RC101: Motor timing explained

By HOBBYWING Admin
on September 22, 2020
Gary Karamikian, CEO at GK Systems inc helps explains how Motor timing works.  Let's learn from the best. 
 
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I have a lot of people ask me about what to do with Timing so let me help you understand how a 2 pole brushless motor works 

First, we need to know that there is a maximum that is possible, and any more than that actually will fight the motor.

There is a maximum possibility of only 60 deg of timing per phase. On a 2 pole brushless motor. And for reasons I will explain, we should not even try to go that high.

So let me explain, 3 phases A, B, C  & 2 poles on the rotor N & S.  So for 1 revolution (360 deg) there will be an A, B, C event for both North and South poles of the Rotor
So 6 total events in 360 deg of rotation
360/6 = 60

60 deg is the maximum degrees possible for each event 

Now take some transport delay and you are under 60 deg of revolution possible.

So really anything above 50 is dangerous 

Why is this important?

Because any timing on the end bell has to be taken into account when adding boost and turbo. 

Some manufacturers may have a safety limit in place others may not, but why take the chance and damage your motor and ESC. Not to mention trying to operate in a range that is not very effective or efficient.

I think it helps to know how things work when you try to modify/tune them.
 
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Who is Gary? 
Gary's firm focuses on electrification and the implementation of brushless motors in many different platforms from robotics to passenger cars.

His work in Hybrid electric systems has been used in the highest form of motorsport and can be found in Championship winning race cars all over the world, including the winner of the 24hrs of LeMans, the biggest race in the world. Brushless motor control is not only used for powering the vehicle but also used in stability control and performance-enhancing torque vectoring of the driven wheels.

GeryKaramikian.jpg

Highlights / Achievements

  • Winner of the 2012 24 Hrs. Of Le Mans In LMP2. With Starworks Motorsport
  • Winner of the 2017 Detroit Grand Prix and first-ever win for the Acura NSX GT3 race car
  • Winner of the 2017 6 Hrs. of the Glen and first-ever Endurance championship round win for the Acura NSX GT3 race car
  • Pole position and First ever Pole for the Acura NSX GT3 Race Car
  • Winner 2017 Pikes Peak Hill Climb, 2nd overall, New class record set with Realtime Racing
  • Winner of the 2016 Daytona 24 Hrs. (overall & Prototype category)
  • Winner of the 2016 12 Hrs. of Sebring (overall & Prototype category)
  • Winner of the 2016 10 Hrs. Petit LeMans (overall & Prototype category)
  • Winner 2012 ALMS P2 Championship with Level 5 Motorsports
  • Pole Position 2015 Daytona 24 with MSR in the inaugural running of Ligier JSP2 Car· Winner 2016 Mazda Raceway Laguna Seca with MSR Honda Liger JSP2, First win for Liger JSP2 car In North America

Gary can be reached at GK System Racing https://www.facebook.com/GKSystemsRacing/

News: SPAM ALERT

By HOBBYWING Admin
on September 21, 2020

Recently, we are informed that one of our dealers have received a suspicious message. Here we are again.  The sender's domain is NOT a HOBBYWING.com yet they are pretending like the message was sent from HOBBYWING N.A. 

We never ask anyone to provide us any invoice details, or credit-card information. If you receive a message like the image shown below, please simply delete it for report back to us at NorthAmerica@hobbywing.com  

Click the image to read the contents

RC101: Motor Talk and RC Racing 101 by Gary Karamikian

By HOBBYWING Admin
on September 18, 2020

Motor Talk and RC Racing 101

Hey guys I’m gonna to try and give you a very good explanation that hopefully will help a lot of people in regards to how Motors work. I do need everyone to read this because I can’t do it in just a few words.

First we need to understand what power is in relation to an electric motor. Power is measured in watts, Watts is equal to voltage of the battery times amps which is current. (W=V*I) V= Volts, I= current In amps (A) Now due to most rules, voltage is going to be somewhat fixed to a battery of 8.44 volts max.

