Bldc motor controller

Thread Starter

Eartian

Joined Sep 16, 2021
29
Hello everyone, I need a bldc speed controller for a motor which is requires 1.5k watt controller. I needed it for building my college project. I searched the controller online and all of those are costlier. Moreover I will not be using extra features given by them. So can anyone suggest me a speed controller diagram so that I could build myself one. That controller need to control bldc (doesn't have hall sensor) which is rated to run at 48v.
 

MisterBill2

Joined Jan 23, 2018
18,167
What control functions does the application require?? The requirements of the application define what must be provided in any circuit intended to be useful. Otherwise you only have guesses.
Does the application require variable speed control? Does the application require the motor to be reversed? What is the intended power source? AC mains, or DC? What sort of speed control would be required?
The amazon listed controller description was obviously written by one with no technical background and no technical understanding. Aside from the supply voltage and dimensions it offers little useful information.
 

Thread Starter

Eartian

Joined Sep 16, 2021
29
What control functions does the application require?? The requirements of the application define what must be provided in any circuit intended to be useful. Otherwise you only have guesses.
Does the application require variable speed control? Does the application require the motor to be reversed? What is the intended power source? AC mains, or DC? What sort of speed control would be required?
The amazon listed controller description was obviously written by one with no technical background and no technical understanding. Aside from the supply voltage and dimensions it offers little useful information.
No need for reversing, the circuit need to handle 48volt dc, which will be supplied by battery. The circuit needs to handle 1.5k watt power
( because, even though motor is rated 500 watt, it can draw more power in initial conditions). Circuit needs to control the bldc motor speed. Which does not have hall sensor.
 

shortbus

Joined Sep 30, 2009
10,045
I searched the controller online and all of those are costlier. Moreover I will not be using extra features given by them. So can anyone suggest me a speed controller diagram so that I could build myself one.
If your project isn't due for a long way off you may be able to make one that will work. But if needed soon you will be farther ahead to buy one. What today seems expensive will after trying to make one that actually works look inexpensive, Any schematic you will find is just a "suggestion", not something that will work the first time without much troubleshooting.

The big problem with a DIY speed control is your choice of motor. The ones using Hall sensors are easier to make a controller for. The sensor less ones add another level of difficulty to the mix. There is a well known IC that makes a Hall sensor motor much easier to do.

Good luck with your project.
 

Thread Starter

Eartian

Joined Sep 16, 2021
29
Thanks for replying. I don't need it urgently. I have enough time to build one.
But yeah, diy can be more expensive than the available one. So I am thinking of buying one now .
Once again thank you for your suggestion.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
Have you checked out the RC ESC ( Electronic Servo Controllers) ?
They are BLDC sensorless , they require the same simple PWM pulse for RPM control as the RC servo units do.
 

LowQCab

Joined Nov 6, 2012
4,023
They also make very small ESCs, check their Home-Page.
I chose this particular Model-Range-page because over-kill = peace of mind,
and there's no-telling what the actual application conditions might be.
.
.
.
 

MisterBill2

Joined Jan 23, 2018
18,167
No need for reversing, the circuit need to handle 48volt dc, which will be supplied by battery. The circuit needs to handle 1.5k watt power
( because, even though motor is rated 500 watt, it can draw more power in initial conditions). Circuit needs to control the bldc motor speed. Which does not have hall sensor.
Still no answer about speed controlling, what range, how stable, and is it controlled by a feedback signal or a hand control? A 1500 watt motor, or a 500 watt motor being driven with 1500 watts, is in the high-overload range where things can go wrong in a short time. This could be a sprint car that needs traction control, or any of a number of short cycle applications. Do you already have the motor? Or is that also yet to be obtained? Is designing the driver a large part of the project?
If the project does not require this specific type of motor, other types may be easier to create a controller for. Certainly a 500 watt rated motor will not be operating at the 1500 watt level for extended periods of time.
 
