Issa Batarseh

A computing device may include a display, a memory to store electronic textbook data comprising a plurality of different images associated with at least one location within the electronic textbook data, a user input device, and a processor coupled to the display, the memory, and the user input device. The processor may be configured to display the electronic textbook data with a primary image from among the plurality of different images at the at least one location on the display, and… Show more

A computing device may include a display, a memory to store electronic textbook data comprising a plurality of different images associated with at least one location within the electronic textbook data, a user input device, and a processor coupled to the display, the memory, and the user input device. The processor may be configured to display the electronic textbook data with a primary image from among the plurality of different images at the at least one location on the display, and selectively replace the primary image with at least one secondary image from among the plurality of different images at the at least one location on the display based upon the user input device. Show less

Abstract
A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has… Show more

Abstract
A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has first and second primary windings coupled to the first and second inverters. The transformer module further includes a secondary winding coupled to first primary winding, the second primary winding, and the AC power grid. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled. Show less

A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM… Show more

A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit. Show less

A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control… Show more

A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control inputs of the first, second and third phase circuitry, where the drivers are configured for receiving phase skipping control signals from the controller and outputting mode selection signals configured to dynamically select an operating mode for the DC/AC inverter from a Normal Control operation and a Phase Skipping Control operation which have different power injection patterns through the first, second and third phase circuitry depending upon the power level. Show less

A computing device may include a display, a memory to store electronic book data having a plurality of different content layers each associated with a different content difficulty level, and a processor coupled to the display and the memory. The processor may determine a selected content difficulty level for viewing of the electronic book data, and display on the display the respective content layer of the electronic book data associated with the selected content difficulty level.

A computer system may include a plurality of computing devices each including a display, a memory to store electronic book data comprising at least one configurable problem to be solved, and a processor coupled to the display and the memory. The processor may display the electronic book data with the at least one configurable problem on the display, and apply a changeable seed value to the at least one configurable problem to change an answer associated with the at least one configurable… Show more

A computer system may include a plurality of computing devices each including a display, a memory to store electronic book data comprising at least one configurable problem to be solved, and a processor coupled to the display and the memory. The processor may display the electronic book data with the at least one configurable problem on the display, and apply a changeable seed value to the at least one configurable problem to change an answer associated with the at least one configurable problem. Show less

A multi-transformer LLC (resonant) power converter having at least two transformers including a first T.sub.1 and a second transformer T.sub.2 in series includes a switch network configured for receiving input power including a first and second switched node. Resonant circuitry is coupled between the first and second switched node including a series combination of an inductor, a capacitor, a primary winding of T.sub.1 and a primary winding of a T.sub.2. At least one switch is operable for… Show more

A multi-transformer LLC (resonant) power converter having at least two transformers including a first T.sub.1 and a second transformer T.sub.2 in series includes a switch network configured for receiving input power including a first and second switched node. Resonant circuitry is coupled between the first and second switched node including a series combination of an inductor, a capacitor, a primary winding of T.sub.1 and a primary winding of a T.sub.2. At least one switch is operable for providing a first mode that includes T.sub.2 in the resonant circuitry and a second mode that excludes T.sub.2 from the resonant circuitry. Secondary windings of T.sub.2 and T.sub.1 are connected electrically in parallel for driving an output capacitor (Co) through respective rectifiers which provide conversion from AC to DC. Show less

A method of maximum power point tracking (MPPT) uses an MPPT algorithm to determine a switching frequency for a resonant power converter, including initializing by setting an initial boundary frequency range that is divided into initial frequency sub-ranges bounded by initial frequencies including an initial center frequency and first and second initial bounding frequencies. A first iteration includes measuring initial powers at the initial frequencies to determine a maximum power initial… Show more

A method of maximum power point tracking (MPPT) uses an MPPT algorithm to determine a switching frequency for a resonant power converter, including initializing by setting an initial boundary frequency range that is divided into initial frequency sub-ranges bounded by initial frequencies including an initial center frequency and first and second initial bounding frequencies. A first iteration includes measuring initial powers at the initial frequencies to determine a maximum power initial frequency that is used to set a first reduced frequency search range centered or bounded by the maximum power initial frequency including at least a first additional bounding frequency. A second iteration includes calculating first and second center frequencies by averaging adjacent frequent values in the first reduced frequency search range and measuring second power values at the first and second center frequencies. The switching frequency is determined from measured power values including the second power values. Show less

