Field Weakening Control of Interior Permanent Magnet Synchronous Motor Employing Model Order Reduction

Various control strategies have been adopted for the field weakening control of the interior permanent magnet synchronous motors. Most of these either use the magnetic model parameters or utilize the approaches like the look up tables to minimize the effects of parametric sensitivity. The variation of the inductance values due to the magnetic saturation or the cross-coupling and fluctuation in the stator resistance and the permanent magnet flux due to the temperature difference can significantly affect the control performance especially at high speeds. In this thesis, the field weakening algorithm has been proposed that employs one of the model order reduction technique, i.e. orthogonal interpolation method. This technique obtained from reducing the order of the finite element model of the machine takes the stator current components as input and outputs the corresponding flux linkage components. At first, the control design was implemented utilizing the reduction technique that contained the motor parameters to test the validity of the orthogonal interpolation method in the field weakening operation. Thereupon, the technique was designed operating independent of any machine parameter that put into place the orthogonal interpolation method and its inversion for the references calculation. The simulink feature, ‘algebraic constraint’, was used in combination with the reduction technique to produce the required current components. The control techniques were implemented in the field oriented control scheme. The methods were at first tested through simulations in the MATLAB/Simulink environment and then the experiments were performed in the dSPACE laboratory for validity of the results. The results provided in the end confirm the feasibility of the approach used. The motor operates well in the field aweakening region and can operate in the wide speed range. The results also confirm that the approach operating independent of the machine parameters exhibit better control performance

Efficiency optimal control of interior permanent magnet synchronous motor / by Fasil Abera.

There has been a growing concern over energy consumption since the past decade mainly because of the soaring cost of energy and tight environmental laws and regulations. In this thesis a model based efficiency optimization for speed control of interior permanent magnet synchronous motor (IPMSM) is proposed to improve the efficiency of the motor drive which usually operates at different load and speed conditions. Recently, the IPMSM has been becoming popular due to some of its advantages such as high efficiency, high power density, low noise and robustness as compared to the conventional induction and other ac motors. Thus, the IPMSM is considered in this work. The proposed energy optimization algorithm is developed based on motor model. In order to minimize the controllable losses, the air gap flux level should be optimized. In an LPMSM the flux level can only be optimized by controlling the d-axis armature current as the field flux is supplied by the rotor permanent magnet. For the proposed work the vector control technique is used in order to achieve fast and accurate speed response, quick recovery of speed from any disturbance and insensitivity to parameter variations etc. A simulation model for the complete closed loop vector control of IPMSM incorporating the proposed energy optimization algorithm has been developed using Matlab/Simulink software. The performance of the drive has been tested extensively for different dynamic operating conditions such as sudden load, command speed and parameter changes. An efficiency gain of about 4% is obtained from the proposed optimization algorithm from simulation. After the satisfactory simulation results are found a realtime implementation of the complete drive system using DSP board (DS1104) for a laboratory 5 hp motor performed and the real time responses confirms with the simulation results as expected

Fuzzy logic based efficiency optimization of IPM synchronous motor drive

Interior permanent magnet synchronous motor (IPMSM) is highly appreciated by researchers in variable speed drive applications due to some of its advantageous features such as small size, high power density, simple maintenance, high output torque, high power factor, low noise and robustness as compared to the conventional IM and other ac motors. Although these motor drives are well known for their relatively high efficiency, improvement margins still exist in their operating efficiency. Particularly, the reduction of power loss for IPMSM still remains a challenge for researchers. Improvement of motor drives efficiency is important not only from the viewpoints of energy loss and hence cost saving, but also from the perspective of environmental pollution. The thesis presents development of a fuzzy logic based efficiency and speed control system of an IPMSM drive. In order to maximize the efficiency in steady state operation while meeting the speed and load torque demands a search based fuzzy efficiency controller is designed to minimize the drive power losses to achieve higher efficiency by reducing the flux. The air gap flux level can be reduced by controlling the d-axis armature current as it is supplied by rotor permanent magnet. In order for the drive to track the reference speed in transient operation another fuzzy logic based controller is designed to increase the flux depending on the speed error and its derivative. The torque component of stator current (q-axis component of stator current) is generated by fuzzy logic based speed controller for different dynamic operation depending on speed error and its derivative. In this work a torque compensation algorithm is also introduced to reduce the torque and speed fluctuations

Speed sensorless and MPPT control of IPM synchronous generator for wind energy conversion system

The popularity of renewable energy has experienced significant growth recently due to the foreseeable exhaustion of conventional fossil fuel power generation methods and increasing realization of the adverse effects that conventional fossil fuel power generation has on the environment. Among the renewable energy sources, wind power generation is rapidly becoming competitive with conventional fossil fuel sources. The wind turbines in the market have a variety of innovative concepts, with proven technology for both generators and power electronics interfaces. Recently, variable-speed permanent magnet synchronous generator (PMSG) based wind energy conversion systems (WECS) is becoming more attractive in comparison to the fixed-speed WECS. In the variable-speed generation system, the wind turbine can be operated at maximum power operating points over a wide speed range by adjusting the shaft speed optimally. This thesis presents both wind and rotor speed sensorless control for the direct-drive interior permanent magnet synchronous generator (IPMSG) with maximum power point tracking (MPPT) algorithm. The proposed method, without requiring the knowledge of wind speed, air density or turbine parameters, generates optimum speed command for speed control loop of vector controlled machine side converter. The MPPT algorithm based on perturbation and observation uses only estimated active power as its input to track peak output power points in accordance with wind speed change and incorporates proposed sensorless control to transfer maximum dc-link power from generator. In this work for the IPMSG, the rotor position and speed are estimated based on model reference adaptive system. Additionally, it incorporates flux weakening controller (FWC) for wide operating speed range at various wind speed and other disturbances. Matlab/Simulink based simulation model of the proposed sensorless MPPT control of IPMSG based WECS is built to verify the effectiveness of the system. The MPPT controller has been tested for variable wind speed conditions. The performance of the proposed WECS is also compared with the conventional control of WECS system. The proposed IPMSG based WECS incorporating the MPPT and sensorless algorithms is successfully implemented in real-time using the digital signal processor (DSP) board DS1104 for a laboratory 5 hp machine. A 5 hp DC motor is used as wind turbine to drive the IPMSG. The speed tracking performance and maximum power transfer capability of the proposed WECS are verified by both simulation and experimental results at different speed conditions