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197results about How to "Reduce harmonic current" patented technology
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Control system of offshore wind power flexible DC power transmission current transformer
InactiveCN101295877AShort response timeReduce shockSingle network parallel feeding arrangementsWind energy generationElectric power transmissionPower quality
The invention relates to a control system of a flexible wind power DC convertor on the sea, which pertains to the technical field of power transmission in wind power generation and comprises the doubly closed loop control structure of a sending end rectifier on the sea and the doubly closed loop control structure of a receiving end inverter on the coast; the doubly closed loop control structure of the sending end rectifier on the sea is used for controlling the active power of a flexible DC transmission system and the voltage stability of a wind power AC system; the doubly closed loop control structure of the receiving end inverter on the coast is used for controlling the constant voltage of the DC side of a receiving end convertor and the dynamic regulation of the reactive power of the main network accessing end of the receiving end convertor; two control structures are mutually independent and no data communication exists between the two control structures. The control system can fast and correctly control the active power of wind power transmission on the sea as well as promote the stability of the wind power AC system on the sea and the transmission efficiency and the power quality of the whole DC transmission system.
Owner:SHANGHAI JIAO TONG UNIV
Vehicle-to-grid (V2G)-technology-based vehicle-mounted charging and discharging device and control method thereof
InactiveCN102163856AImprove transmission efficiencyZero steady-state error elimination effect is goodBatteries circuit arrangementsAc-dc conversionHysteresisControl manner
The invention relates to a vehicle-to-grid (V2G)-technology-based vehicle-mounted charging and discharging device and a control method thereof. The device comprises a power supply input part, a battery, a power grid side controller, a power grid side converter, a battery side controller and a battery side converter, wherein the power supply input part, the power grid side converter and the battery side converter are connected with the battery in turn; the battery side controller adopts a hysteresis loop comparison control mode and compares voltage and current amount which is detected in real time with the set value, and a duty ratio of the battery side converter is subjected to hysteresis loop output control, so that Boost chopped wave conversion during constant current, constant voltage charging and grid connection is realized; and the power grid side controller adopts a double closed loop control mode of a voltage outer ring and a current inner ring to realize charging adaptation and grid-connected inversion of the power grid side converter. The device overcomes the defects that the traditional bidirectional converter circuit is complex in structure, high in cost and low in efficiency in the V2G technology, and the requirement of operating the same circuit in two working modes is met.
Owner:SOUTHEAST UNIV
Island effect detection method based on active frequency deviation and its device
InactiveCN101123349AAvoid the disadvantages of failureOvercome the disadvantage of extended detection timeEmergency protective circuit arrangementsHarmonicNew energy
A detached island effect test method and a device based on active frequency deviation relate to a test method and a device to test distributive new energy grid integration power supply, in particular to a detached island effect test method and a device based on active frequency deviation. Regarding the utility model, 25 cyclic waves form a major cycle. Chopped wave rate cf of the first 15 cyclic waves is 0, and variance trend of the frequency is tested. Under the circumstance that frequency tends to rise, frequency disturbance with the chopped wave rate of cf is added in the grid frequency in the last ten cyclic waves, and initial value cfmax of the chopped wave rate cf is positive. Under the circumstance that the frequency tends to reduce, frequency disturbance with the chopped wave rate of cf is added in the grid frequency in the last ten cyclic waves, and initial value cfmin of the chopped wave rate cf is negative. By adopting the invention, not only the operation probability of the detached island tested is improved; but also testing time is reduced, and current harmonics injected into the grid is reduced.
Owner:JIANGSU NARI TURBOSTAR ELECTRIC +2
Double three-phase permanent magnet motor vector control method based on proportional resonance regulator
ActiveCN103441726AReduce lossSuppression of current harmonic componentsElectronic commutation motor controlVector control systemsControl vectorResonance
The invention discloses a double three-phase permanent magnet motor vector control method based on a proportional resonance regulator. The double three-phase permanent magnet motor vector control method aims at weakening and eliminating (6m+ / -1)th power of motor harmonic components under double three-phase permanent magnet motor vector control, wherein m=1,3,5.... The double three-phase permanent magnet motor vector control method is characterized in that on the basis of vector space decoupling vector control, a proportional-resonant regulator is adopted to carry out tracking control on the components (isz1 and isz2) on z1-z2 harmonic sub planes after static coordinate transformation is carried out on six-phase electric currents. By the adoption of the double three-phase permanent magnet motor vector control method, optimal control of a double three-phase permanent magnet synchronous motor can be achieved. Compared with traditional double three-phase motor vector control, the double three-phase permanent magnet motor vector control method has the advantages that current wave forms are more sinusoidal, the harmonic content is greatly reduced, especially the (6m+ / -1)th power of the current harmonic components is reduced, system loss is low, and good steady-state performance is achieved.