A photovoltaic (PV)-based AC module (module) includes a PV panel and a three-phase micro-inverter system attached to or integrated directly into the PV panel including a DC/AC inverter stage including first, second and third phase circuitry each having a plurality of semiconductor power switches. A first, second and third control input driver are coupled to drive control inputs of the plurality of semiconductor power switches in the first, second and third phase circuitry, respectively. The… Show more

A photovoltaic (PV)-based AC module (module) includes a PV panel and a three-phase micro-inverter system attached to or integrated directly into the PV panel including a DC/AC inverter stage including first, second and third phase circuitry each having a plurality of semiconductor power switches. A first, second and third control input driver are coupled to drive control inputs of the plurality of semiconductor power switches in the first, second and third phase circuitry, respectively. The module can include a control unit coupled to drive the first, second and third control input driver, and a transceiver and antenna coupled to the control unit for implementing wireless communications. Show less

Interactive and real time web-based electrical circuit symbolic solvers and simulators. The invention includes an interactive and innovative graphical user interface (GUI) for creating circuit schematics and generating netlists, circuits symbolic solving and instant simulated solutions, their systems and methods. Users such as students can use GUI interfaces to remotely access a remote server controlled by educational institutions such as universities, or electronic book publishers, in order to… Show more

Interactive and real time web-based electrical circuit symbolic solvers and simulators. The invention includes an interactive and innovative graphical user interface (GUI) for creating circuit schematics and generating netlists, circuits symbolic solving and instant simulated solutions, their systems and methods. Users such as students can use GUI interfaces to remotely access a remote server controlled by educational institutions such as universities, or electronic book publishers, in order to draw, symbolically solve, and instantly simulate electrical circuits. Show less

A method for controlling a photovoltaic (PV) panel in a PV system including a computing device that provides motor control signals and implements an iterative adaptive control (IAC) algorithm for adjusting an angle of the PV panel. The IAC algorithm relates P at a current time k (P(k)), an elevation angle of the PV panel at k (θS (k)), P after a next step (P(k+1)) and an elevation angle of the PV panel at k+1 (θS (k+1)). The algorithm generates a perturbed power value P(k+1) to provide a power… Show more

A method for controlling a photovoltaic (PV) panel in a PV system including a computing device that provides motor control signals and implements an iterative adaptive control (IAC) algorithm for adjusting an angle of the PV panel. The IAC algorithm relates P at a current time k (P(k)), an elevation angle of the PV panel at k (θS (k)), P after a next step (P(k+1)) and an elevation angle of the PV panel at k+1 (θS (k+1)). The algorithm generates a perturbed power value P(k+1) to provide a power perturbation to P(k), and calculates θS (k+1) using P(k+1). The motor control signals cause the motor to position the PV panel to achieve θS (k+1). A change in P resulting from the positioning is compared to a predetermined change limit, and only if the change in P is ≧ the change limit, again sensing P, and repeating the generating, calculating and positioning. Show less

Interactive electronic book operating systems and methods for displaying and allowing customization of content of scientific, engineering and other technical and professional digital books. The display screen can include icons for forward and backward page turning, generating of dynamic indexing and tables of contents, bookmarking, color themes, floating pages, highlighting, adding sticky notes, hiding selected content on the pages, quizzing the reader, lecturing the reader, tutoring the… Show more

Interactive electronic book operating systems and methods for displaying and allowing customization of content of scientific, engineering and other technical and professional digital books. The display screen can include icons for forward and backward page turning, generating of dynamic indexing and tables of contents, bookmarking, color themes, floating pages, highlighting, adding sticky notes, hiding selected content on the pages, quizzing the reader, lecturing the reader, tutoring the reader, showing the reader additional designs and practical relevance, and allowing the instructor to generate uniform seed numbers for problems and designs and/or allowing the instructor to generate random seed values for problems and designs. Show less

A system controller for position controlling a photovoltaic (PV) panel in a PV system including a power sensor sensing output power (P), and a motor for positioning the PV panel. The system controller includes a computing device having memory that provides motor control signals and implements an iterative adaptive control (IAC) algorithm stored in the memory for adjusting an angle of the PV panel. The IAC algorithm includes an iterative relation that relates P at current time k (P(k)), its… Show more

