Novel permanent magnet motor drives for electric vehicles

Novel permanent magnet (PM) motor drives have been successfully developed to fulfil the special requirements for electric vehicles such as high power density, high efficiency, high starting torque, and high cruising speed. These PM motors are all brushless and consist of various types, namely rectangular-fed, sinusoidal-fed, surface-magnet, buried-magnet, and hybrid. The advent of novel motor configurations lies on the unique electromagnetic topology, including the concept of multipole magnetic circuit and full slot-pitch coil span arrangements, leading to a reduction in both magnetic yoke and copper, decoupling of each phase flux path, and hence an increase in both power density and efficiency. Moreover, with the use of fractional number of slots per pole per phase, the cogging torque can be eliminated. On the other hand, by employing the claw-type rotor structure and fixing an additional field winding as the inner stator, these PM hybrid motors can further provide excellent controllability and improve efficiency map. In the PM motors, by purposely making use of the transformer EMF to prevent the current regulator from saturation, a novel control approach is developed to allow for attaining high-speed constant-power operation which is particularly essential for electric vehicles during cruising. Their design philosophy, control strategy, theoretical analysis, computer simulation, experimental tests and application to electric vehicles are described     

Brushless permanent magnet (BPM) motor drive system usingload-commutated inverter

The goal of this work is to develop a brushless permanent magnet (BPM) motor drive system with low total system cost, high reliability and adequate performance for high-volume production and application to commercial appliances. The power converter used is a low-cost thyristor-based load-commutated inverter (LCI). Although LCIs have been used to supply sinusoidally excited permanent magnet motors, their application to BPM motors is a key contribution of this work. A detailed digital computer model capable of predicting the steady state as well as the transient performance of a BPM motor driven by an LCI has been developed. The utility-side phase-controlled rectifier, as well as the motor-side inverter-including the DC-link inductor, are modeled. A load-commutated inverter specifically designed to supply the BPM motor has been fabricated in the laboratory. The developed control strategy has been implemented on an INTEL 80C196KD microcontroller board. Simulation and experimental results to support the use of an LCI to drive a BPM motor are included in the paper     

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.     

Control characteristics and speed controller design for a highperformance permanent magnet synchronous motor drive

The theory of vector control is applied to the nonlinear model of a permanent magnet synchronous motor to develop a linear model for controller design purposes. The operation and relevant mathematics of a pseudo-derivative feedback controller are presented. Controller designs for three different speeds are then considered, and a comparative evaluation is made on the basis of their large and small-signal behavior. In order to test the large-signal response, the detailed nonlinear model of the machine and a real-time model of the inverter switches are used. Results indicate that a critically damped design done so as to ensure that all control and power signals never saturate gives an extremely poor result. Much better small and large-signal responses are achieved by avoiding this constraint and using Zener diodes instead to limit the commanded input into the inverter. Two designs using this technique are presented, an underdamped design with low speed overshoot and an overdamped design with no speed overshoot. The response of the underdamped design was much quicker than that of the overdamped. However the overdamped design has application when speed overshoot is intolerable     

永磁同步电机伺服系统的模糊控制

为了克服参数的不确定性,提高永磁同步电机伺服系统的快速跟踪能力,文中提出了一种自校正模糊控制器。该自校正模糊控制器与传统控制器相比,具有在线计算简单、减小稳态误差的优点。同时将其应用于永磁同步电机伺服系统的速度控制,证明了该模糊控制器的优越性。     

Disturbance rejection control method for permanent magnet synchronous motor speed-regulation system

The speed-regulation problem for permanent magnet synchronous motor (PMSM) system is studied in this paper. To guarantee the disturbance rejection ability of the closed loop system, most of the existing advanced control methods develop disturbance rejection control laws only for speed loop. To further improve the disturbance rejection ability, a control scheme which employs disturbance rejection control laws for not only speed loop but also the q-axis current loop, is developed here. Considering the dynamics of q-axis current, the coupling between rotor speed and d-axis current as well as the back electromotive force are regarded as lumped disturbances for the q-axis current loop, which are estimated by introducing an extended state observer (ESO). Thus a composite control law consisting of proportional feedback and disturbance feedforward compensation is developed to control the q-axis current. Simulation and experiment comparisons are presented to verify the effectiveness of the proposed method.     

