Torque Control

This book is the result of inspirations and contributions from many researchers, a collection of 9 works, which are, in majority, focalised around the Direct Torque Control and may be comprised of three sections: different techniques for the control of asynchronous motors and double feed or double star induction machines, oriented approach of recent developments relating to the control of the Permanent Magnet Synchronous Motors, and special controller design and torque control of switched reluctance machine

Advances in the Field of Electrical Machines and Drives

Electrical machines and drives dominate our everyday lives. This is due to their numerous applications in industry, power production, home appliances, and transportation systems such as electric and hybrid electric vehicles, ships, and aircrafts. Their development follows rapid advances in science, engineering, and technology. Researchers around the world are extensively investigating electrical machines and drives because of their reliability, efficiency, performance, and fault-tolerant structure. In particular, there is a focus on the importance of utilizing these new trends in technology for energy saving and reducing greenhouse gas emissions. This Special Issue will provide the platform for researchers to present their recent work on advances in the field of electrical machines and drives, including special machines and their applications; new materials, including the insulation of electrical machines; new trends in diagnostics and condition monitoring; power electronics, control schemes, and algorithms for electrical drives; new topologies; and innovative applications

Control of a fractional-slot, concentrated-wound interior permanent magnet generator for direct-drive wind generation applications

This thesis assesses improvements to two types of control for a novel interior permanent magnet (PM) synchronous generator with fractional-slot, concentrated-wound stator designed for direct-drive wind energy conversion. The two control techniques assessed are a) field oriented control using a back-to-back converter arrangement and b) a current controller with a rectifier-connected boost converter. These were chosen to understand the potential and the limitations of the generator and its control. Modifications to the control techniques are proposed to improve the generator efficiency, the dynamic performance in the flux-weakening range and the torque ripple performance. The adequacy of the distributed-wound PM synchronous machine model for steady-state and dynamic control of this generator was experimentally validated under field oriented control using a back-to-back converter connected to the grid. The effectiveness of the existing current trajectory controls on the efficiency of the new generator was evaluated. A new flux-prioritized maximum torque per ampere technique which is independent of speed-dependent predefined trajectories was introduced, and a similar efficiency improvement was gained as the conventional loss minimization method in the partial load range. Thus, the control model validation and efficiency imrpovement of the new generator are the primary contributions. The dynamic performance of the generator, directly driven by a non-pitchable wind turbine emulator was investigated from cut-in speed to cut-out speed using maximum power point tracking and then constant power control above rated speed. A significant contribution was done in the power control above base wind speed that was achieved by utilizing the extended flux-weakening capability of the machine with its wide constant power-speed range. High torque ripple was observed when operated with a rectifier and boost converter using boost converter inductor current control. A new direct torque control technique using a machine rotor position based torque estimator was proposed to minimize this torque ripple. Eventhough the reduced torque ripple is still higher than that with back-to-back converter, the achieved ripple reduction is significant. The control of generator speed under each method is also demonstrated. Although the new method gives a faster speed dynamics than the conventional method, it shows slower speed response than that of back-to-back converter control. However, the significance of the study using a diode rectifier-connected boost converter control is highlighted with the achieved torque ripple minimization and performance enhancement of the generator. This study is expected to open new investigations in flux-weakening control of the PM generators using rectifier-connected boost converter. In this thesis, back to back converter control is demonstrated in order to optimally control the novel generator under the field oriented control, energy efficient current control and power control together with voltage control operating above rated speed. Torque ripple minimization of the generator is also presented when used with a diode rectifier-connected boost converter control

Performance Evaluation of a Cascaded H-Bridge Multi Level Inverter Fed BLDC Motor Drive in an Electric Vehicle

