An improved stator flux estimation for a variable structure direct torque controlled IPM synchronous motor drive using a sliding observer

This work focuses on performance improvements of the stator flux estimation for a direct torque controlled interior permanent magnet (IPM) synchronous motor drive. In this paper, an adaptive sliding observer is presented to estimate the stator flux linkage based on the motor current model. The observer has better dynamic behavior, disturbance resistance and high accuracy estimation ability. The experimental results show that the proposed observer is able to deliver more accurate estimation than open-loop estimator both in the steady state and during transients

This paper presents a sliding mode controller for an interior permanent magnet (IPM) synchronous motor, in which direct torque control (DTC) concept, variable structure control and space vector modulation (SVM) are integrated to achieve high performance. In comparison with conventional DTC, the inverter switching frequency is constant and controllable by using SVM, the torque and flux ripple are significantly reduced. The fast response and robustness merits of DTC are preserved. Position and angular speed of the rotor are obtained through an extended Kalman filter (EKF).

Synchronous homopolar motors (SHMs) with an excitation winding located at the stator and a toothed salient pole rotor are a good alternative to motors traditionally used in traction applications such as induction motors or interior permanent magnet synchronous motors (IPMSM). This study presents the results of a theoretical comparison between an IPMSM and an SHM in a traction application with a constant power speed range of 1:10, which is specific to the mining truck drives, and with a rated power of 370 kW. The considered IPMSM and SHM have the same number of phases, poles and stator slots, and the same outer diameter of the stator lamination. The IPMSM design is optimized using the Nelder–Mead method. The main objectives of optimization are to minimize the average losses in the operating cycle and to limit the required power of the semiconductor inverter. The performance of the optimized IPMSM is compared with the previously obtained performance of the SHM optimized by the same method. Although the average losses in the operating cycle in the compared motors are approximately equal, the losses at high speed for the IPMSM are about two times greater than at low speed with maximum torque, which means that there is a need to intensify the IPMSM cooling system and there is deterioration of reliability. The advantage of the IPMSM is the reduction in the length of the active part by 30%. The advantage of the SHM is that there is 4.6 times lower cost of active materials. In addition, the SHM is more reliable than the IPMSM, as there is no risk of overheating, demagnetization or degradation of permanent magnets over time.

Because traditional direct torque control (DTC) has unfixed switching frequency and ripple of torque and flux, deadbeat direct torque and flux control (DB-DTFC) of interior permanent magnet synchronous motor (IPMSM) is studied. At first, DB-DTFC based on IPMSM mathematical model is deduced. The calculated proper voltage vector can make reference torque and stator flux during one sampling period. But, parameters of IPMSM such as inductance of stator windings vary with its operation and affect on torque and flux performance. Secondly, parameter identification based on recursive least squares with forgetting factor is analyzed, which can identify IPMSM parameters online and eliminate their affects on performance of torque and stator flux. Finally, simulations are carried out and validate the proposed DB-DTFC which has both excellent dynamic and steady performance.

This paper proposes a novel control strategy of an interior permanent magnet (IPM) synchronous motor to obtain high input power factor of a diode rectifier. If the single-phase rectifier has much ripple voltage in the DC link, it can improve the input power factor and input current waveform. The energy of the power source provides directly to the IPM motor. The power converter doesn't need energy storage such as capacitors or reactors. Inverter control is based on energy flow of the power source. The q-axis control depends on the source energy ripple. By adjusting the flux to the DC voltage ripple, the inverter executes the field-weakening control. Making the best use of these special features, this paper shows that the proposed method can improve the input power factor over 97% by experimental results, and realizes small size and the long life of the inverter system.

This paper presents a novel model reference adaptive control (MRAC) of five-phase interior permanent magnet (IPM) motor drives. The primary controller is designed based on artificial neural network (ANN) to simulate the nonlinear characteristics of the system without knowledge of accurate motor model or parameters. The proposed motor drive decouples the torque and flux components of five-phase IPM motors by applying multiple reference frame transformation. Therefore, the motor can be easily driven below the rated speed with the maximum torque per ampere (MTPA) operation or above the rated speed with the flux weakening operation. The ANN based primary controller consists of a radial basis function (RBF) network which is trained on-line to adapt system uncertainties. The complete IPM motor drive is simulated in Matlab/Simulink environment and implemented experimentally utilizing dSPACE DS1104 DSP board on a five-phase prototype IPM motor.

