1134results about How to "Harmonic reduction" patented technology

This invention relates to solar volt flexible switch reverser, which belongs to solar volt power generation technique field, which exerts direct voltage of the solar energy board into input capacitor two ends, wherein, input capacity end is connected to second induction end; other end of second induction is connected to integration electrode and first capacitor end; the first capacitor other end is connected to the encode end of third, second tubes and emission electrode of thirst control switch.

A single phase power supply module for electric arc welders and plasma arc cutters comprising: a single phase input stage; positive and negative output terminals; a full wave rectifier connected to the input stage for rectifying the single phase voltage at the input stage; a buck converter type power factor correcting circuit for controlling current flow from the input stage to the rectifier, which buck converter has an output capacitor regulated to an intermediate voltage in the range of 100-150 volts; and, a high speed DC to DC converter having an internal transformer coupling applying voltage across the output terminals and means for regulating the applied voltage to an output voltage in the range of 0-113 volts. The module is universal and several can be connected in parallel, in series or to switch networks to construct several welders or cutters.

Disclosed is an apparatus and method for operating a microwave amplifier with improved efficiency and reduced harmonic emissions. The disclosed amplifier includes a variable rail voltage supply and a variable input drive stage. A controller continually monitors the amplifier output and adjusts the rail voltage and input drive signal to achieve high efficiency and low harmonic emissions. The amplifier may include a dynamic bias controller configured to operate the gain elements outside the linear region. Efficiencies of over 70% may be achieved by the disclosed amplifier.

An excitation circuit for a flux switching motor. The circuit includes a low-value film capacitor across the DC side of a bridge rectifier. A plurality of electronic switches are arranged in an H-bridge configuration for switching current flow through an armature winding of the motor in accordance with a PWM control scheme and single-pulse control scheme controlled by a microcontroller. A start-up diode is placed across the field winding of the motor and is electronically switched out of the circuit after a startup phase of the motor has completed. The circuit implements armature energy recirculation through the field winding during startup to promote more uniform and quicker startup of the motor. The use of a film capacitor improves the power factor of the circuit, helps to eliminate the introduction of harmonics into the AC voltage source, and helps in mitigating EMI. Reverse commutation is used to bring the motor to a quick stop when it is powered off.

A permanent magnet synchronous machine with improved torque and power characteristics. A circumferential-oriented rotor assembly is provided with alternating permanent magnets and magnetic pole pieces. In order to reduce the amount of leakage flux in the rotor and increase the effective length of the permanent magnet, a trapezoidal or otherwise tapered permanent magnet structure is used. By alternating trapezoidal permanent magnet, and magnetic pole pieces, a higher intensity magnetic field is created in the air gap utilizing the same radial space in the motor without altering the weight or volume of the motor compared to conventional machines.

The invention provides a network voltage disturbance generating device, which comprises a three-phase bridge type PWM (Pulse Width Modulation) rectifier and a three-H-bridge three-phase four-wire-system PWM inverter, wherein the alternating current side of the rectifier is connected with an electric network through an L type filter; the direct current side of the rectifier is connected in series with the direct current side of the three-H-bridge three-phase four-wire-system PWM inverter; an LC filter is connected to the alternating current side of the three-H-bridge three-phase four-wire-system PWM inverter; the output end of the LC filter is connected with an isolation transformer; and the secondary side of the isolation transformer is connected with a load. The invention further provides a control method suitable for the device. Due to the adoption of the device provided by the invention, the simulation of a network voltage amplitude, frequency disturbance and an electric network harmonic phenomenon can be realized, bilateral flow of energy can be realized, and active energy transmitted by tested solar-powered grid-connected equipment is fed back to the electric network; and the control method is easy and convenient to implement, and a target reference value can be accurately tracked; and moreover, quick response and small steady-state errors are realized, so that electric network disturbance can be simulated accurately.

The invention discloses a direct current de-icing device based on a full-bridge modular multilevel converter. The full-bridge modular multilevel converter has a three-phase bridge structure, each phase of the converter comprises an upper bridge arm and a lower bridge arm, the upper and lower bridge arms which are respectively formed by serially connecting N full-bridge power modules end to end, and the full-bridge power modules form a chain type multilevel structure, the front ends of the first power modules of the upper bridge arms of all phases are connected to form the positive pole of a public direct current bus; the tail ends of the Nth power modules of all lower bridge arms of all phases are connected to form the negative pole of the public direct current bus; the tail ends of the Nth power modules of all upper bridge arms are connected with the front ends of the first power modules of the respective lower bridge arms of the phases by smoothing reactors; and the center of the electric reactor serves as the alternating current bus of the phase. The device has high high-voltage direct current output capacity and the direct current voltage of the device can be regulated continuously from zero; on the other hand, the fully compatible chain type scalable vector graphics (SVG) topology can realize quick dynamic reactive regulation; and the device has the combined functions of direct current de-icing and alternating current dynamic reactive compensation.

