The Convergence of Realistic Distributed Load-Balancing Algorithms

We give a general model of partially asynchronous, distributed load-balancing algorithms for the discrete load model in parallel computers, where the processor loads are treated as non-negative integers. We prove that all load-balancing algorithms in this model are finite. This means that all load-balancing algorithms based on this model are guaranteed to reach a stable situation at a certain time (which depends on the particular algorithm) at which no load will be sent from one processor to another. With an additional assumption, we prove that the largest load difference between any two processors, in the final stable situation of the load-balancing algorithms in this model, is upper-bounded by the diameter of the topology.     

HMM–TLP correlation for system-efficient ESD design

A linear correlation between 100 ns TLP and the second HMM peak current was found for several common types of protection devices. A detailed thermal analysis offers a straightforward explanation of the correlation factor in terms of pulse duration. It is found that the thermal effect of the first HMM peak can be ignored. The impact of non-thermal failure mechanisms, e.g. gate oxide breakdown due to an over-voltage, which may limit the validity of the correlation are explored for a complete system, which includes additional components. The results from this investigation are essential for proper application of the System-efficient ESD Design (SEED) methodology.     

Computer-aided small-signal analysis based on impulse response ofDC/DC switching power converters

The paper describes a method for automated small-signal frequency response analysis based on transient response obtained using a general-purpose simulation tool such as simulation program with integrated circuit emphasis (SPICE). The method is based on using the simulation tool to evaluate the converter impulse response. The main advantage of the proposed method as a design verification tool is that frequency responses can be generated efficiently for any converter configuration and any model complexity supported by the general-purpose simulator. Application examples are included to demonstrate very good correlation between the generated responses and experimental data, and to compare the results with predictions of approximate analytical methods. In particular, the method is applied to investigate high-frequency dynamics of pulse width modulation (PWM) converters operating in discontinuous conduction mode, and the results are used to compare and validate several existing analytical modeling approaches     

Nonlinear-carrier control for high-power-factor rectifiers based onup-down switching converters

In this paper, nonlinear-carrier (NLC) control is proposed for high-power-factor rectifiers based on flyback, Cuk, Sepic, and other up-down power converters operated in the continuous conduction mode (CCM). In the NLC controller, the switch duty ratio is determined by comparing a signal proportional to the integral of the switch current with a periodic nonlinear-carrier waveform. The shape of the NLC waveform is determined so that the resulting input-line current follows the input-line voltage, as required for unity power factor rectification. A simple exponential carrier waveform generator is described. Using the NLC controller, input-line voltage sensing, error amplifier in the current-shaping loop, and multiplier/divider circuitry in the voltage feedback loop are eliminated. The simple high-performance controller is well suited for integrated-circuit implementation, Results of experimental verification on a 150 W flyback rectifier are presented     

Optimal Dynamic Management of Exploitation Life of the Mining Machinery: Models with Undefined Interval

The paper is focused on the problem of determining the optimal exploitation life of the long-lasting mining machinery, such as bucket-wheel excavators, excavators with one working element of large capacity, spreaders, self-propelled transporters, conveyor belts and similar machinery. A concept of approach is presented, and an application of the dynamic model with the undefined interval is given by using the example of the bucket-wheel excavator. The paper concludes with observations and assessments regarding the subject matter.     

Constant-frequency control of quasi-resonant converters

An additional independent control needed to eliminate the undesirable variable switching frequency of quasi-resonant (QR) converters is obtained by replacing the output rectifier by an active switch. The concept is applicable to all classes of converters. Compared to QR converters with conventional switch realization, constant-frequency quasi-resonant (CF-QR) converters exhibit the same type of switching transitions and similar switch voltage and current stresses. Advantages of CF-QR converters are not restricted to the constant-frequency control. In all classes, operation at zero load is possible, so that the available load range is unlimited. The range of attainable, conversion ratios is significantly extended in the classes of zero-voltage quasi-square-wave (CF-ZV-QSW) and zero-voltage multiresonant (CF-ZV-MR) topologies. A practical design example of a 25 W CF-ZV-MR buck converter is constructed and evaluated. The converter operates at 2 MHz from zero load to full load, with a full-load efficiency of 83%. Simple duty ratio control is used to maintain the output voltage constant for all loads. The circuit is inherently immune to the short-circuit condition at the output. Disadvantages of CF-QR converters are the increased gate-drive losses and increased complexity of the power stage and the control circuitry     

Analysis and design of a low-stress buck-boost converter in universal-input PFC applications

In converters for power-factor-correction (PFC), the universal-input capability, i.e., the ability to operate from any ac line voltage world-wide, comes with a heavy penalty in terms of component stresses and losses, and with restrictions on the dc output voltage. In this paper, we propose a new two-switch topology, boost-interleaved buck-boost (BoIBB) converter, which can offer significant performance improvements over single-switch buck-boost converters (including flyback, SEPIC, or Cuk topologies) or other two-switch buck-boost converters in universal-input PFC applications. The paper presents an analysis of the converter operation and component stresses, as well as design guidelines. High efficiency (over 93%) throughout the universal-input ac line voltage range is demonstrated on an experimental 100-W, 200-V dc output, universal-input BOIBB PFC rectifier.     

A digitally controlled DC/DC converter for an RF power amplifier

This paper describes design and implementation of a digitally controlled dc/dc converter that provides a dynamically adjustable supply voltage for a radio frequency power amplifier (RFPA). The techniques employed in the design include a combination of constant-frequency continuous conduction mode (CCM) and a variable-frequency discontinuous conduction mode to achieve very high converter efficiency over a wide range of output power levels. The variable-frequency converter control is accomplished using a current-estimator circuit, which eliminates the need for current sensing. A field-programmable gate array (FPGA)-based digital controller implementation allows programmability of the mode transition and other controller parameters. In the complete experimental system, which consists of the digitally controlled dc/dc converter and a class-E RFPA operating at 10GHz, experimental results show that the overall system efficiency is significantly improved over a wide range of RFPA output power levels.     

A planar 4.5-GHz DC-DC power converter

In this paper, we present two DC-DC converters that operate at a microwave frequency. The first converter consists of a class-E switched-mode microwave amplifier, which performs the DC-AC conversion, and two half-wave diode rectifier outputs. The class-E MESFET amplifier has a minimum power-added efficiency of 86%, corresponding drain efficiency of 95%, and 120 mW of output power at 4.5 GHz. The diode rectifier has a maximum conversion efficiency of 98% and an overall efficiency of 83%. The second converter consists of a high-efficiency class-E oscillator and a diode rectifier. The class-E oscillator has a maximum efficiency of 57% and maximum output power of 725 mW. The DC-DC converter is planar and compact, with no magnetic components, and with a maximum overall DC-DC conversion efficiency of 64% for a DC input of 3 V, and the output voltage across a 87-Ω load of 2.15 V