How Does an ESC work? What does the PWM Frequency Do and should I change it?

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  • เผยแพร่เมื่อ 7 ต.ค. 2024
  • Here is the basics of how an ESC works. We talk about electronic commutation within an ESC and we spend quite some time talking about PWM. Note that we are talking about the output drive of the ESC and not the input signal.
    PWM stands for pulse width modulation. It is an important function within an ESC in order to provide the speed variation between 0 and maximum RPM. Some ESC manufactures allow you to control the PWM frequency rate. But does this mean you should adjust the PWM frequency of the ESC? The common questions here are does the frequency rate allow the motor to perform faster? Output Higher RPM? Increase Efficiency? The quick answer is, you aren't going to gain more RPM by adjusting the PWM function.
    Higher PWM settings can increase responsiveness and smoothness for acceleration of the motor. In general the motor doesn't mind higher PWM settings, however the ESC will be doing more work to switch more rapidly.
    Required PWM settings is highly dependent on the application. If you want to know where you should be in terms of the setting, use the formula explained in the video. Otherwise if you are unsure, try out the ESC's default settings for your application and only make changes if you run in to issues.
    More details in the video!

ความคิดเห็น • 85

  • @oussamarmili4046
    @oussamarmili4046 2 ปีที่แล้ว +2

    Your explanations are very clear
    Thanks for the Video !

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว

      Thanks for the kind words.

  • @Hristovliverpool
    @Hristovliverpool 2 ปีที่แล้ว +1

    Great video! The subject is explained at depth and with just the right amount of detail. Thank you.

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว

      Thanks for the kind words Peter!

  • @mikemalherbe7845
    @mikemalherbe7845 4 ปีที่แล้ว +3

    Excellent info! Thanks for sharing your knowledge 😀

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว

      Thanks for the comment Mike!

  • @ret737
    @ret737 2 ปีที่แล้ว +1

    Can't thank you enough for your video. It helped explain a lot

  • @AJ-js1yw
    @AJ-js1yw 4 ปีที่แล้ว +1

    Good vid! Very theoretical with real world applications.
    Please correct me if I'm wrong but these are what i picked up:
    Lower PWM, hotter motor, more possible to cog.
    Higher pwm, cooler motorr, less cogging, hotter esc.
    Most of the time stock pwm doesnt need to be changed.
    If you do change it, compute it first.
    To make it short: don't change the pwm. 😁
    Thanks for this vid.

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว

      Hey James, sounds like you got it! The only thing I would say is change cog to smoothness and responsiveness issues. Generally speaking a motor would typically not have a problem with higher PWM settings at the cost of heat output from the ESC. Higher PWM settings can improve smoothness and responsiveness in the motor.
      Running the formula is a good way to start if considering changing the settings. This gives you an immediate baseline as to where the setting should be.

    • @AJ-js1yw
      @AJ-js1yw 4 ปีที่แล้ว

      @@RCexplained oooh, so (if you increase pwm) its not necessarily a cooler motor, its the usual temperature, but a relatively higher temp esc.
      Also, if you lower the pwm, its not a cooler esc, just the usual temp esc, but with a relatively hotter motor.
      ?
      Okay so smoothness and responsiveness got it.

  • @AceNZ1964
    @AceNZ1964 2 ปีที่แล้ว

    great explanation thanks sounds like 8k for my 4 pole boat and 12k for my 6 pole boat cheers from NZ
    I would love to see a test set up on a scope to show the wave forms between a cheep esc and a good one.

  • @DavidNakashidze
    @DavidNakashidze ปีที่แล้ว

    A great explainer, thanks!

  • @colin1992
    @colin1992 4 ปีที่แล้ว +2

    Great vid ryan!

  • @prasannarn946
    @prasannarn946 3 ปีที่แล้ว

    Finally. I get the answer to the questions around ESC after spending hours on Google. Awesome video. One question: How is the torque controlled? Or in other words how does the torque affect the motor RPM? Is it similar to a brushed DC motor?

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      Torque is not controlled. Speed is. As the motor is loaded RPM comes down.

