Multilevel Fixed Pulse Pattern Control for Medium Medium-Voltage High High-Frequency Inverter

Abstract

To satisfy the demand for more compact medium medium-voltage motor drive systems, it is desirable to increase the frequencies of cascaded H H-bridge inverters used in high high-speed motor systems. However, in asynchronous pulse pulse-width modulation (PWM) systems, as the output frequency increases, the command voltage and triangular wave carrier frequencies become closer, making it impossible to output the command voltage accurately. This manifest manifests in the form of increased current harmonics, increased surge voltage at the motor terminals, and in creased low low-frequency ripple current owing to the asynchronous nature of the system. In this study, we adopt a fixed pulse pattern modulation method to address these problems. In our method, a low low-distortion output voltage without multiple simultaneous changes is compiled into a table in advance, and subsequently output in synchronization with the fundamental voltage phase. We were able to confirm the effectiveness of the proposed method via simulations and mini mini-model experiments at fundamental wave frequencies of 700 Hz and 1000 Hz.