BLDC Motor Notes

How to debug new Brushless DC motor not working?

Ask QuestionAsked 18 days agoActive todayViewed 23 times2This question was migrated from Electrical Engineering Stack Exchange because it can be answered on Home Improvement Stack Exchange. Migrated 7 hours ago.

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I’m building an autonomous boat, for which I so far used this brushless motor powered by this drone ESC (both pictured above).

I now want to start using a more efficient motor, so I bought the 12V 4000RPM version of this motor (pictured below this message). I removed the old motor and connected up the new one. It gives the same beeping sounds when I calibrate it with the software, but after that, it doesn’t move at all. I use the exact same code and ESC setup with the new and the old motor. I tried the Go code I used for the other motor, and also tried some other example Python code with which the other motor also works great.

The wiring info of the new motor has 6 wires, as compared to the only 3 of the old motor. The wiring diagram of the new motor looks like this:

enter image description here

I connected it as follows:

  • the + of the ESC => red wire of the motor
  • the – of the ESC => black and the blue wire of the motor
  • the PWM signal of the ESC => yellow wire of the motor

I’m not sure if this is the correct way, but it’s the best I could come up with. I’m not sure whther the -/minus of the ESC should also be connected to the blue wire, so I tried it both connected and disconnected. But none of my attempts make the motor spin.

And from here I’m kinda lost. Seeing that I’m more of a software guy than an electronics guy I don’t really know how to debug such a hardware problem.

Could anybody give me some pointers on what the problem might be, and more importantly, how you go about debugging something like this? All tips are welcome!

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untaggedshareedit  follow  flag asked Aug 4 at 14:36kramer65

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1 Answer



How to troubleshoot a BLDC motor?

Note: This question was migrated from Electrical Engineering Stack Exchange because it can be answered on Home Improvement Stack Exchange. Migrated 2020aug23hkt1221 ago.

bldc motor


Part A – TLDR

All my life I have been playing with toy DC motors, and I know them very well. However I have almost zero knowledge and experience on BLDC motors. I know that drones use BLDC motors, but actually I never owned any RC toys in my life, not to mention RC drones.

I also know quite a lot about 5V/12V regulated power supplies for toy motors, but I don’t know what is ESC, and I have never seen the real ESC thing in my life.

I need to introduce my sub newbie knowledge and experience on BLDC motor because I must warn the experienced RC guys that I am ignorant in RC, so bear with me talking stupid RC stuff. RC Ninjas can skip the following parts basic parts and start with the real BLDC thing.

But I would appreciate it very much if anyone can point out my misunderstanding on RC, ESC, and BLDC, so I can make corrections ASAP, before letting EE SE losing too much face, …

Part B – Googling and Wikiing on BLDC Motors

So I wikied and sursprisingly found that BLDC is much more complicated than the stupid DC motor, because inside it there is a switching power supply providing AC current, and most amazingly is that there is a control loop driver controlling the speed and torque of the motor.

This is indeed exciting, because I am starting to learn some control engineering theory and practice. Now I can boast to my bad friends that I am not just an plain vanilla EE hobbyist, but also a computing and control hobbyist. So my bad Anono friends should from now on respect me much more than I deserve, …

Part C – BLDC Motor, A case study

I found that the OP’s BLDC motor is a bit expensive, and also high speed, high torque (5,000rpm!). I think this scary 5,000 rpm motor is too dangerous for me newbie to handle. So I searched AliExpress for a poor hobbyist affordable (US$20), and also newbie save gear model with a speed range of 10 rpm to 500 rpm. The most important thing is that the both the OP’s expensive and my cheap motors are using the same BLDC standard of 6 pin colour coded connector.

