1316 results about "Leakage inductance" patented technology

Provided is a current-source push-pull DC-DC converter using an active clamp circuit for reusing energy of leakage inductances by not only diodes on a secondary side of a transformer being zero-current switched using a series-resonant full-wave rectifier, but also the active clamp circuit on a primary side of the transformer, which provides a discharge path of the energy stored in the leakage inductances, increases power conversion efficiency even for a wide input voltage range and reduces a switch voltage stress as compared to a conventional current-source push-pull circuit by operating even for a duty ratio below 0.5 by flowing a current of an input inductor through capacitors of the active clamp circuit when both main switches are off.

Voltage regulators often have coupled output inductors because coupled output inductors provide improvements in cost and efficiency. Coupled inductors are often used in multi-phase voltage regulators. Feedback control of voltage regulators often requires accurate and responsive sensing of output current. Provided is a technique for accurately sensing the magnitude of output current in coupled inductors. An RC circuit (comprising a resistor and capacitor in series) is connected in parallel with the coupled inductor. The inductor has a leakage inductance Lk and a DC (ohmic) resistance of DCR. The resistor and capacitor are selected such that an RC time constant is equal to an L/R time constant of Lk/DCR. With the matching time constants, a sum of voltages on the capacitors is accurately proportional to a sum of currents flowing in the output inductors. Also provided is a technique for sensing current when an uncoupled center tap inductor is present.

A converter has a transformer with primary and secondary windings each having n coils in a series-series arrangement connected to primary and secondary sides. The primary side has n primary legs each having a top switch and a bottom switch and connected to the primary winding therebetween. The secondary side has n secondary legs, each secondary leg has a synchronous rectifier switch and an output filter inductor connected to the secondary winding therebetween. A complimentary control for the primary side comprising a gate driver transformer with primary winding in series with a DC blocking capacitor connected to a drain and a source of the top switch of each primary leg, and a gate drive transformer, for each primary leg, with secondary winding containing a leakage inductor and in series with a DC blocking capacitor and a damping resistor connected to gate and source of the secondary side synchronous rectifier.

A voltage boost power converter circuit, having an input inductor, active switch, and a transformer having primary, secondary and auxiliary windings. A clamping capacitor and a first passive switch are in series across the primary winding. The auxiliary winding and a second passive switch are in series, connected to the node between the clamping capacitor and first passive switch. The active switch is connected between ground the primary winding. A bulk capacitor forms a series loop including the active switch and primary winding. The method efficiently resets a the transformer, by transferring power to a load through the primary winding, and discharging a clamping capacitor through a separate inductively linked winding of the transformer during an ON state; and clamping the active switch voltage with the clamping capacitor, charging the clamping capacitor with a leakage inductance of the transformer, and charging the bulk capacitor during an OFF state.

The invention relates to a control method which can be applied to an active-clamp flyback miniature photovoltaic grid-connected inverter device. The active-clamp flyback miniature photovoltaic grid-connected inverter device comprises a flyback converter and a power frequency polarity conversion circuit. In the device, a current reference is used for controlling a flyback primary-side current peak value so that the device can output a half-wave sinusoidal current, and the output voltage is clamped by a grid voltage. When the instantaneous power is lower, a constant frequency current discontinuous mode in combined with a variable frequency current critical continuous mode is adopted in the flyback control method. When the flyback converter works in a variable frequency current critical discontinuous mode, an auxiliary switching tube can be conducted for a period of time when the secondary-side current of the flyback converter reaches zero, the conduction time can be accurately controlled by a digital chip, thus realizing the leakage inductance energy feedback and the soft switch of a master switching tube under the condition of wide-range output voltages and different instantaneous powers and greatly improving the efficiency under the condition of full loads.

A transformer module includes a main primary winding coupled to a first input power source to receive a medium voltage signal, multiple main secondary windings each to couple to a power cell of a drive system, and an auxiliary primary winding coupled to a second input power source to receive a low voltage signal. The auxiliary primary winding can be spatially separated from the main windings to increase leakage inductance. The auxiliary primary winding can be active during a pre-charge operation to pre-charge the power cells.

