Design Method for Improving Motor Efficiency of Switched Reluctance Motor

The motor efficiencies of switched reluctance motors (SRMs) are inferior to those of permanent magnet synchronous motors. This paper describes a design procedure for an SRM to obtain a higher motor efficiency. The first step in the design procedure makes clear the principle for improving the motor efficiency. The cross‐sectional and axial shapes of the rotor and stator cores are designed by magnetic field analysis with the two‐dimensional (2D) and 3D finite element method. A high‐efficiency SRM with 12 stator poles and eight rotor poles is designed. The designed SRM was produced experimentally, and was tested to verify its performance. The motor efficiency was improved in comparison to the standard SRM with six stator poles and four rotor poles.     

双永磁电机系统转速同步控制

针对双永磁同步电机系统中,由于负载扰动造成双电机转速不同步而极易引发差速振荡的问题,该文结合交叉耦合控制结构和滑模控制算法,提出一种基于积分型滑模速度控制器的转速同步控制策略,使用指数趋近律以及饱和函数抑制滑模固有的抖振现象。此外,设计了转速同步控制器对两电机的电流环进行补偿,通过选择合适的耦合同步系数,使两电机速度尽快达到同步。实验结果验证了在所提出的控制策略下,双永磁同步电机系统的鲁棒性、转速跟踪性能以及同步性能均得到提升。     

Experimental verification for stability improvement of sensorless vector control system of induction motor using real‐time tuning of observer gain

This paper proposes a method for the design of the adaptive rotor flux observer gain to improve stability at low speed and in regenerating mode. The method is based on stability analysis, which utilizes a linearized model considering all systems, including each control loop. Therefore, the proposed method considers the effects of motor constants and control circuit constants. The stability analysis using the transfer function for the rotor speed considers the arrangement of poles and zeros and the steady‐state error. The rotor flux observer gain which improves the stability for each operating condition is ascertained. This paper also proposes a real‐time tuning method for the observer gain. The validity of the proposed method was confirmed by simulation using Matlab Simulink and by experiment. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(1): 67–81, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20715     

直线电机位置伺服系统的增强复合非线性控制

针对高性能机电系统中常用的直线伺服电机,设计了一个能实现快速与准确的定点运动的位置控制器。控制器采用线性控制律与平滑非线性控制律相结合的方案,并利用一个降阶线性状态观测器对电机运动速度(未量测)加以估计。为了消除未知扰动带来的稳态误差,控制律中嵌入了积分控制作用。整个控制律采用全参数化设计,可实现动态增益控制,方便了在线参数整定与性能优化。控制方案应用于一个实际的永磁直线电机位置伺服系统,基于TMS320F28335 DSC进行了试验测试,结果表明系统能对各目标位置进行准确的跟踪,且具有理想的瞬态性能。     

A generalized method of controlled voltage source-fed induction motor vector control using the observer theory

Vector control of induction motors is widely used for industrial applications. On-line parameter identification and speed sensorless control are being studied actively. A representative method for these problems is the application of an adaptive full-order observer. The rotor flux for vector control is estimated by a full-order observer and machine parameters, or the rotor speed is determined by an adaptive algorithm. In this paper, a new vector control scheme with parameter identification is proposed. This method is based on the adaptive full-order observer. However, the observed currents which are usually estimated in the voltage model are considered as command currents and the voltage model is used for the current controller. As a result, the proposed system is simpler than the conventional adaptive full-order observer system. Since the proposed system is composed of an induction motor model in a synchronously rotating reference frame, the well-known slip frequency control block is contained. The arrangement of the poles which are related to the torque transfer function is discussed. A linear model is derived taking into account the effects of the change of the stator and rotor resistances. The trajectories of poles and zeros of the torque transfer function are computed and discussed for various system parameters. Identification of stator and rotor resistances is confirmed by simulation using a nonlinear system model. The proposed idea is applied to a speed sensorless system; this system has a similar configuration to those of existing systems under some assumptions. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(4): 66–76, 1997     

四轮毂电机电动车的电子差速控制方法

为了实现四轮独立驱动电动车电子差速系统,通过对电机驱动理论及传统电子差速方法进行分析,提出了基于4台无刷直流轮毂电机的控制方案,给出了控制器总体设计思路.采用全轮转向方式,利用Ackermann-Jeantand转向模型,计算了电子差速过程中随着转向角度变化的各个车轮的车速,同时分析了转向时转向轮之间的转矩分配问题.给出了电动车行驶时的四轮速度一致性协调方案,研究了车辆匀速运行和加减速运行时的工作状态,并确定了四轮驱动电动车转向时的电子差速控制策略.通过4台700W的8对极电机进行了仿真和空载实验,实验结果表明,电动车控制器设计合理,系统具有良好的动态性能;电子差速系统控制策略正确,能够满足四轮独立驱动电动车的行驶要求.     

