213 results about "Magnetizing inductance" patented technology

A primary side sensing power control system and method for constant current control that utilizes a relationship that involves the measured reset-time from the previous cycle to determine the primary side peak current and off-time for the next cycle. This control mechanism does not need the knowledge of input voltage or magnetizing inductance. Therefore, it removes the sensitivities of input voltage and magnetizing inductance to the output current limit. Furthermore, it uses a time measurement instead of a voltage measurement for the current calculation which in many cases is easier to perform.

The present invention proposes an improved circuit design and configuration of a DC-DC converter with resonant reset. In this present invention, the active resonant snubber in parallel to a primary winding of a transformer of a DC-DC converter for resetting the transformer includes a resonant capacitor, an active switch connected to the resonant capacitor in series, an auxiliary diode coupled across the active switch in parallel, and an auxiliary winding coupled with the transformer. When a main switch of the DC-DC converter is turned off, the auxiliary winding turns on the active switch, and then the transformer is reset by a resonance between a magnetizing inductor of the transformer and the resonant capacitor.

Systems and methods for implementing line overload control via providing distributed series impedance are disclosed. One system, amongst others, comprises at least one distributed series reactor (DSR). Each DSR comprises a single turn transformer (SST) comprising two split-core sections (132), a winding (120), and an air-gap (138), the air-gap designed such that a magnetizing inductance is produced when the two split-core sections (132) are clamped around a conductor (108). Each DSR further comprises a contact switch (122) that short circuits the winding when the contact switch (122) is in a closed condition, a power supply (128) that derives power from conductor line current, and a controller (130) configured to open the contact switch when the conductor line current reaches a predetermined value, thus causing insertion of the magnetizing inductance into the conductor. The controller (130) may be further configured to close the contact switch (122) when the conductor line current drops below the predetermined value.

An LLC resonant converter optimization design method comprises the steps of: A, acquiring the performance parameters of an LLC resonant converter; B, converting an LLC resonant converter circuit into an equivalent circuit; C, according to the condition that the power factor angle of the resonant circuit power factor is zero, determining the first relation between the specific value m of the magnetizing inductance and the resonant inductance of the LLD resonant converter and the quality factor Q; D, according to the relation between the voltage gain and the normalization operating frequency extremal point, determining the second relation between the specific value m of the magnetizing inductance and the resonant inductance of the LLD resonant converter and the quality factor Q; E, combining the first relation with the second relation, calculating the specific value m of the magnetizing inductance and the resonant inductance of the LLC resonant converter and the quality factor Q; and F, on the basis of the specific value m of the magnetizing inductance and the resonant inductance and the quality factor Q, determining the resonant inductance, the magnetizing inductance and the resonant capacitance value of the LLC resonant converter. The LLC resonant converter optimization design method can implement the design policy that both the conversion efficiency and the safety of the LLC resonant converter are given consideration.

The invention discloses an asymmetric half-bridge converter and a control method thereof. A one-way clamping network is additionally arranged and is connected in parallel with a primary side, a secondary side or a third winding of a transformer, an auxiliary switch is controlled to be switched off when an excitation inductance current reaches a set value, the one-way clamping network is conducted,a clamping current passes through the one-way clamping network, the clamping current is clamped and maintained to be basically unchanged by the one-way clamping network, the one-way clamping networkis controlled to be switched off within a certain time before a main switch is conducted, the clamping current is released, voltages of two ends of the main switch are reduced to zero or be approximate to zero, and zero-voltage conduction of the main switch is achieved. By the asymmetric half-bridge converter, effective control of negative peak of the excitation inductance current can be achieved,a current effective value of a power device under light load of a converter is reduced, the light-load efficiency of the converter is substantially reduced under the condition that the advantages ofzero-voltage conduction of an existing technical scheme is maintained, the no-load loss is reduced, and control implementation is simple and efficient.

