Abstract: A power controller includes a plurality of power supply output circuits and a multi-level converter connected to the plurality of power supply output circuits to receive a plurality of sets of voltages. The multi-level converter is configured to supply power to a load from a plurality of output terminals. An observer module is operably coupled to the multi-level converter to selectively control multi-level converter common-mode voltage with respect to the plurality of power supply output terminals.

Abstract: A control system having an integrator component that provides an integrator output signal used to control a load, and a method controlling the same includes conditioning the integrator component during a fraction of the period in which it would tend to otherwise wind-up.

Abstract: A method and apparatus for providing electrical power through two terminals to a load wherein a portion of a LC filter circuit is connectable to each of the terminals. A feedback circuit having a sense capacitor is operably couplable to both portions of the LC output filter. The feedback circuit provides a feedback signal when a frequency of AC voltage across the sense capacitor substantially reaches the resonant frequency of the LC output filter so as to actively damp the voltage across the load.

Abstract: A solar-powered grill is assembled from a kit which includes a set of generally flat, foldable components, made of an inexpensive material such as cardboard. The grill includes a flexible, reflective sheet, held by a bottom piece and a pair of side panels, to define a generally parabolic curvature. The side panels define slots for mounting a food item in a region into which sunlight will be focused by the reflective sheet. A pair of tabs forms an aiming device, to insure correct orientation of the body of the grill. The orientation may be altered by placement of the body in a different position on a separate base, or by adjusting the height of one end of the base. The grill may be quickly assembled, without the need for tools, and may be discarded after a single use, or may be disassembled for later re-use.

Abstract: A dual totem (or H-bridge) power stage has four power devices, at least two of which are controlled by pulse width modulation (PWM) control signals to change current paths of the load current flowing through the driven load. A current sensor for measuring the load current includes a transformer having a secondary winding having a number N of turns, and a primary winding. The primary winding has four separate primary winding sections each coupled in series with a different one of the four power devices of the dual totem power stage. Different ones of the four primary winding sections have different numbers of turns such that different turns ratios result between the primary winding and the secondary winding for different current paths, thus generating a modulated signal on the secondary winding. The modulated signal is demodulated for accurate representation or reproduction of the current flowing through the load.

Abstract: A circuit for measuring current flowing through a load driven by a pulse width modulation (PWM) circuit in response to PWM control signals, according to the present invention, includes a transformer having primary and secondary windings, with the primary winding connected to the load. Current cancellation circuitry coupled to the secondary winding is adapted to apply a cancellation current to the secondary winding and to provide an output which is indicative of a level of current through the load. An inverter coupled to the current cancellation circuitry output provides an inverted current cancellation circuitry output. First and second switches selectively couple one of the current cancellation circuitry output and the inverted current cancellation circuitry output to a load current output which provides an output indicative of the level of current through the load during both static and dynamic load current conditions.

Abstract: A high-voltage switching circuit is formed of a series combination of switches, each of which is rated for use at a voltage lower than that of the power supply. The switches are connected in series with inductors, the inductors being magnetically coupled, in an anti-phase manner. A pair of capacitors, having substantially equal values of capacitance, are connected, respectively, in parallel with each series combination of a switch and inductor. The inductors and capacitors together insure that no more than one-half the total voltage of the power supply will ever appear across either switch. The series combination of switches can be used in place of a single switch, and permits the use of switches rated at low voltage to be combined to form an overall switch which works reliably at a higher voltage.

Abstract: An additive substantially improves the adhesion of ordinary sand. The additive includes gelatin, flour or starch. The additive may also include salt, colored sand, and/or white sand. In use, one adds water to the additive, forming the additive into a homogeneous, sticky paste. Then, one combines the paste with ordinary sand, again mixing the paste with the sand to produce a homogeneous mixture. The result is a sand-based composition having improved adhesion, and which therefore can be used to make semi-permanent sand castles or other sculptures.

Abstract: A pulse-width modulated (PWM) circuit applies voltage to a load with high fidelity. The circuit includes switches connected in series with inductors, the inductors being magnetically coupled to other inductors connected to the gates of the switches. The arrangement of inductors and the magnetic coupling causes the turn-on of one switch to assist in the turn-off of the other switch. A pair of diodes connected across some of the inductors assures that the magnetically coupled inductors do not assist the switches to turn on. The result is a circuit which effectively eliminates the problem of "shoot through" current, without providing a "dead time" in the switching scheme, and thus without substantial power losses. The circuit can therefore be used in audio amplification, and in other applications requiring high fidelity.

Abstract: A circuit accurately measures the current flowing in a load which is powered by a pulse-width modulated (PWM) arrangement. The current measurement circuit is transformer-coupled to the load. A first flux cancellation device produces a voltage which tends to reduce the flux in the transformer core to zero. A pair of peak detection circuits determine maximum and minimum voltages at the output of the first flux cancellation device, and another circuit measures the difference between the maximum and minimum voltages. This difference is a voltage which is proportional to the current flowing in the load. A second flux cancellation device includes an integrator which integrates the outputs of the peak detection circuits, and the output of the integrator is fed back to the first flux cancellation device.