Last edited:

shortbus

Joined Sep 30, 2009
10,045
A 1500 watt motor, or a 500 watt motor being driven with 1500 watts, is in the high-overload range where things can go wrong in a short time.
Certainly a 500 watt rated motor will not be operating at the 1500 watt level for extended periods of time.
Do you already have the motor?
Did you read the original post? Why do you think a motor drawing only 500W will be harmed by a controller capable of 1500W? The motor will only use what it needs.

Your going back to the old mrbill, who doesn't read.
 

MisterBill2

Joined Jan 23, 2018
18,167
I made that comment because of what I read, " The circuit needs to handle 1.5k watt power ", which tells me that at times the motor may be driven rather hard. So ye, I did read as I have been following the thread.
And you are back to throwing stones.
 

BobTPH

Joined Jun 5, 2013
8,804
I made that comment because of what I read, " The circuit needs to handle 1.5k watt power ", which tells me that at times the motor may be driven rather hard. So ye, I did read as I have been following the thread.
And you are back to throwing stones.
Apparently you missed this:

The circuit needs to handle 1.5k watt power
( because, even though motor is rated 500 watt, it can draw more power in initial conditions).
He needs the higher rating for inrush current. But that really does not make much sense. A speed controller rated for 500W should be able to handle the inrush for a 500W motor.
 

MisterBill2

Joined Jan 23, 2018
18,167
I did not miss that. What I am thinking is that the unstated application involves over-driving the motor. In a manufacturer's servomotor application class it was explained that driving a motor to the rated "peak" power can be done but there are limits to how long based partly on ambient temperature, and also other factors. Or did I miss some statement about the specific application?
So I am thinking that similar constraints will apply to a BLDC motor. That is the reason that I stated my caution. I am guessing that the stated 500 Watt rating is not a peak power rating, but rather for continual operation steady-state.
I failed to mention all of that previously, hence the stone throwing by others.
 

shortbus

Joined Sep 30, 2009
10,045
What I am thinking is that the unstated application involves over-driving the motor.
Can you explain how supplying a higher potential power is over driving a motor? A motor like all things electronic is only going to draw what is needed from the power supply. Over voltage may be bad(within a certain limit) but actual amps to make the watts is only due to load on the motor.


In a manufacturer's servomotor application class it was explained that driving a motor to the rated "peak" power can be done but there are limits to how long based partly on ambient temperature, and also other factors. Or did I miss some statement about the specific application?
Again the above applies here too. I think you misunderstood what was said in the class. Over loading will harm a motor over time, but not having more watts available.

So I am thinking that similar constraints will apply to a BLDC motor. That is the reason that I stated my caution. I am guessing that the stated 500 Watt rating is not a peak power rating, but rather for continual operation steady-state.
That's why a higher ratted power supply is used.

I failed to mention all of that previously, hence the stone throwing by others.
Why is it when some one questions your answers you call it throwing stones? Would you please explain your thinking? If you give a bad answer they need to be called out. There are no "alternative facts". If your bad answers aren't called out your just making a clone of yourself to the person that asked the question. It may not matter to you but we're not all like you.
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
No need for reversing, the circuit need to handle 48volt dc, which will be supplied by battery. The circuit needs to handle 1.5k watt power
( because, even though motor is rated 500 watt, it can draw more power in initial conditions). Circuit needs to control the bldc motor speed. Which does not have hall sensor.
Can you supply pic of the motor? Have you looked at the RC ESC option?
What reason for the high power requirement at switch-on?
 

MisterBill2

Joined Jan 23, 2018
18,167
When a higher power driver is used, the option of applying more than the ratd power is available, and my reading of the limited description implied that the motor application would require over driving the motor to a higher power level at times. A servo system is different from a fixed resistor in that it is entirely possible, and sometimes done, to command a drive power level at the peak power rating. Those who know what they are doing can get away with overdriving for short times, those who do not understand what the peak power rating is may burn up the motor.
200 milliseconds at 150% rated power to provide the required velocity for an impact test worked because after that was a 15 second power off time that allowed cooling. That was one that I did a few years back. It avoided buying the next size bigger motor.
 
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