A method is shown to improve any forward topology operation to achieve efficient resonant transitions by actively shorting the magnetizing inductance and release the short at another time thus producing lower switching losses independent of frequency. In another embodiment of this invention the current from the output inductor is allowed to go negative before the freewheeling synchronous rectifier is turned off, pushing the current back into the primary to create a soft transition across the switching elements before they are turned on. In another embodiment of the invention a current source is used to inject a negative current through the freewheeling synchronous rectifier before is turned off with the purpose of transferring the current into the primary to discharge the parasitic capacitances of the primary switchers before are turned on. An optimized control method can be utilized to tailor the frequency to create the necessary conditions requested by the embodiments of the invention.

The invention discloses a full-bridge zero-voltage boost switching resonant converter based on LLC used for UPS. The converter is characterized in that resonant converting circuit in DC/DC convertingmodule is full-bridge LLC resonant converting circuit and the converting circuit comprises switch bridge which is composed of four main switching tubes through full-bridge connection, main transformerof which primary winding is in parallel with excited inductor, series resonance inductors connected with the main transformer, series resonance capacitors, and LLC resonance network composed of excited inductor, series resonance inductors and series resonance capacitors, wherein the network is connected with the two output ends of the switch full-bridge, and output sides of the main transformer is synchronous full wave rectifying circuit composed of two groups of rectifying diodes and are separately connected with two output capacitors sharing the same ground wire. The full-bridge zero-voltage boost switching resonant converter of the invention overcomes the defect that switch tube zero-voltage conduction in full scope is hard to realize, the work is easy to reach optimal state, the testvalue of the practical boosting circuit efficiency is about 95%, the volume of electromagnetic elements is reduced, the circuit is simplified and the cost is reduced.

Improved performance of a noise separator circuit capable of separating common mode (CM) and differential mode (DM) components of electromagnetic interference (EMI) noise are provided by arrangement of terminating impedances such that the circuit is fully symmetric with respect of a pair of input ports. The noise separator circuit is further improved by perfecting features for canceling effects of parasitic inductances and capacitances, parasitic capacitance and inductance between circuit connections such as printed circuit board traces, minimizing leakage inductance effects of pairs of coupled inductors and mutual inductance effects between pairs of coupled inductors, providing sufficient magnetizing inductance for low frequency response, and preventing saturation of inductors using switched attenuators, providing a plurality of ground planes, choices of terminating resistors and circuit layout.

A pulse width modulation resonance converter is provided that includes a transformer and a switching unit including first to fourth switches electrically connected to a primary coil of the transformer and configured to convert a DC voltage into an AC voltage by a switching operation of the first to fourth switches in which each switch is switched from an off state to an on state when a voltage difference between both ends is about 0. Additionally, a rectifying unit includes an output capacitor, first to fourth diodes electrically connected to a secondary coil of the transformer, and a resonance tank having a resonance capacitor and a resonance inductor which are electrically connected to the secondary coil of the transformer. The plurality of switches connected to the primary side of the transformer perform the zero-voltage switching using the magnetized inductance of the primary side to minimize the switching loss.

The invention provides an interleaved parallel magnetic-integration bidirectional full-bridge LLC resonant converter and relates to the technical field of power and electronic applications. The interleaved magnetic-integration bidirectional full-bridge LLC resonant converter comprises two paths of an interleaved parallel bidirectional full-bridge LLC resonant converter. The first path of the bidirectional full-bridge LLC resonant converter comprises a first primary-side circuit, a first secondary-side circuit, a resonant transformer and a magnetic inductor thereof. The second path of the bidirectional full-bridge LLC resonant converter comprises a second primary-side circuit, a second secondary-side circuit, a resonant transformer and a magnetic inductor thereof. The primary-side circuit and the secondary-side circuit of each path of the bidirectional full-bridge LLC resonant converter are respectively in the form of a full-bridge LLC resonant circuit and are used for realizing the bidirectional energy flow. The two resonant transformers, the magnetic inductors thereof and four resonant inductors of the two paths of the interleaved parallel bidirectional full-bridge LLC resonant converter are magnetically integrated through integrated magnetic pieces. According to the technical scheme of the invention, the large-power, high-transformation-ratio, small-volume, bidirectional and high-efficiency operation of the electric energy is realized.

