Detecting faults in rotors of PM drives

In this paper, effects of the speed-controller bandwidth in permanent magnet synchronous machines are discussed. Motor current signature analysis has been used to detect rotor faults in synchronous machines.     

防止变压器短路损坏事故的技术措施

电力变压器是城乡电网的主要设备,但又是较脆弱的设备.近几年我市电网曾发生多起10 kV馈线短路,造成35 kV和110 kV电力变压器绕组变形损坏事故.究其原因,有些是制造厂家设计不良,压紧结构强度不足;有些则是运行部门管理维护不当,甚至是由于运行人员误操作所致.因此,防止变压器短路损坏事故的发生,必须采取综合的技术措施.     

Axial flux interior PM synchronous motor: parameters identification and steady-state performance measurements

This paper presents different measurement and identification approaches applied to a nonconventional permanent-magnet (PM) synchronous machine, namely, the novel axial flux interior PM (AFIPM) synchronous motor. The nonconventional geometry of the AFIPM motor requires a dedicated discussion on the parameter identification subject. In the paper, the standstill frequency-response test and the standstill time-response test on the AFIPM prototype are presented. On the basis of these tests, the d- and q-axes circuit parameters are chosen. To confirm the validity of the standstill tests, the load tests have also been performed. Furthermore, the load tests provide some preliminary AFIPM machine performance results and additional information on the saturation phenomena. The d- and q-axes equivalent circuits parameters obtained by the performed measurements are analyzed and compared. Finally, the most appropriate AFIPM machine model is selected.     

Predictive current control with current-error correction for PM brushless AC drives

The performance of the conventional predictive current control (PCC) when applied to a permanent-magnet brushless ac (PM BLAC) drive is analyzed. A technique is proposed to reduce the current errors that arise due to the inaccuracies in the system parameters and the nonideal behavior of the inverter during a steady-state operation. In addition, a current-regulated delta modulator is employed to achieve a fast dynamic response during a transient operation. The performance of the proposed PCC, which is simple to implement on a low-cost fixed-point DSP, is demonstrated experimentally.     

500 kV母线短路故障的分析

描述了外高桥二厂3.7500 kV母线三相短路故障过程中系统的频率、潮流、电压和低压释放情况,并对此进行了分析,还仿真校核了系统短路电流和有关机组功角,提出了电网运行和管理的相关建议.     

Adaptive and robust speed control of interior permanent magnet synchronous motor drives

This paper presents a robust speed controller for field oriented controlled interior permanent magnet synchronous motor (IPMSM) drives. The proposed controller is designed using integral variable structure control (IVSC) combined with linear quadratic regulator (LQR). The LQR scheme is used to decide the optimal feedback gain to shape the system dynamics by tuning the IVSC switching plane to guarantee the robustness of the control algorithm. The complete drive is implemented in real-time using digital signal processor (DSP) control board DS1102. The tracking properties and robustness of the proposed scheme are examined through both simulations and experimental work. It guarantees accurate control performance in the presence of parameter variations, step speed change and load disturbances. The performance of IPMSM drive system with a conventional proportional-integral (PI) controller is presented in comparison with the proposed controller. The results show a significant improvement in both the transient and steady state responses over the conventional PI controller.     

Sensorless control of interior permanent-magnet machine drives with zero-phase lag position estimation

This paper presents an improved method to estimate rotor motion states for an interior permanent-magnet machine drive. This approach is based on the estimation of a saliency-based electromotive force (EMF) in the stationary reference frame using a state filter. The spatial information obtained from the estimated saliency-based EMF is used in an observer to estimate the motor motion states. By using the commanded torque as a feedforward input to the observer, the motion state estimation has zero-phase lag, providing a very-high-bandwidth estimate.     

