Şöyle bir makale buldum:
Robert Glickman & Thomas Bernhardt, ABB Inc
......
Alternatively, the drive could allow the motor speed to decrease and use the energy stored in the inertia of the load to maintain bus voltage. Typically, more energy is stored in the load's inertia than the DC bus, making it possible to hold bus voltage for as long as 0.5 second to 5 seconds.
.....
During normal operation, the input voltage to a drive is balanced and the diodes in the bridge rectifier are symmetrically forward-biased. A phase imbalance acts to lower the magnitude of one or more line-to-line voltages, reducing the peak voltage for one or more phases below the nominal capacitor voltage. This causes the rectifier diodes to not forward-bias. In this state, no energy flows from the AC mains to the capacitor. The capacitor will continue to discharge until it's hit by an input voltage peak that's high enough to forward-bias the diodes.
Since the capacitor has discharged more than its normal amount, the current drawn from the AC mains to recharge it to peak voltage will be quite high. In fact, the rms input current on some phases might exceed 200% of normal rating, and the associated peak current drawn in the high-current phase may be as much as four times the normal current (
Fig. 1 on page 26). Under these conditions, an AC drive will often trip on overcurrent because the line current was too high or on undervoltage because the DC bus dropped below some threshold.
You'll see similar effects when single-phase loads are unevenly distributed on a 3-phase power system. The solution is to balance these loads more evenly across all three phases or install an AC line reactor at the AC drive that's experiencing problems. You should size the reactor to carry the drive's full load current, and it should have an impedance rating from 2% to 6%.
.....
Yani diyorki fazlarda dengesiz voltaj varsa diyotlar doğru şekilde ileri kutuplanmayacağı için AC gerilim DC'ye çevrilemeyecek, düşük gerilim ile dahi DC baradaki kondansatörler de şarj edilemeyecek. Yani iyice şapa oturcaz diyor. Elimizde sadece yavaşlayan motorun ürettiği rejeneretif enerji var, onula DC barayı şaj edecez diyor.
Sürücünün nominal akım değerinde ve empedans değeride % 2-%6 arası giriş AC hat reaktörü takarsanız iyi edersiniz diyor. Ben böyle anladım.