The contribution of switch resistances to the losses in switched-capacitor converters (SCC) is reevaluated. The results reaffirm the crucial role that the switch resistances play in the design of ...open-loop and regulated SCC.
This paper presents the development, analysis, and performance evaluation of a new topology for an isolated dc power electronic converter (PEC). The proposed topology (called the reverse flyback dc ...PEC ) is developed to process a discontinuous input voltage and produce a continuous output voltage. The reverse flyback dc PEC is operated based on charging the inductive element in the high-frequency transformer, while discharging the energy to the output side through on - off actions of the switching element, which is located on the secondary side of the high-frequency transformer. A prototype for the proposed reverse flyback dc PEC is constructed to evaluate its performance under different operating conditions. Performance results show that the reverse flyback dc PEC is capable of processing discontinuous input voltages with different duty ratios and maintaining continuous output voltages with a minor sensitivity to the load type of ratings.
In this paper, a family of switched-resonant converters with high efficiency over a wide conversion ratio range is introduced. Inspired by the gyrator resonant switched-capacitor concept, the new ...topology provides high efficiency over wide and continuous range of conversion ratios using a single resonator. This is enabled by new modes of operation (switching sequences) developed and analyzed in this paper that modify the charge balance of the flying capacitor. By that, the sourcing as well as the efficiency characteristics of the converter can be shaped to peak at various conversion ratios. A generalized methodology is presented to describe resonant converters with multiple operation modes as a two port which is then used to analyze several operational modes of the presented topology. Experimental results validate the developed theoretical model and demonstrate the superiority of the concept in terms of efficiency (over 10%) and current-sourcing capabilities (over 80%) using a compact 5-W prototype.
Methods and a circuit implementation of audible noise reduction (ANR) in switch-mode converters with variable switching frequency are presented. The audible noise caused by magnetic components is ...reduced by controlling the switching frequency so that it remains above the audible range as the load decreases. This is accomplished by decreasing the peak value of the main switch current pulses in discrete steps until the peak value of the main switch current pulses is decreased to a level that is sufficiently low not to produce unacceptable audible noise. At very light loads and at no load, the ANR circuit can be disabled in order to meet various worldwide standards that limit the maximum input power. The performance of the proposed circuit was experimentally verified in a 90-W single-stage power-factor-correction flyback adapter.
The three basic Switch-Mode PWM converters, buck, boost and buck–boost, have been widely used in computer hardware and industrial applications. There is the need to have models for these converters ...that are compatible with robust control analysis. Uncertainty models for these converters are given in this paper. The resulting models are represented by linear fractional transformations (LFTs) with structured dynamic uncertainties. Therefore, robust stability analysis can be realized using standard
μ-tools. At the end, an illustrative example for a 95 W boost regulator is given which shows the simplicity of the procedure.
Power integrity issues arise at gigahertz (GHz)-range in compact systems integrating fast-switching power devices, such as gallium nitride high-electron mobility transistors. GHz-range current ...measurement techniques must be used in switch-mode converters to assess those issues. State-of-the-art techniques are insufficient due to the inherent limitations of the high-impedance probe in a pick-up coil or the impractical dimensions of the probing apparatus for current-surface probes. This article proposes a novel compact coupled transmission-line-based measurement technique that takes advantage of mutual inductance, allowing the measurement of currents in the GHz-range. A thorough analytical formulation shows that its measurement distortion can be predicted at up to multiple GHz and that the probing pad can be placed at any convenient location on the substrate without affecting the measurement distortion. Measurements with the proposed structure validated with a resistive shunt show that the current in a switch-mode converter can be characterized at up to 1.95 GHz with less than 3-dB measurement distortion, which represents more than 4-dB reduction in amplitude distortion with respect to a resistive shunt technique.
Low power consumption is one of the critical factors for successful Internet of Things (IoT) applications. In such applications, gas sensors have become a main source of power consumption because ...energy conversion efficiency of the microheater is relative over a wide range of operating temperatures. To improve the energy-conversion efficiency of gas-sensor microheaters, this paper proposes integrated switch-mode DC-to-DC power converter technology which we compare with traditional driving methods such as pulse-width modulation and the linear mode. The results indicate that energy conversion efficiency with this proposed method remains over 90% from 150 °C to 400 °C when using a 3.0, 4.2 and 5.0 V power supply. Energy-conversion efficiency increases by 1–74% compared with results obtained using the traditional driving methods, and the sensing film still detects alcohol and toluene at 200 °C and 280 °C, respectively, with high energy conversion efficiency. These results show that the proposed method is useful and should be further developed to drive gas-sensor microheaters, and then integrated into the circuits of the complementary metal-oxide-semiconductor micro electro mechanical systems (CMOS-MEMS).
The main goal of this study was to derive small-signal models of the input characteristics of buck, boost, and flyback converters working in continuous conduction mode (CCM) and discontinuous ...conduction mode (DCM). The models presented in the paper were derived using the separation of variables approach and included the parasitic resistances of all converter components. The paper features a discussion about the limitations of the model accuracy. The presented characteristics were obtained by calculation and verified by measurements. The input characteristics of converters are essential in the design of converters used in Power Factor Correction systems as well as in maximum power point tracking systems (MPPT).
•Operating point stability of power system equipped with high PV penetration is investigated.•Detailed model of the synchronous generator in dq reference frame is considered.•The PV generator is ...interfaced to the power system via two successive stages.•The MPPT is accomplished using a new control strategy.
This paper presents the operating point stability analysis of a Single Machine Infinite Bus (SMIB) power system equipped with high Photovoltaic (PV) penetration. The detailed dynamical model of the synchronous generator in dq reference frame is considered including the dynamics of the damper windings and Automatic Voltage Regulator (AVR). A DC–DC buck–boost switch mode converter is placed as an intermediate stage between the PV array and the inverter. The main function of this implementation is to inject the voltage corresponding to the PV generator Maximum Power Point (MPP) by automatic adjusting its duty cycle. The PV array is designed to provide a maximum output power of about 0.78pu at the full solar irradiance. The nonlinearity of the output characteristics of the PV generator is taken into account. Operating point stability analysis is performed by extracting the eigenvalues of the linearized model around the operating point at different solar irradiances. System response after successive step changes on the synchronous generator input mechanical power at three solar irradiances based on the complete nonlinear dynamical model is investigated. For given synchronous generator input parameters, the response of the system after successive step changes on the solar intensity is addressed. It is found that high PV penetration via DC–DC buck–boost converter and DC–AC inverter is practically possible, experiences a stable operating point and can withstand successive step changes on system parameters in case of practical solar irradiance levels. All numerical simulations are conducted using MATLAB software package by building the code required.
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