A microcontroller-based sensorless stator flux-orientedasynchronous motor drive for traction applications

A sensorless stator flux-oriented asynchronous motor drive has been realized by using a low-cost single-chip microcontroller. A motor state observer has been implemented, which showed excellent performances, particularly at low-speed operation. Two different experimental realizations have been developed, with rated powers equal to about 1.5 and 30 kW, respectively, and good results have been obtained in both cases. The theoretical approach, main design choices, and most significant experimental results are presented     

Flying capacitor multilevel inverters and DTC motor drive applications

In this paper, the requirements imposed by a direct torque control (DTC) strategy on multilevel inverters are analyzed. A control strategy is proposed in order to fulfill those requirements when a flying-capacitor multilevel inverter is used. Simulation and practical results will confirm the performance of the proposed strategy when using the multilevel inverter to control an induction motor by the DTC principle. Also, the advantages of using a multilevel inverter with a DTC strategy are shown by simulation results.     

Photonic integration for high-volume, low-cost applications - [Topics in optical communications]

To date, photonic integration has seen only limited use in a few optical interface applications. The recently adopted IEEE draft standards for 40 Gb/s and 100 Gb/s Ethernet single-mode fiber local area network applications will change this situation. Although first generation implementations will use discrete components based on existing technologies, long-term requirements for significant reduction in cost, size, and power of 40 Gb/s and 100 Gb/s transceivers will lead to a broad demand for photonic integration. Both hybrid planar lightguide circuit and monolithic photonic integrated circuit are feasible approaches that meet the requirements of the new IEEE standards.     

A novel random PWM technique with low computational overhead and constant sampling frequency for high-volume, low-cost applications

A novel random pulse-width modulation (PWM) technique for three-phase voltage-source inverters, characterized by low computational overhead, a variable switching frequency, and a constant sampling frequency, is presented. The technique is based on two strategies: 1) the so-called arithmetic PWM (APWM), which yields the same switching patterns as the classic space-vector modulation, but with minimal computational effort and 2) randomization of switching periods by varying the delay of switching cycles with respect to corresponding sampling cycles. Simplicity of the technique, named a variable-delay random PWM (VDRPWM) method, allows its implementation in cheap, low-end processors. It makes the VDRPWM the best choice for high-volume, low-cost applications, such as domestic and automotive ac drives and UPSs. The random aspect of the technique has a mitigating effect on the acoustic and electromagnetic noise emitted by the supplied system. This feature has been confirmed by experiments with a 40-hp induction motor drive.     

基于滑模控制的异步电机无速度传感器DTC研究

建立了一种滑模速度观测器,用于电机转速的精确观测。该观测器充分利用电机状态方程具有的结构特点,设计出简单有效的速度估算方法,在转子磁链的估算中无须用到转子时间常数和转速等信息,提高了观测器对于参数误差的鲁棒性。将所建立的观测器和空间电压矢量脉宽调制技术(SVPWM)结合对电机进行控制,进一步提高了系统的调速性能。仿真结果验证了基于滑模控制理论的异步电机无速度传感器直接转矩控制系统的可行性以及对参数误差的鲁棒性。     

System control and management for low-cost high-volume GaAs manufacturing

With a portfolio consisting of Metal Semiconductor Field Effect Transistors (MESFET), Pseudomorphic High Electron Mobility Transistors (pHEMT), Heterojunction Insulated Gate Field Effect Transistors (HIGFET), and Indium Gallium Phosphide Heterojunction Bipolar Transistors (InGaP-HBT) technology, one factory has embarked on a mission to become a leader of cost and volume gallium arsenide (GaAs) manufacturing. Separate new product and new technology introduction systems have been developed and employed. Furthermore, several manufacturing and yield improvement systems, designed primarily for high-volume silicon factories, have been implemented. Additionally, a comprehensive cost-reduction project was implemented to bring wafer costs to benchmark levels.     

