108results about How to "Good harmonic suppression effect" patented technology

The invention discloses a double frequency band filter of a SIR coaxial cavity. The double frequency band filter of the SIR coaxial cavity comprises a CQ-type topological structure formed by coupling of a coaxial SIR in magnetic and galvanic modes. The coaxial SIR is composed of a rod-shaped inner layer metal transmission line, an outer layer barrel-shaped metal wall and a middle medium layer, wherein the outer layer barrel-shaped metal wall shares the same axis with the inner layer metal transmission line which is formed by connecting of two coaxial transmission lines with different diameters. A terminal opening end coaxial borehole is formed at the top end of a terminal opening end of the metal transmission line, and a tuning screw is placed at the top end of the terminal opening end of the metal transmission line to tune. The double frequency band filter is provided with the CQ-type topological structure of 8 cavities, two transmission zeroes are generated on the outside of a double frequency band, so that out-of-band suppression performances are greatly improved. Compared with a traditional duplexer, the double frequency band filter is improved on the aspects of size miniaturization and design complexity in quality mode. The double frequency band filter has the advantages of being small, low in insertion loss, high in double frequency selection properties and the like. The demands on filter performances by a modern communication system are met, and the double frequency band filter can be widely applied in double frequency band mobile communication systems.

The invention discloses a stepped impedance resonator (SIR) coaxial-cavity band-pass filter, which is of a comb-shaped filter structure formed by coupling an SIR fundamental resonator unit. The SIR fundamental resonator is composed of three parts of a bar-shaped inner layer metal transmission line, an outer layer cylinder metal wall in coaxial with the inner layer metal transmission line and a middle medium layer. The inner layer metal transmission line is an SIR resonance rod formed by combining two sections of coaxial transmission lines with different diameters. An open circuit coaxial bored hole and a tuning screw are arranged at the top end of the open circuit end of the metal transmission line, and the top end of the open circuit end of the metal transmission line is provided with a windowing coupling screw coupling structure and an input output direct coupling structure. The filter has good spurious frequency rejection characteristics, is small in size compared with a traditional base station, meets requirements of modern communication systems for miniaturization, low insertion loss, high selectivity and wide attenuation band on filters, and can be widely applied to modern mobile communication systems.

A harmonic suppression resonator comprises a plurality of waveguide resonators that resonate in TE mode, in which harmonic suppression resonator, adjoining resonators are coupled via a plurality of coupling windows. Four coupling windows 33bc1, 33bc2, 33bc3 and 33bc4 are provided between a resonant region 51b and a resonant region adjoining the resonant region 51b. These coupling windows allow fundamental wave modes of the adjoining resonators to be coupled mainly by magnetically coupling. The coupling windows 33bc3 and 33bc4 allow second harmonic modes of the adjoining resonators to be electrically coupled, and the coupling windows 33bc1 and 33bc2 allow the second harmonic modes of the adjoining resonators to be magnetically coupled. By causing the amount of the electrically coupling and the amount of the magnetically coupling to be substantially equal, the coupling of the second harmonic modes is negated, whereby propagation of the second harmonic is blocked.

The invention relates to an LCL grid-connected inverter impedance remodeling method for restraining the influence of power grid background harmonic waves. The method comprises the following steps of:establishing a frequency domain model of an inverter grid-connected system, under the condition of considering a power grid operation mode, determining the value range of the system cutoff frequency,and introducing common point voltage feedforward compensation to perform advanced compensation on the phase of a frequency band near the cutoff frequency of the output impedance of the inverter; and increasing the phase angle stability margin of the system; and performing optimizing according to the target of the suppression effect of the background harmonic of the power grid and by taking the factors that the increasing of the fundamental frequency impedance of the inverter does not influence the output efficiency of the inverter and the phase stability margin of the medium-low frequency bandafter correction is larger than 30 degrees as constraint conditions, and determining the maximum value of the gain compensation coefficient of the compensation link within a limit value. The LCL grid-connected inverter impedance remodeling method for restraining the influence of power grid background harmonic waves has the advantages that the suppression effect on the background harmonic waves ofthe power grid is optimal while the stability of the grid-connected system is considered.