– The paper presents a systematic comparison of four topologies of the interior permanent magnet machine (IPMM) designed for low speed applications. This comparative study investigates the suitability of the concentrated winding and distributed winding in the stator and the flat-shaped or V-shaped magnets in the rotor poles. The paper also studies the inductance characteristics of the designs using finite element analysis. Various steps taken to minimize the cogging torque and torque ripple in the studied machines were also discussed in details. Keywords : AC standstill saliency test, Cogging torque, Concentrated winding, Distributed winding, Direct-drive, Interior Permanent Magnet Machine, PM machine, Torque ripple 1. Introduction I n direct drive wind turbine systems, intermediate gear boxes are eliminated to increase the efficiency and reliability of the whole system, as well as reducing maintenances down-time. The generator used in such systems needs to have a low rated speed. This demand for an increase in the number of pole pairs of the generator. A review done in [1], [2] on direct-drive wind turbines suggests that permanent magnet (PM) machines are the most favorable for direct-drive wind turbine. While the most common type of PM machines used in the wind industry is the radial flux surface mounted magnet (SPM) type, an interior PM synchronous machine (IPMSM) offers a number of advantages over the SPM type. The most commonly cited advantages are: the presence of reluctance torque ( ) as shown in (1) in an IPM machine is beneficial in achieving a higher torque with lower magnet volumes and IPMSM has a mechanically and magnetically robust rotor. It should be noted that the presence of saliency in the IPSM results in the reluctance torque and also contributes toward the constant power speed range. A recent study carried out in [3] found that the use of an IPM machine in a small scale direct drive wind turbine can provide quicker return of investment compared to a SPM machine, especially in sites where average wind speed is low. According to [3] the return of investment can be achieved by taking advantage of provision for a constant power speed range available in IPMMs. But cogging torque in an IPMM is generally greater compared to a SPM machine due to the greater variation of reluctance between the stator and rotor [4]. This makes reduction of the cogging torque crucial in a low speed IPM machines [5]. The IPMSM with radially magnetized V-shaped (V-S) magnets has a better flux concentration and higher saliency ratio than its counter-part flat-shaped (F-S) magnet designs which makes it more attractive for traction drives [6]. The torque components of an IPM machine is (1) where, = magnet alignment torque, = cogging torque, and reluctance torque. The majority of IPM machines are designed with distributed windings (DW). Recently, the concentrated winding (CW) for the IPMSM is getting attention from the research community due to its high slot-fill factor, high tolerance to phase fault, simplified manufacturing process, non-overlapping coils resulting in shorter end-windings and reduced copper usage. In spite of having these advantages, the CW was not widely used in the past due to its characteristics in producing EMF and MMF waveforms with unacceptably high total harmonic distortion. However, in recent years, it has been shown that through appropriate choice of slot and pole combinations [7], the CW stator has the ability to produce sinusoidal EMF waveform with high a winding factor, and smooth average torque. In this paper, four design topologies of IPMSM were considered for investigation which includes (a) conventional distributed winding in the stator and flat-shaped IPM structure in the rotor( DW FS-IPMM), (b) distributed winding in the stator and V-shaped IPM structure in the rotor (DW VS-IPMM), (c) concentrated winding in the stator and flat-shaped IPM structure in the rotor (CW FS-IPMM), (d) concentrated winding in the stator and V-shaped IPM structure in the rotor(CW VS-IPMM). Fig. 1 shows the cross-section of the four topologies and no-load flux distribution. The objective of this paper is to present a detailed comparison of the major performance characteristics of all the four topologies illustrated in Fig.1. The selection process of the major dimensions and winding structure of the proposed IPMM is described in Section 2. Section 3 presents the cogging torque and torque ripple minimization of all the four investigated designs.

