New medium voltage PWM inverter topologies for adjustable speed AC motor drive systems

In this paper new PWM voltage source inverter topologies suitable for adjustable speed operation of medium voltage (690 V, 2300 V, 3300 V, 4160 V) induction motor drives are introduced. The new inverter topologies are derived from an optimum combination of several three phase and single phase PWM inverter modules. These modules employ low voltage high current IGBT devices and can be viewed as power electronic building blocks (PEBBs). The proposed medium voltage inverters exhibit high quality PWM output with low dv/dt, modular construction with built-in redundancy, lower DC-link capacitive energy storage compared to other structures and are flexible for different medium voltage ASD applications. A method to eliminate bulky input transformers is shown. Issues of input current quality are also addressed. Simulation results are presented to validate the concepts