Prototype production phase done. Testing phase starting. Production phase started.



1. Introduction:

First BLDC motor was developed in 1962 by T.G. Wilson and P.H. Trickey unveiled what they called “a DC machine with solid state commutation”, it was basically because solid state thyristors appeared on the scene.
A permanent-magnet synchronous motor (PMSM) uses permanent magnets embedded in the steel rotor to create a constant magnetic field. The stator carries windings connected to an AC supply to produce a rotating magnetic field. At synchronous speed the rotor poles lock to the rotating magnetic field. Permanent magnet synchronous motors are similar to brushless DC motors.
The difference between BLDC and PMSM is that BLDC is driven by square waveform and PMSM is drive with a sine wave current.
 These motors require a variable-frequency motor inverter, ESC,  Frequency inverter.

With a strong background from Polytechnic University, Faculty of Electrical Engineering, electrical machines discipline, I started  10 years ago to modify some BLDC motors, and then designing my own. 

After making my own electric car conversion Opel Agila:, i got enough experience to understand what are the motor needs for an electric car.

A motor should have high range of RPM and high peak capacity to be able to keep the car in one (gear) second or third, and have 120km/h at 7000RPM for example.
Many simulations were done until the final version (after about 50 simulations with various magnets sizes, angles, dimensions, stator tooth sizes and shape, and different winding configuration. 
To be able to have a very small cogging torque and a sinewave back EMF the motor is consisted in three rotor slices with 3 degrees skewing; this also reduces harmonics and eddy currents losses in the magnets. The motor will work with sensorless sinewave controller or using resolver/ encoder.  

2. Motor sizing, slot pole count:

To decide what is the best motor for your application you need to take in account many of aspects.

  • You start from the power, speed and torque needed.
  • There are many type of motors good for a car conversion ( DC motors, AC motor, Permanent magnets motors (PMSM), Hybrid PMSM ( less magnet material and increased use of reluctance torque), Switch reluctance motor (no magnets, no clogging torque high efficiency, some disadvantages not high start torque, noise and vibrations )
  • For example BMW i3 has a hybrid design between PMSM and switch reluctance motor, by still using some magnets, they where able to create one of the best electric motors on the market.
  •  Higher RPM motors native offer higher power density, because for higher speed you do not need in increase the size of the motor, only for the torque and since the power of a motor is torque multiplied by speed you gain power easy in this way.  Mechanical power at the motor shaft  equation : P[W]=Speed [RPM] * Torque [Nm] / 9.55
  • If a motor has 65kw of mechanical output power the electrical power needed is bigger because of the efficiency. For a car a 60-65kW is enough to have good acceleration.
  • I decided to use 60 slots and 10 poles because this combination is offering 5 symmetries, and high winding factor. 0.966), if you use 12 poles then the frequency becomes to high and the motor eddy currents losses become to high, GM is using the same slot pole combination Chevrolet Volt, also many other producers.
  • We can say that for a higher torque we need more magnets, but also keep the frequency lower than 400-500hz, because higher magnets count will create higher frequency.
  • Motor Frequency calculator : f[hz]= Pole count (magnets nr.) x RPM / 120 Example: this motor has 10 magnets and 7000rpm then f=10×7000/120 = 583Hz. 
  • For this frequency is imperative to use high frequency lamination in the stator like NO-20 or equivalent. Thinner lamination will offer lower eddy currents losses. The thickness for this frequency should not be higher than 0.3mm
3. Choosing the Materials: 
  • Even if in the last 50 years the PMSM motor theory remained basically unchanged, the big improvement was in the materials area, especially in the magnets.
    This days the magnets are very powerful, and this allowed for very high motor densities to become a reality. Also with the use of thinner and thinner silicon steel laminations the frequency of the motors was increased 10 times versus of a conventional AC motor that runs at 60 or 50hz, this resulting in very high RPM and many pole pairs. For example regarding this motor a NO-02 material in the stator (0.2mm thickness) compared with M235-35A materials witch is 0.35mm thick, will give an improvement of 0.5% in efficiency, which is quite a lot can mean 400w of less power dissipation.
  • Neodymium Iron Boron is an alloy made mainly from a combination of Neodymium, Iron, Boron, Cobalt and of other transition metals and with varying levels of Dysprosium and Praseodymium. The exact chemical composition within NdFeB depends on the grade of the NdFeB magnet. Dysprosium and Praseodymium are added to improve the Hci (Intrinsic coercivity) of the “Neo” magnets.
  • Stronger magnets produce more torque so more power in the end. I decided to have N42UH magnets with phosphate coating, Stronger than N42 can not sustain high temperature operation so i stop at N42.

