Design and Implementation of Five level back to back Diode Clamped PWM Converter for AC Drives

The work describes a transformer less medium voltage adjustable-speed induction motor drive consisting of two back-to-back connected five-level diode-clamped converters. Due to the feedback from the load to the dc link nodes, there is a chance of voltage imbalance. In this paper the methods for voltage balancing are discussed and simulated. The usage of switching techniques to employ voltage balancing rather than the external circuitry is being discussed. Proper switching results in the control of average current through the nodes and hence the non symmetrical charging and discharging of the dc split capacitors can be avoided. The first phase of work explains the output using the multicarrier pulse width modulation technique and the second phase deals with the modification done using the Space vector Pulse Width Modulation (SVPWM) technique. Voltage balancing is achieved with lesser harmonic content while using the SVPWM technique.