Current on the other hand is the variable that we play with a lower turn motor that has less electrical resistance than a higher turn motor therefore a lower turn motor is physically capable of flowing more current through it. So for a fixed voltage a lower turn motor will naturally produce more power because it can flow more current than a higher turn motor. IE: If Volts are fixed then (power) W = 8.44 (V) x I (A) As Current (I) goes up power will go up, there is no debate there.

Here’s where things get tricky, The higher the current flow the greater amount of energy passes through the motor and because the motor is not 100% efficient, there will be a negative result in the form of excess heat. The longer the motor runs at a state of high current, the more heat will be generated. This is where gearing takes effect and why gearing is the most important thing you can do for your electric motor of any turn.

Now we need to understand that an electric motor will want to get to its natural state as quickly as possible. Its natural state is it’s KV wherever it’s set up. The Motor will try to achieve it's KV by pulling as much current as it can (limited by the speed controller) and when it gets closer to its natural speed it will pull less current. This is why full throttle bench motor tests pull between 2-12 Amps, but in the car on track you will see much more, especially in the early part of acceleration.

So for instance a 7700 KV motor will try to reach that state as quickly as possible. The gearing and weight of the vehicle slow this process down. So here’s the trick, the trick is to find a gear ratio that will allow the motor to accelerate to its natural state in the least amount of time. While achieving your desired trap speed in the desired ET all while trying to be controllable. If you are drag racing (hot topic these days) There is a limit though, geared too low and the motor will just rev out at max speed the entire duration of the pull and create heat and loose torque.

I know it's tempting but sometimes the lowest turn, highest KV motor is not gonna be desirable. If you’re set up, driving style, or whatever it is cannot manage or control the vehicle, then you will ultimately have a better ET with a motor set up that you can control. Everything comes down to gearing!

At the end of the day there are limitations, going too far in any direction will not be ideal. A happy balance is needed. Just as a very low turn motor might not always be the correct way to go, there is going to be a point where a very high turn motor will just not be able to accelerate regardless of whatever gearing you put on it.

Again balance is needed, in order to achieve the speed you’re looking for whether that is drag racing, on road or off road RC racing motor and gear combinations are key to having a successful outing.

So again the trick is to find a balance between a very powerful motor which for fixed battery voltage is always going to be in the direction of lower electrical resistance which equals lower turn rating. But that doesn’t necessarily mean that you and your car will be quicker with that set up. Going for the biggest fastest motor is not always the way to win!

I think understanding electrical motors and how they work will be very beneficial to everyone who’s trying to race an electric RC car. I hope this was informative to you guys. So remember at the end of the day it’s always best to just work up on gearing with whatever motor you have defined the balance between speed, ET, laptime and heat.

Key points, the higher the gearing the more time and current the motor is going to need to accelerate to its natural state. And because it wants to achieve its natural state it will pull more current and result in more torque! If you ever have a chance to Dyno an electric motor you will see torque fall off with current drop and this happens as it approaches its max speed. Which I think is opposite of what a lot of people believe, but a higher gearing will look to produce more torque out of the motor But it does come at the expense and penalty of heat and acceleration.

 

Article by Gary Karamikian CEO, GK Systems Inc

Happy Labor Day on Behalf of HOBBYWING North America

By HOBBYWING Admin
on September 05, 2020

Attention valued HOBBYWING customers,

In order for our staff to celebrate the holidays with family and friends, please review our holiday schedule.

  • Monday, September 7th

We will be Back Tuesday 8st September!

Last but not least, enjoy our annual sales event

We wish you and yours a safe and happy holiday!

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News: Happy Independence Day Weekend

By HOBBYWING Admin
on July 02, 2020

Hi everyone,

Observing the 4th of July, our office will be closed on Friday July 3rd.  Let's celebrate the holidays with family and friends

 

 

#WeAreWithYou

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