A low-cost sensorless technique for load torque estimation in ahybrid stepping motor

This paper presents a method of torque measurement in a hybrid stepping motor without the use of speed or position sensors. It is shown that torque ripple can be minimized by appropriate shaping of the phase-current pulses and that efficiency can be maximized when the level of mechanical load applied to the shaft is known. A controller is described which generates a signal related to the mechanical load by observation of the phase-current profile using a novel low-complexity technique. Practical results are presented, showing the torque estimation relative to measured torque     

A start-up method for a speed sensorless stator-flux-orientedvector-controlled induction motor drive

This paper describes a zero-speed start-up method of a speed sensorless stator-flux-oriented direct vector-controlled induction motor drive with the help of a machine current model that does not use any speed signal. The machine starts smoothly with vector control at finite developed torque and then transitions to the standard direct vector-control mode with the voltage model signals as the speed begins to develop. The direct vector-control mode with voltage model uses programmable cascaded low-pass filters for flux-vector synthesis and enables the drive to operate from zero speed to field-weakening mode. As the drive speed falls to zero, the drive again transitions to start-up mode, so that it can be smoothly started again. The performance of the start-up scheme has been verified on a 100 kW electric vehicle drive     

An improved sensorless vector-control method for an induction motor drive

In the present paper, a new improved sensorless vector-control method for an induction motor drive is presented. The proposed method is based on an improved closed-loop stator-flux estimator, based on the dynamic model of the asynchronous motor, which achieves precise stator-flux estimation over a wide area of operation. This new stator-flux estimator ensures stability of the overall control scheme in a very-wide-speed operation area, as it will be shown in this paper. The rotor-speed-estimation method is based on an observer based on the model reference adaptive systems (MRAS) theory. The control scheme is based on a stator-flux-oriented direct vector-control method, where both flux and speed controllers are optimal tuned. In addition, implementation of the proposed method is based on a simplified algorithm capable of running in a low-cost microcontroller, which is discussed in detail. Also, the motor-drive system, including the stator-flux estimator, the speed estimator, and the control logic are simulated and some characteristic simulation results are presented. These results reveal that the proposed method is able to obtain precise flux and speed control over a wide operation area, including very low operating frequencies.     

A low-cost programmable clock generator for switched-capacitor circuit applications

This paper presents two improved circuit techniques that allow the design of a low-cost programmable clock generator using a ring oscillator for low-frequency switched-capacitor applications. The first technique aims at reducing the frequency of the oscillator with small capacitors by proposing a Miller current-starved inverter ring oscillator. For identical values of integrated components in implementation, the proposed ring oscillator reduces the oscillation frequency by 5 times over the conventional ring oscillator and 3 times over the conventional current-starved inverter ring oscillator. This benefits the relaxation of PSRR requirement and the reduction of substrate noise coupling in mixed-signal circuits. The second technique aims at enhancing the reliability of the programmed data by proposing orthogonal fusible link trimming circuit. The experimental results have verified that the programming range of 56 kHz to 1.042 MHz is achieved using discrete-step tuning on small capacitor values from 0.375 pF to 5.625 pF together with frequency division by four divider stages, whilst the jitter is less than 300 ps at ±10% variation in a 5 V supply in the entire tuning range. Wing Foon Lee was born in Singapore. He had worked as an application engineer for more than two years. He received his B.Eng., M.Eng. and Ph.D. degrees in Electrical & Electronic Engineering from Nanyang Technological University, Singapore in 1996, 1999 and 2005 respectively. His research interest is on low power analog circuit design, high precision readout circuits and signal-conditioning circuits for sensor applications. P. K. Chan was born in Hong Kong. He received the B.Sc. (Hons) degree from the University of Essex, Colchester, U.K., in 1987, the M.Sc. degree from the University of Manchester, Institute of Science and Technology (U.M.I.S.T.), Manchester, U.K., in 1988, and the PhD degree from the University of Plymouth, U.K. in 1992. From 1989 to 1992, he was a Research Assistant with the University of Plymouth, working in the area of MOS continuous-time filters. In 1993, he joined the Institute of Microelectronics (IME) as a Member Technical Staff, where he designed CMOS sensor interfaces for industrial applications. In 1996, He was a Staff Engineer with Motorola, Singapore where he developed the magnetic write channel for Motorola 1st generation hard-disk preamplifier. He joined Nanyang Technological University (NTU), Singapore in 1997, where he is currently an Associate Professor in the School of Electrical and Electronic Engineering and Program Director [analog/mixed-signal IC and applications] for the Center for Integrated Circuits and Systems (CICS). He holds four patents and is an IC Design Consultant to local and multi-national companies in Singapore. He has also conducted numerous IC design short courses to the industrial companies and design centers. His research interests include circuit theory, amplifier frequency compensation techniques, sensing interfaces for integrated sensors, biomedical circuits and systems, integrated filters and data converters.     

