I have read papers on multilevel inverter feeding BLDC motor drives. My question is BLDC motor having trapezoidal back-emf, is it possible to drive the BLDC motor using an l inverter that gives a perfectly sinusoidal voltage output? Also, I would like to get clarified about the stability of such a drive and torque ripple. I will be grateful to you if you could kindly let me know the significance of such an inverter application to BLDC motor drives.
Sinusoidal wavform consists negativa and positive halfcycles. if you rectifies the waveform, then you can use the inverter for controlling the BLDC. Of course you should chane the pulse control of the switches for better working.
A MLI generates a square or stepped waveform ( non sinusoidal). Use a Rectifier , to control a BLDC motor. The inverter output voltage or gain or switches can be controlled using pulse width modulation technique.
The stability in general depends not only on the inverter but also on the control software (i.e., controller designs). If the latter is designed in a proper way, controlling a BLDC with a multilevel inverter should be unproblematic.
However, BLDCs are generally considered low-cost motors while multi-level inverters cause increased costs due to an increased number of power electronic components compared to standard two-level inverters. Hence, that is an unusual match. Moreover, if you want to supply nearly ideal sinusoidal voltages / currents to the BLDC you will receive relatively large torque harmonics since the electromagnetic design of the BLDC is not optimized for this operation.
Dear Madam
Yes, it is possible, but in that case You have to change control of Your motor.
You have to treat the BLDC as an synchronuous motor and apply frequency control, remebrering of U/f fomula on the output of Your MLI.
You start Your drive with a low frequency and voltage and then You control the speed by changing frequency of supply, adjusting the voltage accordingly.
With such drive You forget the electronic commutator and control the drive directly by the output ferquency of Your MLI.
Best wishes - Piotr Wach, Opole, Poland
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