A system for identifying magnetizing inductance and rotor resistance of an induction machine comprises an induction machine comprising a rotor and a stator, a DC voltage bus, and a DC-to-AC voltage inverter coupled to the DC voltage bus and to the induction machine. The system also comprises a controller configured to cause the DC-to-AC voltage inverter to apply a square-wave excitation to a plurality of phases of the induction machine, determine a stator resistance of the stator of the induction machine based on the square-wave excitation, and determine a rotor resistance of the rotor of the induction machine based on the square-wave excitation. The controller is also configured to calculate a magnetizing curve for the induction machine based on the stator and rotor resistances and control the induction machine to operate based on the magnetizing curve.

The invention discloses an on-line parameter identification simulation method for excitation inductance of a linear traction motor. The on-line parameter identification simulation method comprises thesteps of building a state space equation taking a primary current and secondary magnetic flux as a state variable, a primary voltage as an input variable and a primary current as an output variable of the linear traction motor under static coordinate according to a mathematical model of the linear traction motor; obtaining an all-order state observer model of the linear traction motor after statereconfiguration and state variable error feedback correction; and building an on-line parameter identification model reference adaptive system of the linear motor to obtain an on-line identificationalgorithm of the excitation inductance by taking the state space model of the linear traction motor as a reference model and the all-order state observer model of the linear traction motor as an adjustable model. The on-line parameter identification simulation method can be applied to different working conditions of running of the linear traction motor, the influence of a dynamic side edge effecton the linear traction motor is fully considered, and the accurate modeling on the linear traction motor is achieved.

The invention relates to a large power high efficiency thermal equilibrium LLC resonant converter and a control method thereof. The large power high efficiency thermal equilibrium LLC resonant converter comprises an inversion circuit, a resonant network, high frequency transformers, and an output rectification circuit. The high frequency transformer is constituted by 2n transformers, and the primary windings of the 2n transformers are serially connected together, and the secondary windings of the 2n transformers are parallely connected together, and then are connected with the output rectification circuit. The primary windings are parallely connected with excitation inductors, and the resonant network is constituted by resonant capacitors, the primary excitation inductor of the2n-1th transformer, and the primary excitation inductor of the 2nth high frequency transformer, which are serially connected together. The resonant converter works in six working modes in a switching period. The high frequency transformers are used to replace the resonant inductors, and then the high frequency transformers are used as the resonant inductors, and are also used as the excitation inductors and the transformers, and therefore material costs are saved, output ripple, output precision, and other performances are greatly improved.

An AC/DC power converter utilizing a single stage boost-asymmetric LLC topology is disclosed. The converter uses a combined pulse width modulation (PWM) and frequency modulation (FM) to achieve dual control for a single main magnetic element (transformer). The transformer provides an output voltage regulation throughout the primary-secondary isolation operating in resonant mode (LLC) by means of frequency modulation, while at the same time its magnetizing inductance is conditioning the input current and providing a boosted high voltage for energy storage purpose by means of duty cycle control. A single pair of complementary primary switches is used to drive the primary winding of the transformer in order to achieve both voltage regulation and power conditioning. The secondary side capacitors and the resonant inductor, which may be either integrated into the transformer or external to the transformer, achieve the resonant function of the transformer.

The invention discloses an optima design method of an LLC resonant converter. The method comprises the following steps: determining transformer ratio of transformation according to a design index of an LLC resonant converter; determining the primary side turns, the secondary side turns, a winding structure and a magnetic core shape of the transformer according to the ratio of transformation of thetransformer, and initially designing a transformer; measuring a parasitic capacitance of the transformer; deducing the relation formula of switch-on loss and dead time to obtain the optimal dead timewhen the switch-on loss is minimum; determining the optimal magnetic inductance according to the optimal dead time; selecting the inductance ratio and quality factor capable of satisfying a gain condition; and obtaining a resonance inductance value and a resonance capacitance value according to the optimal magnetic inductance, the inductance ratio and the resonance frequency; and changing the airgap of the transformer to enable the magnetic inductance to be equal to the optimal magnetic inductance. Through the method disclosed by the invention, the problem that the traditional LLC resonant converter design method depends too much on the experience and is inaccurate is solved, the design result is more accurate, and can be popularized to various application occasions.

