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This article proposes a voltage-fed zero-voltage-switched topology based on the push–pull converter. The proposed converter uses the leakage inductance of the transformer to transfer power from input to output. Phase-shift modulation strategy is used to control the flow of this power. A coupled LC regenerative snubber-based energy recovery circuit reclaims the trapped energy in the leakage inductance. The snubber circuit also ensures soft-switched operation and reduces the voltage stress across the semiconductor switches. The power-flow equation is characterized and experimentally verified for the proposed converter. The gate control signals are implemented using an field-programmable gate array (FPGA). A 240-W prototype validates the steady-state behavior and snubber design equations. [ABSTRACT FROM AUTHOR]

Nonisolated dc–dc converters are fundamental building blocks in the power supply for a wide range of applications. To cater to this heterogeneity in applications, development of dc–dc converters with suitable voltage conversion ratio (G) is imperative. Given a converter topology, G can be found out uniquely by using the principle of inductor volt-second balance, and the process of obtaining the voltage conversion ratio from the topology is simple. In contrast, the inverse problem, i.e., the process of obtaining the converter topology for a given voltage conversion ratio (G) is a challenging task, and the obtained topology is also not unique. This article presents a simple method to obtain a family of converter topologies from a required voltage conversion ratio. This method utilizes the principle of inductor flux balance as a synthesis tool. The step-by-step procedure to synthesize the converter topologies is outlined. To illustrate the efficacy of the proposed method, it is applied to synthesize various quadratic buck–boost topologies, and a family of converters is identified. Operation and feasibility of two novel topologies, identified by the proposed theory, are verified experimentally. [ABSTRACT FROM AUTHOR]

This paper describes a theory to synthesize nonisolated dc–dc converters. It uses the fundamental flux balance equation across the inductors of a converter as a starting point in this synthesis process. The flux balance equations are the linear equations of the input voltage, capacitor voltages, and duty cycle (D). The coefficients of these linear equations can be selected from a finite set of choices. These choices define the converter topologies that are subsequently used to synthesize a converter. The synthesis procedure applies to a converter of multiple order. All the possible converters are identified for a first-order topology. In the case of second-order converters, all the choices of the flux balance equation are defined. Based on these choices, three new quadratic topologies are derived and verified to demonstrate the effectiveness of the theory. The procedure to synthesize a converter from a given voltage conversion ratio is also outlined. [ABSTRACT FROM AUTHOR]

Due to the pulsating power at the inverter output terminals, the passive storage elements of the boost stage of the current-fed switched inverter (CFSI) contain a power frequency harmonic component (100 Hz), apart from dc and switching frequency components. In prior designs, the second harmonic component is suppressed by increasing the size of the input filter inductor and capacitor or by using additional circuits. This paper presents a complete characterization of a control-based approach to suppress the power frequency harmonic component in the input inductor current of a CFSI. It also presents a comprehensive characterization of the harmonic power redistribution. Using the proposed approach, it is demonstrated that the inductor value of a CFSI is reduced by 61% for the same peak-to-peak ripple. This leads to an improvement in the conversion ratio, efficiency, and power density of the overall converter. A SiC MOSFET-based CFSI with 75-kHz switching frequency is used to verify the proposed design philosophy. [ABSTRACT FROM AUTHOR]

Dielectric elastomer generator (DEG) is a special variable capacitor generator used to harvest electrical energy from ambient mechanical vibrations, such as waves, building vibrations, wind, and human movement. The DEG, by virtue of its variable capacitance, converts the applied mechanical energy into electrical form. For successful energy harvesting, the DEG requires controlled charging and discharging operations. Thus, the energy harvesting circuits, used to charge and discharge the DEG, must work in tandem with the mechanical vibrations. The energy harvested during a single cycle of DEG operation increases with an increase in the DEG operating voltage. Hence, energy harvesting circuits must drive the DEG at high voltage levels. These two requirements make the energy harvesting circuit design a challenging job. In this paper, a novel energy harvesting system is proposed to drive the DEG without needing a position sensor, a high-voltage source, or a high turns ratio transformer. The theory of the proposed scheme is explained and validated with experiments performed on a prototype DEG. The control implemented leads to a special intermittent operation of the energy recovery circuit, which is also introduced. 2.597 mJ energy was harvested from a single elastomer film of 10 cm diameter with 2.3 nF capacitance in relaxed condition. [ABSTRACT FROM AUTHOR]