4. Motor topology, calculations and simulations: 

  • To be able to calculate and determine all the parameters of the motor a simulation software is needed, they are extremely expensive unfortunately.
  • Even with a tool to simulate the motor, you still  need to know and understand all the parameters, to determine best motor topology for certain application, so is almost pointless for somebody to try the software if there is no university background for electric motor like me for example.
  • The software can determine many parameters, but it can determine them well if you feed with the correct data, correct materials and correct assumptions.
  • Underneath is the 60 slot and 10 pole model with transparent core to be able to visualize the coils and magnets.
  • Mechanical analysis is done in a separate program to evaluate the centrifugal forces that tend to throw the magnets outside the rotor.

This test is very important because you want to make sure the magnets will not fly outside, but you also want to have them as close to the exterior with bracket as thin as possible.

My test bench setup

Skewed magnet representation: 

Stress analysis. A force of 2700N was applied to each magnet in outer direction to simulate the centrifugal force produce by the rotor rotation at 7000 RPM. The limit force for the material is about 250 Mega Pascal. So we are way under the limit.

Motor simulated at different parameters and loads


Main Electrical characteristics:

  • Peak Power …………………………………….130Kw, 1min.
  • Nominal Power(S1 continuous) :……… 65 kW
  • Max speed: ………………………………. 8000 RPM
  • Supply DC bus Voltage: ………………… 280Vdc
  • Supply DC bus Voltage: ………………… 280Vdc
  • Peak Torque :………………………………………… 200 Nm
  • Very low cogging torque (Zero current)………….. 2,5Nm (lower than 1% of the motor torque)
  • Ac Supply……………………………………. 151 VAC
  • Turns: 2, parallel paths: 4

  Mechanical Characteristics:

External diameter 292mm

length : 190mm

Weight ~ 36kg

The video represents the flux polarity, is displayed radially. As we can see the field is moving form coil to coil in front of the magnets.

The motor has big peak capability ~2x and enough iron not to saturate the core. At continuous operation the flux in the tooth and back stator is not higher than 1,5T

    Winding distribution and parameters:

65kW Permanent magnet synchronous motor

  • Connection Type : Star
  • Number of parallel paths: 4
  • Number of turns: 4
  • Wire diameter 0.61mm
  • Number of strands in hand 23

Calculations: Conductor area is 6.75mm2 per each path. Using 0.61mm diameter wire we end up with 23wires in parralell.
Since we have 4 parallel paths total conductor area will be 6.752 x 4 = 27mm2 resulting a current density of 9,63Amp RMS/mm2. With a water jacket around the motor to cool down, the motor temperature will be about 90 degree celsius from the simulations.

The efficiency map in Non linear mode took 5 hours to simulate with core i7 7700 processor. In practice we expect some variations due to the materials, and motor construction tolerances.



Rotor balance evaluation
  1. Looks like an interesting project.

    If you need any volunteer help fabricating some parts, contact me, I have a well equipped CNC machine shop.

    • iulian berca says:

      Thank you for your support, actually i am looking for somebody to make or help with the parts.


      • Sounds like fun.

        My equipment list is:

        2 CNCs largest one has 762mm travel, very accurate Mori Seiki.
        A Webb lathe
        OD Grinder
        Surface Grinder
        TIG Welder
        Sunnen hone

        I can help with making prototypes but don’t usually do any production.

        You can send me any CAD files or drawings with information about materials, tolerances and finishes etc. I have never made an electric motor but I am interested in the subject.
        I have built an electric bike (hub motor).
        Would like to build a very powerful electric motorcycle some day.

        • iulian207 says:


          Very nice, i will soon finish the cad drawings and i will attach them, or everyone to download, a cnc lathe with live tool was nice if you had it.
          But we will see what we can do.


      • Rupert Veitch says:

        How much are you selling these motors(65kw – 130kw version) for?

  2. Brook Drumm says:


    I am Brook. I own an open source 3d printer manufacturing company – Printrbot.

    I am designing an open source electric vehicle that is unique in a few interesting ways. To be truly open source, I have found an open source motor controller that can power up to 200kW!

    Now I am looking for an open source motor. The car is really a one seater around-town NEV. I live in Lincoln, California and there are many NEVs- I own one. Since I have access to tools, machinists, electrical engineers, etc… I’d love to see how I can help you.