Owner:ZHEJIANG UNIV
Global synchronization pulse width modulation system and method of distributed grid-connected inverter system
ActiveCN103840485AReduce harmonic currentImprove power qualitySingle network parallel feeding arrangementsPulse duration/width modulationGrid connected inverterPower grid
Owner:SHANDONG UNIV
Energy-feedback tractive power supply system with high power factor and high cost performance
InactiveCN102328601AAchieving two-way flowSave electricityPower supply linesSingle network parallel feeding arrangementsContact networkRing network
The invention discloses an energy-feedback tractive power supply system with high power factor and high cost performance, relating to an energy-feedback tractive power supply system. The system comprises a main substation, a medium-voltage ring network, a first to an Nth energy-feedback tractive substations, a direct-current contact network and a steel rail. In the energy-feedback tractive substations, a set of 12-pulse-wave rectifier unit and a set of PWM (Pulse Width Modulation) unit are connected in parallel; by sufficiently utilizing respective advantages of the rectifier unit and the PWM unit, bidirectional flow of energy is realized on the one hand, braking energy of a train is fed back to an alternating-current grid, and electric energy is saved; on the other hand, the energy-feedback tractive power supply system integrates the advantages of simpleness and reliability, low cost and strong overload capability of a diode rectifier unit; beside, certain sensitive and capacitive reactive power is injected into the medium-voltage ring network by utilizing the PWM rectifier unit, and the power factor at the alternating-current incoming line of the main substation can be greatly increased. The whole tractive power supply system has higher cost performance.
Owner:BEIJING QIANSIYU ELECTRIC +1
High-power bidirectional multi-way direct-current simulation power supply
InactiveCN104868755AVersatileFunction increaseAc-dc conversion without reversalDc-dc conversionEngineeringConductor Coil
The invention discloses a high-power bidirectional multi-way direct-current simulation power supply. The high-power bidirectional multi-way direct-current simulation power supply is characterized by consisting of at least two mutually insulated simulation direct-current power supply units, wherein each simulation direct-current power supply unit comprises an AC / DC converter and a DC / DC converter which are connected in series; an input end of each AC / DC converter is connected with a secondary side winding of an input transformer; an input end of each DC / DC converter is connected with a capacitor in parallel, and a positive electrode of an output end of each DC / DC converter is connected with a diode in series; two ends of each diode are respectively connected with a switch in parallel. The high-power bidirectional multi-way direct-current simulation power supply is universal in function, only needs to adopt different control strategies, can widen the functions without replacing hardware, and solves the problems of high testing cost of existing DC equipment, small capacity, difficulty in expansion, single voltage level and functions and the like.
Owner:江苏同芯电气科技有限公司 +1
Control method for bidirectional quasi-Z-source inversion type motor driving system
ActiveCN105897099AAchieving two-way flowCapable of boostingElectronic commutation motor controlAC motor controlCapacitanceLoop control
The invention relates to a control method for a bidirectional quasi-Z-source inversion type motor driving system. The control method comprises the following steps of collecting the voltage of a capacitor C2 and the current of a permanent magnet synchronous motor; obtaining voltage components of a d axis and a q axis; obtaining a direct-connection duty ratio; carrying out an SVPWM (space vector pulse width modulation) algorithm by inserting the direct-connection duty ratio according to the voltage components of the d axis and the q axis and the direct-through duty ratio to obtain six paths of PWM control signals for controlling the on and off of three-phase bridge arms of a three-phase bridge type inverter; and carrying out logic calculation on the six paths of PWM control signals to output a PWM control signal for controlling the on and off of an IGBT switch tube S7. Compared with the prior art, the average direct-connection duty ratio and the capacitor voltage closed loop control closed loop policy are added to the conventional SVPWM control method, so that the direct current side voltage has the voltage boosting capability; and on the basis, the power switch S7 which is complementary with the direct-connection state is further designed, so that the bidirectional flow of energy can be realized.
