25.2. BLDC FOC Control

25.2.1. Overview

The bldc_foc project contains the speed control and position control of DC brushless motors. - Use the FOC (Field Oriented Control) control algorithm - Support both hardware and software current loop implementation - Support dual closed-loop control of speed and position - Support both ABZ encoder and QEI encoder for position detection

25.2.2. Configurations

This program uses the BLM57050-1000 brushless motor of “Leisai Intelligence”, please refer to the Leisai Intelligence website for the specific parameters of the motor.
Board settings refer to the development board documentation Motor Pin related content
- Ensure PWM frequency is set correctly
- Ensure motor pole pairs is set correctly
- Ensure ADC sampling configuration is correct
Peripheral Configuration:
- PWM Configuration:
  
  Use BLDC PWM module
  
  Configure dead time to prevent shoot-through
  
  Configure complementary PWM output
  
  Support three-phase six-channel PWM output
  
  Support PWM synchronized ADC sampling trigger
  
  Use shadow register to update PWM duty cycle
  
  Support PWM fault protection
- ADC Configuration:
  
  Use two ADC modules to sample U-phase and V-phase current respectively
  
  Configure ADC reference voltage
  
  Configure op-amp gain
  
  Configure sampling precision
  
  Configure sampling resolution
  
  Support DMA transfer
  
  Support ADC synchronized sampling
  
  Support ADC trigger source configuration
  
  Support ADC sampling interrupt
- Encoder Configuration:
  
  Support ABZ encoder and QEI encoder
  
  Configure encoder precision
  
  Configure encoder direction
  
  Configure encoder sampling period
  
  Support encoder position counting
  
  Support encoder speed calculation
- Timer Configuration:
  
  Use GPTMR as timer
  
  Configure current loop sampling period
  
  Configure speed loop sampling period
  
  Configure position loop sampling period
  
  Support timer interrupt

25.2.3. Current Loop Time

Hardware current loop will show time zero. The current loop calculation time is around 1us, this time fluctuates depending on the angle and fluctuates in the range of 25%, which is reproduced by performing the following operation:

Turning off the mcl_app_config.h macros except for MCL_EN_LOOP_TIME_COUNT
Compile option flash_xip_release

25.2.4. Running the demo

The motor runs at default speed. The following data can be configured by serial console:

speed float, range +40~-40, unit r/s - Positive value for forward rotation - Negative value for reverse rotation - 0 for stop

pos int, (-4000, +4000) corresponds to (-360, +360) degrees - Positive value for clockwise direction - Negative value for counterclockwise direction

mode bool, 1- Speed mode 0- Position mode

Speed mode
- Enter the correct speed parameters with serial console
- Use PID algorithm for speed control
Position mode
- Set the position of the motor’s shaft, then the motor’s shaft will be locked at the specified position
- Use PID algorithm for position control

loop current tick: 399
Mode selection:
0. Location mode.
1. Speed mode.
Enter mode code:
1
Speed mode, motor run, speed is: 20.000000.
Input speed:
10.5

loop current tick: 535
Speed mode, motor run, speed is: 10.500000.
Input speed:

Warning

After the motor is powered on, it will first perform the “alignment” action. If the motor is disturbed at this time, it will produce a jitter
Pay attention to the current size, when abnormalities occur, please cut off the power at any time
When entering values for speed and position, a line break is required as an end-of-entry flag
For first-time operation, it is recommended to start testing at low speed
In position mode, ensure the motor is not subject to external force interference