Impedance source inverters (ISIs) are gaining attention due to features such as single-stage conversion, buck-boost capability, and inherent shoot-through protection. To maintain the required ac output voltage, typically ISIs are operated at a higher dc-link voltage due to constrained modulation index. This also increases voltage stress across capacitors and switches of the converter. This voltage stress is approximately double compared to that of voltage source inverter with preboost stage (Boost-VSI). To mitigate this problem, a new pulsewidth modulation (PWM) scheme for the active-front-end based ISIs (AFE-ISIs) is proposed. The proposed scheme enables the ISIs to produce high ac gain with lower voltage stress across the capacitor and switches. In other words, the proposed scheme blends the advantages of Boost-VSI into ISIs. With the new PWM scheme, there are also reductions in output voltage total harmonic distortion, switching frequency ripple in the inductor current, and power loss in the converter. A prototype of the current-fed switched inverter, an AFE-ISI, is designed, and the proposed PWM scheme is implemented. Experimental results obtained are in accordance with the proposed theory and show that the voltage stress has reduced from 325 V to 203 V for an ac output of 110 V. [ABSTRACT FROM AUTHOR]

Elastomer is an electroactive polymer, which finds popular application in the field of actuators and artificial muscles. Though elastomers are popularly used as actuators, with proper modification to their operating cycle, they can also be used as generators. These dielectric elastomer generators (DEGs), due to properties such as high energy density and frequency independent operation are suitable for different energy harvesting applications. In this letter, a simplified electrical model of the DEG is proposed, which can be used in various simulation platforms to verify compatibility of DEG with electrical circuits and predict its behavior. Detailed process of deriving the model parameters from a physical DEG is discussed at length. Performance of the proposed model is verified by comparing its behavior with a prototype DEG-based energy harvesting system having a DEG of 1.3 nF capacitance. The proposed DEG model was simulated with similar conditions and the simulation results have shown good accuracy with the experimental results. [ABSTRACT FROM PUBLISHER]

The Z-source inverter (ZSI) employs an LC impedance network between the main inverter bridge and the power source. The unique feature of the ZSI is that it can operate either in buck or boost mode with a wide range of obtainable output voltages from a given input voltage. This topology also exhibits better electromagnetic-interference noise immunity when compared to a traditional voltage-source inverter (VSI). However, the LC impedance network of ZSI significantly increases the size and cost of the power converter and can make it unsuitable for low-power applications. This paper proposes a novel topology called switched boost inverter (SBI) which exhibits similar advantages of ZSI with lower number of passive components and more active components compared to ZSI. The steady-state and small-signal analyses of SBI, along with its pulsewidth modulation (PWM) control strategies, have been discussed in this paper. This paper also presents a comparison of SBI and ZSI with the same input and output parameters. The theoretical analysis given in this paper has been validated using a laboratory prototype of SBI, and the experimental results are presented for verification. The experimental harmonic spectrum of the inverter's output voltage with the proposed PWM technique is also plotted and compared with that of a traditional VSI. All the experimental results show good correlation between theory and experiments. [ABSTRACT FROM PUBLISHER]

Switched boost inverter (SBI) is a single-stage power converter derived from Inverse Watkins Johnson topology. Unlike the traditional buck-type voltage source inverter (VSI), the SBI can produce an ac output voltage that is either greater or less than the available dc input voltage. Also, the SBI exhibits better electromagnetic interference noise immunity when compared to the VSI, which enables compact design of the power converter. Another advantage of SBI is that it can supply both dc and ac loads simultaneously from a single dc input. These features make the SBI suitable for dc nanogrid applications. In this paper, the SBI is proposed as a power electronic interface in dc nanogrid. The structure and advantages of the proposed SBI-based nanogrid are discussed in detail. This paper also presents a dq synchronous-reference-frame-based controller for SBI, which regulates both dc and ac bus voltages of the nanogrid to their respective reference values under steady state as well as under dynamic load variation in the nanogrid. The control system of SBI has been experimentally validated using a 0.5-kW laboratory prototype of the SBI supplying both dc and ac loads simultaneously, and the relevant experimental results are given in this paper. The low cross regulation and the dynamic performance of the control system have also been verified experimentally for a 20% step change in either dc or ac load of SBI. These experimental results confirm the suitability of the SBI and its closed-loop control strategy for dc nanogrid applications. [ABSTRACT FROM AUTHOR]