对照同步电动机原理鉴识频率自控的电机

术语"同步电机"频繁出现在自控变频电源馈电的电机系统有关文献中,本文强调按同步电机作用原理鉴识频率自控的电机。在同步电机内功角是个自变量,是电机处于不同运行状态下的标志。凡频率自控的电机,不论是在电枢侧还是励磁的转子侧实施频率自控,两侧磁动势轴线之间或者磁场轴线之间的夹角就必定受到箝制,便不存在增减有一定自由度的功角了。通过与同步电机原理对比并参照箝位概念,容易领悟频率自控的电机之合理归属。

自控变频为属性的直流电动机及广义直流电动机

自控行为是直流电动机及广义直流电动机的基本特征。广义直流电动机是直流电动机的同类型电机,也是直流电动机的新发展。自控变频反映直流电动机的属性,广义直流电动机是对电机本体采取自控变频措施的电动机。依托数学推理阐明了同步电动机本无自控行为,以电机本体为主件与自控电气配件组成的机电一体化电机,对电枢电流的频率及相位实施自控,从而产生气隙磁场钳位,使广义直流电动机呈直流电动机的性能特征。

与直流电动机同类型的自控式同步电动机

自控式电动机专指有直流励磁磁极的一种电机。从动态转速的观点,审视同步电动机和直流电动机的两种不同构建模式,它们的区别在于是否允许转子角速度相对于电枢磁动势角速度有所变动,以及由此呈现的不同基本特征。指出自控式的交流电动机是具有箝位效应的直流电动机的新发展。从交流电枢的视角探讨直流电动机原理有助于为工程实践提供有益的启示。

一种用于射频锁相环的快速自动频率控制电路

基于TSMC 180nm CMOS工艺,设计了一种应用于GNSS接收机锁相环的快速自动频率控制电路。采用准闭环结构,并通过二分查找的方式寻找最优电容阵列控制字,缩短了频率粗调节时间,从而缩短了锁相环的锁定时间。仿真结果表明,当AFC电路工作时,PLL锁定时间为7μs,其中,频率粗调节时间约为4μs。

从交流电枢的视角更新对直流电动机的认识

三种基本类型的电机可按频率特征来分辨,直流电动机其实是频率自控的交流电动机。无换向器电动机本是直流电动机的新发展并不会转型为同步电动机的。

Design and implementation of digital closed-loop drive control system of a MEMS gyroscope

In order to effectively control the working state of the gyroscope in drive mode, the drive characteristics of the micro electromechanical system （MEMS） gyroscope are analyzed in principle. A novel drive circuit for the MEMS gyroscope in digital closed-loop control is proposed, which utilizes a digital phase-locked loop （PLL） in frequency control and an automatic gain control （AGC） method in amplitude control. A digital processing circuit with a field programmable gate array （FPGA） is designed and the experiments are carried out. The results indicate that when the temperature changes, the drive frequency can automatically track the resonant frequency of gyroscope in drive mode and that of the oscillating amplitude holds at a set value. And at room temperature, the relative deviation of the drive frequency is 0.624 ×10^-6 and the oscillating amplitude is 8.0 ×10^-6, which are 0. 094% and 18. 39% of the analog control program, respectively. Therefore, the control solution of the digital PLL in frequency and the AGC in amplitude is feasible.

A 5-GHz frequency synthesizer with constant bandwidth for low IF ZigBee transceiver applications

A fully integrated integer-N frequency synthesizer is implemented.The synthesizer is designed for low intermediate frequency （IF）ZigBee transceiver applications.Techniques used to make the loop bandwidth constant across the whole output frequency range of the voltage controlled oscillator（VCO）are adopted to maintain phase noise optimization and loop stability.In-phase and quadrature（IQ）signals are generated by a 1/2 frequency divider at the output of the VCO.The synthesizer is fabricated in 0.18 μm radio frequency（RF） complementary metal oxide semiconductor transistor （CMOS）technology.The chip area is 1.7 mm2.The synthesizer is measured on wafer.It consumes totally 28.8 mW excluding output buffers from a supply voltage of 1.8 V.The measured phase noise is -110 and -122 dBc/Hz at the offset of 1 and 3 MHz from a 2.405 GHz carrier,respectively.The measured reference spur at a 2 MHz offset from a 2.405 GHz carrier is-48.2 dBc.The measured setting time of the synthesizer is about 160 μs.

基于DSP的永磁同步电机控制系统设计

本文介绍了一种以DSP控制芯片为核心,以全数字方式进行自控频率调压调速的永磁同步电机控制系统。实验证明该系统具有良好的工作特性。

Frequency control system based on power factor control of asynchronous motor

Deduced the relationship between the power factor (PF) and the angular fre-quency according to the simplified equivalent circuit of asynchronous motor, forming a power factor auto-control system. An anti-interference circuit was also introduced in the middle voltage link of inverter to avoid the shift of the optimum PF point caused by the change of the load and the reliable run of the control system was assured. The experi-ment results show that it has a good self-adaptation in the whole scope of speed ad-justment and an obvious economization on energy while it runs under load.

Fuzzy control on automatic frequency tracking of ultrasonic vibration system with high power and high quality factor Q

In order to realize automatic tracking drift of resonance frequency of ultrasonic vibration system with high power and high quality factor Q, adaptive fuzzy control was studied with a self-fabricated ultrasonic plastic welding machine. At first, relations between amplitude of vibration and frequency as well as main loop current and amplitude of vibration were analyzed. From this analysis, we deduced that frequency tracking process of the vibration system can be concluded as an optimizing problem of one dimensional fluctuant extremum of main loop current in vibration system. Then a method of self-optimizing fuzzy control, used for the realization of automatic frequency tracking in vibration system, is presented on the basis of serf-optimizing adaptive control approach and fuzzy control approach. The result of experiments shows that the fuzzy self-optimizing method can solve the problem of tracking frequency drift very well. Response time of tracking in the system is less than 50 ms, which basically meets the requirements of frequency tracking in ultrasonic plastic welding machine.

Research and Implementation of Multi-Point Automatic Synchronization Based on Active Frequency Tracking Control

Reliable connection of turbine generators in complex main wiring structures to the power grid through a plurality of switches is a new key problem,referred to as multipoint automatic synchronization(MPAS),in automatic control systems(ACS).In this paper,different methods of voltage-frequency and phase-difference control are analyzed,and a control methodology based on active frequency tracking(AFT)is presented.Through the establishment of the multi-point automatic synchronization model and the analysis of the governor transfer function with this control method,the important control parameters and automatic process control sequence are summarized.The correctness and effectiveness of the designed methodology are inspected through on-site testing,and the importance of the function and selection of parameters are also explored.