Christos Mademlis

Loss minimization in vector-controlled interior permanent-magnet synchronous motor drives

An efficiency optimization method for vector-controlled interior permanent-magnet synchronous motor drives is presented. Based on theoretical analysis, a loss minimization condition that determines the optimal d-axis component of the armature current is derived. Selected experimental results are presented to validate the effectiveness of the proposed control method.

Optimal efficiency control of switched reluctance generators

This paper investigates the problem of optimal control for accomplishing maximum energy conversion in switched reluctance generators. A controller that determines the optimal turn-on and turn-off angles in the mode of single-pulse operation is proposed. The structure of the controller and its implementation are simple, since the knowledge of the magnetization curves is not required. The suggested generator drive operates in a wide speed range and provides constant dc-link voltage at a desired value, with maximum energy efficiency. Simulation and experimental results are presented to validate the effectiveness and the resulting improvements of the proposed control scheme.

Optimal efficiency control strategy for interior permanent-magnet synchronous motor drives

In this paper, the problem of efficiency optimization in vector-controlled interior permanent-magnet (PM) synchronous motor drives is investigated. A loss model controller is introduced that determines the optimal d-axis component of the stator current that minimizes power losses. For the implementation of the suggested controller, the knowledge of the loss model is not required since an experimental procedure is followed to determine its parameters. Furthermore, it is shown that the loss model of the interior PM motor can be used as a basis for deriving loss minimization conditions for surface PM synchronous motors and synchronous reluctance motors as well. Experimental results of an interior PM motor are presented to validate the effectiveness of the proposed method and demonstrate the operational improvements.

Performance optimization in switched reluctance motor drives with online commutation angle control

The problem of performance optimization in current controlled switched reluctance motor (SRM) drives is investigated. Two controllers are proposed that determine the optimal turn-on and turn-off angles, respectively, for improving motor efficiency and torque ripple. The suggested controllers are simple, do not affect the complexity of the drive, and are easily implemented since the knowledge of torque-angle-current characteristics or magnetization curves is not required. The proposed control scheme is demonstrated on a prototype experimental system.

Loss minimization in surface permanent-magnet synchronous motor drives

The loss minimization in surface permanent-magnet synchronous motor drives is investigated. Based on theoretical analysis, a loss model controller is introduced to specify the optimal air-gap flux that minimizes losses. Theoretical results are verified experimentally. The proposed loss model controller is simple and does not adversely affect the cost and complexity of the drive. Implementation of the loss model controller does not require knowledge of the loss model. The suggested loss minimization method can be applied both in V/f- or current-controlled schemes.

Optimizing performance in current-controlled switched reluctance generators

The problem of choosing the firing angles for accomplishing optimal performance in current-controlled switched reluctance generators (SRGs) is examined. The optimal performance is reached with the correct balance between the criteria of high efficiency and low torque ripple. The concept of the method is based on the optimal control of turn-on and turn-off angles according to electrical load requirements and depending on rotor speed and dc-link voltage. A simple controller is proposed that on-line determines the optimal firing angles. The suggested controller does not affect the complexity of the drive and the knowledge of the magnetization curves is not required for its implementation. Simulation and experimental results are presented to validate the resulting improvements of the proposed control scheme.

On Considering Magnetic Saturation with Maximum Torque to Current Control in Interior Permanent Magnet Synchronous Motor Drives

The influence of magnetic saturation on maximum torque to current controlled interior permanent magnet synchronous motor drives is discussed in this paper. A maximum torque to current condition that takes into account magnetic saturation and determines the optimal d-axis current is derived. For the implementation of the proposed controller, an experimental procedure is used to adjust its parameters, therefore, the knowledge of the exact motor model is not required. Selected experimental results are presented to verify the theoretical considerations and to confirm the high performance of the suggested controller.

Gain-Scheduling Regulator for High-Performance Position Control of Switched Reluctance Motor Drives

The problem of high-precision position control in switched reluctance motor (SRM) drives is investigated in this paper. Advanced proportional-integral and proportional-differential controllers for speed and position controls, respectively, are adopted. A gain-scheduling technique is adopted in the speed controller design for providing high dynamic performance and precise position control. In order to improve the set-point tracking, a low-pass filter is included in the position controller. The proposed four-quadrant control scheme is based on the average torque control method. The turn-on and turn-off angles are online determined through simple formulas so as to reduce the torque ripple at an acceptable level over a wide speed range. This is important since the position precision is highly influenced from the motor torque ripple. Experimental results of the SRM dynamic response are presented to verify the theoretical considerations and to demonstrate the effectiveness of the proposed control scheme.

Optimization of single-phase induction Motors-part I: maximum energy efficiency control

This work investigates the problem of efficiency optimization in capacitor-run single-phase induction motors. The double-revolving-field concept is employed in the theoretical analysis and a relation between the main and auxiliary stator currents is derived that accomplishes optimal efficiency under constant torque operation. A triac-based drive with an optimal efficiency voltage controller is proposed. The controller is easily implemented since an experimental procedure is used for adjusting its parameters. Moreover, the proposed control scheme satisfies all of the prerequisites of simplicity, reliability, and cost-effectiveness that are imposed by the utilization of a single-phase motor. Several experimental results are presented to validate the effectiveness of the proposed efficiency optimization control method.

High-Efficiency Control for a Wind Energy Conversion System With Induction Generator

In this paper, an improved efficiency control scheme for wind energy conversion systems (WECSs) with squirrel cage induction generators is proposed. Thus, the power harvesting from the WECS is increased and additionally expansion of the exploitable wind speed region toward the lower speed range is accomplished. The generator is connected to the power grid by means of two space-vector-controlled back-to-back converters. A minimum ohmic loss (MOL) controller is introduced in order to minimize the generator resistive loss that is accomplished by adjusting the d-axis stator current according to torque conditions. The implementation of the proposed controller is easy and cost effective because neither additional control signals nor the knowledge of the generator loss model is required. The effectiveness of MOL controller and its successful cooperation with two types of maximum power point tracking (MPPT) controllers, which are employed to maximize the wind turbine output power, are experimentally verified. The MPPT controller is implemented by using an adaptive search control and a fuzzy-logic-based control technique, since both are independent of wind turbine characteristics and widely used. Selective experimental results are presented to demonstrate the resulting improvements of the suggested control scheme.