High‐performance speed control based on an instantaneous speed observer considering the characteristics of a dc chopper in a low speed range

This paper proposes a new high‐performance speed control method for wide speed range, which is based on instantaneous speed observer considering the characteristics of dc chopper. In order to regulate a motor speed for wide speed reference including a very low speed range, this paper designs the instantaneous speed observer which uses the information of an armature current and an armature voltage. This observer has no effect of inertia variation and disturbance torque completely, but it has the effect of electrical parameter variation. Hence, this paper proposes a new identification algorithm to cancel out the estimation error caused by both the resistance variation and the voltage drop. The proposed observer can always estimate an instantaneous value of motor speed. The proposed total system becomes a new robust speed servo system for a wide speed range. © 1999 Scripta Technica, Electr Eng Jpn, 130(3): 77–87, 2000     

Current sensorless speed servo system of a PM motor based on the current estimation method

This paper proposes a new speed servo system for a PM motor without a current sensor, which is constructed by the current simulator of a PM motor. The proposed speed servo system is simple and economical. The sensor of the proposed system is only a position sensor used as an encoder. Hence, the proposed speed servo system has little influence on the switching noise of a PWM inverter. Moreover, the resolution of the proposed current simulator can be higher than that of the conventional actual feedback system. In this paper, the experimental results point out that the proposed current sensorless speed servo system has the desired current and speed response. The current waveform of the proposed system is smooth and clean. Moreover, this paper proposes a new identification algorithm for motor resistance R_a and main flux Φ_fa by using only a position sensor. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(3): 64–73, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10084     

Anti‐windup algorithm with priority to proportional control output of speed PI controller for precision servo system

A robust servo system is important for performance improvement of motion control systems in several industry applications. Generally, a high‐speed positioning servo system consists of robust control systems with integrator, such as PI controller. The industrial servo system always has the limitation for the capacity of the actuator and power amplifier. An ordinary industrial position servo system often has to deal with the saturation of motor current and motor speed. It is difficult for the high‐speed positioning servo system to keep the robust position control against the saturation of motor current and motor speed. This is the case because an ordinary position servo system has a complicated control structure with many control loops. Hence, it sometimes has a large overshoot and an oscillated response due to the limitation of motor current and motor speed. In order to overcome this problem, this paper proposes a new robust high‐speed positioning servo system considering the saturation of torque current and motor speed. The experimental results show that the proposed robust high‐speed positioning servo system has quick and stable position response for the saturation of motor current and motor speed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(3): 57–64, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20904     

Performance improvement of induction motor speed sensor‐less vector control system using an adaptive observer with an estimated flux feedback in low‐speed range

Because of various errors caused by the dead time of an inverter, temperature variation of resistances, and so on, speed estimation error is inevitable in speed sensor‐less vector control of an induction motor. In particular, the speed control loop becomes unstable at near‐zero frequencies. In order to solve these problems, this paper proposes a novel design of an adaptive observer for speed estimation. By adding a feedback loop of the error between the estimated flux and the flux command, the sensitivity of speed estimation and primary resistance identification is improved. The proposed system is analyzed and appropriate feedback gains are derived. Experimental results showed good performance in the low‐speed range. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(3): 33–46, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20909     

Inertia identification for the speed observer of the low speedcontrol of induction machines

This paper presents a control method for induction machines in a low speed range with an instantaneous speed observer and inertia identification. When a low resolution incremental-type encoder is used for the speed detection, only the average speed in the interval of the encoder pulses is observed, and it usually makes the speed controller unstable at the very low speed range. This paper, therefore, proposes a low speed control method with a speed observer which is implemented by the disturbance observer using a low precision shaft encoder. Furthermore, to improve the performance of the speed controller, the authors perform the identification of the inertia which is estimated by the periodic test signal. They show that this proposed method is superior to the conventional method by comparing simulation and experimental results     

Inertia moment identification in the average speed-type instantaneous speed observer

