High frequency quasi-square AC distributed power systems simplify the complexity of DC distributed power systems at the expense of greater generated EMI due to high values of dV/dt and dI/dt displayed in the bus waveform characteristics. To quantify EMI effects, the bus structure of a 300 kHz quasi-square waveform AC distributed power system is analyzed using the partial element equivalent circuits (PEEC) method incorporated in the software package InCa. Simulation and experimental results are compared and design guidelines to minimize EMI effects in AC distributed power systems are given

The design and implementation of a high-frequency AC distributed power system is presented. The system utilizes a 300 kHz, 50 V peak soft-transition square wave for AC voltage distribution. Load converter designs consisting of 50 W regulated resonant rectifiers yield sinusoidal bus currents. This, coupled with the soft-transition bus voltage wave shape, reduces the potential for noise interaction with the host system. Bus regulation is accomplished through a simplified front-end design consisting of a boost PFC converter cascaded with a soft-switched half-bridge inverter. Experimental results are presented for operation at 5 Vdc and 100 W output.

Flyback derived topologies are attractive because of their relative simplicity when compared with other topologies used in low power applications. Incorporation of active-clamp circuitry into the flyback topology serves to recycle transformer leakage energy while minimizing switch voltage stress. The addition of the active-clamp circuit also provides a mechanism for achieving zero-voltage-switching (ZVS) of both the main and auxiliary-switches. ZVS also limits the turn-off di/dt of the output rectifier, reducing rectifier switching losses and switching noise due to diode reverse recovery

Flyback derived power convertor topologies have long been attractive because of their relative simplicity when compared with other topologies used in low power applications. Incorporation of active clamp circuitry provides the additional benefit of recycling transformer leakage energy while minimizing switch voltage stress. This paper presents the analysis, design, and experimental results of 500 W single stage and 600 W interleaved active clamp flybacks used for power factor correction. Several practical issues, including the application of charge control, the use of mixed power devices, and a solution to the hold-up time problem are discussed and experimentally verified

A new full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation. The active-clamp network serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching. PWM phase-shift control of the bridge switches is utilized to obtain zero-current switching for two of the four bridge switches. Simulation results are presented which verify the principle of operation.

This paper presents design considerations for power converter modules used in a distributed power system, including front-end power converter modules and load power converter modules. The system is designed for a universal input voltage of 90-260 V AC, with a bus voltage of 48 V DC. Several versions of the 600 W power factor corrected front-end power converter modules have been evaluated. One configuration includes a zero-voltage-transition PWM boost PFC circuit followed by a zero-voltage-switched active-clamp forward power converter. The second configuration uses an interleaved active-clamp flyback power converter for both the power factor correction and bus voltage regulation. 150 W and 300 W load power converter modules with 5 V output have been developed using the active clamp forward power converter topology and low-profile magnetics

The design and breadboard implementation of a constant-frequency, zero-voltage-switched, full-bridge pulsewidth modulation converter delivering a 12-V-at-1-kW output from a 350-450-Vdc input bus is described. The zero-voltage switching characteristic is maintained over a wide operating range by utilizing the transformer magnetizing inductance as an energy storage element. Output voltage regulation is accomplished entirely on the secondary side through magamp control, thus simplifying the methods used for maintaining control and isolation.