Prediction of rotor position in switched reluctance motor drives at standstill and unexcited rotating shaft conditions

Over the years, Switched Reluctance Machine (SRM) drives have proven themselves to be a solution for extreme working environments. These include applications in the automotive, military, aerospace and domestic sector. The robustness of this machine can be attributed to its simple geometry and absence of any magnetic source on the rotor. For the proper start-up and precise control of the SRM drive, an accurate detection of rotor position is necessary. Conventional approach using an external position sensor mounted on the shaft has numerous drawbacks. This provides the necessary incentive to develop a sensorless technique that is accurate, cost-effective, reliable, and does not unnecessarily increase the size to the existing system. The SRM has an inductance profile symmetric about each phase which is a function of position and current. This profile can be divided into regions having a unique order such that one of the phases in each region varies linearly as the position for a fixed value of current. An accurate knowledge of the value of inductance for this phase would allow us to precisely calculate the rotor position. Based on this fact, a method has been presented which conforms to all requirements and is effective at standstill as well as flying shaft conditions --Abstract, page iii