Universal ESC Circuit for BLDC and Alternator motors

In this post I have explained a universal ESC circuit or an electronic speed controller circuit which can be universally applied for controlling any type 3 phase BLDC or even an alternator 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 I have explained 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.

Three Phase Generator Circuits

Since a BLDC motor requires a 3 phase signal, the first thing that needs to be designed is a 3-phase generator 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 alternator 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:

• IRS2330(D) (2.5µs deadtime)
• IRS2332(D) (0.8µs deadtime)

In our universal ESC circuit we will use the IRS2330 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 alternator driver 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 MOSFET driver IC IRS2330.

The IC IRS2330 hence 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.