The invention discloses a second-order-odd-repetitive-controller-based odd harmonic current suppression method of a magnetic levitation rotor. A magnetic levitation rotor kinetic model including rotor mass unbalance and sensor harmonic is established; and a second-order-odd-repetitive-controller(SOORC)-based odd harmonic current suppression method of a magnetic levitation rotor is employed. The SOORC has a second-order inner membrane structure for odd harmonic frequency suppression, so that the harmonic suppression capability on a harmonic frequency changing or uncertain condition can be improved and thus the control robustness of the system for the harmonic frequency changing or uncertain condition can be improved. With phase hysteresis-lead compensation, the steady performance and dynamic performance of the system are improved, so that odd harmonic current components generated by a magnetic bearing coil in a magnetic levitation rotor can be suppressed. The method is suitable for suppression of odd harmonic current components of the magnetic levitation rotor system with rotor mass unbalance and sensor harmonic.

A space vector pulse width modulation (SVPWM) method for suppressing a common-mode voltage of a multiphase motor includes the following steps: (1) dividing all basic vectors of the multiphase motor into q types, and selecting therefrom x types having equal common-mode voltage magnitude of which an absolute value is smallest; (2) for each type in the x types of basic vectors, structuring y classes of auxiliary vectors according to an optimization model; (3) synthesizing reference vectors by virtue of the auxiliary vectors to obtain functioning time of basic vectors functioning in each switching period; and (4) obtaining an optimal functioning sequence of the basic vectors functioning in each switching period with fewest switching operations of a converter as a purpose. The present invention may effectively suppress a magnitude and frequency of the common-mode voltage of the multiphase motor without increasing calculation complexity or reducing other performance indexes, has a good harmonic suppression effect on a line voltage and a phase current and high steady state and dynamic performance of a torque and a rotating speed, and can be used for a high-performance multiphase power generation system, a multiphase excitation system and a multiphase driving system.

The invention discloses an electric railway electric energy quality comprehensive treatment device control method. A single-phase multi-winding transformer secondary side is provided with a railway power regulator and a thyristor control filter. The railway power regulator is provided with more than two converters sharing a DC (direct current) side capacitor to form a back-to-back structure and connected with each other in parallel; and the AC (alternating current) output ends of the converters are connected to the M-phase and T-phase power supply seats through a connection electric reactor and a transformer. A winding of each transformer secondary side is respectively provided with more than two groups of thyristor control filters connected with each other in parallel; and each thyristor control filter is provided with more than two groups of filter branches connected with each other in parallel. The railway power regulator balances the active power between the M-phase and T-phase power supply seats. The thyristor control filter compensates for the reactive power of the M-phase or T-phase power supply arm and filters the harmonic wave. The method disclosed by the invention can realize comprehensive treatment of the negative sequence, harmonic wave and reactive power of the electric railway, and can properly reduce the active capacity so as to achieve the aims of improving the treatment effect and reducing the cost.

The invention discloses a radio frequency power amplifier in a two-stage stack structure, comprising an input matching circuit, an output bandwidth matching circuit, and a two-stage amplifier circuit formed by cascading interstage matching circuits. A preceding stage of the two-stage amplifier circuit is a driving stage, and a following stage thereof is a power stage; a radio frequency signal source is connected with a gate electrode of a transistor in the bottommost layer of the driving stage through the input matching circuit, a drain electrode of a transistor in the uppermost layer of the driving stage is connected with one end of the corresponding interstage matching circuit, the other end of this interstage matching circuit is connected with a gate electrode of a transistor in the bottommost layer of the power stage, and a drain electrode of a transistor in the uppermost layer of the power stage is connected with a load through the output bandwidth matching circuit. This circuit enables improvements in the voltage withstand capacity, output voltage swing, operation bandwidth, power efficiency, power gain and maximum output power of the power amplifier and provides better harmonic suppression effect.

The invention provides a composite virtual harmonic impedance control method for a grid-connected inverter. The method mainly comprises the steps of: sampling the voltage of a grid-connected point of the inverter and calculating an active component V<PCCd> and a reactive component V<PCCq>; using a high-pass filter to extract V<PCCd_h> and V<PCCq_h>, and calculating order current harmonic parts i*<d_h> and i*<q_h>; calculating a direct current voltage error [delta]U<dc> and calculating an order current fundamental wave part active component i*<d_f>; and setting an order current fundamental wave part reactive component i*<q_f> as zero; and calculating inverter output voltages u, u and u<c>, and controlling the breakthrough and cutoff of a switch tube in a three-phase full-bridge inverter circuit via PWM. The composite virtual harmonic impedance control method of the invention is to simulate parallel branches of a resistance branch and a resistance-inductance branch at a harmonic wave frequency band by controlling the grid-connected inverter so as to suppress the distortion of grid-connected voltage VPPC caused by a harmonic source I<h> or power grid background harmonic wavea V<g>. Compared with a traditional resistor type virtual harmonic impedance control method for the grid-connected inverter, the composite virtual harmonic impedance control method has stronger system stability and better grid-connected voltage harmonic suppression capacity.

