Continuous Control Set Model Predictive Torque Control With Minimum Current Magnitude Criterion for Synchronous Motor Drives

Abstract

To achieve high efficiency and dynamics in electric drive applications, it is necessary to have accurate torque control. This is typically accomplished through a current regulator that is fed by references generated by various open-loop control strategies, in order to obtain the desired torque. As an alternative, this work presents a model predictive torque control. Starting from the torque reference, the algorithm generates optimal voltage references to the inverter-fed synchronous motor drive while working at maximum efficiency and considering the motor current limit. This feature is achieved by combining two different norms in the cost function. The electromagnetic torque is estimated from the measured currents and an accurate magnetic model of the motor. According to the paradigm of the more autonomous drives, an important feature is that the algorithm requires only knowledge of the motor model. This means that a tuning procedure for control weight is no longer required as analytically discussed in this work. Experimental validation of the proposed technique is performed on a test rig featuring an anisotropic permanent magnet motor in different dynamic operation, including flipping from the motor nominal working point to the generator one. Index Terms-Continuous control set, model predictive control, permanent magnet synchronous motor (PMSM), torque control. NOMENCLATURE xLower-case bold letter stands for vector. XUpper-case bold letter stands for matrices. . = Stands for definition.

FCS-MPC Based on Dimension Unification Cost Function

“…where k denotes the control cycle sequence and n ai {i∈ [1][2][3][4]} represents the number of switching actions for the power switching device in phase-a during the first control cycle. Then, the average switching frequency of the inverter is defined as f e :…”

“…Finite Control Set Model Predictive Control (FCS-MPC) has gained widespread application in the fields of power electronics and power transmission, owing to its advantages in time-domain control, multi-objective optimization, and nonlinear processing [1][2][3]. Notably, the three-level Neutral Point Clamped (NPC) inverter finds extensive application in variable frequency speed control systems for medium-voltage high-power motors, attributed to its advantages including multiple output levels, low voltage withstand of switching devices during off states, and high efficiency [4].…”