Owner:TONGJI UNIV
Control device and control method for AC-DC (Alternating Current-Direct Current) series resonant matrix converter for capacitor charging
ActiveCN103078522ASmall sizeReduce weightAc-dc conversion without reversalEfficient power electronics conversionCapacitanceMatrix converters
The invention discloses a control device and a control method for an AC-DC (Alternating Current-Direct Current) series resonant matrix converter for capacitor charging and mainly aims at solving the problem in the prior art that the control property of a capacitor charging power supply is not high enough to meet the power supply requirement of a high-power microwave system. The control device for the AC-DC (Alternating Current-Direct Current) series resonant matrix converter for capacitor charging comprises a zero-crossing comparator, an On-Off state control unit, a timing sequence generating unit, a control parameter calculation unit, a load voltage acquisition circuit and a trigger driving circuit. The invention further discloses a control method of the control device. With the technical scheme, the control device and the control method, disclosed by the invention, have the advantages that the price / performance ratio is relatively high property, the power supply requirement of the high-power microwave system can be sufficiently met, and the practical value and the popularization value are high.
Owner:SOUTHWEST JIAOTONG UNIV +5
Stator and rotor combined structure
ActiveCN105186816AReduce torque rippleReduce harmonic currentMagnetic circuit rotating partsSynchronous machines with stationary armatures and rotating magnetsAxis of symmetryConductor Coil
The invention discloses a stator and rotor combined structure and belongs to the motor field. The stator and rotor combined structure includes a stator and a rotor; the stator includes a stator core; the stator core is provided with wire winding teeth opposite to the rotor; the wire winding teeth are uniformly distributed on the stator core; the wire winding teeth are wound with an armature winding; the rotor includes a rotor core and a plurality of magnets; a plurality of mounting grooves are uniformly distributed at intervals along the circumferential direction of the rotor core; one magnet is embedded in a corresponding mounting groove; the plurality of magnets include first magnets and second magnets, wherein the first magnets are adjacent to the second magnets; the axis of symmetry of the first magnet, which passes through the center of the rotor is a D axis; an axis of symmetry between the first magnet and the second magnet, which passes through the center of the rotor is a Q axis; the distance from points on the outer contour line of an end surface of the rotor to the side walls of the wire winding teeth is g; and in a sector scope from the Q axis to the D axis, g is decreased from the Q axis to the D axis.
Owner:BERGSTROM CHINA GRP
Charging and discharging control system and method of flywheel battery
InactiveCN102075138AReduce harmonic currentDC voltage stabilityElectronic commutation motor controlAC motor controlOvervoltageSignal processing circuits
The invention discloses a charging and discharging control system and a charging and discharging control method of a flywheel battery. The system comprises a three-phase uncontrollable rectifying circuit, an energy storage filter capacitor, an insulated gate bipolar translator (IGBT) power conversion circuit, a zero passage detection circuit, a voltage detection circuit, a current detection circuit, a direct current voltage detection and overvoltage protection circuit, a sampling and filtering overcurrent protection circuit, a displacement sampling circuit, a temperature sampling circuit, a digital signal processor controller, an energy storage inductor, a three-phase linked switch and a rotary transformer signal processing circuit, wherein the energy storage inductor is connected between the output end of each phase on the alternating current side of the IGBT power conversion circuit and the input end of a flywheel motor; the three-phase linked switch is connected in parallel with the energy storage inductor respectively; and the rotary transformer signal processing circuit is connected between the signal output end of a rotary transformer of the flywheel motor and the quadrature encoder pulse (QEP) port of the DSP controller. In the method, charging and discharging control of a flywheel battery is realized based on the system. The system has stable output direct current voltage, small high-frequency ripple, quick dynamic response, and is particularly suitable for quick charging and quick discharging working conditions; and the power factor and efficiency of the system are improved greatly.