The automobile industry is moving fast towards Electric Vehicles (EV); however this paradigm shift is currently making its smooth transition through the phase of Hybrid Electric Vehicles. There is an ever-growing need for integration of hybrid energy sources especially for vehicular applications. Different energy sources such as batteries, ultra-capacitors, fuel cells etc. are available. Usage of these varied energy sources alone or together in different combinations in automobiles requires advanced power electronic circuits and control methodologies. An exhaustive literature survey has been carried out to study the power electronic converter, switching modulation strategy to be employed and the particular machine to be used in an EV. Adequate amount of effort has been put into designing the vehicle specifications. Owing to stronger demand for higher performance and torque response in an EV, the Permanent Magnet Synchronous Machine has been favored over the traditional Induction Machine. The aim of this thesis is to demonstrate the use of a multi level inverter fed Brush Less Direct Current (BLDC) motor in a field oriented control fashion in an EV and make it follow a given drive cycle. The switching operation and control of a multi level inverter for specific power level and desired performance characteristics is investigated. The EV has been designed from scratch taking into consideration the various factors such as mass, coefficients of aerodynamic drag and air friction, tire radius etc. The design parameters are meant to meet the requirements of a commercial car. The various advantages of a multi level inverter fed PMSM have been demonstrated and an exhaustive performance evaluation has been done. The investigation is done by testing the designed system on a standard drive cycle, New York urban driving cycle. This highly transient driving cycle is particularly used because it provides rapidly changing acceleration and deceleration curves. Furthermore, the evaluation of the system under fault conditions is also done. It is demonstrated that the system is stable and has a ride-through capability under different fault conditions. The simulations have been carried out in MATLAB and Simulink, while some preliminary studies involving switching losses of the converter were done in PSIM

Sensorless vector control of surface mounted permanent magnet machines without restriction of zero frequency

Permanent magnet motors have a series of characteristics that make them attractive for the use in industrial drives: low maintenance, high dynamics, small size and mass to power ratio. In particular its higher efficiency means that permanent magnet synchronous motors may be used instead of electro-magnetically exited motors (such induction machines or commutator DC motors) in applications where the energy savings compensate the higher initial cost. Nevertheless, the need for a shaft mounted position measurement to perform the orientation of the control of the synchronous machine is of concern, because it increases the total drive cost and reduces reliability. In this work the sensorless vector control of a surface mounted permanent magnet machine is presented. The emphasis is in the control at low and zero speed, including position control, by means of saturation saliency tracking. Two different strategies for rotor position detection used in salient synchronous machines and in induction machines are analysed. These are hf voltage injection in the stationary, stator, reference frame of the machine (α-ß injection) and hf voltage injection on the estimated rotor axis (so called d-axis or pulsating injection). These two methods are optimised for its application to the surface mounted PM machine. The small magnitude of the saliency present difficulties and disturbances are significant. A commissioning based method (SMP) is used for enhanced rotor position estimation by the α-ß rotating injection. The two methods are implemented on a 4 kW experimental rig and the sensorless controlled results are compared and discussed. A hybrid structure combining the saliency tracking method with a flux-observer is also presented and provides sensorless control capability over the whole speed range

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

PSIM-Based Hardware and Software Design of an Inverter-Fed Permanent Magnet Synchronous Motor

Master's thesis Renewable Energy ENE500 - University of Agder 2018The purpose of this research is to design a PSIM based controller for an inverter-fed Permanent Magnet Synchronous Motor (PMSM). The dimensioning and assembly of the controller are presented. The control algorithm used for the PMSM is Field Oriented Control (FOC). The report includes the theory of the control algorithm and its design. A PSIM based model is designed with the dimensioned components to analyse the behaviour of the controller. The model gives the opportunity of tuning the controller and verifying it with simulations. The model is then converted to be SimCoder compatible, enabling the simulation to be generated into a code. A Digital Signal Processing (DSP) development board is provided by Powersim Inc. The generated code is imported to the DSP, enabling it to run the controller. Similar behaviour is observed when comparing the test results with the simulations. When simulating the controller with the PMSM, all reference speeds are reached with a maximum deviation of 0:42%. Using PSIM proved to be an intuitive and educational way of designing the motor controller