The invention provides a parameter design method of a full-bridge LLC resonant converter. According to the method, the values of a primary and secondary turn ratio, magnetizing inductance, resonant inductance and resonant capacitance of the transformer are determined according to preset target parameters, and when the four parameters are determined, the magnitudes of a dead time, the switching current of a switch tube and the equivalent junction capacitance of the actual switch, the turn-off current of the switch tube and the equivalent junction capacitance of an actually selected switch tubeare fully considered. While a converter gain is satisfied, the ZVS of a primary switch tube during the actual operation of the converter, primary and secondary RMS current and the switch tube turn-offcurrent are reduced at the same time, and the loss of a switching device is reduced. In addition, the operating frequency of the converter can be strictly defined in a preset range, and the design ofan input side filter and the design of the transformer are facilitated.

The present invention discloses an interleaving LCLC resonant converter with a wide load and a wide gain. The interleaving LCLC resonant converter comprises an input direct current source, two primaryinversion networks, two first resonance inductors, two first resonance capacitors, two second resonance inductors, two second resonance capacitors, two transformers, a secondary rectification circuit, an output filter capacitor and an output load. A hybrid control mode of frequency conversion and phase shift is employed to achieve wide voltage gain in a wide load condition. The second resonance capacitors and the second resonance inductors are connected in series to obtain adjustable equivalent excitation inductance, the equivalent excitation inductance is smaller to facilitate achieving of the high voltage gain at a low frequency, and the equivalent excitation inductance is larger to facilitate improvement of the working efficiency at a high frequency. The maximum switching frequency isa resonant frequency, the phase between the two modules is regulated at this frequency to further widen the voltage gain so as to ensure the zero-voltage turning-on of a primary switch tube and the zero-current turning-off of a secondary rectification tube in the whole working range and facilitate achievement of high efficiency and high power density.

A DC-to-AC inverter provides power to a DC-to-AC converter via an isolation transformer. The DC-to-AC converter drives a DC load. A sensing circuit on the primary side of the isolation transformer senses the current flowing through the primary winding of the transformer. A capacitor is connected across the primary winding in parallel with the magnetizing inductance of the primary winding to form a parallel L-C combination. The capacitance of the capacitor is selected with respect to the magnetizing inductance such that the parallel L-C combination resonates at a nominal steady-state operating frequency of the DC-to-AC inverter, which causes the current through the primary winding to be proportional to a current through the DC load. The current through the primary winding is sensed and provided as a feedback signal to the DC-to-AC inverter to cause the DC-to-AC inverter to adjust the operating frequency to maintain the current at a desired magnitude.

The invention discloses a switching power supply device. The switching power supply device comprises an asymmetric half-bridge flyback converter and a controller; and the asymmetric half-bridge flyback converter is used for converting an input voltage into an output voltage, and comprises a main switch, an auxiliary switch, a transformer and a one-way clamping network used for controlling a negative peak value of an excitation inductive current. A controller is used for controlling the main switch, the auxiliary switch and the one-way clamping network, so that the switching power supply deviceworks in a certain working state. The switching power supply device is characterized in that when the output load current is greater than or equal to a first load current set value, the controller enables the switching power supply device to work in an asymmetric half-bridge flyback mode; and when the output load current is smaller than the first load current set value, the controller enables theswitching power supply device to work in a clamping asymmetric half-bridge flyback mode. Under the condition that the advantages of full load and heavy load high efficiency of the switching power supply device are kept, the current effective value of the power device under light load and no load can be reduced, the light load efficiency is greatly improved, and the no-load loss is reduced.

