Fixed Switching Period Discrete-Time Sliding Mode Current Control of a PMSM

Abstract

A fixed switching period sliding mode control (SMC) for Permanent Magnet Synchronous Machines (PMSMs) is presented. The aim of the paper is to design a SMC that improves the traditional PI based Field Oriented Control (FOC) transient response, as well as to reduce the switching frequency variations of the Direct Torque Control (DTC). Such SMC requires a decoupling method of the control actions, which also brings constant switching functions slopes. These constant slopes allow to calculate the required hysteresis band value to control the switching frequency. The digital implementation degrades the performance of the hysteresis comparator and as a consequence, the previously calculated band becomes inaccurate to regulate the switching frequency. In order to recover the analogue hysteresis band comparator performance, a predictive algorithm is proposed. Finally, a set of experimental results with constant switching frequency during a torque reversal and speed control tests are provided.

A Comparative Study of Terminal and Conventional Sliding-Mode Startup Peak Current Controls for a Synchronous Buck Converter

“…The sliding mode controllers are digitally implemented according to the technique proposed in [29]. The idea is to use a PWM module as a Set-Reset Flip-Flop, controlling the time instant at which the control signal commutates.…”

“…In order to keep the switching function within the hysteresis bands, the sampling of the control (T s = 1 µs) must be higher than the desired switching period (10 µs). Moreover, due to the delay produced by the computing time (700 ns), a simple switching function prediction algorithm was proposed, achieving a continouous time hysteresis comparator emulation (see [29] for details). A simulation of the technique is shown in the computation of ((7) or (14)) is made, the prediction is obtained as (23) states.…”

“…For the experimental evaluation, an implementation method that preserves the continuous time TSMC and CSMC dynamics in a digital implementation is applied [29]. That technique implements a digital emulation of a continuous time hysteresis comparator, where a pulse width modulator is used as a setreset flip flop.…”

A Review on Controlling Techniques for Permanent Magnet Synchronous Motor (PMSM) and Current State of the Art in the Research Area

“…The work of Repecho et al [43] discussed issues of the PI-based control system and aimed to achieve faster transient response through DTC mechanism. The results of this model give the best speed control and faster transient response.…”

A Novel Adaptive Neuro-Control Approach for Permanent Magnet Synchronous Motor Speed Control

“…A PMSM is a typical nonlinear and strongly coupled system, with unpredictable external disturbances, as well as internal parameter variations [2]. In recent years, various nonlinear control methods [3][4][5][6][7][8][9][10][11], such as fuzzy logic control, sliding mode control, neural network control, nonlinear optimal control, internal model control, adaptive control, have been used to meet the requirements of high reliability and performance in PMSM control [7][8][9][10]. The fuzzy logic control is successfully applied in the speed control of PMSMs [12,13].…”