limiting the current flow through a BLDC motor winding when rotor is blocked.

Projects Programming
2 
    if ((millis() - rotor_block) >= 1) //Keep the current flow for 3 milliseconds.
    {
      rotor_block -= 1;
      if (!rotor_block)
      {
        rotor_block = 30;

When rotor_block is set to 30 your 'if' means "has it been more than 31 milliseconds since the sketch started?" I don't think that is what you are trying to do. You should record the value of millis() when the timer starts and compare (millis() - startTime) to the interval length to see if the interval has expired. If you want the timer to be something you can turn on and off:

 . static unsigned long startTime = 0;

  if (startTime != 0 && (millis() - startTime) >= interval)
  {
    // This gets executed 'interval' milliseconds after startTime is set to millis()
    startTime = 0;  // Turn off timer.
  }

Maybe you want something like this:

 . static unsigned long rotorBlockStartTime = 0;
  const unsigned rotorBlockInterval = 30;

  if (rotorBlockStartTime != 0 && (millis() - rotorBlockStartTime) >= rotorBlockInterval)
  {
    // This gets executed 'rotorBlockInterval' milliseconds after rotorBlockStartTime is set to millis()
    rotorBlockStartTime = 0;  // Turn off timer.
  }
.
.
.
  rotorBlockStartTime = millis();  // Block rotor for rotorBlockInterval