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 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 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.