Kv vs.Synchronous RPM
12-10-2015, 02:13 PM
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Kv vs.Synchronous RPM
Hello,
I am new to Electric flight.
Since brushless motors are essentially 3 phase motors, why is the RPM related to voltage, as in KV?
The ESC generates a 3-phase control that must force the motor to rotate at a synchronous RPM, regardless of the voltage (within limits of course).
If a 3-phase motor can't stay synchronous to the ESC, then it will operate at a very low efficiency as it tries to "catch-up" with the ESC driving frequency.
Therefore, as I read in one forum, "KV is RPM per volt at, no load, installing a prop will load the motor with consequently lower RPM".
What happened then with the synchronous drive from the ESC?
Shouldn't the motor RPM remain constant with different loads as long as the ESC driving frequency does not change?
Dan
I am new to Electric flight.
Since brushless motors are essentially 3 phase motors, why is the RPM related to voltage, as in KV?
The ESC generates a 3-phase control that must force the motor to rotate at a synchronous RPM, regardless of the voltage (within limits of course).
If a 3-phase motor can't stay synchronous to the ESC, then it will operate at a very low efficiency as it tries to "catch-up" with the ESC driving frequency.
Therefore, as I read in one forum, "KV is RPM per volt at, no load, installing a prop will load the motor with consequently lower RPM".
What happened then with the synchronous drive from the ESC?
Shouldn't the motor RPM remain constant with different loads as long as the ESC driving frequency does not change?
Dan
01-10-2016, 06:24 AM
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Join Date: Sep 2002
Location: Nijmegen / Nederland
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Dan,
Please, do your RC equipment, wallet, ego, house/garage/car a big favour ... get a watt-meter. It will more than pay for itself, will save you at least one fried motor and one fried controller. Will also help you finding the best setup.
Some reading for rainy/windy days. Will save you, and us
, a lot of questions.
Will also prevent you from burning up several controllers and/or motors and/or battery.
E-flight 101 by RCG member Ken Myers, will at least save you a ruined LiPo (or worse!), a burnt motor and a fried ESC:
The Ampeer
→ Electric Power Basics (Ken Myers)
Table of Contents, a.o.
About charge, current, voltage, resistance, power, energy
www.powerwerx.com/techdata/Watts-UP-V2.pdf
Basics of electricity
→ page 7-10
followed by
The Ampeer
→ Everything youw wanted to know about e-flight (Ed Anderson)
Table of Contents, a.o.
Multiple choice wiring diagrams, charger selection tools, instructive demo's, calculators ...
www.scriptasylum.com
→ RC calculations
→ electrical
→ system wiring
respectively ...
→ LiPo pack wiring
respectively
→ chargers (2 menu items)
The other menu items and demos are also veeeeery handy/instructive for e-folk, add site to your favourites?
Vriendelijke groeten
Ron
p.s. I took some liberties with the table of contents, they are not complete.
Please, do your RC equipment, wallet, ego, house/garage/car a big favour ... get a watt-meter. It will more than pay for itself, will save you at least one fried motor and one fried controller. Will also help you finding the best setup.
Some reading for rainy/windy days. Will save you, and us
, a lot of questions.Will also prevent you from burning up several controllers and/or motors and/or battery.
E-flight 101 by RCG member Ken Myers, will at least save you a ruined LiPo (or worse!), a burnt motor and a fried ESC:
The Ampeer
→ Electric Power Basics (Ken Myers)
Table of Contents, a.o.
- Recommended First Purchase - Power Meter & How to Use it
- About Chargers & LiPo Batteries
- Power Lead Connectors and Wire
- ... ... ...
- Brushless Electronic Speed Controls (ESC) Basics, LVC and BEC
- Motors for Electric Flight, Kv, Timing, Efficiency, Props
- Safety Precautions
About charge, current, voltage, resistance, power, energy
www.powerwerx.com/techdata/Watts-UP-V2.pdf
Basics of electricity
→ page 7-10
followed by
The Ampeer
→ Everything youw wanted to know about e-flight (Ed Anderson)
Table of Contents, a.o.
- What You Need To Know About Receivers
- Battery Basics, Battery Chargers
- Amps Versus Volts Versus C
- ... ... ...
- Understanding the Electronic Speed Control (ESC)
- Sizing Power Systems for Electric Airplanes, Prop Versus Amps
- What Do the Kv Numbers On Motors Mean?
- Who Needs a Wattmeter/Powermeter?
(Everyone! But don't buy one if you plan on sponsoring motor and ESC manufacturers RvS)
Multiple choice wiring diagrams, charger selection tools, instructive demo's, calculators ...
www.scriptasylum.com
→ RC calculations
→ electrical
→ system wiring
respectively ...
→ LiPo pack wiring
respectively
→ chargers (2 menu items)
The other menu items and demos are also veeeeery handy/instructive for e-folk, add site to your favourites?
Vriendelijke groeten
Ronp.s. I took some liberties with the table of contents, they are not complete.