The invention relates to a current control method for a flexible DC transmission convertor and a device thereof, which pertains to the technical field of power transmission in wind power generation. The current control of the invention adopts a hysteresis loop comparator with the adjustable width of a hysteresis loop; the current bias is compared with the width of the hysteresis loop; when the current bias exceeds the width of the hysteresis loop, the hysteresis loop comparator outputs switching signals to change the switching tube state of the bridge circuit of the convertor and reduce the current bias so as to achieve the purpose of current tracing control; meanwhile, the closed loop control of switching signal frequency is brought in by the hysteresis loop comparator; the phase and the period of the switching signal are controlled to be equal to the phase and the period of a fixed clock signal by the dynamic regulation to the width of the hysteresis loop, thus causing the frequency of the switching signal to be a fixed value. The method and the device promote the dynamic response speed and precision of the current tracing control of the flexible wind power DC transmission convertor on the sea, meanwhile, the switching frequency of the power tube of the convertor is kept to be fixed, switching stress and switching lose are reduced and the transmission efficiency is improved.

The invention relates to a voltage conversion device in the electronic power system in order to simplify the loop structure, save switch devices and solve the issues of bidirectional flow of the power as well as the equal flows in the low voltage stages. The device includes 1-4 phases. Each phase is independent with the identifical structure composed of the high voltage stage, the isolation stage and the low voltage stage. The high voltage stage includes 2-30 identical power conversion modules in serial. The isolation stage includes the part of the modulation/demodulation in high frequncies etc. The low voltage stage includes the power conversion module. Comparing with the foreign scheme, the number of the devices is reduced one-third, and the cost also is reduced.

A power amplifier module for amplifying radio frequency signals includes first, second, third and fourth corner ground pads positioned at each corner of the power amplifier module; a radio frequency input pad positioned between the first and second corner ground pads; a radio frequency output pad positioned between the third and fourth corner ground pads; and a power amplifier circuit centrally positioned on the power amplifier module, the power amplifier having an input coupled to the radio frequency input pad and an output coupled to the radio frequency output pad.

An inverter controlling method is applied in a system comprising a single-phase rectification circuitry and three-phase inverter. The method determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry for allowing an output voltage of the single-phase rectification circuitry to pulsate at twice frequency with respect to a power frequency; controls the three-phase inverter for supplying output voltages or output currents from the three-phase inverter to a motor; and suppresses a current flowing into the capacitor from a power source via the single-phase rectification circuitry.

The invention belongs to the field of wind generator power conversion device control, and relates to a constant-frequency direct power control method for a PWM converter under the condition of power grid voltage imbalance. The method comprises the following steps of: determining a sampling frequency; acquiring a three-phase power grid voltage, a three-phase power grid current and a direct-current side voltage, and calculating resultant vectors E and I of the power grid voltage and the power grid current in a three-phase static coordinate system respectively; calculating positive and negative sequence components of the power grid voltage and the power grid current; calculating an instantaneous power and an instantaneous power error; calculating a converter reference voltage, and performing inverse transformation on the converter reference voltage; performing amplitude limit on the converter reference voltage to obtain the resultant vector of the converter reference voltage after the amplitude limit; and modulating the resultant vector of the converter reference voltage after a space vector modulation algorithm is adopted for amplitude limit, and outputting the converter voltage. The method can inhibit the active power fluctuation of the system more effectively and greatly reduce the harmonic wave of the alternating-current side current; and the output converter voltage switch frequency is constant, so the output filter parameter design is simpler.

A renewable energy-based hybrid bi-directionally interactive DC traction power supply system includes two traction substations. Each substation includes transformers, rectifiers, bidirectional AC-DC converters, a DC bus, a catenary, a steel rail and a section post. A DC bus between two adjacent traction substations is provided with a DC renewable energy system constructed by an electric vehicle charging-discharging system, a distributed generation and more than one low voltage DC microgrid. The DC renewable energy system is connected to the DC bus between two adjacent traction substations through a high voltage DC bus, thus a DC circular microgrid being formed in a power supply section post. The electric vehicle charging-discharging system is formed by more than one bidirectional DC-DC charging-discharging equipments which are intended for in connection with the power batteries of the electric vehicle. The renewable energy-based hybrid bi-directionally interactive DC traction power supply system of the invention realizes effective usage of distributed generation and recycling of electric locomotive braking energy, reducing DC voltage fluctuation, thus improving reliability of the DC traction power supply system.