A system controller for position controlling a photovoltaic (PV) panel in a PV system including a power sensor sensing output power (P), and a motor for positioning the PV panel. The system controller includes a computing device having memory that provides motor control signals and implements an iterative adaptive control (IAC) algorithm stored in the memory for adjusting an angle of the PV panel. The IAC algorithm includes an iterative relation that relates P at current time k (P(k)), its elevation angle at k (θs (k)), P after a next step (P(k+1)) and its elevation angle at k+1 (θs (k+1)). The IAC algorithm generates a perturbed power value P(k+1) to provide a power perturbation to P(k), and calculates a position angle θS (k+1) of the PV panel using the perturbed power value. The motor control signals from the computing device cause the motor to position the PV panel to achieve θS (k+1). Show less

A system controller for position controlling a photovoltaic (PV) panel in a PV system including a power sensor sensing output power (P), and a motor for positioning the PV panel. The system controller includes a computing device having memory that provides motor control signals and implements an iterative adaptive control (IAC) algorithm stored in the memory for adjusting an angle of the PV panel. The IAC algorithm includes an iterative relation that relates P at current time k (P(k)), its… Show more

A system controller for position controlling a photovoltaic (PV) panel in a PV system including a power sensor sensing output power (P), and a motor for positioning the PV panel. The system controller includes a computing device having memory that provides motor control signals and implements an iterative adaptive control (IAC) algorithm stored in the memory for adjusting an angle of the PV panel. The IAC algorithm includes an iterative relation that relates P at current time k (P(k)), its elevation angle at k (θs (k)), P after a next step (P(k+1)) and its elevation angle at k+1 (θs (k+1)). The IAC algorithm generates a perturbed power value P(k+1) to provide a power perturbation to P(k), and calculates a position angle θS (k+1) of the PV panel using the perturbed power value. The motor control signals from the computing device cause the motor to position the PV panel to achieve θS (k+1). Show less

Interactive and real time web-based electrical circuit symbolic solvers and simulators. The invention includes an interactive and innovative graphical user interface (GUI) for creating circuit schematics and generating netlists, circuits symbolic solving and instant simulated solutions, their systems and methods. Users such as students can use GUI interfaces to remotely access a remote server controlled by educational institutions such as universities, or electronic book publishers, in order to… Show more

Interactive and real time web-based electrical circuit symbolic solvers and simulators. The invention includes an interactive and innovative graphical user interface (GUI) for creating circuit schematics and generating netlists, circuits symbolic solving and instant simulated solutions, their systems and methods. Users such as students can use GUI interfaces to remotely access a remote server controlled by educational institutions such as universities, or electronic book publishers, in order to draw, symbolically solve, and instantly simulate electrical circuits. Show less

A method for balancing power distribution in a direct current to direct current (DC to DC) power-conversion system is provided. The power-conversion system includes a plurality of channels that are connected to a load. The channels are also connected to corresponding power sources. The method, at a first channel, includes obtaining a first power, which is the maximum power of the power source connected to the first channel. Further, the method includes computing a reference power based on the… Show more

A method for balancing power distribution in a direct current to direct current (DC to DC) power-conversion system is provided. The power-conversion system includes a plurality of channels that are connected to a load. The channels are also connected to corresponding power sources. The method, at a first channel, includes obtaining a first power, which is the maximum power of the power source connected to the first channel. Further, the method includes computing a reference power based on the power output of the channels. Furthermore, the method includes outputting the reference power when the first power is greater than or equal to the reference power, and outputting the first power when the first power is less than the reference power. Show less

Methods, systems and apparatus for a controller for fast transient response, the controller including a linear compensation circuit for controlling output voltage during steady state operation and a non-linear control circuit to generate a non-linear signal during transient periods, only a first pulse of the non-linear signal is injected during each transient period. The combination linear and non-linear control provides stability and reduces delay times for fast transient response. The… Show more