  • @furiouswolf777voodoo4
    @furiouswolf777voodoo4 4 ปีที่แล้ว +2

    Thanks good video! I bought the castle link to adjust my esc. Do you have a video on making changes to esc settings? Praying you do lol. Anyway please stay safe and Thanks again for the great vids 💯😁

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว

      Hey Thanks! I do not have a video going through the settings of the ESC. This is a video that will be done in time. Its possible it would be a few months out.

    • @furiouswolf777voodoo4
      @furiouswolf777voodoo4 4 ปีที่แล้ว

      Ok good news. Thank you 🙂🙂

  • @funwithfamfun
    @funwithfamfun 3 ปีที่แล้ว

    Solid vid thanks!

  • @PIZZA_and_NITRO
    @PIZZA_and_NITRO 3 ปีที่แล้ว +1

    Thank you for another rc schooling, wondering if you mite do a comparison video between a well used motor and a new motor. Magnet strength, voltages' ability to travel intra motor when new compared to used, power feedback through the wires, how and why used motors seem to have a more static/ longer neutral point than a motor that is new. There's alot of used motors on the market for half the price of new, but the 'wear n tear' factor is not often looked at. If anybody can explain things like magnet strength depletion, a falling power curve and loss of rpm it's you ! Thanks!

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      Hey Mike. Very interesting. I have always assumed that electrically the motors don't really wear.(including the magnet) Mechanically, bearings can age and wear out. How many hours of usage would be considered a "well used motor?"

  • @KimAbraham
    @KimAbraham 3 ปีที่แล้ว +1

    Hello Ryan, first of all thanks for your videos, really interesting and very well explained.
    Small question on this one: on the whiteboard you drew a voltage curve that is ramping up and down. Isn't this achieved using shorter PWM pulses in reality (i.e. using pulse length to get to a lower average voltage)?
    Or are the FETs really sending a lower voltage to the motor?

  • @HappyDude1
    @HappyDude1 2 ปีที่แล้ว +1

    Hello
    For my rc tank i can change the khz with my custom elmod board
    Since the tank is very heavy and needs to drive slow and have a lot of torque what would be the best ? A high or a low khz ?
    The motor is non brushless

  • @dimos15
    @dimos15 3 ปีที่แล้ว

    Nice

  • @helmydewa
    @helmydewa 2 ปีที่แล้ว

    Hello Ryan, really enjoyed watching your videos... I just wanna ask, does this apply too in brushed ESC...?

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว

      Yes, it's a bit different but concept is identical

  • @jeanmariendour4871
    @jeanmariendour4871 3 ปีที่แล้ว

    Hi Ryan, thanks but i think you should divide by 120 not 20.
    f=(RPM*p)/120, this the formula we've always used at the university. The time needed for a slot to face another pole of the same type = (60/RPM)/(p/2)= 120/(p*RPM)=120/(p*KV*V).
    You invert it and you obtain the frequency

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว

      Hi Jean, in the formula that you have used, you have not used the commutation steps per electrical revolution. As a result, when calculating your PWM frequency, it will result in a lower frequency then the commutation frequency. This is the opposite relationship that you want. There is not much really to lose with a higher PWM frequency but that is not the case with a lower PWM frequency.

  • @zacharyohare6029
    @zacharyohare6029 2 ปีที่แล้ว

    Sooooo.... What I got from this is I could use brushed ESC to drive a DC induction 12v automotive fuel pump with PWM, so long as I converted a pressure signal to PWM? What frequency is the output signal of the receivers typically? (I could do brushless but I'm not a baller like that, the point is to be able to run a fat, cheap, single pump in the factory bucket, without it drawing 20+amps all friggen day...) Could also step up the voltage based on this. Essentially replicate what most modern fuel systems do for pressure control, but still have a regulator on the return. (it would just be set slightly higher than the pump's control pressure, as a default, where in the pump would be running wide open. Car would run rich enough it would be obvious something isn't right, but wouldn't fry a piston, and would be driveable to get to a safe place. Or could have a relay that just kills the pump. Is this a reasonable application for an old ESC? curious how reliable they would be. Haven't had a change to scope a few OEM FPCMs to see what they like for input to kick on.

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว

      The video discusses the output from esc to motor. Not receiver to esc. A simple servo tester can control an esc.

