Non‐ideal behavior of ZVS inverter comprising variable and fixed frequency operation: Analysis, compensation, and verification

Abstract

• ZVS inverters based on TCM with frequency limit allow for high efficiency. • Nonidealities can impact output waveforms of ZVS inverters. • Propagation delay, filter capacitor, and DC-link capacitor worsen output waveforms. • Detailed analysis leads to suitable compensation methods. • Implementing these in the modulation scheme delivers smooth waveforms with low THD. This paper presents a study of a two-level inverter. It proposes a modulation scheme for inverters featuring zero-voltage switching (ZVS) with both fixed and variable switching frequency operation. The control scheme uses a hybrid method to determine the switching actions of the half-bridge consisting of a current threshold detection circuit and predictions from numerical evaluations of fundamental waveforms of an ideal half-bridge circuit. Compared with conventional fixed frequency PWM inverters, the inverter in this study exhibits higher rms currents but eliminates switching losses. As several components in practical setups of the inverter inevitably introduce non-idealities, a study of these and their impact on the output waveforms follows. The study comprises the propagation delay of the current threshold detection circuit, the filter capacitance, and the DC-link capacitance. Our study demonstrates the need to consider these effects. We show that smooth output waveforms can be achieved for low and high voltage applications if these effects are properly taken into account in an experimental setup. The total harmonic distortion (THD) is used to evaluate the output waveform quality, which is 0.81% when all effects are properly considered, © 2017 Elsevier Inc. All rights reserved.