Combined vector and direct torque control methods for IPM motor drives using emotional controller (BELBIC)

This paper presents a modern control system for three phase high performance interior permanent magnet motor drives. The control system combines the advantages of vector control and direct torque control and overcomes some of the implementation drawbacks of either of the methods. The system uses a current control loop in connection with a switching table. A brain emotional learning based intelligent controller (BELBIC) is employed in the system which provides excellent performance under different operating conditions. BELBIC is based on the emotion processing mechanism in human's brain providing actions based on sensory inputs and emotional cues. A comprehensive evaluation of an IPM motor performance under the proposed control system proves the effectiveness of the system and its partial superiority over either vector control or direct torque control despite its relatively simple structure.

I. INTRODUCTION

Variable speed motors require fast, accurate and smooth performances over wide operating conditions in many industrial applications [1]–[3]. High performance AC motor drives have reached a high level of maturity that can meet the needed requirements by the two competing methods i.e. vector control (VC) and direct torque control (DTC) [1], [2]. Both methods include many different schemes now [1], [4]. Notwithstanding their similarities, VC and DTC are indeed different in the implementation. Also, the details of the motor drive performances, such as torque and flux pulsations and their accomplishment forms are quite different at least in the original VC and DTC schemes. Therefore, the principles of the methods are commonly regarded far apart. The differences of VC and DTC have mainly been the focus of comparative analyses reported in the literature [3]. Among AC machines, interior permanent magnet (IPM) motors have attractive features like mechanical robustness, smooth air gap, high flux weakening capability and high efficiency. These features allow the IPM motor drives to demonstrate high performance operation [1], [5]. VC and DTC both have been applied successfully to IPM motor drives [4]. VC benefits from current control loops and provides smooth motor operation while DTC enjoys attractive features such as minimal parameter dependency, fast dynamic response, and no requirement for mechanical rotor position sensor for the inner torque control loop [6]. However, VC needs rather complex PWM and DTC suffers from torque and flux pulsations and control problems at low speed and lack of direct current control.