Controlled Interior Permanent Magnet Research Articles

Maximum Torque per Ampere Control of Permanent Magnet Assisted Synchronous Reluctance Motor: An Experimental Study

In recent times, permanent magnet assisted synchronous reluctance motors (PMaSRM) have been considered as suitable traction motors for electric vehicle applications. In this type of machine, where the share of reluctance torque is more significant than the excitation torque, it is more appropriate to use a control strategy that can fully utilize the reluctance torque. This paper deals with a new structure of permanent magnet-assisted synchronous reluctance motors that was designed and manufactured in a previous study. This paper suggests applying, in a first study, a constant parameter maximum torque per ampere (MTPA) strategy to make a contribution towards the control of such structure that is becoming increasingly attractive in the field of electric transportation. This method is usually used to control interior permanent magnet synchronous motors to minimize the copper losses of the system. Before implementing and simulating this method, the mathematical models of the suggested motor and the inverter are given. An experimental study is conducted on a small-scale 1 kW prototype PMaSRM using a MicrolabBox Dspace to test and examine the proposed control. Simulation and experimental results are presented in this article in order to verify the validity of the developed control strategy.

Position sensorless starting method for IPMSMs by all‐pass filters

AbstractThis paper proposes the starting method for position sensorless controlled interior permanent magnet synchronous motors (IPMSMs) by using all‐pass filters. The starting of IPMSM position sensorless control is well known to be extremely difficult due to the lack of electromotive information. Therefore, IPMSM is often started and accelerated with the high‐frequency signal injection in general, and then, the control algorithm is switched to position sensorless control without high‐frequency injection in middle speed region. However, the acoustic noise due to high‐frequency signal injection would occur, and the switching of control methods would cause some bumps. For this reason, IPMSM is desirable to be driven from the start to the steady state without high‐frequency signal injection.This paper realizes to start the position sensorless controlled IPMSM without high‐frequency signal injection by allpass filter with the assistance of the appropriate initial vector setting of each controller, under the assumption that the high‐frequency signal injection is used only at standstill. Finally, this paper experimentally demonstrates the feasibility and the effectiveness of the proposed method.

Image Registration Technique to Improve a Self-Sensing Estimation for Model Predictive Controlled Interior PMSM Drives

Current responses based self-sensing control estimates rotor position by detecting magnetic saliency of a machine. However, the estimation error can be resulted from several nonideal factors, especially magnetic cross-saturation, as effects of these factors show up in current responses. This article applies image registration technique to improve the accuracy of a self-sensing estimation for model predictive control (MPC) interior permanent magnet synchronous machines (IPMSM) drives by minimizing impacts of nonideal factors on measured current responses. In commissioning process, two images are generated. The inverter voltage vectors in MPC excite current responses, represented by a set of vectors that generate a response image. Nonideal factors that result in estimation errors also deform the response image. A primitive image based on resolver output can be considered as a template. An image registration technique is investigated to register deformed images with corresponding primitive images, and transformations contain operations of rotation, scale, translation, and shear can be derived. During the drive, the deformed pixel points are online mapped to new pixel points by applying these operations. The current responses after transformation are less subject to nonideal factors. As a result, impacts of these deformation factors that contribute to estimation errors can be reduced. Finally, the application of image registration technique to the self-sensing estimation is verified on a 3.7-kW IPMSM drive.

SVM Direct Torque and Flux Control of Three-Level Simplified Neutral Point Clamped Inverter Fed Interior PM Synchronous Motor Drives

The direct torque and flux control abandons the current control approach but instead regulates the stator flux and torque directly and independently. Consequently, excellent dynamic performance can be expected from the motor drive, making it attractive for low and medium voltage applications. This paper presents a direct torque and flux controlled interior permanent magnet synchronous motor driven from a three level simplified neutral point clamped inverter. This inverter features fewer switching devices and less dc-link capacitor voltage imbalance problems due to the absence of the medium voltage vectors. A novel space vector modulation algorithm is proposed to generate the reference voltage vector for control purposes while balancing the neutral point voltage. The experimental results included verify the effectiveness of the proposed approach.