A hybrid constant current control system that uses both pulse width modulation (PWM) and pulse frequency modulation (PFM) control. When transitioning from constant voltage mode to constant current mode the present invention can continue to control using PWM. Thereafter, when the voltage has dropped, the present invention smoothly transitions to PFM mode. The point of transition is based upon the switching frequency and the lowest rated voltage of operation. The system and method avoids very short (narrow) Ton times which ensures accurate constant current (CC) control with bipolar junction transistor (BJT) devices. The present invention also avoids acoustic noise because the switching frequency is maintained at a high enough level to avoid such acoustic noise even when the energy transferred through the transformer is still substantial and the output voltage is not too low. In addition the output current limit is insensitive to variation in the inductance-input voltage ratio, and is minimized against leakage inductance.

The subject invention reveals improvement methods for circuits that use a coupled inductor wherein overshoot and ringing associated with leakage inductance of said coupled inductor is entirely eliminated by addition of non-dissipative active clamp networks that clamp each winding during each operating state of a power supply containing said coupled inductor. A further improvement applicable to zero voltage switching circuits that employ an inductor for driving a zero voltage turn on switching transition of a switch enables elimination of said inductor and preserves said zero voltage switching properties by adding leakage inductance to a coupled inductor without any adverse overshoot and ringing effects associated with said leakage inductance. The subject invention also reveals a coupled inductor with enhanced leakage inductance which can be used with said other improvements. Example circuits including zero voltage switching flyback and forward converters which require only one magnetic circuit element are revealed. Zero voltage switching tapped inductor buck and boost converters with a single magnetic circuit element are also revealed.

The invention relates to a method for recognizing parameters of asynchronous motor. The stator resistance of motor is measured by a method of DC volt-ampere. The rotor resistances as well as leakage inductance of stator and rotor of motor is obtained by short circuit test. Mutual inductance of stator and rotor of motor can be taken from method of no-load test. Compensating voltage drop in on state, switch time delay and dead time raises the accuracy and stability of recognized parameter. The resistance values of rotor at frequency of rating sliding difference are calculated by method of two points through test of locked rotor at two frequencies. Since skin effect is overcome, the resistance values of rotor are accurate enough so as to meet the requirement of vector control system completely.

The invention discloses a forward-flyback isolated type boost inverter realized by coupling inductors and application thereof, comprising two power switch tubes, two auxiliary switch tubes, four anti-parallel diodes, a switch tube parallel capacitor, two clamp capacitors, two switch capacitors, two output diodes and two coupling inductors respectively provided with two windings. The invention realizes zero-voltage switching on of the power switch tubes through the resonance of the leakage inductance of the two coupling inductors and the switch tube parallel capacitor, absorbs the voltage peak switched off by the switch tubes caused by the leakage inductance and realizes energy lossless transfer by utilizing a clamp circuit comprising the anti-parallel diodes of the switch tubes and the two clamp capacitors, realizes the high gain output of the inverter by utilizing the serial connection of the second windings of the two coupling inductors, further improves the gain of the inverter and lowers the output voltage stress of the diodes by utilizing the switch capacitors and realizes the output zero-current switching off of the diodes by utilizing the leakage inductance of the coupling inductors.

The invention discloses an on-line monitoring device of transformer winding state and a monitoring method thereof. The device is used for the on-line monitoring of transformer winding deformation and bad winding contact and comprises an information acquisition unit, a parameter identification unit, a parameter processing unit and a diagnosis monitoring strategy adjusting unit, wherein the information acquisition unit collects voltage and current information on the original side and the secondary side of the transformer in real time by a data channel; the parameter identification unit identifies the winding resistance and leakage inductance parameter of the winding state of a representation transformer by the real-time voltage and current information provided by the signal acquisition unit; the parameter identification unit calculates the deviation value of a parameter value obtained by analysis and identification and a parameter reference value and takes the deviation value as the characteristic quantity which is used for measuring the quality degree of the transformer winding state; the parameter processing unit and the identification unit ensure the real-time monitoring of the transformer winding state; the diagnosis monitoring strategy adjusting unit judges whether the winding has the defect of deformation or bad contact according to the deviation value of the parameter, and takes corresponding monitoring strategy adjusting scheme according to defect types and severity thereof; and the transformer directly stops operating when the defect is serious.

