Optimal torque control of permanent magnet synchronous machines using magnetic equivalent circuits

In recent years, permanent magnet synchronous machines (PSMs) are often designed in a mechatronic way to obtain e.g. special torque characteristics at zero currents or maximum efficiency. These designs are often characterized by a pronounced magnetic saturation and non-sinusoidal properties. This paper describes the optimal torque control of such PSMs utilizing a magnetic equivalent circuit (MEC) model. In contrast to approaches based on fundamental wave models (dq0-models), which utilize the Blondel–Park transformation and typically consider saturation and non-sinusoidal characteristics only in a heuristic way, MEC models allow to systematically account for these effects. Given the MEC model, optimal values for the coil currents are obtained from a constrained, nonlinear optimization problem, which can be efficiently solved by exploiting the special mathematical structure of the model. The results of the optimization are used in a flatness-based torque control strategy. The performance and practical feasibility of the proposed torque control concept are demonstrated by experiments on a test stand. Finally, it is shown that using this torque control in an outer angular speed control loop also proves to be beneficial.     

Current control of permanent magnet synchronous machines.Experimental and simulation study

The control structure of a PWM (pulsewidth modulation) inverter-fed sinusoidal synchronous motor commonly includes two or three current control loops. Previous simulation studies have shown that the three-loop structure should be preferred: hence the neutral-point voltage can move freely. To obtain the same results with the two-loop structure, a more complex control variable limitation strategy is compulsory. However, the three-loop structure is very sensitive to imperfections in the control system (gain errors and offsets). Simulation and experimental results for both structures are compared and the influence of a neutral-point voltage (NPV) feedback loop to cancel homopolar errors in the three-loop structure is discussed     

Speed control of permanent magnet synchronous motor using boundary layer state observer

A speed control of a permanent magnet (PM) synchronous motor using the boundary layer state observer which is insensitive to the nonlinearities and the flux linkage variation of a permanent magnet is derived. This state observer reconstructs the electrical and mechanical states of the motor from the current and voltage measurements. The observer states converge at least to some arbitrary small neighbourhood of the true states.<>     

Modeling of a permanent magnet linear synchronous motor using magnetic equivalent circuits

This paper presents a modeling framework for permanent magnet linear synchronous motors based on magnetic equivalent circuits. In comparison to the commonly used dq0 model, the proposed modeling approach is able to systematically include magnetic saturation effects and has no restriction to harmonic motor quantities. In contrast to existing work, a differential magnetic equivalent circuit network is used to describe the stator quantities and the complete model is derived using a graph-theoretic approach. Furthermore, the resulting model is calibrated with measurements on a test bench and validated with additional measurement scenarios.     

A direct torque control algorithm for permanent magnet synchronous motors with minimum torque pulsation and reduced electromagnetic interference noise

In this work, a sensorless hysteresis direct torque control (HDTC) algorithm for a permanent magnet synchronous motor is described. The algorithm uses the output of two hysteresis controllers used in the traditional HDTC to determine two adjacent switching vectors per one sample time. The algorithm also uses the magnitude of the torque error, magnitude of the flux error and stator flux position to select the switching time for the selected vectors. The selection of the switching time utilises table structure which reduces the complexity of calculation. The simulation results of this proposed algorithm show adequate dynamic torque performance and considerable torque ripples reduction as well as lower current ripples and reduced electromagnetic interference noise level, as compared with HDTC.     

稀土永磁同步电动机失磁对电机损耗的影响

研究表明,与一般电机相比,稀土永磁同步电动机的平均节电率可达10％以上,专用稀土永磁电动机的节电率高达15％～20％。但是,由于该类型电动机采用稀土永磁材料励磁,永磁材料的特性决定了永磁同步电动机在运行时容易受到温度、电枢反应、机械振动等因素影响产生失磁故障,使电机损耗增加、性能下降甚至停转。在此基于有限元电磁场分析软件Ansoft13对调速永磁同步电动机进行建模仿真,模拟其发生失磁故障的状态,对失磁故障状态下电机的铜耗和铁耗进行定量分析,研究稀土永磁同步电动机失磁程度与电机损耗的动态关系。这些研究表明在电机设计和运行过程中采取措施降低其不可逆失磁是非常重要的。     

A SPICE model of a permanent magnet synchronous motor with a light load

A simple and accurate model of a permanent magnet synchronous motor (PMSM) with a light load is presented in this paper. The light-load condition is always needed in integrated circuit manufacturing machines in order to achieve a fast, accurate and minimum overshoot response. The model proposed here can help a designer to specify the controller's specifications and also to verify the hardware of motor drives. The differential equations of the PMSM are handled by the macromodels in PSPICE^TM. Moreover, it is revealed that the PMSM system is operating in a 4-state mode rather than a 2-state mode. Experimental results are provided to verify the simulation results of this model. The heavy load condition is also simulated.     

空调永磁同步电机轴电压原理及对策

随着永磁同步电机在空调系统应用越来越广泛,轴电压的问题不但影响电机本身的噪音及安全稳定性,而且对整个空调系统都会带来危害.本文采用建模的方法对常见空调系统里的永磁同步电机轴电压产生的原理进行理论分析,并结合实例分析轴电压的预防和防治.     