Analysis of Current Signals in a Partially Demagnetized Vector Controlled Interior Permanent Magnet Generator

Abstract This manuscript analyzes the operation of an interior permanent magnet (IPM) machine working as a permanent magnet synchronous generator (PMSG). The partial demagnetization operation is analyzed. To obtain more accurate voltages and currents of the machine, finite element analysis (FEA) is used in co-simulation with the full converter and the converter’s control algorithm. Direct field oriented control (DFOC) shows robustness by maintaining the speed even with a 25% demagnetized PMSG. Also, an analysis of the rotating reference frame DQ signals is done to asses demagnetization.

Voltage minimization control of vector controlled interior permanent magnet motor

Maximum Torque Per Voltage trajectory has been utilized only during field weakening operation of Interior Permanent Magnet (IPM) motor. In this paper, the voltage minimization control from zero-speed is proposed. Voltage minimization results in maximum torque per voltage control of IPM motor. The control implementation is also simple in comparison to current minimization, as the operation is always along the current-limit locus irrespective of operation in field-weakening. Voltage minimization technique minimizes the core losses whereas current minimization would minimize the copper losses. The mathematical model of IPM motor following voltage minimization is derived and the solution to the 4th order quartic equations is obtained using Ferrari’s method. The solution obtained is utilized to develop a look-up table for vector control of IPM motor. A comparative analysis of voltage minimization and current minimization is established which is supported by simulation results and demonstrated by detailed experimental results.

Direct Torque Control of Interior Permanent Magnet Synchronous Motors Based on Full-order Sliding-mode Flux Observer

This paper proposes a full-order sliding-mode stator observer. The observer takes the stator current and “active flux” as the state variables in the stationary reference frame, and can realize “active flux” estimation in the direct torque controlled interior permanent magnet synchronous motor driving system. Therefore, the stator and electromagnetic torque can be calculated with estimated active flux according to the relationship between active flux, stator and electromagnetic torque. As a result, the IPMSM high-performance speed closed-loop control is achieved. Simulation results are presented to validate the effectiveness of the proposed method.

Power Perturbation Based MTPA With an Online Tuning Speed Controller for an IPMSM Drive System

A novel maximum torque per ampere (MTPA) method based on power perturbation for a field-oriented control interior permanent magnet synchronous motor (IPMSM) drive system is proposed in this study. The proposed MTPA method, which is parameter independent and can improve the motor operation at both start-up and low speed, is designed based on the power perturbation by using the signal injection in the current angle. Moreover, the influence of current and voltage harmonics to the MTPA control can be eliminated effectively. Furthermore, to enhance the robustness of the control system, an online tuning scheme for an integral-proportional controller using a new wavelet fuzzy neural network with disturbance torque feedforward control is developed where the disturbance torque is obtained from an improved disturbance torque observer. Finally, some experimental results using an IPMSM drive system based on a low-price digital signal processor are presented. From the experimental results, the proposed control approach can guarantee the control performance of the speed loop, even under a cyclic fluctuating load.

Simplified current minimization control of vector controlled Interior Permanent Magnet motor

This paper presents a simplified current minimizing technique for Interior Permanent Magnet (IPM) motor. This is primarily achieved by utilizing normalized 2D-Look Up Table (LUT) that is parameter independent except for saliency ratio. In addition, torque-flux reference frame is considered for implementation to reduce the complexity generally present in conventional methods utilizing ids − iqs current reference frame. The proposed algorithm also incorporates both the aspects that lead to field weakening operation, i.e., increase in speed and reduction of dc link voltage. A novel compensation method for incorporating saturation effect is also addressed. The current minimizing technique is analyzed in detail, supported by experimental results.

Maximum power per VA control of vector controlled interior permanent magnet motor

Maximum Torque Per Ampere is the commonly used technique for operating interior permanent magnet (IPM) motor while little work is reported towards maximum power-factor operation i.e., Maximum Power Per Volt-Ampere (MPVA). The MPVA operation allows maximum-utilization of the drive-system. The control technique is developed using detailed mathematical model of IPM motor in MPVA, and the solution to the quartic equations involved is derived and analyzed. The solution is utilized to develop LUT for implementation of MPVA control. The comparison of MTPA and MPVA technique is established to demonstrate its merits and demerits. The proposed algorithm is supported by simulation and experimental results on a 5.5 KW vector controlled IPM drive.

