Current control method with control inputs in polar coordinates for SPMSM based on linearized model

Abstract

SPMSMs (Surface Permanent Magnet Synchronous Motors) are employed for many industrial applications. For quick torque response under voltage limit, voltage phase control method had been proposed. However, it needs to switch the mode of controller. This paper proposes a flux-weakening control method for SPMSM using control inputs in polar coordinates to reduce the number of mode transition. This control method is designed with a precise plant model. In addition, the authors investigate controller design using control inputs in polar coordinates instead of d-axis and q-axis voltage within voltage limit.

High Response Torque Control of IPMSM Using State Feedback Control Based on n-t Coodinate System

“…Manipulated variables in the proposed control are voltage amplitude V a and voltage phase ; therefore, numerical model for manipulating voltage amplitude and phase in d-q coordinates can be derived by substitution of Equation (2) into Equation (1), and linearization around equilibrium point. Thus obtained results are shown below in Equation (3) through Equation (7).…”

High‐Response Torque Control of IPMSM Based on a New Coordinate System Suitable for Voltage Amplitude and Phase Control

“…(4), (6), and (14), and therefore these variables are used to design the controller. Particularly, transfer function ΔP n1 (s) from manipulated variable V a in voltage amplitude control to controlled variable i n is used to design C v (s).…”

“…ΔP n1 (s) varies with δ o and λ as can be found from Eqs. (4), (6), and (14), and therefore these variables are used to design the controller. In this study, design value of angular frequency in voltage amplitude control is set the same as design value ω c in voltage phase control.…”

“…Voltage phase control has some problems, such as high-response design is difficult, and control switching is necessary. Some solutions have been proposed with regard to these problems, such as high-response design method using a motor model for voltage phase control [5], and torque control method in which voltage phase control is supplemented with voltage amplitude control so that control switching is not needed [6]. In the latter case, however, high-response torque control cannot be realized because of mutual interference between voltage amplitude control and voltage phase control.…”

“…Microscopically, n-axis current is not affected by voltage phase control, which allows performing voltage amplitude control and voltage phase control without mutual interference. When voltage amplitude/phase control is performed in d-q coordinates, a complex algorithm was required to deal with mutual interference [6,7]. In contrast, the proposed torque control is performed in n-t coordinates, which is free of the mutual interference, and therefore no complex algorithm is needed, and furthermore torque can be controlled without switching from linear range through voltage saturation range.…”