Electrical Parameter Estimation Method for Surface-Mounted Permanent Magnet Synchronous Motors Considering Voltage Source Inverter Nonlinearity

This paper proposes a method for online estimating the rotor flux linkage and voltage-source inverter (VSI) nonlinearity of permanent magnet synchronous machine (PMSM) drives. Thermocouples are employed for measuring the temperature variation of the stator winding in order to obtain the actual value of stator winding resistance. An Adaline estimator is used for online estimation of distorted voltage Vdead due to VSI nonlinearity. Both are subsequently used for the estimation of the rotor flux linkage. The proposed method is experimentally validated on a PMSM drive system and shows good performance in tracking the variation of the rotor flux linkage and compensating the VSI nonlinearity.

The nonlinearity of the voltage source inverter (VSI) leads to the error between output voltage and reference voltage, and causes the phase current harmonics. It is necessary to compensate its influence in the fields such as parameter identification, sensorless control, and servo drives. In this article, an industrial solution for VSI nonlinear compensation method based on lookup table (LUT) is introduced. The characteristics of semiconductor devices, equivalent dead-time and influence of parasitic capacitance effects are calculated quantitatively though injecting increase and decrease current during self-commissioning process. The critical current value for parasitic capacitor and the variation of equivalent dead time are verified through different distorted voltage curves. Considering dc-link voltage variation is irresistible for industrial products, 3-D linear interpolation is adopted to compensate the variation of VSI nonlinearity under different voltage conditions. Proposed LUT method does not require VSI datasheet and complicated calculation formula during implementation. Experiments are carried out on a commercial permanent magnet synchronous motor drive system to verify the proposed LUT method.

Direct torque control (DTC) is one of the most prominent control techniques used by permanent magnet synchronous motor (PMSM) drives in industry applications. Nevertheless, the presence of hysteresis controllers and inaccurate voltage switching table in traditional DTC results in higher torque and flux ripple. This study proposes an enhanced DTC functioned Surface‐mounted PMSM (S‐PMSM) drive with mitigation of torque and flux ripple. The operation relies on generating the reference voltage vector (VV) in a stationary reference frame, which supports control of torque and flux without hysteresis controllers. The reference VV generation is simple and does not affect control robustness. The position of reference VV in a sector is used to build the voltage vector (VV) switching table. As a result, the application of nearest discrete VV to reference VV produces optimal torque and flux control. Moreover, redundant switching combinations of null VV are effectively used for possible minimization of switching frequency of two‐level voltage source inverter (VSI) supplied S‐PMSM drive. Therefore, proposed DTC gains improved S‐PMSM drive response along with switching frequency reduction. In dSPACE‐RTI 1104 platform, experimental response of S‐PMSM drive under various operating conditions have been depicted to highlight the proficiency of proposed DTC in comparison with existing DTC.

For electric vehicles (EVs), permanent magnet synchronous motors (PMSMs) are competitive owing to their high power factor, high efficiency and high power density. In this paper, four types of PMSMs with different rotor topologies are designed with the same motor main dimensions and the same amount of permanent magnet usage. First, the different PMSMs are compared in terms of their torque characteristics. The torque characteristic curves of the four motors are displayed with the control method i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> =0 for surface-mounted PMSM (SPMSM) and Maximum Torque per Ampere (MTPA) for interior PMSM (IPMSM). It turns out that IPMSM has higher starting torque than SPMSM due to the reluctance torque. Among the three IPMSMs with different rotor structures, V-shape IPMSM and delta-shape IPMSM can provide higher output torque under the same current supply with the higher salient rate. More information on the no-load magnetic density, torque ripple, efficiency and demagnetization problem operated at the peak current is also provided and compared. Then the four PMSMs with the same peak current are further analyzed and compared on the flux-weakening speed-enlarge (FWSE) capability. The results show good FWSE capability for all of the four PMSMs owing to the large peak current. However, the torque of SPMSM in flux-weakening control region is slightly higher than the IPMSMs.

