A kind of MTPA control method for interior permanent magnet synchronous motor with parameter identification.

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.

The winding of the motor stator coil can be faulted due to high voltage, high temperature stress and etc. In the ITF (Inter Turn Fault) winding, large fault current, ohmic loss, and excessive winding heat are induced. As a result, fault aggravation and machine burning might happen unless adequate fault diagnosis and management are equipped. By limiting the copper loss by the ITF, the faulted motor could operate without aggravation till the adequate fault management action is performed. In this paper, an IPMSM (Interior Permanent Magnet Synchronous Motor) ITF tolerant drive method by limiting internal copper loss is proposed. The copper loss by the ITF is made simple for the proposed method and analyzed with various current, speed, and output torque condition. By maximizing the output torque with minimum IPMSM copper losses, MTPL (Maximum Torque Per Loss) operation point is suggested. Compared with the MTPA (Maximum Torque Per Ampere) the MTPL is more efficient operation point with ITF. To verify the proposed method, experiment studies are performed with an IPMSM with an ITF. The results show the feasibility and practicality of the proposed method.

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.

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.

Interior permanent magnet synchronous motors (IPMSMs) are used for various applications and high efficiency control is required. Maximum torque per ampere (MTPA) control is one of the methods to control IPMSMs with high efficiency. Because the motor parameters vary with magnetic saturation, MTPA control cannot be easily realized. Here, we propose a fully online and automatic MTPA control method. To find the MTPA point while driving the motor, it is necessary to predict the entire flux linkage surface. Therefore, the flux linkage surface is approximated by a plane from the sensor information at a specific current condition that considers the effect of magnetic cross saturation. The MTPA control is achieved using the estimated flux linkage plane and the gradient ascent method. The simulation results showed that the torque was maximized in two search periods, which was completed in 0.06 s. The proposed method was effective for a wide current range.

In this paper, a comprehensive and practical method of implementing speed range extended maximum torque per ampere (MTPA) control for permanent magnet synchronous machine (PMSM) is presented. The inverter-based method of measuring PMSM parameters, including winding resistance and d- and q- axis flux linkages, is introduced. The nonlinearities of the inverter, including voltage amplitude error and voltage phase shift, are identified and compensated, which improves the accuracy of the characterized flux linkage. The extended MTPA current references are obtained by employing nonlinear optimization algorithm, and the results are verified analytically on the current plane. MTPA control is applied on the PMSM experimentally in the entire speed range. Current transition, torque control accuracy, and efficiency performance are measured in the entire torque–speed range.

In this paper, a linear torque control strategy is first proposed for interior permanent magnet synchronous motor drives to fully utilize the reluctance torque and simplify the controller design. The proposed linear torque control strategy also extends the existing maximum torque per ampere control in the constant torque limit region up to the entire field-weakening region. It is found that in an intermediate speed region, called partial field-weakening region, the existing maximum torque per ampere control can still be applied under lighter load condition. In addition, the proposed control can also achieve the objective of minimum copper loss (i.e., maximum torque per ampere) for the entire speed range. Sound theoretical basis is given in the context. Moreover, an adaptive limiter is proposed for efficiently implementing the proposed control strategy over the entire speed range. Finally, a prototype is also constructed by using a fixed-point DSP TMS320F240 and some experimental results are given to verify the validity of the proposed control strategy.

In this paper, an experimental investigation on the comparison between the Maximum Torque Per Ampere (MTPA) and the Field Orientation Control (FOC) algorithms for interior permanent magnet synchronous machines (IPMSMs) is described, analyzed and discussed. This investigation was carried out on a small-power IPMSM with low saliency ratio. More in detail, after a previous simulation study, the control techniques have been experimentally implemented and validated through means of a dSPACE® rapid prototyping system. The performances of the two algorithms have been evaluated and compared, obtaining interesting results.

Signal-injection-based methods are a kind of competitive maximum torque per ampere (MTPA) control schemes for interior permanent magnet synchronous motor drives, due to their motor parameter independence and satisfactory control performance. However, the high current spectrum peaks (CSPs) produced by the conventional fixed-frequency injected signals may cause negative effects. To deal with this problem, an MTPA control method based on pseudorandomly reversed fixed-frequency (PRRFF) sinusoidal signal injection is proposed in this article. The PRRFF sinusoidal signals are injected into the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis currents via a specific current loop, and the MTPA operating points can be detected utilizing the resultant system response. Benefiting from the random characteristic of the injected signals, the proposed method can achieve far lower injection-induced CSPs than the conventional fixed-frequency injection methods. Moreover, benefiting from the fixed-frequency characteristic of the injected signals, the proposed method avoids the difficult matching of candidate injection frequencies that exists in the pseudorandom-frequency injection method. The validity of the proposed method is confirmed by experiments.