The invention discloses a harmonic suppression method of a bidirectional converter of an energy accumulation unit in a wind and light accumulation system. The harmonic suppression method comprises the steps of: extracting a quintic harmonic voltage and a septic harmonic voltage and a current of a power grid; then figuring out corresponding voltage compensation quantities of v alpha 5th, v beta 5th, v alpha 7th and v beta 7th; adding voltage quantities v alpha and v beta obtained through decoupling control with a current of an inner ring to obtain output reference quantities V alpha and V beta; and carrying out SVPWM (Space Vector Pulse Width Modulation) on the output reference quantities V alpha and V beta to obtain switching signals of switching on and switching of a controllable switch tube of a three-phase bridge arm of a bidirectional converter. Because the quintic harmonic and the septic harmonic are taken into account in control quantities, the problem of pollution of high-order harmonics due to nonlinear factors of the bidirectional converter is eliminated. The harmonic suppression method is suitable for a harmonic suppression process of the bidirectional converter used by the energy accumulation unit in renewable energy source systems such as the wind and light accumulation system, and can achieve better harmonic suppression effect under the condition of no need of additional hardware input.

The invention discloses an internal mold based frequency adaptive phase-locked loop modeling method, and relates to the technical field of signal processing. The method comprises the following steps that a synchronous rotating coordinate system phase-locked loop SRF-PLL model is constructed; a frequency adaptive filter IMAF is used, a positive, negative and zero sequence separated calculation module PNZSC extracts a positive sequence fundamental wave voltage of the power system, and a low pass filter module in the SRF-PLL model is replaced; and at the same time, a source decoupling-end normalized phase-locked loop SUN-FLL is used to provide estimated frequency for the frequency adaptive filter IMAF, and finally the IMAF-PLL model is obtained. The method has a good frequency selection effect and high stability, and the phase-locked loop is more robust to resist voltage fluctuation and frequency fluctuation.

The invention relates to a frequency mixer with high-order harmonic wave inhibiting ability and an inhibiting method for high-order harmonic waves, and belongs to the technical field of microwaves. The frequency mixer comprises a power division network, two local oscillator harmonic wave inhibiting networks, two field effect tubes and a 3db coupling bridge, local oscillator signals firstly pass through the power division network, then are fed into the field effect tubes, radio frequency signals pass through the 3db coupling bridge, then are fed into the field effect tubes, the radio frequency signals and the local oscillator signals are subjected to frequency mixing in the field effect tubes, the local oscillator harmonic wave inhibiting networks inhibit the local oscillator harmonic wave signals generated by nonlinear effect of the field effect tubes, obtained signals are subjected to power synthesis through the 3db coupling bridge, and finally intermediate-frequency signals are output. By the frequency mixer with high-order harmonic wave inhibiting ability and the inhibiting method for the high-order harmonic waves, LO (local oscillator) harmonic wave inhibiting ability can be substantially improved without influences on frequency mixing performance of the frequency mixer, and the inhibiting method for the high-order harmonic waves is especially suitable for circumstances that LO harmonic waves fall into an IF (intermediate frequency) band.

The invention discloses a control method for torque pulse of a segmented harmonic current suppression switched reluctance machine. According to the method, real-time torque difference of a motor torque is calculated on the basis of a set average torque, the torque difference is converted to current difference according to a torque-current relation, and a non-linear current compensation value of each phase is solved out. A harmonic current which is injected according to segments is superposed to a rectangular reference current, the harmonic injection size and the harmonic current coefficient of a corresponding segment are determined, so that the form of a current waveform of a zone is more accurately controlled; and under current chopping control, the torque output of the motor is further changed, and the problem of motor torque pulse caused by phase current fluctuation in a commutation period during running of the switched reluctance machine is improved. The purpose of suppressing the torque pulse can be achieved under the current chopping control, and the algorithm has wide universality and transportability.