Owner:深圳飞能能源有限公司
Large capacity cascade multi-phase multi-level power converter without transformer
ActiveCN101483392AReduce weightReduce volumeAC motor controlConversion with intermediate conversion to dcCapacitanceTransformer
The present invention discloses a large-capacity cascades multiphase multi- electrical level power converter without transformer, which belongs to high pressure large-capacity multiphase multi- electrical level frequency conversion technology field, and characterized in that a single-phase main circuit is composed by identical prime power convert unit through cascades; three single-phase main circuits are connected to the three phase electric network through star or triangle shape; the prime power convert unit constitutes 'back to back' AC-DC-AC inverter circuit topology through DC bus capacitance with multiphase inverter by H-type rectifying bridge; different electrical level, types, number of phases and connecting relation of the prime power convert unit can extends various different polyphase converter practical topology circuit, which saves phase-shifting transformer that original absolutely necessarily but volume weight covers more than one third of that of system, which reduces greatly volume and cost of complete appliance. The present invention is capable of realize high performance operation of speed governing system in four quadrant scope, can feedback energy from the electric motor to the electric network when the electric motor brakes, enhances working condition operation efficiency of speed governing system; and communicate electric network side current harmonics small and power factor close to 1.
Owner:TSINGHUA UNIV
Method for compensating three-phase unbalanced currents on basis of SVG (static var generator)
ActiveCN106300399AImprove detection accuracyDetection speedPolyphase network asymmetry elimination/reductionPolyphase network asymmetry reductionPhase lockingPower grid
The invention relates to a method for compensating three-phase unbalanced currents on the basis of an SVG (static var generator). The method includes determining whether load currents needs to be compensated or not via three-phase unbalanced judging links by the aid of load current signals which are used as control input; acquiring frequencies and phases of power grid voltages via adaptive frequency locking and phase locking links when the load currents need to be compensated; filtering harmonic current components in the load currents by the aid of discrete second-order generalized integrators; computing negative-sequence current values required to be converted for various phases if the three-phase unbalanced currents are in balanced states; transmitting the negative-sequence current values to control instruction computation modules in SVB devices; driving IGBT (insulated gate bipolar transistors) to act; generating currents equal to fundamental negative-sequence components in the load currents so that the three-phase unbalanced currents can be in the balanced states. The negative-sequence current values are used as reference current signals. The directions of the currents are opposite to the directions of the fundamental negative-sequence components in the load currents. The method has the advantages that the three-phase unbalanced currents can be dynamically compensated, and accordingly the stability and the reliability of power grids can be improved; low-pass filters can be omitted when negative-sequence currents are extracted, and accordingly the method is low in computational burden and high in response speed and tracking precision.
Owner:QINGDAO TOPSCOMM COMM
Method and system for controlling current of grid-side converter of wind driven generator under unbalanced power grid condition
InactiveCN102694394AControls are simple and straightforwardInductance changes have little effectSingle network parallel feeding arrangementsWind energy generationWind drivenPower factor
Disclosed are a method and a system for controlling current of a grid-side converter of a doubly-fed wind driven generator under an unbalanced power grid condition. The method includes combining voltage of a power grid, alternating-current-side voltage of the grid-side converter and delay signals of the power grid and the grid-side converter with given active power and given reactive power, and analyzing and computing to obtain an instruction value of alternating-current-side current of the converter; and further computing to obtain alternating-current-side instruction voltage of the grid-side converter according to a mathematic module of the grid-side converter and a principle that an actual current value of a next time interval is equal to the instruction value, and then generating a pulse signal for controlling on and off of a switching tube via SVPWM (space vector pulse width modulation). In the method, rotational coordinate transformation and positive and negative sequence decomposition are not required, grid-side current and inductance parameters are either not required, fluctuation of direct-current-side voltage of the grid-side converter can be suppressed under an unbalanced voltage condition of the power grid, grid-side harmonic current is reduced, and unity power factor is maintained.
Owner:NORTH CHINA UNIVERSITY OF TECHNOLOGY
Charging pile, charging system and charging control method
PendingCN106451710AImprove power factorReduce harmonic currentBatteries circuit arrangementsCharging stationsThree levelEngineering
The invention provides a charging pile, a charging system and a charging control method, and belongs to the technical field of power electronics. The charging pile comprises a power conversion circuit and a sampling circuit, wherein the power conversion circuit comprises a three-phase three-level power factor corrector and an interleaved buck chopping converter; the input end of the three-phase three-level power factor corrector is connected with a three-phase power grid, and the output end of the three-phase three-level power factor corrector is connected with the input end of the interleaved buck chopping converter; and the output end of the interleaved buck chopping converter is used for connecting a charging gun. The power conversion circuit can be used for improving the power factor on the alternating current input side and reducing the harmonic current and harmonic voltage of charging; and a switching pipe in the power conversion circuit has small voltage stress and small current stress. The charging pile provided by the invention is a power grid-friendly charging pile.
