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The single-phase boost power factor correction (PFC) converter serves as the fundamental energy conversion unit to convert the electrical energy from the ac form, which is delivered by the utility grid, to the electrical energy in dc form, which is accepted by a variety of consumer electronics circuits. In this paper, a resonant controller based compensation method is proposed and verified. The method enables boost PFC converter to reduce the amount of harmonic current it draws from the input ac side when there exist harmonic distortions in the ac side input voltage. The proposed method could reduce the need for the centralized active harmonic filters, especially for small scale power grid that has tight harmonic requirements. Experimental result is documented, and it shows the effectiveness by using the proposed control method.

This paper investigates the use of active damping for suppressing transient oscillations in the trans-rotary magnetic gear (TROMAG). As a type of magnetic gear, TROMAG suffers from a low stiffness. When used in applications such as backpack energy harvesting or wave energy conversion, low stiffness of TROMAG could result in long-lasting oscillations in the system response to sinusoidal excitations. It is shown here that active damping, realized through feedback from the rotor speed, can effectively suppress such oscillations.

This paper presents a method for estimating the positive and negative sequence grid voltage under unbalanced grid conditions using simple algebraic and trigonometric identities without dedicated grid voltage sensors in three phase grid connected boost rectifier converter system. The estimated voltages are then used to control the positive and negative sequence currents of the boost rectifier. The estimation method is based on the positive and negative sequence active and reactive power delivered by the converter to the grid. In addition to the estimation of the positive and negative sequence grid voltage, the proposed method also generates an estimate of the frequency information of the grid similar to a conventional PLL structure. Detailed theory and results confirm the feasibility of the proposed scheme.

The Class E dc-dc converter, featured with simple topology and easy realization of zero-voltage-switching (ZVS) for the power switch, could operate with the switching frequency up to multi-megahertz. In such a high switching frequency, the ON-OFF control, characterized with fixed switching frequency and fixed duty cycle, is usually adopted. With this control scheme, traditional design approaches are no more applicable because the output voltage is independent of the energy conversion function. In this paper, an optimized parameters design is proposed for the Class E dc-dc converter with ON-OFF control. With this design approach, the converter's duty cycle is optimized accounting for the minimum switch voltage stress and minimum switch root-mean-square (RMS) current; the power stage parameters are step-by-step designed according to the four basic requirements of the Class E dc-dc converter, namely, the allowable input current ripple, the realization of zero voltage switching for the power switch, the demand of rated output power, and the sinusoidal assumption of the resonant current. Finally, a 20MHz, 10W laboratory prototype is built and tested in the lab, and the experimental results are presented and compared to verify the effectiveness of the optimized design.

High efficiency and high power density are critical in megawatt-class mechanical-to-electrical energy conversion systems that operate within a limited speed range, as in wind- and gas-turbine-driven generators. Generator output is connected to an ac-to-dc conversion system for processing and controlling power flow to an electric grid. Conventional high-power ac-to-dc conversion architectures rely heavily on active rectifiers, which consist of fully-controlled power-electronic switches. These make the system bulky, lossy, and less reliable. This paper presents an alternative approach: integrating a multi-port permanent-magnet synchronous generator (PMSG) with series-stacked power converters. An active rectifier processes only a fraction of the total converted power while regulating the dc bus. The remaining power is processed by diode bridges, which allows a substantial increase in overall efficiency, power density, and reliability. Theoretical analysis shows that for wind-power generation applications, the active rectifier processes a maximum of 25% of the rated power while the PMSG operates in a speed range similar to the conventional doubly-fed induction machine. The conversion loss is reduced by 66%. Results from a laboratory-scale experimental setup corroborate the proposed architecture. This approach potentially increases integration of medium-voltage dc distribution to the megawatt-class mechanical-to-electrical energy conversion systems to achieve higher efficiency, power density and lower cost.