Design of Constraints for Seeking Maximum Torque per Ampere Techniques in an Interior Permanent Magnet Synchronous Motor Control

The efficient control of permanent magnet synchronous motors (PMSM) requires the development of a technique for loss optimization. The best approach is the implementation of power loss minimization algorithms, which are hard to model and design. Therefore, the developers typically involve maximum torque per ampere (MTPA) control, which optimizes Joule loss only. The conventional MTPA control requires knowledge of motor parameters and can only properly operate when these parameters are constant. However, motor parameters vary depending on operating conditions; thus, conventional techniques cannot be used. Furthermore, many industrial drives are designed for self-commissioning, and they do not have prior information on motor parameters. In order to solve this problem, various MTPA-seeking techniques, which track the minimum of motor current, have been developed. The dynamic performance between these seeking algorithms and maximum deviation from the true MTPA trajectory are defined by the constraints in most cases, in which proper design improves the dynamic behavior of MTPA-seeking algorithms. This paper considers a PMSM, which was designed to operate in the saturation area and whose MTPA trajectory significantly deviates from the same curve constructed for the initial unsaturated parameters. This paper considers existing approaches, explains their pros and cons, and demonstrates that these methods do not utilize full potential of the motor. A new constraint design was proposed and explained step by step. The experiment verifies the proposed technique and demonstrates improvements in efficiency and dynamic behavior of the seeking algorithm.

Performance Improvement of Reluctance Synchronous Motor Using Brain Emotional Learning Based Intelligent Controller

In this paper, intelligent control of a reluctance synchronous motor by an emotional controller, considering the effect of magnetic saturation on implementation, is analyzed; the maximum torque per ampere (MTPA) strategy is provided. According to the application of the proposed control scheme, the structure adequately performs the control of speed and magnetic flux of the reluctance synchronous motor drive. Additionally, the application of intelligent control based on an emotional learning system has provided adequate results to create a proper control process. The control function of a SynRM drive based on vector control in a rotor machine was compared with another based on emotional controllers and a PI controller regulated by genetic algorithms. The result of this comparison was the improvement of control functions by the controller based on the emotional controller. In addition, the MTPA based on search algorithms was well implemented in different situations. Due to its simplicity and independence from system parameters, the emotional controller can be considered as a potential operational method in the industry.

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.

Feedback Linearization and Maximum Torque per Ampere Control Methods of Cup Rotor Permanent-Magnet Doubly Fed Machine

This paper establishes the state-space model of the cup rotor permanent-magnet doubly fed machine in the synchronous reference frame. The feedback-linearization control method is used to realize the decoupling control of flux and torque. Then, the upper and lower load torque boundaries are solved. Furthermore, to minimize the stator current magnitude of the control machine under a certain torque, the maximum torque per ampere (MTPA) control is derived. Finally, simulation results demonstrate the good decoupling performance of the feedback-linearization control method and the correctness of the load torque boundaries. In addition, the effectiveness and robustness of the proposed control methods are also demonstrated.

Dependence of IPMSM Motor Efficiency on Parameter Estimates

The efficiency of an IPMSM motor is influenced by the operating point of the machine. Conventional approaches to generate measured efficiency maps may be too expensive to use in some situations, thus it often replaced by simpler variants based on parametric models. A promising approach is to combine model-based approaches with online parameter identification methods which would allow following changes of the parameters. However, such approaches may also result in deteriorated performance if the online parameter estimation is inaccurate. We present a systematic experimental study of the influence of the parameter estimates on the efficiency of a 4.5 kW IPMSM drive and analyze the sources of inaccuracy. The first outcome of this study is that none of the tested methods performs well when the machine is fully loaded, which deteriorates overall performance. The second outcome is that the conventional maximum torque per ampere/current (MTPA/MTPC) is not an accurate optimization criterion. The overall performance of the compared methods thus heavily depends on the testing profile. When a significant part of the profile is at full load, the methods based on online estimation are unsuitable and parameters estimated offline using frequency domain provides better efficiency under the maximum torque per current control strategy.

A novel MTPA and flux weakening method of stator flux oriented control of PMSM

Permanent magnet synchronous motor (PMSM) has the advantages of high efficiency, high power density and high reliability. It has been widely used in electric vehicles, rail transit, industrial transmission and other fields. Compared with the traditional PMSM control strategy, the Indirect stator-quantities control (ISC) of low torque ripple induction motor has high dynamic response performance in the whole speed range, with high stability and strong security. However, due to the inherent characteristics of PMSM, there are still some difficulties in applying ISC strategy, such as solving the load angle corresponding to the current torque, realizing the maximum torque per ampere (MTPA) control and flux weakening control method in the stator field oriented control algorithm of PMSM. In this paper, theoretical analysis and discussion are carried out for the above difficulties, and an indirect stator vector control (ISC) method for PMSM is proposed. Finally, combined with the electric drive application platform of electric vehicle, the simulation and experimental results verify that the proposed ISC control strategy of PMSM also has good dynamic and steady-state performance in the whole speed range.