21results about How to "Reduce Harmonic Distortion Rate" patented technology

The invention relates to a distributed photovoltaic power station main converter and a control method thereof, and belongs to the field of photovoltaic power generation. The main current transformer comprises a T-type three-level current transformer and a Buck-Boost current transformer; the T-type three-level converter comprises three bridge arms, two output capacitors and the like; each bridge arm is provided with four power switch tubes; the two output capacitors are connected in series, and the connection point is called as the midpoint O of the T-type three-level converter. And one end of a direct-current inductor of the Buck-Boost converter is connected with the midpoint O. The T-type three-level converter adopts PI control and a carrier pulse width modulation strategy to realize alternating current side current harmonic wave minimization of the T-type three-level converter; the Buck-Boost converter adopts a PI control method to realize neutral-point potential automatic balance control. The method is small in current harmonic wave, low in cost and simple to control, and can realize quick and automatic balance of the neutral-point potential, thereby effectively coping with the influence of illumination and power grid voltage fluctuation on system control, and realizing quick and stable control of the distributed photovoltaic power station.

The invention relates to a compact railway energy regulation and control complex which comprises a converter unit with an intermediate frequency transformer as a core, and an alternating current port of each converter unit is connected with buses of alpha and beta phase traction feeder lines on the secondary side of a V / v traction transformer in series. A magnetic field hedging decoupling inductor and a filter capacitor of the medium-frequency transformer form a secondary harmonic filter branch on the direct current side of each converter unit, non-negligible secondary harmonic components on the direct current side of each converter unit in the single-phase converter system are filtered out, and a power winding of the medium-frequency transformer is connected with a DC / DC converter on the inner side of each converter unit. The compact railway energy regulation and control complex can accurately control the tidal current distribution of the two power supply arms, carries out comprehensive energy regulation and control through a direct current port and an external energy storage and new energy power generation system, can effectively inhibit the voltage fluctuation of a feeder line side, improves the comprehensive energy utilization rate and the new energy consumption rate of an electric railway system, and improves the energy utilization rate of the electric railway system. Compensating the power factor of the high-voltage side of the transformer substation and inhibiting the voltage unbalance degree of the PCC point.

The invention provides a novel high-power low-ripple-output hydrogen production converter and a control method. The novel high-power low-ripple-output hydrogen production converter comprises a six-pulse conversion unit, a filter circuit and a three-phase stacked interleaved Buck circuit. The six-pulse commutation unit is connected in series with the filter circuit, then is connected in series with the three-phase stacked interleaved parallel Buck circuit 3, and finally is connected with a load. And the direct-current voltage of the converter is changed by controlling the phase of the trigger pulse of the thyristor valve so as to realize six-pulse direct-current power transmission. The main branch of the three-phase stacked interleaved parallel auxiliary branch is used for realizing power transmission, and the auxiliary branch is used for eliminating output current ripples. A voltage-current double closed-loop control strategy can ensure that each phase of the main branch realizes a good current sharing effect; alternating current component complementation and ripple complementation of the current IAX and the current IdcMain can be achieved by controlling the auxiliary branch switching tubes SAX1 and SAX2, then zero ripple of the output current Idco of the converter is achieved, and control over the auxiliary branch is completed. According to the invention, high-power low-current ripple output can be realized in a low-voltage high-current scene.

The invention discloses a photovoltaic grid-connected inverter and a modulation method and device thereof, a medium, equipment and a product, the inverter comprises a direct current source, an inverter network, a filter inductor and a power grid, and the inverter network comprises a flying capacitor, a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube and a fifth power switch tube; the positive electrode of the DC source is connected with the collectors of the first power switch tube and the third power switch tube, and the negative electrode is connected with the emitter of the second power switch tube, the collector of the fifth power switch tube and the power grid. The positive electrode of the flying capacitor is connected with the emitter of the first power switch tube and the collector of the second power switch tube, and the negative electrode is connected with the emitter of the third power switch tube, the collector of the fourth power switch tube and the filter inductor. Through insertion of a fifth power switch tube and a flying capacitor, when the photovoltaic grid-connected inverter is in a follow current mode, a direct current source and an alternating current power grid are decoupled, and common-mode voltage is kept unchanged to suppress leakage current.

