Systematization of a Multilevel-Topology-Based Linear Amplifier Family for Noiseless DC–AC Power Conversion

Electrical power converters use semiconductor switching devices for larger loss reduction compared with non-switching power linear amplifier such as a class-B amplifier. However, it is well known that the switching operation produces harmonics and EMI noise, thus passive components are usually required for the suppression of these harmful sub-products. Use of recent fast power devices such as silicon carbide (SiC) and gallium nitride (GaN) devices produce larger dv/dt and di/dt than that of Si power devices and as a result above mentioned problem becomes more tangible. In this paper, the authors propose a concept of a family of multi-level linear amplifier (MLLA), which makes no switching power conversion possible. MLLA consist of series-connected switching devices and only one of them operates as a linear amplifier and the loss is much less than that of the class-B amplifier. The concept of the family is very useful when a proper MLLA topology might be selected for applications. In this paper, three kinds of MLLA—diode-clamped linear amplifier (DCLA), flying-capacitor linear amplifier (FCLA), and novel modular-cascaded linear amplifier (MCLA)—with four series connection of devices are investigated for the viewpoint of merits and demerits clarification and the efficiency over 82 % is demonstrated in the experiments.