A novel startup scheme of stator-flux-oriented vector-controlled induction motor drive without torque jerk

This paper proposes a novel zero-speed startup scheme of a stator-flux-oriented speed-sensorless vector-controlled induction motor drive that does not generate any torque jerk. A programmable cascaded three-stage low-pass filter (LPF) method is used for flux vector estimation. Usually, a torque jerk is generated at the vector control transition due to time delay in developing the stator flux by the three-stage LPF. At standstill condition, an algorithm is derived that calculates the stator flux using only the stator currents. A feedforward control strategy of the stator flux is developed to eliminate the torque jerk during transition from the standstill mode to the vector control mode. The performance of the newly developed startup scheme has been verified by simulation and then experimentally on a 3-hp induction motor drive, where the control was implemented by a 32-bit TMS320C30-type digital signal processor. The performance of the drive was found to be excellent in both simulation and experiment.     

MRAS-based speed sensorless control scheme with stator resistance identification function for vector-controlled induction motor drives

This paper describes a new scheme for the speed sensorless control of the vector-controlled induction motor drive. Based on the model reference adaptive system (MRAS) theory, the rotor speed of the induction machine is estimated with a full-order adaptive observer. The estimated speed then is used as the signal for the vector control and the speed control. To accurately estimate the speed at the lower speed range, the value of the stator resistance also is identified at the same time and then is used to modify the resistance value set in the observer. The resulting system is verified to be hyperstable with Popov's criterion. As a result, this drive can operate stably in a wide range of speed even at zero speed. Also, it is shown theoretically that neither speed nor resistance of the rotor can be identified at the same time because these two parameters are dependent on each other. Simulation results and experiments also show that the scheme is effective.     

A 150-kVA vector-controlled matrix converter induction motor drive

This paper describes the design, construction, and testing of a 150-kVA closed-loop vector-controlled matrix converter induction motor drive. The primary objective of this research effort is to evaluate the utility of the matrix converter in electric vehicle applications, primarily for motor control. A prototype converter has been built using 600-A 1400-V insulated gate bipolar transistors. Closed-loop vector control has been implemented and tested using a 150-hp induction motor load. This paper presents the design of this converter along with practical test results, representing the largest matrix converter built to date.     

矢量控制异步电动机的自适应控制和参数辨识

在矢量控制异步电动机数学模型的基础上,针对电机转子电阻和负载转矩变化的不确定性,应用非线性控制的理论,设计了一个渐近跟踪负载转矩和转子电阻实际值的非线性辨识算法,实现了参数的自动跟踪,并建立了非线性自适应控制的方案。仿真结果表明,辨识算法具有快捷准确的优点,使系统具有一定的鲁棒性和较好的稳、动态性能。     

Neural network-based stator voltage compensator for low-frequency operation of a vector-controlled induction motor drive

The stator field-oriented sensorless vector control method is receiving wide attention from the standpoints of being sensorless and less dependent on the motor parameters. However, this method has a problem at low speeds because actual stator voltage does not coincide with the corresponding reference voltage owing to the quantization error in the controller, the discrete-time process, the forward voltage drop of switching devices, and the dead time of the inverter. In this study, an artificial neural network-based voltage compensator is proposed to reduce the voltage error between the reference and the actual voltages. The proposed method was performed on an experimental system and the results were found to be excellent.     

Hyperstability of the full-order observer for vector-controlled induction motor drive without speed sensor

Vector-controlled induction motor drive systems without speed sensors have been widely studied. Speed estimation can be treated as a problem of parameter estimation under the theory of MRAS (model reference adaptive systems). In such cases, the convergence and robustness of the system are major issues. In this paper, we discuss the stability of an MRAS, that includes a full-order adaptive observer of the induction motor and is used for estimating the rotor speed and identifying the stator resistance. It is verified that, under some conditions, the transfer matrix in the forward path of the MRAS is strictly positive-real and that the non-linear block in the feedback path satisfies Popov's criterion. As a result, the system is hyperstable. The influence of the set error of the rotor resistance is discussed and the design criterion for the feedback gain of the observer is presented. Finally, the system is linearized for the parameter design of the speed estimator.     

