This article discusses the maximum torque per ampere (MTPA) control of synchronous motors, which have become an indispensable part of highly efficient motor drives. It explains the nature of torque produced by synchronous motors, ways to find its maximum and algorithms to operate at this point, despite changes of loads and motor parameter variations. The authors propose a classification of the MTPA methods, based on the features of each algorithm or group of similar methods. They demonstrate the conventional control scheme and discuss the modifications necessary for the implementation of each method. This article reviews existing MTPA control algorithms, discusses their pros and cons, and suggests possible areas of usage for each group of methods. The authors of the article share their vast experience in the industry and research aspects, which were obtained by developing industrial, commercial, traction, and military drives, and report on their views on the perspective of each method taken into consideration.

This paper proposes a high-performance speed measurement method for variable speed electric drives using incremental encoders. It is based on the well-known constant elapse time (CET) method. However, the principle of speed estimation is changed from event driven to ready on demand. This helps to remove the jitter effect, caused by the asynchronous nature of the CET method, and make the speed estimation time constant regardless of the current speed. The proposed method can be implemented on modern motion control microcontrollers. Experimental results using a vector controlled Permanent Magnet Synchronous Motor (PMSM) are provided to confirm the performance of the proposed algorithm and the improvements with respect to conventional methods. Synchronous CET method of speed estimation allows to double the accuracy compared to the original CET method for the same behavior of the speed loop, or to increase the speed response time twice for the same accuracy.

This paper presents robust self-tuning maximum torque per ampere (MTPA) control algorithm for an interior permanent magnet synchronous motor (IPMSM) drives. Proposed algorithm utilizes conventional control scheme, where speed controller produces stator current command signal for the MTPA block. That block decomposes commanded current Is into its components along direct and quadrature axes id and iq respectively, which are used as a current commands for the current control loops. MTPA angle gamma, which is used for the decomposition is defined by the MTPA tuning algorithm, which continually varies that angle trying to find the one which provides the minimum of stator current at the given load torque.

This paper proposes an adaptive maximum torque per ampere (MTPA) control algorithm for interior permanent magnet synchronous motor (IPMSM) drives. This algorithm is insensitive to motor parameters variation due to operating conditions that is important for systems, which prioritizes reliability and efficiency. The proposed algorithm is designed to improve conventional control schemes, where the output of the speed controller is the commanded quadrature current and direct current is calculated using an MTPA equation. However, in distinction from the conventional MTPA approach, the proposed algorithm does not use any motor parameters. It implements a seeking technique and continuously varies the stator current phase angle while trying to minimize the magnitude of the current. The main contribution of this paper is the development of the method to overcome the main disadvantage of seeking algorithms – the necessity of stable disturbances at the consecutive measurement intervals. This paper adopts the seeking technique for the operation with the load torque varying over mechanical revolution, which is typical for many applications such as compressors, washing machines, robots, mechanical manipulators, servodrives, etc., The feasibility of the proposed algorithm is proven with experimental results shown and described in the corresponding section.

This article describes the next step in the development of the home appliance motor drive-the elimination of the electrolytic dc-link capacitor and the substitution of one with a small film. A small film capacitor increases total device reliability and improves the spectrum of the input current so the power factor corrector (PFC) used to satisfy existing standards on harmonic current emission can be omitted, which decreases the size and cost of the appliances. This article also proposes simple modifications to the standard vector control scheme, making operation with pulsating dc-link voltage possible.

Interior permanent magnet synchronous motor (IPMSM) efficiency can be improved by using maximum torque per ampere control (MTPA). MTPA control utilizes both alignment and reluctance torques and usually requires information about the magnetization map of the electrical machine. This paper proposes an adaptive MTPA algorithm for sensorless control systems of IPMSM drives, which is applicable in industrial and commercial drives. This algorithm enhances conventional control schemes, where the output of the speed controller is the commanded stator current and the direct current is calculated using an MTPA equation; therefore, it can be easily implemented in the previously developed drives. The proposed algorithm does not use any motor parameters for the calculation of the MTPA trajectory, which is important for systems operating in changing environmental conditions, because motor inductances and flux linkage strongly depend on the stator current and the rotor temperature, respectively. The proposed algorithm continuously varies the current phase and in such a way it tries to minimize the magnitude of the stator current at the applied load torque. The main contribution of this paper is the development of a technique to overcome the main disadvantage of seeking algorithms–the necessity of a precision information about the rotor position. The proposed method was verified experimentally.