Streamlined Methodology for E-Motor Performance Evaluation Using a Configurable Universal Inverter

매입형 영구자석 동기 전동기는 높은 효율과 빠른 동특성, 넓은 정출력 운전 영역 등의 장점 때문에 다양한 산업 분야에서 각광을 받고 있다. 특히 매입형 영구자석 동기기의 단위 전류당 최대 토크(Maximum Torque Per Ampere, MTPA) 운전 방법은 전동기의 최대 효율 운전을 위해서 필수적인 운전방법이 되었다. 이론적인 MTPA 운전점은 전동기의 제 정수에 의해 결정되는데, 매입형 영구자석 동기 전동기는 온도와 운전 영역에 따라 전동기 제 정수의 변화가 심하여 정확한 MTPA 운전을 하기 위해서는 전동기의 전 운전 영역에 대한 전동기 제 정수를 미리 알고 있어야 한다. 본 논문에서는 신호 주입 개념을 도입한 새로운 MTPA 운전 방법을 제안한다. 전류에 높은 주파수의 신호를 주입하여 그 주입된 신호에 의한 반응을 확인함으로 MTPA 운전점을 판별하게 된다. 이 방법은 전동기 제 정수 변동에 강인하며, 간단한 신호처리 과정을 통하여 MTPA 운전을 할 수 있다. Interior Permanent Magnet Synchronous Motor(IPMSM) have gained an increasing popularity in recent years for a variety of industrial applications, because of their high power density, high efficiency and possibility of flux weakening operation. Because the efficiency of IPMSM is one of the important performance characteristic, the Maximum Torque Per Ampere(MTPA) operating method has been indispensible. In theory, MTPA operating point can be calculated using the exact values of the machine parameters. However, the values of the IPMSM parameters are known to vary widely according to the operating condition. Therefore, to operate the IPMSM in the MTPA operating point, the machine parameters should be estimated in real-time. In this paper, the new MTPA operating method based on the signal injection is presented. By injecting the high frequency current signal, the MTPA operating criteria can be calculated by measuring the input power to IPMSM. The proposed method can find the MTPA operating point with simple signal processing regardless of the parameter variation.

When a permanent-magnet synchronous motor is driven by an electric tractor, potholes, sudden changes in speed and motor temperature rise may occur during transportation and plow operations. These factors may cause the motor operation and control parameters to change. The traditional maximum torque per ampere (MTPA) trajectory is based on the control parameters of the motor and the trajectory cannot be changed as the motor parameters change. However, the actual operation of the drive motor MTPA trajectory will change, which led to control deviation. This paper presents a torque current ratio limit tracking method, the torque in real time to consume the minimum current vector, MTPA trajectory closer to the actual operation of the motor drive MTPA curve, to obtain better maximum torque current ratio trajectory, the motor has More anti-interference. Through Simulink simulation and experimental verification, the improved MTPA algorithm can make the motor run more stable and can adapt to the harsh working environment of the driving motor.

The energy-shaping and maximum torque per ampere (MTPA) principle are used to develop the modeling and position tracking control of permanent magnet synchronous motor (PMSM) in this paper. Firstly, based on the port-controlled Hamiltonian (PCH) systems theory, a PCH position tracking control model of PMSM is established. Secondly, using closed-loop state error PCH control and MTPA method, the control strategy of PMSM is presented when load torque is known and unknown. The control problem of the PMSM is reduced to the solution of a partial differential equation. The partial differential equation can be transformed into a set of general differential equation by assigning desired interconnection and damping matrix. Finally, the equilibrium stability is also analyzed. The simulation results show that the proposed scheme exhibits good position tracking control and load torque disturbances attenuation performances.

In this paper, a maximum torque per ampere (MTPA) control strategy is presented for interior permanent magnet synchronous machines (IPMSMs) without current sensing or regulation. The developed control scheme achieves MTPA using a direct voltage control method, which varies the machine's stator voltage amplitude and angle. As such, no explicit current loop regulation is needed, which simplifies the control structure and unlike other control strategies, no parameter knowledge, voltage, or current transducer is required. Experimental comparison against the well-known MTPA vector control highlights the performance of the proposed controller in various conditions. Moreover, quantitative efficiency metrics are provided to better illustrate the MTPA trajectory tracking performance. Furthermore, the simplicity of the control scheme makes it a good candidate for low-cost implementation of real-time IPMSM drives.