Methods, systems and apparatus for a controller for fast transient response, the controller including a linear compensation circuit for controlling output voltage during steady state operation and a non-linear control circuit to generate a non-linear signal during transient periods, only a first pulse of the non-linear signal is injected during each transient period. The combination linear and non-linear control provides stability and reduces delay times for fast transient response. The non-linear control circuit includes a step up and a step down non-linear control circuit for producing the non-linear signal with a short delay time when the load voltage is less or greater than the reference voltage. An embodiment includes an adaptive circuit or generating a current signal dependent on the load current, the current signal is combined with the output voltage to reduce the difference between the reference and output voltages. Show less

A DC-to-DC converter having a transformer with a primary and a tapped secondary, two serial output filter inductors connected parallel with the secondary, a center output filter inductor connected between the secondary tap and serial output inductors, two serially connected switches connected in parallel with the two output inductors for receiving a signal to control operation of the switches during steady state and an output load connected between the serial connection of the serial output… Show more

A DC-to-DC converter having a transformer with a primary and a tapped secondary, two serial output filter inductors connected parallel with the secondary, a center output filter inductor connected between the secondary tap and serial output inductors, two serially connected switches connected in parallel with the two output inductors for receiving a signal to control operation of the switches during steady state and an output load connected between the serial connection of the serial output inductors and serial switching devices. The transformer primary side connected with double-ended primary-side topologies. The transformer secondary and output filers configured to form a current tripler rectifier, current quadtupler rectifier or current N-tuper rectifier. The output filter inductors evenly share output current resulting in reduction of current and thermal stress during high current application and the rectification topology has simple driving for synchronous rectifier application without increasing complexity of control and operation of primary-side topologies. Show less

Apparatus, methods, system and devices for providing a high efficiency parallel post regulator for a wide range input DC/DC converter. The wide input range DC/DC converter achieves zero-voltage-switching in the primary side switches in full range load due to 0.5 duty cycle of the operation at full load. The DC/DC converter reduces voltage stresses across main rectifiers, has a smaller conduction losses compared with conventional post regulators and the requirement of input and output filters is… Show more

Apparatus, methods, system and devices for providing a high efficiency parallel post regulator for a wide range input DC/DC converter. The wide input range DC/DC converter achieves zero-voltage-switching in the primary side switches in full range load due to 0.5 duty cycle of the operation at full load. The DC/DC converter reduces voltage stresses across main rectifiers, has a smaller conduction losses compared with conventional post regulators and the requirement of input and output filters is significantly reduced due to the filtered waveforms produced. Show less

A direct current to direct current (DC-to-DC) converter having an active transient voltage compensator (ATVC) coupled with the DC-to-DC converter output terminal to improve a fast transient response of the DC-to-DC converter. The active transient voltage compensator compensates the DC output only during transient operation The ATVC includes a transformer for reducing the ATVC current stresses to improve the compensator efficiency and injecting, absorbing high slew rate current, and a controller… Show more

A direct current to direct current (DC-to-DC) converter having an active transient voltage compensator (ATVC) coupled with the DC-to-DC converter output terminal to improve a fast transient response of the DC-to-DC converter. The active transient voltage compensator compensates the DC output only during transient operation The ATVC includes a transformer for reducing the ATVC current stresses to improve the compensator efficiency and injecting, absorbing high slew rate current, and a controller circuit for controlling ATVC operation in steady state and normal operation in transients. During step-up load the ATVC operates as a buck converter and during step-down load, the ATVC operates as a boost converter while the main converter operates at low switching frequency for good efficiency. Show less

Apparatus, methods system and devices for using alternated duty cycle control to achieve soft-switching for at least one switch of the two half-bridge switches. When soft-switching can be only achieved for one switch, alternated duty cycle control alternates the soft-switching between the two switches so that each switch is soft-switched during half of the time and hard-switched during the other half, keeping equal power losses distribution between the switches. When alternated duty cycle… Show more

Apparatus, methods system and devices for using alternated duty cycle control to achieve soft-switching for at least one switch of the two half-bridge switches. When soft-switching can be only achieved for one switch, alternated duty cycle control alternates the soft-switching between the two switches so that each switch is soft-switched during half of the time and hard-switched during the other half, keeping equal power losses distribution between the switches. When alternated duty cycle control is used, any asymmetry in the duty cycle does not cause asymmetric components stresses or transformer DC bias. Show less