Modeling of permanent magnet motor drives

Research has indicated that the permanent magnet motor drives, which include the permanent magnet synchronous motor (PMSM) and the brushless DC motor (BDCM) could become serious competitors to the induction motor for servo applications. The PMSM has a sinusoidal back EMF and requires sinusoidal stator currents to produce constant torque while the BDCM has a trapezoidal back EMF and requires rectangular stator currents to produce constant torque. The PMSM is very similar to the wound rotor synchronous machine except that the PMSM that is used for servo applications tends not to have any damper windings and excitation is provided by a permanent magnet instead of a field winding. Hence the d, q model of the PMSM can be derived from the well-known model of the synchronous machine with the equations of the damper windings and field current dynamics removed. Because of the nonsinusoidal variation of the mutual inductances between the stator and rotor in the BDCM, it is also shown that no particular advantage exists in transforming the abc equations of the BCDM to the d, q frame. Hence the solution of the original abc equations is proposed for the BDCM     

轮毂盘式无铁心永磁同步电机永磁体结构优化

从优化永磁体结构的角度出发,提出将不等厚排列技术与90°Halbach阵列相结合方法对磁钢的排列结构分析,通过改变磁钢排列结构以进一步提高盘式无铁心永磁同步电机(以下简称为DCPMSM)气隙磁密的基波幅值及波形的正弦性,达到提高电机性能的目的.本文通过有限元仿真软件对16极盘式永磁同步电机进行建模,分别选取不等厚排列电机模型、不等宽90°Halbach排列电机模型和改进型90°Halbach排列电机模型进行静态气隙磁场分析对比.仿真数据表明,"不等厚排列技术+90°Halbach阵列"使得周向磁密波形和切向磁密波形都大为改善,磁场波形更接近于正弦分布特征,其中周向磁密波形畸变率(THD)Bmin可降低到1.35%,气隙周向磁密幅值Bδav提高到0.5465T.     

Fractional order modeling and control for permanent magnet synchronous motor velocity servo system

This paper presents the application of fractional order system on modeling the permanent magnet synchronous motor (PMSM) velocity servo system. The traditional integer order model of the PMSM velocity system is extended to fractional order one in this work. In order to identify the parameters of the proposed fractional order model, an integer order approximation of the fractional order operator is applied and a state-space structure is presented for using the output-error identification algorithm. In real-time PMSM velocity servo plant, the fractional order model is identified according to some experimental tests using the presented algorithm. Two proportional integral (PI) controllers are designed for velocity servo using a simple scheme according to the identified fractional order model and the traditional integer order one, respectively. The experimental test performance using these two designed PI controllers is compared to demonstrate the advantage of the proposed fractional order model of the PMSM velocity system.     

永磁同步电机直接转矩控制系统的仿真研究

文章分析了永磁同步电机直接转矩控制的原理,阐述传统直接转矩控制系统转矩脉动的缺点,本文将空间矢量脉宽调制技术引入永磁同步电机的直接转矩控制系统中,利用空间矢量的调制过程,可在相同的系统硬件条件下得到更多的、连续的电压空间矢量,进而得到对电机更准确的控制。仿真结果表明,该方案既保持了直接转矩控制快速动态响应,又减小了电机转矩的脉动。     

永磁同步电动机控制策略综述

对永磁同步电动机控制策略进行综述.介绍发展中的永磁同步电动机控制系统的各种控制策略;给出不同解耦方法下控制系统的结构图.     