Owner:HUBEI UNIV OF ARTS & SCI
DC Power Supply Unit and Air Conditioner Using Same
ActiveUS20170070157A1Improve efficiencyReduce harmonic currentAc-dc conversion without reversalEfficient power electronics conversionMOSFETAC power
A DC power supply unit is provided that allows for improving efficiency and reducing harmonic currents. A DC power supply unit includes: a bridge rectification circuit having diodes and MOSFETs; a reactor that is arranged between the AC power supply and the bridge rectifier circuit; a smoothing capacitor that is connected to an output side of the bridge rectifier circuit and smoothes a voltage; and a converter control unit that executes, based on predetermined threshold values, a diode rectification control that uses diodes and parasitic diodes of the MOSFETs, a synchronous rectification control that switches the MOSFETs in synchronization with a polarity of the voltage of the AC power supply, a partial switching control that repeats partially short-circuiting the reactor multiple times in a half cycle of the AC power supply, or a fast switching control that short-circuits the reactor at a predetermined frequency over a full AC cycle.
Owner:HITACHI JOHNSON CONTROLS AIR CONDITIONING INC
Multiple-voltage power supply for railway vehicle
InactiveCN1543406AReduce harmonic currentPropulsion using ac induction motorsRailway vehiclesCapacitanceTransformer
The invention concerns an installation constituting a railway propulsion chain, characterized in that it comprises, sequentially arranged, in the power electrical circuit, between a power transformer powered by a catenary and an electric motor of said vehicle, said catenary being capable of supplying a plurality of voltages, alternating or direct, said electrical circuit comprising a plurality of contact switches for selecting a given catenary voltage, at least one of the following elements: a controlled rectifier bridge (A1, A2), preferably a single-phase bridge with forced switching; a substantially reactive input filter (A3), preferably comprising at least a capacitance and / or at least an induction coil; a braking chopper capable of including also a clipping function (B); a multiphase and multilevel static converter (C1, C2, C3), preferably three-phase; electronic components, preferably IGBT power semiconductors for each element, each element belonging to at least an elementary power arm of the modular circuit diagram.
Owner:ALSTOM BELGIUM SA
Method for controlling network side rectifier of brushless double-feed wind-driven generator under unbalanced electric network
InactiveCN102655332AControls are simple and straightforwardSuppresses DC output voltage fluctuationsSingle network parallel feeding arrangementsWind energy generationWind drivenDecomposition
The invention discloses a method for controlling a network side rectifier of a tandem type brushless double-feed wind-driven generator under an unbalanced electric network, and aims to calculate given compensation values of active and reactive powers on a static coordinate system according to electric network voltage, delayed signals and active and reactive initial given values. The summation of the active and reactive initial given values and the given compensation values is a final power instruction value which is taken an unbalanced condition of the electric network voltage into account, then alternating-current side instruction voltage is calculated according to a mathematical model of the network side rectifier, and a driving signal of a switching device is obtained by using space vector pulse width modulation (SVPWM) decomposition. According to the method, transformation of rotational coordinates and decomposition of positive and negative sequence components are not required, second harmonic fluctuations of direct-current side voltage of the network side rectifier when the electric network voltage is unbalanced can be inhibited, and the network side harmonic current is reduced.
Owner:NORTH CHINA UNIVERSITY OF TECHNOLOGY
DC power supply apparatus
InactiveUS8937821B2Improve efficiencyReduce harmonic currentAc-dc conversion without reversalEfficient power electronics conversionGallium nitrideAC power
A DC power supply apparatus comprising: a rectifying circuit including, a first rectifying portion, a second rectifying portion, a third rectifying portion and a fourth rectifying portion; a current detection portion; a first switching portion; and a second switching portion; wherein each of the first rectifying portion cooperatively operating with the first switching portion and the second rectifying portion cooperatively operating with the second switching portion is a semiconductor element which is formed by using a Schottky junction formed between silicon carbide or gallium nitride and metal and has a withstanding voltage property with respect to a voltage of an AC power supply.
