Universal ESC for BLDC motors

In this post we discuss a universal ESC circuit or an electronic speed controller circuit which can be universally applied for controlling any type 3 phase BLDC motor.

What is an ESC

An ESC or electronic speed controller is an electronic circuit which is normally used for operating and controlling a BLDC 3-phase motor.

BLDC motor stands for brushless DC motor which clearly states that such motors are void of brushes, quite opposite to the brushed type of motors which rely on brushes for commutation.

Due to the absence of brushes BLDC motors are able to operate with maximum efficiency since the absence of brushes relieves it from frictions and other related inefficiency.

However BLDC motors have one major downside, these cannot be operated through a single supply like the other brushed motors, instead a BLDC motor requires a 3-phase driver for operating them.

Despite of this technical complexity, BLDC motors become highly preferable compared to their brushed counterpart, because BLDC motors are extremely efficient in terms power consumption and virtually no wear and tear issues.

This is why BLDC motors are today used in electric vehicles, windmills, airplanes, quad copters, and most motor related equipment.

As discussed above operating a BLDC motor looks quite complex, and if you try to look for a driver or an electronic speed controller circuit for BLDC motors you would probably come across circuits which are too complex using MCUs, or employ hard to find components.

In this post we will learn how to make a simple and effective ESC circuit which may be universally applied to operate most BLDC motors through some minor modifications.

Once you learn the details of the circuit, you could use it to build electric vehicles, quad copters, robots, automatic gates, vacuum cleaner and any motor operated product with maximum efficiency.

Since a BLDC motor requires a 3 phase signal, the first thing that needs to be designed is a 3-phase generated circuit.

The following circuits show how this can be made using a handful of operating parts.The first one uses opamps while the second one makes use of just a few BJTs.

Simple 3 phase Generators

The 3-phase signal output needs to be integrated with a 3-phase mosfet driver circuit for enabling the motor operation.

Therefore the second important element is the 3 phase driver circuit, which is supposed to respond to the above 3 phase generator circuit for operating the connected BLDC motor.

For a 3 phase driver, you could employ any standard 3-phase driver IC, such as a A4915, 6EDL04I06NT, or our old IRS233 IC

In our universal ESC circuit we will use the IRS233 and see how this can be configured for the intended electronic speed control and implemented for most BLDC motors. The following image shows the entire circuit of the proposed ESC design.

The ESC Schematic

The presented ESC circuit looks pretty straightforward and does not seem to employ any complex stages.

The 3 phase signals acquired from the 3 phase generator circuits is applied to the inputs of the NOT gates shown at the top left of the above diagram.

These 3 phase signals are converted into the required Hin, and Lin inputs for the 3 phase mosfer driver IC IRS233.

The IC IRS233 hen process these signals to operate the connected BLDC motor with the correct phase and torque via the associated driver mosfets or IGBTs.

We can also see an IC 555 based PWM stage. This stage is configured with the low side mosfets or IGBTs, for chopping their gate triggers into appropriate sections.

This gate chopping forces the devices to operate at a rate determined by these chopping PWM duty cycle rate. Wider duty cycles enables the motor to rotate faster and narrower duty cycle allows the motor to slow down proportionately.

The PWM rate is controlled through the IC 555 through the indicated PWM pot.

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Unknown said…
is this for a sensor less motor?
Swagatam said…
both types can be used
Keith Hebert said…
Thank you for the response. how about forward and reverse directions. How can this be accomplished?
Keith Hebert said…
Not sure my last question was posted. Thank you for your answer I really appreciate it. I have another, how can reversing be added to this example?
Swagatam said…
forward reverse facility is not provided in the IC, however I think it can be implemented by reversing the 3-phase signal input's logic sequence.
Keith Hebert said…
Thank you. I was looking at that as an option.
Mac Wilkey said…
I had same question on another post today. Will consider swapping two of the hall inputs but seems like hall inputs will track motor direction. May just need to get motor rolling using this approach then switch to hall sensors
Swagatam said…
OK, you can try that...
Mthokozisi Ndlovu said…
Thank you Mr Swagatam. I'd like to know the value of the 6 MOSFETs used for the bridge and also the value of the diodes. I need to construct an ESC for a project that I'm on. I've converted a car alternator to a hybrid bldc motor powered through an ESC for RC hobbies. Unfortunately the motor doesn't have enough torque as I'd like it to be. I was wondering if this circuit will be powerful enough to run the motor under load.
Thank you, awaiting your response.
Swag said…
Thanks Mthokozisi, the mosfets can be as per the user's choice, depending on how much power the output load may be rated at. You can use any suitable ones which may be on par with the rating of the motor. It is better to use IGBTs instead of mosfets for better efficiency.
This circuit can be upgraded for any motor, simply by upgrading the IGBTs accordingly.
Rishee Sharma said…
Hi Swagatam, I'm trying to make a controller for 250W bldc motor. What should be the configuration for it? Can you please get in touch on email?
Swag said…
Hi Rishee, the configuration in the above article is the best configuration according to me, because it does not rely on any special ICs.

You can replace the full-bridge IC with any other variant, and use the other mentioned stages with it in the same format and achieve the required results.

You can feel free to discuss through comments, as this will help the other readers also to learn about your experience in the field.
Mthokozisi Ndlovu said…
Gooday. Thank you Sir again for your response, your work is simply priceless. For my project I have a sensorless motor(no Hall sensors), but I can't find the chip for the sensorless esc https://homemade-circuits.com/2017/08/high-current-sensorless-bldc-motor.html
I need to know if the circuit for the universal esc can be used on sensorless motors and if yes, how does one configure the NOT gates inputs as there are no Hall sensors for the NOT gates to work with. My kind of motor has only three stator windings connected in delta.
Swag said…
You are welcome Mthokozisi,

the universal ESC can be used for driving any BLDC motor or any 3-phase motor, regardless of whether it has Hall effect sensors or not.

This circuit utilizes an external 3 phase generator for signalling the ESC through the NOT gates to operate the motor with a 3-phase 120 degree shift signals, which is the standard value for driving all 3-phase motors, therefore this circuit dos not depend on any sensor and is able to independently drive any 3-phase motor.

you can simply connect the 3 wires of the motor with the outputs from the IGbTs or mosfets for enabling the operation.
Mthokozisi Ndlovu said…
Goodday Sir. I'd like to say thank you again and I guess I cannever say it enough to amount to the kind of work that you do helping electronics hobbyist across the globe. This circuit seems to be the very thing I've been looking for. I guess my case has been settled. I'll let you know the outcome after I've built the ESC. Thank you again.
Swag said…
You are most welcome Mthokozisi, wish you all the best!!
Hello Sir Mr Swagatam. Please clarify this please; for the NOT gates, does one just use one input terminal and corresponding output, also does the NOT gates need to be powered up(Vcc & Vss)?

Best regards.
Swag said…
Hi Mthokozisi, all ICs which have Vcc/Vss pins will need to be powered through an external power supply across these pinous, otherwise the IC will not respond. so yes the 4049 will also need an external DC across these relevant pinouts

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