A novel PWM scheme for a three-level voltage source inverter with GTO thyristors

This paper presents a new PWM method for the three-level GTO inverters based on the space voltage vectors. With the proposed PWM method, we can minimize the harmonic components of the output voltage by avoiding the minimum pulse width limitation problem of the GTO thyristors and keeping the voltage balancing of the DC-link capacitors. The principle of the proposed PWM method and the voltage vector output sequences are described in detail. Computer simulation and experimental results verify that the proposed PWM method is suitable for high voltage and large capacity three-level GTO inverters applied to induction motor drives.