    I must say, this looks like a perfect match for crowdfunding… in 2022, I raised $831K for my 3d printer- it can work.

    Anyway, feel free to reach out if I can help in any way.


    • Berca Iulian says:


      I`m interested in a crowdfunding, we can work together to make the best motor on the market but also with a very low price.

      Please write me an e-mail on my private email address, found at my website top in About menu.


  3. Jack Hann says:

    Very interesting job.
    If i want to order your motor for my drone, the price includes controller and inverter, or not?
    please write a email to me with the prices to your 35 45 65kw motors, thank you very much.
    I’m very interesting at your project, if it is possible, i also want to be part of your group for crowdfunding and marketing. I live in Germany, not too far.
    Liebe grüße.

    • JUSTIN GREEN says:

      Hi Julian,
      I’ve been watching your research and development for months now and I’m curious to see your CAD files for your 65 kw motor to help me learn how to make efficient BLDC motors. Thank you so much for sharing. It will inspire others like us to innovate and push technology forward. Do you have any idea when you will post the design files?

  4. Karms says:

    Hi, when your motor will be open source and when will you make another post?

  5. Berca Iulian says:

    I should finish soon, it within a week let`s say. Is depending on my available time.

  6. Miguel Camus says:

    Hello mate! What about halbach configuration for the rotor? It seems to be the last tendency!

    • Berca Iulian says:

      hi, Thank you for your suggestion, i`m well aware about callback array, but in this motor is not applicable.


  7. Olivier says:

    Hi Iulian,
    Very interesting project.
    If possible interested to be part of your crowdfunding group.
    One question, did you think it possible to create a 80kW brushless motor working at 560 rpm normal speed. By this way i cannot use reducer ….

  8. Soren Saket says:

    I’m really interested in making my own motors and this has confirmed to me that it’s doable. The problem is that I don’t have an electrical engineering degree (yet), and I can’t find that much useful information on the internet. I would love if you could make some in depth video/text tutorials on the process of creating a motor. Would help me and others out a lot.

  9. Tom W says:


    I would be really interested in using one of these units to build an electric motorcycle.

    Will you be sharing all the details to build one yourself, or selling the motor / kit?

  10. Nguyen Dang Trinh says:

    Hi my Colleague,
    I am Trinh From Praxis Viet nam. Our colleague, Khank gave me your web, and i am impressive with you provide.
    When i was in Holland in 2016. I didnt meet you.
    Nice to see you.

  11. Nish says:

    Which software did you use to get the simulated specification sheet and FEA?

  12. Alberto says:

    Hi, great open source project!

    Please, can you an assembly file or the size of the parts (magnets size angle and position, air gap, …)?

    Thank you so much

  13. Sill says:

    very interesting

    I have a question regarding stator insulation. what did you use to insulate windings form stator.
    By watching your ohter videos, I have noticed that there is something in between yet I have no idea what is the name of this material!

  14. Gaurav Amberkar says:

    I have some questions and I request you to answer.

    1. What software you used for modeling PMDC. I am having difficulty in JMAG. The weight is quiet alot I am getting in evaluation in JMAG. any other software recommendation?

    2. what material to use for rotor stamps.

    3. How to choose right input voltage and current for ev motor. Inguess 500 Volts would be sufficient to get my motor running with continuous power of 110 kw.

  15. Erick says:

    Hi julian i have a question, which magnetic simulation software did you used ?

  16. Caleb says:

    Thanks Julian!

    Will you be releasing the STEP files or just these PDFs?
    I look forward to making a motor and testing it out!

  17. Giovanni says:

    Hello to everyone,

    where can I buy the sheets for rotor and stator? Someone can suggest me a supplier?

    Thank you!!!

  18. Noah Pravecek says:

    Can you post the motorcad files for this motor? I’m trying to change up some parts of it myself and would like to be able to motify it in MotorCad if it’s possible.

  19. Alberto Cesare Barbon says:

    Hi Iulian,

    I realized a little piece of the stator and 3d printed that to try to do two/three wind tests.
    I can’t wind more than three turn with 23 conductors in parallel.

    Be careful, thanks however for your support.


  20. Caleb says:

    The STEP file is in the PDF document and can be extracted.

  21. John Russull says:

    Where can I get laminations laser cut ?
    I live in Cambodia and laser cutting here only works on ( non-magnetic ) stainless steel – with transformer lamination steel it does not cut cleanly. It is very tedious punching out laminations by hand !
    I would like to email a CAD file and receive cut laminations by post ???
    I only need small quantities for now.