The invention discloses a harmonic current suppression method, device, equipment and storage medium. The method comprises the steps that the dq axis current error parameter corresponding to the current three-phase stator current is acquired; proportional integral resonance control is carried out on the dq axis current error parameter, and a control parameter is determined according to the control result; and closed-loop control is carried out on a motor according to the control parameter. According to the method, the current stator current harmonic suppression scheme can be optimized, and the technical problems of large calculation amount, more resource consumption, complicated implementation and poor harmonic suppression effect in a software control policy are solved.

The invention provides an electric vehicle bidirectional charging discharging system design method. The electric vehicle bidirectional charging discharging system design method comprises steps that S1, an electric vehicle charging discharging model constituted by a line side power supply, a PWM rectifier, a DC-DC converter, and a storage battery is established; the PWM rectifier adopts a three-phase PWM rectifier; S2, a valuing range of a main circuit parameter is determined; the main circuit parameter comprises an AC side inductive parameter and a DC side capacitive parameter; S3, a three-phase PWM rectifier control strategy is set, and theoretical analysis of harmonic characteristics is carried out; S4, a simulation model is established, and the charging discharging system is analyzed, compared, and verified in a simulated way. The electric vehicle bidirectional charging discharging system design method is advantageous in that the three-phase PWM rectifier is used for rectification and inversion, and then network access requirements are satisfied by corresponding current and corresponding voltage without requiring harmonic suppression measures.

The invention discloses a digital signal processor (DSP)-based staggered single phase space vector pulse modulation gridding device. The device comprises a space vector pulse modulation device, a staggered control device and a control unit, wherein the control unit comprises a DSP control unit; the space vector pulse modulation device is a single-phase space vector pulse modulation device; and all bridge circuits of the staggered control device are staggered and operated in parallel according to a 360 DEG / N of phase at the same frequency, wherein N (N is more than or equal to 2) is the number of the current parallel circuits. The device adopts a DSP staggered single-phase space vector pulse width modulation (SVPWM) technology, facilitates digitized management, reduces device volume, has a compact circuit structure, improves the dynamic performance of power supplies, optimizes switch times, reduces switch loss and improves the utilization rate of (direct current) DC voltage. The inverter technology is superior to the conventional inverter technology, is suitable for the inversion of new energy and grid power generation, and has higher harmonic suppression capability and a wide application prospect.

The invention relates to a high-frequency structure design method for an ultra-wide band helix traveling wave tube, belonging to the technical field of ultra-wideband traveling wave tubes. The method comprises the following steps: firstly determining the inside diameter of a helical line; then, under the premise that the inside diameter remains unchanged and through the adjustment of the pitch and the inside diameter of a wing sheet, making high coupling impedance one of the high-frequency characteristics of an input section and enabling dispersion characteristic of an output section to realize super anomalous dispersion so that the pitches and the inside diameters of wing sheets of the input section and the output section can be determined respectively. For the characteristic of high coupling impedance, a helical forward wave can be more synchronized with an electronic beam, greatly increasing the output power. For the characteristic of super anomalous dispersion at the output section, the synchronization between a higher harmonic wave and an electronic beam is destroyed, thus achieving a better harmonic suppression effect. The high frequency structure of the invention can improve the output power and suppress harmonic waves, and the output power is more than 115W in the frequency range of 4.5 to 18GHz and the second harmonic wave at 4.5GHz is less than -5dBc.

The invention provides an improved complex vector PI controller employing current harmonic suppression system and method of a permanent magnet synchronous motor , belonging to the technical field of motor control. A system and method for suppress current harmonics of a permanent magnet synchronous motor improve a complex vector PI controller and a q-axis current PI controller, A d-axis current PIcontrol is connected in parallel, so that that output of the improve complex vector pi controller is separate from the output of the pi controller, A new q-axis and d-axis voltage command is obtainedto control the ac component of q-axis and d-axis currents and to suppress current harmonics.

The invention provides a microwave strip transmission line circulator with a harmonic suppression function, which comprises a permanent magnet, a metal pole piece, microwave ferrites and an outer case. One strip line central conductor is installed among the microwave ferrites and comprises three 120 DEG Y-junction resonators and three matching circuits, and each matching circuit comprises an open parallel circuit and an inductance type transmission line. The three inductance type transmission lines of the strip line central conductor are respectively connected with an electrical conductor at a port of the circulator radially at the equal intervals of 120 degrees. The microwave strip transmission line circulator is provided with a built-in open parallel circuit with one quarter wavelength and provides the functions of a trap filter to suppress harmonic waves.

