Multi-Level Topology Based Linear Amplifier Family for Realization of Noise-Less Inverters

Nowadays, all of power converters utilize switching operation to reduce losses of semiconductor power devices. However, the switching operation causes high harmonics, high electromagnetic interference (EMI), and enlarging passive components in a circuit. These are the typical issues in the power electronics, because dv/dt and di/dt in a power converter tend to high due to practical use of SiC and GaN devices with high-speed switching capability. In this paper, multi-level topology based linear amplifiers (MLLA) without the switching operation are proposed for realization of noise-less inverters. Although the conventional linear amplifier such as the class-B amplifier generate large loss due to a linear operation, MLLA can reduce the loss by multiple series connection of MOSFETs. Three basic topologies, diode-clamped linear amplifier (DCLA), flying-capacitor linear amplifier (FCLA), and modular-cascaded linear amplifier (MCLA) are introduced and summarized as the MLLA family. The operation principles of the three basic topologies are quite similar, and loss generated during a linear operation in the MOSFETs become smaller, as the number of series connected MOSFET increases. These features enable to realize a noise-less inverter with high efficiency even compared with the PWM inverters. Finally, it is verified that 4-series circuits of the DCLA, FCLA, and MCLA achieve higher efficiency of 82% despite of the linear amplifier without the harmonics and EMI.