  22. Tõnn says:

    Hello, your introduction says 3 slices, but the final design seems to say 2, did that change during the development of the motor and if so, then may I ask why?

  23. Erick Towet says:

    I am interested in the drawings of the motor and stator . trying learn to build one for my drone

  24. Rodrigo says:

    Hello Iulian, Great project! Congratulations.
    Is the STEP file available for download?

    Thank you very much

  25. Jeremiah Gibbs says:

    Hey iulian Thank you for the amazing content on your website and youtube. Have you given any thoughts to publishing a step by step instruction book on all the processes to creating a specific motor with matching controller. You have already shown a wealth of knowledge and I’d personally be very interested in a $20-$30 book you’d produce. Thanks again

  26. Thales Maia says:

    Nice project! Which softwares did you use for field calculation and mechanical analysis? Which process do you use to cut the electrical steel?

  27. I can make the casing for this motor.
    To be cost effective, it would probably be best to cast it in aluminum.

    If you can send me whatever design you have for the housing (it does not need to be designed for casting), I will make a casting design and foundry pattern to cast it.

    Now is a good time for this since I am on vacation and working in the shop for fun.

    I can make a pattern, machining fixtures and machining programs for this in about 1 week.

  28. Anonymous says:

    Question. I am in America and would like to find a supplier of silicon steel for a motor, where would I like for such a supplier of such steel?

  29. Adrien says:

    It’s a very nice project ? Congratulations
    I would like to know how I can obtain your plan for a prototype and if I can ?
    I have some milling machine and lathe and I would like make a fablab.

    It’s not ready now but when it will be okay, i will make you some parts with great pleasure ?.

    Best Regards

  30. Igor says:

    Hello, Iulian!
    It’s a very nice project!
    Where I can see drawings and 3D cad files, and how can i buy the stator rotor magnets kit?
    With best regards,

  31. Hello,

    I am returning to New Zealand soon.

    DO you need someone to represent you in Austrlaia and New Zealand?



  32. Daniel says:

    I’m interested in following along and building a motor myself. I’m not an engineer so I only just understand the theory’s behind you open source motor design. I have a question about scale. If I required a bigger motor for a commercial vehicle, would you use multiple motors of the same design or scale up your design to a bigger motor?

    • Alexis says:


      You can’t scale up a motor and expect the same efficiency. Most of the geometry optimized for physical laws which won’t be directly proportional with the size.
      But for electric vehicles, it’s usually easier to use several “small” motors than one big. (tesla do this)

  33. Erick Towet says:

    could you take a picture of the back of the prototype , i just wanted to see how the mount looks like

  34. amir Ibrahim says:

    Hello Iulian , amazing stuff , have you heard about the QEG ? is it possible to build the Coil

    or a complete kit

  35. amir Ibrahim says:

    Hi . another question have you tried to couple a dc motor to a generator and feed it back to the motor , like who they claim they can do that Free Energy ?

    Ron Brandt QEG generator which was producing 30kV with 3 amp

  36. Jeremie says:

    Hey Julian, what an amazing project ? Any fresh and good news about it ?
    I’m designing Open Source machine tools (a vertical mill/VMC to start with) and Open Source motors are the MISSING LINK ! I would love to have my machine(s) powered by your design, driven by STMBLs or Odrives, and controled by LinuxCNC…
    Please keep us informed of the project status and how we may support it.
    BTW, I’m in France and work in a machine shop with Wire EDM cutter, 5 axis VMC and lathe so let me know if we can be of any use…

    Very best

  37. Greg Adaka says:

    Hi Iulian,
    This looks like such a fantastic project. I’d like to pre-order the 130kw BLDC motor. How do I pre-order?


  38. Manuel Di Frangia says:

    Hi Iulian,

    Is the motor going to be produced? I’d like to pre-order one

  39. iulian berca says:

    As soon as i get the funding to make a stamp for the lamination.

  40. Tad C Johnson says:

    How is it going on the DXF drawings? I would like to replicate a small version for a motorcycle conversion. Nice work by the way!

  41. stephane says:

    Hi julian
    great project!! Can i have cad files please?

  42. shin hyun su says:

    Hi Julian

    have questions.

    Did you wind the coil yourself?

  43. Sylvain Rochette says:

    Where are the file for making this motor, like list of material, cad file to we can find someone to make the pieces etc.., i am interested making one for a personal EV project.