Owner:AUTO TECH GRP LLC
Novel rotating rectifier with fault monitoring function
InactiveCN106849702AImprove reliabilityAvoid current harmonicsVector control systemsEfficient power electronics conversionSynchronous motorBusbar
The invention provides a novel rotating rectifier with a fault monitoring function, and relates to rotating rectifying systems. The invention aims at solving the problems that an existing rectifier is low in output power of an alternating-current exciter and high in harmonic component, a rotating rectifying controller cannot be timely started and a system fault exists. The novel rotating rectifier with the fault monitoring function comprises a three-phase triple voltage rectifying circuit, an alternating-current exciter, a rotating bridge rectifier module based on VIENNA, a start power module, a start resistor, a rotating rectifying controller, a synchronous electric exciter set, a fault detection module, a wireless communication device, a first wireless transceiving device, a second wireless transceiving device and an external monitoring module. According to the novel rotating rectifier with the fault monitoring function, a neutral-point potential balance method of injecting zero-sequence voltages is adopted, zero-sequence voltages VZ(+) and VZ(-) are injected into a three-phase reference voltage at different moments, and the problem is solved that two capacitor voltages of a direct current busbar are not balanced.
Owner:HARBIN UNIV OF SCI & TECH
Virtual flux-based dual-PWM frequency converter model prediction direct power control method
InactiveCN108011553ASimple structureReduce design costElectronic commutation motor controlAC motor controlAlternating currentFlux linkage
Disclosed is a virtual flux-based dual-PWM frequency converter model prediction direct power control method. The method comprises the steps of collecting three-phase alternating current power grid voltages e<sa>, e<sb> and e<sc>, rectifier grid side three-phase line currents i<sa>, i<sb> and i<sc>, a direct current bus voltage u<dc>, and three-phase stator currents i, i and i<c>; enabling adifference value between the direct current bus voltage u<dc> and a given direct current bus voltage u<dcref> to pass through a PI regulator to obtain a given load current I<dcref>; enabling the givenload current to be multiplied with the direct current bus voltage to obtain given active power p<ref>, wherein the given reactive power q<ref> is equal to 0; obtaining instantaneous active power andinstantaneous reactive power according to the components of the rectifying side three-phase alternating current voltages and three-phase line currents in an alpha-beta coordinate system and by virtueof the virtual flux <Psi><s>, and solving power differential, and obtaining active and reactive prediction values before the next period is started according to a one-order linear equation; and enabling the inversion side to perform conversion of coordinates according to a rotor flux orientation vector control strategy so as to realize full decoupling of the motor torque and flux control. By virtue of the method, the dynamic response speed of the system is improved, the anti-disturbance performance of the system is improved, and the frequency conversion system has higher advantages.
Owner:CHINA THREE GORGES UNIV
Hybrid driven low harmonic inversion control method and modulation mode switching circuit thereof
InactiveCN102710159ASimple structureLow costDc-ac conversion without reversalGrid connected inverterHarmonic
The invention discloses a hybrid driven low harmonic inversion control method and a modulation mode switching circuit thereof. An inversion control technology of monopolar modulation and ambipolar modulation is used in one sinusoidal period in a mixed way, the ambipolar modulation is used in intervals before and after the zero crossing point of the sinusoidal period, and the monopolar modulation is used in other intervals of the sinusoidal period, the time ratio of the monopolar modulation to the ambipolar modulation in one sinusoidal period is controlled by setting different control parameters, under the condition of the same control parameter and circuit parameter, and the voltage or current harmonics output by the inverter can be effectively reduced. The invention is especially suitable for the grid-connected inverter control in renewable energy sources.
Owner:SOUTHEAST UNIV
Three-level active triple harmonic injection matrix converter with T-shaped structure
ActiveCN107196523ARealize power bidirectional flow functionReduce harmonic currentAc-dc conversionAc-ac conversionThree levelMatrix converters
The invention provides a three-level active triple harmonic injection matrix converter with a T-shaped structure. The three-level active triple harmonic injection matrix converter comprises a rectification-stage circuit, a triple harmonic injection circuit, an inversion-stage circuit and an input LC filter, wherein the rectification-stage circuit is used for rectifying an alternating current input from a three-phase AC input voltage provided by a three-phase AC power supply to a six-pulse DC voltage, the triple harmonic injection circuit is used for generating triple harmonic from a direct current and injecting the triple harmonic to the rectification-stage circuit, the inversion-stage circuit is used for converting the direct current to the alternating current, and the input LC filter comprises a filtering inductor and a filtering capacitor and is used for filtering and providing a neutral point of an inversion stage in the inversion-stage circuit. The three-level active triple harmonic injection matrix converter has the advantages of better control performance, lower common-mode level and higher system efficiency, the control range of input reactive power is expanded, synchronous modulation is not needed, higher output power quality is also provided, and an output waveform is improved.
