751 results about "Autotransformer" patented technology

A power control system is disclosed for controlling the power supplied to a lighting system and limiting power during time of peak demands and the like wherein the lighting system includes a power source and a lighting load connected to the power source. The control system comprises a main transformer having a first winding and a second winding, the first winding being connected between the power source and the lighting load. An autotransformer connected to the power source having a plurality of electrical transformer taps with prescribed voltage values. A plurality of solid-state tap switches is connected to the transformer taps and to the second winding of the main transformer to apply the prescribed voltage values across the second winding. A system controller has an input for receiving a voltage change signal representing a selected load voltage to be applied to the lighting load. The controller is connected to the tap switches for selectively closing one of the tap switches to produce said prescribed voltage value across the second winding of the main transformer whereby the selected load voltage is output across the first winding of the main transformer and applied to the lighting load without interruption of the lighting. A transient control circuit is connected across an output of the tap switches for dissipating transient currents during switching of tap switches.

A method for fault detection in a power transformer/autotransformer and/or interconnected power lines, which are within the zone protected by the differential protection, and particularly suitable for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e. the fault position, is within the protected zone or outside of the protected zone, delimited with current transformer locations, the protected object is disconnected if determined that the source of the negative sequence currents is within the protected zone.

The invention provides a 12-pulse converter comprising an autotransformer having a primary winding connected in a delta configuration and two secondary windings connected in star configurations, the two secondary windings being connected to two rectifier bridges that are enabled to operate in parallel by two interphase chokes, the converter further comprising means for generating an additional magnetic leakage flux in at least one of the interphase chokes so as to incorporate a smoothing choke therein.

A system and method for reducing harmonics in a circuit is disclosed. The system comprises a main rectifier, $\left(\frac{n}{3}-1\right)$

auxiliary rectifiers connected to the main rectifier, and an autotransformer connected to both the main rectifier and the auxiliary rectifiers which provides 2n-pulse rectification where n equals the number of phases of the system. The autotransformer generates $\left(\frac{n}{3}-1\right)$

auxiliary voltage sets, each auxiliary voltage set having an auxiliary voltage amplitude, k, and an auxiliary voltage phase, α, wherein $k=\sqrt{4+2\sqrt{3}\cos \left(\theta -\frac{7\pi }{6}\right)}$

and wherein $\alpha ={\sin }^{-1}\left(\frac{\sqrt{3}\sin \theta -0.5}{k}\right)$

assuming a main voltage amplitude of one and a main voltage phase of ninety degrees, wherein $\theta =\frac{180°}{n}$

and its integral multiples for all possible real values of k. The main rectifier has a main rectifier power rating, P_mdb wherein $P_{\mathrm{mdb}}\ge \left(\frac{n+3}{2n}\right)$

times the load power, and the auxiliary rectifiers each have an auxiliary power rating, P_auxdb, wherein $P_{\mathrm{auxdb}}\le \left(\frac{3}{2n}\right)$

times the load power.

Systems and methods that allow for weight and size reduction of electronics components, such as transformer rectifier units (TRUs) or autotransformer rectifier units (ATRUs), by providing a fluid cooling system is utilized to provide high heat dissipation for a transformer assembly of TRUs or ATRUs by providing a thermal interface at the windings of the transformer assembly, which are the hottest spots in such assemblies. The cooling system may include a fluid-cooled winding heat sink element or “finger,” which may be a thermally conductive bar (e.g., aluminum, copper) having microchannels therein positioned between the core and windings of a transformer or between turns of the windings of a transformer. Fluid passes through the microchannels of the heat sink element to provide direct cooling to the heat generating windings of the transformers. The heat sink element may be produced by an additive manufacturing technology.

An apparatus for powering an aircraft by generating power from a pressure spool of a turbine engine. AC power can be extracted from the turbine engine by a generator having an integrated autotransformer unit, and converted to DC power.