The invention provides a magnetic field modulating type concentric magnetic gear transmission device in a Halbach magnet structure, which comprises a shell, an outer rotor and an inner rotor, whereinthe outer rotor and the inner rotor are installed in an inner cavity of the shell and are in a cantilever type; the inner rotor comprises an inner rotor iron core and a permanent magnet, which are installed on an output shaft of the inner rotor; the outer rotor comprises an outer rotor iron core and a permanent magnet, which are installed on an output shaft of the outer rotor; a magnetic modulation ring is arranged between the permanent magnet of the inner rotor and the permanent magnet of the outer rotor; and the magnetic modulation ring comprises an iron core block and is fixed on an end plate of the shell. The magnetic gear transmission device comprises two layers of air gaps, wherein an inner-layer air gap is formed between the inner rotor and the magnetic modulation ring, and an outer-layer air gap is formed between the outer rotor and the magnetic modulation ring. The magnet structure uses a Halbach array to replace the conventional radial structure, thereby improving the magnetic density distribution of the air gaps of the magnetic gear transmission device. Because the magnetic density of the air gaps approaches to sinusoidal distribution, the detent torque of the magnetic gear transmission device in the structure is greatly reduced, thereby decreasing the vibration and noise of the magnetic gear transmission device and improving the running efficiency.

A permanent-magnet synchronous machine includes a stator that has slots and a rotor that has permanent magnets which form magnet poles. The permanent magnets are shell magnets having two curved surfaces. Each shell magnet covers a predetermined part of a magnet pole. The external radius of the shell magnets is less than 0.6 times the radius of the stator bore. Each shell magnet has a quasi-radial magnetic preferred direction that is directed substantially perpendicular to its outer surface.

One high-frequency switch Qm supplied with transmit and receive signals to ON, and another high-frequency switch Qn supplied with a signal of another system to OFF are controlled. In the other high-frequency switch Qn, to set V-I characteristics of near-I/O gate resistances Rg1n-Rg3n of a near-I/O FET Qn1 near to a common input/output terminal I/O connected with an antenna are set to be higher in linearity than V-I characteristics of middle-portion gate resistances Rg3n and Rg4n of middle-portion FETs Qn3 and Qn4. Thus, even in case that an uneven RF leak signal is supplied to near-I/O gate resistances Rg1n-Rg3n, and middle-portion gate resistances Rg3n and Rg4n, the distortion of current flowing through the near-I/O gate resistances Rg1n-Rg3n near to the input/output terminal I/O can be reduced.

The invention relates to a phase shift soft switch high frequency isolation photovoltaic grid-connected inverter which comprises a main circuit, a DSP control circuit, an ARM control circuit, and an auxiliary switch power supply circuit. The invention firstly provides a full digitalization control photovoltaic grid-connected generating system, wherein a high frequency full bridge phase shift circuit combined with a high and low frequency full bridge inverter circuit is main circuit structure, and high speed embedded digital signal processor DSPTMS320F2808 is a core. Maximal power point tracking of solar cell panel output power and isolation of photovoltaic direct current and electrical network alternating current are realized, software realizes phase-locked loop control, perfect grid-connected and islanding protection functions are provided, and the whole system can operate safely and reliably.

A solar energy grid-connected inverter control system based on LCL filtration comprises a photovoltaic array, an electromagnetic interference filter, namely an EMI filter, a power module, an LCL filter, an isolation transformator TB1, a sample circuit, a filter circuit and a controller which includes a maximum capacity tracking MPPT unit. MPPT adopts an intelligent algorithm based on a hybrid algorithm of a simulated annealing method and a genetic algorithm. The hybrid optimization algorithm takes the operation process of the genetic algorithm as the main process and also combines a simulated annealing mechanism that is used for further adjusting optimized instruction data. The control system has the advantages of good stability, strong performance and high efficiency and reliability.

The invention discloses low-noise feature oriented silicon steel which comprises a silicon steel base plate and an insulating coating, wherein the silicon steel base plate is coated with the insulating costing. In addition, the tension range of the insulating coating ranges from 6 MPa to 8 MPa. The content of Cu in the silicon steel base plate satisfies the inequation that 0.1%<=Cu<=0.5%, the content of S in the silicon steel base plate satisfies the inequation that 0.01%<=S<=0.05%, and the atomic ratio of Cu/S satisfies the inequation that 5<=Cu/S<=10. The invention further discloses a manufacturing method for the low-noise feature oriented silicon steel. The method sequentially includes the steps of firstly, smelting and casting to form a plate blank, secondly, heating, thirdly, normalization, fourthly, cold rolling, fifthly, decarbonization annealing, sixthly, finished product annealing, and seventhly, thermal drawing annealing, wherein the surface of the silicon steel base plate is coated with the insulating costing, and the coating quantity is adjusted so that the tension range of the insulating coating can range from 6 MPa to 8 MPa. The low-noise feature oriented silicon steel is small in magnetostriction, vibration generated by an iron core made of the silicon steel is small, and therefore the overall noise level of a transformer is reduced.