Current-mode control for sensorless BDCM drive with intelligent commutation tuning

The winding current response speed and the adequate commutation significantly affect the control performance of a sensorless brushless dc motor (BDCM) drive. In this paper, the studies about these two issues to enhance the performance of BDCM drive are made. First, the sensorless inverter-fed BDCM drive with a proposed current command generation scheme is established. An intelligent commutation instant tuning technique is developed to pursue better motor torque generating characteristics. For achieving this goal, the motor drawn line current minimization is employed as the performance index in making the commutation tuning. After generating the current command with adequate commutation, a robust current-mode controller is further developed and applied to greatly speed up the square wave current tracking response and the response is rather insensitive to the machine parameter and back electromotive force (back-EMF) changes. In Addition, a simple starting method and a speed estimation approach are also proposed. Some experimental results are provided to demonstrate the validity of the proposed control method.     

A sensorless switched reluctance drive system using a self-inductance estimating technique

This paper proposes a new method for estimating the shaft position of a switched reluctance motor (SRM). The shaft position of the SRM is obtained by on-line estimation of the self-inductances of the motor, and a closed-loop drive system can thus be achieved. The drive system performs well in both the pulse-width-modulated (PWM) region and the single pulse region. The adjustable speed range of the system is from 20 rev/min to 2000 rev/min. In addition, the drive system is automatically started from standstill to a required speed and exhibits good transient and load disturbance responses. The detailed theoretical analysis and several experimental results are presented in the paper. First, the basic principle of the proposed method is explained. The self-inductance estimating technique is derived by using the mathematical model of the SRM. Then, the relationship between the self-inductance and the shaft position of the motor is discussed. Next, a starting technique is presented. It is then shown how a 32-bit microprocessor system is used to estimate the position and speed, speed-loop control, and the generation of three-phase current commands. Several simulated and experimental results validate the theoretical analysis.     

Development of a hybrid flywheel/battery drive system for electric vehicle applications

Today's electric vehicles are severely limited in multistop and go driving range and accelerating capability by the lead acid battery's inability to handle high power peaks while maintaining maximum energy storage capability. A hybrid flywheel/battery system can be used to isolate the battery from the accelerating power peaks, and should recover a substantial part of the braking energy. This paper describes the development of a small, high speed, lightweight flywheel/ ac synchronous motor alternator sealed energy storage package coupled into the battery and dc drive motor system through a simple rectifier/inverter power circuit. This system stores just enough energy in the rotor of the machine for one start-stop cycle. Provision is made to add a flywheel to store energy for several cycles, or enough energy for climbing or descending long grades. The fields of the two machines are electronically controlled to achieve optimum performance and effective energy utilization.     

Extended-range PMSM sensorless speed drive based on stochasticfiltering

The paper describes the design of a high-performance sensorless permanent magnet synchronous motor (PMSM) drive, capable of starting at full torque even from standstill and able to deliver full torque in 1:12 speed range. Experimental setup, hardware circuitry and software implementation are described into details. Particular emphasis is given to the software control algorithms, that were specifically studied to enhance the overall system performance     

Disturbance torque estimation in a sensorless DC drive

The estimation of the disturbance torque in a sensorless DC motor drive is carried out by extending the classical observer theory. Three estimation schemes are formulated according to the representation of the disturbance torque and the processing of the observer states. In addition to the disturbance torque, all the schemes deliver an estimation of the motor speed. Steady-state accuracy and dynamics of the schemes are first determined in nominal conditions, identifying the scheme with the best performance. The effects of variations in the motor parameters are then analyzed, with the finding that a proper modeling of the motor makes the steady-state estimation of the disturbance torque insensitive to any variation. As a test, the schemes are applied to a sensorless DC motor drive for both compensating for the disturbance torque and closing the speed loop. The responses obtained with the best-performance scheme are reported     

