5 results about "Impedance plane" patented technology

This invention relates to the field of bearing steel ball defect detection technology, and discloses a method and system for bearing steel ball defect detection combining eddy current and ultrasonic testing. The method includes: first, acquiring the eddy current impedance plane trajectory and ultrasonic A-scan waveform during the continuous rolling process of the bearing steel ball, obtaining preliminary estimates of the eddy current and ultrasonic defect depths respectively, and using these estimates to invert the hardness gradient parameter set of the current bearing steel ball; then, reconstructing the conductivity distribution function and sound velocity distribution function based on the hardness gradient parameter set, performing gradient correction on the preliminary estimates of the eddy current and ultrasonic defect depths to obtain the true defect depth value, and combining this with the designed hardened layer depth to perform a three-level defect classification judgment. This invention can eliminate the dual-modal depth positioning deviation caused by the material radial gradient, achieving high-precision detection and classification judgment of bearing steel ball defect depth.

The application discloses a network-structured grid-connected inverter instability prevention and positive design method, comprising the following steps: establishing an impedance model and a control loop model of the network-structured grid-connected inverter; defining a multi-target constraint condition and confirming an impedance to be designed based on the impedance model and the control loop model; drawing an impedance curve Bode diagram of each sample and finding out a main difference frequency band, sampling the impedance curve in the frequency band to obtain a labeled impedance frequency response data point set; performing data screening processing on the labeled impedance frequency response point; training the processed labeled data set to obtain a feasible region and a forbidden region of an impedance plane and a decision boundary thereof; and searching and optimizing a surrounding neighborhood of a preliminary feasible sample based on the obtained impedance feasible region and forbidden region to form a parameter feasible region. The application further provides a network-structured grid-connected inverter instability prevention and positive design device. The method provided by the application can realize instability prevention and positive design.

Presentations showing eddy current (EC) test results can be generated and displayed. For example, amplitude or phase values ​​associated with an eddy current measurement signal can be presented graphically, such as by aligning an index of the amplitude or phase value with a shape representing the object under test, where the index corresponds to the location on or within the shape from which the eddy current measurement signal was obtained. In another example, the visual attributes of the displayed index of the amplitude or phase value can be assigned based on the defect class, such as using different colors corresponding to different defect classes, when the visual attributes are defined by regions within the impedance plane. The use of attributes to identify defects can be carried out either separately or in combination with alignment with the shape of the index.

This invention discloses a method for symmetrical loss-of-excitation protection of variable-speed pumped-storage units based on a downward-throwing impedance circle, belonging to the field of generator relay protection. The method includes: real-time acquisition of the measured voltage and current at the generator terminals of the variable-speed pumped-storage unit, and calculation of the measured impedance at the generator terminals; constructing a symmetrical loss-of-excitation power circle criterion on the operating power plane of the variable-speed pumped-storage unit; further transforming the symmetrical loss-of-excitation power circle criterion onto the impedance plane to obtain the downward-throwing impedance circle criterion; if the measured impedance at the generator terminals enters the downward-throwing impedance circle and remains within the circle for a time greater than t, then initiating an emergency shutdown of the unit. This invention can quickly detect and judge symmetrical loss-of-excitation faults on the generator side, such as three-phase winding open circuits and complete loss of pulses in the generator-side converter, and can also schedule timely shutdowns for maintenance of the variable-speed pumped-storage unit. Furthermore, this method has high reliability and can effectively ensure the safe operation of the power grid and the variable-speed pumped-storage unit, possessing significant engineering application value.

The utility model provides an anti-static precision circuit board, which relates to the technical field of circuit boards and comprises a substrate layer, conductive layers are fixedly mounted on two sides of the substrate layer, one side of each conductive layer is coated with a bonding layer, one side of each bonding layer is connected with a bonding pad layer, and the bonding pad layers are arranged on the substrate layer. Wherein two sides of the surface of one bonding pad layer are respectively provided with an electrostatic protection diode, the surface of the bonding pad layer is coated with an anti-static coating, and the surface of the bonding pad layer is provided with a conductive covered edge. According to the utility model, the multi-layer board design is adopted, a complete ground plane is close to the wiring, static electricity can be more quickly coupled to a low-impedance plane so as to protect key signals, and the two static electricity protection diodes are designed on the surface of the bonding pad layer so as to consume static electricity energy and prevent electric arcs released by static electricity accumulation from damaging the circuit board; therefore, the circuit board is protected in the aspects of electrostatic consumption and release.