In recent servomotor control systems using highspeed microprocessors, it is difficult to obtain accurate speed information by using a low-resolution shaft encoder because encoder pulses are very sparse in the low-speed range. To overcome this problem, the instantaneous speed observer is proposed, system stability is improved, and strong disturbance rejection control is realized. However, when the inertia moment changes, the estimated instantaneous speed has error because the observer uses the nominal value of the inertia moment to calculate the instantaneous speed. For this reason, the identification method of the inertia moment for the “position input-type” speed observer is proposed but it operated at about 50 rpm speed command. This paper proposes some novel identification methods for the “average speed-input type” instantaneous speed observer and identifies the inertia moment in the very low speed range below 1 rpm.     

Sensorless vector control of induction motor stabilized in the whole region with speed and stator resistance identification based on augmented error

This paper proposes new identification laws of an adaptive flux observer for speed sensorless vector controls. In speed sensorless vector controls of an induction motor with the adaptive observer, the speed identification system is known to be unstable in a part of the regenerating region. In addition, it is pointed out that the stator resistance variation interferes with the speed identification. Thus, it is necessary to find an adaptive scheme which can stabilize the identification system. In this paper, first, the stability on the parameter identification is discussed from the viewpoint of Popov's hyperstability. Second, identification laws for the speed and the stator resistance are proposed based on the new identification system which is derived by using the augmented error. Finally, the effectiveness of the proposed method is shown by experiments. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 52–63, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20187     

Position and speed sensorless control for IPMSM based on estimation of position error

In most variable‐speed drives of PMSM, some type of shaft sensor such as an optical encoder or resolver is connected to the rotor shaft. However, such sensor presents several disadvantages such as drive cost, machine size, reliability, and noise immunity. Therefore, the sensorless control of PMSM is desired and various sensorless control strategies have been investigated. This paper presents a novel sensorless control strategy for an interior permanent magnet synchronous motor (IPMSM). A new model of IPMSM using an extended electromotive force (EMF) in the rotating reference frame is utilized in order to estimate both position and speed. The extended EMF is estimated by the least‐order observer, and the estimation position error is directly obtained. The proposed scheme corrects the estimated position and speed so that the estimation position error becomes zero. The proposed system is very simple and the design of the controller is easy. Several drive tests are carried out and the experimental results show the effectiveness of the proposed sensorless control system. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(2): 43–52, 2003; Published online in Wiley InterScience ( www. interscience.wiley.com ). DOI 10.1002/eej.10180     

A new variable‐speed,constant‐frequency,stand‐alone power generating system

Variable‐speed and constant‐frequency power generating systems using rotor excitation of the wound‐rotor induction machines have been used for such applications as variable‐speed pump generators and flywheel energy storage systems. However, the stand‐alone generating system of this type has only been reported and has not yet been practically used. On the other hand, the stand‐alone generating systems using diesel engines have been widely used for emergency supplies of plants or isolated islands and so on. However, in these cases, synchronous generators are usually used. If the output frequency is to be kept constant, there is the need to control the speed of the engine using a high‐performance governor. Even then, the output frequency changes in the case of a sudden load change. This paper proposes a new stand‐alone power generating system. In this system, the constant‐frequency output voltage can be obtained even though rotor speed changes by several percent. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(2): 75–85, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10191     

Simulation of variable‐speed wind generation system using boost converter of permanent magnet synchronous generator

This paper proposes a variable‐speed wind generation system using the boost converter. The proposed system has three speed control modes for the wind velocity. The control mode of low wind velocity regulates the armature current of the generator with the boost converter to control the speed of wind turbine. The control mode of middle wind velocity regulates the DC link voltage with the vector controlled inverter to control the speed of wind turbine. The control mode of high wind velocity regulates the pitch angle of the wind turbine with the pitch angle control system to control the speed of the wind turbine. The hybrid combination of three control modes extends the variable‐speed range. The proposed system simplifies maintenance, improves reliability, and reduces the costs compared with the variable‐speed wind generation system using a PWM converter. This paper describes the control strategy and modeling for a simulation of the proposed system using Simulink of Matlab. It also describes the control strategy and modeling of a variable‐speed wind generation system using a PWM converter. The steady state and transient responses for wind velocity changes are simulated using Matlab Simulink. This paper verifies the fundamental performance of the system using a boost converter by discussing the simulation results of both systems. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 37–54, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20902     