This manuscript proposes an efficient, straightforward, direct voltage maximum torque per ampere (MTPA) control scheme for an interior permanent magnet synchronous motor (IPMSM) propelling an electric vehicle (EV). The main feature of the traction control scheme is that the MTPA is attained by directly varying the amplitude and angle of the voltage vector, eliminating the need for current control loops and associated regulators. Instead, a single-speed controller is adopted. Furthermore, an analytical formulation based on the motor voltage model is developed to extract the desired voltage’s magnitude and angle to run the motor within the MTPA operating points, disregarding numerical solutions, control law approximation, long-winded iterative calculations, or approximate representation of the IPMSM. Such a methodology significantly reduces control scheme complexity, enhances computational efficiency, and mitigates the delays associated with cascaded-based control systems. Additionally, it facilitates straightforward real-time implementation. The performance of the designed algorithm is experimentally validated using commonly adopted driving cycles, namely the Federal Test Procedure (US06) drive cycle and the New European Driving Cycle (NEDC). The validity test is performed using a 5 HP IPMSM. Based on the driving cycles employed, an intensive comparative evaluation against MTPA field-oriented control (FOC) is established. A quantitative assessment is conducted using the MTPA FOC as a benchmark to investigate energy consumption. This assessment reveals that the designed strategy achieved energy savings of 1.318% and 2.26% under US06 and NEDC, respectively, compared to the MTPA FOC. The proposed method’s speed-tracking accuracy and computational efficiency are also investigated and compared to the FOC and existing direct voltage approaches, demonstrating an average improvement of 14% in speed-tracking accuracy and 6.8% in computational efficiency.

As the torque density of traction motors for electric vehicles (EVs) increases, winding technology with a large conductor area, such as hairpin winding, is widely used. However, it has a disadvantage of large AC copper loss affected by the skin and proximity effect. Therefore, the AC copper loss should be considered for deriving characteristics of interior permanent magnet synchronous motors (IPMSMs). This article deals with the maximum torque per ampere (MTPA) and flux-weakening control characteristics of the IPMSM considering AC copper loss. As the AC copper loss is caused by armature and field excitation, a separation process of AC copper loss by each cause is proposed. By using the process, the separated AC copper loss can be analyzed according to the current vector and rotational speed. However, it is inefficient to calculate the AC copper loss according to rotational speed using transient analysis. Therefore, a computationally efficient method of calculating AC copper loss based on magneto-static analysis is presented. In addition, advanced <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d, q</i> -axis equivalent model considering AC copper loss is proposed to analyze MTPA and flux-weakening control characteristics of IPMSM. By using the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d, q</i> -axis equivalent model, the IPMSM can be designed considering the AC copper loss efficiently and accurately.

According to the recent study, most of the mathematical model based motor efficiency optimized control schemes ignore the derivative terms of machine parameters with respect to the current angle. Therefore, even though the accurate machine parameters are known, these control schemes cannot calculate the accurate efficiency optimized operation points. Due to the machine parameter nonlinearity and harmonics, these derivative terms are difficult to be obtained online, which cause great difficulties in achieving accurate maximum torque per ampere (MTPA) control. To solve the above issues, in this article, an extended virtual signal injection control scheme is proposed. The proposed control scheme can automatically compensate for the MTPA control errors caused by parameter variations and achieve accurate MTPA control online. The proposed control method is demonstrated by both simulations and experiments under various operating conditions on prototype interior permanent magnet synchronous machine drive systems.

This paper proposes a high-precision mathematical modeling scheme for interior permanent magnet synchronous motors (IPMSMs), which gives full consideration to the saturation and cross-coupling influence based on the finite element analysis (FEA). Firstly, the IPMSM model is built in ANSYS/Maxwell to acquire the variable stator inductance and flux linkage parameters under various kinds of working conditions. Secondly, the obtained d-axis inductance, q-axis inductance, and rotor flux linkage are further calculated, processed, and pre-stored in three two-dimensional (2-D) look- up-tables (LUTs). Thirdly, the IPMSM model is built in MATLAB/Simulink based on three established tables. Finally, by looking up the three tables according to the real-time d-axis and q-axis currents, the IPMSM system can be simulated under different working conditions for various control methods. With the developed high-precision FEA-based mathematical modeling scheme, the simulation results will be more accurate and the simulation process will be more efficient with significant time savings and better dynamic performance. To validate the effectiveness of the proposed modeling scheme, a Space Vector Pulse Width Modulation (SVPWM) control system with maximum torque per ampere (MTPA) and flux-weakening (FW) control as well as feed-forward decoupling control is built based on a 15kW IPMSM prototype.

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.

An improved algorithm for MTPA (Maximum Torque Per Ampere) and Field Weakening operation which is suitable for implementation with Field Oriented Control, has been proposed for the Synchronous Reluctance motor (SynRel) for high dynamic performance. The proposed method overcomes the problem of excessive current flow into the machine while generating the d-axis and q-axis current commands independently. At the same time to operate the inverter in the linear modulation region (0≤m≤1) to minimize the output torque ripple. The proposed method helps to attain MTPA operation below the base speed to operate with the rated load and a fast speed response in Field Weakening mode. The validity and efficacy of the proposed algorithm is verified by simulation in MATLAB and SIMULINK.