A wide constant power range vector-controlled AC motor drive usingwinding changeover technique

A high-performance vector-controlled induction motor drive with a very wide constant power range of 1:10 to 1:30 has been developed and widely accepted in the spindle drives of machine tools. The motor has two combinations of winding connections, and one of them is selected in accordance with the operating conditions. The versatility of the winding changeover technique has been introduced and demonstrated. A wide constant power range is achieved, and the gear box used in a conventional machine is eliminated. In addition, it was proved by actual operations that the machining operation can be continued during the changeover without sacrificing the quality of the final product. The basic idea, features, and test results of this technique are described     

A stator-flux-oriented vector-controlled induction motor drive withspace-vector PWM and flux-vector synthesis by neural networks

A stator-flux-oriented vector-controlled induction motor drive is described where the space-vector pulsewidth modulation (SVM) and stator-flux-vector estimation are implemented by artificial neural networks (ANNs). ANNs, when implemented by dedicated hardware application-specific integrated circuit chips, provide extreme simplification and fast execution for control and feedback signal processing functions in high-performance AC drives. In the proposed project, a feedforward ANN-based SVM, operating at 20 kHz sampling frequency, generates symmetrical pulsewidth modulation (PWM) pulses in both undermodulation and overmodulation regions covering the range from DC (zero frequency) up to square-wave mode at 60 Hz. In addition, a programmable cascaded low-pass filter (PCLPF), that permits DC offset-free stator-flux-vector synthesis at very low frequency using the voltage model, has been implemented by a hybrid neural network which consists of a recurrent neural network (RNN) and a feedforward neural network (FFANN). The RNN-FFANN-based flux estimation is simple, permits faster implementation, and gives superior transient performance when compared with a standard digital-signal-processor-based PCLPF. A 5 HP open-loop volts/Hz-controlled drive incorporating the proposed ANN-based SVM and RNN-FFANN-based flux estimator was initially evaluated in the frequency range of 1.0-58 Hz to validate the performance of SVM and the flux estimator. Next, the complete 5 HP drive with stator-flux-oriented vector control was evaluated extensively using the PWM modulator and flux estimator     

A high-speed vector-controlled spindle motor drive with closedtransition between with encoder control and without encoder control

A 40000-r/min vector-controlled induction motor drive is introduced. The vector control of induction motors has been widely accepted in spindle drives of machine tools where they replace conventional DC motors because of the low maintenance requirements. Another important feature of the AC spindle drive is its high-speed capability. The magnetic encoder is most widely used as the speed detector because it is suited for use in an adverse environment. However, the magnetic encoder with high resolution and a high S/N ratio loses the output pulses at extremely high speed. In the drive system introduced, the conventional vector control is used in the low-speed range, and the vector control without the encoder is used in the high-speed range. Close transition between two modes is made without interrupting the operation     

Parameter identification of vector-controlled induction machines

Contents This paper describes the identification of electromagnetic time constants and stator resistance for field oriented induction motor drives. The model of an induction motor at standstill in terms of state representation is discussed. A direct continuous-time identification from the standstill time-domain test data is based on the parametrized observer state vector. In a laboratory configuration the stator resistance is influenced by the non-linear inverter gain function. Two categories of current responses to voltage steps and to pseudo random binary sequences are examined. The current transients indicate saturation effects. Parameter estimates of a linear machine model are determined using least squares algorithms. Simulation and experimental studies are carried out in a Matlab software environment. Corresponding results obtained for two induction motor drives of different power ratings are included.

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Parameteridentifikation von vektorgeregelten Asynchronmotoren

Übersicht Der Aufsatz beschreibt die Identifikation der elektromagnetischen Zeitkonstanten und des Statorwiderstandes für Antriebe mit vektorgeregelten Asynchronmotoren. Das Modell eines Asynchronmotors im Stillstand wird in der Zustandsform beschrieben. Die direkte zeitkontinuierliche Identifikation aus den Meßdaten im Stillstand beruht auf dem parametrierten Beobachter Zustandsvektor. In einer Laboranordnung wird der Statorwiderstand durch die nichtlineare Kennlinie des Umrichters beeinflußt. Es werden zwei Kategorien der Stromantwort auf Spannungssprünge und PRBS-Sequenzen untersucht. Der transiente Stromverlauf weist Sättigungseffekte auf. Parameterschätzungen an einem linearen Maschinenmodell werden mittels der Methode der kleinsten Fehlerquadrate bestimmt. Es werden Simulationsrechnungen und experimentelle Studien in einer Matlab Umgebung durchgeführt. Die Ergebnisse für zwei Antriebe mit Asynchronmotoren unterschiedlicher Leistung werden vorgestellt.