A power converter includes a first transformer that has a primary winding and a secondary winding. The secondary winding is coupled to a first secondary side. A second transformer has a primary winding and a secondary winding. The secondary winding is coupled to a second secondary side. The primary windings of the first and second transformers are coupled in parallel to a primary side through respective windings of a transformer that has inverse coupled windings. The secondary windings of the… Show more

A power converter includes a first transformer that has a primary winding and a secondary winding. The secondary winding is coupled to a first secondary side. A second transformer has a primary winding and a secondary winding. The secondary winding is coupled to a second secondary side. The primary windings of the first and second transformers are coupled in parallel to a primary side through respective windings of a transformer that has inverse coupled windings. The secondary windings of the first and second transformer are coupled in parallel. The second secondary side is interleaved with the first secondary side. Show less

A coupled-inductor current-doubler topology for a power converter has first and second rectifiers and first and second coupled inductors. Each coupled inductor has a main inductor inductively coupled with a secondary inductor. The secondary inductor of the first coupled inductor is coupled in series with one of the first and second rectifiers and the secondary inductor of the second coupled inductor coupled in series with the other one of the first and second rectifiers.

A high performance single stage Power Factor Correction (PFC) converter with tight output voltage regulation and a very simple circuit to carry out those functions, which means its cost is lower than its counterparts. Two basic flyback circuits include a simple control circuit. For the hard switching circuit, only one switch is used to achieve low cost; for the soft switching scheme, one auxiliary switch is added to get higher efficiency and smaller size. There are two power flow paths… Show more

A high performance single stage Power Factor Correction (PFC) converter with tight output voltage regulation and a very simple circuit to carry out those functions, which means its cost is lower than its counterparts. Two basic flyback circuits include a simple control circuit. For the hard switching circuit, only one switch is used to achieve low cost; for the soft switching scheme, one auxiliary switch is added to get higher efficiency and smaller size. There are two power flow paths, resulting in part power processed by an active switch only once to reduce the current stress and improve the efficiency. A direct current (DC) bus voltage will be limited to the peak value of input voltage. The maximum DC bus voltage will be less than 400 and a single commercial capacitor can be used for universal voltage stress under light load condition. Show less

A duty-cycle-shifted pulse-width modulation controlled half-bridge zero-voltage switching DC—DC converter has a primary side, a secondary side and a transformer coupling the primary side to the secondary side. The primary side has first and second primary switches coupled to a primary winding of the transformer and an auxiliary branch having one side coupled to a junction of the first and second primary switches and a second side coupled to common. The auxiliary branch includes a grounded… Show more

A duty-cycle-shifted pulse-width modulation controlled half-bridge zero-voltage switching DC—DC converter has a primary side, a secondary side and a transformer coupling the primary side to the secondary side. The primary side has first and second primary switches coupled to a primary winding of the transformer and an auxiliary branch having one side coupled to a junction of the first and second primary switches and a second side coupled to common. The auxiliary branch includes a grounded auxiliary switch that is switched on when one of the first and second primary switches is on to trap leakage inductance energy of the transformer when that primary switch is turned off and thereafter switched off to release the trapped leakage inductance energy to provide a zero voltage switching condition for the other primary switch. The one of the first and second primary switches that is on when the auxiliary switch is switched on may be controlled with duty-cycle-shifted pulse width modulation to provide a zero current switching condition for that primary switch. Show less

A method and system of controlling half-bridge DC—DC converters to achieve Zero Voltage Switching (ZVS) for at least one of the switches. The soft-switching half-bridge DC—DC converter system includes soft-switching for all switches by adding an additional branch with a switch and a diode across the primary side of an isolation transformer and by applying a Duty-Cycle Shifted PWM Control

Power Factor Correction (PFC) “flyboost” cell, with a transformer having primary winding connected to input power and secondary winding connected to output rectifier, which has both functions of a flyback transformer and boost inductor. Combining the flyboost cell with DC/DC conversion cells, forms a single-stage PFC converters. Both cells share one main switch and one controller. Letting the flyboost cell operate at Discontinuous Conduction Mode, requires a simple control for high power… Show more

