Microturbine Power Converter System Utilizing a Six-Phase Permanent Magnet Synchronous Machine.

摘要

This thesis focuses on the research of the microturbine control system. A novel multi-functional six-phase back-to-back pulse width modulation (PWM) power converter system for microturbine generators is developed and researched. The system provides an interface between the variable-voltage variable-frequency six-phase super-high speed microturbine generator and the fixed-voltage fixed-frequency electric power grid.;The second part, which is based on the new model, utilizes a new circuit topology to simultaneously control PMSM operation at super-high speeds, achieve DC-link voltage control, and implement a parallel boost control strategy. A master and slave method is used to control the system AC-DC operation. A three-phase AC-DC active rectifier acts as the master rectifier. It controls the DC-link voltage and sends the current to the DC-link. The slave rectifier consists of a three-phase diode rectifier and a DC-DC boost chopper, which follows the DC-link voltage and sends the current to the DC-link.;The last part of the thesis develops three novel control methods for DC-AC conversion. These methods provide DC-link voltage protection, DC-link voltage sensorless operation, and a predictive PI controller. A new control method is introduced to provide DC-AC control. This method monitors the DC-link voltage and sends high-quality current into the grid at the same time so that control system reliability is increased. The proposed DC-link voltage-sensorless method is different from the traditional methods. In traditional methods, the differential technique is used to obtain the DC-link voltage. But in this new proposed method, the integral technique is utilized to estimate the DC-link voltage. The new PI controller with predictive function is proposed, which simultaneously provides the advantages of the predictive control and PI control. The inverter output attains very high quality under stable conditions and follows the reference without any delay.;The thesis is composed of three parts. The first part develops a model of the six-phase permanent magnet synchronous machine (PMSM) to analyse its characteristics and to simulate the control process with Matlab/Simulink. This new model includes the advantages of the two existing models. Through this new model, the relationship between the two existing models is built.