Yusuf Yasa

Investigating Operating Modes and Converter Options of Dual Winding Permanent Magnet Synchronous Machines for Hybrid Electric Vehicles

Summary form only given. This paper investigates the operating modes and converter options of dual winding permanent magnet synchronous machines (DWPMSMs) that are used to drive accessories in hybrid electric vehicles. In this application, DWPMSM operate in three different modes: 1) motor-only; 2) generator-only; and 3) simultaneous motor-generator modes. Motor-only and generator-only operations can be treated independently as long as two winding sets are magnetically decoupled. Simultaneous motor-generator mode links two winding sets through a mechanical shaft. As part of this study, the impact of dual winding set usage on the machines output and performance is also investigated. Experimental results are given for each mode. The converter options of generator winding were investigated as well. These options include uncontrolled rectifier with dc-dc converter and controlled rectifier. Two converters are compared for their impacts on efficiency and generator current harmonics. The relationship between speed and converter control variable is given for various back electromotive force constant values of the DWPMSM.

Unbalanced fault analysis of doubly fed induction generator drive system for wind turbine applications

This paper presents detailed analysis of the doubly fed induction generator (DFIG), converters and step-up transformer under normal and fault conditions for wind turbine applications. 2.5 MW DFIG is modeled through finite element analysis in Ansoft-Maxwell, and the simulation is coupled to Ansoft-Simplorer and Matlab-Simulink for the drive circuit and controller implementation. Single phase to ground short circuit which has the highest probability to occur in the grid is tested through coupled simulators. The effect of short circuit stator current on the rotor currents are analyzed for rotor side converter protection. The FFT analysis of the stator and rotor fluxes in simulation during fault conditions are carried to be able to develop advanced control techniques in eliminating the harmonics and protecting the overall drive system. Experimental 7.5 HP DFIG test system has been developed to verify the simulation results. The FFT analysis of stator fluxes under fault condition from experimental results agrees well with the simulation results.

Analysis of doubly fed induction generator wind turbine system during one phase-to-ground fault

This paper presents detailed analysis of doubly fed induction generator (DFIG) wind turbine electrical components during normal and unbalanced fault condition. Wind turbine components are individually modeled and then combined in a simulation process which is called coupled simulation. The coupled simulation results show that grid frequency oscillation occurs on q and d axis currents under one phase-ground fault condition. Experimental study has been done to show the effects of fault on rotor currents. Same behavior is also found in experimental rotor currents. Additionally experimental study shows that rotor currents are very sensitive to the grid fault voltage level.

A new electric accessory drive system for hybrid electric vehicles

This paper presents a new electric accessory drive system for hybrid electric vehicles. The system offers cost and space advantages. In this concept, dual winding electric machine with simultaneous motor and generator functions is used. The electric machine provides power for all accessory loads such as steering pump, compressors, and 12V loads. If the engine is on, accessory loads are driven by engine through a belt like conventional vehicle. If the engine is off, electric machines motoring action starts and provides mechanical power to accessory loads. Simultaneously, the generator windings provide power for 12 V loads. Converter options for generator were also investigated and preliminary experimental results were presented.

Comparative design of direct drive PM synchronous motors in gearless elevator systems

In todays world electrical machines become irreplaceable for human beings to continue daily routines. Due to the features such as high efficiency, high starting torque, and silent working, permanent magnet synchronous motors (PMSM) are becoming more common in many applications. One of these applications is gearless elevator system where PMSM seems to be the best candidate so far. In this paper, comparative design of PMSM for gearless elevator has been investigated. Maxwell 2D Finite element analysis software has been used in this study. With comparative design, the influence of pole count on the machine performance is studied. Also, material consumption, weight and costs of two machines have been compared.

Design considerations for dual winding permanent magnet synchronous machines

This paper presents design and analysis performed for a dual winding electric machine. Windings of the machine are concentrated type so that electrical and magnetic isolation is maintained. For this reason, the proposed structure could be a reasonable candidate for fault tolerant applications. As required by some applications (electric accessory drive system (EADS) for hybrid electric vehicles), simultaneous motoring and generating operations can be implemented in a single housing of electric machine. Design considerations of the proposed electric machine are outlined in the paper. Also a comparison between distributed winding topology and concentrated winding topologies is performed. Finally experimental results discussed.

Design Considerations of Electromagnetic Brakes for Servo Applications

Servo motors have increased popularity in industrial and robotics applications. Also, servo motors employ electromagnetic brakes for holding and emergency braking. So, electromechanical brakes found numerous fields due to operation and emergency requirements. The design procedure of an electromagnetic brake requires multidisciplinary approach in terms of mechanical, electrical and thermal aspects. This paper focuses on design, development and experimental verification of an electromagnetic brake. The electromagnetic and thermal design is handled in both FEA and analytical models. Electromagnetic brake prototype is produced and design aspects are experimentally verified. Good agreement between the test results and the prototype is achieved.

Effect of distributed airgap in the stator for acoustic noise reduction in switched reluctance motors

This paper presents a distributed airgap in the stator of switched reluctance machines (SRMs) to reduce the vibration and the acoustic noise levels. Distributed airgap is placed in stator tooth or yoke to analyze its effectiveness on the electromagnetic and mechanical performances. According to the observations, it has been found that when the distributed airgap is placed in the stator teeth, the generated radial force is significantly reduced. In addition, the technique reduces the stator surface deformation considerably by playing a role of spring. When the distributed airgap is placed in the stator yoke, radial force does not change significantly however it reduces the stator yoke deformation by behaving as a spring. The detailed comparison of two proposed methods is performed by electromagnetic and mechanical/acoustical finite element tools.

Comparison of SVPWM, SPWM and HCC control techniques in power control of PMSG used in wind turbine systems

In this paper, the performance of space vector pulse width modulation (SVPWM), sinusoidal pulse width modulation (SPWM) and hysteresis current control (HCC) control techniques used in power control with back to back converter of permanent magnet synchronous generator used in wind turbines are comparatively analyzed in terms of dynamic response, total harmonic distortion (THD), torque ripple and current ripple. Furthermore, SVPWM and SPWM are compared in terms of the using DC link voltage. Analysis of system is realized with MATLAB/Simulink program. There is not paper that together of these three control techniques are compared in terms of common results or values in literature. Permanent magnet synchronous generator (PMSG) is used in simulations is surface mounted, bipolar and its power is 1.8 kW. However, PMSMs energy transmission to grid is made with Field Oriented Control (FOC). According to analysis results, it has been observed that SVPWM generally has more efficient results than both HCC and SPWM control technique. Also, it is observed that SVPWM can produce about 15 percent higher than SPWM in output voltage.

Design and analysis of generator and converters for outer rotor direct drive gearless small-scale wind turbines

This paper focuses on design and analysis issues of direct drive gearless generator which are widely used in small-scale wind turbines. Permanent magnet synchronous generator (PMSG) is designed that is considered for 2.5 kW continuous and 6 kW peak power. Then power converter topologies are briefly discussed then one of them is selected to develop. The finite element model of PMSG is integrated with power converters and simulated which is named coupled simulation provides more realistic results. The results are thought to be guidance for wind turbine developers and manufacturers.