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Topic: BLDC Motor Controller Using Arduino (Read 81011 times) previous topic - next topic

arnolde

So you need 3-phase bridge, current sensors on two of the phases
Sorry for responding so late to an old post, but I just gotta know ;-)

Why does he need current sensors if he has hall sensors?
I thought you only need current sensors to "guess" the rotor position if you don't have any other feedback?
Or is that for safety (blocked/overloaded motor) conditions and not technically necessary to run the motor?

MarkT

#31
Sep 26, 2020, 11:18 am Last Edit: Sep 26, 2020, 11:22 am by MarkT
Sorry for responding so late to an old post, but I just gotta know ;-)

Why does he need current sensors if he has hall sensors?
I thought you only need current sensors to "guess" the rotor position if you don't have any other feedback?
Or is that for safety (blocked/overloaded motor) conditions and not technically necessary to run the motor?
The question was about a 10hp AC (ie sinusoidal) drive of a 3-phase motor.  This is done using
an inner current loop to set the torque, and outer speed or position control loops that control the current
loop to achieve their set-points.

Without current sensors you cannot do a current control loop, basically - precluding accurate closed loop
control.

Hall sensors are only used with trapezoidal drive.  A 10hp motor would typically be sinusoidally
driven for better efficiency and to reduce cogging/vibration which at those power levels can be a
big problem mechanically, leading to fatigue and other issues.

Furthermore current sensors for that size of motor allow the winding temperature to be
estimated and the thing protected from over-heating.

If the motor is an induction motor field-oriented control is usually employed and current
sensing is very useful for this too.

Some reading/viewing:
https://www.amazon.co.uk/Electric-Motors-Drives-Fundamentals-Applications/dp/0080983324
https://www.youtube.com/watch?v=fpTvZlnrsP0&t=1874s
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]

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