The invention discloses a primary inductance correction circuit applied to a flyback switching power supply. The primary inductance correction circuit mainly solves the problem that the primary magnetic inductance of a conventional transformer is deviated to influence output power. The primary inductance correction circuit comprises a clamper, a sampling control and current-voltage converter, a voltage stabilizer/isolator, a voltage-current converter, an equilibrium point controller and an oscillator. In the power tube conduction time of the flyback switching power supply, the sampling and current-voltage converter samples current flowing out of a control end, performs I-V conversion, voltage stabilization/isolation and V-I conversion on discontinuously sampled current, and outputs offset current. The clamper clamps the voltage at the control end to zero. The equilibrium point controller makes the offset current be zero when a primary magnetic inductance value is normal. The offset current is injected into the oscillator to change the frequency of the oscillator and further change switching frequency to correct an output power change caused by inductance tolerance. The primary inductance correction circuit has a simple structure, low power consumption and stable and accurate offset current.

The invention discloses a high-efficiency tightly-coupled LLC resonance transformer. The high-efficiency tightly-coupled LLC resonance transformer comprises an annular main transformer which is provided with a magnetic core having no air gaps; one end of a primary coil of the main transformer is connected with an input auxiliary inductor; the two ends of a second secondary coil of the main transformer are respectively connected with the two ends of an output auxiliary inductor; the primary coil is uniformly intertwined on the innermost layer of the magnetic core of the main transformed after being coated with an insulating layer which is bound by a plurality of varnished wires or flat copper; a first secondary coil of the main transformer is uniformly intertwined a second layer of the magnetic core of the main transformed after being coated with an insulating layer which is bound by a plurality of varnished wires or flat copper; the second secondary coil is uniformly intertwined on the outermost layer of the magnetic core of the main transformed after being coated with an insulating layer which is bound by a plurality of varnished wires or flat copper. The high-efficiency tightly-coupled LLC resonance transformer disclosed by the invention guarantees tight coupling of the transformer, nearly prevents magnetic leakage, can also satisfy the requirements on parameters of a magnetic inductor, and is greatly improved in energy transmission efficiency in comparison with a traditional LLC transformer.

The invention discloses a low-output ripple power factor correction converter which specifically comprises a rectifier bridge, a filter, a Buck PFC converter, a post-stage DC-DC converter and a control circuit thereof. The filter is composed of Lf and Cf; a transformer is allowed to be equivalent to an excitation inductor, an ideal transformer and a leakage inductor; the Buck PFC converter and thepost-stage DC-DC converter are integrated together by sharing an active switch; the Buck PFC converter is composed of a diode, an inductor, a capacitor and an active switch. The DC-DC converter is composed of a diode, a resonant capacitor, an output capacitor, a transformer, an active switch and an energy storage capacitor. The converter has the advantages of high efficiency, high power factor, low output ripple and the like, and is easy to expand into multi-path output. In addition, the converter is of an isolation structure and is safer.

The invention relates to a turn ratio adjustable type matrix transformer integrated with synchronous rectifier tubes. The matrix transformer is applicable to a half-bridge LLC resonant converter undera MHz switch frequency. The matrix transformer comprises four separated transformers, each transformer is provided with a primary winding and a center-tapped secondary winding symmetrically coupled with the primary winding, the primary windings of the four separated transformers are connected in series and the center-tapped secondary windings symmetrically coupled with the primary windings are connected in parallel, a primary winding control switch tube is connected to each primary winding in parallel, and one resonant inductor and one magnetic inductor in the LLC resonant converter are respectively integrated to each primary winding; and two synchronous rectifier tubes and two output capacitors are respectively integrated to each secondary winding, the working modes of the synchronous rectifier tubes are influenced by the primary winding control switch tubes, the effective numbers of turns of the primary windings are changed through switching on or off the primary winding control switch tubes, and then the turn ratio of the primary windings to the secondary windings is adjusted.