VSI vs CSI VFD topology
VSI vs CSI VFD topology
(OP)
Hi,
Can someone explain when I should use a CSI (current source inverter) topology for the inverter of the VSD or when to use a VSI (Voltage Source inverter) kind?
Thanks.
Can someone explain when I should use a CSI (current source inverter) topology for the inverter of the VSD or when to use a VSI (Voltage Source inverter) kind?
Thanks.





RE: VSI vs CSI VFD topology
CSI is mostly used for large drives while VSI is used all over the power spectrum.
VSI (with PWM output) generates lots of EMI that cannot always be filtered away. But they are easy to control and are therefore used where tight speed or torque control is needed.
CSI is not suitable for drives where fast and precise control is needed because controlling them involves changing current in the huge DC link inductance. But, they do not generate as much EMI as VSI inverters do. And are sometimes more economical than large VSI inverters.
Mains Power Factor *can* be controlled in a VSI inverter but cannot be controlled in a CSI inverter. That alone may be a criterion to select a VSI.
All serious drive manufacturers can help you do the right selection.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: VSI vs CSI VFD topology
But a sometimes negative aspect to CSI technology was that the motors and drives had to be impedance matched. That meant replacing the motor with a spare meant a new commissioning procedure, usually performed by the CSI drive mfr. For some people, the time waiting for that to take place was undesirable.
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RE: VSI vs CSI VFD topology