Abstract
This paper investigates the use of the class-E inverter for power factor correction (PFC) applications. Analytical and state-space models are derived showing the class-E inverter's capability of achieving inherent PFC operation with a constant duty cycle. The inherent PFC operation limits the controller responsibility to the regulation of the output voltage, which is key for resonant converters with challenging control. A converter incorporating a diode bridge, a class-E inverter, and a class-D rectifier is presented for the PFC stage in single-phase offline converters. A prototype is designed to validate the analysis and presented design method. The prototype operates with zero-voltage switching (ZVS) across the load range and achieves up to 211 W of output power at an efficiency of 88%, with an inherent power factor of 0.99 and a total harmonic distortion (THD) of 8.8 %. Frequency modulation is used to achieve lower output power down to 25 W, with a power factor of 0.95, THD of 28 %, and an efficiency of 88 %.
Highlights
Large-scale deployment of switch-mode power supplies to the utility introduces line current harmonics
Several international standards expressly limit the magnitudes of input current harmonics and set a limit for the minimum power factor
A power factor correction (PFC) converter needs to be employed in offline converters for different applications to comply with these standards
Summary
Large-scale deployment of switch-mode power supplies to the utility introduces line current harmonics. Pulse width modulation (PWM) converters are employed for the PFC stage, including boost [3]–[6], buck [7]–[9], buck-boost [10]–[12], SEPIC [13], [14], Cuk [15], and flyback [16] topologies They offer high power quality and efficiency [17]. Their hard-switching nature results in high switching losses, which sets an upper limit for the switching frequency and, in turn, the power density. Their sharp switching current and voltage waveforms have high-frequency harmonic components, complicating electromagnetic interference (EMI) filters design.
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