Design and implementation of sensorless techniques for switched reluctance drive systems

This article proposes two different methods for estimating the shaft position for a switched reluctance motor (SRM). Method 1 uses the self-inductance estimation technique to obtain the rotor position. First, by on-line measuring the slope of the stator current and compensating for the back electromotive force (EMF) effect, the self-inductance of the SRM can be detected. Then, the shaft position of the motor can be estimated according to the self-inductance. Method 2, on the other hand, uses the phase-locked loop technique to generate high-frequency signals. These signals can be used to estimate the shaft position of the SRM. The two proposed methods are compared and discussed in the article. Several experimental results are shown to validate the theoretical analysis. The adjustable speed range of the system is from 10 to 3000 rpm. Additionally, the proposed drive system can automatically start from a standstill to a setting speed.     

A high-performance sensorless indirect stator flux orientation control of induction motor drive

A new method for the implementation of a sensorless indirect stator-flux-oriented control (ISFOC) of induction motor drives with stator resistance tuning is proposed in this paper. The proposed method for the estimation of speed and stator resistance is based only on measurement of stator currents. The error of the measured q-axis current from its reference value feeds the proportional plus integral (PI) controller, the output of which is the estimated slip frequency. It is subtracted from the synchronous angular frequency, which is obtained from the output integral plus proportional (IP) rotor speed controller, to have the estimated rotor speed. For current regulation, this paper proposes a conventional PI controller with feedforward compensation terms in the synchronous frame. Owing to its advantages, an IP controller is used for rotor speed regulation. Stator resistance updating is based on the measured and reference d-axis stator current of an induction motor on d-q frame synchronously rotating with the stator flux vector. Experimental results for a 3-kW induction motor are presented and analyzed by using a dSpace system with DS1102 controller board based on the digital signal processor (DSP) TMS320C31. Digital simulation and experimental results are presented to show the improvement in performance of the proposed method.     

A 65-nm low-noise low-cost ∑ △ modulator for audio applications

This paper introduces a low-noise low-cost ∑ △ modulator for digital audio analog-to-digital conversion.By adopting a low-noise large-output swing operation amplifier,not only is the flicker noise grea...     

High dynamic speed sensorless AC drive with on-line model parametertuning for steady-state accuracy

Controlled speed sensorless AC motor drives have reached a stage of development permitting good dynamic performance above 3% of rated speed. However, the accuracy of the rotor speed estimation under load remains sensitive to parameter errors of the internal machine model. This paper presents an approach that ensures high steady-state speed accuracy in addition to high dynamic performance. To eliminate the speed estimation error, the machine parameters are adapted online, based on the evaluation of rotor slot harmonic effects. A stator flux-oriented control scheme is implemented in a digital signal processor system to demonstrate the robustness of the speed estimation to parameter variations. Experimental results demonstrate that the control system advantageously combines high dynamic performance with accuracy of speed estimation     

无传感器无刷直流电机(永磁同步电机)驱动的动态性能

本文主要阐述在梯形波和正弦波下无传感器换向的动态过程。以前各类无传感器换向只运用于矢量驱动和步进电机。处理需要实时进行,而目前高速无传感器换矢量运算还无法实现。霍尔器件和编码器被用作主要的换向指示器。它们具有梯形波和正弦波的换向能力,但是利用编码器的正弦波换向需要相应的算法控制才能够让电极在一定的高速情况下正常运行。如今,超过100Mps(直线编码)、带有高速MOSFET、IGBT和智能能量模块的微处理器以及DSP控制已经将直流无刷电机(永磁同步电机)驱动提到了一个新的高度。无传感器换向算法在低电感高速电机中已经应用。应用梯形波或者正弦波的无传感器换向技术现在也已经非常普遍。尽管梯形波换向现在仍然是主要方法,但是正弦波换向技术发展也很快,预计不久就会成为主要的换向方式。