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This work was supported in part by the Deutscher Akademischer Austauschdients, Ref. 323, and by a grant from the State Committee for Science Research (Poland) Contract BW959050.     

Performance analysis of a speed-sensorless induction motor drive based on a constant-switching-frequency DTC scheme

A control technique, which utilizes the stator flux components as control variables, has been applied to a speed-sensorless induction motor drive. The scheme may be regarded as a development of a direct torque control scheme, aimed at achieving a constant-switching-frequency operation. At each sampling period the required voltage vector is calculated on the basis of the error between the reference and the estimated stator flux vector. The problems related to the voltage-source inverter dead time and the stator flux estimation at low speed have been analyzed, and an efficient solution has been proposed. The performance of the drive system has been verified by experimental tests, and good results have been achieved in both steady-state and transient operating conditions.     

嵌入式永磁同步电机自适应在线参数辨识

针对嵌入式永磁同步电机参数辨识问题,提出一种自适应在线参数辨识方法,可在同一模型中对定子电阻、d轴电感、q轴电感和永磁体磁链进行辨识.该方法基于模型参考自适应系统,在同步旋转d-q坐标系下,构造出q轴电流自适应观测器,利用q轴电流观测误差,借助Lyapunov超稳定理论建立参数的辨识模型并推导出待辨识参数的自适应律,保证了特定条件下系统的稳定性和辨识参数的收敛性,解决了参数在线辨识算法的鲁棒性差、算法复杂等问题.仿真和实验结果表明,辨识参数能够在较短的时间内收敛到真实值附近,并且具有较小的误差.     

Fast efficiency optimization techniques for the indirect vector-controlled induction motor drives

This paper presents two simple and very useful techniques for the efficiency optimization of the indirect vector-controlled induction motor drives. In the synchronously rotating reference frame the flux-producing current is controlled until the power at the DC link is minimum. Of the two techniques, the first method controls the flux-producing current in a regular and smooth manner. The second technique combines loss model and search approaches in a unique way to propose a hybrid method, where the first estimate is from the loss model approach and the subsequent adjustment of the flux is through the search technique. Both the algorithms are simple, easily realizable, and offer fast convergence. Also, smooth control of the flux offers excellent dynamic performance. A comparative assessment shows that the hybrid method is the best, even if an approximate equivalent circuit for the induction motor is used for the analysis and optimization of the losses. The close agreement between the simulation and the experimental results confirms the validity and usefulness of the proposed techniques.     

感应电动机变频调速矢量控制系统的研究

采用双８０ｃ１９６ＫＣ单片机作为控制单元,构成全数字化变频调速矢量控制系统。双单片机之间数据的快速并行通讯由双口ＲＡＭ ＩＤＴ７１３０来完成。系统的电流调节器采用两个电流滞环调节器,而转速调节器采用ｂａｎｇ－ｂａｎｇ控制与ＰＩ控制相结合的双横控制方式。实验结果表明,系统的硬件和软件设计合理,调速性能优良。     

Optimum control scheme for the maximum efficiency drive of linear synchronous motor used for ropeless elevator

Our research group at Musashi Institute of Technology is currently concentrating on the improvement of the overall efficiency for driving ropeless elevators using a linear synchronous motor (LSM). Since these elevators are ropeless, counterweights cannot be installed in the system. Therefore, the linear motors must develop a higher thrust force. In addition to the improvement of the efficiency of LSM it is also necessary to develop a high‐efficiency drive control method. Our laboratory is involved in studies on efficiency improvement. In order to design an efficient control system, we believe it is necessary to understand changes of efficiency caused by variations of driving conditions, such as load mass, velocity, and required thrust force. The dynamic control method changing the operating point to achieve the maximum power is known as maximum power point tracking (MPPT). This approach is useful and can be applied to the control of LSM for ropeless elevators. The car cage of a ropeless elevator periodically repeats acceleration and deceleration cycles in the process of ascent and descent motions. The optimum‐minimum‐energy consumption is obtained if the system is always operated at the maximum efficiency, even if the drive conditions change. In this paper, we first discuss the basic characteristics of LSM for ropeless elevators. Then, based on these characteristics, we derive the maximum efficiency loci as a unique combination of a current and a power angle for a specific condition. We also provide a design of the MPPT controller of LSM and analyze results of simulation of driving the LSM using MPPT. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(3): 70–78, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20061