The invention discloses a direct-current power supply system applicable to pure electric bus charging stations and a charging station thereof. The direct-current power supply system comprises a three-phase power grid which is connected with a primary winding of a harmonic shielding transformer. A secondary winding of the harmonic shielding transformer is connected with a rectifier module and a filter. A static var generator is connected in parallel between the three-phase power grid and the primary winding of the harmonic shielding transformer. Pure electric bus charging station filtering and reactive power compensation are realized, the harmonic content of the pure electric bus charging station is reduced, and the power factor of the pure electric bus charging station is improved.

The invention discloses a power supply network harmonic suppression method and system capable of resisting impulse noise interference. On the basis of an active filter method, the self-sensing actuator principle is used for fusing a sensing part and an execution part together so as to enable the two parts to transmit information mutually, the defect that when errors occur in sensing signals, harmonic waves cannot be eliminated, or even the signals are worse can be overcome, and meanwhile, the harmonic suppression effect can also be improved; during updating of sub-harmonic weights, the RLS algorithm is adopted, therefore, the defect that step size factors are different to determine in the LMS algorithm is overcome, and the convergence rate is increased. Fractional lower order statistics-fractional lower order correlation (FLOC) is used for processing signals, so that the power supply network harmonic suppression method and system have a certain suppression effect on impulse noise interference. During frequency estimation, the PHD algorithm is used, implementation is simple, the calculated amount is low, a formula for calculating an autocorrelation matrix in the algorithm is improved according to an FLOC calculation method, the influence of impulse noise can be suppressed, and therefore frequency estimation is more accurate.

The invention discloses a high-efficiency broadband power amplifier and a radio frequency transceiver. The high-efficiency broadband power amplifier comprises an input port, a broadband input matchingcircuit, an input broadband direct-current bias circuit, a power amplification transistor, an output broadband direct-current bias circuit, a low-pass filtering network, an auxiliary matching transmission line and an output load, the input port is connected with one end of the broadband input matching circuit. The other end is connected with the grid electrode of the power amplification transistor; the drain electrode of the power amplification transistor is connected with one end of the output broadband DC bias circuit and one end of the low-pass filtering network. The other end of the low-pass filtering network, the auxiliary matching transmission line and the output load are connected in sequence, the input broadband direct-current biasing circuit is connected with the broadband inputmatching circuit, and a source electrode of the power amplification transistor is grounded. The invention can work in a very wide frequency band range, is suitable for various communication frequencybands, is small in size, is high in efficiency, and is suitable for a plurality of radio frequency systems.

A high-power power quality comprehensive compensation device comprises a main circuit (1), a main control algorithm implementation circuit (2) and a detection and protection circuit (3). The device transmits an analog signal which is output after passing through an analog signal conditioning circuit to the main control algorithm implementation circuit (2) through the analog signal conditioning circuit in the detection and protection circuit (3). After analog-digital conversion, the control algorithm of the high-power power quality comprehensive compensator is achieved through a DSP chip. A power device IGBT in the main circuit (1) is controlled to emit compensation current in the reverse direction of harmonic current or reactive current in detected load current. Meanwhile, energy compensation can also be performed on unbalanced current of an unbalanced load, and the composite compensation function of the device is achieved.

The invention relates to a medium-wave harmonic filter used for a medium-wave navigation transmitter. The medium-wave harmonic filter consists of five sections of filtering units, wherein each section of filtering unit forms a filtering channel; each section of filtering unit is a seven-order low-pass filter which is formed by connecting four capacitors, three inductors and four relays; the capacitors and the inductors form a filter circuit part of the seven-order low-pass filter; and a relay coil end in each section of filtering unit is connected with a three-eight decoder in an external control unit. Because the relays are controlled by a level signal output by the three-eight decoder of the external control unit in each section of filtering unit, the switching between the filtering units of the control filter is controlled; the harmonic suppression performance of the medium-wave transmitter is improved, so that the second harmonic suppression performance and the third harmonic suppression performance are improved; the switching of intelligent control mode control frequency bands is realized in the medium-wave transmitter; and thus the medium-wave harmonic filter can be applied to 100W, 200W and 500W series medium-wave transmitters and has the advantages of stable work, reliable performance and popularization value.

This invention provides a method for controlling voltage transformer magnetic path and eliminating electric net harmonic wave, belonging to power system harmonic controlling and electron technology field. The method comprises the following steps: adding harmonic controlling winding in the present secondary side winding, connecting in series current checker in load side of the transformer, harmonic separator is linked behind the current checker, the output end of harmonic separator is linked to the two ends of controlling winding, by changing the controlling winding's linkage way and designing the discharge coefficient of current checker and number of turns of controlling winding, making the magnetic linkage generated by controlling winding is the same with harmonic magnetic linkage by transformer load side in size while different in direction, so that it can restrict and eliminate harmonic wave. The invention has the advantages of simple devices, less investment and good economical benefit.