The invention provides a coil winding wiring structure, a wiring method and a three-phase motor, and relates to the technical field of motors, the coil winding wiring structure comprises double-layer windings arranged in 72 stator slots of the motor, the double-layer windings comprise an A-phase winding, a B-phase winding and a C-phase winding, and the A-phase winding, the B-phase winding and the C-phase winding are combined in a variable pitch combination mode of 1-10, 1-13 and 1-14. Four-path parallel winding wiring of a 72-slot 6-pole three-phase motor is realized, the limitation of the number of parallel branches in the traditional design is broken through, and the use requirement of a high-performance motor can be met; moreover, each phase of coil is distributed in a stator slot according to a specified pitch, and the number of coils of each pitch is ensured to be consistent among each phase, so that the balance of three-phase resistance is ensured, the slot current can be improved, the distribution uniformity of an internal magnetic field of the motor can be improved, the harmonic distortion rate can be reduced, and the service life of the motor can be prolonged. And the efficiency and the stability of the motor in the operation process are improved.

The invention relates to a chained SVG control system and a configuration method thereof, and belongs to the technical field of power electronics. The method is used for configuring a chained SVG control system of which a controller adopts a heterogeneous dual-core processor architecture based on an FPGA (Field Programmable Gate Array), and comprises the following steps: a control algorithm in the chained SVG control system is realized by an FPGA core, and a control logic in the chained SVG control system is realized by another core; the control algorithm comprises a virtual synchronous control function, commutation chain voltage sharing, control instruction generation and harmonic suppression; the control logic comprises chain type SVG control system start-stop control, unlocking and locking sequence control logic, chain type SVG control system state conversion and main and standby system switching. The control system comprises the controller, the controller adopts a heterogeneous dual-core processor architecture based on the FPGA, and the controller is configured by adopting the method. According to the method, on the premise that control hardware configuration is not changed, the execution time of a control algorithm is greatly shortened, and the cost is low while the control capability of the controller is improved.

This invention discloses a method for adjusting the operating mode of a floating multi-energy complementary power generation platform system. The method includes setting the wave energy generation unit to MEC mode; setting the photovoltaic power generation unit to MPPT mode; setting the grid-side inverter unit to current source mode (VOC control mode); setting the energy storage unit converter to power generation fluctuation smoothing mode, and switching the charging and discharging states of the energy storage unit through constant power control; setting the wave energy generation unit to MEC mode or shutdown operation mode; setting the photovoltaic power generation unit to MPPT mode or constant voltage control mode; setting the grid-side inverter unit to VF control mode; and setting the energy storage unit converter to DC bus voltage stabilization control mode. This invention reduces transmission losses while minimizing the power impact on the main grid during the grid-connected operation of the island microgrid based on the power generation platform, thus improving the system's operational reliability.

The present invention provides a three-phase current type rectifier power supply control method and system for hydrogen production by electrolysis of water, and relates to the field of power supply control. The method comprises: sectorizing a three-phase input voltage signal to obtain an initial even sector signal and an initial odd sector signal; calculating the number of carrier cycles in the initial even sector signal and the number of carrier cycles in the initial odd sector signal to determine a target carrier frequency; determining an even sector extension time based on the target carrier frequency to generate a target even sector signal and a target odd sector signal, thereby generating a triangular carrier signal; generating a switch drive signal of a three-phase current type rectifier power supply based on the triangular carrier signal and a modulation wave obtained based on the three-phase input voltage signal, and having the advantages of eliminating the distortion of the input current of the three-phase current type rectifier power supply at the sector switching point, reducing the harmonic content of the input current, reducing the output current ripple, and improving the efficiency of the rectifier power supply.

