37results about How to "Eliminate higher harmonics" patented technology

The invention relates to a battery energy storage system based power conversion system and a control method thereof. The power conversion system comprises a battery energy storage system, a bidirectional DC/DC (direct-current) converter, a grid-side current transformer, a filter circuit and an isolated voltage transformer. The battery energy storage system is in parallel connection with a direct-current bus of the grid-side current transformer through the bidirectional DC/DC converter; the grid-side current transformer, the filter circuit and the isolated voltage transformer are connected in sequence; and the isolated voltage transformer accesses to a power grid. The control method includes sequentially monitoring the battery energy storage system, the bidirectional DC/DC converter, the grid-side current transformer, the filter circuit and the isolated voltage transformer by a control circuit. Since the battery energy storage system utilizes battery cells connected in series and is in parallel connection with the common direct-current bus through the bidirectional DC/DC converter, circulation among battery packs is avoided, and capacity expansion of the system is facilitated. Further, by the aid of the monitoring control strategy for SOC (super capacitor state of charge) of the battery energy storage system and battery end voltage, excessive charge or discharge state of the battery energy storage system is avoided, service lives of the battery packs are prolonged, and comprehensive service cost is lowered.

The invention relates to a two-stage photovoltaic grid-connected control system based on the combination of pole allocation and repetitive control, which can invert the direct current output by a photovoltaic cell into alternating current well and transmit the alternating current to a power system, so that the harmonic wave content is low, the power supply quality is good, the utilization ratio of a system is high, the stability of the system can be improved to a certain extent and the properties of the whole photovoltaic system are improved. The two-stage photovoltaic grid-connected control system based on the combination of pole allocation and repetitive control has the advantages that: (1) due to the adoption of numerical control, the antijamming capacity is high and the system can achieve high precision and stability; (2) the system has clear assignment, obvious control effect, reliability and high robustness, wherein a preceding-stage Boost converter can realize maximum power tracking; and a last-stage inverter achieves direct current side voltage stabilization and grid-connected inversion; and (3) a control algorithm is advanced, wherein a dead zone effect of the inverter and the harmonic wave caused by partial non-linear loads are avoided by a repetitive control technique; and precise control is realized through the state feedback-based pole allocation.

The invention discloses a winding-type linear brushless doubly-fed generator, and proposes a unit motor according to a unit motor concept, wherein the total number of pole-pairs of a stator power winding and a control winding of the unit motor is N times. Meanwhile, a rotor winding employs a mode of symmetric distribution like a sine rule according to the principle of tooth harmonic, thereby reducing coils of different phases of a power winding P1 and a control winding P2. The rotor winding can achieve the coupling of a control winding and another winding well, and the air-gap magnetic density harmonic is lower. The generator can enable a magnetic field with a lower moving speed to be modulated into a high-speed magnetic field, and effectively improves the power density. The control winding is placed at a stator side, and a sliding ring and a brush are removed. The generator is low in motor failure rate, is long in service life, eliminates the higher harmonic of a magnetomotive force of a rotor to the maximum degree through the adjustment of the span and turns of a rotor coil, achieves the higher winding coefficients of the pole pairs of power windings P1 and P2, and achieves the high efficiency and energy saving.

The invention relates to a skewed rotor core which comprises a rotating shaft and a skewed rotor core, wherein the skewed core consists of two or more than two one-way skewed cores; the two adjacent one-way skewed cores have different inclined directions; an inflection point is formed at the intersection of adjacent two skewed slots; and the one-way skewed cores is formed by laminating rotor sheets. By adoption of a connecting key groove through which the one-way skewed rotor core in each skewed section is laminated and correspondingly the one-way skewed rotor core in a skewed section is generally processed, each rotor sheet can be directly punched on a common punch press, so that the processing period and cost are greatly reduced. The invention relates to a motor comprising the skewed rotor core, and a method for manufacturing the skewed rotor core.

A magnetic sensor comprises magnetoresistor thin films used in view of improvement of identification accuracy of operation of the magnetic sensor so as to prevent degradation of the degree of freedom of arrangement attributed to the narrow intervals between the magnetoresistor thin films. The number of magnetoresistive elements for canceling the harmonics can be increased to an extent that the production of the magnetic sensor does not became difficult while flexibly adjusting the intervals between magnetoresistive elements. The thermal characteristics are uniformed and the identification accuracy is improved. The magnetic sensor has magnetoresistance pattern where magnetoresistor thin films are formed on a substrate, and the magnetoresistance pattern is composed of A-phase and B-phase magnetoresistance patterns which output two signals having phases which are different by 90 DEG. The magnetic sensor is characterized in that the magnetoresistance pattern is formed by combining two substrates.

