Constitution and characteristics of neutral point clamped type inverter for driving LSM

In Japan, Maglev (magnetic levitation) system adopting a LSM (linear synchronous motor) with the primary side on the ground is under development as a new transportation system. This system needs a power converter with large capacity to drive the LSM which is able to generate variable voltage and variable frequency. For such a power converter, the authors produced a PWM (pulse width modulation) inverter which it is possible to operate as a neutral point clamped type (NPC type) at Miyazaki Maglev Test Track. The authors describe this inverter, laying emphasis on its characteristics and constitution.<>