A filter system for attenuating electromagnetic interference (EMI) of an autotransformer-based rectification system that utilizes the leakage inductance of the autotransformer and one or more capacitors connected on the secondary side and optionally one or more differential mode inductors and input capacitors connected on the primary side to form a differential mode EMI filter. This configuration reduces the size, weight, and cost of the differential mode EMI filter when compared with a differential filter formed by placing the inductors and capacitors on the primary side.

The invention relates to an identifying method for the line breaking and ground faults of an AT power supply contact network of an electrified railway which comprises: judging and identifying whether an element achieves the starting condition or not; calculating a real time power factor according to a bus voltage and a feeder line current; calculating the self-adapting control amount and the secondary harmonic content according to the harmonics 1. 2, 3, 5 and 7 of the feeder line current; judging whether the power factor regulated by the self-adapting control amount and the self-adapting control amount are in the motion range or not and judging whether the secondary harmonic content is smaller than a setting value or not; if yes, all the conditions can be met; then giving out alarming signal or tripping, uploading the failure data information; or quitting and initializing the identifying element. The identifying method can identify the high impedance failure formed by line breaking and grounding and ensure the identifying element for the feeder line protection device of a microcomputer to be not mistakenly moved when various electric power engines run under load, under the temporary state of exciting surges and under the working condition of heavy load; simultaneously, the identifying method solves the problem of failure to operate of the normal protections after the stepout of the AT (autotransformer).

A non-isolated resonant converter is provided. The provided non-isolated resonant converter includes a switch circuit, a resonant circuit and a rectifying-filtering circuit. The switch circuit, the resonant circuit and the rectifying-filtering circuit are sequentially connected. The resonant circuit includes an auto-transformer, a capacitor and an inductor, wherein the capacitor and the inductor are connected to the auto-transformer. The configuration of the provided non-isolated resonant converter has small size, low loss and high power density.

The invention discloses a single-phase three-winding autotransformer model taking nonlinear influences of excitation impedance into consideration, which belongs to the technical field of transformers. The single-phase three-winding auto-transformer model comprises a basic electric circuit and magnetic circuit equation of a single-phase three-winding step-down autotransformer, an equivalent circuit of a single-phase three-winding autotransformer, an equivalent circuit of a single-phase three-winding step-up autotransformer, an expression of an excitation impedance zm and an expression of the single-phase three-winding autotransformer model taking account of the nonlinear influences of the excitation impedance. The autotransformer model not only takes account of the magnetic coupling between a high-voltage winding and a medium-voltage winding but also takes account of the electrical relationship, and the result of a harmonic characteristic simulation performed by the single-phase three-winding autotransformer model is more actual than that of the harmonic characteristic simulation performed by a common three-winding transformer instead of the three-winding autotransformer. The excitation impedance not only comprises generally non-ignorable nonlinear inductance reflecting iron core saturation characteristics, but also takes account of the nonlinear resistance reflecting iron losses, and the harmonic characteristic of a transformer can be analyzed more accurately by using the excitation impedance.

A voltage compensation circuit is disclosed for proving an elevated output AC voltage upon an under voltage input AC voltage condition. The voltage compensation circuit comprises an autotransformer having a first and a second autotransformer winding. A first position of a switch connects the first autotransformer winding to the input AC voltage for providing an elevated output AC voltage at the second autotransformer winding. The second position of the switch shorting the first autotransformer winding for providing a non-elevated output AC voltage.

A superposition principle of waveform based on conceptions of waveform continuity and flexible regulation of voltage proposes three concepts, respectively being flexible AC transformation, flexible power transmission and transformation and flexible voltage regulation; proposes three new technologies, respectively being a transient impedance technology, a flexible stepless voltage regulation technology and a flexible stepped voltage regulation technology; proposes three new products, being an AC voltage regulating electronic switch, a transient impedance transformer and a high-speed voltage regulating transformer; proposes six high-voltage power grid connection methods, being a power grid connection method type of a transient impedance transformer, a power grid connection method of a transient impedance step up auto transformer and the like; and proposes a new reactive compensation connection method for a reactive compensation device.

