Abstract: A multi-coil inductor includes a plurality of stacked inductor units. Each of the inductor units comprises: a magnetic core in which a magnetic path is formed; and a plurality of coils which are wound around the magnetic core to form at least one winding pair. Wherein a part of the magnetic path between the adjacent inductor units is shared. In the present invention, the leakage inductance is controlled and the maybe magnetic saturation of magnetic core avoided by adjusting series and parallel connections among the coils.

Abstract: Critical-mode soft-switching techniques for a power converter are described. In one example, a power converter includes a bidirectional converter electrically coupled between an alternating current (AC) power system and a direct current (DC) power system, where the bidirectional converter includes a number of phase legs. The power converter can also include a control system configured, during a portion of a line cycle of the AC power system, to clamp a first phase leg of the converter from switching and operate second and third phase legs of the converter independently in either critical conduction mode (CRM) or in discontinuous conduction mode (DCM).

Abstract: A system and methods for active voltage balance of capacitors connected to a DC power source and to a three-phase three-level inverter, implemented by a controller comprising a space vector diagram is disclosed.

Abstract: A power conversion apparatus includes arms in each of which one or more unit converters each including a capacitor and capable of outputting an arbitrary voltage are connected in series, and a point P as a first node to which one end of the respective arms are Y-connected, and a point N as a second node to which a neutral terminal of the rotary electric machine is connected. The other end of the respective arms are connected to one ends of respective phase windings of a rotary electric machine.

Abstract: A ballast circuit that facilitates providing thermal protection for a fluorescent lamp includes a coupling transformer that couples an inverter circuit to a control circuit. First and second transformer windings in the inverter circuit, and a third transformer winding in the control circuit, are wound around a common ferrite core. The ferrite core has a Curie temperature that approximates a maximum allowable threshold temperature for the lamp. When the temperature of the ballast approaches the Curie temperature of the ferrite core, its permeability, and thus inductance, drops dramatically, causing an increase in operating frequency in the inverter circuit. This increased operating frequency causes a capacitor in the control circuit to charge to a threshold voltage, at which power to the inverter circuit is reduced. The lamp then dims without turning off until the temperature is reduced to an acceptable level.

Abstract: Three-level inverter and rectifier power conversion systems and space vector modulation (SVM) controls having even-order harmonic elimination for neutral voltage balancing with a predefined vector switching sequences for half-wave symmetry in open loop system operation. The vector sequence listings for each SVM diagram segment includes switching state entries individually indicating one of three possible switching state levels positive (P), zero (0), or negative (N) for each of three or more switching groups of the power conversion system, with listings for each pair of first and second diametrically opposite diagram segments include symmetrically opposite switching states, with positive levels in the entries of the listing for the first segment corresponding to negative levels in the entries of the listing for the second segment and vice versa.

Abstract: A magnetic frequency triplo-multiplier for use as a power source for metal melting furnaces and the like. The frequency triplo-multiplier has Y-connected primary windings that are resonant with each phase of a three-phase alternating-current power source and serially-connected secondary windings that are resonant with a triple frequency so as to produce a large single-phase power. The frequency triplo-multiplier uses a five-legged iron core, and capacitors connected in parallel with first, third and fifth leg windings of the five-legged iron core to bring about resonance with the three-phase alternating-current power source, while second and fourth leg windings of the five-legged iron core are connected in series and shunted by a capacitor so as to bring about resonance with a triple frequency.

Abstract: A sun tanning apparatus has an electronic operating system comprising: (i) a plurality of pairs of fluorescent lamps for providing tanning radiation, each pair of lamps being adapted to be powered from 30 kHz/120 Volt by way of a high-Q series-resonant L-C ballasting circuit; (ii) a relatively low-power frequency converter connected with the power line and operable to provide power for heating the cathodes in these fluorescent lamps, thereby conditioning the lamps for easy starting; (iii) a relatively high-power frequency converter also connected with a power line and operable to provide the 30 kHz/120 Volt required for operating the plurality of pairs of fluorescent lamps by way of the high-Q series-resonant L-C ballasting circuit; and (iv) delay means operable to prevent the 30 kHz/120 Volt provided by the high-power frequency converter from being applied to the fluorescent lamps until after power has been applied to heat the lamp cathodes for at least one second.

Abstract: A static electromagnetic frequency changer utilizes linear inductances and capacitances and a saturable reactance to generate subharmonic frequencies. The magnetic components of the circuit are designed to be combined on a single magnetic structure. The frequency changer is rendered relatively insensitive to slight changes in the frequency and amplitude of the driving signal through the inclusion of a feedback winding.