need support for inrush current of BLDC motor
Hi @Sravan , welcome to SimpleFOC!
Can you explain a bit more what you are looking for?
Is your setup using current sensing? What driver are you using, and does it have protections?
basically we are using the bldc motor for drone application. In normal generally some inrush current will be there while starting of motror. This inrush will be basically 5 to 10 times of ratted current. So, this current should be controlled so it will be helpful in design of MOSFETs.
So here I need to know the methods to control this current. one I know is NTC Thermistor.
need to know other methods.
Have you tried using the SimpleFOC library yet to control your motor?
Does your driver have current sensing?
In field oriented control the current will be controlled by the algorithm, also at startup. On a well tuned system, the current consumption will be only what is needed for the torque generated.
So especially on a drone setup where the only load on the motor is the propeller, which won’t have any real resistance at zero or very low speeds, I would expect the starting current to be quite moderate - there’s only the internal friction to overcome, really?
Of course the system parameters have to be tuned right, and the whole system bandwidth on the current control has to be sufficient to detect and limit the current rising too high…
@Sravan ,
Is your drone design used in military / dual use applications?
@runger, his drones aren’t using SimpleFOC, he is asking a generic design question. Drones cannot use the current SimpleFOC codebase due to a number of reasons, I tried and failed.
You need mosfets 10 times the rated steady state current.
Using NTC/PTC thermistors in drone design generally is a bad idea. Also, I believe you want PTC, not NTC. But that’s tangential.
Cheers,
My preferred solution for dealing with inrush current is by using the XT90S connector. This type of connector has an integrated resistor which connects first when the connector is plugged in, slowly charging up the capacitors on the motor driver. When the connector is further plugged in, the resistor is then bypassed, and by this time the capacitors should be nearly fully charged up so there won’t be any large inrush current causing sparks.
If you mean the inrush current when starting the motor, then to reduce this you have to start the motor slower. Alternatively, you can use a controller capable of power limiting if you want a more accurate way of limiting the inrush current. However for a drone application, limiting the inrush current this way will really impact the performance of the drone during takeoff/acceleration, so my suggestion is to just buy batteries which can handle the higher peak currents.