In this paper, a modified control strategy of Finite-Control-Set Model Predictive Control (FCS-MPC) for the Interior Permanent Magnet Synchronous Motor (IPMSM) is proposed to solve the problem that the actual stator current cannot quickly track the given Maximum Torque Per Ampere (MTPA) current due to the integration saturation of the current regulator caused by sudden changes in load torque. The FCS-MPC controller is used to replace the PI current regulator, to obtain a more accurate voltage vector and achieve real-time dynamic tracking of the IPMSM MTPA target trajectory. The cost function of FCS-MPC control strategy is designed multi-objective combination to meet such requirements: torque tracking, MTPA current tracking and limitation of the maximum current. The simulation and experimental results show that the proposed control strategy can track the MTPA given current and torque in real time during load torque sudden changes.

A new mathematical model of the motor is established and then applied to a permanent magnet/reluctance hybrid rotor double stator motor (PM/RHR-DSM) with a series structure of inner and outer stator windings. And according to the motor voltage and current equations in new mathematical models, a new Maximum torque per ampere (MTPA) based on vector control system is designed to derive the current distribution equation of the motor by using the Lagrangian extreme value method. Since there is an angle of δ between the dq axis of the permanent magnet rotor part and the reluctance rotor part in PM/RHR-DSM. Therefore, compared with the traditional MTPA, the new MTPA needs to consider the influence of δ on the mathematical model of the motor and the effect of the inner and outer stator current vectors on the electromagnetic torque. The new MTPA minimizes the stator current amplitude when the motor outputs a certain electromagnetic torque, thereby reducing the inverter capacity. Simulation results show that the validity and practicability of the proposed mathematical model and MTPA control strategy.KeywordsPM/RHR-DSMMTPAVector controlStator windings in series

This paper proposes an overall maximum torque per ampere (MTPA) control for dc-biased hybrid excitation machine (dc-biased HEM) using MTPA control law and virtual signal injection. The mathematical model of the machine is first analyzed in synchronous rotating reference frame. According to the characteristic of the mathematical model, a control strategy is proposed and consists of two parts, i.e., an MTPA control law and a virtual dc-biased signal injection. The MTPA control law is employed to calculate the dominant current references while ensuring the rapid dynamic performance. The virtual dc-biased signal injection method is a correction scheme for MTPA current deviation caused by parameter variations. Unlike conventional signal injection techniques, this signal injection method considers the nonlinearity of inductance and does not involve any filters. Thus, it can extract MTPA criterion more accurately and easily. In general, simulation and experimental results validate that the control strategy combined with MTPA control law and virtual signal injection can achieve accurate MTPA operation and rapid dynamic magnetization capability for the dc-biased HEM in real time.

This study proposes a sensorless flux adaption direct torque and flux control (DTFC) for an interior permanent magnet synchronous motor (IPMSM), in which an maximum torque per ampere (MTPA) based on active flux and an adaptive second‐order sliding mode observer (SOSMO) are adopted. Flux adaption DTFC is proposed based on the existing active flux concept. Thus, the stator current amplitude can be minimised in both steady state and transient state. Furthermore, to realise the sensorless control of the IPMSM, an adaptive SOSMO is proposed. Compared with constant gains SOSMO, the gains of the adaptive SOSMO can be adjusted adaptively with the motor speed changing. Then, the precision of position estimation is enhanced effectively in a wide speed range. Numerical simulations and experiments with a 60 kW IPMSM are implemented. In addition, the results validate the capability of the proposed sensorless flux adaption DTFC scheme.

A performance comparison between a rareearth and a rare-earth-free five-phase PMa-SynRMs operating at maximum torque per ampere (MTPA) control is present in this paper under different open phase faults. The five-phase machines show inherent higher fault tolerance advantageous over the conventional three-phase machine under different number of open-phase conditions. Ferrite (Fe) magnets are cost effective replacement of the rare-earth material e.g. neodymium (Nd) magnets. Both magnets in PMa-SynRMs show degraded electromagnetic torque characteristics under different open phase faults. Traditional MTPA control method is not able to improve performance under faulty conditions. Advanced fault-tolerant MTPA control method is required to achieve satisfactory performance both under healthy and faulty conditions. In this paper, the fault tolerant control method is modified with MTPA technique to achieve higher performance. The proposed technique is applied on both machines under open phase faults to compare their performances. Detail theoretical analysis is carried out through MATLAB and finite element analysis (FEA). Experimental test results are provided for the Nd-based PMa-SynRM.

