Sensorless PM brushless DC motor drives

To control PM brushless DC motors, position and speed sensors are indispensable because the current should be controlled depending on the rotor position. However, these sensors are undesirable from standpoints of size, cost, maintenance, and reliability. There are different ways of approaching this problem, depending on the flux distribution. The paper presents the speed and position sensorless control of PM brushless DC motors with a sinusoidal flux distribution. Two approaches are presented and compared with each other; one is based on the voltage model of the motor and another is based on the current model. The starting procedure is also a very difficult problem under sensorless drives, because the sensorless drive algorithm uses voltage and current for estimation of rotor position, but no information is available before starting. A novel starting method is presented by using a salient-pole machine. Experimental results based on DSP-TMS320C25 controller are shown for comparisons, which demonstrate desired characteristics both in steady-state and starting conditions     

Sensorless torque control of SyncRel motor drives

This paper describes a direct self-control (DSC) scheme for synchronous reluctance motor drives. The presented DSC scheme develops a new torque control methodology that does not require any position transducer to synchronize the stator current vector with the rotor. Such a control strategy differs from the conventional DSC approach in order to fit some specific requirements of synchronous reluctance (SyncRel) machines. First, torque and rotor position are controlled instead of torque and stator flux as in a conventional DSC scheme. Second, the operating sector is selected according to the actual position of the current vector rather than the position of the stator flux. The proposed methodology allows simplifying implementation of the torque control on SyncRel drives and reducing the global cost for medium-performance electric drives. Simulations and experimental tests on a 1.5-kW motor drive are provided to evaluate the consistency and the performance of the proposed control technique     

Sensorless position control of a brushless motor in circulatory assist devices

An innovative technique to implement position feedback and commutation of brushless D.C. motors without explicit position sensing is presented. The procedure has been successfully implemented for the Pennsylvania State University Electric Ventricular Assist Device (EVAD). Laboratory tests indicate that the method is successful for pumping operations in a mock circulatory loop for beat rates up to 60 beats min⁻¹ and over several days of uninterrupted operation. This method of sensorless commutation is presently being investigated for inclusion as a backup system for the Penn State circulatory assist devices.     

Fuzzy adaptive vector control of induction motor drives

This paper deals with the design and experimental realization of a model reference adaptive control (MRAC) system for the speed control of indirect field-oriented (IFO) induction motor drives based on using fuzzy laws for the adaptive process and a neuro-fuzzy procedure to optimize the fuzzy rules. Variation of the rotor time constant is also accounted for by performing a fuzzy fusion of three simple compensation strategies. A performance comparison between the new controller and a conventional MRAC control scheme is carried out by extensive simulations confirming the superiority of the proposed fuzzy adaptive regulator. A prototype based on an induction motor drive has been assembled and used to practically verify the features of the proposed control strategy     

工业应用的无传感器电动机传动

最近几年,工业界和学术界均致力于无传感器交流电动机传动的研发,使其动态性能特征与轴上机械传感器的电动机传动可比拟或相近。一些研发成果已被工业采用并投放市场。本文介绍欧洲的发展现状和不同解决方案被电动机传动制造商接受或拒绝的原因。     

Sensorless control of ultrahigh-speed PM brushless motor using PLL and third harmonic back EMF

Application-specific integrated circuit (ASIC) ML4425 is often used for sensorless control of permanent-magnet (PM) brushless direct current (BLDC) motor drives. It integrates the terminal voltage of the unenergized winding that contains the back electromotive force (EMF) information and uses a phase-locked loop (PLL) to determine the proper commutation sequence for the BLDC motor. However, even without pulsewidth modulation, the terminal voltage is distorted by voltage pulses due to the freewheel diode conduction. The pulses, which appear very wide in an ultrahigh-speed (120 kr/min) drive, are also integrated by the ASIC. Consequently, the motor commutation is significantly retarded, and the drive performance is deteriorated. In this paper, it is proposed that the ASIC should integrate the third harmonic back EMF instead of the terminal voltage, such that the commutation retarding is largely reduced and the motor performance is improved. Basic principle and implementation of the new ASIC-based sensorless controller will be presented, and experimental results will be given to verify the control strategy. On the other hand, phase delay in the motor currents arises due to the influence of winding inductance, reducing the drive performance. Therefore, a novel circuit with discrete components is proposed. It also uses the integration of third harmonic back EMF and the PLL technique and provides controllable advanced commutation to the BLDC motor.     

