37results about How to "Improve harmonic performance" patented technology

A heating apparatus using an electromagnetic wave is disclosed, by which cut-of performance of an electromagnetic wave is enhanced by increasing an electromagnetic wave absorption bandwidth having cut-off performance below −70 dB. The present invention includes a door provided to an open front side of a body to be opened / closed and a choke filter having a panel type choke part arranged by at least one row each along an edge of the door and a filter part arranged by at least one row each along an edge of the choke part and having a plurality of slots, wherein a prescribed choke part is provided to a most inner side among rows of the choke and filter part.

The invention discloses a multi-parallel inverter motor speed regulating system and a control method of the multi-parallel inverter motor speed regulating system. The system is formed by connecting multiple inverter modules in parallel. The direct current sides of multiple inverter sub modules are directly connected with a direct current power supply with a direct current bus capacitor in parallel. The alternating current sides of the multiple inverter sub modules are connected with multiple sets of smoothing reactors respectively in series and then directly connected in parallel to drive an alternating current motor. By the adoption of the structure, modularization expansion of the motor speed regulating system is easily conducted, and the fault-tolerance performance of the motor speed regulating system is enhanced. By means of a random SVPWM method based on carrier phase shifting, switching frequency of parallel inverters is equivalently improved, switching subharmonic energy within narrow frequency bands is equalized, the harmonic performance of output currents of the parallel inverters is improved, and electromagnetic interference resistance of the motor speed regulating system is enhanced. By the adoption of a space vector synthetic technology for dynamically allocating SVPWM zero vectors, zero-sequence circulating currents between the parallel inverter modules are effectively eliminated, and normal operation of the system is guaranteed.

The invention discloses a repetitive-control-based method for controlling a compensation current of a DSTATCOM (Distribution Static Synchronous Compensator). The method comprises the following steps of: (1) acquiring a grid voltage, a load current and the compensation current; (2) extracting current commands from the load current; and (3) carrying out repetitive control and PI (Proportional-Integral) control according to the current commands, and then, outputting voltage commands to the DSTATCOM. According to the repetitive-control-based method for controlling the compensation current of the DSTATCOM, the no-static-error tracking of the low-order harmonics, comprising fundamental harmonics, of the DSTATCOM can be achieved, the compensation accuracy of the DSTATCOM is improved, the compensation bandwidth of the DSTATCOM is increased, and the compensation capability and accuracy of the DSTATCOM with unbalanced loads are improved, so that the DSTATCOM can have harmonic compensation and suppression capabilities, the use of passive filters at the outlet side of the DSTATCOM is reduced, the harmonic performance of the compensation current of the DSTATCOM is improved, the harmonic output is reduced, and the pollution to a power grid is reduced.

The invention relates to the technical field of communications, and particularly relates to a circuit structure for improving the harmonic performance of a radio frequency power amplifier. The circuit structure comprises a radio-frequency power amplifier tube, a secondary harmonic suppression network, a triple harmonic suppression network, a higher harmonic suppression network, a first matching inductance, a second matching inductance and a blocking capacitor, wherein the first matching inductance, the second matching inductance, the triple harmonic suppression network and the higher harmonic suppression network form a low-pass output matching network of the power amplifier and the low-pass output matching network is connected to a collector of the power amplifier tube; the secondary harmonic suppression network is connected to the collector of the power amplifier tube, and is independent from the output matching network, the suppression frequency can be regulated, the triple harmonic suppression network and the higher harmonic suppression network are included in the output matching network, and the higher harmonic suppression frequency can be regulated. According to the above content, the circuit structure provided by the invention is simple in structure and strong in flexibility; the harmonic component generated by the radio frequency power amplifier is effectively suppressed and the performance of the power amplifier is improved.