The paper studies the impact of first and third current-harmonic repartition in a five-phase Permanent Magnet machine whose Electromotive Forces (emfs) have first and third harmonics of the same amplitude. With a five-phase machine, it is possible for the torque production to achieve independent controls of the first and third harmonics of currents by using a vector control in each one of the two characteristic orthogonal sub-spaces of the machine. The same torque quality as obtained with a three-phase machine with sinusoidal emf can be thus obtained with a non-sinusoidal emf and with one more supplementary degree of freedom for the control. Based on the Maximum Torque Per Ampere (MTPA) strategy used for three-phase machines, a comparison of the obtained torque/speed characteristics of the machine is achieved using either one or two harmonics. The voltage limits imposed by the Voltage Source Inverter and two different values of the maximum allowed current densities are taken into account for obtaining the optimum repartition between first and third harmonics of currents: it appears that at first, from the point of view of efficiency, the MTPA is not optimal except for low speeds and secondly that the repartition of currents is not trivial and depends for example on the considered maximum current densities.

This article proposes an analytical formulation of a maximum torque per ampere (MTPA) technique, accounting for the magnetic saturation of the iron core, specifically developed for synchronous reluctance motors (SynRMs). The proposed MTPA is based on a magnetic saturation model of the SynRM, which has been obtained after simplifying a more complete magnetic model, including also cross-saturation effects. This simplified magnetic model, and consequently the proposed MTPA, can be easily parameterized directly starting from a unique set of tests for the off-line identification of the motor, without the need for any complex, time-consuming, and cumbersome finite-element analysis of the machine under test. The proposed MTPA has been tested experimentally on a suitably developed test set-up. Results obtained with the proposed MTPA have been compared experimentally with both the classic MTPA and the real MTPA. Results clearly show that the proposed technique permits a significant increase of the torque per ampere (TPA) with respect to the case of the classic MTPA, which does not consider magnetic saturation. TPA increase varies from 5% at 3 Nm load to 18% at 12 Nm load. Moreover, the loss of maximum torque, with respect to the real MTPA, obtained at the maximum speed and load torque with the proposed MTPA is about 15%, whereas the loss of maximum torque obtained with the classic MTPA is about 38.5%.

This article proposes a new online optimal tracking method with improved maximum torque per ampere (MTPA) and maximum torque per volt (MTPV) considering magnetic core saturation. The conventional optimality criteria for MTPA and MTPV do not consider magnetic core saturation, and therefore results in deviation from the optimal trajectory especially at higher load currents. This article establishes a mathematical formulation to consider magnetic core saturation in both MTPA and MTPV criteria and proposes corresponding new optimal conditions. The appropriate optimality conditions along with associated constraints form an optimization problem corresponding to an operating region. A simple and straightforward logic sequence proposed in this article identifies the operating regions and initiates corresponding online optimization to find the optimal reference currents at every sampling interval. Moreover, the proposed method ensures that the reference currents are always attainable by considering the inverter nonlinearity, winding resistance, and variation in dc-link voltage into the optimization problem. The proposed online optimal tracking method is successfully implemented in an off-the-shelf motor control unit, and the performances are experimentally validated for wide operating regions.

MTPA based operation point speed tracking for PMSM drives without explicit current regulation

In this paper, a one-step Model Predictive Control system is executed in the Multilevel modular converter (MMC) to control the speed of an Interior Permanent Magnet (IPM) machine. Maximum Torque per Ampere (MTPA) and Field Weakening (FW) control technique is utilized for the greatest yield torque. The proposed Control strategy tracks the reference produced by MTPA and FW calculation by freely directing voltages from the MMC modules. The proposed method also studies the relation between the switching losses of MOSFETs and sampling frequency, cost function and a number of modules in an MMC. Finally, simulation results are provided to demonstrate the appropriateness of this control procedure.

Sensorless Control of interior permanent-magnet synchronous motor with MTPA (maximum torque per ampere) control has been presented in this paper. PMSM has been controlled by estimating the rotor speed and angular position using Back-EMF Method. Interior PMSM is preferred due its extra reluctance torque production. Due to thermal or reliability constraints the maximum permissible current of the inverter or motor is limited. This also limits the torque capability. But MTPA control gives high efficiency as the stator current is lesser compare to conventional control. The MTPA control strategy mostly used in the efficient drive applications. This also attracts the researchers and technologist to work with Sensorless control in MTPA based PMSM drives. Simulation study has been done in Sensorless PMSM in terms of MTPA control with load changing.