Enhanced current control of high-speed PM machine drives throughthe use of flux controllers

This paper compares various types of current controllers, including a novel method based on flux control. A proportional integral (PI) control method is used initially, to control the current in a high-speed permanent-magnet synchronous machine. The performance of this simple PI loop is presented, Various improvements to the PI controller are investigated, and the change in performance examined. A new current control scheme based on a flux-linkage model of the machine is introduced. The performance of the model-based control is demonstrated and compared with the performance of the PI current controller. Factors affecting the accuracy of the model-based control are given. By incorporating these factors into the model, the performance of the flux controller is further enhanced     

A saturating lumped-parameter model for an interior PM synchronousmachine

This paper presents a lumped-parameter magnetic model for an interior permanent-magnet synchronous machine. The model accounts for the effects of saturation through a nonlinear reluctance-element network used to estimate the q-axis inductance. The magnetic model is used to calculate inductance and torque in the presence of saturation. Furthermore, these calculations are compared to those from finite-element analysis with good agreement     

Achieving a constant power speed range for PM drives

Flux weakening has long been a standard approach in obtaining a constant power speed range for traction drives with commutator motors. There is much interest in using permanent magnet (PM) commutator motors or, preferably, electronically commutated PM motors for such applications. Some PM motor designs, such as those using inset or buried magnets, have been proposed to achieve flux weakening. This paper questions the desirability of the flux weakening approach for a number of applications where energy efficiency is of prime importance, such as in electric vehicles. For an acceptable increase in the rating of some of the semiconductor devices, standard PM commutator motors and switched PM motors with surface-mounted magnets can be used and a significant reduction in power loss can be achieved     

The steering effect PM motor drives for automotive systems

The steer-by-wire (SBW) system requires the use of enhanced fuel economy, assist action given two motor drives, the first for the mechanical steering system and the second for the torque feedback to the steering wheel. An interior permanent magnet (IPM) synchronous motor is used for the steering actuator whereas a fractional-slot surface-mounted permanent magnet (SPM) synchronous motor is used for the torque feedback.     

Air conditioner response to transmission faults

This paper describes two multi-phase faults events which occurred during periods of high air conditioning use. There was a significant loss of load in these events which is attributed to air conditioner motor protection. The overall response of the transmission system is simulated using induction motor models based on the characteristics of a typical residential air conditioner compressor motor. The sensitivity of factors such as fault location, fault duration and excitation system performance is also investigated     

控制和降低短路电流水平措施在华东电网的应用

分析了华东500 kV主环网短路电流水平。总结、归纳和分析了华东电网近年来应对短路容量超标矛盾的经验和措施。描述了2006~2007年华东电网控制和降低枢纽变电站短路电流水平的方案。     

Selection of short-circuit protection and control for Design Emotors

The purpose of this article is to give users of Design E motors electrical application information concerning the selection of the appropriate motor disconnecting means, motor branch-circuit short-circuit protection, motor circuit conductor, motor controller and motor overload protection, and guidance concerning torque characteristics. The authors describe how motor efficiency is increased and how the design changes related to increased efficiency affect the mechanical and electrical characteristics of motors. They also review the requirements of Article 430 of the 1996 National Electrical Code and provide generic application tables that compare the protection and control requirements of Design E motors with those of Designs B, C, and D     

Development and implementation of a hybrid intelligent controller for interior permanent-magnet synchronous motor drives

A hybrid neuro-fuzzy scheme for online tuning of a genetic-based proportional-integral (PI) controller for an interior permanent-magnet synchronous motor (IPMSM) drive is presented in this paper. The proposed controller is developed for accurate speed control of the IPMSM drive under various system disturbances. In this work, initially different operating conditions are obtained based on motor dynamics incorporating uncertainties. At each operating condition a genetic algorithm is used to optimize the PI controller parameters in a closed-loop vector control scheme. In the optimization procedure a performance index is developed to reflect the minimum speed deviation, minimum settling time and zero steady-state error. A fuzzy basis function network (FBFN) is utilized for online tuning of the PI controller parameters to ensure optimum drive performance under different disturbances. The proposed FBFN-based PI controller provides a natural framework for combining numerical and linguistic information in a uniform fashion. The proposed controller is successfully implemented in real time using a digital signal processor board DS 1102 for a laboratory 1-hp IPMSM. The effectiveness of the proposed controller is verified by simulation as well as experimental results at different dynamic operating conditions. The proposed controller is found to be robust for applications in an IPMSM drive.     

