SINADR

Abstract: This paper presents a comprehensive model for miniature vibration-powered piezoelectric generators and analyses modes of operation and control of a buck-boost converter for the purpose of tracking the generators optimal working points. The model describes the generator's power dependence with the mechanical acceleration and frequency, and helps in the definition of the load behaviour for power optimization. Electrical behaviour of the input of buck-boost converter in discontinuous current mode turns out to be in perfect agreement with the considered optimization criteria with a very simple, sensorless control. Experimental results show that the converter controlled by a very low consumption circuit effectively maximizes the power flow into a 4.8 V rechargeable battery connected to the converter output. The converter's efficiency is above 84% for input voltages between 1.6 and 5.5 V, and for output powers between 200 muW and 1.5 mW. The presented circuit and control can be used as well for power optimization of electromagnetic energy harvesting devices.

Abstract: The authors present an improved soft-switching full-bridge converter which is especially suitable for high-power application (e.g. more than 1 kW output) because of its inherently high efficiency. The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulse width modulation) full-bridge DC-DC converter substantially reduced the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors analyze the conditions for lossless transitions, discuss the effect of the added components on the operation of the converter, and present practical considerations and test results for a 1.5 kW converter with 100 kHz clock frequency. The converter has an efficiency above 95% at 60 V output, is free from voltage overshoots, and exhibits well-controlled transitions for all switch and rectifier voltages and currents. >

Abstract: This paper proposes a new high step-up dc-dc converter designed especially for regulating the dc interface between various microsources and a dc-ac inverter to electricity grid. The figuration of the proposed converter is a quadratic boost converter with the coupled inductor in the second boost converter. The converter achieves high step-up voltage gain with appropriate duty ratio and low voltage stress on the power switch. Additionally, the energy stored in the leakage inductor of the coupled inductor can be recycled to the output capacitor. The operating principles and steady-state analyses of continuous-conduction mode and boundary-conduction mode are discussed in detail. To verify the performance of the proposed converter, a 280-W prototype sample is implemented with an input voltage range of 20-40 V and an output voltage of up to 400 V. The upmost efficiency of 93.3% is reached with high-line input; on the other hand, the full-load efficiency remains at 89.3% during low-line input.

Abstract: This paper contributes to the steady-state analysis of the bidirectional dual active bridge (DAB) dc-dc converter by proposing a new model that produces equations for rms and average device currents, and rms and peak inductor/transformer currents. These equations are useful in predicting losses that occur in the devices and passive components and aid in the converter design. An analysis of zero-voltage switching (ZVS) boundaries for buck and boost modes while considering the effect of snubber capacitors on the DAB converter is also presented. The proposed model can be used to predict the converter efficiency at any desired operating point. The new model can serve as an important teaching-cum-research tool for DAB hardware design (devices and passive components selection), soft-switching-operating range estimation, and performance prediction at the design stage. The operation of the DAB dc-dc converter has been verified through extensive simulations. A DAB converter prototype was designed on the basis of the proposed model and was built for an aerospace energy storage application. Experimental results are presented to validate the new model for a 7 kW, 390/180 V, 20 kHz converter operation and the ZVS boundary operation.