基于神经元自适应PID永磁同步电机的仿真与研究

针对传统PID控制器参数固定,处理非线性时变系统的局限性,提出神经元自适应PID控制算法。以传统PMSM转速控制为基础,采用神经元自适应PID控制方式,选用Hebb学习算法,以误差平方为性能指标实现参数在线调整,进而实现电机转速的快速跟踪。逆变器环节采用非正交坐标系下SVPWM算法,简化矢量算法步骤。仿真结果表明,对比传统PID控制方式,神经元自适应PID控制系统作用永磁同步电机,可以达到响应快、精度高的控制效果。     

Design of fast-response current controller using d-q axis crosscoupling: application to permanent magnet synchronous motor drive

A new current controller, which has both fast transient response in the transient state and high accuracy in the steady state, is proposed. In this scheme, a reference modification part is incorporated with the generally used synchronous frame proportional integral (PI) controller for the fast transient response. Through experimental results, it is observed that the proposed controller has much less transient time than the conventional synchronous PI regulator     

六相永磁同步电机串联系统控制的两种方法分析研究

笔者以逆变器驱动两台双Y移30°永磁同步电机(PMSM)的串联系统为例,给出了串联系统的工作原理,采用id=0的矢量控制策略及电流滞环控制和PWM载波控制两种控制串联解耦的方法。在Matlab/simulink环境下,分别用这两种方法对两台电机串联系统的运行特性进行仿真研究。当其中一台电机转速、负载变化时,分析两种方法...     

Design and experimental validation of doubly salient permanent magnet linear synchronous motor for precision position control

A typical iron-core permanent magnet linear synchronous motor (PMSLM) suffers force ripple originated from detent force. Rare earth permanent magnets (PMs) in stationary part cause cost issue. This paper introduces a doubly salient PMLSM (DSPMLSM) which reduces force ripple and number of PMs in stationary part. A prototype DSPMLSM is made based on geometry optimization by response surface methodology (RSM) considering multiple responses combined with 2D finite element analysis (FEA). Analysis and experimental results show promising results that the proposed DSPMLSM displays low force ripple and good positionability.     

Design and implementation of an extended Kalman filter for thestate estimation of a permanent magnet synchronous motor

Practical considerations for implementing the discrete extended Kalman filter in real time with a digital signal processor are discussed. The system considered is a permanent magnet synchronous motor (PMSM) without a position sensor, and the extended Kalman filter is designed for the online estimation of the speed and rotor position by only using measurements of the motor voltages and currents. The algorithms developed to allow efficient computation of the filter are presented. The computational techniques used to simplify the filter equations and their implementation in fixed-point arithmetic are discussed. Simulation and experimental results are presented to demonstrate the feasibility of this estimation process     

Implementation and experimental investigation of sensorless speed control with initial rotor position estimation for interior permanent magnet synchronous motor drive

In this paper, a new approach to sensorless speed control and initial rotor position estimation for interior permanent magnet synchronous motor (IPMSM) drive is presented. In rotating condition, speed and rotor position estimation of IPMSM drive are obtained through an extended Kalman filter (EKF) algorithm simply by measurement of the stator line voltages and currents. The main difficulty in developing an EKF for IPMSM is the complexity of the dynamic model expressed in the stationary coordinate system. This model is more complex than that of the surface PMSM, because of the asymmetry of the magnetic circuit. The starting procedure is a problem under sensorless drives, because no information is available before starting. The initial rotor position is estimated by a suitable sequence of voltage pulses intermittently applied to the stator windings at standstill and the measurement of the peak current values of the current leads to the rotor position. Magnetic saturation effect on the saliency is used to distinguish the north magnetic pole from the south. To illustrate our work, we present experimental results for an IPMSM obtained on a floating point digital signal processor (DSP) TMS320C31/40 MHz based control system.     

A novel direct torque controlled interior permanent magnet synchronous machine drive with low ripple in flux and torque and fixed switching frequency

A modified direct torque control (DTC) scheme for interior permanent magnet synchronous machine (IPMSM) is investigated in this paper, which features in very low flux and torque ripple and almost fixed switching frequency. It is based on the compensation of the error flux linkage vector by means of space vector modulation. Modeling and experimental results show that the flux and torque ripples are greatly reduced when compared with those of the basic DTC. With the new scheme, very short sampling time is not essential. All the advantages of the basic DTC are still retained. In addition, fixed switching frequency at different operating conditions becomes possible. The field-weakening control of this drive is also studied; an IPM DTC drive with a wider operation range and lower flux and torque ripple has been achieved experimentally.     

Instantaneous power control of a high speed permanent magnet synchronous generator based on a sliding mode observer and a phase locked loop

This paper proposes an instantaneous power control method for high speed permanent magnet synchronous generators (PMSG), to realize the decoupled control of active power and reactive power, through vector control based on a sliding mode observer (SMO), and a phase locked loop (PLL). Consequently, the high speed PMSG has a high internal power factor, to ensure efficient operation. Vector control and accurate estimation of the instantaneous power require an accurate estimate of the rotor position. The SMO is able to estimate the back electromotive force (EMF). The rotor position and speed can be obtained using a combination of the PLL technique and the phase compensation method. This method has the advantages of robust operation, and being resistant to noise when estimating the position of the rotor. Using instantaneous power theory, the relationship between the output active power, reactive power, and stator current of the PMSG is deduced, and the power constraint condition is analysed for operation at the unit internal power factor. Finally, the accuracy of the rotor position detection, the instantaneous power detection, and the control methods are verified using simulations and experiments.