AliExpress JGB37-3525 37mm Gear BLDC Motor US$20 – Aslong

Amazon JGB37-3525 (12V – 33RPM) 37mm Gearbox BLDC Motor US$22

Both AliExpress and Amazon are selling at the same price of US$20. I think Amazon is recommending the 33rpm model because it is safe for newbies, also the maximum (stall) current is only 0.7A. So it should be safe to use 12V Lipo power bank to do the tests.

bldc current spec

The OP is curious to know what kind of driver is inside the BLDC motor and will the driver clash the ESC. Now I know the built in controller in the BLDC guy is a high class feedback controller, and I guess the ESC guy is as most as clever the toy servo. So I am no more interested to look into the ESC thing (Actually I should pretend not not have heard of ESC, so my bad friends would respect more that I deserve)

Now I am digging deeper into BLDC. I am happy to find from the Amazon that their motor is teardown/hacker/newbie/prototyping/enggrdesign friendly, eg easy to change speed by replacing different speed (or fried, clashed, I mean) gear box.

bldc gear

Another good thing about the motor is that the specification is quite professional, eg with detailed engineer drawing, showing things I am interested, eg, the shaft diameter is 6mm. I used to play with Mabuchi TT130 4WD type motors with a miserably thin/weak 3mm shaft diameter, or bigger motors with 4mm,, 5mm diameter. Now this motor is heavy duty 6mm. So I should now upgrade my motor status from newbie to ninja, and from now talk less to the low tech DC only, non BLDC guys, so not to damage my reputation

The OP is asking how to wire the following connector, to make the motor moving.

 Now let me see if the AliExpress/Amazon BLDC motor is using the same connector.

I first looked at the OP’s connector and found it not identical to the BLDC motor I am study. So I went to check out the other motor, and found the following spec:

jgb37 connector

I very surprisingly found that the reason why there are as many as 6 wires, in two groups:

  1. Motor power = 2 wires,
  2. Encoder = 4 wires, 2 for power, 2 for encoder A, B phase.

What I found interesting is that there are two power wires, but no PWM signal control wire. My first guess is that the motor +ve, -ve power wires when go inside the motor casing, can be switch polarity to select CW and CCW. This is indeed strange, is there a full bridge inside the “controller”. I am as curious as the OP, and I should tear down the controller inside black cylinder, to see what is going on there.

Ah, locking down supper time. Call it a gloomy Sunday. Carry on till tomorrow.

/ to continue, …


(1) How to debug new Brushless DC motor not working? – @kramer65, Home Improvement Stack Exchange, 2020aug04

(2) 38SRZ-S BLDC Motor 12V/24V 2000/3000/4000/5000 rpms with built in drive for DIY US40 – AliExpress

(3) BLDC (Brushless DC) Electric Motor – Wikipedia

(4) AliExpress JGB37-3525 37mm Gear BLDC Motor US$21 – Aslong

(5) Amazon 37mm Diameter Gearbox Low noise Long life High Torque 12v 24v Brushless DC Gear Motor Silent bldc gearmotor JGB37-3525 (12V – 33RPM) US$22

(6) ESC (Electronic Speed Control) – Wikipedia

/ to continue, …


Appendix A – BLDC Motor Wiki Reading Log

(2) BLDC (Brushless DC) Electric Motor – Wikipedia

So I wikied and learnt a lot, and made a reading log, which is a summary of the introduction part of the wiki column.

A BLDC motor, also known as electronically commutated motor, and synchronous DC motors, are synchronous motors powered by DC current via an inverter or switching power supply which produces AC current to drive each phase of the motor via a closed loop controller. The controller provides pulses of current to the motor windings that control the speed and torque of the motor. This control system replaces the commutator (brushes) used in many conventional electric motors.

The construction of a brushless motor system is typically similar to a permanent magnet synchronous motor (PMSM), but can also be a switched reluctance motor, or an induction (asynchronous) motor. They may also use neodymium magnets and be outrunners (the stator is surrounded by the rotor), inrunners (the rotor is surrounded by the stator), or axial (the rotor and stator are flat and parallel).

The advantages of a brushless motor over brushed motors are high power-to-weight ratio, high speed, electronic control, and low maintenance. Brushless motors find applications in such places as computer peripherals (disk drives, printers), hand-held power tools, and vehicles ranging from model aircraft to automobiles, …

End of answershareeditdeleteflagedited just nowanswered 7 hours agotlfong0110122 bronze badges

  • 1This is a random collection of personal anecdotes, not an answer. Please spend some time reading the guidance on what constitutes an answer on an SE site, you’ve developed a bit of a habit of making this sort of off-topic response. – Chris Stratton 3 hours ago 
  • / to continue, … – tlfong01 2 hours ago   

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