One-cycle control of switching converters

A new large-signal nonlinear control technique is proposed to control the duty-ratio d of a switch such that in each cycle the average value of a switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient. One-cycle control rejects power source perturbations in one switching cycle; the average value of the switched variable follows the dynamic reference in one switching cycle; and the controller corrects switching errors in one switching cycle. There is no steady-state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with a constant frequency buck converter have demonstrated the robustness of the control method and verified the theoretical predictions. This new control method is very general and applicable to all types of pulse-width-modulated, resonant-based, or soft-switched switching converters for either voltage or current control in continuous or discontinuous conduction mode. Furthermore, it can be used to control any physical variable or abstract signal that is in the form of a switched variable or can be converted to the form of a switched variable

Dynamics of one-cycle controlled Ćuk converters

One-cycle control is a nonlinear control method. The flow-graph modeling technique is employed to study the large-signal and small-signal dynamic behavior of one-cycle controlled switching converters. Systematic design method for one-cycle control systems is provided with the Ćuk converter as an example. Physical insight is given which explains how one-cycle control achieves instant control without infinite loop gain. Experimental results demonstrate that a Ćuk converter with one-cycle control reflects the power source perturbation in one-cycle and the average of the diode voltage follows the control reference in one cycle

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Comparison of voltage mode soft switching methods for PWM converters

A comparison study was conducted to characterize the loss mechanisms, component stresses, and overall efficiencies of a group of voltage mode soft switching PWM methods including two improvement circuits developed at UCI. All soft switching methods in the selected group allow zero voltage turn-on and turn-off of the main switch and utilize a single auxiliary switch with some resonant components. Advantages and disadvantages were identified for each method. Experimental verification for each soft switching method were provided

Intelligent magnetic amplifier controlled soft-switching method for amplifiers/inverters

This paper proposes a simple, efficient soft-switching method for power switching converters. Soft switching of the DC/AC H-Bridge converter is realized by paralleling two auxiliary switches and a magnetic amplifier with the load. The auxiliary switches are turned on at a predetermined time before the commutation of the main switches. The magnetic amplifier then automatically determines the necessary amount of redirection current to ensure soft switching of all switches under any load conditions. This method requires no expensive sensors or complex control circuitry. It is ideal for class-D audio power amplifiers where the load current is widely changing. Further applications include DC/DC converters, motor drivers, UPS, communication, and space applications where high efficiency, low EMI, and small size are crucial

Intelligent magnetic-amplifier-controlled soft-switching method for amplifiers and inverters

This paper proposes a simple efficient soft-switching method for switching power converters, inverters, and amplifiers. Soft switching of a dc/ac H-bridge converter is realized by paralleling two auxiliary switches and a magnetic amplifier with the load. The auxiliary switches are turned on at a predetermined time before the commutation of the main switches. The magnetic amplifier then automatically deter mines the necessary amount of redirection current to ensure soft switching of all switches under any load conditions. This method requires no expensive sensors or complex control circuitry. It is ideal for class-D audio power amplifiers, where the load current is widely changing. Further applications include dc/dc converters, motor drivers, uninterruptible power supply (UPS), communication, and space applications, where high efficiency, low electromagnetic interference (EMI), and small size are crucial