    If the file are available where are they lol


    • Tad Johnson says:

      We would have to make the drawings for ourselves it looks like. Not a big deal if we have the basic lamination shape and size. Tell me when to get started = )

    • iulian207 says:

      The design is not open source.

      • Sergio says:

        Hi Iulian, how much is your project? (PDF and STEP files)

        Please, send me an email…

        • Sergio says:

          Hi Iulian!

          I’m from Brazil and I’d like to build your motor for application of my final course project in electrical engineer. I am designing a turbobomb with electrical motor for rocket concept… I would like to use your project… mail me, please!



  44. Alan says:

    Would you please share how much copper in kilos goes for such stator?

  45. Claudiu says:

    Man, awesome work! However I believe that the next electric car may have the power decentralized. I am working on a prototype using four motors one in each wheel. Harder to program more room to maneuver :). Love your smaller motor for the application. Amazing performance bro! Hope you keep pushing as I’ll keep an eye on it.


  46. Adam Toth says:

    Dear Iulian,

    We’re working on an electric AC Cobra. We are looking for motors for this. First of all, I would like to ask what is the current status of the development with the 130 Kw motor?

    Thank you in advance.

    Adam Toth

  47. P says:

    Where can i place order of the motor.

  48. db023 says:

    Hello. Do you provide the design for the DIY community (non-profit under signed agreement)?

    • iulian207 says:

      I did this at the beginning and my suppliers where flooded with my design requests, modified in the wrong way. Then i stopped posting it online. The core will be probably on sale separately.

  49. Giovanni Pietro Carnovale says:

    How do I buy the design of this Motor?

  50. Dasnoy-Sumell Sébastien says:

    Hi Iulian,

    Awesome work ! I’m really impressed by the evolution of your motors since the 45kW BLDC motor (the first time I saw your blog).

    Is there a way to buy a kit for a motor from you (machined housing, water-cut stator and rotor slices, bearings…) ? I’m looking for 4 identical ~100kW motors, but off the shelf motors are way out of my budget.

    More generally, I would be interested to know how expensive your motors are to produce (not counting your time in there).



  51. Brian Stott says:

    Hi Iulian,

    Are you in production with the 130KW motor? Where are specs and pricing? Can you post a link in comments?

  52. Kawakami says:

    Dear Mr. Iulian

    Are you selling this motor ?

    I have been very much interested as a generator for my big drone .

  53. Ian Kelly-Morgan says:

    Hi Julian,

    This is incredible work.

    Regarding your simulated efficiency map, I am curious about your thoughts on the losses at very low RPM. Of course, efficiency is defined as power out / power in, and there is considerable current draw at low torque to create the forces. The actual power output is also low, as power = torque * velocity. But are the energy losses due to heating or just energy stored in the fields?

    The real question I am looking to answer is how much of the energy from an acceleration cycle is theoretically recoverable during deceleration without considering drivetrain losses?

    Many thanks in advance,

  54. Hi Julian

    We would be very intrested to use this motor in a project that we are looking at is this motor available to buy and can the pole pairs be increased ?

    Kind Regards

  55. Khan says:

    This post is written under the tag open source, are you planning to release the source files?
    Warm Regards!

  56. Denis Kolb says:

    Looking for a supplier. 417-438-8706

  57. Praveen t says:

    Hi iam Praveen from INDIA.
    Here we are the startup making electric vehicles, for that we searching for motors and controllers ,
    Once we see your product we are admired and wow, about the build quality.

    In that aspect can you give you product , in quantity about 100, or if you were comfortable with giving your designs at negotiable amount.


  58. Antonijo Kovacevic says:

    Please, could you let me know the status of production.
    Is it possible to buy a motor?

    Best regards,

  59. query says:

    I would like to ask if you would be willing to sell us your 130kW engine and for how much ?
    Alternatively what would the lincense cost to produce it ?

  60. Nick Outram says:

    Hi, I think there is a huge demand for lightweight ‘drone’ motors in the 10kw-50kw class and air cooled (outrunner style seems popular). Freearchhobby sells these but they seem to be out of stock a lot!
    Have you looked into advantages of Axial Flux design?
    Great Projects -thx for posting everything, fun to read what others are up to.

  61. RC airplane says:

    Please, could you let me know the status of production.
    Is it possible to buy a motor?

    Best regards,

  62. Ashith Prajwal says:

    Hey iulian , is this motor still in production and available for purchase?

  63. Manos says:

    I need for an experimental project of a catamaran with electric propulsion two of your 65kw nominal power Motors with controllers.

    are you able to provide them?