The invention relates to a wind power generation simulation system based on a brushless synchronous generator. In the technical scheme, a frequency converter 2 is connected with a power grid 1 and is used for controlling an electric motor 3 of a simulation blade, a brushless synchronous wind power generator is connected behind the electric motor 3, the current from the generator flows to the power grid 1 through a full-power rectification inverter circuit 5 based on AFE, and the whole system forms a closed-loop circuit. A control system 6 is used for controlling the frequency converter 2 and the full-power rectification inverter circuit 5 so as to complete the system control. The simulation system adopts the brushless synchronous wind power generator without slip ring or electric brush, thereby improving the system reliability and safety. Simultaneously, due to the full-power rectification inverter circuit based on the AFE, the simulation system not only can eliminate the higher-order harmonics and improve the power factor, but also can not be affected by fluctuations of the power grid, thereby achieving good dynamic properties.

The invention relates to a three-phase high-frequency inversion high-voltage rectification electrostatic dust collection integrated power supply. The power supply is formed by integrating a three-phase power-frequency low-voltage rectifier SZ, a filter CL, a three-phase high-frequency low-voltage inverter PF, a three-phase high-frequency low-voltage input/multi-phase high-frequency high-voltage output transformer PB and a multi-phase high-frequency high-voltage rectifier PZ in a sequentially connected mode. By the adoption of the three-phase high-frequency low-voltage inversion structure PF, efficiency and reliability of the high-frequency inverter can be improved. By the adoption of the multi-phase boosting transformer structure PD, efficiency and safety of the high-frequency transformer can be improved. By the adoption of the multi-phase rectification structure PZ, high-frequency rectifier efficiency can be improved, and higher harmonic can be lowered. The three-phase high-frequency inversion high-voltage rectification electrostatic dust collection integrated power supply has the advantages of being high in power, efficiency and reliability, low in harmonic, material consumption and energy consumption, and the like.

The invention discloses a power amplifier and an implementation method thereof. The power amplifier comprises a main circuit, a first feedback circuit and a second feedback circuit; the main circuit comprises a first input matching circuit, a first output matching circuit and a power amplifier chip biased on the B class; the first feedback circuit comprises a second input matching circuit, a second output matching circuit and a three-way frequency divider; the second feedback circuit comprises a third input matching circuit, a third output matching circuit and a two-way frequency divider. According to the power amplifier and the implementation method thereof, the input end and the output end of the power amplifier chip biased on the B class are connected with the two-way frequency divider and the three-way frequency divider respectively to form the two regenerative feedback circuits, and therefore second harmonics and third harmonics in a power amplifier chip output signal can pass through the frequency dividers respectively to be converted into fundamental harmonics and then fed back to the input end of the chip; higher harmonics in the output signal are eliminated, the high linearity is improved, and the power amplifier biased on the B class enables the circuits to have higher efficiency.

The invention discloses a Coriolis mass flowmeter signal processing method based on a frequency mixing algorithm. After adjustment and analog-digital conversion are carried out Coriolis mass flowmeter signals, sampled data are processed in a unitization mode and are mapped to the range from 0 to 1, then frequency mixing calculation is carried out, low-frequency interference, ultraharmonics and noise in the signals are filtered away, the phase difference of two paths of signals is solved, vibration frenqeuncy is caught at the same time, signal frequency and the information of the phase difference of a Coriolis mass flowmeter are obtained, and therefore the mass flow rate and density of fluid medium flowing through a vibration tube are solved. By means of the Coriolis mass flowmeter signal processing method based on the frequency mixing algorithm, the ultraharmonics and noise in the signals are eliminated, the calculation accuracy is high, calculation speed is high, and the frequency range of applicable sensors is wider. The Coriolis mass flowmeter signal processing method based on the frequency mixing algorithm is not only applicable to an ordinary tube type sensor, but also a slightly bent type sensor.

The invention provides a grid-connected inverter control method and system. The method comprises the following steps: detecting and obtaining a busbar voltage; carrying out harmonic eliminating processing on the busbar voltage to obtain a detection voltage; calculating a voltage difference between the detection voltage and a preset standard voltage; generating a standard current according to the voltage difference; obtaining the current at an output end of the inverter, and carrying out filtering processing on the obtained current to obtain a detection current; calculating a current difference between the detection current and the standard current according to the detection current and the standard current; and generating a control signal according to the current difference, wherein the control signal is used for controlling the inverter to generate an output current. The grid-connected inverter control method and system reduce the influence on grid-connected current quality caused by busbar voltage harmonics.