Power Factor Correction (PFC) “flyboost” cell, with a transformer having primary winding connected to input power and secondary winding connected to output rectifier, which has both functions of a flyback transformer and boost inductor. Combining the flyboost cell with DC/DC conversion cells, forms a single-stage PFC converters. Both cells share one main switch and one controller. Letting the flyboost cell operate at Discontinuous Conduction Mode, requires a simple control for high power factor. Through flyboost cell, part of output power is processed once by main switch, and is referred to as direct power transfer (DPT), which will significantly improve efficiency. The flyboost cell will automatically limit the DC bus voltage through flyboost transformer turn ratio. The converters are suitable for universal voltage applications. Show less

Abstract
A new innovative concept in AC/DC cell that transfers energy to the output side directly from the input line, rather than from the storage capacitor in power factor correction (PFC) cell during the period that the line voltage exceeds a preset value. The new concept is based on providing additional winding coupled to the DC/DC transformer connected to the rectified input side to provide a path for the energy transfer from the line to transfer to the output directly (Boost cell) or… Show more

Abstract
A new innovative concept in AC/DC cell that transfers energy to the output side directly from the input line, rather than from the storage capacitor in power factor correction (PFC) cell during the period that the line voltage exceeds a preset value. The new concept is based on providing additional winding coupled to the DC/DC transformer connected to the rectified input side to provide a path for the energy transfer from the line to transfer to the output directly (Boost cell) or to be stored in the output transformer (Flyback cell). Show less

A multiphase DC/DC converter with voltage-mode hysteretic control and instantaneous current sharing functionality method and circuit. The disclosed method and circuit provides independent output voltage regulation and phases current regulation for the converter in two separate loops; one of which is concerned with voltage regulation preferably hysteretic regulation and the other which is concerned with phase current regulation. In one embodiment, each phase in the DC/DC converter is driven by a… Show more

A multiphase DC/DC converter with voltage-mode hysteretic control and instantaneous current sharing functionality method and circuit. The disclosed method and circuit provides independent output voltage regulation and phases current regulation for the converter in two separate loops; one of which is concerned with voltage regulation preferably hysteretic regulation and the other which is concerned with phase current regulation. In one embodiment, each phase in the DC/DC converter is driven by a frequency divided signal derived directly from the output voltage ripple so that each phase has a switching frequency equal to the output voltage ripple frequency divided by the number of paralleled phase. In another embodiment, only the phase that carries the smallest current among a set of phases will be turned ON in each switching cycle to supply power to the output, avoiding multiple switching. Current sharing and regulation is achieved without shortening the ON time and with no multiple switching in any cycle. Show less

One-stage power factor correction (PFC) with output electrical isolation. Two types of PFC converters are proposed here: 1) Multi stage capacitive-switching network low voltage PFC converter and 2) two-switch soft switching PFC converters. This resulted in a near unity power factor AC-DC converter with low voltage output. The second converter uses the power switch in combination with a grounded auxiliary switch to produce soft-switching converter to operate in high switching frequencies. Due to… Show more

One-stage power factor correction (PFC) with output electrical isolation. Two types of PFC converters are proposed here: 1) Multi stage capacitive-switching network low voltage PFC converter and 2) two-switch soft switching PFC converters. This resulted in a near unity power factor AC-DC converter with low voltage output. The second converter uses the power switch in combination with a grounded auxiliary switch to produce soft-switching converter to operate in high switching frequencies. Due to its simplified power stage and control circuit, this converter presents a variety of benefits including better efficiency (87%), lower cost, higher reliability, increased operating frequencies into the hundreds of kilo-hertz range and low operating voltages of less than 5 volts. With PSPICE simulation and experimental results, a measured power factor of 0.99 was obtained by the single switch converter. Show less

floppy disk cartridge adapter having a removable coin shaped memory disk. The 3½ inch size cartridge adapter can fit into conventional personal computer disk drives. The small coin shaped magnetic disk has a diameter of approximately 1 inch, and can be easily snapped into and removed from the cartridge adapter. The coin disk fits on a spindle that is side by side to the floating drive plate used in regular 3½ inch floppy diskettes. The spindle can be attached by various drive systems to rotate… Show more

