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per-phase current control

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pf26
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Joined: 2018-12-04 08:44
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per-phase current control

Hello, I'd like to make a 3 phase balancer using VESC, in other word, I want it to connect to a 3 phase grid, and be able to inject/take power from one or another phase so as to reduce voltage imbalance. This is quite similar to a 3 phase grid connected inverter, but requires per-phase current control, and no-shift svm so I can connect neutral line to Vdc/2 . So I digged (again) into the mcpwm_foc function, and and was scared how it got more complicated than it used to be (with addition of HFI, double motors..) So I am near to give up this route, unless maybe someone already tried working on this ? 

Also I think per-phase current control may be of interest for motor control, as motor with very low turn count windings may have bemf imbalance, leading to (stronger) current imbalance, loss of efficiency and possibly control issues. I am not able to evaluate to what extend it may come true, but certainly a few percent difference in bemf leads to high current differences when winding resistances are low..

Thks for help, Pierre

vadicus
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Joined: 2018-08-17 07:26
Posts: 431

What is the voltage of the grid are we talking about?

Vesc6 designs already has current sensors on each of the three phases and currents are already balanced out. Low turn (low resistance and low inductance) motors are harder to control but vesc design does it better than most other designs out there already.  

 

 

NextGen FOC High voltage 144v/34s, 30kw (https://vesc-project.com/node/1477)