The invention discloses a five-phase inverter random SVPWM modulation method, and belongs to the technical field of multi-phase inverter drive control. In every sampling cycle, the sampling cycle is kept constant, a PWM pulse is delayed randomly, to achieve random change of a switch cycle, at the same time, two vector action time obtained through an NFV-SVPWM algorithm are randomly allocated, and double-random of switch frequency and zero vector action time is achieved. According to the five-phase random SVPWM modulation method, on the condition of not influencing low frequency-band harmonic performance, the amplitude of higher harmonic is drastically lowered, harmonic originally concentrated on the switch frequency and around the integral multiple switch frequency is dispersed into a wider frequency spectrum range, thus a more consecutive and even frequency spectrum is obtained, electromagnetic interference and high frequency noise are effectively inhibited, and the electromagnetic compatibility of the system is improved.

The invention discloses a power generation energy storage device based on cascade H bridge and multiport DC converter. The power generation energy storage device comprises a first full-bridge converter connected with a power generation module, a second full-bridge converter connected with an energy storage module, a third full-bridge converter connected with a multi-winding transformer, and a H bridge converter connected with an electric grid through a filter inductor. By a power generation / energy storage hybrid device, irregular new energy generated power becomes relatively smooth, and an electric grid current is limited when electric grid voltage drops. A multiport full-bridge isolated DC / DC converter can realize flexible match between the power generation module and the energy storage module with different output voltage grades, meanwhile, soft switching is realized by transformer leakage inductance and switching element stray capacitance, relatively high efficiency and electric isolation are realized, and cost is lowered. The cascade H bridge inverter is used on the electric grid side, thus, multi-level output voltage is obtained, and electromagnetic compatibility and grid connection harmonic performance are improved.

The embodiment of the invention discloses a small dielectric dual-mode filter without a shell, and belongs to the technical field of communication. The filter comprises n resonant cavities connected in series through a metal rod, wherein a metal sheet is arranged between every two adjacent resonant cavities, the first resonant cavity and the last resonant cavity in the n resonant cavities are metal resonant cavities, the remaining n-2 resonant cavities in the n resonant cavities are dielectric dual-mode resonant cavities, the dielectric dual-mode resonant cavities are of a symmetrical polygonal structure, metallization of the surfaces of the dielectric dual-mode resonant cavities is achieved, and the n resonant cavities are coupled through coupling windows on the metal sheets. According tothe filter provided by the embodiment of the invention, a metal shell does not need to be arranged outside the dielectric dual-mode resonant cavity, so that the filter has the advantages of being compact in size, small in loss, large in power capacity, high in out-of-band rejection and good in harmonic performance so as to effectively improve the anti-interference capacity and the frequency spectrum utilization rate of a 5G communication system, reduce the power consumption of the 5G communication system and improve the coverage range of the 5G communication system.

The invention discloses an indirect matrix transformation type multi-phase multi-level permanent magnet motor system. The indirect matrix transformation type multi-phase multi-level permanent magnet motor system includes a double-stator multi-phase composite permanent magnet synchronous motor, wherein two independent five-phase three-level inverters supplies power for stator winding ports of the motor respectively; an independent controllable rectifier supplies power for each five-phase three-level inverter; the two controllable rectifiers can share one set of LC filter at the power grid side; the LC filter includes a three-phase grid-connected inductor and a three-phase filter capacitor which is connected with the three-phase grid-connected inductor in parallel; and the first five-phase three-level inverter and the second five-phase three-level inverter are respectively connected with the two stator winding ports of the double-stator multi-phase composite permanent magnet synchronous motor. The invention also discloses a control method of the indirect matrix transformation type multi-phase multi-level permanent magnet motor system. The indirect matrix transformation type multi-phase multi-level permanent magnet motor system and the control method thereof can significantly improve reliability, power density, torque smoothness and operation efficiency of the motor driving system, and can lay the foundation of solving the technical difficulty that a high capacity motor traction driving system requires compact designs, reliable operation and energy-efficient aspects.

