38results about How to "Reduce circulating current" patented technology

Disclosed is a hybrid dc-dc converter. The hybrid dc-dc converter includes: a pair of transformers configured to magnetically couple a primary side to a secondary side, a full-bridge converter including four switches constituting a full-bridge inverter circuit and a first transformer, and an LLC resonant converter including a resonant inductor, a resonant capacitor, and a second transformer, which constitute an LLC resonant circuit, wherein an output of the full-bridge converter and an output of the LLC resonant converter are connected to each other in series at the secondary side.

Embodiments of the present invention provide novel techniques for using multiple 18-pulse rectifier circuits in parallel. In particular, each rectifier circuit may include an autotransformer having 15 inductors coupled in series, joined by 15 nodes interposed between pairs of the inductors. The inductors may be represented as a hexagon in which alternating sides of the hexagon have two and three inductors, respectively. Each rectifier circuit may also include three inputs for three-phase AC power coupled to alternating vertices of the hexagonal representation and nine outputs for AC power coupled between each node that is not a vertex of the hexagonal representation and a respective diode bridge. Outputs of the diode bridges for the rectifier circuits may be coupled to a DC bus. In addition, a means for reducing circulating current between the parallel rectifier circuits and for promoting load sharing between the parallel rectifier circuits is also provided.

The present disclosure relates to an LC snubber circuit for a switching converter, wherein the switching converter includes an inductor and a switching device connected in series. The LC snubber circuit can include a first snubber diode, a snubber capacitor, a second snubber diode, and a snubber transformer having a primary winding and a secondary winding. The secondary winding of the snubber transformer is connected to an output of the switching converter.

The invention provides a resonant converter based on ON/OFF control. The resonant converter comprises a primary side square wave inversion circuit I, a primary side LLC resonance circuit II, a transformer T, a secondary side full-bridge rectification circuit III and an output resistance load Ro. The resonant converter is characterized in that two auxiliary two-way switches are added to the primaryside square wave inverter circuit I; ON/OFF control is adopted for the auxiliary two-way switches, so that the resonant converter can work in a full-bridge LLC resonant converter mode and can also work in a half-bridge LLC resonant converter mode. Due to the topological structure of the resonant converter and the switching type control mode of the resonant converter, the switching frequency change range of the resonant converter is narrow, ultra-wide-range voltage gain adjustment is achieved, zero-voltage switching of a primary side switching tube is achieved, zero-current switching of a secondary side rectifying diode is achieved, and switching loss is reduced.

Embodiments of the present invention provide novel techniques for using multiple 18-pulse rectifier circuits in parallel. In particular, each rectifier circuit may include an autotransformer having 15 inductors coupled in series, joined by 15 nodes interposed between pairs of the inductors. The inductors may be represented as a hexagon in which alternating sides of the hexagon have two and three inductors, respectively. Each rectifier circuit may also include three inputs for three-phase AC power coupled to alternating vertices of the hexagonal representation and nine outputs for AC power coupled between each node that is not a vertex of the hexagonal representation and a respective diode bridge. Outputs of the diode bridges for the rectifier circuits may be coupled to a DC bus. In addition, a means for reducing circulating current between the parallel rectifier circuits and for promoting load sharing between the parallel rectifier circuits is also provided.

A method for calculating insertion indices for a phase leg of a DC to AC modular multilevel converter. Each phase leg includes two serially connected arms, wherein each arm includes a number of submodules, wherein each submodule can be in a bypass state or a voltage insert mode. The insertion index includes data representing the portion of available submodules that should be in the voltage insert mode. The method includes the steps of: calculating a desired arm voltage for an upper arm connected to the upper DC source common bar and a lower arm connected to the lower DC source common bar, obtaining values representing actual total arm voltages in the upper arm and lower arm, respectively, and calculating modulation indices for the upper and lower arm, respectively, using the respective desired arm voltage and the respective value representing the total actual arm voltage. A corresponding apparatus is also presented.

The invention provides a fixed-frequency control method of a full-bridge LLC resonant converter. The full-bridge LLC resonant converter is composed of a direct-current input source Vin, a primary sidesquare-wave generator I, a primary side LLC resonant circuit II, a transformer III, a secondary side full-bridge rectifying circuit IV, an output filter capacitor Co and an output resistance load Ro.The primary side square wave generator I is composed of a primary side first switch tube S1, a primary side second switch tube S2, a primary side third switch tube S3 and a primary side fourth switchtube S4. The primary side LLC resonance circuit II is composed of a resonance capacitor Cr, a resonance inductor Lr and an excitation inductor Lm. The primary side second switch tube S2 and the primary side fourth switch tube S4 are controlled through a pair of fixed-frequency complementary pulses, a duty ratio is 50%, and a switch frequency is equal to a series resonant frequency of the resonantcapacitor Cr and the resonant inductor Lr. Switch pulses of the primary side first switch tube S1 and the primary side third switch tube S3 are controlled through output voltage feedback, and duty ratios of the switch pulses of the primary side first switch tube S1 and the primary side third switch tube S3 are complementary.

