u/Sup_Its_Ale

Hi all,

I salvaged the hydraulic unit from an automatic parking barrier: a 36V brushless motor driving a small oil pump that moves two hydraulic cylinders. I want to reuse it for a robotic arm, but the original control board is closed, so I want to replace it with my own PCB.

Situation:

∙	The motor has only 3 phase wires, no hall sensors or encoder.

∙	The only encoder in the system is on the barrier arm, not on the motor.

∙	The pump may have to start under load, with oil already pressurized.

∙	I haven’t measured the current yet. I’ll check what the original board draws and the motor’s winding resistance, and add the numbers.

Constraints:

∙	Low cost.

∙	No ready-made modules or boards: I want to design the PCB myself.

∙	I’ve never made a motor controller at this voltage and power. I’m comfortable with PCB design and firmware, but new to power stages.

What I’d like your advice on:

1.	Which MCU, gate driver and MOSFETs would you pick, and why?

2.	How would you handle motor control and start-up under load?

3.	What are the common mistakes at 36V that I should avoid in layout and protection?

I’ll attach a photo of the original board. Thanks!