Brushless mini lathe motor torque chart compare to DC motors.?

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I know the DC motors have very high torque as the motor slow down.? The standard ac squire cage motor is about same the rpm's drop off.?

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But do not know what torque is on the Brushless electronic DC motors?.?

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Dave?

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Thank posting the link

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By there chart looks like there selling brushless motors.

Why would a chart of different rpm's and horses power.?

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The only motor I know they got right was AC type motor.?

AC motors have very narrow range typically between 3% to 10% slip. They do make motors with zero slip.

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Dave?

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On Tue, Jul 16, 2024 at 03:08 PM, WAM wrote:

When look at chart?

The universal motor at 20,000 rpm. Torque is about best you use drill and pipe threading machine. There chart show a poor curve.?

Why show a Brush motor run at 2,500 rpm when there is Brushless is around 4,000 rpm.?

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The AC motor has a range of 5 to 10% on most I see running 3,600 rpm on this has lot of variation for torque from fans to air compressors.? The rpm is only 3 600 to 3,450 type. There chart show a lot higher rang.

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Dave?

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On Tue, Jul 16, 2024 at 03:08 PM, WAM wrote:

Any time some chartbi look at want do know and see fits.

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Dave?

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On Tue, Jul 16, 2024 at 08:32 PM, Tony Smith wrote:

They designed to look great.

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Dave?

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On Tue, Jul 16, 2024 at 10:06 PM, Tony Smith wrote:

Do you own a Brushless motor?

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Dave?

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On Tue, Jul 16, 2024 at 10:06 PM, Tony Smith wrote:

Here are 2 chart on brushless motors. If notice they different rpm curves. They a low cost motors because of wide spread.?

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This chart is on a typical permanent magnet motors.

If noticed the wide range .?

There is no real slip in DC motors just torque to rpm .

If notice the effective drop a lot. But but motor slows down the torque goes up.?

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I am still looking for good chart on motors use machine tools like mini lathe.?

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Remember the difference between brush vs brushless?

Thd brushless uses a 3 phase motor and the controller changes the frequency?

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Dave?

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On Tue, Jul 16, 2024 at 10:06 PM, Tony Smith wrote:

A brushless DC motor uses a VDF and 3 phase motor.

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The best part of brushless type s is they very low maintenance and last long time.

The best part brush type is as motor slow down you get greater torque.?

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When look graphs from a company there graphs are wild.

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I have on some things brushless just not on my mini lathe and try find true graphs

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Here a graph on AC motors very little different between single and three phase. Note the brushless use a 3 phase motor. FYI In computer a 2 phase is use so curve is flater I think.?

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The graph shows the curve.?

Thd lower one is a schematic of brushless motors.?

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Here torque chart of brush DC motor.

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Dave?

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What pros and cons of both that I do not see beyond the advertising junk?

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Dave?

I prefer to think of a BLDC motor as any other DC motor. The difference between a brushed and a brushless motor is simply that in a brushed motor the commutation is done mechanically by the combination of brushes and commutator, and in a brushless motor it is done by solid state electronics. Physically they work the opposite way, the coils are fixed and the magnets spin, but they are still governed by the same equations that link voltage, current, RPM, torque and efficiency using the same set of coefficients, only the typical values of those coefficients are different to reflect the different construction involved.

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The advantage of a brushless motor is that it eliminates the moving parts involved in the commutator. The point of contact of the brushes can skip (leading to arcing), requiring a spring pressure and consequent resistance to turning (which can be reduced by material choice but not eliminated) and introduces electrical resistance that lowers the motor's efficiency under load compared to a well designed solid state commutator that has resistances in the low milliohms or even lower. Obviously wear of the brushes and commutator is not a factor. Also in the case of an "in-runner" brushless motor, the windings are glued to the outer case of the motor making it easy to conduct heat away from the windings.

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There are 2 flavors of brushless motor. Some use a sensor (hall effect or optical) to detect the orientation of the magnets, they behave almost identically to brushed DC motors (except with typically higher efficiency), while sensorless brushless motors try to determine the position of the magnets based on the behavior of the windings and the voltage induced by the spinning magnets. This doesn't work well at low RPMs so sensorless brushless controllers use a startup mode that works without feedback initially (very much like a synchronous AC motor) until there is enough information coming back from the windings to allow proper commutation. Because of this. motors with sensors have better low RPM behavior and can start reliably at high torque. They cost a little more because of the additional cost of the sensor. (But sensorless motors have improved over the past 2 to 3 decades. so I might be overselling the difference.)

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- Rob.

Thank you for your links

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I know most do not know motor in electronics.? I have also run cross 2 phase motors on some hard drives.?