Permanent magnet synchronous motor torque control by gain‐scheduled feedback with state resets

In this paper, we address the torque control problem of a permanent magnet synchronous motor (PMSM) under input voltage limitation. First, a plant model of a PMSM is derived as a linear parameter varying system in which the rotor speed is included as the varying parameter. Second, we show that setpoint tracking control is achievable under the time variation of the rotor speed. Then we show a method of constructing a control law that achieves convergence of the motor torque to a step reference signal under input voltage limitation and time variation of the rotor speed. The proposed control law consists of a gain‐scheduled control law and a servo compensator. In the proposed control method, the scheduling parameter and the controller state are optimally updated so that the transient response is improved. The effectiveness of the method is shown by a numerical example. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A servo system of AC motor based on voltage modulation fitting for FPGA and consideration of voltage saturation

This paper proposes a space voltage vector modulation (SVM) method for a speed servo system to obtain a quick current response. The proposed SVM method shortens the control lag time of the conventional SVM inverter. In addition, this proposed method is easily implemented in hardware using an FPGA (Field Programmable Gate Array) because the proposed SVM equations are transformed into expressions that hardly need multiplication. By using the proposed SVM method, the servo system realizes quick and stable current control with wide bandwidth. Moreover, by using PI controllers considering the voltage saturation and the torque limiter to the speed servo system, the servo system carries out stable speed control on voltage saturation. Both the proposed SVM method and the PI controllers considering voltage saturation are applied to the speed servo system of a vector controlled induction motor. The effectiveness of both the proposed SVM method and the PI controllers considering voltage saturation is verified by the experimental results. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 60–68, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20989     

A new generalized high‐frequency voltage injection method and mirror‐phase estimation method for sensorless drive of salient‐pole PMSMSs

This paper proposes a new generalized high‐frequency voltage injection method for sensorless drive of salient‐pole permanent‐magnet synchronous motors. The injected high‐frequency voltage has a unique spatially‐rotating elliptical shape, with the amplitudes of both the major and minor axes varying with the motor speed, and can be designed by selecting a design parameter. The high‐frequency current caused by the injected voltage, which has information on the rotor phase to be estimated, is speed‐independent, that is, is not affected by the motor speed at all. Consequently, the rotor phase can be estimated in a wide speed range from zero to the rated speed. By selection of the design parameter, the properties of the high‐frequency current can be adjusted appropriately to the associated motor‐drive system consisting of a motor and an inverter. As a versatile phase estimation method for estimating rotor phase using the high‐frequency current, the “mirror‐phase estimation method” is reconstructed and reproposed. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(3): 67–82, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20803     

Robust speed estimation and control of an induction motor drive based on artificial neural networks

In this paper, a speed estimation and control scheme of an induction motor drive based on an indirect field‐oriented control is presented. On one hand, a rotor speed estimator based on an artificial neural network is proposed, and on the other hand, a control strategy based on the sliding‐mode controller type is proposed. The stability analysis of the presented control scheme under parameter uncertainties and load disturbances is provided using the Lyapunov stability theory. Finally, simulated results show that the presented controller with the proposed observer provides high‐performance dynamic characteristics and that this scheme is robust with respect to plant parameter variations and external load disturbances. Copyright © 2007 John Wiley & Sons, Ltd.     

