Sensorless Speed Control of IPMSM Using Sliding Mode Observer Based on Active Flux Concept Fayza Boussekra, Abdessalam Makouf Department of Electrical Engineering, LSPIE Laboratory, Faculty of Technology, University of Mostefa Ben Boulaïd, Batna 2, Algeria Corresponding Author Email: fayza.boussekra@gmail.com; a_makouf@yahoo.fr https://doi.org/10.18280/mmc_a.931-401 ABSTRACT Received: 3 August 2020 Accepted: 7 December 2020 This paper proposes a new speed and position sensorless control method of Interior permanent magnet synchronous motors (IPMSM) using sliding mode observer based on Active Flux concept. First, a new description of IPMSM dynamic model in the stationary reference frame using active flux concept is proposed. The model obtained suits for both SPMSM and IPMSM in the stationary reference frame, Therefore, all that sensorless controls proposed for SPMSM can be directly and easily applied to IPMSM. Secondly, from the measurement of the voltages and the currents, a new analysis of the observability property is developed. Then, the sliding mode observer (SMO) structure and its design method are described in the stationary reference frame by using the active flux equation. A “chattering” phenomenon is reduced by using this technique. The stability of the proposed SMO was verified using the Lyapunov function. The speed and position of the IPMSM are estimated based on back EMF which are related to the active flux. Moreover, the zero d-axis current control strategy is used to control the IPMSM. Finally, the proposed method on the proposed model has been simulated and tested to show the effectiveness of the proposed scheme. Keywords: active flux, Interior permanent magnet synchronous motor, Sensorless control, Sliding mode observer 1. INTRODUCTION The importance of high efficiency at low speed and high torque/power density make many industrial applications using permanent magnets synchronous motors (PMSM), especially interior permanent magnet synchronous motors (IPMSM) because it has many advantages compared to the other types of motors in efficiency and power density [1-3]. For feedback control, the knowledge of position and rotor speed are necessary. Thus, speed sensors such as the encoders or the resolvers are utilized. In order to reduce the motor size, the hardware complexity, cost, and to improve robustness and reliability of the drive system the sensorless vector control of IPMSM has been proposed [4-6]. Two approaches of sensorless control of IPMSM can be cited. The first approach uses the excitation at high frequency to detect saliency difference between direct axis-d and quadrature axis-q. This method gives good performances at low speeds range but increase the complexity of sensorless control system and induces undesirable effects on the motor performances as the increasing of losses [7-9]. The second approach using the estimation of the back EMF value deduced from the integration of the total flux linkage on the stator phase circuits is simple. This approach is very adapted for the IPMSM drive system allowing to achieve good performances at medium and high speeds operating region [10-12]. However, these methods can fail at very low and zero rotating speed since the IPMSM dynamic model is quite complex, nonlinear, coupled and also the parameters are most often not known exactly during operating system [13]. To enhance the performance of the sensorless operation at low speed, several sensorless control methods has been developed. Online parameter estimation method is introduced by Chen [4]. It consists to minimize the effects of parameter variations using a new IPMSM mathematical model, in [14] a robust sensorless control with respect to the inverter irregularities, using of an on-line stator resistance identification method is proposed. the authors propose by Inoue et al. [15] a sensorless-control method based on the extended (EMF) concept for improving performance such as the operating speed range and the accuracy of position estimation. Therefore, in order to simplify the IPMSM dynamic model and also make it more accessible to automated design technique. For instance, the concept of extended back- electromotive force (EMF) has been introduced by Chen et al. [16]. Indeed, it was the first attempt that has developed a new mathematical model for PMSM, suitable for both SPMSM and IPMSM and also valid for Reluctance Synchronous Motors (RSM). For the same purpose, Boldea et al. [17] propose a simple and efficient model of IPMSM based on the active flux concept. Using this concept, the IPMSM dynamic model can be described as an SPMSM model in the stationary reference frame (α, β) and also, makes it accessible for control design. The “active flux” concept which “turns all salient-pole rotor AC machines into fictitious non-salient-pole machines” is defined as the torque-producing virtual flux which multiplies the iq current component on the d axis in the electromagnetic torque equation of ac machines in the rotating reference frame (d, q). Another approach that can be taken to simplify the model of IPMSM called a fictitious permanent-magnet flux concept which was proposed by Koonlaboon [18]. Actually, there is no Modelling, Measurement and Control A Vol. 93, No. 1-4, December, 2020, pp. 1-9 Journal homepage: http://iieta.org/journals/mmc_a 1