Optimized INFORM measurement sequence for sensorless PM synchronous motor drives with respect to minimum current distortion

In this paper, a standard measurement sequence for INFORM-based sensorless position estimation of permanent-magnet synchronous motors is analyzed. Its properties with respect to the current deviation caused by the INFORM measurement are pointed out. Based on that a modified measurement sequence with minimum current deviation and minimum time demand is introduced. Measurement results verify the improvement of the modified measurement sequence: The current distortion is reduced significantly, resulting in reduced additional losses. Additionally, several measurement results concerning the performance of the sensorless position estimation under various load conditions are presented. Successful industrial applications are given.     

An improved stator flux estimation in steady-state operation fordirect torque control of induction machines

This paper presents an improved stator flux estimation technique based on a voltage model with some form of low-pass (LP) filtering. In voltage-model-based stator flux estimation, an LP filter is normally used instead of a pure integrator to avoid integration drift problem due to DC offset, noise, or measurement error present in the back electromotive force. In steady-state condition, the LP filter estimator will degrade the performance and efficiency of the direct torque control (DTC) drive system since it introduced magnitude and phase errors, thus resulting in an incorrect voltage vector selection. The stator flux steady-state error between the LP filter and a pure integrator estimator technique is derived and its effect on the steady-state DTC drive performance is analyzed. A simple method is proposed to compensate for this error which results in a significant improvement in the steady-state drive performance. Simulation based on this technique is given and it is verified by experimental results     

Electronic line-shafting control for paper machine drives

The current synchronized motion control methods used in paper machine drives are not designed to possess the inter-shaft stiffness properties which were responsible for the coordinating force inherent in classical, mechanically coupled paper machines. Consequently, these controllers cannot easily maintain coordination for all operating conditions. This paper presents the application of an “electronic line-shafting” control technique which serves to replicate and even improve on the historical, mechanical line-shafted properties. This technique was tested on a four-shaft experimental setup to evaluate such control during periods of drive-limited torque as well as sectional drive load disturbances. The experimental results demonstrate that the “electronic line-shafting” technique significantly improves the coordination, robustness, and overall stability of paper machine drives subjected to realistic physical limitations     

Slip-frequency detection for indirect field-oriented control drives

This paper presents a new technique to detect the slip angular frequency in induction motor drives with indirect field-oriented control (IFOC). Slip frequency is calculated by processing the effects exerted by an additional high-frequency signal on the zero-sequence stator voltage. By measuring such a zero-sequence voltage, it is possible to evaluate the air-gap flux and detect the slip frequency in order to implement an IFOC algorithm. According to the proposed approach, rotor time constant errors are not influent as in conventional field-oriented control schemes, thus, complex tuning or compensation techniques are not required. Simulations and experimental tests are performed to evaluate the consistency of the proposed approach.     

Characteristics of PM synchronous motor drives with a trapezoidal EMF

A permanent magnet synchronous motor (PMSM) with nonsinusoidal electromotive force (EMF) generates torque ripple even if the sinusoidal PWM inverter drives the PMSM. A new modified trapezoidal modulating signal for PWM inverter suitable for PMSM drive with nonsinusoidal EMF is proposed in this paper. A new modulating signal for the PMSM drive is determined by the condition of reducing torque ripple of the motor with various trapezoidal EMF. When the PWM inverter using modified trapezoidal modulating signal drives the PMSM having a nonsinusoidal EMF, the torque ripple of the motor can be reduced, the DC link voltage utilization is improved, and reduction of switching loss can be obtained. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 62–71, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20441