  • @madl3x
    @madl3x 2 ปีที่แล้ว

    From where do we get that constant (20) that you use to divide the PWM frequency formula?
    If I plug in your formula for a 4S (14.8V) whoop and a 4500 kV motor I get 46.6 kHz optimal PWM Frequency. So for whoops, 48kHz is the right frequency?! Not all ESCs support this.

  • @33gate1
    @33gate1 2 ปีที่แล้ว

    Please confirm, My helicopter motor is 520KV , Magnet Poles 10 , 12s lipo 44.4V. So 44.4 X 520 X 10 = 230 880 / 20 = 11.544, so my PWM should be 12Khz? Align T-Rex 800MX Brushless Motor(520KV) + Castle Phoenix Edge HV 120 Brushless ESC

  • @gregstafford2155
    @gregstafford2155 4 ปีที่แล้ว +1

    Can you turn this theory into practice using a RC dyno with different motors for comparisons? 👍

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว +1

      Hey Greg, that's the plan for many of the videos that have been posted. I want to demonstrate these theoretical approaches using the appropriate motors etc. I have some limitations to work through until I can get there. A major limitation is equipment. A good example is even this particular video. I do not have a setup that actually requires a higher PWM setting then factory.

  • @syncprism6283
    @syncprism6283 4 ปีที่แล้ว +1

    Thank you for the great video! If the ESC controls only the "average" voltage (since pwn is rapid on/off) to the motor, and current is not "controlled" by the ESC but instead determined by load of the motor, then can I say that ESC does NOT directly control the power of motor nor the speed of it? BTW kv is only accurate as per voltage when there is no load, and with higher load the motor can meet the power limit sooner than reaching its kv-denoted highest speed right?

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว +1

      The ESC controls the speed of the motor. kv accuracy is not required in order to control speed. The controller simply provides an on/off duty cycle, it's not a closed loop system checking and confirming that 10,000RPM was reached. A higher load could result in a slower speed at the same duty cycle.

    • @syncprism6283
      @syncprism6283 4 ปีที่แล้ว

      @@RCexplained Understood. Thank you so much!

  • @cccagley5276
    @cccagley5276 3 ปีที่แล้ว

    This seems to apply to planes and cars not necessarily quadcopters. My micro quads use 24khz or 48khz. In fact the higher 48khz is MORE efficient for very small, very high kv setups.

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว

      What did you calculate using the formula?

  • @FourthWayRanch
    @FourthWayRanch ปีที่แล้ว

    how can we measure a throttle pwm signal without an osciliscope?

  • @morgangriffiths1023
    @morgangriffiths1023 3 ปีที่แล้ว

    Hey Ryan thank you for making such informative videos I have a question though,
    Does motor winding type come into play when selecting PWM timing?

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      Hi, thanks for the comment. Motor winding type a variable that changes the kv value. It is already captured.

  • @desafioaceito1
    @desafioaceito1 3 ปีที่แล้ว

    Awesome! I thought that ESC were controlled using PPM instead of PWM signals. Is PWM the correct type of signal to input in the signal cable of the ESC?

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      Note that the PWM frequency mentioned in the video is for the output to the motor.

  • @kamuranpeker132
    @kamuranpeker132 2 ปีที่แล้ว

    So if we set the esc frequency to a lower value than it should be, what kind of troubles will we get?

  • @MassiveINC1
    @MassiveINC1 2 ปีที่แล้ว

    i have a pixhawk cube FC for my Hexacopter. i was running 200 amp madX escs' , when i switched to 500 amp Flier model escs" they wouldn't receive a signal. i checked the escs' by running a direct wire from futaba receiver to one esc and it worked fine. Why don't the bigger flier model escs receive signal from the pixhawk, but the madX escs do? any info is greatly appreciated. thanks.

  • @Lokeshkumar-zq2ye
    @Lokeshkumar-zq2ye 2 ปีที่แล้ว

    Hi,
    Can you make a video on how to programm an esc without a program card and without a radio controller. Because I'm puzzled on how the esc is taking inputs, in the manul its given to move the throttle up later power up esc and wait for some time it will end up in program mode, but the same procedure I did it with a servo tester, for an esc it should not matter if it's a transmitter or a servo driver has long has its receiving the inputs, but for some reason my esc never went to program mode so just puzzled, it would be great if you helped me out.