The present application relates to a kind of functionization outer diameter unequal thickness magnetic ring and its magnetizing method, belong to permanent magnet motor technical field, the inner diameter of unequal thickness magnetic ring is circular, and the outer diameter is change curve, wherein, the change curve of outer diameter is constant in main magnetic pole portion thickness, and the thickness is reduced in the transition position between adjacent main magnetic pole portion;The unequal thickness magnetic ring adopts bonded neodymium iron boron material.The present application is composed of a functionization outer diameter bonded neodymium iron boron magnetic ring and its matching multipole magnetizing fixture, wherein the outer diameter of magnetic ring adopts two kinds of functionization size, by reducing the thickness of magnetic pole transition area, the harmonic component of surface magnetism of magnetic ring is controlled, and the amplitude of cogging torque is reduced.The multipole magnetizing core of matching magnetizing fixture can magnetize magnetic ring into surface alternately distributed multiple magnetic poles.

The invention discloses a control method and system of a three-phase three-level AC / DC converter. A multi-parallel quasi-resonance PR control method based on time delay phase compensation is adopted in the main body control link, time delay is converted into fixed phases needing to compensate fundamental waves and high order, and the influence of time delay between sampling and output on the system is improved. Aiming at the frequency fluctuation condition of the power grid side, the real-time frequency of the power grid is updated in real time through DSOGI-FLL, a frequency value is transferred to a phase compensation link, the compensation link is calculated through a new frequency value, a new transfer function is obtained after new parameter values are calculated, the new transfer function is connected into a main body control link in series, and the self-adaptive adjustment effect is achieved.

The application discloses a three-phase E-type hybrid level double-output integrated converter and a carrier PWM modulation method thereof, and belongs to the technical field of power electronic conversion devices. The three-phase E-type hybrid level double-output integrated converter comprises one DC input power supply, two capacitors on the DC input side, 15 switch modules, and one set of three-phase inductive load on each output end of the bridge arm of each phase. The carrier PWM modulation method with added DC offset and zero sequence component is given for the proposed converter. Two sets of modulation waves with added DC offset and zero sequence component are compared with anti-phase stacked carriers respectively. According to the switch state and the comparison result, the logic operation for generating the driving signals of each switch module is derived. One set of DC input voltage is converted into three-level AC voltage on the upper end and two-level AC voltage on the lower end through the inverter circuit, and the frequency and amplitude of the three-phase AC voltage can be adjusted. The three-phase E-type hybrid level double-output integrated converter can be widely applied to the double-motor driving application scene of one master and one slave, and has the advantages of reasonable structure, scientific modulation method, outstanding performance and the like.

The present invention discloses a three-phase fuel cell grid-connected system, which adopts a reversible solid oxide fuel cell coordinated grid-connected microgrid structure. The entire microgrid system is based on a two-stage control structure of a DC bus and an AC bus. The DC / DC converter boosts and stabilizes the output voltage of the fuel cell to meet the grid-connected operation index. At the same time, the stable voltage output can suppress the current ripple and improve the output efficiency and service life of the fuel cell. The DC / AC inverter matches the grid-connected current and the grid voltage as well as the phase sequence and frequency consistency, thereby solving the fuel cell grid-connected problem. The invention solves the technical problem that when the fuel cell is connected to an unbalanced three-phase grid, the output power of the DC / AC inverter generates a pulsating component of the double frequency grid frequency, and under power coupling, the output current of the fuel cell has a low-frequency ripple component, which affects the output and service life of the fuel cell.

The utility model belongs to motor manufacturing technical field especially relates to a rotor structure and motor, and the rotor structure includes rotor core, and the equidistribution of multiple magnetic poles has along its circumference, and each magnetic pole is provided with at least two layers of magnetic steel slot group, and each layer of magnetic steel slot group is C type structure, and each layer of magnetic steel slot group includes two separate magnetic steel slots about direct axis symmetry distribution, and the both ends of each magnetic steel slot are closed, magnetic steel is provided with multiple sections in each magnetic steel slot. The utility model is favorable for improving the magnetic field magnetic circuit of motor, reduces the harmonic distortion rate, thereby improves electromagnetic excitation, reduces motor torque ripple, realizes better motor NVH performance.

