37results about How to "Reduce the risk of resonance" patented technology

The present invention relates to a turbine wheel (10) comprising: - a plurality of first blades (20) and a plurality of second blades (22), at least one of the first blades being adjacent to at least one of the second blades; a disc (12) having an axis of rotation, at a periphery of which the blades are mounted, each of the blades having a tip secured to a root engaged in a housing (16) opening at the periphery of the disc, each of the blades comprising a polarizing means consisting of a ledge positioned between the tip and the root of the said blade, the ledges of the first blades (20) having an azimuthal length (L1) different from the azimuthal length (L2) of the ledges of the second blades (22); a damping device (30) positioned at least between the said two adjacent blades, the said damping device being positioned between the ledges of the blades (20, 22) and the periphery of the disc (12); the mass of the roots (22b) of the second blades (22) is less than the mass of the roots (20b) of the first blades (20) while the profiles of the tips (20a, 22a) of the first and second blades are identical, the result of this being that the resonant frequency of the first blades is different from the resonant frequency of the second blades, and the second blades (22) are engineered to break before the first blades (20) if the turbine wheel begins to overspeed.

The invention discloses a four-degree-of-freedom hybrid excitation starting / power generation integral bearingless switched reluctance motor. The four-degree-of-freedom hybrid excitation starting / powergeneration integral bearingless switched reluctance motor consists of two dual-stator motors with same structure in coaxial connection in the axial direction; torque windings are wound on outer stator teeth of the two dual-stator motors respectively; suspension windings are wound on inner stator teeth of the two dual-stator motors; the two dual-stator motors share the same rotor and the same rotating shaft; a circular ring-shaped permanent magnet sleeving the outside of the rotating shaft is fixedly connected between stator yoke parts of two inner stators of the two dual-stator motors, and the permanent magnet is axially magnetized. Integral operation of starting and power generation is realized, a suspension current magnetic circuit and a torque current magnetic circuit are of mutual independence without interference in the rotor, and the two motor torque windings are serially connected together, so that the application of a controller is reduced.

The invention discloses a method for designing vibration reliability of rail transit electronic products, which comprises acquiring vibration excitation frequency information in an actual operating environment of rail transit electronic products; obtaining product natural frequency information based on an initial design scheme of rail transit electronic products; Perform matching analysis on the natural frequency information and the vibration excitation frequency information. When the matching condition that the natural frequency avoids the vibration excitation frequency is met, the initial design scheme is determined to be the vibration reliability design scheme; otherwise, the quality and / or the product in the initial design scheme are adjusted or stiffness for scheme optimization until the vibration reliability design scheme is determined. The design method provided by the invention can propose a design scheme satisfying vibration reliability, can minimize the risk of product resonance during operation, and improve the operation reliability of rail transit electronic products.

The invention discloses a flexible DC high-frequency resonance suppression method, system and equipment, including: under normal working conditions, the input volume and output volume of the adaptive filter of the virtual power grid are completely isolated physically, and the harmonics of the actual electrical volume will not Reflected on the virtual electrical quantity, it has the effect of suppressing harmonics. When the effective value of the actual AC voltage input is reduced from the normal value to meet the preset conditions, the virtual electrical quantity is completely equal to the actual electrical quantity, realizing complete real-time tracking of the actual electrical quantity, and improving the dynamic characteristics of the power system at the moment of failure; After a period of full tracking, if the effective value of the actual AC voltage is less than the preset threshold, it will enter adaptive tracking until the actual electrical quantity returns to a stable value. The invention can reduce the risk of high-frequency resonance of the flexible DC, avoid deterioration of the dynamic characteristics of the flexible DC under fault conditions, avoid damage to devices or equipment caused by overstress, and improve the safety of the flexible DC fault ride-through.

This application discloses a photovoltaic inverter with multiple MPPT units, wherein: one inverter unit is preset in each MPPT unit as a carrier synchronization master, and other inverter units are carrier synchronization slaves; The MPPT unit with the number of units equal to 1 has 1 carrier synchronization master and 0 carrier synchronization slaves; the carrier synchronization master in 1 MPPT unit is connected to all carrier synchronization slaves in the same MPPT unit and all other MPPTs through a communication bus The carrier synchronization master in the unit; the carrier synchronization master in the MPPT unit whose quantity of each inverter unit in all the remaining MPPT units is greater than 1 is also connected to all carrier synchronization slaves in the same MPPT unit by a communication bus, In order to reduce the high-frequency circulating current in the same MPPT unit, and reduce the risk of LCL resonance when multiple inverter units are running in parallel on the AC side.