Soft‐switching single‐stage three‐level power amplifier for high‐voltage audio distribution systems

Abstract

An isolated fully soft-switching single-stage three-level power amplifier (SS3L) based on dual auxiliary networks (DAN) is proposed in this Letter. Compared with the conventional class-D power amplifier, the proposed DAN-SS3L achieves high level of integration without bulky dc link capacitor, and high-efficiency by single-stage conversion and zero voltage switching for all the switches under different operating conditions from light load to full load, which is suitable for highvoltage audio distribution systems. By adopting active auxiliary network, the energy stored in the leakage inductor can be recycled, which eliminates the pulse width modulation voltage spikes. The passive auxiliary network provides enough reactive current for primary-side switches, extending soft-switching range. In addition, commutation overlap strategy is employed to enable natural commutation of bidirectional switches. Experimental results of a 200 W prototype are presented to verify the analysis results.

Soft switching modulation strategy based on bipolar (PSM) with improved efficiency in high-frequency link inverters

“…The three-level output generated by the Unipolar Pulse Width Modulation (UPWM) technique is a frequently applied modulation strategy for a Cascaded H-Bridge Full-bridge (CHFL) inverter. This approach enables bidirectional cyclo-converter switches to achieve natural commutation during the zero level of the modulation signal, thereby facilitating efficient Zero Voltage Switching (ZVS) (Guo et al, 2018;Guo et al, 2016). A Unipolar Pulse Width Modulation (UPWM)-based soft-switching push-pull high-frequency link inverter was proposed in (Chen et al, 2016a).…”

“…Owing to the rectification of the modulating signal, the output voltage quality was inappropriate (Chen et al, 2016a). A PSM-type UPWM-based inverter was proposed in (Guo et al, 2016), which does not require rectification of the modulating signals, but two auxiliary inductors were used to extend ZVS range at light load conditions. Addition of auxiliary inductor increases the component count for inverter.…”

“…Addition of auxiliary inductor increases the component count for inverter. The inverter proposed in (Guo et al, 2016) has low power level, and cannot be used in renewable energy applications. The commutation of the load current in the cycloconverter continues to yield voltage spikes on bidirectional switches (Guo et al, 2018;Wang et al, 2018).…”

“…The commutation of the load current in the cycloconverter continues to yield voltage spikes on bidirectional switches (Guo et al, 2018;Wang et al, 2018). Overlap commutation switching techniques have been implemented in previous studies (Mazumder and Rathore, 2011;Zhu et al, 2014;Guo et al, 2016) to achieve zero voltage switching (ZVS) of bidirectional switches in cycloconverters. However, a resonance issue arises between the leakage inductance of the transformer and the output capacitance of the bidirectional switches, leading to electromagnetic interference (EMI) (Gandikota and Mohan, 2014;Korkh et al, 2019;Wang et al, 2022).…”

“…The auxiliary circuit amplifies the complexity and expense of the system (Zhong et al, 2018). Unipolar Pulse Width Modulation (UPWM) creates the problem of zerocrossing distortion and a narrow pulse on the transformer's primary side (Guo et al, 2018;Zhu et al, 2014;Guo et al, 2016). Leakage inductance is another factor contributing to duty cycle loss, resulting in a decreased effective duty cycle on the secondary side.…”