The invention relates to the technical field of alternating current power supply control, in particular to an improved load current feedforward control method and device for an alternating current power generation system and a medium, the method is suitable for a single-phase inverter system, and the method comprises the following steps: collecting inverter output voltage and load current; applying low-pass filtering to the load current to obtain filtered load current; adding the output of a voltage loop regulator and the filtered load current after necessary compensation in amplitude and phase to generate a current instruction; and driving an inverter to output according to the current instruction to realize adjustment and feed-forward compensation of the output voltage. According to the invention, the low-frequency output impedance in the inverter can be reduced, the harmonic distortion rate of the output voltage under the nonlinear load can be reduced, and the high-frequency-band waveform of the output impedance can be improved.

The present invention belongs to the field of power electronics technology, and relates to a method and system for improving power quality by eliminating modulation of multiple zero-crossing drive vacancy areas. The method comprises the following steps: two-phase static coordinate transformation of three-phase grid voltage; calculating the phase angle relationship of grid voltage; performing two-phase rotating coordinate transformation on three-phase distorted current and three-phase output current according to the phase angle relationship; obtaining two-phase command current according to two-phase distorted current and two-phase sinusoidal current obtained by filtering the two-phase distorted current; obtaining two-phase command voltage according to DC side reference voltage and actual voltage, two-phase command current and two-phase output current; inverse coordinate transformation of two-phase command current and two-phase command voltage according to the phase angle relationship; and obtaining two-phase command voltage according to the command voltage. 、 The carrier period and the actual voltage on the DC side are used to obtain the initial modulation wave; the driving signal is generated according to the size of the final modulation wave and the positive load wave obtained by adjusting the initial modulation wave. The present invention effectively eliminates the driving vacancy area in the modulation, reduces the harmonic distortion rate, and improves the power quality.

The invention discloses a grid-connected inverter stability control method based on an improved phase-locked loop, and belongs to the technical field of new energy grid-connected control, and the method comprises the steps: firstly building a grid-connected inverter impedance model, and revealing a mechanism that the phase-locked loop introduces negative damping and reduces stability margin under a weak power grid; based on an impedance model, a composite control strategy fusing dynamic feed-forward compensation and an improved Kalman observer is designed, the former actively counteracts the negative impedance effect of a phase-locked loop, and the latter improves dynamic response through state reconstruction and advanced prediction. Finally, an improved cascade delay signal elimination phase-locked loop with a selective conduction harmonic filtering function is provided, and the improved cascade delay signal elimination phase-locked loop is deeply integrated with the control strategy and a multi-harmonic feedback link, so that high-precision phase locking and active harmonic suppression are realized. According to the method, the operation stability, the dynamic performance and the electric energy quality of the grid-connected system under the conditions of high background harmonic waves and weak power grids are remarkably improved.

An off-grid photovoltaic power generation device with energy storage comprises an inverter main circuit, an isolation driving circuit used for isolating and amplifying a sine pulse width modulation (SPWM) signal to drive a power tube, an AC voltage sampling circuit used for collecting an output voltage, a true RMS conversion circuit used for converting an AC voltage effective value into a constant DC voltage value, and a power supply circuit used for supplying power to the inverter main circuit. The filter circuit is used for filtering high-frequency carrier signals; the auxiliary power supply circuit is used for supplying power to the isolation driving circuit, the alternating-current voltage sampling circuit and the true RMS conversion circuit; the inverter main circuit is respectively connected with the isolation drive circuit, the filter circuit and the photovoltaic cell and storage battery output circuit. According to the utility model, isolation inversion from low DC voltage to high AC voltage is realized, the true RMS conversion circuit and the isolation driving circuit are adopted, the anti-interference performance of the system is enhanced, and the safety and reliability of the system and the stability of the output voltage are improved.

