I am planning to build a high speed centrifuge.
Does the discharge rate really matter for low speeds of BLDC(around 50%)?
Can I control the current consumption(strictly less than 10A) by the BLDC motor unit with the help of pwm control to the ESC itself without blowing up my SMPS??
BLDC Motor: 1400Kv
ESC: 20A
SMPS: 12V 10A
Best Answer
Yes, it should be safe. However there are a few things to watch out for:-
Unlike a battery, power supplies are poor current sinks. During commutation and PWM the motor generates current spikes which can feed back into the supply and cause the voltage to rise. This effect can be reduced by adding a high capacitance low-esr bypass capacitor across the controller's power input terminals. This will also help to suppress voltage spikes caused by inductance in the power wires.
If the current would exceed 10A at full throttle (100% PWM) then rather than simply lowering the throttle you should either reduce the load or use a lower Kv motor. The reason for this is that motor current is multiplied by the inverse of PWM ratio. For example at 50% PWM an average power supply current of 10A corresponds to 20A at the motor, with even higher peak currents. This current is drawn from the supply 50% of the time (during PWM 'on' time) so peak power supply current could also be 20A or more.
When the motor is accelerating it will draw more current, which might cause the PSU to shut down if it exceeds 10A. To avoid this you should ramp the throttle up slowly so the dynamic torque load is less.
Switch-mode power supplies often have a sensitive current monitor which will shut down the PSU on even brief overloads. This won't cause any harm but is annoying.