A permanent magnet hysteresis hybrid synchronous motor for electricvehicles

This paper presents the design, analysis and PWM vector control of a hybrid permanent magnet hysteresis synchronous (PMHS) motor with a view to improve the performances of motors for electric vehicle applications. This hybrid design combines the advantageous performance features of both conventional hysteresis motors and permanent magnet motors. Electrical equivalent circuits of the PMHS motor are developed for both the synchronous and asynchronous modes of operation. PWM vector control simulation results for the motor drives are given. Finally, a laboratory prototype hybrid hysteresis permanent magnet motor was built. Test results validate the superior performances of the new motor     

永磁同步电机优化控制

为了推进永磁同步电机在实际工程领域的应用,通过Matlab软件搭建了基于滑模变结构的永磁同步电机控制模型.为了使控制效果更加理想,提出了一种优化的指数滑模速度控制器,并针对这种连续的速度控制器在控制系统中进行了仿真.仿真结果表明,控制效果得到了很大改善.     

A sensorless initial rotor position estimation scheme for a direct torque controlled interior permanent magnet synchronous motor drive

In direct torque control (DTC) scheme, the requirement of the continuous rotor position sensor and coordinate transformation is eliminated since all the calculation is done in stator reference frame. However, the DTC scheme requires the position sensor to determine the initial position of the rotor at starting. Elimination of the shaft-mounted position encoder is a very desirable objective in many applications since this sensor is often one of the most expensive and fragile components in the entire drive system. This paper presents a sensorless method of determining the initial rotor position of a direct torque controlled interior permanent magnet (IPM) synchronous motor drive. The method consists of injecting a high frequency voltage to the windings and examining the effects of the saliency on the amplitude of the corresponding stator current components. This method does not depend on the level of static load and on any motor parameters. The magnet polarity of the rotor at its initial position is also identified using the effect of saliency. Modeling and experimental results verify the effectiveness of the proposed method.     

A novel two-degree-of-freedom controller design for a permanent magnet linear synchronous motor control system

This paper proposes a novel two-degree-of-freedom optimal controller design for a permanent magnet linear synchronous motor position-control system. The param-eters of the controller are obtained by using a frequency-domain optimization technique. A systematic design of the controller and the detailed implementation of the proposed system are discussed. The closed-loop control system possesses good transient responses and good load disturbance responses. In addition, the system has a good tracking ability. Several experimental results are provided to validate the theoretical analysis.     

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     

基于低分辨率霍尔传感器的电动汽车永磁同步电机驱动系统

考虑到对电动汽车永磁同步电机驱动的成本以及控制算法的复杂程度,在此研究一种基于低分辨率霍尔传感器的电动汽车永磁同步电机驱动系统。该系统采用三相对称开关型霍尔传感器进行位置估计。由于传统的基于平均速度的位置估算方法,在速度变化不大时,估算出的速度和位置值较准确,但是在电机加速、减速或者受到速度扰动时,估算出的速度和位置值就会存在较大偏差,严重影响系统的性能。因此这里使用基于平均加速度的位置估算方法,考虑当前扇区的加速度值,以减小估算误差。通过Matlab进行仿真研究,仿真结果表明,相比传统的基于平均速度的位置估算方法,基于平均加速度的位置估算方法无论是平稳运行阶段还是加速、减速阶段,系统估计速度和位置对实际速度和位置都具有较好的跟踪性能,速度超调量仅为2%。     

Microprocessor-based controller design and simulation for apermanent magnet synchronous motor drive

The speed control of a permanent magnet (PM) synchronous motor drive that is fed by a current hysteresis-controlled voltage-source inverter is investigated. The objective is to study the feasibility of implementing a microprocessor-based controller that may achieve complete software control of motor speed. A mathematical model and a digital control principle for controlling the PM synchronous motor are described. The sampling period and the controller parameters are determined analytically according to a linearized model. A systematic simulation procedure is proposed for verifying the feasibility of theoretical modeling and controller design. An experimental prototype system is constructed for correlating with the theoretical results. The experimental results closely follow theoretical predictions, thus validating the proposed control method     

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.