The invention relates to a transformer continuous coil spiral transposition structure, a transposition method thereof and a manufacturing method thereof. The transformer continuous coil spiral transposition structure comprises a plurality of layers of wire cake groups which are axially arranged along a coil, wherein each layer of the wire cake group is formed by winding a plurality of wires whichare overlapped in the width direction; a special transposition structure is adopted between two adjacent layers of the wire cake groups at one half of the axial direction of the coil, or the special transposition structure is adopted between two adjacent layers of the wire cake groups at one quarter and three quarters of the axial direction of the coil, and a standard transposition structure is adopted between the other two adjacent layers of the wire cake groups; in the special transposition structure, the wires are divided into two groups, and the upper group of wires and the lower group ofwires are subjected to integral position exchange during transposition. According to the transformer continuous coil spiral transposition structure, the basic consistency of the resistance of each wire is ensured, the potential differences between the wires are greatly reduced, the circulating current is greatly reduced, the circulation loss is greatly reduced, the load loss during the operation of the transformer is further reduced, the temperature rise of the coil is reduced, and the service life of the insulating material is prolonged.

This document discusses, among other things, a stator with transposition between the windings or coils. The coils are free from transposition to increase the fill factor of the stator slots. The transposition at the end connections between an inner coil and an outer coil provide transposition to reduce circulating current loss. The increased fill factor reduces further current losses. Such a stator is used in a dual rotor, permanent magnet machine, for example, in a compressor pump, wind turbine gearbox, wind turbine rotor.

The invention provides a parallel connection power conditioning system which is provided with a filer for filtering cyclic currents, comprising an input terminal, a plurality of power conditioning devices and a load. The input terminal is used for receiving an input terminal power supply. Every power conditioning device comprises a DC-DC converter, a DC-AC transducer and the filter for filtering the cyclic currents. The DC-DC converter is used for receiving and transforming the input terminal power supply to form a steady DC voltage. The DC-AC transducer converts the steady DC voltage to an AC voltage. The filter is coupled to the DC-AC transducer for filtering noise in the AC voltage and the cyclic currents between the power conditioning devices and generating a filtration voltage. The load is connected to a plurality of power conditioning devices, wherein, a plurality of power conditioning devices are connected to the load in parallel.

The invention provides a control method based on an adaptive hybrid rectification multi-switch resonance LLC converter. The circuit is characterized in that the structure is simple, the number of required components is small under the condition that the same wide output voltage range is achieved, and the circuit comprises a capacitor unit, an inversion network, a resonance network, a high-frequency transformer, a rectification network and a pulse signal generation unit. According to the control method, fixed-frequency asymmetric pulse width (APWM) modulation is adopted, the switching frequency is fixed and equal to the resonant frequency, the conduction duty ratio of a switching tube is changed only through a pulse signal generation unit, smooth switching of a full-bridge inverter circuit, a half-bridge inverter circuit, a full-bridge inverter circuit and a voltage doubling rectifier circuit is achieved, and then ultra-wide output voltage regulation is achieved. And meanwhile, circulating current in the circuit is small, control is simple, and the size miniaturization of the transformer is facilitated.

The present invention provides a power conversion circuit system in which a circulating current can be reduced by accurately detecting the circulating current, to thereby improve efficiency in power conversion. The power conversion circuit system includes a power conversion circuit composed of a primary conversion circuit having left and right arms and a secondary conversion circuit having left and right arms, and a control circuit for controlling switching of switching transistors in the primary and secondary conversion circuits. The control circuit detects the circulating current at at least one of timings lagged by pi/2+phi/2 from at least either a peak timing or a valley timing in a carrier counter where phi represents a difference in phase between the primary and secondary conversion circuits, and performs feedback control for reducing the detected circulating current to zero.

The invention provides a brush direct-current motor which possesses a plurality brushes and can restrain the increase of a motor size so as to reduce ineffective circulating current for motor performance and to minimize calorific value. The brush direct-current motor possesses a first brush, a second brush homopolar with the first brush, and a choking coil in connection with the first brush and the second brush; one end of the choking coil is respectively in connection with the first brush and the second brush in a series connection mode; the choking coil is configured in such as way that the longer direction of the choking coil is in the diameter direction of the motor.

The invention discloses a single 24-pulse dry traction rectifier transformer with double-bridge windings arranged in a mirroring manner. The double-bridge winding adopts an axial double-split double-bridge four-winding structure, and each phase winding is nested on three conjugate iron cores which are sequentially arranged at intervals; the windings comprise three sets of primary side upper bridgewindings, three sets of primary side lower bridge windings, three sets of secondary side upper bridge triangular windings, three sets of secondary side lower bridge star-shaped windings, three sets of secondary side upper bridge extension windings, three sets of secondary side lower bridge extension windings, three sets of secondary side upper bridge common side windings and three sets of secondary side lower bridge common side windings. The size of the transformer is remarkably reduced, the manufacturing cost of the transformer is reduced, the transformer manufacturing process is simplified,and the electric energy quality of a rectifier system is improved. The short circuit impedance of the primary side single-phase winding to each set of secondary side single-phase winding can be completely consistent, and the short circuit impedance of the primary side three-phase winding to each set of secondary side three-phase winding can be completely consistent, so that the circulating current between the secondary side windings of the transformer is effectively reduced, and the local winding overheating phenomenon of the secondary side windings is prevented.