The present invention provides a multi-level sine pulse width modulation method. The method comprises: (1) according to the level number N of a convertor, determining the waveform transformation of carrier waveform in a single-carrier period from isosceles triangle carrier waves to laminated multi-level triangle carrier waves; (2) according to the level number N of the convertor, performing phase shift of 360 degrees / (N-1) of each laminated carrier wave; (3) comparing the modulation waves with the laminated carrier waves: when the modulation waves are larger than or equal to the laminated carrier waves, outputting high levels, and when the modulation waves are smaller than the laminated carrier waves, outputting low levels; and (4) outputting one way of PWM waveform when the modulation waves are compared to each carrier wave according to the step (3), and finally obtaining each way of PWM waveform. The modulation method provided by the invention can be utilized in a single-phase circuit and a three-phase circuit, has good output voltage harmonic wave performance and can effectively improve the utilization of direct voltage.

A fast three-phase space vector modulation method based on a three-dimensional coordinate system belongs to the technical field of power electronics. At first, that vector is map from a two-dimensional coordinate system to a three-dimensional coordinate system by using a simple coordinate change, three modulation vectors are used to synthesize the reference voltage vector, Three modulation vectorsform a modulation triangle in the three-dimensional coordinate system, detect the closest modulation vector to the origin in the modulation triangle, calculate the three-phase switching state corresponding to the vector and map it to the three-dimensional coordinate system, and scale the reference voltage vector to simplify the multilevel vector space to the two-level vector space; Finally, the duty cycle of the three-phase switching state is calculated and compared with the triangular carrier of the converter to generate the switching driving signal. The invention can realize arbitrary leveloutput only through simple addition and subtraction operation, and has extremely strong expansibility; In addition, the present invention provides several controllable factors to improve the performance of various aspects of multilevel converters.

The embodiment of the invention discloses a small hybrid mode filter with two resonant cavities, and belongs to the technical field of communication. The filter comprises n resonant cavities which areconnected in series, a metal sheet is arranged between every two adjacent resonant cavities, and n is larger than or equal to 3. A first resonant cavity and a last resonant cavity in the n resonant cavities are metal resonant cavities, and the remaining n-2 resonant cavities are dielectric dual-mode resonant cavities. The n resonant cavities are coupled through coupling windows on the metal sheets. The filter provided by the embodiment of the invention has the characteristics of compact size, low loss, high power capacity, high out-of-band rejection and good harmonic performance, so that theanti-interference capability and the spectrum utilization rate of a 5G communication system can be effectively improved, the power consumption of the 5G communication system is reduced, and the coverage range of the 5G communication system is enlarged.

A heating apparatus using an electromagnetic wave is disclosed, by which cut-of performance of an electromagnetic wave is enhanced by increasing an electromagnetic wave absorption bandwidth having cut-off performance below −70 dB. The present invention includes a door provided to an open front side of a body to be opened / closed, a choke filter having a panel type choke part arranged by at least one or more rows along an edge of the door and a filter part arranged by at least one or more rows along the choke and having a plurality of slots wherein a prescribed choke part is provided to a most inner side, a glass panel attached to an inner lateral side of the door and the choke filter, and a flange part provided to an external end portion of the door along the edge of the door to lie in a same level with an inner lateral side of the glass panel.

The invention discloses an ultrastrong damping high-voltage synchronous motor which comprises a generator stator and a generator rotor, wherein the generator stator comprises a stand, an iron core and a rotor coil, and the generator rotor comprises a magnetic pole iron core, magnetic pole coils, an ultrastrong damping winding, an alternating current exciter rotor, a rotating rectifier and a rotating shaft; and a plurality of magnetic pole coils form a complete magnetic pole winding, a plurality of axial damping slotted holes are uniformly distributed at the radial periphery of the magnetic pole iron core, a plurality of damping winding copper rods respectively penetrates into each damping slotted hole of the magnetic pole iron core, and both ends thereof are respectively welded with a damping ring to form a cage-shaped whole. The width a of a damping hole notch on the magnetic pole iron core is 6-8mm, the depth h is 0.5-1mm, and the distance b to a magnetic pole surface is 0.4-0.5mm. The damping winding of the invention has ultrastrong damping effect, so that the harmonic inhabiting capability and the dynamic performance of the invention are greatly enhanced, thereby greatly improving the capability of carrying nonlinear loads.