Optimal vector control of pumping and ventilation induction motor drives

An original speed control for centrifugal pump and fan drives with squirrel-cage induction motors that seeks the maximum energy saving is proposed. The strategy is based on minimizing the motor and converter losses at the steady state and minimizing the transient time that the motor employs in passing from one steady stage to another. The shortest transient time is achieved by applying the Pontriagin's maximum principle taking into account the parabolic load torque-speed dependence of these types of drives. Short-time transients, which take the motor from one point of maximum efficiency to another, contribute to reduce losses and to extend the application of the energy-saving concept to the drives with frequent changes of load torque and speed.     

Adaptive speed control for induction motor drives using neuralnetworks

In this paper, the adaptive speed control of induction motor drives using neural networks is presented. To obtain good tracking and regulating control characteristics, a digital two-degree-of-freedom (2DOF) controller is adopted and a design procedure is developed for systematically finding its parameters according to prescribed specifications. The parameters of the controller corresponding to various drive parameter sets are found off-line and used as the training patterns to estimate the connection weights of neural networks, Under normal operation, the true drive parameters are real-time identified and they are converted into the controller parameters through multilayer forward computation by neural networks. The parameters of the 2DOF controller can be adapted to match the desired specifications under various operating conditions     

内模PID控制器在无刷直流电机调速系统中的应用

针对无刷直流电机中传统PID控制器参数调节复杂、对环境适应能力较弱等问题,在分析内模控制与经典PID控制的内部对应关系的基础上,综合其优点,设计采用了一种基于内部模型的PID控制器（简称IMC-PID）对无刷直流电机进行调速。在建立对象理论模型的基础上,通过对控制器在线仿真比较表明：针对本设计对象,基于内部模型的PID控制器不论在系统阶跃响应或是扰动跟踪等控制效果上都能到达经典PID控制的要求,同时还降低了参数设计的复杂性和随机性。     

Sensorless speed control of nonsalient permanent-magnet synchronous motor using rotor-position-tracking PI controller

This paper presents a new velocity estimation strategy of a nonsalient permanent-magnet synchronous motor (PMSM) drive without a high-frequency signal injection or special pulsewidth-modulation (PWM) pattern. This approach is based on the d-axis current regulator output voltage of the drive system that has the information of rotor position error. Rotor velocity can be estimated through a rotor-position-tracking proportional-integral (PI) controller that controls the position error to zero. For zero and low-speed operation, the PI controller gains of rotor position tracking controller have a variable structure according to the estimated rotor velocity. In order to boost the bandwidth of the PI controller around zero speed, a loop recovery technique is applied to the control system. The proposed method only requires the flux linkage of the permanent magnet and is insensitive to parameter estimation error and variation. The designers can easily determine the possible operating range with a desired bandwidth and perform vector control even at low speeds. The experimental results show the satisfactory operation of the proposed sensorless algorithm under rated load conditions.     

Improved direct torque and flux vector control of PWM inverter-fedinduction motor drives

In this paper, a direct torque and stator flux vector control system is presented. The principle of this method was proposed by Takahashi and Noguchi in 1985. In contrast to the field oriented control, no coordinate transformation and current control loop is required. In practical application, however, problems occur with starting and operation in the zero speed region. This paper shows how, by introducing an additional carrier signal to the torque controller input, a robust start and improved operation in the low speed region can be achieved. The simulation and experimental results which illustrate the performances of the proposed system are presented. Also, nomograms for controller design are given     

基于模糊自适应PI的无刷直流电机调速系统研究

针对采用传统PI控制算法的无刷直流电机(BLDCM)调速系统存在精度低、抗干扰能力弱等问题,提出一种基于初始比例值优化的模糊自适应PI控制算法。建立BLDCM转速、电流双闭环调速系统数学模型,对其转速环进行模糊自适应PI控制,并提出一种初始比例值优化的方法。应用Matlab/Simulink进行系统设计和仿真,对比传统PI、普通模糊自适应PI和优化后模糊自适应PI三种控制算法的仿真结果。结果表明,优化后的模糊自适应PI控制算法使BLDCM调速系统具有更好的动态性能,达到了较好的控制效果。     