Sensorless technologies for the field-oriented control of the permanent magnet synchronous motors (PMSMs) are being actively developed today. Recently, a robust, nonlinear and globally convergent position observer for the surface-mount permanent magnet synchronous motor (SPMSM) has been proposed in [4]. The key feature of the robust observer is estimation of the rotor position requiring only the knowledge of the stator currents, voltages, resistance and inductance. However, the resistance and inductance of the stator may change during operation as a result of overheating, mechanical wear and environmental impacts. Thus, the aim of this study is to develop adaptive algorithms for the stator windings' parameters, which can be used for this position observer improvement. In this paper the authors propose four adaptive observers for estimation of the resistance and inductance at low motor speeds. It is assumed, that only currents and voltages of the stator windings are known. The other state variables and parameters of PMSM are unknown. The main idea of the synthesis of identification algorithms is linear filtering, which allows us to eliminate the unknown terms obtained by the mathematical transformations. Requirements to the external load, which ensure successful identification of the PMSM stator parameters, are given for each observer. The proposed adaptive observers for the stator resistance and inductance can be applied in case, when at low speeds, the field-oriented control of PMSM is carried out by means of Hall sensor, while at higher speeds, the sensorless control algorithms are used. A distinctive feature of the proposed estimation algorithms is that the resistance and inductance identification can be implemented during PMSM operation.

Permanent magnet synchronous motors (PMSM) generate high-frequency electromagnetic vibration and noise when powered by inverters, and the cause is high-frequency electromagnetic exciting force (EMEF). In this paper, the frequencies and orders of EMEF are analyzed. The expression of EMEF acted on the stator inner surface is derived and the frequencies and orders of main components of vibration are listed. The high-frequency vibration experiments are conducted on a surface mounted 8-pole and 12-slot PMSM. The high-frequency vibrations near switch frequency and its multiples are main components of vibrations of motors when powered by inverters, and experiments are conducted to study the influence of switch frequency on the vibration acceleration. The impacts of periodic frequency PWM and random frequency PWM on the vibration acceleration and peak value of its frequency spectrum are studied by experiments. Introduction The vibration of motors is one of the most important performance indicators. The noise generated by vibration will pollute our working and living environment. A severe vibration can even destruct the machine structure. There are higher requirements for vibration in special applications. While the application of inverter improves the dynamic performance of the motor, it causes high frequency vibration and noise. Many researchers have done a lot of work about the vibration and noise of motors. The frequency of noise of inverter-fed induction machine is calculated[1,2]. The influence of inverters on the vibration of axial flux PM motors is studied by finite element method(FEM) and experiments. The impacts of random PWM and harmonic injection is studied[4-6]. The effect of pulse frequency modulation(PFM) in reducing noise of induction motor is studied[7]. When powered by inverters, the stator current has a lot of time harmonics which increases the complexity of air gap flux. The air gap flux determines the magnitude and frequency of electromagnetic exciting force (EMEF) acted on the inner surface of stator. In this paper, the flux distribution is derived by magnetic circuit method firstly. Then, the expression of radial of EMEF is obtained by Maxwell’s stress tensor. The frequency, order and sources of the main EMEF are listed. The high-frequency vibration experiments are conducted on a surface mounted 8-pole and 12-slot PMSM. The high-frequency vibrations near switch frequency and its multiples are main components of vibrations of motors when powered by inverters, and experiments are conducted to study the influence of switch frequency on the vibration acceleration. The impacts of periodic frequency PWM and random frequency PWM on the vibration acceleration and peak value of its frequency spectrum are compared by experiments. Calculation of EMEF in PMSM The vibration of stator of PMSM is mainly determined by radial EMEF acted on the inner surface of the stator. Neglecting the effect of magnetostriction and assuming 0 Fe μ μ  , the EMEF acted on the inner surface can be expressed as[8]: 2nd International Conference on Electrical, Computer Engineering and Electronics (ICECEE 2015) © 2015. The authors Published by Atlantis Press 1580 2 0 1 2 n n o F B μ = (1) where 0n B is the radial air gap flux density in the inner surface of stator. So the air gap flux distribution need to be obtained before calculating the EMEF. Neglecting the core magnetic reluctance, the air gap flux distribution can be expressed as ( ) ( ) ( ) , , , b t f t t θ θ λ θ = ⋅ (2) where θ is the mechanical angle, ( ) , f t θ is the air gap magneto-motive force(MMF) and ( ) , t λ θ is the air gap permeance. In a surface mounted PMSM (SPMSM), the air gap permeance does not change with time. It can be approximately expressed as ( ) 0 l θ λ λ = Λ +∑ (3) where 0 Λ is the constant part and l λ is the space periodic part caused by slots. l λ can be expressed as ( ) ( ) ( ) 0 ( 1) sin 1 cos cos ( 1) l l k l k k lZ lZ k l k k δ

