Finding BLDC motor for required specification! - Page 1
Forum section: electronics / beginners

author: Swapnil
author_rank: Contributor
timestamp: May 21, 2022, 07:29:09 am
content: Need help finding a BLDC motor for the required specifications:Rated power output - 120WRated input voltage - 24VDC (18-30VDC)Rated speed - 1400 RPMRated torque - 1 to 2 NmMotor Length - 110 to 120mm (with shaft)I have found a lot of Chinese Ebike motors but need some more reliable options.

author: Benta
author_rank: Super Contributor
timestamp: May 22, 2022, 10:16:05 am
content: You have one parameter that could be a show stopper:1400 RPM. I've never seen BLDCs running that slow and at the same deliver significant power.

author: den
author_rank: Contributor
timestamp: May 22, 2022, 07:08:09 pm
content: What meaning do you put in "rated"? If you are looking for max. efficiency or power, than I don't think you find any motor which will suit you. For the speed, KV rating will have to be very low. To get a low KV motor normally gets bigger in diameter, and then normally it has more power. So in your case - either your motor will be hugely oversized in terms of power (x10 and more), but will achieve the needed Watts at this low speed, or you just look for a motor with a reduction gear. The manufacturers where to look: T-Motor, Hacker, KDE, Maxon motors.

author: Swapnil
author_rank: Contributor
timestamp: May 24, 2022, 09:36:14 am
content: Quote from: den on May 22, 2022, 07:08:09 pmTrue, the motor size will be bigger as the given constraint for the motor is around 80mm(diameter of the motor) and 100mm(length of the motor). What type of motor controller will this oversized BLDC require? Is it some kind of ESC or a motor driver like Brushed DC motors?

author: Siwastaja
author_rank: Super Contributor
timestamp: May 24, 2022, 09:47:10 am
content: Quote from: Benta on May 22, 2022, 10:16:05 amI have seen many, 1400rpm isn't low RPM at all, it will work out with moderate pole count like 8 or 10. All hoverboard motors, ebike motors etc. fit this low RPM goal. They are obviously hub motors and OP needs something else and also ruled out Chinese no-name ebike motors as unreliable, which of course makes finding one much more difficult.Maybe look at CNC servo motor market. Good brand products are going to be really expensive and possibly hard to find and buy.But yeah, you are right that the higher the RPM, the better power density. 1400RPM is easy, but obviously the motor will be bigger (with more iron) than one designed to deliver the same power at double the RPM and half the torque.

author: Swapnil
author_rank: Contributor
timestamp: May 25, 2022, 05:07:19 am
content: Quote from: Siwastaja on May 24, 2022, 09:47:10 amSo, what type of motor controllers do such type of bigger BLDC motors require?

author: Siwastaja
author_rank: Super Contributor
timestamp: May 25, 2022, 07:13:07 am
content: Just... the same type. It's just called BLDC controller. Usually comes with FOC algorithm.For cheap Chinese solutions, look at e-bike controllers. For high quality products, you are on your own, I could imagine it's colossally hard to find and buy something like this.I have always designed what I need so I don't know where to buy pre-engineered modules, except Chinese Aliexpress specials.