The invention discloses a generator system for wind power generation and a variable speed control method; the system comprises a permanent magnetic synchronous generator of which the electrical energyoutput is connected with a Vienna rectifier device, and is characterized in that a stator winding of the permanent magnetic synchronous generator comprises two sets of triphase windings with electrical degree difference of 180 degrees and unconnected neutral points thereof; the Vienna rectifier device comprises two Vienna rectifiers with identical structure, which are in parallel connection withthe DC side with a central point O connected with a DC bus capacitance midpoint; the AC side is connected with the two triphase windings of the generator respectively; a Boost inductance of the Viennarectifier is directly provided by the leakage inductance of the windings of the generator; each Vienna rectifier device is controlled by a DSP controller to maintain the balance of the DC bus voltageby the phase current and line voltage collected in the AC side and the bus voltage collected in the DC side; and the variable speed control of the generator is realized by collecting the rotating speed of a fan and the current wind speed.

The invention discloses an flyback converting circuit of source electrode drive comprising a starting circuit, an absorbing circuit, a transformer, a first switch MOS tube, a frequency generator, an output circuit, also comprising a second switch MOS tube in which the grid electrode is connected with the frequency generator, the source electrode is connected with the ground, the drain electrode is connected with the source electrode of the first switch MOS tube; a feedback circuit which is connected between the grid electrode and the source electrode of the first switch MOS tube; an assistant power circuit which is connected between the grid electrode of the first switch MOS tube and the ground. Because the first switch MOS tube uses the source electrode drive mode to realize soft starting and closing, the on-off process is transitied slowly, which can control the appearance of outburst short time sharp peak on current when opening the first switch MOS tube, thereby reducing the opening consume and improving the product efficiency, and the electric quantity in transformer leakage inductance at the moment of closing the first switch MOS tube is used, thereby improving the product frequency.

The invention relates to a forward-flyback two-way DC-DC converter, composing a forward transformer by coupling secondary and primary windings; composing a flyback transformer by coupling another secondary and primary windings, where the two secondary windings are connected in series with the two switches tubes, respectively, and then connected in parallel with a DC power supply. The two primary windings are connected in series and then connected in parallel with a DC power supply through rectifier/inverter. It uses active clamping, RCD clamping, LCD clamping, ZVT and other techniques to compose a family of two-way converter topologies. It uses the forward transformer and a coupling inductance together to transmit energy, solving the defect in using transformer leakage inductance or coupling inductance to transmission energy; avoids the peak problem in current topologies in existing techniques; has the advantages of small current ripple, implementing soft switch for each switch tube, etc.

A DC/DC converter (1) having a plurality n of two-pole inverters (2a, 2b) connected in parallel or in series, n transformers (T_a, T_b) and n two-pole rectifiers (3a, 3b) connected in parallel or in series is described. One inverter (2a, 2b) each and one rectifier (3a, 3b) each are connected to a transformer (T_a, T_b). The inverters (2a, 2b, 2a′, 2b′) are in turn connected to a control which is provided for frequency-synchronous actuation of the inverters (2a, 2b, 2a′, 2b′) with a 180°/n phase shift. According to the invention, leakage inductances (L_S1, L_S2) of the transformers (T_a, T_b, T_a′, T_b′), together with capacitors (C₁, C₂) of the inverters (2a, 2b , 2a′, 2b′) and/or capacitors (C₃, C₄) of the rectifiers (3a, 3b, 3a′, 3b′), form in each case a resonating circuit whose resonant frequency is substantially twice as great as a clock frequency of the control signal. Furthermore, an AC/DC converter (6) is described which has a DC/DC converter (1) according to the invention with an AC/DC stage (5) connected on the input side.

An inductive component and a method for producing an inductive component are disclosed. In an embodiment, the inductive component includes a first core part having wound first and second wires and a second core part arranged on the first core part. In various embodiments the inductive component has a low mode conversion, a low inductance in differential-mode operation, a high inductance for common-mode signals, a constant characteristic impedance, a low capacitive coupling of the wires, and/or a low leakage inductance.

A drive transformer and associated circuitry for providing power and appropriate delays to primary switches and synchronous rectifiers in switch-mode power converters. The circuitry takes advantage of the leakage inductances of the drive transformer windings as well as the input capacitance of the primary switches (MOSFETs) to provide the necessary delays. No separate circuitry is needed to provide such delays, thereby providing reliability. Exemplary embodiments further disclose means to disable or enable the primary winding from a condition sensed on the secondary side even with a control and feedback circuit located on the secondary side.

