| Switched Reluctance Motor (SRM) drive is considered as a possible alternative to other conventional variable speed drives because of several advantages. However, necessity of external position sensor and high level of acoustic noise are some of the drawbacks.; Switched Reluctance Motor works on the principle of reluctance torque production, and rotor position feedback is required for its basic operation. External position sensors such as resolvers or optical encoders are usually used. These add to the system cost and drive dimensions and also cause reliability concerns, and hence it is preferable to use sensorless control.; Several research papers have been published in literature that deal with position sensorless control of SRMs. The phase inductances in an SRM are periodic functions of the rotor position, and this attribute is exploited for achieving sensorless control.; In this dissertation, a sensorless control method for SRM drives based on the inductance model of the motor is developed. The voltage equation representing the active phase has inductance term in it, which is a function of rotor position and the phase current. If the phase inductance can be expressed analytically, then the voltage equation can be solved to get the rotor position, since the other quantities in the equation are either measurables or fixed parameters.; In this research, first, an analytical model for the phase inductance that considers its position and current dependency is developed. From the inductance model and the voltage equations of the active phase, the sensorless control algorithm is formulated.; A detailed computer model of the drive is developed in which the theory of the proposed sensorless scheme is verified. As a next major step, a prototype is designed and developed and the performance of the sensorless control algorithm over a wide range of speed and load is tested. As a final step, the characteristics of the sensorless, scheme such as resolution, accuracy, effect of measurement noise and dynamic speed range are studied in detail, which is required in order to use it in high performance applications. |