基于参数局部最优化理论的电励磁直线同步电机自适应速度控制

建立适合速度控制器设计的电励磁直线同步电机连续时间数学模型,通过合理的假设建立初级电枢交轴电压与初级机械速度之间的单输入单输出传递函数。采用局部参数最优化梯度法设计了自适应速度控制器,仅含有一个积分器、一个乘法器以及2个比例单元。自适应速度控制器无传统控制器的电流内环加快了响应速度,简化了系统结构。利用MATLAB数值计算软件仿真所设计的控制器,分析自适应增益调节系数与广义误差反馈系数等因素对自适应速度控制系统稳定性与收敛性的影响,仿真结果验证了该自适应速度控制策略的有效性。     

Small-signal stability analysis of vector control system of induction motor without speed sensor using synchronous current regulator

This paper presents a stability analysis of a speed sensorless vector control (SSVC) system of an induction motor. The stability analysis takes into account the effects of three current control loops. The poles and zeros of the transfer functions for the rotor speed are calculated to investigate the influences of controller parameters and motor parameters. The theoretically derived step responses are compared with the experimental results. Also, the Bode diagrams of the transfer functions for the torque producing current are calculated. The settling time of the step responses of the rotor speed for the various designs of the current regulator (CR) is studied. This paper discusses the suitability of different CR methods for the SSVC system of an induction motor.     

基于VisSim异步电机矢量控制系统建模与仿真

为了建立一个高效、工程化的异步电机控制系统仿真模型,基于VisSim仿真平台,在分析交流异步电机数学模型的基础上,建立了电机独立功能模块,如电机本体模块、矢量控制模块、速度控制模块、电流滞环控制模块等,再将各模块有机整合,搭建了交流异步电机控制系统的仿真模型。系统采用双闲环控制,速度环采用PI控制,电流环采用电流滞环控制。仿真结果证明了该模型的合理性、有效性,为实际电机控制系统的设计和调试提供了新的思路。     

Load Sharing of Dual Motor Grinding Mill Drives

Relatively small slowly varying shaft position and velocity variations superimposed on the normal running speed of dual drive grinding mill motors can cause individual motor torque variations which disturb load sharing. The magnitude of load or torque unbalance is a function of the magnitude of the mechanical variation, the type of motors used, i.e., induction or synchronous, the number of motor poles, and the ratio of the gear connecting the motors to the load. When the magnitude is large enough to be of concern, it can be compensated for through motor secondary or field controls. How the causative factors relate, how dual drive motors should be specified for purchase are discussed, and a compensating load sharing controller for dual drive synchronous motors is described.     

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     

Optimum pole configuration of variable speed AC induction motors

Sometimes a user who is familiar with fixed speed AC induction motors may specify a variable speed AC requirement with a preconception of the number of motor poles. This is appropriate in the case of an application where the motor will be run “across-the-line”, and is expected to run at the same speed and load as provided on inverter operation. If, on the other hand, “bypass” operation is not required, a more optimal choice of motor designs might be available. For example, an application requiring 3000 or 3600 RPM operation would demand a two-pole motor design if bypass (at 50 or 60 Hz) must be provided. However, when bypass is not required, it is often the case that a smaller motor can be provided in a four-pole design (utilizing 100 or 120 Hz base frequency) compared to a two-pole configuration. Another aspect of applying adjustable frequency power supplies to AC induction motors is that it allows an essentially infinite number of possible “base speeds”, including base speeds in excess of 3600 RPM. In this paper the author discusses the number of poles required for fixed speed AC motors, DC motors, and adjustable frequency AC motors. Motor performance issues are also discussed     

基于自抗扰的感应电机无模型预测电流控制

针对采用传统比例积分(proportional integral, PI)控制算法的感应电机在面对复杂扰动时控制性能降低的问题,基于矢量控制系统,提出了感应电机的自抗扰(active disturbance rejection control, ADRC)无模型预测控制(model-free predictive control, MFPC)方法。首先,结合转速环和磁链环数学模型,设计了转速环和磁链环的ADRC控制器,对负载变化和内参摄动产生的内外扰动进行观测并补偿。其次,为避免内环控制器对电机参数的依赖,基于无模型控制原理,建立了dq电流环的超局部方程,将控制量之外的变量视为干扰量,并引入非线性扩张状态观测器估计干扰量。最后,结合预测控制思想设计了电流环控制器,得到开关状态作用于逆变器。仿真与实验结果表明提出的算法相对PI算法有更好的抗扰性和鲁棒性,可以有效提高感应电机的动态和稳态性能。     