The invention relates to a low power three phase motor. Wherein, the stator has a star winding and a triangle winding; the phase bands of said two windings are alternatively distributed while the electrical angle distance of central space of nearby phase bands is ªð/6; the invention is characterized in that: the stator has 4 electrodes and 24 grooves while it is consequent pole single-phase winding, the edge of star winding and the edge of triangle winding individually takes up 12 grooves while said two windings are alternatively distributed along the grooves; the number of turn of triangle winding is the 1.73 times of the number of turn of star winding while its wire diameter is the 0.76 times of the wire diameter of star winding; according to the phase sequence, the initial terminal of each phase of star winding is connected to the power source and every linear terminal of triangle winding is connected to the end terminal of relative phase of star winding or the initial terminal of each phase of star winding and every linear terminal of triangle winding are connected to the power source while the end terminals of each phase of star winding are connected each other. Compared to the present technique, the invention can improve the coefficient of winding and weaken higher harmonic to improve the property, reduce the cost, improve the start property and reduce the electromagnetic vibration noise.

The invention discloses a power supply circuit and application thereof, which utilizes the electromagnetic induction relationship between conductive winding coils on a magnetic conductive iron core to generate a multi-phase alternating current power supply from a given alternating current power supply, and the multi-phase alternating current power supply passes through a multi-phase bridge rectifier circuit and is directly used as a direct current voltage source with a very small ripple factor without capacitor filtering. Direct-current voltage and current are output, so that higher harmonics caused by capacitor filtering are fundamentally eliminated; and meanwhile, the current input from the power grid by the multi-phase bridge rectifier circuit is sine wave or step wave very close to the sine wave, so that higher harmonics generated at the alternating current side can be reduced to the minimum without power factor correction.

The present invention discloses a current sampling circuit. The circuit comprises an RC filtering circuit and an amplification circuit; the input end of the RC filtering circuit receives current sampling signals and are used for filtering the current sampling signals; and the input end of the amplification circuit is connected with the output end of the RC filtering circuit and is used for amplifying the current sampling signals filtered by the RC filtering circuit and transmitting the amplified current sampling signals to a sampler. According to the current sampling circuit of the invention,the RC filtering circuit and the amplification circuit are adopted, and therefore, the problem that a current sampling circuit in the prior art is greatly affected by higher harmonics can be solved.

The invention relates to a power-saving winding using a combined ferrite iron core for saving power in the electricity grid. In the power-saving winding, a Z-shaped winding form is adopted to wind three coils on a square iron core with a middle line, i.e. two ends of the first coil are winded on the left pillar of the iron core, and the middle section is winded on the middle pillar of the iron core; two ends of the second coil are winded on the middle pillar of the iron core, and the middle section is winded on the right pillar of the iron core; two ends of the third coil are winded on the right pillar of the iron core, and the middle section is winded on the left pillar of the iron core. The iron core of the winding is formed in such a way that five rectangular ferrite iron cores are adhered or tied together. The winding made by the winding way has high magnetic flux density, large capacity and small volume, and can correct bias wave, reduce neutral current, reach the effect of removing upper harmonics and adjusting three-phase balance, can save power and improve service life of the electric facilities.

The invention discloses an energy preine saving purifying AC stabilizied-voltage power, it includes: power switch, panel, power light, output power line connection end, filter and transformer circuit, photoelectric inspection circuit, sampling and comparing circuit, controlling circuit, overvoltage crowbar, compensating and optimizing circuit, when it is used in two-phase circuit, the compensating and optimizing circuit is composed of two equipments, each one has two magnetic sheet capacitance, a setting ruler capacitance, an inductance, an unilateralism controllable silicon, three resistances, an indicator light and a voltage dependent resistor, the two compensating and optimizing circuits have symmetrical style and different value, and are formed a strong against weak complementary circuit. The compensating and optimizing circuits can achieve the intention of stabilizing voltage, saving energy by absorbing and releasing energy.

The invention relates to an asymmetric regular mode-mixing filter, comprising a main body and a cover plate, wherein first to fifth circular cavities are arranged on one surface of the main body and are internally and uniformly provided with harmonic oscillators; an input end and an output end are arranged on the wall of the main body and are respectively connected with the harmonic oscillators in the first circular cavity and the fifth circular cavity; the first circular cavity, the second circular cavity and the third circular cavity are arranged at a first straight line, the fifth circular cavity and the fourth circular cavity are arranged at a second straight line, the first straight line is parallel to the second straight line, the fourth circular cavity, the third circular cavity and the second circular cavity are arranged in shape of triangle, and the fifth circular cavity, the second circular cavity and the first circular cavity are arranged in shape of the triangle; and radial connection lines among the first to fifth circular cavities are provided with coupling windows. The asymmetric regular mode-mixing filter disclosed by the invention has the characteristics that the harmonic oscillators in the first, second, fourth and fifth circular cavities are metal coaxial harmonic oscillators, and the harmonic oscillator in the third circular cavity is a medium loading harmonic oscillator. The asymmetric regular mode-mixing filter disclosed by the invention has the advantages of wide use range and low manufacturing cost, and is suitable for wireless communication base station.