Intelligent control for PMSM based on online PSO considering parameters change

A novel online particle swarm optimization method is proposed to design speed and current controllers of vector controlled interior permanent magnet synchronous motor drives considering stator resistance variation. In the proposed drive system, the space vector modulation technique is employed to generate the switching signals for a two-level voltage-source inverter. The nonlinearity of the inverter is also taken into account due to the dead-time, threshold and voltage drop of the switching devices in order to simulate the system in the practical condition. Speed and PI current controller gains are optimized with PSO online, and the fitness function is changed according to the system dynamic and steady states. The proposed optimization algorithm is compared with conventional PI control method in the condition of step speed change and stator resistance variation, showing that the proposed online optimization method has better robustness and dynamic characteristics compared with conventional PI controller design.

A power perturbation-based MTPA control with disturbance torque observer for IPMSM drive system

A novel maximum torque per ampere (MTPA) method based on power perturbation for a field-oriented control (FOC) interior permanent magnet synchronous motor (IPMSM) drive system is proposed in this study. The proposed MTPA method is designed based on the power perturbation resulting from the signal injection in the current angle. Moreover, the influence of current and voltage harmonics to the MTPA control can be effectively eliminated. Furthermore, to enhance the robustness of the control system, a real-time design scheme for the integral–proportional (IP) speed controller using a recursive least square (RLS) estimator with disturbance torque feedforward control is developed. The disturbance torque is obtained from an improved disturbance torque observer with online parameters updated. Finally, some experimental results using an IPMSM drive system based on a low-price digital signal processor (DSP) are presented. From the experimental results, the proposed control approach can guarantee the control performance of a speed loop even under a cyclic fluctuating load.

An Inverter Nonlinearity-Independent Flux Observer for Direct Torque-Controlled High-Performance Interior Permanent Magnet Brushless AC Drives

This paper introduces a novel flux observer for direct torque controlled interior permanent magnet brushless AC (IPM-BLAC) drives over a wide speed range including standstill. The observer takes machine nonlinearities into account and is independent of inverter nonlinearities, dead time, and armature resistance variation at steady states since such inaccuracies are compensated quickly by measured phase currents. Magnetic saturations in the stator and rotor cores, cross-coupling effects of flux linkages of the motor, and spatial harmonics in the magnetomotive force are all considered in the novel scheme. There is no filter; hence, no delays and oscillatory responses like in conventional schemes where filters are employed to prevent integrator drift issue. Superiority of the observer when compared to the state-of-the-art schemes has been illustrated by both extensive simulations and experimental results of a 10-kW IPM-BLAC machine designed for traction applications.

Design of Speed and Current Controllers Based on Online Particle Swarm Optimization Method for IPMSM Drives

In this paper, a novel online particle swarm optimization method is proposed to design speed and current controllers of vector controlled interior permanent magnet synchronous motor drives considering stator resistance variation. In the proposed drive system, the space vector modulation technique is employed to generate the switching signals for a two-level voltage-source inverter. The nonlinearity of the inverter is also taken into account due to the dead-time, threshold and voltage drop of the switching devices in order to simulate the system in the practical condition. Speed and PI current controller gains are optimized with PSO online, that means single irritation optimization computation can be completed within single sample time. In addition, the fitness function is changed according to the system dynamic and steady states. The proposed optimization algorithm is compared with conventional PI control method in the condition of step speed change and stator resistance variation, showing that the proposed online optimization method has better robustness and dynamic characteristics compared with conventional PI controller design.

IPM 모터의 출력밀도 향상에 관한 연구

Recently, it has to design the motor to raise power density because of many necessary application, such as home appliances and hybrid electric vehicles. Power of motor is made up of the torque and speed. So, if the motor which is the same size and shape is designed to raise speed, power and power density are increase.BR However, it is not easy to control interior permanent magnet (IPM) motor at high speed due to voltage constraint. So, this paper proposed simple method to solve the high speed control problem in the motor design stage, when it assumes that motor drive system has to have current margin. Basic idea is changing number of turns and current while retaining the same magnetomotive force (MMF) in this paper.

Maximum Power Point Tracking Control of IPMSG Incorporating Loss Minimization and Speed Sensorless Schemes for Wind Energy System

In the variable-speed generation system, the wind turbine (WT) can be operated at maximum power operating points by adjusting the shaft speed optimally. This paper presents a novel maximum power point tracking (MPPT)-based control of interior permanent-magnet (IPM) synchronous generator incorporating loss minimization algorithm (LMA). In the proposed method, without requiring the knowledge of wind speed, air density, or turbine parameters, MPPT algorithm generates optimum speed command for speed control loop of vector-controlled machine side converter. The MPPT algorithm uses the estimated active power output of the generator as its input and generates command speed so that maximum power is transferred to the dc link. The proposed control system also incorporates a LMA to minimize the losses in the generator and hence to improve the efficiency of the wind energy conversion system (WECS). A speed sensorless scheme is also incorporated to increase the reliability of the system. The performance of the proposed adaptive MPPT control of wind generator incorporating loss minimization and speed sensorless schemes is tested in both simulation and experiment at variable wind speed conditions.