  • @jgm911t
    @jgm911t 2 ปีที่แล้ว

    I calculated from your formula 3770 x 14.8 x 4) = 11,159 Hz and having issues at 12 kHz. Is it too close to 12kHz?

  • @lazyFatCyclist2
    @lazyFatCyclist2 4 ปีที่แล้ว +1

    Why the division by 20 in the formula for frequency?

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว +1

      I can't remember the formula off the top of my head, however, its the amount of commutation cycles with a factor to get the PWM frequency away from this value.

  • @gkdresden
    @gkdresden 8 หลายเดือนก่อน

    This formula for the PWM frequency says nothing else than you should have at least 1 pwm pulse within 1 PM pole N-S transit along of 1 stator pole. I personally would rather work with at least 2 or 4 pulses within 1 PM pole N-S transit to get a smoother motor behavior.

  • @abhijeetdhillon9591
    @abhijeetdhillon9591 4 ปีที่แล้ว

    HEY NICE VIDEO !! I HAVE A DOUBT IF WE HAVE 24 VOLT BATTERY , DOES 100% THROTTLE MEAN 100% DUTY CYCLE MEANING 24 VOLTS APPLIED ?

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว

      24v is always the applied voltage from the ESC if the battery is 24v, however the motor will "see" the average based on the duty cycle. At full throttle, duty cycle is 100%, motor sees source voltage.

    • @abhijeetdhillon9591
      @abhijeetdhillon9591 4 ปีที่แล้ว

      @@RCexplained SO 50% THROTTLE MEANS 12 VOLTS TO MOTOR?

  • @revee1000
    @revee1000 2 ปีที่แล้ว

    Not sure if you still answer old video questions. My esc came set at 1000 hz. I'm running a 3300 kv 4 pole on 3s it came to 7326 so should I change it to 8 kHz?

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว +1

      I dont get to all the questions.
      Confirm that the 1000Hz is the pwm frequency. I haven't seen one being so low before. Most escs are at atleast 8000hz or 12000hz. Change to 8khz if confirmed.

    • @revee1000
      @revee1000 2 ปีที่แล้ว

      @@RCexplained thank you . On my program sheat the adjustability is from 1 thru 8 starts at 16KHz to 125 Hz . It is a cheap 80 amp esc. I don't have any equipment to test it

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว +1

      @@revee1000 16KHz will be fine.

  • @96vmax4
    @96vmax4 2 ปีที่แล้ว

    I have an edf motor that is a bit puzzling. 2250kv, 6s 22.2v, 12 poles. Would this require an esc that can to 32k?

    • @RCexplained
      @RCexplained  2 ปีที่แล้ว

      Yes most high performance motors used in high powered EDFs are inrunners with a 4 pole rotor.

    • @96vmax4
      @96vmax4 2 ปีที่แล้ว

      @@RCexplained my edf units use a 12 pole out runner

    • @96vmax4
      @96vmax4 2 ปีที่แล้ว

      @@RCexplained they are jp 70mm 6s edf units. For some reason jp says they require certain esc to run. Is that due to and the extremely high switching rate?

  • @chris-ip4pk
    @chris-ip4pk 3 ปีที่แล้ว

    Hi ,my motor states drive frequency is 8khz and 15 timing,my esc has 12 or 18 timing and it says pwm 8khz up to 16khz,my question is what should I set timing to 12 or 18 and is pwm frequency same as the motor drive frequency, please help

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว

      drive frequency would be PWM frequency. Try a timing of 12 and measure performance. do the same with 18. select best

  • @RechlerDudi
    @RechlerDudi 3 ปีที่แล้ว

    Hi Ryan, great video. I'd love to have your opinion: Just finished a new quadcopter build. I'm using Blheli32 ESCs and 935kv brushless motors. When testing the system, 3 of the motors seems to be ok but the 4th is just jumping back and forth not getting into smooth rotation to either direction. Any idea? Settings / esc problem / motor problem (all components are new). Thanks!