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What I am look at size a brushless motor on my mini lathe that has a brush type motor torque at lower speeds.

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The brush type motors have greater torque as more power need but motor slows down. The control board just adds more voltage to keep the speed the same but increased the torque.?

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Now the brushless uses frequent to change speed.?

So torque says the same at high speed and low speed.?

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Finding graphic showing is a big problem to figure out the correct size replacement?

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Dave?

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On Fri, Jul 19, 2024 at 08:40 AM, WAM wrote:

No - still the same.? A great example of a sensorless is the DVD/CD
player - you can here it spin up, then drop to the proper RPM.

BLDC motors are electrically "commutated" with speed control via either
a sensor or back EMF.



where:
"There? are? two? torque? parameters? used? to? define? a
BLDC? motor,? peak? torque? (TP)? and? rated? torque
(TR). During continuous operations, the motor can be
loaded up to the rated torque.
In a BLDC motor, the torque remains constant for a
speed range up to the rated speed. The motor can be
run? up? to? the? maximum? speed,? which? can? be? up? to
150%?? of?? the?? rated?? speed,?? but?? the?? torque?? starts
dropping. "






Sensorless




Commutation methods:


Trapezoidal commutation:


FOC:


Sinusoidal control


My retrofit of using a Consew BLDC on a MaxNC CNC:

On my Deckel Clone:




On 7/19/2024 10:57 AM, robfliesrc via groups.io wrote:

I prefer to think of a BLDC motor as any other DC motor. The difference between a brushed and a brushless motor is simply that in a brushed motor the commutation is done mechanically by the combination of brushes and commutator, and in a brushless motor it is done by solid state electronics. Physically they work the opposite way, the coils are fixed and the magnets spin, but they are still governed by the same equations that link voltage, current, RPM, torque and efficiency using the same set of coefficients, only the typical values of those coefficients are different to reflect the different construction involved.

The advantage of a brushless motor is that it eliminates the moving parts involved in the commutator. The point of contact of the brushes can skip (leading to arcing), requiring a spring pressure and consequent resistance to turning (which can be reduced by material choice but not eliminated) and introduces electrical resistance that lowers the motor's efficiency under load compared to a well designed solid state commutator that has resistances in the low milliohms or even lower. Obviously wear of the brushes and commutator is not a factor. Also in the case of an "in-runner" brushless motor, the windings are glued to the outer case of the motor making it easy to conduct heat away from the windings.

There are 2 flavors of brushless motor. Some use a sensor (hall effect or optical) to detect the orientation of the magnets, they behave almost identically to brushed DC motors (except with typically higher efficiency), while sensorless brushless motors try to determine the position of the magnets based on the behavior of the windings and the voltage induced by the spinning magnets. This doesn't work well at low RPMs so sensorless brushless controllers use a startup mode that works without feedback initially (very much like a synchronous AC motor) until there is enough information coming back from the windings to allow proper commutation. Because of this. motors with sensors have better low RPM behavior and can start reliably at high torque. They cost a little more because of the additional cost of the sensor. (But sensorless motors have improved over the past 2 to 3 decades. so I might be overselling the difference.)

- Rob.

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On Fri, Jul 19, 2024 at 08:40 AM, WAM wrote:

No - still the same.? A great example of a sensorless is the DVD/CD
player - you can here it spin up, then drop to the proper RPM.

BLDC motors are electrically "commutated" with speed control via either
a sensor or back EMF.



where:
"There? are? two? torque? parameters? used? to? define? a
BLDC? motor,? peak? torque? (TP)? and? rated? torque
(TR). During continuous operations, the motor can be
loaded up to the rated torque.
In a BLDC motor, the torque remains constant for a
speed range up to the rated speed. The motor can be
run? up? to? the? maximum? speed,? which? can? be? up? to
150%?? of?? the?? rated?? speed,?? but?? the?? torque?? starts
dropping. "






Sensorless




Commutation methods:


Trapezoidal commutation:


FOC:


Sinusoidal control


My retrofit of using a Consew BLDC on a MaxNC CNC:

On my Deckel Clone:




On 7/19/2024 10:57 AM, robfliesrc via groups.io wrote:

I prefer to think of a BLDC motor as any other DC motor. The difference between a brushed and a brushless motor is simply that in a brushed motor the commutation is done mechanically by the combination of brushes and commutator, and in a brushless motor it is done by solid state electronics. Physically they work the opposite way, the coils are fixed and the magnets spin, but they are still governed by the same equations that link voltage, current, RPM, torque and efficiency using the same set of coefficients, only the typical values of those coefficients are different to reflect the different construction involved.