A study on higher‐order disturbance observer and robust stability

In earlier papers, it has been reported that a fast and precise servo system, which has low sensitivity to parameter variation and disturbance, can be realized with simple structure by using a high‐order disturbance observer. However, no clear and simple design method satisfying specifications for robust stability, the influence of measurement noise, and relative stability (damping characteristics) for large parameter variation has been proposed. In this paper, we clarify the class of robust servo systems realized by adjusting the order of the disturbance observer and the control parameters. We apply this strategy to the design of a second delay system, such as a position servo system, and realize a high‐performance robust servo system using a high‐order disturbance observer. © 1999 Scripta Technica, Electr Eng Jpn, 128(1): 37–44, 1999     

一种用于异步电机控制的新型滑模速度观测器研究

提出了一种新颖的用于异步电机控制的滑模速度观测器。该观测器具有结构简单、新颖、易于实现的特点,在无速度传感器的电机控制系统中,能有效地消除运用滑模观测器所固有的高频速度抖动现象。该观测器利用电压和电流信号构成观测器估计电机转速、转子磁通量以及转子磁通的位置,其理论的正确性可由李雅普诺夫理论证明。将其应用于采用磁场定向矢量控制方法的无速度传感器的感应电机控制系统,实验证明,在整个调速范围内都取得了很好的效果,系统具有很好的稳态精度和动态响应性能。     

一种用于异步电机控制的新型滑模速度观测器研究

提出了一种新颖的用于异步电机控制的滑模速度观测器。该观测器具有结构简单、新颖、易于实现的特点，在无速度传感器的电机控制系统中，能有效地消除运用滑模观测器所固有的高频速度抖动现象。该观测器利用电压和电流信号构成观测器估计电机转速、转子磁通量以及转子磁通的位置，其理论的正确性可由李雅普诺夫理论证明。将其应用于采用磁场定向矢量控制方法的无速度传感器的感应电机控制系统，实验证明，在整个调速范围内都取得了很好的效果，系统具有很好的稳态精度和动态响应性能。     

A sensorless drive system for brushless DC motors using a digital phase‐locked loop

This paper proposes a sensorless drive system for Brushless DC (BLDC) motors using a Digital Phase‐Locked Loop (DPLL). The Back Electromotive Force (BEMF) voltage is measured from the motor winding to determine the permanent magnet rotor position using the DPLL, and Pulse Width Modulation (PWM) limits the motor current to control the speed of BLDC motors. The proposed method can drive BLDC motors using an open‐loop control without stepping out. Also, the proposed method is compared experimentally with a control method that uses Hall sensors. Experimental results for the BLDC motor show the effectiveness of the proposed method. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(1): 57–66, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10074     

A new position‐sensorless position control method for high‐speed spindle systems

This paper proposes a new position‐sensorless position control method for high‐speed spindle drive systems. Mechanical vulnerability of position sensors such as an encoder mounted on a spindle motor is becoming a serious problem as required speed increases. For high speeds above 1500 rad/s, sensorless drive is preferred. It is possible for current technologies to control spindle motor in speed control mode without the sensor, but not in position control mode without the sensor. In the example of high‐speed spindle systems of automatic machine tools, implements must be automatically attached to and removed from the spindle at standstill. Automation necessitates position control, for which current technologies require a sensor. The proposed method makes it possible to realize pure sensorless high‐speed spindle systems performing in both speed and a position control modes. The method can attain a position control performance with quick settling from speed control and a repetitive positioning precision of 0.006 rad, 0.4°, which is comparable to that achieved by current sensor‐based methods. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 58–69, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10059     

Achievement method of high‐speed response of error prediction tracking control for optical disk system

This paper proposes the new design method of error‐prediction control systems combining the ZPET control and the robust feedback control. The error‐prediction control system based on ZPET control can reduce the tracking error caused by periodic disturbances more efficiently than the conventional repetitive control technique. However, the proposed tracking servo system does not reduce the residual tracking error caused by the low‐pass filter of the feedforward compensation and by the long sampling time. In order to overcome this problem, this paper proposes the new structure of the feedforward tracking control system. The modified ZPET control tracking servo system for optical disk recording system does not include the low‐pass filter and its sampling time becomes faster. On the other hand, the sudden disturbance observer reduces the influence of nonperiodic disturbances. The experimental results point out that the proposed tracking servo system has a precise tracking response against both the periodic disturbances and the nonperiodic disturbances. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 51–59, 2010; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20800