What can be the explanation for flux optimization & flux braking feature and how can it be implemented for AC drives.
Kindly help to clarify the below mentioned two aspects for AC Drives(Induction Motor-in particular)

1)what is exactly FLUX OPTIMIZATION:- Is it something to do with adjusting the machine flux as per loading.In that case in V/F drives once we set the V/F ratio the flux gets adjusted as per input volts and frequency is it called flux optimization in V/F drives and how it can be implemented.

2)FLUX BRAKING:- Other aspect is flux braking that I understand is increasing motor flux so as to dissipate the extra energy in the motor as losses and hence the braking occurs.How can this be implemented in actual control.

Hi group,can we have discussion on flux optimization and flux braking for ac drives so as to make it very clear for me.

Regards,
Mukesh

Flux optimization, as it name itself suggest you have to operate your motor at optimized flux, i.e, the amount of flux by which total loss will be minimized. You need to built a loss model of induction motor by measuring the currents and other motor parameters and from there you can find get the optimized flux value by differentiating the total loss w.r.t to flux and equating to 0. In case of DTC & FOC it is quite easier as flux control is a part of it.

please note that when using v/hz controller, you don't actually use a linear curve. The best example is at 0 hz, if you were linear then you'd have no voltage and therefore no flux-so you adust the bend in the curve for motor mag. current. As you increase in both frequency and current, you have added resistive and inductive drops--therefore you must compensate by adusting the voltage which is another way of saying adjusting the air gap flux.

Thanks ken I understand working of V/F control technique.I was thinking how to implement flux optimization in FOC technique and how to decide how much flux optimization to give to a motor.Is it that it can be decided based on load current of the machine.
In case of FOC my d-axis current regulate the flux.So ultimately i will act on it for changing the flux but how much to regulate it based on load is the thing that troubles me.

best if the motor manufacturer gives you his single phase model, they will usually do this. Then it's not to hard to calculate your main drops. The hard one is the leakage inductance, but if you normalize your model, I'd start with about 18%.