The advantage of a brushless motor is that it eliminates the moving parts involved in the commutator. The point of contact of the brushes can skip (leading to arcing), requiring a spring pressure and consequent resistance to turning (which can be reduced by material choice but not eliminated) and introduces electrical resistance that lowers the motor's efficiency under load compared to a well designed solid state commutator that has resistances in the low milliohms or even lower. Obviously wear of the brushes and commutator is not a factor. Also in the case of an "in-runner" brushless motor, the windings are glued to the outer case of the motor making it easy to conduct heat away from the windings.

There are 2 flavors of brushless motor. Some use a sensor (hall effect or optical) to detect the orientation of the magnets, they behave almost identically to brushed DC motors (except with typically higher efficiency), while sensorless brushless motors try to determine the position of the magnets based on the behavior of the windings and the voltage induced by the spinning magnets. This doesn't work well at low RPMs so sensorless brushless controllers use a startup mode that works without feedback initially (very much like a synchronous AC motor) until there is enough information coming back from the windings to allow proper commutation. Because of this. motors with sensors have better low RPM behavior and can start reliably at high torque. They cost a little more because of the additional cost of the sensor. (But sensorless motors have improved over the past 2 to 3 decades. so I might be overselling the difference.)

- Rob.

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On Fri, Jul 19, 2024 at 08:40 AM, WAM wrote:

No - still the same.? A great example of a sensorless is the DVD/CD
player - you can here it spin up, then drop to the proper RPM.

BLDC motors are electrically "commutated" with speed control via either
a sensor or back EMF.



where:
"There? are? two? torque? parameters? used? to? define? a
BLDC? motor,? peak? torque? (TP)? and? rated? torque
(TR). During continuous operations, the motor can be
loaded up to the rated torque.
In a BLDC motor, the torque remains constant for a
speed range up to the rated speed. The motor can be
run? up? to? the? maximum? speed,? which? can? be? up? to
150%?? of?? the?? rated?? speed,?? but?? the?? torque?? starts
dropping. "






Sensorless




Commutation methods:


Trapezoidal commutation:


FOC:


Sinusoidal control


My retrofit of using a Consew BLDC on a MaxNC CNC:

On my Deckel Clone:




On 7/19/2024 10:57 AM, robfliesrc via groups.io wrote:

I prefer to think of a BLDC motor as any other DC motor. The difference between a brushed and a brushless motor is simply that in a brushed motor the commutation is done mechanically by the combination of brushes and commutator, and in a brushless motor it is done by solid state electronics. Physically they work the opposite way, the coils are fixed and the magnets spin, but they are still governed by the same equations that link voltage, current, RPM, torque and efficiency using the same set of coefficients, only the typical values of those coefficients are different to reflect the different construction involved.

The advantage of a brushless motor is that it eliminates the moving parts involved in the commutator. The point of contact of the brushes can skip (leading to arcing), requiring a spring pressure and consequent resistance to turning (which can be reduced by material choice but not eliminated) and introduces electrical resistance that lowers the motor's efficiency under load compared to a well designed solid state commutator that has resistances in the low milliohms or even lower. Obviously wear of the brushes and commutator is not a factor. Also in the case of an "in-runner" brushless motor, the windings are glued to the outer case of the motor making it easy to conduct heat away from the windings.

There are 2 flavors of brushless motor. Some use a sensor (hall effect or optical) to detect the orientation of the magnets, they behave almost identically to brushed DC motors (except with typically higher efficiency), while sensorless brushless motors try to determine the position of the magnets based on the behavior of the windings and the voltage induced by the spinning magnets. This doesn't work well at low RPMs so sensorless brushless controllers use a startup mode that works without feedback initially (very much like a synchronous AC motor) until there is enough information coming back from the windings to allow proper commutation. Because of this. motors with sensors have better low RPM behavior and can start reliably at high torque. They cost a little more because of the additional cost of the sensor. (But sensorless motors have improved over the past 2 to 3 decades. so I might be overselling the difference.)

- Rob.

I need to add to last post on the brushless motor

Some manufacturers will use larger motor and keep the two speed belting?

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Dave?

I did find a graph for VFD aka brushless motors.??

There two charts one showing at giving frequency the other chart and different frequency/rpm high and low speed.?

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This on the DC pm motor.

Note high speed on this is switch high on left and low on right

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By comparing the charts you figure the correct replacement motor.

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Dave?

The high speed spindle speed of 2,000 rpm the motor speed is 6,000 rpm is 100 cycles per seconds.

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Low spindle speed of 100 rpm motor is 300 rpm and 5 cycles per seconds.?

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DC motors just adds more voltage to keep same rpm.?

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Hope helps?

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Dave?

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