Permanent magnet synchronous motors (PMSMs) have been extensively adopted in a range of industrial applications, particularly in the electric vehicle industry, due to their high power and torque density, high efficiency, reliability, and excellent dynamic performance. Between the types of PMSMs, a surface-mounted PMSM (SPMSM) is characterized by identical &lt;i&gt;d&lt;/i&gt;- and &lt;i&gt;q&lt;/i&gt;-inductances, due to which it only generates magnetic torque. However, SPMSMs also exhibit higher flux density, since the air gap in these motors is smaller and the permanent magnets are located very close to the stator teeth. In contrast, an interior PMSM (IPMSMs) features different &lt;i&gt;d&lt;/i&gt;-axis and &lt;i&gt;q&lt;/i&gt;-axis inductance components, due to which it can create not only magnetic torque but also reluctance torque. In this paper, two processes are conducted to examine these motors. First, an analytical technique is proposed to design the required parameters for an SPMSM and an IPMSM, where the dimensions of the latter are defined using the fractional-slot concentrated winding configuration, and those of the former are designed based on the approach of keeping the rotor volume, permanent magnet volume, pole–slot combination, and power supply unchanged. Subsequently, a finite element method is presented for computing, simulating, and comparing the electromagnetic parameters of both proposed motors, including their back electromotive force, torque ripple, efficiency, and power factor. Finally, the proposed methods are validated using a 7.5 kW practical motor.

Stator winding inter-turn short circuit (ITSC) accounts for 21 % of faults in Permanent Magnet Synchronous Motors (PMSM). One of the biggest challenges in the area of inter-turn fault is to detect the fault having less than 10% of total turns in a phase. In this paper, an attempt is made to analyse stator inter-turn fault in Surface Mounted Permanent Magnet Synchronous Motor (SPMSM) using Finite Element Method (FEM). A 0.55 kW SPMSM model is obtained from ANSYS Maxwell finite element tool and it is linked to ANSYS Simplorer by transient - transient link to supply power and apply load to the motor. Three phase voltage source inverter with Space Vector Pulse Width Modulation (SVPWM) control technique is created in MATLAB Simulink and coupled with Simplorer to control the machine. Analysis is carried out for different inter-turn fault severities such as 15T (7.2%), 30T (14.4%) and 45T (21.6%) respectively. Various machine parameters such as phase current, torque, speed, flux distribution over the machine and radial air gap flux density are analysed and compared with faulty machines. It has been observed that flux density distribution is less in the stator teeth and core region of faulty coil and the rms value of winding current and radial air gap flux density increases proportionally with severity of ITSC fault. Empirical Wavelet Transform (EWT) is applied to analyse the stator current of SPMSM for various inter-turn severities. It is observed that peak magnitude of the EWT decomposed components increases when there is increase in severity of fault.

In this paper, an accurate parameter estimation model of surface permanent magnet synchronous machines (SPMSMs) is established by taking into account voltage-source-inverter (VSI) nonlinearity. A fast dynamic particle swarm optimization (DPSO) algorithm combined with a receptor editing (RE) strategy is proposed to explore the optimal values of parameter estimations. This combination provides an accelerated implementation on graphics processing unit (GPU), and the proposed method is, therefore, referred to as G-DPSO-RE. In G-DPSO-RE, a dynamic labor division strategy is incorporated into the swarms according to the designed evolutionary factor during the evolution process. Two novel modifications of the movement equation are designed to update the velocity of particles. Moreover, a chaotic-logistic-based immune RE operator is developed to facilitate the global best individual ( gBest particle) to explore a potentially better region. Furthermore, a GPU parallel acceleration technique is utilized to speed up parameter estimation procedure. It has been demonstrated that the proposed method is effective for simultaneous estimation of the PMSM parameters and the disturbance voltage ( $V_{\mathrm { {dead}}})$ due to VSI nonlinearity from experimental data for currents and rotor speed measured with inexpensive equipment. The influence of the VSI nonlinearity on the accuracy of parameter estimation is analyzed.

&lt;span lang="EN-IN"&gt;This paper presents a design of 15-slot/12-pole, five-phase, surface-mounted permanent magnet synchronous motor (PMSM). The five-phase PMSM can be an attractive solution to few applications that demand fault tolerant capability such as in aerospace engineering and electric propulsion. The motor model is first investigated based on the implementation of analytical method. The analytical method derived from the subdomain model of the permanent magnet machine is initially applied to estimate the magnetic flux density distributions for the radial component &lt;em&gt;B&lt;/em&gt;&lt;sub&gt;r&lt;/sub&gt; and the tangential component &lt;em&gt;B&lt;/em&gt;&lt;sub&gt;t&lt;/sub&gt; in the machine air gap. Other important motor characteristics such as phase back-EMF, line back-EMF, cogging torque and electromagnetic torque are also calculated. The analytically calculated results are then compared with the numerical method in a 2D finite element analysis. Additionally, the capability of this PMSM model against faulty conditions are further investigated. The results show that the analytical model of the 15-slot/12-pole, five-phase PMSM provides very accurate motor performance within acceptable error margin. For instance, the average electromagnetic torques, inclusive of the cogging torque, as computed by the analytical and numerical methods are 5.53Nm and 5.33Nm respectively, yielding an error of 3.6%. During faulty conditions, the PMSM can possibly continue to operate with lower output torque, about 60% to 80% of its rated torque, when one-phase or two phase windings are out of service.&lt;/span&gt;

