K.N. Ochije

Bio: K.N. Ochije is an academic researcher from University of Leicester. The author has contributed to research in topics: Ćuk converter & Flyback converter. The author has an hindex of 1, co-authored 1 publications receiving 8 citations.

A controlled PWM AC/DC converter for a high-speed brushless generator for minimum kVA rating

Abstract: This paper proposes a control technique for an ac/dc converter and high-speed single-phase brushless ac generator topology with a reactive armature winding. An ac-to-dc pulsewidth-modulation (PWM) converter is used with phase angle control to deliver a controlled power factor for a wide speed range while maintaining a low kVA rating of the converter and the generator. The generator is a flux-switching machine, derived from a combination of the inductor alternator and the switched reluctance machine. The electrical characteristics of the generator are determined from open-circuit, short-circuit, and load tests performed on an experimental generator. A Simulink model is developed for the ac-to-dc PWM converter and the simulated voltage and current waveforms show that the kVA rating of the converter and the generator can be minimized through control of the power factor of the generator. This novel generator is shown to be simple to control and can be used for micro turbine applications and efficient low-cost independent power generation. The converter also allows the machine to be used as an integrated starter alternator.

Alternate Poles Wound Flux-Switching Permanent-Magnet Brushless AC Machines

Abstract: Flux-switching permanent-magnet (FSPM) brushless machines have emerged as an attractive machine type by virtue of their high torque densities, simple and robust rotor structure, and the fact that permanent magnets and coils are both located on the stator. Both 2-D and 3-D finite element analyses are employed to compare the performance of a conventional all poles wound (double-layer winding) topology with that of three modular alternate poles wound (single-layer winding) topologies, in terms of output torque, flux-linkage, back EMF, and inductances. It is shown that the FSPM machine can be designed in this way without incurring a significant performance penalty, but that some degree of rotor skewing or a variation in stator and rotor pole combination may be required in order to maintain a sinusoidal back-EMF waveform and reduce the torque ripple. Experimental validation is reported for both conventional all poles wound and alternate poles wound FSPM machine topologies.

Fault-Tolerant Flux-Switching Permanent Magnet Brushless AC Machines

Abstract: Flux-switching permanent magnet (FSPM) brushless machines have emerged as an attractive machine type by virtue of their high torque densities, simple and robust rotor structure and the fact that permanent magnets and coils are both located on the stator. Both 2D and 3D finite element analyses (FEA) are employed to compare the performance of a standard topology with three modular, fault-tolerant designs in terms of output torque, flux-linkage, back-EMF and inductances. It is shown that the FSPM machine can be designed to be fault-tolerant without incurring a significant performance penalty, but that some degree of rotor skewing may be required in order to maintain a sinusoidal back-EMF waveform and reduce the torque ripple. Experimental validation is reported for both standard and fault-tolerant FSPM machine topologies.

Simulink model of controlled power factor flux switching generator system for embedded power generation

Abstract: This paper describes a Simulink model of a flux switching generator system FSG with controlled armature power factor, suitable for high speed applications. The generator is a flux-switching machine derived from an inductor alternator and the switched reluctance machine. Using an 8/4 configuration of this machine the electrical characteristics of this generator was determined using flux linkage and magneto motive force MMF data derived from finite element analysis FEA. The Simulink model was developed for the control and output power prediction for the flux switching generator system. Predictions using this model shows, agreement with the experimental results for controlled power factor operation. The complete system model developed using Matlab/Simulink and FEA can therefore be used in effective design and prototyping of the flux switching generator system.

A kind of switch current source with high order LC filter output

Abstract: a kind of switch current source with feedback loop compensation is presented in this paper to solve the problem that switching current source can not be applied in high-precision circuit. A good tradeoff has been made by this type of switch current source in improving the dynamic response and reducing low ripple. At the beginning of the paper, the model of BUCK-type circuit is built after analyzing the circuit. Next, the main factor which affects the stability of the system, the filter, is emphasized. The contradiction of high out band rejection and high stability which exists in LC filter is pointed out. To solve this problem, the program of feedback loop compensation is proposed; to verify this program the simulation result is presented. Finally, the implementation circuit of switch current source with high order LC filter output is presented.

Analysis and design of flux switching machine driver with APC control based on PIC18F2331

Abstract: Flux-switching motor (FSM) has the unique advantages of rugged structure, low cost, high power density, relative low level vibration and acoustic noise. In this paper, firstly, the power converter and control strategy of FSM was studied. Then the optical rotor position detecting appliance of FSM was designed and the controller for FSM based on PIC18F2331 was designed. The starting performance of FSM is studied and improved by changing the rotor shape. At last, the experiment of prototype machines was implemented to study the performance of the prototype machine with APC control.