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      Test another working motor connected to that ESC to see if it is the motor acting up. Also test another working ESC to see if it is able to spin up the hesitating motor. This should provide you with some insight to see what the problem could be. Motor vs ESC

    • @RechlerDudi
      @RechlerDudi 3 ปีที่แล้ว

      @@RCexplained That's the plan for tomorrow as it is almost midnight here 😉. Can it be a sync issue? Should I change anything on the blheli32 suit for that esc (in case it causes the same effect on a different motor?)
      And thanks for the fast response!

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      I would not do anything until cross checked with known working equipment. If you didn't have to change anything on the 3 other setups, the fourth should be no different.

    • @RechlerDudi
      @RechlerDudi 3 ปีที่แล้ว

      @@RCexplained ok, you were right. Swapped motors and seems like it's the motor's fault. Another motor with the original esc works fine.
      I also tried to play with the esc parameters to get the faulty motor to work and managed to get it spinning at half throttle for a while but there were lots of vibrations and it got warm so I stopped. Do you think there is anything I can do with that motor? (Brand new, though an EMAX so not an impressive quality...)

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      Spin the motor up with a drill and measure the back EMF of each phase. If they are not the same within a close tolerance, there's not much you can do. Look up my Determining Kv with a Drill Video from a couple years ago if you are unfamiliar with this process.

  • @vahagnmelikyan2906
    @vahagnmelikyan2906 3 ปีที่แล้ว

    Does that 12 default apply to brushless motor or also to dc motor?

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว

      12kHz is the PWM frequency of the ESC to the brushless motor. I don't use brushed DC motors/ESC;s too often these days to comment on them.

  • @LawrenceTimme
    @LawrenceTimme 4 ปีที่แล้ว

    What's the point in all the other settings then if they don't do anything, surely the manufacturer wouldn't let you change them if they made no difference?

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว

      Hey Lawrence, from my own (limited) experience, I have not come across a setup that requires a different PWM setting on the ESC. Surely there are many setups that require different settings, however, it will be a low percentage overall. I ran through the calculation in the video of a couple of my own setups, but I'm sure I can find values that will theoretically require a different setting. Have you ever required to change the PWM setting?

    • @LawrenceTimme
      @LawrenceTimme 4 ปีที่แล้ว +1

      @@RCexplained I don't think any of my escs have it as a changeable setting, but on computers I know you can change the pwm frequency for the VRM which powers the cpu. When overclocking it can increase the stability a lot under higher current and voltage. The VRM on the motherboard does run warmer because of this.
      I have seen some more race oriented escs you can change the pwm frequency separately on both the brake and normal forward driving of the car.

    • @shadow7037932
      @shadow7037932 4 ปีที่แล้ว

      ​@@RCexplained For RC cars, PWM frequency doesn't really matter much like you said. But for RC quads, especially racing quads where very fast and small changes are made by the flight controller, a higher PWM setting can help depending on motor, ESC, flight controller combination.

    • @RCexplained
      @RCexplained  4 ปีที่แล้ว

      @@shadow7037932 yes, formula would help out with the high RPM and Pole count that are commonly found in quads.

  • @vahagnmelikyan2906
    @vahagnmelikyan2906 3 ปีที่แล้ว

    Hi I have a pwm signal controller. It has a digital display(that's necessary for my project). It has a frequency choice and duty cycle (I get confused between these two). Can I attach the pwm signal to the ESC controller for brushless motor? The PWM controller has a +- voltage output. I need it for a mini blower fan. The ESC 3 wires connect to the brushless motor, but not sure how I should connect the pwm signal to the ESC

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว +1

      In the video we were talking about the output PWM frequency that the ESC uses to drive the motor. I don't remember touching on the input to the ESC as it seems you are interested in. Generally the input requirement is about a 4-6V peak to peak square wave pulse. Pulse length or duration is 0.9mS to 2.1mS. The pulse refreshes at 50Hz or 20mS.

    • @vahagnmelikyan2906
      @vahagnmelikyan2906 3 ปีที่แล้ว

      @@RCexplained so what would happen if I connect 5v dc input into the ESC speed controller without pwm, or any frequency. Wouldn't the esc still work to control the motor?

    • @RCexplained
      @RCexplained  3 ปีที่แล้ว

      @@vahagnmelikyan2906 to control the esc you would have to supply the correct signal through the 3 lead radio wire of the esc.