An enhanced Z-source inverter topology-based permanent magnet brushless DC motor drive speed control

In this paper, an enhanced Z-source inverter (ZSI) is introduced for controlling the speed of permanent magnet brushless DC motor (PMBLDCM) drive. It is the extension of the conventional ZSI and the elements used in the circuit are the same as those of the conventional ZSI, except that the position of Inverter Bridge and diode would be exchanged from the classical circuit diagram. This exchanged circuit avoids the startup path of the inrush current and hence reduces the inrush current and improves the motor efficiency. Different modes of enhanced ZSI are studied with PMBLDCM. The voltage polarity of Z-source capacitors in the proposed circuit is the same as that of the input voltage polarity. Furthermore, to get the same voltage boost, the capacitor voltage stress is reduced to a significant extent. The speed control capability of the proposed brushless DC motor drive is compared with that of the conventional ZSI. The proposed ZSI is implemented in MATLAB/Simulink working platform and the output performance is evaluated. Also, the performance of voltage ratio is analysed both by simulation and mathematical models. All these analyses are known to express the innovative features of the proposed system.     

Quick-response torque-controlled induction motor drives usingphase-locked loop speed control with disturbance compensation

This paper presents an excellent speed control scheme for induction motor drives. Phase-locked loop (PLL) techniques based on proportional-integral derivative (PID) feedback of the phase difference is employed to provide extremely accurate speed regulation. The quick-response torque control of an induction motor is used to provide better torque characteristics. In addition, a disturbance is estimated by a disturbance observer and the estimated value is fed back to eliminate the disturbance effect on the motor speed. The proposed system combines the precise speed regulation of PLL technique and the advantage of the quick-response torque control, with the insensitivity to disturbance by the disturbance compensation. A phase-plane analysis is used to evaluate the effects of gain coefficients of PID feedback of phase difference. Experimental results are presented to verify the characteristics of the proposed system     

Fuzzy two-degrees-of-freedom speed controller for motor drives

A fuzzy two-degrees-of-freedom (2-DOF) controller and its application to the speed control of an induction motor drive are presented in this paper. The proposed controller is composed of two fuzzy controllers to obtain good tracking and regulating responses. Unlike the conventional fuzzy controller, the error between the outputs of a reference model and the controlled drive is used to drive the proposed fuzzy controller. The drive rotor speed response can closely follow the trajectory produced by the reference model, and good load speed regulating response can also be obtained simultaneously owing to the possession of two-degrees-of-freedom in structure. Moreover, these performances are rather insensitive to the operating condition changes. The dynamic signal analysis as well as the construction of fuzzy control algorithms are described in detail. Some simulated and measured results are provided to demonstrate the effectiveness of the proposed fuzzy controller     

Variable structure current control for induction motor drives byspace voltage vector PWM

In this paper, a variable structure current controller based on a space voltage vector PWM scheme is presented for induction motor drives. In this current controller design, only the current sensors are employed and we attempt to force the stator currents to be exactly equal to the reference currents rapidly. This proposed current controller, which is based on the space voltage vector PWM drive, exhibits several advantages in terms of reduced switching frequency, robustness to parameter variations, elimination of current/torque ripple, and improved performance in induction motor drive. It shows that the current control laws can be demonstrated in theory. Finally, simulation and experimentation results verify the proposed control scheme     

飞轮电机速度的无传感器控制方法

简述了飞轮电机的无传感器控制的基本原理,分类介绍了假定旋转坐标法、模型参考自适应系统、观测器、扩展的卡尔曼滤波、滑模观测器、高频信号注入法等各种用于飞轮电机速度无传感器控制的方法、效果及研究应用状况.由控制效果可见,用无传感器控制可以使飞轮电机的整体性能得到显著改善,是高性能飞轮电机调速系统开发的一个重要方向.