Efficient feedback linearization control for an IPMSM of EVs based on improved firefly algorithm

This paper describes a novel starting method used for interior permanent magnet synchronous motor (IPMSM) driven by a delta-modulated (DM) voltage source inverter (VSI) with the proportional integral controller. The IPMSM possesses several advantages, like high efficiency and high power factor, low weight/power ratio, low noise, and smooth operation; however, it also has significant starting problems, due primarily to magnet brake torque during the run-up period. The DM voltage source inverter can solve the on-line starting and smooth synchronization issues due to its inherently built-in V/f features [1]. A new PWM delta modulator scheme has been proposed in this work. The theoretical results are verified experimentally for a laboratory 1.5 kW interior permanent magnet motor.

A nonlinear Third-Order Extended State Observer (TESO) is proposed for the estimation of the rotor position and speed for sensorless Interior Permanent Magnet (IPM) synchronous motor drives. An optimized parameter tuning method is deployed to reconcile the needs of expanding the disturbance observation bandwidth and suppressing the measurement noise effectively. Both the steady state and transient performance of the TESO are verified through the experimental tests. In comparison with the performance of a conventional Linear Extended State Observer (LESO), the proposed observer is proved to have better noise suppression ability and disturbance observation performance in wide operating range.

The mechanism of torque ripple generation by time and space harmonic magnetic fields in permanent magnet synchronous motors is investigated to obtain advanced motor designs. The general expression between the torque ripples and harmonic air-gap flux densities in the motor is derived by using Maxwell stress tensor. Both the numerical and experimental verifications of this expression are carried out. By using this expression, the difference of the torque ripple generation between the surface and interior permanent magnet synchronous motors are discussed. Based on these investigations, the shape of the rotor surface of an interior permanent magnet motor is optimized. It is clarified that specific harmonic components of thetorque ripples in interior permanent magnet synchronous motors can be reduced to be nearly zero by optimizing the rotor surface shape.

This paper proposes a novel inverter drive system to improve the input power factor of single‐phase diode rectifier. Conventional rectifiers need a high‐frequency switching device and a reactor to improve the input power factor. However, the proposed power converter does not need the switching device, electrolytic capacitor, or reactor. By making many ripples across the DC‐bus voltage, the input power factor can be improved. The proposed system consists of only a single‐phase diode rectifier, small film capacitor, three‐phase inverter, and motor. The proposed system adopts an interior permanent magnet (IPM) synchronous motor. The IPM motor is well known as a high‐efficiency motor and can realize field weakening. The basic ideas of the inverter control method are based on the following operations: the inverter's controlled synchronous with the DC‐bus ripple voltage by field‐weakening method, and direct active power feeding from the source side to the motor without smoothing the DC‐bus voltage. This paper describes that the proposed method can obtain an input power factor of 97.3% by experimental tests, and realizes the goals of small size and long life of the system. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 66–73, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20047

The increase of pole numbers of the interior permanent magnet (IPM) synchronous machine can boost its air gap flux density, raise its efficiency and torque, and reduce its volume and weight. With the help of geometry module, this paper analyzes the relation between "flux concentration function" and the pole pair numbers of IPM synchronous machine, discusses connections between pole numbers and air gap flux density, per pole flux, non-load electric potential, flux density of rotor lead magnet material, flux density of stator tooth, flux density of stator yoke, and power which permanent magnet of unit volume produce respectively. Finally, authors point out: (1) when the saturation of lead magnet material was considered, the air gap flux density and the sums of the per pole flux will produce a the maximum with the increase of pole pairs, that is, IPM machine has a suitable pole pairs; (2) IPM machine bears "flux concentration function", when its pole pairs is more than or equal to 3, B/sub /spl delta///B/sub M/>1 or 4, B/sub /spl delta///B/sub r/>1; (3) the pole pairs of the IPM machine, which be from 3 to 6, is suitable. (4) the inner flux density of permanent magnet and power produced by the permanent magnet of unit volume will drop with the increase of pole pairs of the IPM machine.

The interior permanent magnet (IPM) motors are widely used in electric vehicles for high torque and power density and reliable structure. As a key component in the drive system, IPM has become one of the most critical elements in the electromagnetic interference (EMI) propagation path. Different from the induction motor, the impedance curves of the IPM motor vary with the rotor position, due to the permanent magnet and the saliency effect. The paper expounds the mechanism which makes the difference between the IPM and induction motor, and analyzes the impedance characteristic of IPM motor, finally suggests a high frequency model. The abstraction of the value of the parameters has also been involved.

Development of an interior permanent magnet motor through rotor cooling for electric vehicles