floppy disk cartridge adapter having a removable coin shaped memory disk. The 3½ inch size cartridge adapter can fit into conventional personal computer disk drives. The small coin shaped magnetic disk has a diameter of approximately 1 inch, and can be easily snapped into and removed from the cartridge adapter. The coin disk fits on a spindle that is side by side to the floating drive plate used in regular 3½ inch floppy diskettes. The spindle can be attached by various drive systems to rotate simultaneously with the rotating drive plate. One version is belt driven, another has the coin disk snap onto a spindle supported wheel whose sides frictionally rub against the drive plate wheel, and a third version has the coin disk snap onto the spindle supported gear wheel whose sides contain teeth which mateably engage like side teeth on the drive plate wheel. The coin disk can alternatively be inserted into a separate casing having a spring loaded shutter so that the conventional disk drive being used can access the magnetic sides of the coin disk by sliding the shutter. When removed from the cartridge adapter, the disk can be inserted into a small clip retainer which has a paper clip edge allowing the coin shaped disk to be portably mounted on papers, cardboard, clipboards and the like. Show less

A floppy disk cartridge adapter having a removable coin shaped memory disk. The 3 & 1/2 inch size cartridge adapter can fit into conventional personal computer disk drives. The small coin shaped magnetic disk has a diameter of approximately 1 inch, and can be easily snapped into and removed from the cartridge adapter. The coin disk fits on a spindle that is side by side to the floating drive plate used in regular 3 & 1/2 inch floppy diskettes. The spindle can be attached by various drive… Show more

A floppy disk cartridge adapter having a removable coin shaped memory disk. The 3 & 1/2 inch size cartridge adapter can fit into conventional personal computer disk drives. The small coin shaped magnetic disk has a diameter of approximately 1 inch, and can be easily snapped into and removed from the cartridge adapter. The coin disk fits on a spindle that is side by side to the floating drive plate used in regular 3 & 1/2 inch floppy diskettes. The spindle can be attached by various drive systems to rotate simultaneously with the rotating drive plate. One version is belt driven, another has the coin disk snap onto a spindle supported wheel whose sides frictionally rub against the drive plate wheel, and a third version has the coin disk snap onto the spindle supported gear wheel whose sides contain teeth which mateably engage like side teeth on the drive plate wheel. The coin disk can alternatively be inserted into a separate casing having a spring loaded shutter so that the conventional disk drive being used can access the magnetic sides of the coin disk by sliding the shutter. When removed from the cartridge adapter, the disk can be inserted into a small clip retainer which has a paper clip edge allowing the coin shaped disk to be portably mounted on papers, cardboard, clipboards and the like. Show less

One-stage power factor correction (PFC) with output electrical isolation. The converter has a configuration of combining a boost circuit and a forward circuit in one power stage. To relieve the voltage spike caused by the leakage inductance of the power transformer, two bulk storage capacitors are used. The same power switch is shared by the PFC circuit and the power conversion circuit. Due to its simplified power stage and control circuit, this converter presents a better efficiency (87%)… Show more

One-stage power factor correction (PFC) with output electrical isolation. The converter has a configuration of combining a boost circuit and a forward circuit in one power stage. To relieve the voltage spike caused by the leakage inductance of the power transformer, two bulk storage capacitors are used. The same power switch is shared by the PFC circuit and the power conversion circuit. Due to its simplified power stage and control circuit, this converter presents a better efficiency (87%), lower cost and higher reliability. Detailed steady state analysis results show this novel converter has both good power factor correction and excellent regulation capabilities. With PSPICE simulation and experimental results, a measured power factor of 0.99 was obtained by this single switch converter. Show less

A modified DC-to-AC power converter accomplishes power transfer to a load with electrical isolation, zero-voltage and zero-current switching, using a transformer core resetting mechanism. The power converter contains two switching devices, a main device connected in parallel and a secondary device connected in series with a transformer primary winding. A secondary winding of the transformer is connected through a two-port resonant link circuit to a resistive load. Zero-voltage switching and… Show more

A modified DC-to-AC power converter accomplishes power transfer to a load with electrical isolation, zero-voltage and zero-current switching, using a transformer core resetting mechanism. The power converter contains two switching devices, a main device connected in parallel and a secondary device connected in series with a transformer primary winding. A secondary winding of the transformer is connected through a two-port resonant link circuit to a resistive load. Zero-voltage switching and proper transformer-core resetting are achieved from the resonance that exists between the parasitic capacitance of the secondary switching device and the magnetization inductance of the transformer. A transformer leakage inductance facilitates zero-current switching; thus, reducing the turn-on switching loss in the conventional main switching device. The switching converter contains a lossless clamping circuit, to limit the voltage stresses across both of the power switching devices to the reflected output voltage appearing across the primary. Show less

