High performance, high reliability medium voltage drives

During the past decade medium voltage drives have undergone considerable advancement as a result of innovations in circuit topologies, switching devices, control techniques and microprocessors. This paper shows that a combination of the series-cell, multi-level topology and the latest control technology can provide scaleable architecture, good input and output power quality, high performance and reliability in medium voltage drives. A new feature that vastly improves the reliability of the system, called transparent cell bypass, is presented. Another novel feature that allows braking torque to be produced in nonregenerative drives is also described.