A heating apparatus using an electromagnetic wave is disclosed, by which cut-of performance of an electromagnetic wave is enhanced by increasing an electromagnetic wave absorption bandwidth having cut-off performance below −70 dB. The present invention includes a door provided to an open front side of a body to be opened / closed, a choke filter having a panel type choke part arranged by at least one or more rows along an edge of the door and a filter part arranged by at least one or more rows along the choke and having a plurality of slots wherein a prescribed choke part is provided to a most inner side, a glass panel attached to an inner lateral side of the door and the choke filter, and a flange part provided to an external end portion of the door along the edge of the door to lie in a same level with an inner lateral side of the glass panel.

The invention discloses an indirect matrix transformation type multi-phase multi-level permanent magnet motor system. The indirect matrix transformation type multi-phase multi-level permanent magnet motor system includes a double-stator multi-phase composite permanent magnet synchronous motor, wherein two independent five-phase three-level inverters supplies power for stator winding ports of the motor respectively; an independent controllable rectifier supplies power for each five-phase three-level inverter; the two controllable rectifiers can share one set of LC filter at the power grid side; the LC filter includes a three-phase grid-connected inductor and a three-phase filter capacitor which is connected with the three-phase grid-connected inductor in parallel; and the first five-phase three-level inverter and the second five-phase three-level inverter are respectively connected with the two stator winding ports of the double-stator multi-phase composite permanent magnet synchronous motor. The invention also discloses a control method of the indirect matrix transformation type multi-phase multi-level permanent magnet motor system. The indirect matrix transformation type multi-phase multi-level permanent magnet motor system and the control method thereof can significantly improve reliability, power density, torque smoothness and operation efficiency of the motor driving system, and can lay the foundation of solving the technical difficulty that a high capacity motor traction driving system requires compact designs, reliable operation and energy-efficient aspects.

The invention relates to a harmonic suppression device based on epitaxy delta controllable reactor connection. The harmonic suppression device comprises a first group of magnetically controlled reactors using epitaxy delta connection and a second group of magnetically controlled reactors using epitaxy delta connection, wherein the first group of magnetically controlled reactors and the second group of magnetically controlled reactors have the same type and are connected in parallel; and a three-phase iron core column of the first group of magnetically controlled reactors and a three-phase iron core column of the second group of magnetically controlled reactors have flat five-core structures. The three-phase iron core column of the first group of magnetically controlled reactors and an alternating-current working winding of the second group of magnetically controlled reactors employ the epitaxy delta connection way; an alternating-current working winding of the first group of magnetically controlled reactors uses delta forward connection as the epitaxy delta connection way; and the alternating-current working winding of the second group of magnetically controlled reactors uses delta reverse connection as the epitaxy delta connection way. According to the invention, with the connection ways of the working windings of the reactors, the harmonic performance can be improved to the great extent.

A fast three-phase space vector modulation method based on a three-dimensional coordinate system belongs to the technical field of power electronics. The present invention first utilizes the simple coordinate change to map the vector from the two-dimensional coordinate system to the three-dimensional coordinate system, and then uses three modulation vectors to synthesize the reference voltage vector, and the three modulation vectors form a modulation triangle in the three-dimensional coordinate system, and detect the modulation triangle Detect the modulation vector closest to the origin, calculate the three-phase switch state corresponding to the vector and map it to the three-dimensional coordinate system, scale the reference voltage vector to simplify the multi-level vector space into a two-level vector space; finally calculate the three-phase The duty cycle of the switch state is compared with the triangular carrier wave of the converter to generate the switch drive signal. The invention can realize arbitrary level output only through simple addition and subtraction operations, and has strong expansibility; in addition, the invention provides several controllable factors to improve the performance of various aspects of the multi-level converter.

The invention discloses a modular multi-level converter combined with series-parallel connection multiplexing, and the converter includes several sub-modules which are connected in a series connectionmultiplexing mode, and each sub-module includes n half-bridge modules and n double-coupled reactors, wherein n half-bridge modules and n double-coupled reactors in each sub-module are connected in aparallel connection multiplexing manner, and the converter can withstand larger current, and has good harmonic performance and high operation efficiency.

