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Old 01-13-2019, 04:04 PM
tinker777 is offline
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out runner motors

????...outrunner motors are AC or DC, and if its AC does the ESC take the battery and turn the power into AC
thanks
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Old 01-13-2019, 05:06 PM
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They're get'n lower mate.....
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The ESC produces a synthetic 3 phase sign wave....... varying frequency & voltage
The high pitched squeal one hears are the back iron harmonics fighting due to pitch / cord factor being to short
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Old 01-14-2019, 02:41 PM
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thank you
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Old Today, 11:17 AM
ron_van_sommeren is offline
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The motors are PM BLDC motors, Permanent Magnet Brushless DC.

Outrunners are inrunners turned inside out, no electrical difference between the two.
See also these
brushless motor animations and simulations - RCG

A brushless motor is a brushed motor with electronic switching (the ESC) instead of mechanical switching (commutator+brushes).

A brushless motor+ESC behaves the same as a brushed motor, same formulas for rpm, current and power drawn apply.
A motor acts at the same time as a generator, the controller uses the generated voltages to determine when to switch/commutate. The motor is the boss, ESC frequency follows motor rpm.

The threemotor/ESC wires are equivalent, but not identical. They carry the same power signal albeit with a 120degree phase ('time') difference. The colours are a handy reminder/help.

You can connect them anyway you want. If motor runs in the wrong direction, just swap any two of the three motorwires. NEVER EVER swap battery wires, reverse batery polarity will ruin you controller, bigly, in the blink of an eye
Different colours for motorwire are handy for remembering theESC→ motor connections.


The ESC modulates the voltage going to the motor windings in proportion to the stick value.
Explanation
Pulse-width modulation (wikipedia)

Power signals at full throttle, no chopping up voltage in pieces. Trapezoid commutation.



Power signals at partial throttle, PWM chopping ('grass') to reduce effective voltage.


Scope traces from www.aerodesign.de/peter, DIY brushless motor building (english&german)
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Last edited by ron_van_sommeren; Today at 11:38 AM.
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Old Today, 11:30 AM
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uomo ludens modellesticus
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It's all about what the motor wants to do versus what the motor can do.
Kv says nothing about power and torque.
Kv matches rpm and voltage, nothing more.
Kv and voltage determine how fast motor wants to run.
  1. rpm_noload = voltage × Kv
  2. Rpm and prop determine torque, torque in turn determines current.
    current = torque × Kv (in SI units!)
  3. Max.current and max.power determine whether that voltage/motor/rpm/prop combo can run without going up in smoke.

Prettig weekend Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
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Old Today, 11:31 AM
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uomo ludens modellesticus
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General rules for current and power, they give a relative indication:
Motorcurrent is proportional to pitch¹, voltage², Kv³ and diameter⁴.
Power-drawn is proportional to pitch¹, voltage³, Kv³ and diameter⁴.

Voltage effect without the exponentiation
extra current with one or two cells added, simple table



Therefore, changes in setup (and lousy Kv specifications!) can have surprisingly huge effects.
E.g. doubling voltage will four(2²)fold current, doubling Kv will eight(2³)fold current, and doubling prop diameter will sixteen(2⁴)fold current.
Even a small 10% change/difference in Kv will already lead to a 30% difference in current.



Always check/measure current in a changed/new setup.

Vriendelijke groeten Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
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