Switching Regulation in the Control of 5-Phase Permanent Magnet Synchronous Motor Fed by 3×5 Direct Matrix Converter Muhammad Ishaq * , Yanbo Che, Kifayat Ullah Key Laboratory of Smart Grid of Education Ministry, Tianjin University, Tianjin 300072, China Corresponding Author Email: muhammadishaq1359@gmail.com https://doi.org/10.18280/ejee.230104 ABSTRACT Received: 6 October 2020 Accepted: 3 February 2021 Matrix converter is an AC-AC direct power converter comprising of an array of bi- directional switches. It does not require an intermediate DC-link and allows sinusoidal output waveforms with varying amplitudes and frequencies. The configuration of these bi- directional switches decides the number of inputs and outputs of the matrix converter. This research uses a direct matrix converter (DMC) as a phase-changing device that can convert a three-phase AC voltage into a 5-phase AC voltage. The DMC is modulated with the model predictive control algorithm. The output of DMC is fed to a five-phase permanent magnet synchronous motor (PMSM). The model predictive current control technique for DMC is carried out by developing a mathematical model of an input filter and PM motor used as a load. The predictive control of DMC results in sinusoidal output current, and it also enables the frequency variation in the output current. This frequency variation is useful in controlling the speed of the motor connected to the load. After controlling the 5- phase motor, the switching frequency regulation is done to observe its effect on the motor's stator current waveforms. Switching frequency regulation helps to limit the unnecessary switching of DMC. We developed a MATLAB-based Simulink model to study PMSM, and detailed results are presented. The results show that switching regulation can significantly reduce the switching frequency without compromising the current waveform quality. Keywords: direct matrix converter, model predictive control, switching regulation, PMSM 1. INTRODUCTION Direct MATRIX Converter (DMC) was first introduced by [1], and the authors proposed a scaler control (SC) technique for its operation. Over the years, DMC has created highlights because of its potential use in a wide range of power system applications such as power electronics and electrical and power engineering. DMC is composed up of bidirectional switches. The switches are arranged in m×n grid configuration [2]. In this m×n grid, m represents the columns, and n represents the number of rows. In other words, the columns denote the number of inputs, and the rows denote the number of outputs of DMC, as shown in Figure 1. Depending on the application, the number of bidirectional switches can be varied. A DMC can be connected in various configurations such as 1×3, 3×1, 3×3, 5×3, and 3×5, and so on. This paper uses a 3×5 configuration. DMC belongs to a class of power converters that directly transform AC waveforms without requiring an intermediate DC-link stage. In this type of converters, the input side is directly connected to the load side instead of the traditional back-to-back AC-DC-AC converters. In AC-DC-AC converters, the AC is first converted to DC then transformed into AC. Since it is a direct converter, hence the name Direct MC (DMC). DMC is composed of solid-state semiconductor bidirectional switches, for example, a TRIAC. These properties make DMC very compact in design and simple to use. A DMC can generate output voltages with varying amplitudes and frequencies, i.e., an output voltage can be obtained with a different frequency than the input voltage [3]. Additionally, it also generates a sinusoidal output current waveform. It operates with an asymptote unity power factor. Therefore, it has applications in the field of power systems such as reactive power control [4]. DMC allows the transfer of power in both directions, i.e., to and from the load to the electrical grid, making it a regeneration device. For example, if a permanent magnet synchronous machine (PMSM) is connected with a DMC, it can be operated both as a motor and a generator [5]. Due to these characteristics mentioned above, DMC can be widely used as a phase transformation system. DMC can play a vital role in multiphase power generation. Multiphase power generation has several advantages over a conventional 3-phase generation. For example, there is a reduction of phase losses in the multiphase generation system. The output power increases due to high power density. The five-phase power generators are relatively smaller in size compared to three- phase generators [6]. The contemporary structure of the electric power grid is mostly 3-phase; therefore, a phase conversion device is always required when the load requires more than three phases [7]. For example, if a five-phase generator is installed in a power system, then a 3x5 DMC converter can be used to connect it to a 3-phase grid. In the future, when the smart grid is implemented on a larger scale, the use of a 5-phase distributed generator will be widespread. Multiphase distributed generators have many advantages, such as greater fault tolerance capacity, improved long-term reliability, reduced torque ripple, reduced voltage distortion, and the smaller size DC-link. Likewise, a 3×5 DMC converter can be used when a European Journal of Electrical Engineering Vol. 23, No. 1, February, 2021, pp. 27-35 Journal homepage: http://iieta.org/journals/ejee