The invention relates to the technical field of filters, in particular to a dielectric waveguide filter for improving the harmonic performance, a radio frequency module and a base station. The dielectric waveguide filter includes dielectric bodies and at least two resonance parts located on the different dielectric bodies. The resonance parts are coupled together through coupling windows, and thecoupling windows are arranged at the edges of the dielectric bodies. The coupling windows are main-path-coupling coupling windows or cross-coupling coupling windows. The coupling windows are strip-shaped, L-shaped or U-shaped (opened rightwards), and are symmetrically distributed along the central axes of the dielectric bodies. By adopting the dielectric waveguide filter for improving the harmonicperformance, the radio frequency module and the base station provided by the invention, harmonics can be kept away from the pass band of the filter, the loss of the filter and the complexity of the manufacturing process can be reduced, and the cost can be lowered.

The invention discloses a synchronous carrier modulation method for a three-level inverter, and the method comprises the steps: carrying out the negation of a three-phase sine wave, and injecting a specific offset, and obtaining three groups of three-phase initial modulation waves; respectively selecting specific initial modulation waves for three phases in different space angle regions to obtain three-phase actual modulation waves; obtaining two groups of carriers with opposite initial directions by setting the triangular carrier frequency to be the even number times of three of the fundamental wave frequency; selecting specific initial direction carriers in different space angle areas to obtain actual carriers; and formulating a comparison rule of the actual modulation wave and the actual carrier wave, and obtaining a control signal of the three-level inverter based on comparison of the actual modulation wave and the actual carrier wave, thereby realizing synchronous carrier wave modulation for reducing the common-mode voltage. According to the method, the amplitude of the common-mode voltage can be reduced by one half while harmonic waves of multiple of three and even harmonic waves in the line voltage are eliminated, the change frequency of the common-mode voltage can be reduced by two thirds, and the method has the advantages of being simple in calculation and convenient to implement.

The invention provides a space vector modulation method of a multi-source converter, and belongs to the technical field of pulse width modulation of the multi-source converter. The space vector modulation method comprises the steps of building a neutral point potential unbalance space vector model by combining a standard right-angle coordinate system; dividing a small vector into a first vector group and a second vector group, and determining a boundary equation of a small sector comprising small vectors in the first vector group and the second vector group; determining a reference voltage vector according to the boundary equation of the small sector; calculating an action time proportion of a basic vector of the small sector; and performing hybrid modulation on the first vector group andthe second vector group according to the action time proportion so as to achieve DC-side power allocation and acquire various energy circulation modes. The problem brought by neutral point voltage unbalance is solved by a coordinate operation-based method, and the operation quantity is reduced; and hybrid modulation of the first vector group and the second vector group is employed, power allocation of a DC side is achieved by controlling action time weights of the first vector group and the second vector group, and more energy circulation modes are obtained.

A heating apparatus using an electromagnetic wave is disclosed, by which a capacity of a cavity is increased and by which cut-off performance of the electromagnetic wave and facilitation of door cleaning can be enhanced. The present invention includes a door provided to an open front side of a body to be opened / closed, a choke filter having a panel type choke part arranged by at least one or more rows along an edge of the door and a filter part having a plurality of slots wherein a prescribed choke part is provided to a most outer side, and a glass panel attached to an inner lateral side of the door and the choke filter.

The invention discloses a multi-parallel inverter motor speed regulating system and a control method of the multi-parallel inverter motor speed regulating system. The system is formed by connecting multiple inverter modules in parallel. The direct current sides of multiple inverter sub modules are directly connected with a direct current power supply with a direct current bus capacitor in parallel. The alternating current sides of the multiple inverter sub modules are connected with multiple sets of smoothing reactors respectively in series and then directly connected in parallel to drive an alternating current motor. By the adoption of the structure, modularization expansion of the motor speed regulating system is easily conducted, and the fault-tolerance performance of the motor speed regulating system is enhanced. By means of a random SVPWM method based on carrier phase shifting, switching frequency of parallel inverters is equivalently improved, switching subharmonic energy within narrow frequency bands is equalized, the harmonic performance of output currents of the parallel inverters is improved, and electromagnetic interference resistance of the motor speed regulating system is enhanced. By the adoption of a space vector synthetic technology for dynamically allocating SVPWM zero vectors, zero-sequence circulating currents between the parallel inverter modules are effectively eliminated, and normal operation of the system is guaranteed.