Owner:CENT SOUTH UNIV
On-line dynamic harmonic treatment device
InactiveCN101989746AImprove transmission performanceReduce active lossReactive power adjustment/elimination/compensationReactive power compensationHarmonicPower factor
The invention relates to an electronic device, in particular to an on-line dynamic harmonic treatment device which comprises a bus, a harmonic detection loop, a power supply transformation loop, an IGBT (Insulated Gate Bipolar Translator) inverter and a main loop. When current passes through the bus, the harmonic detection loop detects the power factor and the harmonic current of a power grid, and the IGBT inverter can generate a capacitive current having the same magnitude and a different direction compared with the current of the bus for the power grid to eliminate electronics. In the invention, the electronic detection loop only works when current passes through the bus, thus lagging conditions cannot occur, and the whole regulating speed is lower than 10ms.
Owner:国网南自控股(杭州)有限公司
Rectifier circuit
The invention relates to a rectifier circuit, comprising two inductors L1 and L2, a first switch element Q1, a second switch element Q2, a third switch element Q3, three diodes D3, D4 and D5, and two capacitors DC1 and C2, wherein one end of the inductor L1 is connected with a fire wire and the other end thereof is connected with the cathode of the diode D3, one end of the capacitor DC1 and one end of the third switch element Q3 simultaneously by the first switch element Q2; the other end of the inductor L1 is connected with the anode of the diode D4, the other end of the capacitor DC1 and the anode of the diode D5 simultaneously by the second switch element; the anode of the diode D3 and the cathode of the diode D4 are connected with the zero line simultaneously; the cathode of the diode D5 is connected with the other end of the third switch element Q3; furthermore, the inductor L2 is connected in series with the capacitor C2 and is then connected in parallel to the diode D5. The rectifier circuit can greatly reduce the harmonic current and improve the circuit power factor; furthermore, compared with the output voltage, the input voltage can be output in a reducing or boosting way.
Owner:SHENZHEN SINEXCEL ELECTRIC
Dimension reduction observer design method based on grid-connected LCL filter system
InactiveCN105449677AImprove reliabilityReduce harmonic currentSingle network parallel feeding arrangementsHarmonic reduction arrangementCapacitanceEngineering
The invention discloses a dimension reduction observer design method based on a grid-connected LCL filter system. An active damping control method based on a state observer is disclosed. Through feedforward, a capacitance current is observed so as to restrain a system resonance. For a completely observable system, a system can be reconstructed, a variable which can be directly measured in an original system, such as an input quantity and an output quantity, is used and taken as an input signal so that the output quantity is equivalent to a state variable of the original system under a certain index. After observability analysis is performed on the grid-connected LCL filter system and the system is demonstrated to be the completely observable system, through the input quantity and the output quantity of the LCL filter system, the system state variable is estimated so that purposes of saving an additional sensor and increasing system reliability are reached. In the invention, an LCL grid-connected inverter based on a dimension reduction observation method can effectively carry out grid connection on an intermittent power generation system, active and reactive power control is performed on a network-access current, and simultaneously and more importantly, a harmonic current can be reduced.
Owner:STATE GRID TIANJIN ELECTRIC POWER +1
Interlacing power-factor correction circuit and control method thereof
ActiveCN104868709AImprove reliabilityReduce harmonic currentEfficient power electronics conversionPower conversion systemsVoltage referenceEngineering
The invention discloses a control method of an interlacing power-factor correction circuit, and an interlacing power-factor correction circuit with the control method. The control method comprises the following step: sampling voltage values which are input to a plurality of boost branches by a rectifying circuit, sampling a total output voltage value of the plurality of boost branches; sampling a total input current value of the plurality of boost branches, sampling a current value of each boost branch in operation; according to the voltage values, the total output voltage value, the total input current value, and a preset output voltage reference value, calculating a total current reference value, and distributing the total current reference value equally to obtain a current reference value output to each boost branch, and according to the current reference values and the sampled current value of corresponding boost branches in operation, adjusting PWM control signals output to a switch tube of a corresponding boost branch. The control method effectively solves a problem of unbalance current of the interlacing power-factor correction circuit, and reliability of the circuit is improved.