A modified boost converter accomplishes power transfer to a load with an electrical isolation, a zero-voltage and a zero-current switching, a transformer core resetting mechanism, and component stresses identical to those in the conventional boost converters. The power converter contains two switching devices, a main one connected in parallel and a secondary one connected in series with a transformer primary winding. A secondary winding of the transformer is connected through an output… Show more

A modified boost converter accomplishes power transfer to a load with an electrical isolation, a zero-voltage and a zero-current switching, a transformer core resetting mechanism, and component stresses identical to those in the conventional boost converters. The power converter contains two switching devices, a main one connected in parallel and a secondary one connected in series with a transformer primary winding. A secondary winding of the transformer is connected through an output rectifier to the load. Zero-voltage switching and proper transformer-core resetting are achieved from the resonance that exists between the parasitic capacitance of the secondary switching device and the magnetization inductance of the transformer. A transformer leakage inductance facilitates zero-current switching; thus, reducing the recovery time and current in the output rectifier, and the turn-on switching loss in the conventional main switching device. The switching converter contains a lossless clamping circuit, to limit the voltage stresses across both of the power switching devices to the reflected output voltage appearing across the primary. Show less

A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM… Show more

A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit. Show less

A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control… Show more

A power inverter includes a DC/AC inverter having first, second and third phase circuitry coupled to receive power from a power source. A controller is coupled to a driver for each of the first, second and third phase circuitry (control input drivers). The controller includes an associated memory storing a phase skipping control algorithm, wherein the controller is coupled to receive updating information including a power level generated by the power source. The drivers are coupled to control inputs of the first, second and third phase circuitry, where the drivers are configured for receiving phase skipping control signals from the controller and outputting mode selection signals configured to dynamically select an operating mode for the DC/AC inverter from a Normal Control operation and a Phase Skipping Control operation which have different power injection patterns through the first, second and third phase circuitry depending upon the power level Show less

The present invention is directed to a system configured to be connected to an AC power grid having at least one AC phase signal. The system includes at least one inverter module comprising a first inverter having a plurality of first switch elements coupled to a direct current (DC) voltage and actuated in accordance with a first set of control signals based on the at least one AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. The at… Show more

The present invention is directed to a system configured to be connected to an AC power grid having at least one AC phase signal. The system includes at least one inverter module comprising a first inverter having a plurality of first switch elements coupled to a direct current (DC) voltage and actuated in accordance with a first set of control signals based on the at least one AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. The at least one inverter module further comprises a second inverter including a plurality of second switch elements coupled to the DC voltage and actuated in accordance with a second set of control signals phase delayed with respect to the first set of control signals. The second switching inverter providing a second voltage signal having the predetermined harmonic components. At least one transformer module includes at least one first primary winding coupled to the first inverter and at least one second primary winding coupled to the second inverter. The transformer module further includes at least one secondary winding coupled to the at least one first primary winding, the at least one second primary winding and the AC power grid for each at least one AC phase signal. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled. Show less

A collaborative learning system, method and computer program product permits live, real time interaction between the audience and a presenter in a controlled learning environment. The collaborative learning system, method and computer program product provides a learning process that facilitates the transfer of expertise and knowledge using “push” technology. The system includes a presenter subsystem, a backbone subsystem and an audience subsystem. The process includes pre-event, event and… Show more

A collaborative learning system, method and computer program product permits live, real time interaction between the audience and a presenter in a controlled learning environment. The collaborative learning system, method and computer program product provides a learning process that facilitates the transfer of expertise and knowledge using “push” technology. The system includes a presenter subsystem, a backbone subsystem and an audience subsystem. The process includes pre-event, event and post-event stages. During the pre-event stage, content is created and optimized, and the producer “coaches” the presenter. During the event stage, the presenter and the producer, using the presenter subsystem, push the event material to the audience located remotely at the audience subsystem via the backbone subsystem. The event materials may comprise slides, streaming audio/video and interactive answers to questions and responses to audience feedback. During the post-event stage, follow-up materials are prepared and presented to the audience, case studies are analyzed and the results are presented to the audience, and the event and related documents are “chunked” and archived for later retrieval on demand via a microsite. Show less