Totem-Pole Power-Factor-Correction Converter under Critical-Conduction-Mode Interleaved Operation

Abstract

SUMMARYThis paper proposes a new power-factor-correction (PFC) topology, and explains its operation principle, its control mechanism, related application problems followed by experimental results. In this proposed topology, critical-conduction-mode (CRM) interleaved technique is applied to a bridgeless PFC in order to achieve high efficiency by combining benefits of each topology. This application is targeted toward low to middle power applications that normally employs continuous-conductionmode boost converter.

GaN-based high frequency totem-pole bridgeless PFC design with digital implementation

“…and then (4), (5) and (6) can be simplified accordingly. Naturally it is also valid that in the condition statement of (5), the duty cycle command can also be replaced by the AC voltage.…”

“…2(a) as an example, the top switch S lf(T) should be on, according to (5) while the AC current is positive which means the current need to flow through the channel of this current-bidirectional switch. In contrast, a current-unidirectional switch, say a diode, disallows for the conduction in this case and current distortion, although maybe tiny, will occur.…”

“…The four gate drivers will then translate the gate PWMs into the phase leg output voltage. The implementation of those blocks have certain physical limitations which will violate the rules in (5). Here we will examine two most critical scenarios that can make the v hl waveform incorrect, namely, the long transition time of the low frequency leg, and the minimum pulse width limit of the high frequency leg.…”

“…This characteristic, as will be detailed later, actually makes the controller, modulator and gate driver design tricky. One widely reported issue is the current spike at the zerocrossing of AC voltage [4,7,10]. Contrary to the well reported zero-crossing current distortion phenomena in [11][12][13][14], which mainly associated with current controller design and discontinuous conduction mode operation, this zero-crossing current spike relies more on the modulator, as will be detailed in this paper.…”

“…However, traditional totem-pole PFC converter uses silicon super junction MOSFET, thus suffers from severe reverse recovery of the MOSFET body diode when operating in continuous conduction mode (CCM). Therefore, usually critical-conduction mode (CRM) is used to achieve zerovoltage-switching or valley switching to overcome the impact of the diode reverse-recovery and high switching loss at turnon [4,5]. In addition, by replacing the two rectifier diodes with two big MOSFETs, the resultant active H-bridge enables the converter to achieve more flexible controllability therefore more advantages, such as: extended ZVS range for the fast switches, bi-directional capability and low condition loss compared to the pure diode solution [6].…”