Sensorless Direct Torque and Flux Controlled IPM Synchronous Machine Fed by Matrix Converter Over a Wide Speed Range

This paper proposes a new sensorless direct torque and flux controlled interior permanent magnet synchronous machine drive fed by a matrix converter. Closed-loop control of both torque and stator flux is achieved by using two PI controllers. The input and output voltage vectors are modulated with the indirect space vector modulation technique. Additionally, unity power factor on the power supply side of matrix converter is achieved through closed-loop compensation of the input displacement angle created by the input filter of matrix converter. The adaptive observer used for joint stator flux and rotor speed estimation is enhanced by HF signal injection scheme for stable operation at low speed including standstill. The stator resistance variation is compensated with the current estimation error. The operating range of the drive is extended into high speed region by incorporating field weakening. The sensorless drive exhibits high dynamic and steady-state performances over a wide speed range. The implementation of digital control system for the proposed matrix converter drive is described in this paper. Extensive experimental results confirming the effectiveness of the proposed method are also included.

Adaptive and robust speed control of interior permanent magnet synchronous motor drives

This paper presents a robust speed controller for field oriented controlled interior permanent magnet synchronous motor (IPMSM) drives. The proposed controller is designed using integral variable structure control (IVSC) combined with linear quadratic regulator (LQR). The LQR scheme is used to decide the optimal feedback gain to shape the system dynamics by tuning the IVSC switching plane to guarantee the robustness of the control algorithm. The complete drive is implemented in real-time using digital signal processor (DSP) control board DS1102. The tracking properties and robustness of the proposed scheme are examined through both simulations and experimental work. It guarantees accurate control performance in the presence of parameter variations, step speed change and load disturbances. The performance of IPMSM drive system with a conventional proportional-integral (PI) controller is presented in comparison with the proposed controller. The results show a significant improvement in both the transient and steady state responses over the conventional PI controller.

Ultrafast Finite-Element Analysis of Brushless PM Machines Based on Space

A computationally efficient method is proposed for the steady-state performance simulation of brushless permanent-magnet (PM) motors. Only a minimum number of magnetostatic finite-element (FE) analysis (FEA) solutions are used in conjunction with space-time transformations, which are based on the periodicity specific to synchronous machines. For an example electronically controlled interior PM (IPM) motor with six teeth per pole and a distributed winding, a single nonlinear magnetostatic FE solution was employed to estimate the flux density time waveforms in the stator teeth and yoke. Other results include core losses, back electromotive force, and torque. The extension of the method to fractional-slot topologies with reduced number of teeth and concentrated (non-overlapping) coils is discussed with reference to a nine-slot six-pole IPM motor example. The computational time is reduced by one to two orders of magnitude as compared with more laborious time-stepping FEA. Successful validation was performed against experimental data and detailed FEA results.

Field Oriented Control of IPM Drives for Flux Weakening Applications

Interior Permanent Magnet (IPM) drives are adapted to flux-weakening, then to constant power operation over a wide speed range. Most of the control strategies for IPM motor drives are based on the control of the current vector. Flux-weakening is obtained by proper current references, that are calculated according to the magnetic model of the motor. This approach needs the accurate characterization of the motor and it is sensitive to the inaccuracy and the variation of the model parameters. Moreover, in the case of a variable dc-link, an additional voltage loop is necessary to correct the current references values at different dc-link voltage levels. The direct control of the flux vector, in the stator flux oriented frame, is proposed here, with the aim of obtaining the constant voltage operation of the IPM motor drive in the flux weakening range by means of a very simple control algorithm. The proposed direct flux control is tested on an IPM motor drive designed for traction. The exploitation of the maximum torque in all the operating speed range is demonstrated. The control is also capable to adapt its flux and current set-points to different dc-link voltage levels with no need of additional voltage regulators. Discrete-time simulation and experimental results are presented and compared showing good accordance.