The invention provides a high power factor diode rectifier permanent magnet motor control method adopting a low capacity thin film capacitor. According to the method, a d-q axis specified is obtained via optimization algorithm-based off line calculation, and a PWM prediction controller is adopted for replacing a PI current controller based on conventional vector control. To compensate deviation between expected inverter output power and output power calculated based on a real time motor current and specific voltage, a voltage correction vector is added. A novel over-modulation algorithm is adopted; while voltage outputting capability of an inverter is increased, the specific voltage of a corrected inverter is enabled to be always in an inverter output voltage limiting scope. According to the control method, application of grid side high power factor control does not require any extra power factor correction circuit or input wave filter, and an input current harmonic wave component of a power grid can be suppressed. Compared with a conventional motor driver, a motor driving control solution put forward in the invention is markedly advantageous in terms of cost, size and reliability.

The invention discloses a multiple control method for a rectifier, belongs to the technical field of the rectifier, and solves the technical problems of non-ideal grid side harmonic performance and high probability of power grid resonance phenomenon of the rectifier in the existing control method. The multiple control method for the rectifier comprises the steps of obtaining set current and voltage control signals according to direct current voltages and set voltages of multiple rectifiers; performing harmonic suppression processing on input currents of the multiple rectifiers, and obtaining current control signals according to processed signals and set currents; generating modulation wave based on the voltage control signals, the current control signals and the power grid voltage; and performing carrier phase-shifting SPWM modulation according to the modulation wave to generate pulse signals so as to control the multiple rectifiers.

The invention provides a space vector modulation method of a multi-source converter and belongs to the technical field of pulse width modulation of a multi-source converter. Including combining the per unitized Cartesian coordinate system to construct the neutral point potential unbalanced space vector model; dividing the small vectors into vector group 1 and vector group 2, and determining the small sectors formed by the small vectors in vector group 1 and vector group 2 The boundary equation of the small sector; according to the boundary equation of the small sector, determine the reference voltage vector; calculate the action time ratio of the basic vector of the small sector; according to the action time ratio, the vector group 1 and the vector group 2 are mixed and modulated to realize DC Side power distribution to obtain multiple energy flow modes. The present invention adopts the method based on the coordinate operation to solve the problem caused by the unbalanced voltage of the midpoint, and reduces the calculation amount; adopts the mixed modulation of the vector group 1 and the vector group 2, and controls the action time weight of the vector group 1 and the vector group 2, The power distribution on the DC side is realized, and more energy flow modes are obtained.

The invention discloses an SVPWM synchronous over-modulation method. The method comprises: a to-be-modulated voltage vector is determined and a modulation ratio and an angle of the voltage vector arecalculated; according to the modulation ratio of the voltage vector, pre modulation of the voltage vector entering an over-modulation region is carried out; acting time of the voltage vector after premodulation is calculated; and the acting force of the voltage vector is compared with a carrier cycle to obtain an acting sequence of the voltage vector. According to the invention, transition from asynchronous SVPWM modulation to square wave modulation is realized. The SVPWM synchronous over-modulation method is suitable for the application fields like the low switching frequency.

The invention discloses a five-phase inverter random SVPWM modulation method, belonging to the technical field of multi-phase inverter drive control. In each sampling period, the sampling period is kept constant, and the PWM pulse is randomly delayed to realize the randomization of the switching period. Double randomization of vector action times. The modulation method of the present invention can greatly reduce the amplitude of high-order harmonics without affecting the performance of low-frequency harmonics, and disperse the harmonics originally concentrated around the switching frequency and its integer multiples into a wider spectrum range , so as to obtain a more continuous and uniform frequency spectrum, effectively suppress electromagnetic interference and high-frequency noise, and improve the electromagnetic compatibility of the system.