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Servo Feedback Devices and Motor Sensors
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
Both brush and brushless resolvers are available in industrial applications. Like brush motors, electrical connections in a brush resolver rely on brushes and slip rings. Because of brush wear, it is very difficult to maintain its operational reliability, especially at high speeds. To solve the problem, brushless resolvers have been developed that employ the inductive technology to couple excitation energy to the rotor and essentially require no maintenance. In this design, energy is supplied to the primary winding in the rotor through a rotary transformer. Because there are no contact parts, brushless resolvers can withstand high vibration and shock loads and are insensitive to contaminations. Therefore, they have a much longer lifetime than the brush type.
Rotary Transformer Design
Published in Colonel Wm. T. McLyman, Transformer and Inductor Design Handbook, 2017
The rotary transformer is essentially the same as a conventional transformer, except that the geometry is arranged so that the primary and secondary can be rotated, with respect to each other with negligible changes in the electrical characteristics. The most common of the rotary transformers are the axial rotary transformer, shown in Figure 19-2, and the flat plane, (pot core type), rotary transformer, shown in Figure 19-3. The power transfer is accomplished, electro-magnetically, across an air gap. There are no wearing contacts, noise, or contamination problems due to lubrication or wear debris.
Study of rotor position estimation algorithm based on back-EMF voltage for dual-winding fault-tolerant permanent magnet motor
Published in Automatika, 2022
Yonghan Liu, Jingwei Zhu, Zhibin Wang, Yan Liang
Recently, the fault-tolerant permanent magnet machine has been proposed, which offers high-power density, excellent electrical and magnetic isolation capability and good fault tolerance capability. The dual-winding fault-tolerant permanent magnet motor (FTPMMM) has two sets of independent three-phase concentrated armature windings on alternate teeth [1]. Combined with the excellent characteristics of FTPMM and double-redundancy control system, it has the advantages of large space utilization rate, high reliability and low cost, which has attracted wide attention of scholars. In traditional motor position detection system, the rotor position can be obtained by photoelectric encoder, rotary transformer and other devices, which inevitably increase the complexity and affect the dynamic and static performance of the system [2]. It goes against the original intention of designing dual-winding FTPMM to enhance the system reliability. Therefore, the study of estimating the rotor position of dual-winding FTPMM that can improve its accuracy and stability has important implications.
Excess pore pressure observation in marine sediment based on Fiber Bragg Grating pressure sensor
Published in Marine Georesources & Geotechnology, 2019
Tao Liu, San-Peng Li, Hai-lei Kou, Wan-li Chai, Guan-li Wei
During installation, the attitude of equipment can be determined by the three-dimensional attitude meter in advance. A rotary transformer was also installed in the manipulator for probe displacement recording. In this test, the penetration rate was controlled to be 0.5 m/min not the standard CPT rate of 2 cm/s, in order to prevent over range of FBG pressure sensor. After installation, excess pore pressure was recorded continuously for one week. The monitoring phases include the dissipation test, long-term observation after penetration and pulling out test. The dissipation test is to check the short-term performance of proposed probe. The long-term observation after penetration is to investigate the excess pore pressure variation caused by tide. The location of FBG pressure sensors in sediment after installation was shown in Figure 9. It should be noted that as the sensor of No. 1 in the probe was broken during installation, there is no data recorded. The recorded data by No. 2, No. 3 and No. 4 sensors were used for analysis in the study.
Research of the feedforward control system of 3-axis stable platform based on disturbance observer
Published in Systems Science & Control Engineering, 2018
Sui Tao, Cheng Fei, Liu Xiuzhi, Li He, Wang Yi
The conventional three-closed-loop compound control system of three-axis stabilized platform is illustrated in Figure 2, it consist of a current loop, a stabilization loop and a position loop, which respectively adopt PID, PI, and P control. In the process of analysis, the couplings among frames are ignored, and the control structures of three subsystems are basically same. Therefore, the pitching frame is taken as an example to analyse and study the system performance. The detection of current loop refers to the examination of Hall elements installed inside the drive. The rate gyroscope, which is taken as a feedback element for the stable loop, mainly applies to the isolation of carrier’s disturbance and the command of tracking loop output. The tracking loop adopts high-precision rotary transformer as feedback element. This paper uses the literature’s (Li & Zhong, 2011) three-loop compound PID control method to calculate the relevant parameters of its current loop, stable loop, and tracking loop. And the computation process is no longer repeated here.