Kaveh Malekian

An optimal current vector control for synchronous reluctance motors incorporating field weakening

In this paper, a new approach to the synchronous reluctance motor control that ensures the production of maximum torque over the entire field weakening region is presented. In other words, this paper presents an optimal control scheme for wide speed range operation of synchronous reluctance motor drives, where current vector is directly controlled. The proposed scheme possesses some attractive features when compared to the conventional current-controlled drives. The scheme incorporates optimal control strategies, such as the maximum torque per ampere operation in constant torque region and maximum torque per flux operation in field-weakening region, and operates the drive within the voltage and current limits of the motor/inverter. The control scheme has been verified by simulation tests with a prototype synchronous reluctance motor.

An optimal direct thrust force control for interior Permanent Magnet Linear Synchronous Motors incorporating field weakening

This paper presents an optimum direct thrust force control for interior permanent magnet linear synchronous motor (PMLSM) over wide velocity range in which the maximum thrust force per ampere (MTPA) strategy is used below the base velocity and field weakening strategy is used above the base velocity. Using MTPA strategy, copper losses is minimized in constant force region, and using field weakening strategy, maximum capacity of motor is utilized in constant power region. The proposed scheme incorporates all the optimal strategies and operates the drive within the voltage and current limits of the motor/inverter. Simulation results for a prototype interior permanent magnet linear synchronous motor demonstrate that the MTPA and field weakening strategies can be successfully implemented for direct thrust force controlled PMLSM drives.

Problems associated with parallel performance of high current semiconductor switches and their remedy

The development in the technology of power semiconductors results in their application in FACTS devices, static switches, hybrid switches, HVDC, and high power converters. Since the nominal current of such devices does not satisfy high power applications, in order to increase the current ratings, switches should be paralleled. In this paper, the behavior of the paralleling of devices such as diodes, IGBTs, MOSFETs, and BJTs are discussed. A method is presented to improve parallel performance of high current semiconductors as well. The validity of proposed method is investigated in both simulation and implementation.

A Genetic Based Fuzzy Logic Controller for IPMSM Drive Over Wide Speed Range

A radial basis function network for online tuning of a genetic based fuzzy logic controller for interior permanent magnet synchronous motor drive over wide speed range is presented in this paper. Initially different operating conditions are obtained based on motor dynamics incorporating uncertainties. At each operating condition, a genetic algorithm is used to optimize fuzzy logic controller parameters in closed- loop vector control scheme. In the other words, the genetic algorithm finds optimum input and output scaling factors and optimum number of membership functions. This optimization procedure is utilized to obtain the minimum speed deviation, minimum settling time, and zero steady-state error. A radial basis function network is used for online tuning of a fuzzy logic controller parameters (input and output scaling factors and number of membership functions) to ensure optimum drive performance under different disturbances.

A genetic based fuzzy logic controller for direct torque controlled IPMSM drives over wide speed range

The main theme of this paper is to present a novel controller, which is a genetic based fuzzy Logic controller, for interior permanent magnet synchronous motor drives with direct torque control. A radial basis function network is used for online tuning of the genetic based fuzzy logic controller. Initially different operating conditions are obtained based on motor dynamics incorporating uncertainties. At each operating condition, a genetic algorithm is used to optimize fuzzy logic parameters in closed-loop direct torque control scheme. In other words, the genetic algorithm IInils optimum input and output scaling factors and optimum number of membership functions. This optimization procedure is utilized to obtain the minimum speed deviation, minimum settling time, and zero steady-state error. The control scheme has been verified by simulation tests with a prototype interior permanent magnet synchronous motor.

Reliability consideration for a high power zero-voltage-switching flyback power supply

In this study, a high power zero-voltages-witching flyback power supply is presented. An appropriate efficiency is achieved by designing an auxiliary circuit for reduction of dynamic losses in the power switch. Due to the importance of reliability in the switch mode power supplies, reliability assessment is discussed for this zero-voltage-switching flyback converter in details. This paper illustrates that flyback topology has suitable reliability in the high power applications. Although by implementing auxiliary circuit in this topology, softer switching for the main switch is achieved, simplicity of the flyback converter is reduced. As a result, the control and power stages are more complicated. Also, reliability calculations demonstrate that due to soft switching and, consequently, reduction of power switch stresses, zero-voltage-switching flyback has a proper failure rate.

Performance improvement of direct torque controlled interior permanent magnet synchronous motor drive by considering magnetic saturation

The influence of magnetic saturation on the maximum torque per ampere strategy in constant torque region and field weakening strategy in constant power region for a direct torque controlled interior permanent magnet synchronous motor drive are discussed in this paper. In other words, by considering magnetic saturation, all optimal strategies and motor-inverter limitations are derived in the T - |psis| plane to apply in the direct torque control method. These strategies that take magnetic saturation into account and determine the optimal torque and flux commands are derived and implemented in direct torque control method. Simulation results on a prototype interior permanent magnet motor are included to validate the usefulness of the work.

Reliability consideration for a high power single switch flyback power supply

In this paper, a high power single switch flyback power supply is presented. Performance of this power supply in continuous conduction mode is investigated in implementation. An appropriate efficiency is achieved by designing a proper snubber circuit. With regard to the importance of reliability in switch mode power supplies, reliability consideration is discussed for this high power flyback in details. This paper demonstrates the flyback topology has suitable failure rate in high power applications because it has only one power switch.

Performance evaluation of electric power steering with IPM motor and drive system

As the development of microprocessors, power electronic converters and electric motor drives, electric power steering system which uses an electric motor came to use a few year ago. Electric power steering systems have many advantages over traditional hydraulic power steering systems in engine efficiency, space efficiency, and environmental compatibility. This paper deals with design and optimization of an interior permanent magnet motor for power steering application. Direct search method is used for optimization. After optimization and finding motor parameters, an interior permanent magnet motor and drive with mechanical parts of electric power steering system are simulated and performance evaluation of system is done.

Improved direct torque control for induction machine drives using fuzzy logic and particle swarm optimization

Here, a new fuzzy direct torque control algorithm for induction motors is proposed. As in the classical direct torque control, the inverter gate control signals directly come from the optimum switching voltage vector look-up table, the best voltage space vector selection is a key factor to obtain minimum torque and flux ripples. In the proposed approach the best voltage space vector is selected using a new fuzzy method. A simulation model is built up and the torque and flux ripples of basic direct torque control and the proposed method are compared. The simulation results show that the torque and flux ripples are significantly decreased and in addition, the switching frequency can be fixed.