Difference between motor reversing BLDC and (FOC trapezoid/center line)5 months, 2 weeks ago | 1 Replies
I know that many members are still confused about the real difference between FOC and BLDC modes in their VESC or any other ESC that performs this kind of commutation. Most people know that FOC mode is much better than BLDC mode, and that’s true. I’m not an electrician personally, just a regular person like all of you, and I’ll show you the difference with the chart below.
BLDC commutator motors
BLDC trapezoidal commutation
Sinusoidal reversal (FOC)
So what these people are talking about is reversing based on a diagram of the motor’s current output. BLDC only switches the phase On and OFF quickly, while the trapezoid and sinusoid do not switch, but modulate the phase.
Because there is no high-current quick switch in FOC mode, the high-pitched sound you usually hear from BLDC commutation is absent entirely.
Logically, since the FOC is adjusting the phase, it can maximize the torque output at any point, since the ABC phases are always charged, and each of them uses only the amount required for each rotor position within the motor.
Logically, since sinusoidal control produces a smooth waveform rather than spikes like BLDC and trapezoid, the peak points of each amplitude are smaller than BLDC mode and/or trapezoid mode. So its top speed is slightly lower.
In the FOC sinusoidal commutation, their operational efficiency does make sense when each ABC phase gets the power they require at any rotor/stator position they have.
Generally speaking, this is my understanding as a beginner. I may be wrong about some things, but the performance factors and the general explanation in the chart are definitely why they are named after each other. I hope other people/members can understand this idea