You are here

Maytech VESC duty cycle & PID control problems

2 posts / 0 new
Last post
subodh.malgonde
Offline
Last seen: 2 years 3 months ago
Joined: 2018-09-18 07:28
Posts: 8
Maytech VESC duty cycle & PID control problems

I am using the VESC Tool to configure my Maytech VESC. Hardware 4.12 and firmware 3.40. I am using a 3S LiPo battery. The motor is Velineon 3500, used in 1/10th scale Traxxas RC car.

These are my BLDC Sensorless settings:

  • Startup boost: 0.1
  • Cycle Integrator Limit: 39.5
  • Min ERPM: 200
  • Min ERPM Integrator: 800
  • BEMF Coupling: 450

The 'BEMF coupling' and 'Cycle Integrator Limit' values were determined using "Detect BLDC Parameters" functionality of the VESC tool.

When I apply a duty cycle of 0.2 the motor jerks back and forth and does not rotate smoothly. Setting the BEMF coupling to 100 fixes this issue and the motor runs at about 9000 ERPM with a duty cycle of 0.2. But then why does the VESC tool detect the same parameter as 450? What is the consequence of setting a low BEMF?

Now I try PID control with BEMF Coupling set to 100, Ki = 0.0001 and Kp = Kd = 0. When I set the speed to 3000 ERPM the motor jerks back and forth and does not rotate smoothly. The current also peaks to the max limit that I have set (30 A). What could be wrong with the VESC configuration?

subodh.malgonde
Offline
Last seen: 2 years 3 months ago
Joined: 2018-09-18 07:28
Posts: 8

I used the FOC mode instead of the Brushless mode and it worked in the first go. The PID gains could be tuned easily and now the motor startup is very smooth. 

I came across some posts on this forum and the ESK8 forum, which recommended not using FOC mode with Maytech VESCs. I decided to give it a go since the brushless mode simply wasn't working for me. Hope it won't damage my VESC.