A new instantaneous torque-control strategy is presented for high-performance control of a permanent magnet (PM) synchronous motor. In order to deal with the torque pulsating problem of a PM synchronous motor in a low-speed region, new torque estimation and control techniques are proposed. The linkage flux of a PM synchronous motor is estimated using a model reference adaptive system technique, and the developed torque is instantaneously controlled by the proposed torque controller combining a variable structure control (VSC) with a space-vector pulse-width modulation (PWM). The proposed control provides the advantage of reducing the torque pulsation caused by the nonsinusoidal flux distribution. This control strategy is applied to the high-torque PM synchronous motor drive system for direct-drive applications and implemented by using a software of the digital signal processor (DSP) TMS320C30. The simulations and experiments are carried out for this system, and the results demonstrate the effectiveness of the proposed control.

Permanent magnet synchronous motors have the advantages of high power density and high efficiency. The development of permanent magnet synchronous motor position servo control strategy research has an important technical support for improving my country’s basic industry. Taking the surface-mounted permanent magnet synchronous motor as the object, the id=0 control strategy is selected, and the three closed-loop control structure of position, speed and current is adopted to control the system. Among them, the speed loop and current loop adopt proportional integral controller. For the position controller, a comparative analysis of two different controllers, proportional control and feedforward control, is creatively adopted. The two control systems of the position controller are simulated and verified in the MATLAB/Simulink environment. Given a control signal, the simulation shows that the system using the feedforward controller is optimized in terms of steady-state position tracking accuracy, position overshoot, and tracking speed compared to the proportional controller.

This paper presents a new improved dynamic control (IDC) for the speed and currents of a surface-mounted permanent magnet synchronous motor (SMPMSM). In industry applications, standard proportional-integral (PI) controller is commonly used. Nonetheless, the load regulation capability and the tracking performance should be compromised in the designing process of the controller. The proposed IDC controller parameters are calculated based on the mechanical dynamic model and the predefined drive system performance. When the IDC parameters are obtained, the distinct speed performance can be accomplished at different operating conditions. A 850-W SMPMSM drive test setup, connected load, and the feedback sensors of the current and speed are emulated using the Typhoon Hardware-in-the-loop (HIL 402) tool with the dSPACE MicroLabBox. The performance of the proposed IDC scheme is evaluated through the verification results under rated speed reversal and load torque disturbance conditions. A comparative study between the proposed IDC and conventional PI controller is carried to confirm its simplicity, good performance, and robustness.

This paper concerns the speed regulation problem for permanent magnet synchronous motor (PMSM) drive system with matched and mismatched disturbance. A novel single-loop speed and current control strategy with continuous integral-type terminal sliding mode control (ITSMC) and disturbance observer (DOB) is proposed. Firstly, the nonlinear motor model including the lumped disturbance is constructed. Then, by introducing a virtual control, a continuous integral-type sliding mode controller, which has the non-cascade structure, is developed based on terminal sliding mode surface, and it has the globally asymptotic stability based on Lyapunov criterion. However, when the drive system has large disturbance, especially for unmatched external disturbance, the performance of the whole system will be influenced. To further improve the anti-disturbance performance, a disturbance observer is introduced to estimate both the matched and mismatched disturbance in the system, and it is used for the feed-forward compensation, and the stability of the system is proved. Finally, the novel scheme is tested on a surface-mounted PMSM by experiment, and the comparative results in different operation conditions verify that the proposed method has the fast transient response and the strong robustness for the disturbance.

This paper presents an improved position-sensorless field-oriented control strategy for a surface-mount permanent magnet synchronous motor (PMSM). In this algorithm, a high-pass filter (HPF) has been applied to the rotor flux estimation to solve the DC drift or offset problem caused by the integration part. The rotor position and speed signal extraction is achieved by mean of a phase-lock loop (PLL) as well as a phase compensation unit. This paper explains the design details of the adopted position-sensorless methodology. On the basis of this method, PMSM field orientation control strategy has been implemented to verify its correctness and reliability. Simulation has been carried out with MATLAB/Simulink. And a motor-generator experimental prototype setup has been built in the laboratory to testify its performance. Simulation and experimental results consistently prove the feasibility and precision of this estimation method.