The invention discloses an autotransformer with low-voltage compensation, comprising a main transformer, a voltage regulator and a compensating device, wherein the main transformer comprises a low voltage winding, a common winding and a series winding; the voltage regulator comprises a voltage regulating switch, a voltage regulating winding and a first exciting winding which carries out excitationfor the voltage regulating winding; the compensating device comprises a compensation winding and a second excitation winding which carries out excitation for the compensation winding; the beginning end of the low voltage winding is connected with the beginning end of the first exciting winding; and the tail end of the low voltage winding is connected with the compensation winding in series. The autotransformer is characterized in that the tail end of the first exciting winding is connected with the tail end of the compensation winding. By adopting the voltage regulating compensation connection method of the invention, the low-voltage compensation is complete compensation for the autotransformer of variable flux voltage regulation of a neutral point, so that low voltage fluctuation can bethoroughly solved when a transformer regulates the voltage.

A filter uses a special autotransformer that has a ferromagnetic core with a plurality of legs and flux return bars. A first coil is located on one leg, and a second coil is located on the same leg, but spaced from the first coil. The first coil and at least part of the second coil are connected in series to receive distorted alternating current and at least that part of the second coil is connected to an output terminal. Between the coils and extending at least part of the way from the first leg to an adjacent leg is a magnetic shunt assembly to divert part of the flux generated in the first coil by the alternating current so that that part does not link with the second coil. An air gap is located to link with the second coil to create an inductor in that coil by flux in the second coil, and a capacitor is connected across the second coil to tune it to the fundamental frequency of the alternating current and substantially reduce harmonics in that current.

A power factor correction converter and a power factor correction conversion device, includes two groups of bidirectional switches, an autotransformer, a boost inductor, a bus filter capacitor, two front bridge arms; and a rear bridge arm; the front end of each group of bidirectional switches are connected to a coil of the autotransformer in one-to-one correspondence, and a rear end of each group of bidirectional switches is connected to one end of an AC input power grid; a central tap of the autotransformer is connected to an output end of the boost inductor, and an input end of the boost inductor is connected to the other end of the AC input power grid; a front end of each group of bidirectional switches is connected to a front bridge arm, and a rear end is connected to the rear bridge arm.

An irregular polygon connection of a three-phase autotransformer using only five windings per phase provides a source of nine-phase power suitable for an 18-pulse AC to DC power converter. The windings are connected in a manner to limit the amount of third harmonic current circulating in them. When the autotransformer is used to power a nine-phase AC to DC converter its kVA rating is typically less than 50% of the DC load kW. An additional tap on one of the five windings allows a wide range of AC output voltages to be obtained. Voltages greater than, less than, or equal to the AC input voltage can be obtained. Other multi-phase outputs are feasible. Additional isolated windings can provide means for the invention to operate as an efficient double-wound transformer.

The invention relates to an adjustable high-voltage negative-ion generation device, which comprises an input circuit, a discharge circuit and a pulse width modulation circuit, wherein the input circuit is used for providing power and at least includes a current limiting resistor and a power supply; the discharge circuit is used for generating negative ions and at least includes a switching tube, a storage capacitor, an autotransformer, a rectifier diode and a receptor; and the pulse width modulation circuit is used for controlling the switching tube. When the power supply is plugged in, the device can change pulse width modulation frequency according to the changes of environmental conditions. More electric energy can be stored through a charging circuit, then boosted to a stable high voltage by utilizing a boosting and rectifying circuit, and controlled through the pulse width modulation circuit; the production quantity can be adjusted according to the changes of the environmental conditions, so as to meet actual demands and avoid energy waste.

A method for testing residual magnetism based on interchange means includes forming test circuit by connecting oscilloscope, switch, continuous self-coupling transformer, second winding current mutual inductor to be tested, two test probes and integration module; regulating said transformer to record voltage and current waveform on oscilloscope using cursor to calculate full wave average value to confirm residual magnetism; reversing power supply; repeating above said recording and calculating steps to derive out average value according to calculated out residual magnetism value.