单绕组多速电动机的设计和探讨

单绕组双速异步电动机是变极电机中方法最简易、应用最广泛的一种变极调速方法。变极电机的设计中,花费时间最多的是研究绕组的排列。通过槽电流表和槽磁动势图定性地分析电机的谐波磁场对电机运行性能的影响,由此确定电机所选槽配合是否合适。在工厂中,通过对现有的单速电机进行绕组改绕来设计单绕组多速电机。改绕计算主要是计算电动机磁路各部分磁通密度数值,不使其过大而致铁心严重饱和。在设计与计算过程中需要综合考虑2种极数下电机性能的特点。     

无刷直流电机双闭环控制系统的设计

在分析无刷直流电机的数学模型和传递函数的基础上,提出了一种无刷直流电机双闭环调速系统的控制策略,其外环采用转速PI控制,保证了调速系统的控制精度,内环则采用电流滞环控制方法,控制实际电枢电流快速跟踪参考电流,从而提高系统的动态响应性能。结合无刷直流电机的调速要求,详细分析了系统的开环传递函数,基于频域设计方法,给出了闭环控制系统参数设计的设计步骤,并由此设计出了控制器。最后,在Matlab仿真环境下,采用分段线性法实现了无刷直流电机的梯形波感应反电动势,建立了仿真模型,并结合前面的理论分析搭建了双闭环控制器。仿真结果表明,整个闭环系统运行平稳,具有良好的动、静态特性,从而验证了所提出的控制方法的正确性和有效性。     

A Speed and Power Factor Controller for Small Three-Phase Induction Motors

A form of controller/compensator is suggested for the speed control of small induction motors. This controller uses pairs of thyristors in each supply line, incorporated into a resistance/capacitance network. Smooth speed control may be realized over a wide speed range, and the motor current remains substantially sinusoidal. For a small laboratory type motor, the current was reduced by up to 30 percent, and high power factor was maintained over the whole speed range. The overall efficiency of the compensated system increased by about three percent over that of the uncompensated motor.     

A hybrid current controller for dual three‐phase permanent magnet synchronous motors

Control of the current harmonics is a critical issue for dual three‐phase (DTP) permanent magnet synchronous motors (PMSMs). Considering the limitations of conventional synchronous frame proportional‐integral (PI) current regulator, this paper presents a hybrid current controller that combines the PI current regulator with a multiresonant controller. With the proposed hybrid current controller, precise current control can be achieved with only a slight increase in the computational effort. Theoretical analysis and experimental results confirm the effectiveness of proposed current controller. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Wide range drive of hybrid stepping motor with flux‐weakening control

Because the application range of motors for position control is extending in industry, hybrid stepping motors that can realize position control easily have become popular. However, stepping motors have some disadvantages: the possibility of pull‐out under certain load conditions, and low efficiency due to iron loss. Consequently, a system designer must choose the motor‐driver combination very carefully. This paper proposes high‐efficiency drive of a hybrid stepping motor in a wide speed range by vector control, without the occurrence of pull‐out. It is shown that lead angle control is equivalent to flux‐weakening control, and that the maximum torque depends on the maximum inverter voltage at high speed. The effect of iron loss suppression by flux‐weakening control is verified experimentally. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 68–74, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21022     

Control System Design of a Current Inverter Induction Motor Drive

An analytical design is presented of the control system of a slip-controlled current inverter induction motor drive. First of all, the drive dynamics are modeled in a control-oriented perspective. Afterwards, the transfer function between the rectifier output voltage and the inverter current is thoroughly analyzed and the results used to design the current controller. Two function generators are then synthetized and incorporated in the speed loop so as to obtain constant rotor flux operation and satisfactory torque dynamics. Lastly, the speed controller is designed for a fast and accurate response. All the parameters of the control system are given in terms of performance specifications and drive data. A computer implementation of the drive system is carried out and performance tests are shown.     

Stability analysis of sensorless speed control of IPMSM

In the speed control of an interior permanent magnet synchronous motor (IPMSM), for stability reasons, the closed‐loop pole positions should be on the left‐hand side of the S‐plane, and for fast response requirements these poles should have a small time constant. Unfortunately, the motor poles have a very long time constant, which makes the system response very slow. To solve this problem, the zeros of PI controllers are used to compensate the motor poles. As the motor operates, the temperature increases, which changes the parameters of the motor and, accordingly, the motor poles change their position so the PI controller cannot compensate these poles. To solve this problem, many parameter estimation algorithms have been used to detect new parameter values and adapt the PI controller gains so that to compensate the motor poles continually. These parameter estimation algorithms complicate and add cost to the system. This paper demonstrates that, for a temperature up to 70 °C, the system is capable of giving fast response and stable operation by using a good design of the PI controller regardless of the parameter changes.