Archived: the OG noob question thread! 😀

[professor_shartsis]

@Superflim

I read somewhere that motors run most efficient when there the load is around 75%.

What do they exactly mean by this? Do they mean motor amps? So for a 80 amps max motor if you put it at 60 amps it runs most efficient?

@b264

That’s a question for @professor_shartsis

Efficiency Control Mode

To prove the algorithm works suppose we have a motor which is: 190kv At the present moment the motor is turning: 1000rpm We can calculate the voltage the motor is generating (back emf voltage) from: 1000rpm / 190kv = 5.26v bemf Suppose I am accelerating and want instantaneous 85% electrical to mechanical conversion efficiency, what voltage should I apply to the motor? 5.26v bemf / 85% = 6.18v pwm effective voltage What is the motor current (assume motor is 0.05ohm)? (6.18v - 5.26v) / 0.…

You can calculate the motor current in BLDC mode via:

(V_voltage_pulse_width_modulated - V_back_emf_voltage) / R_resistance_winding_ohms = I_motor current

Through a quirk of physics:

V_back_emf_voltage / V_voltage_pulse_width_modulated = E_electrical_to_mechanical_conversion_efficiency_instantaneous_%