copper volume < same copper volume
0.03688 ohm resistance leadtolead = (((original 0.0830 ohm)/1.5 [less turns])/1.5 [more cross section]) (0.01844 ohm VESC detection) [resistance change factor 0.44433...] < 0.44433 times as much resistance
27.11496 siemens conductance = original 12.04819 siemens x [2.25054 conductance change factor] = 1 / 0.03688 ohm < 2.25054 times as much conductance
Formula For ReWinding the 100 KV Wye to 150 KV Wye Keeping Same Copper Volume:
150kv = X [A] x 1 [B  Wye] x 19.24 [C]
This formula can be rearranged to:
A = 7.79625 = ( 2.25 x 3.46500 original Constant(motor) # )
^notice motor constant change factor [2.25] from original value is equal to conductance change factor [2.25054].
Therefore:
150kv = 7.79625 [A] x 1 [B  Wye] x 19.24 [C]
150 = 7.79625 x 1 x 19.24
150 = (2.25 x 3.46500 original Constant(motor) value) x 1 x 19.24
KV = 150
A = 7.79625 = (2.25 x 3.46500 original Constant(motor) value) = Constant(motor)
B = 1 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 19.24 = turns
^Simply 19.24 turns wye gives 150kv

^So far matches my formula:
conductance change factor: 2.25054  12.04819 original siemens x 2.25054 conductance change factor = 27.11496 new siemens
kv change factor: sqrt(2.25054) = 1.50017  100 original kv x 1.50017 kv change factor = 150.0 new kv
notice motor(constant) number has necessarily increased by the same factor [2.25] as the conductance change factor [2.25] for the equation to provide a valid answer

^notice KV change factor is, yet again, the square root of the conductance change factor as depicted

How many more examples are necessary to show that at constant copper volume, the change factor of KV is always the square root of the change factor of Conductance??
To be continued...
Wye
150kv = 100kv original wye x 1.5 [kv change factor 1.5] < more kv
19.24 turns = 28.86 original turns / 1.5 < less turns
2.59807 cross section = 1.73205 original cross section x 1.5 [keeps copper volume constant after turns reduction] < more cross section
1 copper volume < same copper volume
0.03688 ohm resistance leadtolead = (((original 0.0830 ohm)/1.5 [less turns])/1.5 [more cross section]) (0.01844 ohm VESC detection) [resistance change factor 0.44433...] < 0.44433 times as much resistance
27.11496 siemens conductance = original 12.04819 siemens x [2.25054 conductance change factor] = 1 / 0.03688 ohm < 2.25054 times as much conductance
Formula For ReWinding the 100 KV Wye to 150 KV Wye Keeping Same Copper Volume:
150kv = X [A] x 1 [B  Wye] x 19.24 [C]
This formula can be rearranged to:
A = 7.79625 = ( 2.25 x 3.46500 original Constant(motor) # )
^notice motor constant change factor [2.25] from original value is equal to conductance change factor [2.25054].
Therefore:
150kv = 7.79625 [A] x 1 [B  Wye] x 19.24 [C]
150 = 7.79625 x 1 x 19.24
150 = (2.25 x 3.46500 original Constant(motor) value) x 1 x 19.24
KV = 150
A = 7.79625 = (2.25 x 3.46500 original Constant(motor) value) = Constant(motor)
B = 1 = C(termination) < Must be 1 for Wye Wiring or 1.73205 [sqrt(3)] when Delta Wiring
C = 19.24 = turns
^Simply 19.24 turns wye gives 150kv

^So far matches my formula:
conductance change factor: 2.25054  12.04819 original siemens x 2.25054 conductance change factor = 27.11496 new siemens
kv change factor: sqrt(2.25054) = 1.50017  100 original kv x 1.50017 kv change factor = 150.0 new kv
notice motor(constant) number has necessarily increased by the same factor [2.25] as the conductance change factor [2.25] for the equation to provide a valid answer

^notice KV change factor is, yet again, the square root of the conductance change factor as depicted

How many more examples are necessary to show that at constant copper volume, the change factor of KV is always the square root of the change factor of Conductance??
To be continued...
Last edited by devin on 27 May 2017, 16:38, edited 1 time in total.
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