The invention relates to a functional outer diameter unequal-thickness magnet ring and a magnetizing method thereof, and belongs to the technical field of permanent magnet motors, the inner diameter of the unequal-thickness magnet ring is circular, the outer diameter of the unequal-thickness magnet ring is a changing curve, the thickness of the changing curve of the outer diameter at a main magnetic pole part is unchanged, and the thickness of the changing curve of the outer diameter at a transition position between adjacent main magnetic pole parts is reduced; the unequal-thickness magnetic rings are made of bonded neodymium iron boron materials. The magnetic ring is composed of a bonded neodymium iron boron magnetic ring with a functional outer diameter and a multi-pole magnetizing clamp matched with the magnetic ring, the outer diameter of the magnetic ring adopts two functional sizes, and the amplitude of cogging torque is reduced by reducing the thickness of a magnetic pole transition area and regulating and controlling harmonic components of surface magnetism of the magnetic ring. The multi-pole magnetizing iron core matched with the magnetizing clamp can magnetize the magnetic ring into a plurality of magnetic poles which are alternately distributed on the surface.

The application relates to the technical field of photovoltaic grid connection, and discloses a control method and system for photovoltaic harmonic carrier grid connection, which comprises the following steps: inverting direct current of a photovoltaic module into first alternating current based on a photovoltaic inverter; collecting a target third harmonic in a power grid and calculating target phase data of the target third harmonic; modulating a frequency of the first alternating current to be consistent with a frequency of the target third harmonic; modulating a phase of the first alternating current to be 180 degrees opposite to the target phase data; and modulating a first current amplitude of the first alternating current to be equal to a maximum current amplitude of the target third harmonic. The method can relieve the phenomenon of local high voltage of a power distribution network generated during photovoltaic grid connection and improve the stability of load equipment operation.

The present invention provides a radiation-resistant low-harmonic LED driving circuit, comprising a rectifier unit and a driving unit. The input end of the rectifier unit is used to connect an external power supply, and the output end is connected to the driving unit, and is used to obtain a direct current power supply after rectifying and filtering the external power supply, and output it to the driving unit. The driving unit is used to convert the voltage of the direct current power supply into the working voltage of the LED light source. The driving unit comprises a first chip SM2315, a first capacitor, and a second resistor. The first pin of the first chip SM2315 is connected to the output end of the rectifier unit, the second pin and the ninth pin are grounded, the third pin is connected to the first capacitor and then to the ground, the fourth pin is connected to the second resistor and then to the ground, and the eighth pin, the seventh pin, the sixth pin and the fifth pin are used to connect the LED light source. Correspondingly, an LED lamp is also provided. The LED driving circuit can effectively withstand the radiation dose within the life of the lamp, and meet the life and power distribution requirements.

The invention relates to the technical field of driving motors for electric vehicles, in particular to a modular fan-shaped rotor driving motor with non-uniform air gaps, which comprises a stator, a three-phase winding, a rotor module and a rotor fixing frame, the rotor module comprises p magnetic poles, each magnetic pole is composed of a permanent magnet and a fan-shaped iron core, the outer edge of the fan-shaped iron core is composed of two sections of arcs, the permanent magnets are embedded in the center of the fan-shaped iron core, the permanent magnets are arranged in a spoke mode, and the p permanent magnets are magnetized in the tangential direction in the anticlockwise direction. The modular fan-shaped rotor structure with the non-uniform air gaps is adopted, so that inter-pole magnetic flux leakage of the permanent magnets is reduced, the air gap flux density waveform is improved, and daily overhaul and maintenance of the motor are more convenient; the permanent magnets are magnetized in the same direction to increase the number of pole pairs of the rotor and the number of magnetic flux loops, so that the magnetic barrier effect of a traditional spoke type motor is weakened, the torque pulsation of the motor is reduced, and the working efficiency of the motor is improved.