HALF BRIDGE ESCMay 07th, 2021 | by: ELECTRONOOBS
Category: Electronics Basic Circuits
I hope you all remember my open-source ESC design that I’ve made last year and the other versions as well. That one is based on a full triple bridge of MOSFETs and a back EMF closed loop control. This one here for today tutorial, is based on a half bridge control. Basically, half the amount of MOSFETS and half the complexity. This type of ESC only works with those 4 wired brushless motors, meaning we need the 3 phase A, B and C, but also the common point of the star configuration. In this tutorial I will show you this basic half bridge ESC, what’s the deal with that common point on some brushless motors, the components I will use, make the circuit on a PCB and give it a few tests, and I hope you will learn something new. Please have in mind, this circuit has no feedback and is not even close to the results of the full bridge ESC from my previous videos. I'm showing you this circuit just for learning purposes. So guys, let’s get started.
Below you have the schematic I've used. Is very basic and simple. We have 3 N channel MSOFETs connected to ground. Each one has a diode from its drain back to the battery so the current spike from the motors could have a path to flow through and not damage it. Each MSOFET has a pulldown so it would be turned OFF by default. I also add an AMS1117 regulator for 5V and to control the pulse we could use an Arduino, but since this is a very simple design, we can go with a small ATtiny85. To control the speed, we can use a potentiometer for this example but with a more complex code, we could also control the speed with a PWM input.
I’ve made all the connections on a prototyping PCB starting with the 3 MOFEST. I've then palced the AMS1117 and made sure that with 12V input I have 5V output. Then I can add the ATtiny. The connections are made with some copper wires on the front and on the back. We also have connections with the small resistors and diodes. I've soldered the potentiometer external to the PCB and I'll use this to adjust the speed. I've used screw terminals fot the battery input and the 4 outputs that go to the motor.