The invention relates to a single-phase capacity motor. Wherein, its stator has a three phase winding, two input terminals connected to the two electrodes of single-phase power source and the second input terminal via the capacitor connected to one electrode of said single-phase power source. And the invention is characterized in that: said three phase winding comprises a star winding with a star connection to said three input terminals and a triangle winding with a triangle connection to said three input terminals; the phase band of said star wind and the phase band of triangle winding are alternatively distributed in the stator groove while the electrical angle distance of central space between nearby phase band is ªð/6; And the current time phase angle difference of said nearby phase bands has the same sign with the electrical angel distance of central space of phase band. Compared to the present technique, the invention can improve the coefficient of winding and weaken higher harmonic to improve the property, reduce the cost, improve the start property and reduce the electromagnetic vibration noise.

The invention discloses a superposed boosting type power supply system for an electrostatic precipitation device based on an inductance filter circuit. The superposed boosting type power supply systemfor the electrostatic precipitation device based on the inductance filter circuit mainly comprises an adjusting chip U, an amplifier P1, the inductance filter circuit, a triode VT1, a triode VT2, a triode VT3, an amplifier P2, a field-effect transistor, a voltage stabilizing diode D4, a diode D6, a polar capacitor C4 and the like; and the positive pole of the polar capacitor C4 is connected witha source electrode of the field-effect transistor while the negative pole of the polar capacitor C4 is connected with an N pole of the diode D6 and then is grounded. Higher harmonics generated in voltage due to electromagnetic interference are eliminated, so that the voltage can be stable; voltage fluctuation can be adjusted to enable the voltage to be stable; moreover, the voltage can be boostedby two-time superposition on the voltage, so that stability of output voltage is ensured; and the adsorption effect of a permanent charged filter element of an air purifier of a high-voltage electrostatic precipitation device can be improved effectively.

The invention discloses a voltage-dividing adjustable boost power supply system for a high-voltage electrostatic dust collection device, which mainly consists of an adjusting chip U2, an inductance filter circuit, a diode rectifier U1, a field effect transistor MOS, a triode VT, a voltage stabilizing diode D2, and a diode D4 , the inductance L1, and the polarity capacitor C5 whose anode is connected to the source of the field effect transistor MOS, whose cathode is connected to the N pole of the diode D4, and then grounded. The present invention can eliminate the high-order harmonics generated by electromagnetic interference in the voltage to make the voltage more stable, and can adjust the voltage fluctuation to make the voltage more stable, and the present invention can superimpose the voltage twice Boosting is realized, thereby ensuring the stability of the output voltage of the present invention, and effectively improving the adsorption effect of the permanently charged filter element of the air purifier of the high-voltage electrostatic dust collecting device.

The invention provides an electromagnetic descaling device power circuit, and the circuit comprises a direct current power supply, an inverter, a resonance network, a feedback network, a driver and a driving network, wherein two input ends of the inverter are respectively connected with the positive electrode and the negative electrode of the direct current power supply, and the inverter comprises a plurality of driving transistors; the resonance network is connected in parallel with the output end of the inverter and the negative electrode of the power supply, or the resonance network is connected in series between the two output ends of the inverter; the driver, the driving network and the gate electrode of the driving transistor are connected in series along the passing sequence of the PWM signal; a feedback network is connected between the drain to the gate of each drive transistor. The efficiency of the descaling device can be greatly improved.

The invention discloses a control device for improving the output voltage distortion degree of a frequency converter. The device comprises a low-pass filter disposed between the output end of the frequency converter and a load, and also comprises a control filtering mechanism disposed between the low-pass filter and the load, wherein the control filtering mechanism comprises a PLC, a contactor K1,and capacitors U4-U6, wherein the contactor K1 is electrically connected with the PLC, and the capacitors U4-U6 are respectively connected with the contactor K1. By judging the output frequency of the frequency converter and controlling the switching-on and switching-off of the filter capacitors on line, filtering parameters are dynamically adjusted, the output voltage distortion degree of the frequency converter at the frequency of 50 Hz to 100 Hz is improved, higher harmonics of the frequency band are eliminated, and then the filtering effect is improved.

The invention discloses a broadband filtering compensation transformer, wherein each of three phases of the transformer adopts two layers of foil windings which are insulated from each other, the two layers of foil windings which are insulated from each other are also two polar plates of a capacitor, voltage difference is generated between the two windings through a wiring mode, and a broadband inductance and capacitance (LC) filtering absorption circuit is formed. The broadband filtering compensation transformer is reasonable in design, the broadband LC filtering absorption circuit is formed, the higher harmonic of a power grid is effectively eliminated, and the reactive power of a network is compensated.