A new approach to hysteresis modulation techniques for NPC inverters

High power IGBT devices have improved their performances more and more over the last decade. However, the maximum supported voltage by available high-voltage IGBTs does not allow the employment of standard voltage source inverters in some high power applications, such as high-speed traction drives. A reduction of the maximum drop voltage on the switches devices can be achieved by a neutral point clamped (NPC) inverter. The paper proposes two different solutions to obtain a current control of NPC inverter drives. Both the solutions are based on a new hysteresis modulation technique, easily implementable on a programmable logic device. Moreover, a performances comparison is presented.