Owner:GD MIDEA HEATING & VENTILATING EQUIP CO LTD +1
Brushless DC (direct current) motor 180-degree square wave control method and module and converter
ActiveCN103647482AEasy to controlReduce harmonic currentAC motor controlSingle motor speed/torque controlFrequency changerThree phase windings
The invention discloses a brushless DC motor 180-degree square wave control method and module and a converter. The control method comprises the following steps of obtaining an inverter input voltage Udc, phase currents ia, ib and ic of the brushless DC motor, an actual rotational speed omega and a rotor position; calculating a given torque current I* according to omega and a given rotational speed omega*; calculating three-phase given phase currents i*a, i*b and i*c of the motor according to the I* and the rotor position; calculating three-phase phase voltages U*a, U*b and U*c of the motor according to i*a, i*b and i*c and ia, ib and ic; calculating the three-phase opposite potential ea, eb and ec of the motor according to the rotor position and omega; adding U*a, U*b and U*c to ea, eb and ec respectively to obtain the compensated phase voltages Ua, Ub and Uc; calculating a duty ratio of a three-phase SPVWM (Space Vector Pulse Width Modulation) signal input to the inverter according to Udc and Ua, Ub and Uc. The brushless DC motor 180-degree square wave control method and module and the converter can achieve the effect that the waveform of the current of every phase is a square wave under the condition that three-phase windings of the brushless DC motor stator work simultaneously.
Owner:SHANGHAI STEP ELECTRIC +1
Hybrid intelligent adjusting method of torque hysteresis width in DTC (Direct Torque Control) system
InactiveCN102522948AReduce switching lossesReduce noiseElectronic commutation motor controlAC motor controlHysteresisLow speed
The invention discloses a hybrid intelligent adjusting method of torque hysteresis width in a DTC (Direct Torque Control) system. According to the hybrid intelligent adjusting method, with speed change and stator current change as input signals and increment of the torque hysteresis width as an output signal, a dynamic and adjustable torque hysteresis width value is obtained on the basis of determining a torque hysteresis width basic value, and the torque hysteresis width value changes along with the change of the control process; and the hybrid intelligent adjusting method has stronger adaptability and overcomes the defect that the torque hysteresis width is set into a fixed value in the conventional technology. The hybrid intelligent adjusting method disclosed by the invention has the beneficial effects that: the harmonic content in current is weakened, minimum values of flux linkage and torque pulse of an induction motor are obtained, and noise and vibration of the induction motor are reduced; the problems of high torque pulse and existence of speed steady-state error and periodic pulse of the rotating speed, of the induction motor under the low-speed operation condition, are solved; and the induction motor can obtain a smooth and effective driving performance. Therefore, the hybrid intelligent adjusting method is a fuzzy-neural-network hybrid intelligent control mode with high performance.
Owner:CHONGQING JIAOTONG UNIVERSITY
Method for increasing permanent-magnet synchronous linear motor dynamic control performance
ActiveCN108054972AImprove dynamic control performanceReduce harmonic currentTorque ripple controlAC motor controlMathematical modelPredictive controller
The invention discloses a method for increasing permanent-magnet synchronous linear motor dynamic control performance. The method comprises the following steps of firstly, hypothesizing a discrete mathematic model of a permanent-magnet synchronous linear motor control system electric current loop; then, based on the above discrete mathematic model, recursing a predicted value of a state variable in a prediction domain; and finally, using a permanent-magnet synchronous linear motor stator voltage equation in a synchronous rotating coordinate of rotor magnetic field orientation, through controlling and predicting a controller output voltage U(k), making an actual sampling current i(k+1) at a k+1th moment be equal to a target current i<*>(k+1) predicted and acquired at a kth moment and dead-beat control is realized . By using the method of the invention, problems that a traditional electric current loop PI regulator is strongly dependent on motor parameters and is difficult to satisfy a high performance control requirement of a servo system are solved; and a permanent-magnet synchronous linear motor control method based on dead-beat current prediction control is selected so that a current harmonic wave and a torque ripple are reduced and system dynamic performance is increased.
Owner:XIAN UNIV OF TECH
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