The invention discloses a method for suppressing a harmonic wave of an interference signal based on the electromagnetic compatibility and belongs to the field of electromagnetic compatibility. The method comprises steps that an interference measuring signal to be analyzed is firstly subjected to sliding window average to suppress quantized nose causing the harmonic wave, a frequency spectrum of a corresponding smooth filtering signal is obtained, and then the smooth frequency spectrum carries out weighted correction on a frequency spectrum of the measuring signal, so that the harmonic wave of the interference measuring signal is suppressed. The method only utilizes the interference measuring signal to suppress harmonic wave noise without requiring other measurement or equipment, and the method is easy to carry out.

The invention belongs to wind power generation equipment, and relates to a charging circuit for an energy storage capacitor of a high-power wind power converter. The circuit includes a machine-side rectifier circuit and a grid-side inverter circuit connected between the generator and the power grid; the machine-side rectifier circuit is composed of an IGBT power unit, and is connected to the generator through a machine-side switch; the grid-side inverter circuit consists of It is composed of IGBT power unit, and connected to the power grid through LCL filter circuit and grid-side switch in sequence; its feature is that the charging resistor is connected in parallel at the grid-side switch, and the charging resistor is controlled by the charging switch connected in series. The invention can ensure that the DC bus voltage reaches a capacitor safety voltage range in advance before the converter starts to work, and prolongs the service life of the capacitor; it not only has a simple circuit structure and low cost, but also has fast charging speed, high charging voltage and harmonic suppression effect it is good.

The invention provides a direct-current side harmonic suppression system and method of a 12-pulse rectification system on the basis of an interleaved Boost APFC circuit, and belongs to the technical field of power electronics. The system and method aim to solve the problems that an existing direct-current side harmonic suppression system and method of the 12-pulse rectification system are complex in structure of a direct-current side active circuit, difficult in obtaining synchronizing signals and poor in harmonic suppression effect. The interleaved Boost APFC circuit is adopted to serve as the direct-side active circuit of the system, a voltage signal of a balance reactor secondary winding is sampled to serve as a standard triangular wave signal, the standard triangular wave signal and a load circuit current signal are multiplied to serve as a current reference signal, and interphase balance reactor secondary winding currents are controlled through signal processing and a control circuit to track secondary winding voltage, so that the balance reactor secondary winding currents and the secondary winding voltage are identical in frequency and phase, and the amplitude of the balance reactor secondary winding currents is half that of a load circuit current value. The system and method are applied to the field of harmonic suppression of the 12-pulse rectification system.

The invention provides a quarter-structured substrate integrated waveguide bipass live-line tune filter. The filter includes a dielectric substrate, a quarter copper-clad structure on the upper surface of the dielectric substrate, a lower copper metal on the lower surface of the dielectric substrate. The quarter copper-clad structure is provided with a metalized through hole that forms the substrate integrated waveguide, the left lower side of the quarter copper-clad structure is a 50-ohm input microstrip line, the right side of the L-shaped groove in the quarter copper-clad structure is provided with a complementary square spiral resonance ring, the right side of the 50-ohm input microstrip line is a big square metal plane, the center of the big square metal plane is provided with an inverted recessed punching metal sheet, the center of the inverted recessed punching metal sheet is provided with a center through hole, and six square metal pads are arranged under the quarter copper-clad structure and the 50-ohm input microstrip line. The filter has the characteristics of small size, low insert loss, continuous adjustment of center frequency, high outband suppression, convenient DC feed loading, fast tuning speed, and convenient tuning.

The invention discloses an 18-pulse phase shift rectifier transformer. The 18-pulse phase shift rectifier transformer comprises a transformer framework and three windings, wherein the transformer framework comprises three iron core pillars, each winding comprises primary windings and secondary windings, the primary windings are wound on the three iron core pillars respectively, after each secondary winding is divided into three sections of secondary sub-windings, the secondary windings are wound on the primary windings respectively in a cake type, and a first flux leakage iron core is arranged at one side between each primary winding and the corresponding secondary winding. The 18-pulse phase shift rectifier transformer can well suppress harmonic waves and has good heat radiation performance.