A semiconductor switch 12 connected in series with a smoothing capacitor 12 is constituted by connecting in parallel a diode 13D which permits to flow current regenerated from energy of electric charges stored in a high voltage capacitor 17 to a primary side of a high voltage transformer 15 for the smoothing capacitor 12 and switching means 13S which interrupts an output from the smoothing capacitor 12, and after turning off the switching means 13S, through alternative on and off control of switching means 161S˜164S the energy of electric charges stored in the high voltage capacitor 17 is regenerated to the smoothing capacitor 12 by making use of parasitic leakage inductance 15L. As a result, an X-ray high voltage device is provided which permits to drop a wave tail of a tube voltage in a high speed without complexing the structure of the high voltage part thereof.

A transformer is to be electrically connected to a circuit board. The transformer has a bobbin, a copper sheet assembly and a coil assembly. The bobbin has two side plates and a winding core on which a primary winding, a secondary winding and a magnetic core assembly are mounted. The copper sheet assembly as the primary or the secondary winding has multiple copper sheets. Each copper sheet is an inverted U-shape with two legs, and is mounted on a groove defined on the winding core. Engaging structures formed on the copper sheets and the grooves steadily hold the copper sheet assembly on the winding core to prevent the copper sheets from shifting to incorrect positions. A conducting board below the bobbin connects the copper sheets in sequence. Since the loops formed by the copper sheets and the electrical connector are more nearly concentric, leakage inductance of the transformer will reduce.

The invention provides a method for identifying asynchronous motor parameters offline under a stationary state. The method comprises the steps of firstly, identifying a stator resistance value of a motor by using a direct current voltammetry; and then taking a single-phase rated-frequency alternating voltage and a single-phase low-frequency alternating voltage as an excitation source respectively to perform a single-phase alternating current test, obtaining steady-state response currents of the motor through detection, and obtaining a motor stator leakage inductance, a rotor inductance, a rotor resistance and a stator-rotor mutual inductance value through calculation. According to the method, calculation is performed in strict accordance with a motor classic equivalent circuit model, the accuracy is high, additionally, the condition that a reference voltage output by a motor controller is not accordant with the actual voltage and effects of the skin effect are further considered, corresponding compensation measures are taken, and the parameter identifying accuracy is further improved.

The invention discloses a motor parameter detection method and a motor parameter detection device. The motor parameter detection method comprises the following steps: opening the circuit of one of phase windings of a motor; detecting stator leakage inductance and rotor leakage inductance; applying rated voltage with higher frequency than rated power between the other two phases of the motor; and detecting the stator leakage inductance and the rotor leakage inductance according to the computational formula of the stator leakage inductance and the rotor leakage inductance. The invention provides the off-line motor parameter detection method and the motor parameter detection device under the static condition of the rotor of an induction motor, which achieve high accuracy of motor parameter detection through reducing the influences of voltage errors and a skin effect as long as current or voltage with different frequencies is applied between the two phases of the motor in sequence.

A device and method of commutation control for an isolated boost converter provides a unique commutation logic to limit voltage spikes by utilizing switches on the secondary side to minimize a mismatch between current in the inductor and current in the leakage inductance of the transformer when commutation takes places. To minimize this mismatch, the current in the leakage inductance is preset at a certain level that approaches the current in the inductor prior to the commutation, thus significantly reducing the power rating for a clamp circuit and enabling use of a simple passive clamp circuit. In addition, through unique timing of the turn-on of the secondary switches, soft switching conditions are created that eliminate turn-on losses and the reverse recovery problems of free-wheeling diodes.

The invention discloses an electrolytic capacitor-free LED driving power supply based on flyback converter leakage inductance energy utilization. The power supply comprises an alternative current input power supply, a bridge rectifier circuit, an auxiliary circuit, a main switch tube, a flyback transformer, a rectifier circuit, an output filter capacitor and an LED load. The power supply has the characteristics and advantages that firstly, as energy storage capacitance voltage of the auxiliary circuit is designed into a working mode that direct current voltage is overlapped with large pulse ripple voltage, not only is the dependence of the LED driving power supply on an electrolytic capacitor eliminated, but also flyback converter leakage inductance energy utilization is achieved; secondly, the flyback transformer works in a current interrupted mode, and input power factor correction is achieved; thirdly, due to adoption of the auxiliary circuit, the low frequency pulse power of input power pin and output power po can be balanced, and the constant current can be achieved to drive the LED load through coordination work of the auxiliary circuit and a main circuit.